WorldWideScience

Sample records for steels simulations des

  1. STEFINS: a steel freezing integral simulation program

    International Nuclear Information System (INIS)

    Frank, M.V.

    1980-09-01

    STEFINS (STEel Freezing INtegral Simulation) is a computer program for the calculation of the rate of solidification of molten steel on solid steel. Such computations arize when investigating core melt accidents in fast reactors. In principle this problem involves a coupled two-dimensional thermal and hydraulic approach. However, by physically reasonable assumptions a decoupled approach has been developed. The transient solidification of molten steel on a cold wall is solved in the direction normal to the molten steel flow and independent from the solution for the molten steel temperature and Nusselt number along the direction of flow. The solutions to the applicable energy equations have been programmed in cylindrical and slab geometries. Internal gamma heating of steel is included

  2. Plan Validation Using DES and Agent-based Simulation

    National Research Council Canada - National Science Library

    Wong, Teck H; Ong, Kim S

    2008-01-01

    .... This thesis explores the possibility of using a multi-agent system (MAS) to generate the aggressor's air strike plans, which could be coupled with a low resolution Discrete Event Simulation (DES...

  3. Experimental and numerical simulation of carbon manganese steel ...

    African Journals Online (AJOL)

    Experimental and numerical simulation of carbon manganese steel for cyclic plastic behaviour. J Shit, S Dhar, S Acharyya. Abstract. The paper deals with finite element modeling of saturated low cycle fatigue and the cyclic hardening phenomena of the materials Sa333 grade 6 carbon steel and SS316 stainless steel.

  4. Numerical Simulation of Duplex Steel Multipass Welding

    Directory of Open Access Journals (Sweden)

    Giętka T.

    2016-12-01

    Full Text Available Analyses based on FEM calculations have significantly changed the possibilities of determining welding strains and stresses at early stages of product design and welding technology development. Such an approach to design enables obtaining significant savings in production preparation and post-weld deformation corrections and is also important for utility properties of welded joints obtained. As a result, it is possible to make changes to a simulated process before introducing them into real production as well as to test various variants of a given solution. Numerical simulations require the combination of problems of thermal, mechanical and metallurgical analysis. The study presented involved the SYSWELD software-based analysis of GMA welded multipass butt joints made of duplex steel sheets. The analysis of the distribution of stresses and displacements were carried out for typical welding procedure as during real welding tests.

  5. Simulation of a stainless steel multipass weldment

    Energy Technology Data Exchange (ETDEWEB)

    Lejeail, Y.; Cabrillat, M.T. [CEA Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France)

    1995-12-31

    Several problems in nuclear power plants are due to shrinkage and distortion of welded structures and the associated residual stresses. In this context, a stainless steel multipass weldment realized in a H type constrained specimen has been calculated by means of finite element method. The temperatures obtained from a 3 D modified Rosenthal equation are compared with the experimental ones, and are then used for the 2 D simulation in which a linear Kinematic hardening is assumed in relation to a Von Mises plasticity criteria. Materials data are well known up to very high temperatures (1200{sup 0} C) and are introduced in the model. Experimental and calculated displacements after the first pass are compared and a discussion points out what improvements should be made for a better agreement. (author). 3 refs., 8 figs, 1 tab.

  6. Simulation of continuous cast steel product solidification

    Directory of Open Access Journals (Sweden)

    Ardelean, E.

    2007-06-01

    Full Text Available Primary cooling – inside the tundish – has a great impact over the thickness of the solidified steel crust. If on exiting the tundish the crust is too thin, it can punch and break, as a result of the ferrostatic pressure exerted from the inside by the liquid steel as well as because of the weight of the molten steel. The parameters that influence the amount of dissipated heat depend on the cooling water flow of the tundish, on the pressure and temperature of the cooling water but also on the overheating of the continuously cast steel. The secondary cooling takes place at the exit of the semi-finished product from the tundish, when the solidification is supposed to take place all along the cross section of the strand. In order to achieve it, in addition to a correctly managed primary cooling, it is necessary to obtain the proper correlation of the factors that influence the secondary cooling as well: the water flow rate long the three zones of the installation and its pressure in the secondary circuit. All these have in view a proper solidification length; an intense cooling can generate cracks due to the thermal stress, while a too slow cooling can generate a partial solidification of the strand up to the cropping machine area. The paper presents a mathematical simulation of the continuously cast steel solidification.

    El enfriamiento primario del cristalizador tiene una gran importancia sobre el espesor de la costra de acero solidificado. Si al salir del cristalizador, esta costra es demasiado sutil, bajo la acción de la presión ferro estática ejercitada por el acero líquido del interior y gracias el peso propio del hilo, ésta, puede perforar resultando su rompimiento. Los parámetros que influenyen sobre la cantidad de calor cedida dependen del agua de enfriamiento del catalizador, de la presión y de la temperatura de agua de enfriamiento, pero también del sobrecalentamiento del acero fundido continuamente. A la salida del

  7. Simulation modeling for quality and productivity in steel cord manufacturing

    OpenAIRE

    Türkseven, Can Hulusi; Turkseven, Can Hulusi; Ertek, Gürdal; Ertek, Gurdal

    2003-01-01

    We describe the application of simulation modeling to estimate and improve quality and productivity performance of a steel cord manufacturing system. We describe the typical steel cord manufacturing plant, emphasize its distinguishing characteristics, identify various production settings and discuss applicability of simulation as a management decision support tool. Besides presenting the general structure of the developed simulation model, we focus on wire fractures, which can be an important...

  8. Laser cutting of thick steel plates and simulated steel components using a 30 kW fiber laser

    International Nuclear Information System (INIS)

    Tamura, Koji; Ishigami, Ryoya; Yamagishi, Ryuichiro

    2016-01-01

    Laser cutting of thick steel plates and simulated steel components using a 30 kW fiber laser was studied for application to nuclear decommissioning. Successful cutting of carbon steel and stainless steel plates up to 300 mm in thickness was demonstrated, as was that of thick steel components such as simulated reactor vessel walls, a large pipe, and a gate valve. The results indicate that laser cutting applied to nuclear decommissioning is a promising technology. (author)

  9. Simulation of Structural Transformations in Heating of Alloy Steel

    Science.gov (United States)

    Kurkin, A. S.; Makarov, E. L.; Kurkin, A. B.; Rubtsov, D. E.; Rubtsov, M. E.

    2017-07-01

    Amathematical model for computer simulation of structural transformations in an alloy steel under the conditions of the thermal cycle of multipass welding is presented. The austenitic transformation under the heating and the processes of decomposition of bainite and martensite under repeated heating are considered. Amethod for determining the necessary temperature-time parameters of the model from the chemical composition of the steel is described. Published data are processed and the results used to derive regression models of the temperature ranges and parameters of transformation kinetics of alloy steels. The method developed is used in computer simulation of the process of multipass welding of pipes by the finite-element method.

  10. Quenching simulation of steel grinding balls

    Energy Technology Data Exchange (ETDEWEB)

    Zapata-Hernandez, O.; Reyes, L. A.; Camurri, C.; Carrasco, C.; Garza-Monte-de-Oca, F.; Colas, R.

    2015-07-01

    The phase transformations of high carbon steel during quenching and equalizing were modelled using commercial computer packages based on the finite element method and the kinetic transformation of steel. The model was used to predict the temperature and microstructural changes taking place within balls of two different sizes that are used for grinding mineral ores. A good correlation between the temperatures measured by inserted thermocouples and those predicted by the model was obtained after modifying the thermal conductivity of the steel within the temperature domain at which mixed phases are present. The phase transformations predicted were confirmed by metallographic analyses. (Author)

  11. Studies on defect evolution in steels: experiments and computer simulations

    International Nuclear Information System (INIS)

    Sundar, C.S.

    2011-01-01

    In this paper, we present the results of our on-going studies on steels that are being carried out with a view to develop radiation resistant steels. The focus is on the use of nano-dispersoids in alloys towards the suppression of void formation and eventual swelling under irradiation. Results on the nucleation and growth of TiC precipitates in Ti modified austenitic steels and investigations on nano Yttria particles in Fe - a model oxide dispersion ferritic steel will be presented. The experimental methods of ion beam irradiation and positron annihilation spectroscopy have been used to elucidate the role of minor alloying elements on swelling behaviour. Computer simulation of defect processes have been carried out using ab-initio methods, molecular dynamics and Monte Carlo simulations. Our perspectives on addressing the multi-scale phenomena of defect processes leading to radiation damage, through a judicious combination of experiments and simulations, would be presented. (author)

  12. RPV-1: a first virtual reactor to simulate irradiation effects in light water reactor pressure vessel steels; RPV-1: un premier reacteur virtuel pour simuler les effets d'irradiation dans les aciers de cuve des reacteurs a eau legere

    Energy Technology Data Exchange (ETDEWEB)

    Jumel, St

    2005-01-15

    The presented work was aimed at building a first VTR (virtual test reactor) to simulate irradiation effects in pressure vessel steels of nuclear reactor. It mainly consisted in: - modeling the formation of the irradiation induced damage in such steels, as well as their plasticity behavior - selecting codes and models to carry out the simulations of the involved mechanisms. Since the main focus was to build a first tool (rather than a perfect tool), it was decided to use, as much as possible, existing codes and models in spite of their imperfections. - developing and parameterizing two missing codes: INCAS and DUPAIR. - proposing an architecture to link the selected codes and models. - constructing and validating the tool. RPV-1 is made of five codes and two databases which are linked up so as to receive, treat and/or transmit data. A user friendly Python interface facilitates the running of the simulations and the visualization of the results. RPV-1 relies on many simplifications and approximations and has to be considered as a prototype aimed at clearing the way. According to the functionalities targeted for RPV-1, the main weakness is a bad Ni and Mn sensitivity. However, the tool can already be used for many applications (understanding of experimental results, assessment of effects of material and irradiation conditions,....). (O.M.)

  13. Reaction of uranium and plutonium carbides with austenitic steels; Reaction des carbures d'uranium et de plutonium avec des aciers austenitiques

    Energy Technology Data Exchange (ETDEWEB)

    Mouchnino, M [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-07-01

    The reaction of uranium and plutonium carbides with austenitic steels has been studied between 650 and 1050 deg. C using UC, steel and (UPu)C, steel diffusion couples. The steels are of the type CN 18.10 with or without addition of molybdenum. The carbides used are hyper-stoichiometric. Tests were also carried out with UCTi, UCMo, UPuCTi and UPuCMo. Up to 800 deg. C no marked diffusion of carbon into stainless steel is observed. Between 800 and 900 deg. C the carbon produced by the decomposition of the higher carbides diffuses into the steel. Above 900 deg. C, decomposition of the monocarbide occurs according to a reaction which can be written schematically as: (U,PuC) + (Fe,Ni,Cr) {yields} (U,Pu) Fe{sub 2} + Cr{sub 23}C{sub 6}. Above 950 deg. C the behaviour of UPuCMo and that of the titanium (CN 18.12) and nickel (NC 38. 18) steels is observed to be very satisfactory. (author) [French] La reaction des carbures d'uranium et de plutonium avec des aciers austenitiques a ete etudiee entre 650 deg. C et 1050 deg. C a partir de couples de diffusion UC, acier et (UPu)C, acier. Les aciers sont du type CN 18.10 avec ou sans addition de molybdene. Les carbures utilises sont hyper-stoechiometriques. En outre on a fait des essais avec UCTi, UCMo, UPuCTi, UPuCMo. Jusqu'a 800 deg. C on ne detecte pas de diffusion sensible du carbone dans l'acier inoxydable. Entre 800 et 900 deg. C il y a diffusion dans l'acier du carbone provenant de la decomposition des carbures superieurs. A partir de 900 deg. C il y a decomposition du monocarbure selon une reaction que l'on ecrit schematiquement: (U,PuC) + (Fe, Ni, Cr) {yields} (U,Pu)Fe{sub 2} + Cr{sub 23}C{sub 6}. Nous notons a 950 deg. C le bon comportement de UPuCMo ainsi que celui des aciers au titane (CN 18. 12) et au nickel (NC 38.18). (auteur)

  14. Computer simulation of sensitization in stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Logan, R W

    1983-12-20

    Stainless steel containers are prime candidates for the containment of nuclear waste in tuff rock. The thermal history of a container involves exposure to temperatures of 500 to 600/sup 0/C when it is welded and possibly filled with molten waste glass, followed by hundreds of years exposure in the 100 to 300/sup 0/C range. The problems of short- and long-term sensitization in stainless steels have been addressed by two computer programs. The TTS program uses classical nucleation and growth theory plus experimental input to predict the onset of precipitation or sensitization under complex thermal histories. The FEMGB program uses quadratic finite-element methods to analyze diffusion processes and chromium depletion during precipitate growth. The results of studies using both programs indicate that sensitization should not be a problem in any of the austenitic stainless steels considered. However, more precise information on the process thermal cycles, especially during welding of the container, is needed. Contributions from dislocation pipe diffusion could promote long-term low-temperature sensitization.

  15. Quenching simulation of steel grinding balls

    Directory of Open Access Journals (Sweden)

    Zapata-Hernández, Oscar

    2015-09-01

    Full Text Available The phase transformations of high carbon steel during quenching and equalizing were modelled using commercial computer packages based on the finite element method and the kinetic transformation of steel. The model was used to predict the temperature and microstructural changes taking place within balls of two different sizes that are used for grinding mineral ores. A good correlation between the temperatures measured by inserted thermocouples and those predicted by the model was obtained after modifying the thermal conductivity of the steel within the temperature domain at which mixed phases are present. The phase transformations predicted were confirmed by metallographic analyses.Las transformaciones de fase en aceros de alto carbono durante su temple y un posterior periodo de estabilización fueron modelizadas por medio del uso de paquetes computacionales basados en el método del elemento finito y de la transformación cinética de los aceros. El modelo se usó para predecir los cambios de temperatura y microestructura que se presentan en bolas de dos diferentes tamaños empleadas en estaciones de molienda de minerales. Se encontró una buena correlación entre las temperaturas medidas mediante la inserción de termopares y aquellas predichas por el modelo una vez que se modificó la conductividad térmica del acero en el intervalo mixto de fases. La predicción de las transformaciones de fase se confirmó a través del análisis metalográfico.

  16. Weldability investigation steel P 91 by weld thermal cycle simulation

    Directory of Open Access Journals (Sweden)

    M. Dunđer

    2015-07-01

    Full Text Available This paper elaborates results of hardness and impact energy of thermal cycle simulated specimens of high-alloy steel P 91 and their dependence on cooling time from 800 to 500 °C. Results were obtained by measuring hardness HV 1 and by experimental testing of Charpy notched specimens. Metallographic analysis of samples was performed on scanning electronic microscope.

  17. Mechanism and simulation of droplet coalescence in molten steel

    Science.gov (United States)

    Ni, Bing; Zhang, Tao; Ni, Hai-qi; Luo, Zhi-guo

    2017-11-01

    Droplet coalescence in liquid steel was carefully investigated through observations of the distribution pattern of inclusions in solidified steel samples. The process of droplet coalescence was slow, and the critical Weber number ( We) was used to evaluate the coalescence or separation of droplets. The relationship between the collision parameter and the critical We indicated whether slow coalescence or bouncing of droplets occurred. The critical We was 5.5, which means that the droplets gradually coalesce when We ≤ 5.5, whereas they bounce when We > 5.5. For the carbonate wire feeding into liquid steel, a mathematical model implementing a combined computational fluid dynamics (CFD)-discrete element method (DEM) approach was developed to simulate the movement and coalescence of variably sized droplets in a bottom-argon-blowing ladle. In the CFD model, the flow field was solved on the premise that the fluid was a continuous medium. Meanwhile, the droplets were dispersed in the DEM model, and the coalescence criterion of the particles was added to simulate the collision- coalescence process of the particles. The numerical simulation results and observations of inclusion coalescence in steel samples are consistent.

  18. Measurement and simulation of deformation and stresses in steel casting

    Science.gov (United States)

    Galles, D.; Monroe, C. A.; Beckermann, C.

    2012-07-01

    Experiments are conducted to measure displacements and forces during casting of a steel bar in a sand mold. In some experiments the bar is allowed to contract freely, while in others the bar is manually strained using embedded rods connected to a frame. Solidification and cooling of the experimental castings are simulated using a commercial code, and good agreement between measured and predicted temperatures is obtained. The deformations and stresses in the experiments are simulated using an elasto-viscoplastic finite-element model. The high temperature mechanical properties are estimated from data available in the literature. The mush is modeled using porous metal plasticity theory, where the coherency and coalescence solid fraction are taken into account. Good agreement is obtained between measured and predicted displacements and forces. The results shed considerable light on the modeling of stresses in steel casting and help in developing more accurate models for predicting hot tears and casting distortions.

  19. Measurement and simulation of deformation and stresses in steel casting

    International Nuclear Information System (INIS)

    Galles, D; Beckermann, C; Monroe, C A

    2012-01-01

    Experiments are conducted to measure displacements and forces during casting of a steel bar in a sand mold. In some experiments the bar is allowed to contract freely, while in others the bar is manually strained using embedded rods connected to a frame. Solidification and cooling of the experimental castings are simulated using a commercial code, and good agreement between measured and predicted temperatures is obtained. The deformations and stresses in the experiments are simulated using an elasto-viscoplastic finite-element model. The high temperature mechanical properties are estimated from data available in the literature. The mush is modeled using porous metal plasticity theory, where the coherency and coalescence solid fraction are taken into account. Good agreement is obtained between measured and predicted displacements and forces. The results shed considerable light on the modeling of stresses in steel casting and help in developing more accurate models for predicting hot tears and casting distortions.

  20. Precipitation response of austenitic stainless steel to simulated fusion irradiation

    International Nuclear Information System (INIS)

    Maziasz, P.J.

    1978-01-01

    The precipitation response of annealed type 316 stainless steel irradiated in HFIR is studied and compared to previously observed thermal aging and fast reactor irradiation responses. Irradiation in HFIR simultaneously produces high levels of helium and displacement damage and partially simulates a fusion environment. Samples have been irradiated at temperatures from 550 to 680 0 C to fluences producing up to 3300 appm He and 47 dpa

  1. High temperature cracking of steels: effect of geometry on creep crack growth laws; Fissuration des aciers a haute temperature: effet de la geometrie sur la transferabilite des lois de propagation

    Energy Technology Data Exchange (ETDEWEB)

    Kabiri, M.R

    2003-12-01

    This study was performed at Centre des Materiaux de l'Ecole des Mines de Paris. It deals with identification and transferability of high temperature creep cracking laws of steels. A global approach, based on C{sup *} and J non-linear fracture mechanics parameters has been used to characterize creep crack initiation and propagation. The studied materials are: the ferritic steels 1Cr-1Mo-1/4V (hot and cold parts working at 540 and 250 C) used in the thermal power stations and the austenitic stainless steel 316 L(N) used in the nuclear power stations. During this thesis a data base was setting up, it regroups several tests of fatigue, creep, creep-fatigue, and relaxation. Its particularity is to contain several creep tests (27 tests), achieved at various temperatures (550 to 650 C) and using three different geometries. The relevance of the C{sup *} parameter to describe the creep crack propagation was analysed by a means of systematic study of elasto-viscoplastic stress singularities under several conditions (different stress triaxiality). It has been shown that, besides the C{sup *} parameter, a second non singular term, denoted here as Q{sup *}, is necessary to describe the local variables in the vicinity of the crack tip. Values of this constraint parameter are always negative. Consequently, application of typical creep crack growth laws linking the creep crack growth rate to the C{sup *} parameter (da/dt - C{sup *}), will be conservative for industrial applications. Furthermore, we showed that for ferritic steels, crack incubation period is important, therefore a correlation of Ti - C{sup *} type has been kept to predict crack initiation time Ti. For the austenitic stainless steel, the relevant stage is the one of the crack propagation, so that a master curve (da/dt - C{sup *}), using a new data analysis method, was established. Finally, the propagation of cracks has been simulated numerically using the node release technique, allowing to validate analytical

  2. simulation du climat futur et des rendements agricoles en region

    African Journals Online (AJOL)

    ACSS

    REGION SOUDANO-SAHELIENNE EN REPUBLIQUE DU BENIN. S. KATE, O. TEKA1, ... La présente étude a été initiée pour déterminer les caractéristiques des rendements des principales ..... Climate change in cities due to global warming ...

  3. Steel Fibers Reinforced Concrete Pipes - Experimental Tests and Numerical Simulation

    Science.gov (United States)

    Doru, Zdrenghea

    2017-10-01

    The paper presents in the first part a state of the art review of reinforced concrete pipes used in micro tunnelling realised through pipes jacking method and design methods for steel fibres reinforced concrete. In part two experimental tests are presented on inner pipes with diameters of 1410mm and 2200mm, and specimens (100x100x500mm) of reinforced concrete with metal fibres (35 kg / m3). In part two experimental tests are presented on pipes with inner diameters of 1410mm and 2200mm, and specimens (100x100x500mm) of reinforced concrete with steel fibres (35 kg / m3). The results obtained are analysed and are calculated residual flexural tensile strengths which characterise the post-cracking behaviour of steel fibres reinforced concrete. In the third part are presented numerical simulations of the tests of pipes and specimens. The model adopted for the pipes test was a three-dimensional model and loads considered were those obtained in experimental tests at reaching breaking forces. Tensile stresses determined were compared with mean flexural tensile strength. To validate tensile parameters of steel fibres reinforced concrete, experimental tests of the specimens were modelled with MIDAS program to reproduce the flexural breaking behaviour. To simulate post - cracking behaviour was used the method σ — ε based on the relationship stress - strain, according to RILEM TC 162-TDF. For the specimens tested were plotted F — δ diagrams, which have been superimposed for comparison with the similar diagrams of experimental tests. The comparison of experimental results with those obtained from numerical simulation leads to the following conclusions: - the maximum forces obtained by numerical calculation have higher values than the experimental values for the same tensile stresses; - forces corresponding of residual strengths have very similar values between the experimental and numerical calculations; - generally the numerical model estimates a breaking force greater

  4. Corrosion of a carbon steel in simulated liquid nuclear wastes

    International Nuclear Information System (INIS)

    Saenz Gonzalez, Eduardo

    2005-01-01

    This work is part of a collaboration agreement between CNEA (National Atomic Energy Commission of Argentina) and USDOE (Department of Energy of the United States of America), entitled 'Tank Corrosion Chemistry Cooperation', to study the corrosion behavior of carbon steel A537 class 1 in different simulated non-radioactive wastes in order to establish the safety concentration limits of the tank waste chemistry at Hanford site (Richland-US). Liquid high level nuclear wastes are stored in tanks made of carbon steel A537 (ASTM nomenclature) that were designed for a service life of 20 to 50 years. A thickness reduction of some tank walls, due to corrosion processes, was detected at Hanford site, beyond the existing predicted values. Two year long-term immersion tests were started using non radioactive simulated liquid nuclear waste solutions at 40 C degrees. This work extends throughout the first year of immersion. The simulated solutions consist basically in combinations of the 10 most corrosion significant chemical components: 5 main components (NaNO 3 , NaCl, NaF, NaNO 2 and NaOH) at three concentration levels and 5 secondary components at two concentration levels. Measurements of the general corrosion rate with time were performed for carbon steel coupons, both immersed in the solutions and in the vapor phases, using weight loss and electrochemistry impedance spectroscopy techniques. Optic and scanning electron microscopy examination, analysis of U-bend samples and corrosion potential measurements, were also done. Localized corrosion susceptibility (pitting and crevice corrosion) was assessed in isolated short-term tests by means of cyclic potentiodynamic polarization curves. The effect of the simulated waste composition on the corrosion behavior of A537 steel was studied based on statistical analyses. The Surface Response Model could be successfully applied to the statistical analysis of the A537 steel corrosion in the studied solutions. General corrosion was not

  5. Simulation of Friction Stir Processing in 304L Stainless Steel

    Directory of Open Access Journals (Sweden)

    Miles M.P.

    2016-01-01

    Full Text Available A major dilemma facing the nuclear industry is repair or replacement of stainless steel reactor components that have been exposed to neutron irradiation. When conventional fusion welding is used for weld repair, the high temperatures and thermal stresses inherent in the process enhance the growth of helium bubbles, causing intergranular cracking in the heat-affected zone (HAZ. Friction stir processing (FSP has potential as a weld repair technique for irradiated stainless steel, because it operates at much lower temperatures than fusion welding, and is therefore less likely to cause cracking in the HAZ. Numerical simulation of the FSP process in 304L stainless steel was performed using an Eulerian finite element approach. Model input required flow stresses for the large range of strain rates and temperatures inherent in the FSP process. Temperature predictions in three locations adjacent to the stir zone were accurate to within 4% of experimentally measure values. Prediction of recrystallized grain size at a location about 6mm behind the tool center was less accurate, because the empirical model employed for the prediction did not account for grain growth that occurred after deformation in the experiment was halted.

  6. Micromechanics based simulation of ductile fracture in structural steels

    Science.gov (United States)

    Yellavajjala, Ravi Kiran

    The broader aim of this research is to develop fundamental understanding of ductile fracture process in structural steels, propose robust computational models to quantify the associated damage, and provide numerical tools to simplify the implementation of these computational models into general finite element framework. Mechanical testing on different geometries of test specimens made of ASTM A992 steels is conducted to experimentally characterize the ductile fracture at different stress states under monotonic and ultra-low cycle fatigue (ULCF) loading. Scanning electron microscopy studies of the fractured surfaces is conducted to decipher the underlying microscopic damage mechanisms that cause fracture in ASTM A992 steels. Detailed micromechanical analyses for monotonic and cyclic loading are conducted to understand the influence of stress triaxiality and Lode parameter on the void growth phase of ductile fracture. Based on monotonic analyses, an uncoupled micromechanical void growth model is proposed to predict ductile fracture. This model is then incorporated in to finite element program as a weakly coupled model to simulate the loss of load carrying capacity in the post microvoid coalescence regime for high triaxialities. Based on the cyclic analyses, an uncoupled micromechanics based cyclic void growth model is developed to predict the ULCF life of ASTM A992 steels subjected to high stress triaxialities. Furthermore, a computational fracture locus for ASTM A992 steels is developed and incorporated in to finite element program as an uncoupled ductile fracture model. This model can be used to predict the ductile fracture initiation under monotonic loading in a wide range of triaxiality and Lode parameters. Finally, a coupled microvoid elongation and dilation based continuum damage model is proposed, implemented, calibrated and validated. This model is capable of simulating the local softening caused by the various phases of ductile fracture process under

  7. CFD simulations in the nuclear containment using the DES turbulence models

    International Nuclear Information System (INIS)

    Ding, Peng; Chen, Meilan; Li, Wanai; Liu, Yulan; Wang, Biao

    2015-01-01

    Highlights: • The k-ε based DES model is used in the nuclear containment simulation. • The comparison of results between different turbulent models is obtained. • The superiority of DES models is analyzed. • The computational efficiency with the DES turbulence models is explained. - Abstract: Different species of gases would be released into the containment and cause unpredicted disasters during the nuclear severe accidents. It is important to accurately predict the transportation and stratification phenomena of these gas mixtures. CFD simulations of these thermal hydraulic issues in nuclear containment are investigated in this paper. The main work is to study the influence of turbulence model on the calculation of gas transportation and heat transfer. The k-ε based DES and other frequently used turbulence models are used in the steam and helium release simulation in THAI series experiment. This paper will show the superiority of the DES turbulence model in terms of computational efficiency and accuracy with the experimental results, and analyze the necessities of DES model to simulate the large-scale containment flows with both laminar and turbulence regions

  8. CFD simulations in the nuclear containment using the DES turbulence models

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Peng [School of Engineering, Sun Yat-Sen University, Guangzhou (China); Chen, Meilan [China Nuclear Power Technology Research Institute, Shenzhen (China); Li, Wanai, E-mail: liwai@mail.sysu.edu.cn [Sino-French Institute of Nuclear Engineering & Technology, Sun Yat-Sen University, Guangzhou (China); Liu, Yulan [School of Engineering, Sun Yat-Sen University, Guangzhou (China); Wang, Biao [Sino-French Institute of Nuclear Engineering & Technology, Sun Yat-Sen University, Guangzhou (China)

    2015-06-15

    Highlights: • The k-ε based DES model is used in the nuclear containment simulation. • The comparison of results between different turbulent models is obtained. • The superiority of DES models is analyzed. • The computational efficiency with the DES turbulence models is explained. - Abstract: Different species of gases would be released into the containment and cause unpredicted disasters during the nuclear severe accidents. It is important to accurately predict the transportation and stratification phenomena of these gas mixtures. CFD simulations of these thermal hydraulic issues in nuclear containment are investigated in this paper. The main work is to study the influence of turbulence model on the calculation of gas transportation and heat transfer. The k-ε based DES and other frequently used turbulence models are used in the steam and helium release simulation in THAI series experiment. This paper will show the superiority of the DES turbulence model in terms of computational efficiency and accuracy with the experimental results, and analyze the necessities of DES model to simulate the large-scale containment flows with both laminar and turbulence regions.

  9. Simulation of power excursions - Osiris reactor; Simulation des excursions de puissance - pile Osiris

    Energy Technology Data Exchange (ETDEWEB)

    Pascouet, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    Following the experimental work accomplished in the U.S.A. on Borax 1 and SPERT 1 and the accident of SL 1, the 'Commissariat a l'Energie Atomique' started a research program about the safety of its own swimming Pool reactors, with regard to power excursions. The first research work led to the design of programmed explosive charges, adapted to the simulation of a power excursion. This report describes the application of these methods to the investigation of Osiris safety. (author) [French] A la suite des essais effectues aux U.S.A. sur BORAX 1 et SPERT 1 et de l'accident survenu a SL 1, le Commissariat a l'Energie Atomique a lance un programme d'etudes sur la surete de ses reacteurs piscines vis-a-vis des excursions de puissance. Les premieres etudes ont abouti A la mise au point de charges programmees capables de simuler une excursion de puissance. On trouvera dans le present rapport l'application de ces methodes a l'etude de la surete d'OSIRIS. (auteur)

  10. Modelling and simulations in hot deformation of steels

    International Nuclear Information System (INIS)

    Cabrera, J.M.

    2002-01-01

    Traditionally, hot forming has been employed to provide shape to metals. Nowadays, however, hot working not only produces the desired geometry, but also the mechanical characteristics required. An understanding of the thermomechanical behaviour of metals, and particularly steels, is essential in the simulation and control of the hot forming operations. Moreover, a right prediction of the final properties needs from accurate descriptions of the microstructural features occurring during the shaping step. For this purpose, the determination of constitutive equations describing the stress σ - strain ε relationships at a given strain rate ε, temperature T and initial microstructure, is a useful task. In this sense, computer simulations of hot working processes proportionate a benchmark to engineers and researchers and allow decreasing the cost of developing products and processes. With regard to the prediction of the final microstructure, the simulation of the hot plastic deformation usually gives unsatisfactory results. This is due to the inadequate constitutive equations employed by the conventional and commercial software available to describe the hot flow behaviour. There are scarce models which couple the typical hot working variables (temperature, strain and strain rate) with microstructural characteristics such as grain size. In this review work is presented how the latter limitation can be overcome by using physical-based constitutive equations, some of which have been partially developed by the present authors, where account of the interaction between microstructure and processing variables is taken. Moreover, a practical derivation of the latter expressions on an AISI-304 steel is presented. To conclude, some examples of industrial applications of the latter approach are also presented. Copyright (2002) AD-TECH - International Foundation for the Advancement of Technology Ltd

  11. Corrosion of construction steel in pore simulated solution

    International Nuclear Information System (INIS)

    Valdes, Matias; Vasquez, Marcela

    2004-01-01

    The corrosion of steel for reinforcing reinforced cement structures is a common problem particularly in structures that are exposed to a marine environment. Loosened masonry originating by the diametrical stress that iron oxides place on the cement is not unusual. These situations involve risk to people and goods and make it necessary to repair the structure to prolong its useful service life. Some preliminary results are presented from the reproduction of the corrosive process with the use of a solution that simulates the chemical surroundings in the concrete pores. These results will help to evaluate the incidence of contaminants (CO 2 , chloride ions), inhibitors and coatings, among others, in the following stages by conveniently adjusting the solution's composition. The composition of the chosen solution is: 0.01 mol NaOH - 0.002 mol/l Ca(OH) 2 . The effect was evaluated of a passive film generated on the surface of the steel of the reinforcements at 100 mV for 14 minutes and for 12 hours. This potential corresponds to the passive region, as determined by recording tests with cyclic volt amperometry and in accordance with the Pourbaix diagram for steel. The corrosion current was defined by recording the resistance to polarization using different electrochemical methods: potential sweep, potentiostatic jump and sweep electrochemical impedance. The results show that neither of the two times selected are enough to generate the metal's passive state and that the potential of 100 mV used to generate the passive film may be too low to produce a compact and long lasting layer, considering that the passive zone interval comes to 700 mV, according to the volt amperometry readings (CW)

  12. Weldability prediction of high strength steel S960QL after weld thermal cycle simulation

    Directory of Open Access Journals (Sweden)

    M. Dunđer

    2014-10-01

    Full Text Available This paper presents weld thermal cycle simulation of high strength steel S960QL, and describes influence of cooling time t8/5 on hardness and impact toughness of weld thermal cycle simulated specimens. Furthermore, it presents analysis of characteristic fractions done by electron scanning microscope which can contribute to determination of welding parameters for S960QL steel.

  13. Thermal fatigue of a 304L austenitic stainless steel: simulation of the initiation and of the propagation of the short cracks in isothermal and aniso-thermal fatigue; Fatigue thermique d'un acier inoxydable austenitique 304L: simulation de l'amorcage et de la croissance des fissures courtes en fatigue isotherme et anisotherme

    Energy Technology Data Exchange (ETDEWEB)

    Haddar, N

    2003-04-01

    The elbow pipes of thermal plants cooling systems are submitted to thermal variations of short range and of variable frequency. These variations bound to temperature changes of the fluids present a risk of cracks and leakages. In order to solve this problem, EDF has started the 'CRECO RNE 808' plan: 'thermal fatigue of 304L austenitic stainless steels' to study experimentally on a volume part, the initiation and the beginning of the propagation of cracks in thermal fatigue on austenitic stainless steels. The aim of this study is more particularly to compare the behaviour and the damage of the material in mechanic-thermal fatigue (cycling in temperature and cycling in deformation) and in isothermal fatigue (the utmost conditions have been determined by EDF for the metal: Tmax = 165 degrees C and Tmin = 90 degrees C; the frequency of the thermal variations can reach a Hertz). A lot of experimental results are given. A model of lifetime is introduced and validated. (O.M.)

  14. Reheat cracking in austenitic stainless steels; Fissuration en relaxation des aciers inoxydables austenitiques

    Energy Technology Data Exchange (ETDEWEB)

    Auzoux, Q.; Allais, L. [CEA Saclay, Dept. des Materiaux pour le Nucleaire, DMN, 91 - Gif sur Yvette (France); Pineau, A.; Gourgues, A.F. [Centre des Materiaux Pierre-Marie Fourt UMR CNRS 7633, 91 - Evry (France)

    2002-07-01

    Intergranular cracking can occur in heat-affected zones (HAZs) of austenitic stainless steel welded joints when reheated in the temperature range from 500 to 700 deg C. At this temperature, residual stresses due to welding relax by creep flow. HAZ may not sustain this small strain if its microstructure has been sufficiently altered during welding. In order to precise which particular microstructure alteration causes such an intergranular embrittlement, type 316L(N) HAZs were examined by transmission electron microscopy. A marked increase in the dislocation density, due to plastic strain during the welding process, was revealed, which caused an increase in Vickers hardness. Type 316L(N) HAZ were then simulated by the following thermal-mechanical process: annealing treatment and work hardening (pre-strain). Creep rupture tests on smooth specimens were also carried out at 600 deg C on both base metal and simulated HAZ. Pre-straining increased creep strength but reduced ductility. Slow strain rate tests on CT specimens confirmed this trend as well as did relaxation tests on CT specimens, which led to intergranular crack propagation in the pre-strained material only. Metallography and fractography showed no qualitative difference between base metal and HAZs in the creep cavitation around intergranular carbides. Although quantitative study of damage development is not achieved yet, experiments suggest that uniaxial creep strain smaller than one percent could lead to cavity nucleation when the material is pre-strained. Pre-strain as well as stress triaxiality reduce therefore creep ductility and enhance the reheat cracking risk. (authors)

  15. Creep Rupture of the Simulated HAZ of T92 Steel Compared to that of a T91 Steel

    Directory of Open Access Journals (Sweden)

    Yu-Quan Peng

    2017-02-01

    Full Text Available The increased thermal efficiency of fossil power plants calls for the development of advanced creep-resistant alloy steels like T92. In this study, microstructures found in the heat-affected zone (HAZ of a T92 steel weld were simulated to evaluate their creep-rupture-life at elevated temperatures. An infrared heating system was used to heat the samples to 860 °C (around AC1, 900 °C (slightly below AC3, and 940 °C (moderately above AC3 for one minute, before cooling to room temperature. The simulated specimens were then subjected to a conventional post-weld heat treatment (PWHT at 750 °C for two hours, where both the 900 °C and 940 °C simulated specimens had fine grain sizes. In the as-treated condition, the 900 °C simulated specimen consisted of fine lath martensite, ferrite subgrains, and undissolved carbides, while residual carbides and fresh martensite were found in the 940 °C simulated specimen. The results of short-term creep tests indicated that the creep resistance of the 900 °C and 940 °C simulated specimens was poorer than that of the 860 °C simulated specimens and the base metal. Moreover, simulated T92 steel samples had higher creep strength than the T91 counterpart specimens.

  16. Creep Rupture of the Simulated HAZ of T92 Steel Compared to that of a T91 Steel.

    Science.gov (United States)

    Peng, Yu-Quan; Chen, Tai-Cheng; Chung, Tien-Jung; Jeng, Sheng-Long; Huang, Rong-Tan; Tsay, Leu-Wen

    2017-02-08

    The increased thermal efficiency of fossil power plants calls for the development of advanced creep-resistant alloy steels like T92. In this study, microstructures found in the heat-affected zone (HAZ) of a T92 steel weld were simulated to evaluate their creep-rupture-life at elevated temperatures. An infrared heating system was used to heat the samples to 860 °C (around A C1 ), 900 °C (slightly below A C3 ), and 940 °C (moderately above A C3 ) for one minute, before cooling to room temperature. The simulated specimens were then subjected to a conventional post-weld heat treatment (PWHT) at 750 °C for two hours, where both the 900 °C and 940 °C simulated specimens had fine grain sizes. In the as-treated condition, the 900 °C simulated specimen consisted of fine lath martensite, ferrite subgrains, and undissolved carbides, while residual carbides and fresh martensite were found in the 940 °C simulated specimen. The results of short-term creep tests indicated that the creep resistance of the 900 °C and 940 °C simulated specimens was poorer than that of the 860 °C simulated specimens and the base metal. Moreover, simulated T92 steel samples had higher creep strength than the T91 counterpart specimens.

  17. Etude par simulation hil des performances d'un statcom pour la ...

    African Journals Online (AJOL)

    Ce travail présente l'étude par simulation Hardware In the Loop (HIL) des performances d'un STATCOM pour la stabilisation de la tension délivrée par une génératrice asynchrone triphasée auto excitée dans un réseau autonome. Nous avons combiné l'utilisation du logiciel de simulation LABVIEW et la carte ARDUINO ...

  18. When to use discrete event simulation (DES) for the economic evaluation of health technologies? A review and critique of the costs and benefits of DES.

    Science.gov (United States)

    Karnon, Jonathan; Haji Ali Afzali, Hossein

    2014-06-01

    Modelling in economic evaluation is an unavoidable fact of life. Cohort-based state transition models are most common, though discrete event simulation (DES) is increasingly being used to implement more complex model structures. The benefits of DES relate to the greater flexibility around the implementation and population of complex models, which may provide more accurate or valid estimates of the incremental costs and benefits of alternative health technologies. The costs of DES relate to the time and expertise required to implement and review complex models, when perhaps a simpler model would suffice. The costs are not borne solely by the analyst, but also by reviewers. In particular, modelled economic evaluations are often submitted to support reimbursement decisions for new technologies, for which detailed model reviews are generally undertaken on behalf of the funding body. This paper reports the results from a review of published DES-based economic evaluations. Factors underlying the use of DES were defined, and the characteristics of applied models were considered, to inform options for assessing the potential benefits of DES in relation to each factor. Four broad factors underlying the use of DES were identified: baseline heterogeneity, continuous disease markers, time varying event rates, and the influence of prior events on subsequent event rates. If relevant, individual-level data are available, representation of the four factors is likely to improve model validity, and it is possible to assess the importance of their representation in individual cases. A thorough model performance evaluation is required to overcome the costs of DES from the users' perspective, but few of the reviewed DES models reported such a process. More generally, further direct, empirical comparisons of complex models with simpler models would better inform the benefits of DES to implement more complex models, and the circumstances in which such benefits are most likely.

  19. Mathematical modelling and TMCP simulation for optimisation of steel behaviour

    International Nuclear Information System (INIS)

    Siwecki, T.

    2001-01-01

    Physically based mathematical models for prediction of steel behaviour and microstructure evolution in connection with thermal and thermomechanical controlled processing (TMCP) development in Swedish Institute for Metals Research are discussed. The models can be used for computer predictions of recrystallization and grain growth of austenite after deformation, precipitation or dissolution of microalloying carbonitride in austenite, flow stress during hot working, phase transformation behaviour during accelerated cooling as well as the final microstructure and mechanical properties. The database, which contains information about steel behaviour for a large number of HSLA steels, is also presented. Optimization of TMCP parameters for improving the properties of the steel are discussed in relation to the microstructure and mechanical properties. The effect of TMCP parameters (reheating temperature, rolling schedules and finish rolling temperature as well as accelerated control cooling) on steel properties was studied in laboratory scale. (author)

  20. Numerical simulation of convection and inclusion distribution during solidification in a heavy steel ingot

    International Nuclear Information System (INIS)

    Lin, Rui; Shen, Houfa

    2015-01-01

    Inclusions content in the steel ingot is an important index for homogeneity, and it becomes more serious for heavy steel ingots which are used for major equipment. However, knowledge about the formation of inclusion in steel ingot is limited, and modeling of inclusion distribution is still challenging, so it is of great significance to research the behavior of inclusion. In this paper, fluid flow during solidification is numerically simulated based on the equilibrium equations of mass, momentum and energy, and then inclusion distribution is modeled according to the Lagrangian Stokes trajectory method. The Results show that the inclusion distribution in the steel ingot is influenced by the flow pattern which is affected by the solidification pattern. Therefore, inclusion distribution could be controlled by the solidification front with the optimization of heat transfer condition such as the hot top design of steel ingot for the high quality steel production. (paper)

  1. Numerical simulation of water flow in lysimeters; Numerische Simulation des Wasserflusses in Lysimetern

    Energy Technology Data Exchange (ETDEWEB)

    Honisch, M.; Klotz, D. [GSF - Forschungszentrum fuer Umwelt und Gesundheit GmbH, Neuherberg (Germany). Inst. fuer Hydrologie

    1999-02-01

    A small-scale lysimeter plant on the premises of GSF has been dedicated to the study of water movement in sediments of Quaternary and Tertiary origin. The purpose of the present study was to describe water transport and non-reactive transport in the lysimeters under transient conditions and test the suitability of the numerical simulation programme Hydrus-2D for the unsaturated zone. The hydraulic characteristics and dispersiveness parameters were derived from earlier studies. The validity of these values was determined on the basis of a tracer experiment using the ideal tracer tritium water. [Deutsch] Zur Charakterisierung der Wasserbewegung in Sedimenten quartaeren und tertiaeren Ursprungs wird auf dem Gelaende der GSF eine Kleinlysimeteranlage betrieben. Ziel der vorliegenden Untersuchung war es, den Wasserfluss und nicht-reaktiven Transport in den Saeulen unter transienten Bedingungen zu beschreiben und hierbei die Eignung des numerischen Simulationsprogramms Hydrus-2D fuer die ungesaettigte Zone zu ueberpruefen. Die hydraulischen Kenngroessen und Dispersivitaetsparameter waren aus frueheren Untersuchungen abzuleiten. Die offene Frage hinsichtlich der Validitaet dieser Werte sollte auf der Grundlage eines Tracerexperiments mit tritiiertem Wasser als idealem Tracer ueberprueft werden. (orig.)

  2. Image based EFIT simulation for nondestructive ultrasonic testing of austenitic steel

    International Nuclear Information System (INIS)

    Nakahata, Kazuyuki; Hirose, Sohichi; Schubert, Frank; Koehler, Bernd

    2009-01-01

    The ultrasonic testing (UT) of an austenitic steel with welds is difficult due to the acoustic anisotropy and local heterogeneity. The ultrasonic wave in the austenitic steel is skewed along crystallographic directions and scattered by weld boundaries. For reliable UT, a straightforward simulation tool to predict the wave propagation is desired. Here a combined method of elastodynamic finite integration technique (EFIT) and digital image processing is developed as a wave simulation tool for UT. The EFIT is a grid-based explicit numerical method and easily treats different boundary conditions which are essential to model wave propagation in heterogeneous materials. In this study, the EFIT formulation in anisotropic and heterogeneous materials is briefly described and an example of a two dimensional simulation of a phased array UT in an austenitic steel bar is demonstrated. In our simulation, a picture of the surface of the steel bar with a V-groove weld is scanned and fed into the image based EFIT modeling. (author)

  3. An adaptive DES smodel that allows wall-resolved eddy simulation

    International Nuclear Information System (INIS)

    Yin, Zifei; Durbin, Paul A.

    2016-01-01

    Highlights: • A Detached Eddy Simulation model that mimics dynamic Smagorinsky formulation. • Adaptivity of model allows wall resolved eddy simulation on sufficient grids. • Ability to simulate natural and bypass transition is tested. - Abstract: A modification to the Adaptive-DES method of Yin et al. (2015) is proposed to improve its near-wall behavior. The modification is to the function (C_l_i_m) that imposes a lower limit on the dynamically evaluated coefficient (C_D_E_S). The modification allows Adaptive-DES to converge to wall-resolved eddy simulation, when grid resolution supports it. On coarse grids, or at high Reynolds number, it reverts to shielded DES — that is to DDES. The new formulation predicts results closer to wall-resolved LES than the previous formulation. It provides an ability to simulate transition: it is tested in both orderly and bypass transition. In fully turbulent, attached flow, the modification has little effect. Any improvement in predictions stem from better near-wall behavior of the adaptive method.

  4. Thermal fatigue cracking of austenitic stainless steels; Fissuration en fatigue thermique des aciers inoxydables austenitiques

    Energy Technology Data Exchange (ETDEWEB)

    Fissolo, A

    2001-07-01

    This report deals with the thermal fatigue cracking of austenitic stainless steels as AISI 316 LN and 304 L. Such damage has been clearly observed for some components used in Fast Breeder reactors (FBR) and Pressure Water Reactor (PWR). In order to investigate thermal fatigue, quasi-structural specimen have been used. In this frame, facilities enforcing temperature variations similar to those found under the operation conditions have been progressively developed. As for components, loading results from impeded dilatation. In the SPLASH facility, the purpose was to establish accurate crack initiation conditions in order to check the relevance of the usual component design methodology. The tested specimen is continuously heated by the passage of an electrical DC current, and submitted to cyclic thermal down shock (up to 1000 deg C/s) by means of periodical spraying of water on two opposite specimen faces. The number of cycles to crack initiation N{sub i} is deduced from periodic examinations of the quenched surfaces, by means of optical microscopy. It is considered that initiation occurs when at least one 50{mu}m to 150{open_square}m long crack is observed. Additional SPLASH tests were performed for N >> N{sub i}, with a view to investigate the evolution of a surface multiple cracking network with the number of cycles N. The CYTHIA test was mainly developed for the purpose of assessing crack growth dynamics of one isolated crack in thermal fatigue conditions. Specimens consist of thick walled tubes with a 1 mm circular groove is spark-machined at the specimen centre. During the test, the external wall of the tube is periodically heated by using a HF induction coil (1 MHz), while its internal wall is permanently cooled by flowing water. Total crack growth is derived from post-mortem examinations, whereby the thermal fatigue final rupture surface is oxidized at the end of the test. The specimen is broken afterwards under mechanical fatigue at room temperature. All the

  5. Data-driven simulation methodology using DES 4-layer architecture

    Directory of Open Access Journals (Sweden)

    Aida Saez

    2016-05-01

    Full Text Available In this study, we present a methodology to build data-driven simulation models of manufacturing plants. We go further than other research proposals and we suggest focusing simulation model development under a 4-layer architecture (network, logic, database and visual reality. The Network layer includes system infrastructure. The Logic layer covers operations planning and control system, and material handling equipment system. The Database holds all the information needed to perform the simulation, the results used to analyze and the values that the Logic layer is using to manage the Plant. Finally, the Visual Reality displays an augmented reality system including not only the machinery and the movement but also blackboards and other Andon elements. This architecture provides numerous advantages as helps to build a simulation model that consistently considers the internal logistics, in a very flexible way.

  6. Fragilisation par le zinc liquide des aciers haute résistance pour l'automobile Liquid zinc embrittlement of high strength automotive steels

    Directory of Open Access Journals (Sweden)

    Frappier Renaud

    2013-11-01

    Full Text Available Cette étude présente les investigations menées sur la fragilisation par le zinc liquide d'un acier électro-zingué. La caractérisation mécanique par essais de traction à haute température montre un important puits de ductilité entre environ 700 ∘C et environ 950 ∘C. L'observation au MEB des éprouvettes de traction indique que, dans la gamme de température observée pour laquelle il y a fragilisation, on a mouillage intergranulaire des joints de grains de l'acier à l'interface acier/revêtement par des films de Zn. La corrélation entre mouillage intergranulaire thermiquement activé d'une part, et propagation de fissure lors du chargement d'autre part, est discutée. This study deals with liquid zinc embrittlement for electro-galvanized steel. Mechanical characterization by high temperature tensile tests shows a drastic loss of ductility between 700 ∘C and 950 ∘C. SEM investigations show that steel grain boundaries under the steel/coating interface are penetrated by a liquid Zn channel, only in the temperature range of embrittlement. A correlation can be drawn between i thermal activated-grain boundary wetting and ii crack propagation in presence of external stress.

  7. Microstructure and properties of the heat-resistant chromium steel P91; Gefuege und Eigenschaften des warmfesten Chromstahls P91

    Energy Technology Data Exchange (ETDEWEB)

    Kohlar, Stefanie

    2017-07-01

    The heat-resistant chromium steel X10CrMoVNb9-1 specified as P91 is based on its good properties at high temperatures and high mechanical Stresses as a potential material for use as reactor pressure vessel material in fourth generation nuclear reactors. Subject of this work was the characterization of the microstructure and mechanical properties of this material. For this purpose it was metallographically examined and technically important characteristic values were determined. Different etching methods and imaging techniques were used, with the method of oxalic acid etching newly applied to this material providing meaningful results. Tensile tests, hardness tests and notched bar impact tests provided mechanical-technological characteristics. The fracture mechanical behavior was determined by means of fracture mechanics tests on bending and compact tensile tests. The main focus was on the investigation of the applicability of the evaluation methods described in standards ASTM 1921 and ASTM 1820 for low alloy steels. The investigations showed that the P91 is expected to have a homogeneous martensitic structure consisting of annealed martensite with embedded carbides and carbonitrides. The location and size of the found carbides could be represented by the process of oxalic acid etching newly applied to this material. The mechanical-technological tests showed a good strength and toughness behavior typical for tempered steel. The application of the linear-elastic fracture mechanics and the yielding fracture mechanics made it possible to determine a reference temperature according to ASTM 1921-08a, but also showed that the evaluation methods and geometries described for this high-alloy steel in ASTM 1820-08 do not lead to valid material characteristics. In order to determine the suitability of this material for nuclear applications, the irradiation and creep behavior of the P91 should be characterized more precisely in further investigations. [German] Der als P91

  8. Steel

    International Nuclear Information System (INIS)

    Zorev, N.N.; Astafiev, A.A.; Loboda, A.S.; Savukov, V.P.; Runov, A.E.; Belov, V.A.; Sobolev, J.V.; Sobolev, V.V.; Pavlov, N.M.; Paton, B.E.

    1977-01-01

    Steels also containing Al, N and arsenic, are suitable for the construction of large components for high-power nuclear reactors due to their good mechanical properties such as good through-hardening, sufficiently low brittleness conversion temperature and slight displacement of the latter with neutron irradiation. Defined steels and their properties are described. (IHOE) [de

  9. Stress relief cracking by relaxation in austenitic stainless steels welded junctions; Fissuration differee par relaxation des jonctions soudes en aciers inoxydables austenitiques

    Energy Technology Data Exchange (ETDEWEB)

    Allais, L.; Auzoux, Q.; Chabaud-Reytier, M

    2003-07-01

    During service at high temperature (450 to 650 C), austenitic stainless steels are well known to present a risk of cracking near the welded junctions for times under the service life. This intergranular cracking in affected zones has been identified on titanium stabilized steels and is known as relief cracking by relaxation or reheat cracking. In order to control this cracking of welded junctions on titanium stabilized stainless steel AISI 321, a simulation of the affected zone has been realized. The results have been extended to non stabilized steels. (A.L.B.)

  10. Numerical simulation of continuous cooling of a low alloy steel to predict microstructure and hardness

    International Nuclear Information System (INIS)

    Kakhki, M Eshraghi; Kermanpur, A; Golozar, M A

    2009-01-01

    In this work, a numerical model was developed to simulate the continuous cooling of a low alloy steel. In order to simulate the kinetics of diffusional phase transformations, the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation and additivity rule were employed, while a new model was applied for martensitic transformation. In addition, a novel approach was applied for computing the actual phase fractions in the multiphase steel. Effects of latent heat release during phase transformations, temperature and phase fractions on the variation of thermo-physical properties were considered. The developed numerical model was applied to simulate the cooling process during the Jominy end quench test as well as the quenching of a steel gear in water and oil. In this respect, precise models were used to simulate the complex boundary conditions in the Jominy test and a stainless steel probe was used for determining the heat transfer coefficients of quenching media by an inverse method. The present model was validated against cooling curve measurements, metallographic analysis and hardness tests. Good agreement was found between the experimental and simulation results. This model is able to simulate the continuous cooling and kinetics of phase transformation and to predict the final distribution of microstructures and hardness in low alloy steels

  11. Microstructural characterization and model of hardening for the irradiated austenitic stainless steels of the internals of pressurized water reactors; Caracterisation microstructurale et modelisation du durcissement des aciers austenitiques irradies des structures internes des reacteurs a eau pressurisee

    Energy Technology Data Exchange (ETDEWEB)

    Pokor, C

    2003-07-01

    The core internals of Pressurized Water Reactors (PWR) are composed of SA 304 stainless steel plates and CW 316 stainless steel bolts. These internals undergo a neutron flux at a temperature between 280 deg C and 380 deg C which modifies their mechanical properties. These modifications are due to the changes in the microstructure of these materials under irradiation which depend on flux, dose and irradiation temperature. We have studied, by Transmission Electron Microscopy, the microstructure of stainless steels SA 304, CW 316 and CW 316Ti irradiated in a mixed flux reactor (OSIRIS at 330 deg C between 0,8 dpa et 3,4 dpa) and in a fast breeder reactor at 330 deg C (BOR-60) up to doses of 40 dpa. Moreover, samples have been irradiated at 375 deg C in a fast breeder reactor (EBR-II) up to doses of 10 dpa. The microstructure of the irradiated stainless steels consists in faulted Frank dislocation loops in the [111] planes of austenitic, with a Burgers vector of [111]. It is possible to find some voids in the solution annealed samples irradiated at 375 deg C. The evolution of the dislocations loops and voids has been simulated with a 'cluster dynamic' model. The fit of the model parameters has allowed us to have a quantitative description of our experimental results. This description of the microstructure after irradiation was coupled together with a hardening model by Frank loops that has permitted us to make a quantitative description of the hardening of SA 304, CW 316 and CW 316Ti stainless steels after irradiation at a certain dose, flux and temperature. The irradiation doses studied grow up to 90 dpa, dose of the end of life of PWR internals. (author)

  12. Simulations multidomaines des écoulements en milieu poreux

    OpenAIRE

    MARTIN , Vincent

    2004-01-01

    Jury Chavent Guy (president) Loth Laurent Pironneau Olivier (rapporteur) Roberts Jean E. (directrice) Russell Thomas F. (rapporteur) Weis Pierre; This thesis is mainly concerned with the multidomain simulations of flow in porous media. Three different themes are considered. First, we study a domain decomposition method with non-matching meshes using Robin type interface conditions, for the mixed finite elements. Second, this method is implemented in parallel using the parallel system OcamlP3l...

  13. Geoscience Diversity Experiential Simulations (GeoDES) Workshop Report

    Science.gov (United States)

    Houlton, H. R.; Chen, J.; Brown, B.; Samuels, D.; Brinkworth, C.

    2017-12-01

    The geosciences have to solve increasingly complex problems relating to earth and society, as resources become limited, natural hazards and changes in climate impact larger communities, and as people interacting with Earth become more interconnected. However, the profession has dismally low representation from geoscientists who are from diverse racial, ethnic, or socioeconomic backgrounds, as well as women in leadership roles. This underrepresentation also includes individuals whose gender identity/expression is non-binary or gender-conforming, or those who have physical, cognitive, or emotional disabilities. This lack of diversity ultimately impacts our profession's ability to produce our best science and work with the communities that we strive to protect and serve as stewards of the earth. As part of the NSF GOLD solicitation, we developed a project (Geoscience Diversity Experiential Simulations) to train 30 faculty and administrators to be "champions for diversity" and combat the hostile climates in geoscience departments. We hosted a 3-day workshop in November that used virtual simulations to give participants experience in building the skills to react to situations regarding bias, discrimination, microaggressions, or bullying often cited in geoscience culture. Participants interacted with avatars on screen, who responded to participants' actions and choices, given certain scenarios. The scenarios are framed within a geoscience perspective; we integrated qualitative interview data from informants who experienced inequitable judgement, bias, discrimination, or harassment during their geoscience careers. The simulations gave learners a safe environment to practice and build self-efficacy in how to professionally and productively engage peers in difficult conversations. In addition, we obtained pre-workshop survey data about participants' understanding regarding Diversity, Equity, and Inclusion practices, as well as observation data of participants' responses

  14. simulation du climat futur et des rendements agricoles en region

    African Journals Online (AJOL)

    ACSS

    2017, African Crop Science Society. African Crop Science Journal by African Crop Science Society is licensed under a Creative Commons Attribution 3.0 Uganda License. Based on a work at www.ajol.info/ and www.bioline.org.br/cs. DOI: http://dx.doi.org/10.4314/acsj.v25i4.2. SIMULATION DU CLIMAT FUTUR ET DES ...

  15. Simulation of Thermo-viscoplastic Behaviors for AISI 4140 Steel

    Science.gov (United States)

    Li, Hong-Bin; Feng, Yun-Li

    2016-04-01

    The thermo-viscoplastic behaviors of AISI 4140 steel are investigated over wide ranges of strain rate and deformation temperature by isothermal compression tests. Based on the experimental results, a unified viscoplastic constitutive model is proposed to describe the hot compressive deformation behaviors of the studied steel. In order to reasonably evaluate the work hardening behaviors, a strain hardening material constant (h0) is expressed as a function of deformation temperature and strain rate in the proposed constitutive model. Also, the sensitivity of initial value of internal variable s to the deformation temperature is discussed. Furthermore, it is found that the initial value of internal variable s can be expressed as a linear function of deformation temperature. Comparisons between the measured and predicted results confirm that the proposed constitutive model can give an accurate and precise estimate of the inelastic stress-strain relationships for the studied high-strength steel.

  16. General and Localized corrosion of Austenitic and Borated Stainless Steels in Simulated Concentrated Ground Waters

    International Nuclear Information System (INIS)

    Fix, D.; Estill, J.; Wong, L.; Rebak, R.

    2004-01-01

    Boron containing stainless steels are used in the nuclear industry for applications such as spent fuel storage, control rods and shielding. It was of interest to compare the corrosion resistance of three borated stainless steels with standard austenitic alloy materials such as type 304 and 316 stainless steels. Tests were conducted in three simulated concentrated ground waters at 90 C. Results show that the borated stainless were less resistant to corrosion than the witness austenitic materials. An acidic concentrated ground water was more aggressive than an alkaline concentrated ground water

  17. Steel heat treating: mathematical modelling and numerical simulation of a problem arising in the automotive industry

    Directory of Open Access Journals (Sweden)

    Jose Manuel Diaz Moreno

    2017-12-01

    Full Text Available We describe a mathematical model for the industrial heating and cooling processes of a steel workpiece representing the steering rack of an automobile. The goal of steel heat treating is to provide a hardened surface on critical parts of the workpiece while keeping the rest soft and ductile in order to reduce fatigue. The high hardness is due to the phase transformation of steel accompanying the rapid cooling. This work takes into account both heating-cooling stage and viscoplastic model. Once the general mathematical formulation is derived, we can perform some numerical simulations.

  18. Méthodes particulaires pour la simulation des sillages tridimensionnels

    OpenAIRE

    Poncet , Philippe

    2001-01-01

    This work is devoted to the development of a particle method in order to solve the three-dimensional Navier-Stokes equations. Since the Biot-Savart law is by far too expensive in three dimensions, an hybrid grid-particle method is chosen. This method is then applied to simulations and control of three-dimensional cylinder wakes.The first part deals with the numerical method itself. We begin with a presentation of the lagrangian model and the methodology used to compute the velocity field, whi...

  19. The numerical simulation of Lamb wave propagation in laser welding of stainless steel

    Science.gov (United States)

    Zhang, Bo; Liu, Fang; Liu, Chang; Li, Jingming; Zhang, Baojun; Zhou, Qingxiang; Han, Xiaohui; Zhao, Yang

    2017-12-01

    In order to explore the Lamb wave propagation in laser welding of stainless steel, the numerical simulation is used to show the feature of Lamb wave. In this paper, according to Lamb dispersion equation, excites the Lamb wave on the edge of thin stainless steel plate, and presents the reflection coefficient for quantizing the Lamb wave energy, the results show that the reflection coefficient is increased with the welding width increasing,

  20. Atmospheric Corrosion Behavior and Mechanism of a Ni-Advanced Weathering Steel in Simulated Tropical Marine Environment

    Science.gov (United States)

    Wu, Wei; Zeng, Zhongping; Cheng, Xuequn; Li, Xiaogang; Liu, Bo

    2017-12-01

    Corrosion behavior of Ni-advanced weathering steel, as well as carbon steel and conventional weathering steel, in a simulated tropical marine atmosphere was studied by field exposure and indoor simulation tests. Meanwhile, morphology and composition of corrosion products formed on the exposed steels were surveyed through scanning electron microscopy, energy-dispersive x-ray spectroscopy and x-ray diffraction. Results indicated that the additive Ni in weathering steel played an important role during the corrosion process, which took part in the formation of corrosion products, enriched in the inner rust layer and promoted the transformation from loose γ-FeOOH to dense α-FeOOH. As a result, the main aggressive ion, i.e., Cl-, was effectively separated in the outer rust layer which leads to the lowest corrosion rate among these tested steels. Thus, the resistance of Ni-advanced weathering steel to atmospheric corrosion was significantly improved in a simulated tropical marine environment.

  1. Austenite grain growth and microstructure control in simulated heat affected zones of microalloyed HSLA steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei [Department of Machine Tools and Factory Management, Technical University of Berlin, Pascalstraße 8 – 9, 10587, Berlin (Germany); Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205, Berlin (Germany); Kannengiesser, Thomas [Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205, Berlin (Germany); Institute of Materials and Joining Technology, Otto von Guericke University Magdeburg, Universitetsplatz 2, 39106, Magdeburg (Germany)

    2014-09-08

    The roles of microalloying niobium, titanium and vanadium for controlling austenite grain growth, microstructure evolution and hardness were investigated at different simulated heat affected zones (HAZ) for high strength low alloy (HSLA) S690QL steel. High resolution FEG-SEM has been used to characterize fine bainitic ferrite, martensite and nanosized second phases at simulated coarse and fine grain HAZs. It was found that for Ti bearing steel (Ti/N ratio is 2) austenite grain had the slowest growth rate due to the presence of most stable TiN. The fine cuboidal particles promoted intragranular acicular ferrite (IGF) formation. Nb bearing steel exhibited relatively weaker grain growth retardation compared with titanium bearing steels and a mixed microstructure of bainite and martensite was present for all simulated HAZs. IGF existed at coarse grain HAZ of Ti+V bearing steel but it was totally replaced by bainite at fine grain HAZs. Hardness result was closely related to the morphology of bainitic ferrite, intragranular ferrite and second phases within ferrite. The microstructure and hardness results of different simulated HAZs were in good agreement with welded experimental results.

  2. Apports de la simulation multi-agents à l’étude des processus de diffusion

    Directory of Open Access Journals (Sweden)

    Eric Daudé

    2004-02-01

    Full Text Available Cet article présente les principaux apports d’une approche individu-centrée pour modéliser et simuler les processus de diffusion dans l’espace géographique. L’intérêt d’une telle approche est discuté au regard des limites d’une modélisation d'échelle macro-géographique traditionnellement employée pour décrire de tels phénomènes. L’équation logistique est présentée comme un exemple représentatif de cette catégorie de modèle. Les modèles de simulation à base d’agents représentent une alternative possible à une approche macro-géographique des phénomènes de diffusion. Associés aux théories de l’auto-organisation, on postule que les phénomènes observés à un certain niveau sont le résultat des nombreuses interactions qui se produisent à un ou plusieurs niveaux inférieurs. En tant qu’outil de simulation prédisposé à l’analyse de telles dynamiques, les systèmes multi-agents sont brièvement présentés. Cet article se termine par une application, la modélisation et la simulation de la diffusion d’une innovation agricole (le modèle d'Hägerstrand revisité.

  3. Electrochemical and corrosion properties of carbon steel in simulated geological disposal environments

    International Nuclear Information System (INIS)

    Sugimoto, Katsuhisa

    2011-01-01

    This paper reviews electrochemical and corrosion studies on the application of carbon steel to an overpack container, which is used for the geological disposal of radioactive wastes. Deaerated alkaline Na 2 SO 4 -NaHCO 3 - NaCl solutions and bentonite soaked with the solutions are used as simulated geological disposal environments. Electrochemical studies show the corrosion of the steel in an early stage is the activation control. Corrosion rates are controlled by the composition of the solutions, alloying elements, and the structure of the steel. The rates decrease with time due to the formation of FeCO 3 (siderite) film on the steel. Immersion corrosion tests show general corrosion morphology. Average corrosion rates of long duration have been evaluated. Clear proofs of the initiation of localized corrosion, such as pitting, crevice corrosion, hydrogen embrittlement and stress-corrosion cracking, have not been reported. (author)

  4. Simulation of a Local Collision of SC Wall Using High Energy Absorbing Steel

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, H. K.; Chung, C. H.; Park, J.; Lee, J. W. [Dankook University, Yongin (Korea, Republic of); Kim, S. Y. [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2011-05-15

    Local damage evaluations for nuclear power plant(NPP) design are performed against turbine impact, tornado impact, airplane engine impact, etc., where turbine is a internal source of impact, whereas tornado and airplane engine are external sources of impact. The thickness of NPP wall structure is determined at initial design stage not to be penetrated by local impacts. This study investigated the local damage of NPP substructure against internal turbine impact. Simulation of local collisions of SC wall in NPP structure, which consists of two models: one using general steel and the other using high energy absorbing steel, were performed. The performance of SC wall using ductile high energy absorbing steel can be greatly improved on local collisions when compared with that of general steel

  5. Simulation of a Local Collision of SC Wall Using High Energy Absorbing Steel

    International Nuclear Information System (INIS)

    Yoo, H. K.; Chung, C. H.; Park, J.; Lee, J. W.; Kim, S. Y.

    2011-01-01

    Local damage evaluations for nuclear power plant(NPP) design are performed against turbine impact, tornado impact, airplane engine impact, etc., where turbine is a internal source of impact, whereas tornado and airplane engine are external sources of impact. The thickness of NPP wall structure is determined at initial design stage not to be penetrated by local impacts. This study investigated the local damage of NPP substructure against internal turbine impact. Simulation of local collisions of SC wall in NPP structure, which consists of two models: one using general steel and the other using high energy absorbing steel, were performed. The performance of SC wall using ductile high energy absorbing steel can be greatly improved on local collisions when compared with that of general steel

  6. Gas network simulations of the regional utility GVT; Gasnetzsimulation des Regionalgasversorgers GVT

    Energy Technology Data Exchange (ETDEWEB)

    Schacht, W. [Gasversorgung Thueringen GmbH (GVT), Erfurt (Germany)

    2000-07-01

    At the turn of the millenium, the German gas industry is faced with new challenges, e.g. the European single market, energy political boundary conditions, deregulation and increased competition. Flexibility, new marketing concepts and higher profitability are key concerns. Optimisation of gas supply can only be ensured by dynamic gas network simulation which also provide information on the current state of gas flow in the network. [German] Zum Beginn des neuen Jahrtausends steht die Erdgaswirtschaft in Deutschland vor voellig neuen Herausforderungen. Der EU-Binnenmarkt, die neuen energiepolitischen Rahmenbedingungen, die Oeffnung und Liberalisierung der Energiemaerkte und die damit im Zusammenhang stehende Verschaerfung des Gas-zu-Gas-Wettbewerbes zwingen zu einer hoeheren Flexibilitaet, zur Einfuehrung neuer Marketingkonzepte und zu einer weiteren Erhoehung der Rentabilitaet unserer Versorgungsunternehmen durch Nutzung von neuen oder noch nicht ausgeschoepften Kosteneinsparungspotentialen. Eine wichtige Voraussetzung fuer den Aufbau einer modernen Gasbezugsoptimierung ist die prozessbegleitende dynamische Gasnetzsimulation. Ausserdem setzen moderne Verfahren der Netzsteuerung derartige Kenntnisse ueber den aktuellen Stroemungszustand im Netz voraus. Mit den im Simulationssystem vorhandenen Zustandsbeobachtern koennen die gewonnenen Aussagen gestuetzt und praezisiert werden. Mit Blick auf die neue Marktordnung gewinnt die online Gasnetzsimulation noch zusaetzlich an Bedeutung. Aus der zeitlichen Entkopplung von Menge und Preis, der Durchleitung sowie der Speicherung und des effektiven Einsatzes von Spottmengen leiten sich voellig neue Aufgaben ab, die operativ nur mit Hilfe einer qualitativ neuen Leittechnik und einer online Gasnetzsimulation geloest werden koennen. Werden diese Aufgaben nicht adaequat geloest, steigt das wirtschaftliche Risiko eklatant an. (orig.)

  7. Work Hardening Behavior of 1020 Steel During Cold-Beating Simulation

    Science.gov (United States)

    CUI, Fengkui; LING, Yuanfei; XUE, Jinxue; LIU, Jia; LIU, Yuhui; LI, Yan

    2017-03-01

    The present research of cold-beating formation mainly focused on roller design and manufacture, kinematics, constitutive relation, metal flow law, thermo-mechanical coupling, surface micro-topography and microstructure evolution. However, the research on surface quality and performance of workpieces in the process of cold-beating is rare. Cold-beating simulation experiment of 1020 steel is conducted at room temperature and strain rates ranging from 2000 to 4000 s-1 base on the law of plastic forming. According to the experimental data, the model of strain hardening of 1020 steel is established, Scanning Electron Microscopy(SEM) is conducted, the mechanism of the work hardening of 1020 steel is clarified by analyzing microstructure variation of 1020 steel. It is found that the strain rate hardening effect of 1020 steel is stronger than the softening effect induced by increasing temperatures, the process of simulation cold-beating cause the grain shape of 1020 steel significant change and microstructure elongate significantly to form a fibrous tissue parallel to the direction of deformation, the higher strain rate, the more obvious grain refinement and the more hardening effect. Additionally, the change law of the work hardening rate is investigated, the relationship between dislocation density and strain, the relationship between work hardening rate and dislocation density is obtained. Results show that the change trend of the work hardening rate of 1020 steel is divided into two stages, the work hardening rate decreases dramatically in the first stage and slowly decreases in the second stage, finally tending toward zero. Dislocation density increases with increasing strain and strain rate, work hardening rate decreases with increasing dislocation density. The research results provide the basis for solving the problem of improving the surface quality and performance of workpieces under cold-beating formation of 1020 steel.

  8. Simulation Kinetics of Austenitic Phase Transformation in Ti+Nb Stabilized IF and Microalloyed Steels

    Science.gov (United States)

    Ghosh, Sumit; Dasharath, S. M.; Mula, Suhrit

    2018-05-01

    In the present study, the influence of cooling rates (low to ultrafast) on diffusion controlled and displacive transformation of Ti-Nb IF and microalloyed steels has been thoroughly investigated. Mechanisms of nucleation and formation of non-equiaxed ferrite morphologies (i.e., acicular ferrite and bainitic ferrite) have been analyzed in details. The continuous cooling transformation behavior has been studied in a thermomechanical simulator (Gleeble 3800) using the cooling rates of 1-150 °C/s. On the basis of the dilatometric analysis of each cooling rate, continuous cooling transformation (CCT) diagrams have been constructed for both the steels to correlate the microstructural features at each cooling rate in different critical zones. In the case of the IF steel, massive ferrite grains along with granular bainite structures have been developed at cooling rates > 120 °C/s. On the other hand, a mixture of lath bainitic and lath martensite structures has been formed at a cooling rate of 80 °C/s in the microalloyed steel. A strong dependence of the cooling rates and C content on the microstructures and mechanical properties has been established. The steel samples that were fast cooled to a mixture of bainite ferrite and martensite showed a significant improvement of impact toughness and hardness (157 J, for IF steel and 174 J for microalloyed steel) as compared to that of the as-received specimens (133 J for IF steel and 116 J for microalloyed steel). Thus, it can be concluded that the hardness and impact toughness properties are correlated well with the microstructural constituents as indicated by the CCT diagram. Transformation mechanisms and kinetics of austenitic transformation to different phase morphologies at various cooling rates have been discussed in details to correlate microstructural evolution and mechanical properties.

  9. Modeling and simulation of bus assem-bling process using DES/ABS approach

    Directory of Open Access Journals (Sweden)

    Pawel PAWLEWSKI

    2017-03-01

    Full Text Available This paper presents the results of the project, which goal is to analyze the production process capability after reengineering the assembly process due to expansion of a bus production plant. The verification of the designed work organization for the new configuration of workstations on new production hall is necessary. To solve these  problems authors propose a method based on mixing DES (Discrete Event Simulation and ABS (Agent Based Simulation approach. DES is using to model the main process – material flow (buses, ABS is using to model assembling operations of teams of  workers.One of obtained goal is to build a simulation model, which presents the new assembly line in the factory, taking into ac-count the arrangement of workstations and work teams in the new production hall as well as the transport between workstations. Second goal is to present work organization of work teams and division of individual workers’ labor (who belongs to a particular work team and performs operations on buses in a particular workstation in order to determine the best allocation of tasks and the optimum size of individual work teams. Proposed solution enables to determine the effect of assembly interferences on the work of particular work teams and the efficiency of the whole production system, to define the efficiency of the designed assembly lines and proposing changes aimed at the quality improvement of the created conception. 

  10. Interpretation of toughness tests performed on A533, grade B steel in the transition regime. Modelling and numerical analysis; Interpretation des essais de tenacite de l`acier A533, grade B dans le domaine de la transition fragile-ductile. Simulation numerique et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Eripret, C.

    1994-01-01

    Modelling the fracture behaviour of pressure vessel steels is of major importance for related structural integrity assessments. It is essential to understand how the micromechanisms control the transition between ductile and brittle fracture for predicting geometry effects on transition temperature. To meet this goal, a model has been developed at EDF/R and DD in the framework of local approach to fracture. Its experimental validation has been achieved by analysing toughness tests performed by AEA Technology for a pressure vessel steel in the transition regime. This large data base has evidenced the specimen thickness effects on toughness properties of the material, as well as influence of prior ductile crack growth. Predictions of the model have been compared with experiments, which shows that the transition curve K{sub 1C} = f (T) can be drawn from model predictions and compared with the RCCM or ASME design curve. Substantial safety margins have been exhibited. They are greater for thin specimens (10 mm) than for thicker specimens (230 mm). However, the transition curve in the upper transition region is still underestimated by the model (for temperatures higher than RTNDT + 50 deg C). Improvement should be made to account for important plasticity development and significant crack growth. (author). 30 figs., 10 tabs., 12 refs.

  11. Simulation of laboratory tests of steel arch support

    Czech Academy of Sciences Publication Activity Database

    Horyl, P.; Šňupárek, Richard; Maršálek, P.; Pacześniowski, P.

    2017-01-01

    Roč. 62, č. 1 (2017), s. 163-176 ISSN 0860-7001 R&D Projects: GA MŠk ED1.1.00/02.0070; GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : total load- bearing capacity * steel arch yielding support * rigid support * FEM Subject RIV: DH - Mining, incl. Coal Mining OBOR OECD: Mining and mineral processing Impact factor: 0.550, year: 2016 http://archiwum.img-pan.krakow.pl/index.php/AMS/article/view/952

  12. Developpement D'un Modele Climatique Regional: Fizr Simulation des Conditions de Janvier de la Cote Ouest Nord Americaine

    Science.gov (United States)

    Goyette, Stephane

    1995-11-01

    Le sujet de cette these concerne la modelisation numerique du climat regional. L'objectif principal de l'exercice est de developper un modele climatique regional ayant les capacites de simuler des phenomenes de meso-echelle spatiale. Notre domaine d'etude se situe sur la Cote Ouest nord americaine. Ce dernier a retenu notre attention a cause de la complexite du relief et de son controle sur le climat. Les raisons qui motivent cette etude sont multiples: d'une part, nous ne pouvons pas augmenter, en pratique, la faible resolution spatiale des modeles de la circulation generale de l'atmosphere (MCG) sans augmenter a outrance les couts d'integration et, d'autre part, la gestion de l'environnement exige de plus en plus de donnees climatiques regionales determinees avec une meilleure resolution spatiale. Jusqu'alors, les MCG constituaient les modeles les plus estimes pour leurs aptitudes a simuler le climat ainsi que les changements climatiques mondiaux. Toutefois, les phenomenes climatiques de fine echelle echappent encore aux MCG a cause de leur faible resolution spatiale. De plus, les repercussions socio-economiques des modifications possibles des climats sont etroitement liees a des phenomenes imperceptibles par les MCG actuels. Afin de circonvenir certains problemes inherents a la resolution, une approche pratique vise a prendre un domaine spatial limite d'un MCG et a y imbriquer un autre modele numerique possedant, lui, un maillage de haute resolution spatiale. Ce processus d'imbrication implique alors une nouvelle simulation numerique. Cette "retro-simulation" est guidee dans le domaine restreint a partir de pieces d'informations fournies par le MCG et forcee par des mecanismes pris en charge uniquement par le modele imbrique. Ainsi, afin de raffiner la precision spatiale des previsions climatiques de grande echelle, nous developpons ici un modele numerique appele FIZR, permettant d'obtenir de l'information climatique regionale valide a la fine echelle spatiale

  13. Simulation and experimental validation of the performance of a absorption refrigerator; Simulation und experimentelle Validierung des Betriebsverhaltens einer Absorptionskaeltemaschine

    Energy Technology Data Exchange (ETDEWEB)

    Olbricht, Michael; Luke, Andrea [Kassel Univ. (Germany). Fachgebiet Technische Thermodynamik

    2015-07-01

    The two biggest obstacles to a stronger market penetration of absorption refrigerators are their high cost and the size of the apparatus, which are due to the inaccurate methods for plant design. In order to contribute to an improved design a thermodynamic model is presented to describe the performance of a absorption refrigerator with the working fluid water/lithium. In this model, the processes are displayed in the single apparatus and coupled to each other in the systemic context. Thereby the interactions between the apparatus can specifically investigated and thus the process limiting component can be identified under the respective conditions. A validation of the simulation model and the boundary conditions used is done based on experimental data operating a self-developed absorption refrigerator. In the simulation, the heat transfer surfaces in accordance with the real system can be specified. The heat transport is taken into account based on typical values for the heat transfer in the individual apparatuses. Simulation results show good agreement with the experimental data. The physical relationships and influences externally defined operating parameters are correctly reproduced. Due to the chosen low heat transfer coefficient, the calculated cooling capacities by the model are below the experimentally measured. Finally, the possibilities and limitations are discussed by using the model and further improvement possibilities are suggested. [German] Die beiden groessten Hemmnisse fuer eine staerkere Marktdurchdringung von Absorptionskaeltemaschinen (AKM) sind deren hohe Anschaffungskosten sowie die Baugroesse der Apparate, die durch die ungenauen Methoden zur Anlagenauslegung begruendet sind. Als Beitrag fuer eine verbesserte Auslegung wird ein thermodynamisches Modell zur Beschreibung des Betriebsverhaltens einer AKM mit dem Arbeitsstoffpaar Wasser/Lithiumbromid vorgestellt. In diesem werden die Prozesse in den Einzelapparaten abgebildet und im systemischen

  14. Numerical simulation of hydrogen-assisted crack initiation in austenitic-ferritic duplex steels

    International Nuclear Information System (INIS)

    Mente, Tobias

    2015-01-01

    Duplex stainless steels have been used for a long time in the offshore industry, since they have higher strength than conventional austenitic stainless steels and they exhibit a better ductility as well as an improved corrosion resistance in harsh environments compared to ferritic stainless steels. However, despite these good properties the literature shows some failure cases of duplex stainless steels in which hydrogen plays a crucial role for the cause of the damage. Numerical simulations can give a significant contribution in clarifying the damage mechanisms. Because they help to interpret experimental results as well as help to transfer results from laboratory tests to component tests and vice versa. So far, most numerical simulations of hydrogen-assisted material damage in duplex stainless steels were performed at the macroscopic scale. However, duplex stainless steels consist of approximately equal portions of austenite and δ-ferrite. Both phases have different mechanical properties as well as hydrogen transport properties. Thus, the sensitivity for hydrogen-assisted damage is different in both phases, too. Therefore, the objective of this research was to develop a numerical model of a duplex stainless steel microstructure enabling simulation of hydrogen transport, mechanical stresses and strains as well as crack initiation and propagation in both phases. Additionally, modern X-ray diffraction experiments were used in order to evaluate the influence of hydrogen on the phase specific mechanical properties. For the numerical simulation of the hydrogen transport it was shown, that hydrogen diffusion strongly depends on the alignment of austenite and δ-ferrite in the duplex stainless steel microstructure. Also, it was proven that the hydrogen transport is mainly realized by the ferritic phase and hydrogen is trapped in the austenitic phase. The numerical analysis of phase specific mechanical stresses and strains revealed that if the duplex stainless steel is

  15. Mapping and simulating systematics due to spatially varying observing conditions in DES science verification data

    International Nuclear Information System (INIS)

    Leistedt, B.; Peiris, H. V.; Elsner, F.; Benoit-Lévy, A.; Amara, A.

    2016-01-01

    Spatially varying depth and the characteristics of observing conditions, such as seeing, airmass, or sky background, are major sources of systematic uncertainties in modern galaxy survey analyses, particularly in deep multi-epoch surveys. We present a framework to extract and project these sources of systematics onto the sky, and apply it to the Dark Energy Survey (DES) to map the observing conditions of the Science Verification (SV) data. The resulting distributions and maps of sources of systematics are used in several analyses of DES–SV to perform detailed null tests with the data, and also to incorporate systematics in survey simulations. We illustrate the complementary nature of these two approaches by comparing the SV data with BCC-UFig, a synthetic sky catalog generated by forward-modeling of the DES–SV images. We analyze the BCC-UFig simulation to construct galaxy samples mimicking those used in SV galaxy clustering studies. We show that the spatially varying survey depth imprinted in the observed galaxy densities and the redshift distributions of the SV data are successfully reproduced by the simulation and are well-captured by the maps of observing conditions. The combined use of the maps, the SV data, and the BCC-UFig simulation allows us to quantify the impact of spatial systematics on N(z), the redshift distributions inferred using photometric redshifts. We conclude that spatial systematics in the SV data are mainly due to seeing fluctuations and are under control in current clustering and weak-lensing analyses. However, they will need to be carefully characterized in upcoming phases of DES in order to avoid biasing the inferred cosmological results. Finally, the framework presented here is relevant to all multi-epoch surveys and will be essential for exploiting future surveys such as the Large Synoptic Survey Telescope, which will require detailed null tests and realistic end-to-end image simulations to correctly interpret the deep, high

  16. Comportement des poteaux composites en profils creux en acier remplis de béton Behavior of composite columns in hollow steel section filled with concrete

    Directory of Open Access Journals (Sweden)

    Othmani N.

    2012-09-01

    Full Text Available Le but de cet article, est la determination des rigidites flexionnelles EIx et EIy d’fune section mixte acier beton et plus precisement d’fun poteau en tube d’facier de section rectangulaire, remplie de beton, sollicitee a la flexion bi-axiale (N, Mx et My. L’festimation des rigidites sera faite a partir d’fune approche theorique par une analyse du poteau en elements finis (element barre a 4 degres de liberte, basee sur les conditions d’fequilibres a mi-portee en utilisant la relation moment-courbure (M–Φ de l’felement deforme par application de l’fequation suivante: EI=M/Φ. Le comportement des materiaux est celui comme adopte par les reglements Eurocode 2 et 3, respectivement pour le beton et l’facier. Afin de valider l’fapproche theorique utilisee dans cette etude, deux comparaisons ont ete faites : une premiere permettant de comparer les resultats des rigidites determinees par les relations moments courbures et celles calculees par l’fEurocode 4 et une deuxieme comparaison entre les charges de ruines de deux poteaux de grandeurs natures avec ceux testes au laboratoire [2]. Au vu des resultats obtenus, nous pouvons conclure que l’approche théorique utilisée dans cette étude ainsi que les modèles de comportement des matériaux sont adéquats pour ce genre de problèmes. The purpose of this paper is the determination of flexural stiffness EIx and EIy of a concrete filled rectangular cross section of a composite steel column, under biaxial bending (N, Mx and My. The rigidities will be estimated from a theoretical approach using a finite element analysis (element bar with 4 degrees of freedom, based on the equilibrium conditions at mid-span using the moment-curvature relationships (M–Φ of the deformed element by applying the following equation: EI=M/Φ. The material behavior is the one adopted by Eurocode 2 and 3, respectively, for concrete and steel. To validate the theoretical approach used, two comparisons

  17. Multiscale simulation of yield strength in reduced-activation ferritic/martensitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chen Chong; Zhang, Chi; Yang, Zhigang [Key Laboratory of Advanced Materials of Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing (China); Zhao, Ji Jun [State Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams, School of Physics and Optoelectronic Technology and College of Advanced Science and Technology, Dalian University of Technology, Dalian (China)

    2017-04-15

    One of the important requirements for the application of reduced-activation ferritic/martensitic (RAFM) steel is to retain proper mechanical properties under irradiation and high-temperature conditions. To simulate the yield strength and stress-strain curve of steels during high-temperature and irradiation conditions, a multiscale simulation method consisting of both microstructure and strengthening simulations was established. The simulation results of microstructure parameters were added to a superposition strengthening model, which consisted of constitutive models of different strengthening methods. Based on the simulation results, the strength contribution for different strengthening methods at both room temperature and high-temperature conditions was analyzed. The simulation results of the yield strength in irradiation and high-temperature conditions were mainly consistent with the experimental results. The optimal application field of this multiscale model was 9Cr series (7–9 wt.%Cr) RAFM steels in a condition characterized by 0.1–5 dpa (or 0 dpa) and a temperature range of 25–500°C.

  18. Simulation of the influence of tar formation in wood gasification processes on the cost of the purified process gas; Simulation des Einflusses der Teerbildung bei der Vergasung von Holz auf die Kosten des gereinigten Produktgases

    Energy Technology Data Exchange (ETDEWEB)

    Saller, G; Krumm, W [Siegen Univ. (Gesamthochschule) (Germany). Inst. fuer Energietechnik

    1998-09-01

    The influence of the gasification process and the related tar formation rate on the cost of gas production is investigated with the aid of process models. The processes of gasification, gas purification and adsorptive treatment of waste water were modelled mathematically with a view to process mechanisms and cost. Simulations of the overall process helped to obtain a quantitative assessment of the cost of product gas as a function of process parameters like gasification process and tar formation. (orig./SR) [Deutsch] Mit Hilfe von Prozessmodellen wird untersucht, welchen Einfluss das Vergasungsverfahren und die damit verbundene Teerbildung mit entsprechenden Reinigungsverfahren auf die Produktionskosten des gereinigten Produktgases besitzt. Hierfuer werden die Prozesse der Vergasung, Gasreinigung und adsorptiven Abwasseraufbereitung hinsichtlich verfahrenstechnischer Zusammenhaenge und Kosten mathematisch modelliert. Durch Simulation des Gesamtprozesses werden quantitativ die Kosten des Produktgases in Abhaengigkeit von Prozessparametern wie Vergasungsverfahren und Teerbildung ermittelt. (orig./SR)

  19. Simulation of the Growth of Austenite from As-Quenched Martensite in Medium Mn Steels

    Science.gov (United States)

    Huyan, Fei; Yan, Jia-Yi; Höglund, Lars; Ågren, John; Borgenstam, Annika

    2018-04-01

    As part of an ongoing development of third-generation advanced high-strength steels with acceptable cost, austenite reversion treatment of medium Mn steels becomes attractive because it can give rise to a microstructure of fine mixture of ferrite and austenite, leading to both high strength and large elongation. The growth of austenite during intercritical annealing is crucial for the final properties, primarily because it determines the fraction, composition, and phase stability of austenite. In the present work, the growth of austenite from as-quenched lath martensite in medium Mn steels has been simulated using the DICTRA software package. Cementite is added into the simulations based on experimental observations. Two types of systems (cells) are used, representing, respectively, (1) austenite and cementite forming apart from each other, and (2) austenite forming on the cementite/martensite interface. An interfacial dissipation energy has also been added to take into account a finite interface mobility. The simulations using the first type of setup with an addition of interfacial dissipation energy are able to reproduce the observed austenite growth in medium Mn steels reasonably well.

  20. Microstructure and embrittlement of VVER 440 reactor pressure vessel steels; Microstructure et fragilisation des aciers de cuve des reacteurs nucleaires VVER 440

    Energy Technology Data Exchange (ETDEWEB)

    Hennion, A

    1999-03-15

    27 VVER 440 pressurised water reactors operate in former Soviet Union and in Eastern Europe. The pressure vessel, is made of Cr-Mo-V steel. It contains a circumferential arc weld in front of the nuclear core. This weld undergoes a high neutron flux and contains large amounts of copper and phosphorus, elements well known for their embrittlement potency under irradiation. The embrittlement kinetic of the steel is accelerated, reducing the lifetime of the reactor. In order to get informations on the microstructure and mechanical properties of these steels, base metals, HAZ, and weld metals have been characterized. The high amount of phosphorus in weld metals promotes the reverse temper embrittlement that occurs during post-weld heat treatment. The radiation damage structure has been identified by small angle neutron scattering, atomic probe, and transmission electron microscopy. Nanometer-sized clusters of solute atoms, rich in copper with almost the same characteristics as in western pressure vessels steels, and an evolution of the size distribution of vanadium carbides, which are present on dislocation structure, are observed. These defects disappear during post-irradiation tempering. As in western steels, the embrittlement is due to both hardening and reduction of interphase cohesion. The radiation damage specificity of VVER steels arises from their high amount of phosphorus and from their significant density of fine vanadium carbides. (author)

  1. Effect of soil compositions on the electrochemical corrosion behavior of carbon steel in simulated soil solution

    Energy Technology Data Exchange (ETDEWEB)

    Liu, T.M. [College of Materials Science and Engineering, Chongqing University (China); Luo, S.X. [Department of Chemistry, Zunyi Normal College, Zunyi (China); Sun, C. [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang (China); Wu, Y.H.

    2010-04-15

    In this study, effect of cations, Ca{sup 2+}, Mg{sup 2+}, K{sup +}, and anions, SO{sub 4}{sup 2-}, HCO{sub 3}{sup -}, NO{sub 3}{sup -} on electrochemical corrosion behavior of carbon steel in simulated soil solution was investigated through potentiodynamic polarization curves and electrochemical impedance spectroscopy. The results indicate that the Ca{sup 2+}and Mg{sup 2+} can decrease the corrosion current density of carbon steel in simulated soil solution, and K{sup +}, SO{sub 4}{sup 2-}, HCO{sub 3}{sup -}, and NO{sub 3}{sup -} can increase the corrosion density. All the above ions in the simulated soil solution can decrease its resistivity, but they have different effect on the charge transfer resistivity. This finding can be useful in evaluating the corrosivity of certain soil through chemical analysis, and provide data for construction engineers. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  2. Steel billet reheat simulation with growth of oxide layer and investigation on zone temperature sensitivity

    International Nuclear Information System (INIS)

    Dubey, Satish Kumar; Srinivasan, P.

    2014-01-01

    This paper presents a three-dimensional heat conduction numerical model and simulation of steel billet reheating in a reheat furnace. The model considers the growth of oxide scale on the billet surfaces. Control-volume approach and implicit scheme of finite difference method are used to discretize the transient heat conduction equation. The model is validated with analytical results subject to limited conditions. Simulations are carried out for predictions of three-dimensional temperature filed in the billet and oxide scale growth on the billet surfaces. The model predictions are in agreement with expected trends. It was found that the effect of oxide scale on billet heating is considerable. In order to investigate the effect of zone temperatures on the responses, a parametric sensitivity subject to six responses of interest are carried out using analysis of mean approach. The simulation approach and parametric study presented will be useful and applicable to the steel industry.

  3. Electrochemical impedance spectrometry using 316L steel, hastelloy, maraging, Inconel 600, Elgiloy, carbon steel, TiN and NiCr. Simulation in tritiated water. 2 volumes

    International Nuclear Information System (INIS)

    Bellanger, G.

    1994-03-01

    Polarization and electrochemical impedance spectrometry curves are presented and discussed. These curves make it possible to ascertain the corrosion domains and to compare the slow and fast kinetics (voltammetry) of different stainless steel alloys. These corrosion kinetics, the actual or simulated tritiated water redox potentials, and the corrosion potentials provide a classification of the steels studied here: 316L, Hastelloy, Maraging, Inconel 600, Elgiloy, carbon steel and TiN and NiCr deposits. From the results it can be concluded that Hastelloy and Elgiloy have the best corrosion resistance. (author). 49 refs., 695 figs., tabs

  4. Passivation of duplex stainless steel in solutions simulating chloride-contaminated concrete

    Directory of Open Access Journals (Sweden)

    Takenouti, H.

    2007-12-01

    Full Text Available Most studies published to date on the corrosion behaviour of stainless reinforcing steel are based on austenitic steel. The market presence of corrugated duplex steel is growing, however. The present study compared passivity in 2205 type duplex and 304 type austenitic stainless steel. Polarization tests in chloride-containing Ca(OH2 solutions confirmed the exceptional performance of duplex steels. X-ray photoelectronic spectroscopy (XPS showed that the passive layer generated on duplex stainless steel in media simulating concrete pore solutions had a higher Cr content than the layer formed on steel in contact with the air. The XPS results also revealed that in duplex steel the form adopted by the passive layer Fe oxides was Fe3O4 in the solutions simulating concrete, rather than Fe2O3, as in duplex steel exposed to air. Electrochemical impedance spectroscopy (EIS can be used to monitor the transformations taking place in the passive layer and analyze the factors involved.La mayoría de los estudios publicados hasta el momento sobre el comportamiento frente a la corrosión de armaduras de acero inoxidable se basan en aceros austeníticos. Sin embargo, la presencia en el mercado de aceros corrugados dúplex es cada vez más importante. En este trabajo se analiza la pasividad de un acero inoxidable dúplex tipo 2205 en comparación con la de un inoxidable austenítico tipo 304. Los ensayos de polarización en disoluciones de Ca(OH2 con cloruros confirman el excepcional comportamiento de los aceros dúplex. La espectroscopía fotoelectrónica de rayos X (XPS informa de que la capa pasiva generada en aceros inoxidables dúplex en medios que simulan la disolución de los poros del hormigón posee mayor contenido en óxidos de Cr que la formada en aire. También se puede deducir de los resultados de XPS que los óxidos de Fe de la capa pasiva de los aceros dúplex se encuentran en forma de Fe3O4 en las disoluciones que simulan el hormigón en vez de en

  5. Electrochemical behaviour of iron and AISI 304 stainless steel in simulated acid rain solution

    Energy Technology Data Exchange (ETDEWEB)

    Pilic, Zora; Martinovic, Ivana [Mostar Univ. (Bosnia and Herzegovina). Dept. of Chemistry

    2016-10-15

    The growth mechanism and properties of the oxide films on iron and AISI 304 stainless steel were studied in simulated acid rain (pH 4.5) by means of electrochemical techniques and atomic absorption spectrometry. The layer-pore resistance model was applied to explain a potentiodynamic formation of surface oxides. It was found that the growth of the oxide film on iron takes place by the low-field migration mechanism, while that on the stainless steel takes place by the high-field mechanism. Kinetic parameters were determined. Impedance measurements revealed that Fe surface film has no protective properties at the open circuit potential, while the resistance of stainless steel oxide film is very high. The concentration of the metallic ions released into solution and measured by atomic absorption spectroscopy was in accordance with the results obtained from the electrochemical techniques.

  6. Fractured Reservoir Simulation: a Challenging and Rewarding Issue Simulation des réservoirs fracturés : un défi et un enjeu

    Directory of Open Access Journals (Sweden)

    Bourbiaux B.

    2010-03-01

    Full Text Available The recent years have seen a growing awareness of the role played by fractures in petroleum reservoirs production and recovery. Hence, much effort was devoted to the diagnosis of fracture presence and impact on production. However, turning that diagnosis into field development decisions goes through reservoir simulation. This paper addresses some of the specificities of fractured reservoirs that make that their simulation is both challenging and rewarding. Indeed, the integration of fractures into a flow simulation model is not straightforward because of the existing gap between the geological fault/fracture network and the fingerprint of that network on often-complex recovery mechanisms. Considering that fractures may impede or enhance production, fractured reservoir simulation may be seen as a technical challenge with potentially-high reward. This paper underlines that specific framework as an introduction to two technical articles dedicated to dual-porosity reservoir simulation. Although it constitutes another major aspect of any fractured reservoir study, the geological characterization of fractures is not discussed herein, but only evoked because of more and more integration of static and dynamic aspects. Au cours des années récentes, la prise de conscience du rôle des fractures sur la production et la récupération des champs est devenue de plus en plus forte au sein de la communauté pétrolière. Aussi beaucoup d’efforts ont-ils été consacrés à la détection des fractures et à l’analyse de leur impact sur la production. Toutefois, la prise en considération de ces observations dans les choix de développement des champs passe par la simulation de réservoir. Cet article traite des spécificités propres aux réservoirs fracturés et qui font de leur simulation à la fois un défi et un enjeu. En effet, l’intégration des fractures dans un modèle de simulation des écoulements n’est pas immédiate en raison du difficile

  7. Thermodynamic modeling and kinetics simulation of precipitate phases in AISI 316 stainless steels

    International Nuclear Information System (INIS)

    Yang, Y.; Busby, J.T.

    2014-01-01

    This work aims at utilizing modern computational microstructural modeling tools to accelerate the understanding of phase stability in austenitic steels under extended thermal aging. Using the CALPHAD approach, a thermodynamic database OCTANT (ORNL Computational Thermodynamics for Applied Nuclear Technology), including elements of Fe, C, Cr, Ni, Mn, Mo, Si, and Ti, has been developed with a focus on reliable thermodynamic modeling of precipitate phases in AISI 316 austenitic stainless steels. The thermodynamic database was validated by comparing the calculated results with experimental data from commercial 316 austenitic steels. The developed computational thermodynamics was then coupled with precipitation kinetics simulation to understand the temporal evolution of precipitates in austenitic steels under long-term thermal aging (up to 600,000 h) at a temperature regime from 300 to 900 °C. This study discusses the effect of dislocation density and difusion coefficients on the precipitation kinetics at low temperatures, which shed a light on investigating the phase stability and transformation in austenitic steels used in light water reactors

  8. Finite element simulation of photoacoustic fiber optic sensors for surface corrosion detection on a steel rod

    Science.gov (United States)

    Tang, Qixiang; Owusu Twumasi, Jones; Hu, Jie; Wang, Xingwei; Yu, Tzuyang

    2018-03-01

    Structural steel members have become integral components in the construction of civil engineering infrastructures such as bridges, stadiums, and shopping centers due to versatility of steel. Owing to the uniqueness in the design and construction of steel structures, rigorous non-destructive evaluation techniques are needed during construction and operation processes to prevent the loss of human lives and properties. This research aims at investigating the application of photoacoustic fiber optic transducers (FOT) for detecting surface rust of a steel rod. Surface ultrasonic waves propagation in intact and corroded steel rods was simulated using finite element method (FEM). Radial displacements were collected and short-time Fourier transform (STFT) was applied to obtain the spectrogram. It was found that the presence of surface rust between the FOT and the receiver can be detected in both time and frequency domain. In addition, spectrogram can be used to locate and quantify surface rust. Furthermore, a surface rust detection algorithm utilizing the FOT has been proposed for detection, location and quantification of the surface rust.

  9. Modeling Fragment Simulating Projectile Penetration into Steel Plates Using Finite Elements and Meshfree Particles

    Directory of Open Access Journals (Sweden)

    James O’Daniel

    2011-01-01

    Full Text Available Simulating fragment penetration into steel involves complicated modeling of severe behavior of the materials through multiple phases of response. Penetration of a fragment-like projectile was simulated using finite element (FE and meshfree particle formulations. Extreme deformation and failure of the material during the penetration event were modeled with several approaches to evaluate each as to how well it represents the actual physics of the material and structural response. A steel Fragment Simulating Projectile (FSP – designed to simulate a fragment of metal from a weapon casing – was simulated for normal impact into a flat square plate. A range of impact velocities was used to examine levels of exit velocity ranging from relatively small to one on the same level as the impact velocity. The numerical code EPIC, used for all the simulations presented herein, contains the element and particle formulations, as well as the explicit methodology and constitutive models needed to perform these simulations. These simulations were compared against experimental data, evaluating the damage caused to the projectile and the target plates, as well as comparing the residual velocity when the projectile perforated the target.

  10. Contribution to the study of influences in emission spectrography on solutions. Application to a general analysis method for stainless steels (1961); Contribution a l'etude des influences en spectographie d'emission sur solution. Application a une methode generale d'analyse des aciers inoxydables (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Baudin, G [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1961-11-15

    In order to establish a general method of analysis of stainless steels, by means of spark spectroscopy on solutions, a systematic study has been made of the factors involved. The variations in acidity of the solutions, or in the ratio of concentrations of two acids at constant pH, lead to a displacement of the calibration curve. Simple relations have been established between the concentration of the extraneous elements, and the effects produced, for the constituents Fe, Ti, Ni, Cr, Mn; a general method using abacus is proposed for steels containing only these elements. The interactions in the case of the elements Mo, Nb, Ta, W, were more complex, so that the simultaneous separation was studied with the help of ion-exchange resins. A general method of analysis is proposed for stainless steels. (author) [French] En vue d'etablir une methode generale d'analyse des aciers inoxydables par spectrographie d'etincelles sur solution, on a effectue une etude systematique des influences. Les variations de l'acidite des solutions ou du rapport des concentrations de deux acides a pH constant, entrainent un deplacement des courbes d'etalonnage. On a etabli des relations simples entre la teneur des tiers elements et les effets produits pour les constituants Fe, Ti, Ni, Cr, Mn; une methode generale avec abaques est proposee pour les aciers contenant ces seuls elements. Les influences dans le cas des elements Mo, Nb, Ta, W etant plus complexes, on eut a etudier la separation simultanee a l'aide de resines echangeuses d'ions. On propose une methode generale d'analyse des aciers inoxydables. (auteur)

  11. Fuel-steel mixing and radial mesh effects in power excursion simulations

    International Nuclear Information System (INIS)

    Chen, X.-N.; Rineiski, A.; Gabrielli, F.; Andriolo, L.; Vezzoni, B.; Li, R.; Maschek, W.; Kiefhaber, E.

    2016-01-01

    Highlights: • Fuel-steel mixing and radial mesh effects are significant on power excursion. • The earliest power peak is reduced and retarded by these two effects. • Unprotected loss of coolant transients in ESFR core are calculated. - Abstract: This paper deals with SIMMER-III once-through simulations of the earliest power excursion initiated by an unprotected loss of flow (ULOF) in the Working Horse design of the European Sodium Cooled Fast Reactor (ESFR). Since the sodium void effect is strictly positive in this core and dominant in the transient, a power excursion is initiated by sodium boiling in the ULOF case. Two major effects, namely (1) reactivity effects due to fuel-steel mixing after melting and (2) the radial mesh size, which were not considered originally in SIMMER simulations for ESFR, are studied. The first effect concerns the reactivity difference between the heterogeneous fuel/clad/wrapper configuration and the homogeneous mixture of steel and fuel. The full core homogenization (due to melting) effect is −2 $, though a smaller effect takes place in case of partial core melting. The second effect is due to the SIMMER sub-assembly (SA) coarse mesh treatment, where a simultaneous sodium boiling onset in all SAs belonging to one ring leads to an overestimated reactivity ramp. For investigating the influence of fuel/steel mixing effects, a lumped “homogenization” reactivity feedback has been introduced, being proportional to the molten steel mass. For improving the coarse mesh treatment, we employ finer radial meshes to take the subchannel effects into account, where the side and interior channels have different coolant velocities and temperatures. The simulation results show that these two effects have significant impacts on the earliest power excursion after the sodium boiling.

  12. The efficiency of a corrosion inhibitor on steel in a simulated concrete environment

    Energy Technology Data Exchange (ETDEWEB)

    Gartner, Nina; Kosec, Tadeja, E-mail: tadeja.kosec@zag.si; Legat, Andraž

    2016-12-01

    The aim of the present work was to characterize the efficiency of a corrosion inhibitor on steel in a simulated concrete pore solution. Laboratory measurements were performed at various chloride and inhibitor concentrations in order to simulate different applications of the inhibitor when used for the protection or rehabilitation of steel reinforcement in concrete. Two electrochemical techniques, i.e. potentiodynamic polarization scans and electrochemical impedance spectroscopy, were used for this study. The exposed surfaces of the steel specimens were subsequently investigated by Raman spectroscopy and scanning electron microscopy. It was found that the inhibitor can efficiently retard the corrosion of steel in a simulated concrete pore solution at concentrations of the inhibitor >2.0% and of chlorides <0.3% at a pH 10.5. On the other hand, when these conditions are not fulfilled, localized corrosion was observed. The results of the Raman and SEM/EDS analysis showed various morphologies of corrosion products and different types of corrosion attack depending on the pH of the pore solution, and the applied concentrations of the chlorides and the inhibitor. - Highlights: • Electrochemical studies performed at various Cl{sup −} and inhibitor concentrations. • Exposed steel surfaces investigated by Raman spectroscopy and SEM. • Cl{sup −}/inhibitor ratio is important parameter for the inhibitor's efficiency. • The corrosion can re-occur if the concentration of the inhibitor is reduced. • Different corrosion behaviour and oxides in the presence of inhibitor and/or Cl{sup −}.

  13. Simulation of radiation induced segregation and PWSCC susceptibility for austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto Koji; Yonezawa, Toshio; Iwamura, Toshihiko [Mitsubishi Heavy Industries Ltd., Takasago, Hyogo (Japan). Takasago R and D Center; Ajiki, Kazuhide [Mitsubishi Heavy Industries Ltd., Kobe (Japan). Kobe Shipyard and Machinery Works; Urata, Sigeru [General Office of Nuclear and Fossil Power Production, Kansai Electric Power Co., Inc., Osaka (Japan)

    2000-08-01

    Recently, irradiation assisted stress corrosion cracking (IASCC) of austenitic stainless steels for core internal components materials become a subject of discussion in light water reactors (LWRs). IASCC has not been found in Pressurized Water Reactors (PWRs). However, the authors have investigated on the possibility of IASCC of austenitic stainless steels for core internal materials so as to be able to estimate the degradation of PWR plants up to the end of their lifetime. In this study, in order to verify the hypothetical that the IASCC in PWRs shall be caused by the primary water stress corrosion cracking (PWSCC) as a result of radiation induced segregation (RIS) at grain boundaries, the authors simulated RIS at grain boundaries of austenitic stainless steels based on previous study and estimated RIS tendency after long time operation. And the authors melted the test alloys whose bulk compositions simulated the grain boundary compositions of irradiated austenitic stainless steels and made clear chromium-nickel-silicon compositions for PWSCC susceptibility area in austenitic alloys by slow strain rate tensile (SSRT) test. (author)

  14. Simulation of radiation induced segregation and PWSCC susceptibility for austenitic stainless steels

    International Nuclear Information System (INIS)

    Fujimoto Koji; Yonezawa, Toshio; Iwamura, Toshihiko

    2000-01-01

    Recently, irradiation assisted stress corrosion cracking (IASCC) of austenitic stainless steels for core internal components materials become a subject of discussion in light water reactors (LWRs). IASCC has not been found in Pressurized Water Reactors (PWRs). However, the authors have investigated on the possibility of IASCC of austenitic stainless steels for core internal materials so as to be able to estimate the degradation of PWR plants up to the end of their lifetime. In this study, in order to verify the hypothetical that the IASCC in PWRs shall be caused by the primary water stress corrosion cracking (PWSCC) as a result of radiation induced segregation (RIS) at grain boundaries, the authors simulated RIS at grain boundaries of austenitic stainless steels based on previous study and estimated RIS tendency after long time operation. And the authors melted the test alloys whose bulk compositions simulated the grain boundary compositions of irradiated austenitic stainless steels and made clear chromium-nickel-silicon compositions for PWSCC susceptibility area in austenitic alloys by slow strain rate tensile (SSRT) test. (author)

  15. Simulation of transient fluid flow in mold region during steel continuous casting

    International Nuclear Information System (INIS)

    Liu, R; Thomas, B G; Sengupta, J

    2012-01-01

    A system of models has been developed to study transient flow during continuous casting and applied to simulate an event of multiple stopper-rod movements. It includes four sub-models to incorporate different aspects in this transient event. A three-dimensional (3-D) porous-flow model of the nozzle wall calculates the rate argon gas flow into the liquid steel, and the initial mean bubble size is estimated. Transient CFD models simulate multiphase flow of steel and gas bubbles in the Submerged Entry Nozzle (SEN) and mold and have been validated with experimental data from both nail dipping and Sub-meniscus Velocity Control (SVC) measurements. To obtain the transient inlet boundary conditions for the simulation, two semi-empirical models, a stopper-rod-position based model and a metal-level-based model, predict the liquid steel flow rate through the SEN based on recorded plant data. Finally the model system was applied to study the effects of stopper rod movements on SEN/mold flow patterns. Meniscus level fluctuations were calculated using a simple pressure method and compared well with plant measurements. Insights were gained from the simulation results to explain the cause of meniscus level fluctuations and the formation of sliver defects during stopper rod movements.

  16. Simulation of press-forming for automobile part using ultra high tension steel

    Directory of Open Access Journals (Sweden)

    Tanabe I.

    2012-08-01

    Full Text Available In recent years, ultra high tension steel has gradually been used in the automobile industry. The development of press-forming technology is now essential by reason of its high productivity and high product quality. In this study, tensile tests were performed with a view to understanding the material properties. Press-forming tests were then carried out with regard to the behaviors of spring back and deep-drawability, and manufacturing a real product. The ultra high tension steel used in the experiments had a thickness of 1 mm and a tensile strength of 1000 MPa. Finally, simulations of spring back, deep-drawability and manufacturing a real product in ultra high tension steel were conducted and evaluated in order to calculate the optimum-press-forming conditions and the optimum shape of the die. FEM with non-linear and dynamic analysis using Euler-Lagrange’s element was used for the simulations. It is concluded from the results that (1 the simulations conformed to the results of the experiments (2 the simulations proved very effective for calculating the optimum press conditions and die shape.

  17. Steel-concrete bond model for the simulation of reinforced concrete structures

    International Nuclear Information System (INIS)

    Mang, Chetra

    2015-01-01

    Reinforced concrete structure behavior can be extremely complex in the case of exceeding the cracking threshold. The composite characteristics of reinforced concrete structure should be finely presented especially in the distribution stress zone between steel-concrete at their interface. In order to compute the industrial structures, a perfect relation hypothesis between steel and concrete is supposed in which the complex phenomenon of the two-material relation is not taken into account. On the other hand, this perfect relation is unable to predict the significant disorders, the repartition, and the distribution of the cracks, which is directly linked to the steel. In literature, several numerical methods are proposed in order to finely study the concrete-steel bond behavior, but these methods give many difficulties in computing complex structures in 3D. With the results obtained in the thesis framework of Torre-Casanova (2012), the new concrete-steel bond model has been developed to improve performances (iteration numbers and computational time) and the representation (cyclic behavior) of the initial one. The new model has been verified with analytical solution of steel-concrete tie and validated with the experimental results. The new model is equally tested with the structural scale to compute the shear wall behavior in the French national project (CEOS.fr) under monotonic load. Because of the numerical difficulty in post-processing the crack opening in the complex crack formation, a new crack opening method is also developed. This method consists of using the discontinuity of relative displacement to detect the crack position or using the slip sign change between concrete-steel. The simulation-experiment comparison gives validation of not only the new concrete-steel bond model but also the new crack post-processing method. Finally, the cyclic behavior of the bond law with the non-reduced envelope is adopted and integrated in the new bond model in order to take

  18. Simulation and experimental approach to CVD-FBR aluminide coatings on ferritic steels under steam oxidation

    International Nuclear Information System (INIS)

    Leal, J.; Alcala, G.; Bolivar, F.J.; Sanchez, L.; Hierro, M.P.; Perez, F.J.

    2008-01-01

    The ferritic steels used to produce structural components for steam turbines are susceptible to strong corrosion and creep damage due to the extreme working conditions pushed to increase the process efficiency and to reduce pollutants release. The response of aluminide coatings on the P-92 ferritic steel, deposited by CVD-FBR, during oxidation in a simulated steam environment was studied. The analyses were performed at 650 deg. C in order to simulate the working conditions of a steam turbine, and 800 deg. C in order to produce a critical accelerated oxidation test. The Thermo-Calc software was used to predict the different solid phases that could be generated during the oxidation process, in both, coated and uncoated samples. In order to validate the thermodynamic results, the oxides scales produced during steam tests were characterized by different techniques such as XRD, SEM and EDS. The preliminary results obtained are discussed in the present work

  19. Constant extension rate testing of Type 304L stainless steel in simulated waste tank environments

    International Nuclear Information System (INIS)

    Wiersma, B.J.

    1992-01-01

    New tanks for storage of low level radioactive wastes will be constructed at the Savannah River Site (SRS) of AISI Type 304L stainless steel (304L). The presence of chlorides and fluorides in the wastes may induce Stress Corrosion Cracking (SCC) in 304L. Constant Extension Rate Tests (CERT) were performed to determine the susceptibility of 304L to SCC in simulated wastes. In five of the six tests conducted thus far 304L was not susceptible to SCC in the simulated waste environments. Conflicting results were obtained in the final test and will be resolved by further tests. For comparison purposes the CERT tests were also performed with A537 carbon steel, a material similar to that utilized for the existing nuclear waste storage tanks at SRS

  20. Passivation and electrochemical behavior of 316L stainless steel in chlorinated simulated concrete pore solution

    Science.gov (United States)

    Luo, Hong; Su, Huaizhi; Dong, Chaofang; Li, Xiaogang

    2017-04-01

    In this paper, the passivation and electrochemical behavior of 316L stainless steel in chlorinated simulated concrete pore solutions at different pH was evaluated by potentiodynamic measurements, electrochemical impedance spectroscopy. The composition of the passive film and surface morphology were investigated by X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), and scanning electron microscopy, respectively. The results reveal that metastable pitting susceptibility, stable pitting corrosion, and composition of the passive film are influenced by pH value. After long time immersion, a bilayer structure passive film can be formed in this environment. The appearance of molybdates on the outermost surface layer, further enhancing the stability of the passive film. Moreover, the good pitting corrosion resistance of 316L stainless steel in simulated concrete pore solution without carbonated is mainly due to the presence of high Cr/Fe ratio and molybdates ions within the passive film.

  1. Modeling and simulation of Charpy impact test of maraging steel 300 using Abaqus

    Science.gov (United States)

    Madhusudhan, D.; Chand, Suresh; Ganesh, S.; Saibhargavi, U.

    2018-03-01

    This work emphasizes the modeling and simulation of Charpy impact test to evaluate fracture energy at different pendulum velocities of armor maraging steel 300 using ABAQUS. To evaluate the fracture energy, V-notch specimen is fractured using the Johnson and Cook Damage model. The Charpy impact tests are of great importance related to fracture properties of steels. The objective of this work is to present absorbed energy variation at pendulum velocities of 5 m/sec, 6 m/sec, 7 m/sec and 9 m/sec in addition to stress distribution at v-notch. Finite Element Method of modeling for three dimensional specimens is used for simulation in commercial software of ABAQUS.

  2. White book Escrime. Climatic simulation studies; Livre blanc Escrime. Etude des simulations climatiques

    Energy Technology Data Exchange (ETDEWEB)

    Terray, L [CERFACS, 31 - Toulouse (France); Braconnot, P [Institut Pierre-Simon Laplace IPSL/LSCE, CEA-Orme des Merisiers, 91 - Gif-sur-Yvette (France)

    2007-01-15

    The ESCRIME project aims to manage the analysis realized on the climatic simulations on the framework of the fourth report of the GIEC (group of intergovernmental experts on the climate evolution), in particularly the simulations based on french models. This white book is constituted by 8 chapters: the global scenario, the climatic sensibility, the variation modes, the regionalization and the extremes, the hydrological cycle, the polar regions and the cryo-sphere, the carbon cycle, detection and attributions. (A.L.B.)

  3. Static and Dynamic Disorder in Bacterial Light-Harvesting Complex LH2: A 2DES Simulation Study.

    Science.gov (United States)

    Rancova, Olga; Abramavicius, Darius

    2014-07-10

    Two-dimensional coherent electronic spectroscopy (2DES) is a powerful technique in distinguishing homogeneous and inhomogeneous broadening contributions to the spectral line shapes of molecular transitions induced by environment fluctuations. Using an excitonic model of a double-ring LH2 aggregate, we perform simulations of its 2DES spectra and find that the model of a harmonic environment cannot provide a consistent set of parameters for two temperatures: 77 K and room temperature. This indicates the highly anharmonic nature of protein fluctuations for the pigments of the B850 ring. However, the fluctuations of B800 ring pigments can be assumed as harmonic in this temperature range.

  4. Some types of difficulty encountered during the simulation of heat exchangers (1961); Quelques types de difficultes rencontrees lors de la simulation des echangeurs (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Bettembourg, D [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    After recalling that the simulation of exchangers poses problems which are often difficult to solve, the author points out that these problems appear first of all when the physical phenomena are described in terms of equations. They appear also during the solving of the equations since expressions which are more and more complex can give rise to unstable electronic structures. These difficulties are developed during the analysis of various types of exchangers and in each case the solutions chosen are given. (author) [French] On rappelle que la simulation des echangeurs pose un certain nombre de problemes souvent difficiles a resoudre. Les difficultes apparaissent d'abord lors de la mise en equations des phenomenes physiques; elles apparaissent ensuite au moment de la resolution, car des formulations de plus en plus complexes peuvent donner lieu a des structures electroniques instables. On developpe ces difficultes en faisant l'analyse de quelques types varies d'echangeurs et l'on indique dans chacun des cas les solutions qui ont ete retenues. (auteur)

  5. Experimentation and numerical simulation of steel fibre reinforced concrete pipes

    International Nuclear Information System (INIS)

    Fuente, A. de la; Domingues de Figueiredo, A.; Aguado, A.; Molins, C.; Chama Neto, P. J.

    2011-01-01

    The results concerning on an experimental and a numerical study related to SFRCP are presented. Eighteen pipes with an internal diameter of 600 mm and fibre dosages of 10, 20 and 40 kg/m3 were manufactured and tested. Some technological aspects were concluded. Likewise, a numerical parameterized model was implemented. With this model, the simulation of the resistant behaviour of SFRCP can be performed. In this sense, the results experimentally obtained were contrasted with those suggested by means MAP reaching very satisfactory correlations. Taking it into account, it could be said that the numerical model is a useful tool for the optimal design of the SFRCP fibre dosages, avoiding the need of the systematic employment of the test as an indirect design method. Consequently, the use of this model would reduce the overall cost of the pipes and would give fibres a boost as a solution for this structural typology. (Author) 27 refs.

  6. Predictions of steam generator soiling - experiment, calculation, numerical simulation; Vorhersage des Ansatzverhaltens in Dampferzeugern - Experiment, Berechnung und numerische Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, W.; Hildebrand, V.; Ullrich, B.; Szilagyi, J.

    2000-07-01

    Power plant reliability depends to a large extent on steam generator operation. Investigations were therefore carried out for early detection of combustion chamber soiling at different operating conditions. Apart from CFD numerical simulations of the gaseous phase and particle tracks, both in the original and coupled with thermochemical calculations, emphasis was given to validations with measured values in the original plant, in combustion chamber models, and in experimental facilities. Three different fuels with different composition and behaviour were investigated, i.e. oil shales, mixed coal, and coal pretreated with sorption agents. Apart from the influence of the temperature and reaction conditions (oxygen concentration) in the vicinity of the particle, also different times of residue were investigated. [German] Die Betriebssicherheit von Kraftanlagen wird massgeblich von der Arbeitsweise der Dampferzeuger bestimmt. Ziel dieses Forschungskomplexes ist es, fruehzeitig Aussagen zum Ansatzverhalten im Feuerraum bei verschiedenen Betriebsbedingungen zu treffen. Neben der numerischen Simulation der Gasphase und der Partikelbahnen mit CFD-Codes im Original und der Kopplung mit thermochemischen Berechnungen stehen vor allem Validierungen mit Messwerten am Original, an Feuerraummodellen und Versuchsanlagen im Vordergrund der Arbeiten. Die hier vorgestellten Untersuchungen erfolgten an drei unterschiedlichen Brennstoffen, die sich sowohl in der Zusammensetzung als auch im Einsatz stark voneinander unterscheiden. Dies sind: Oelschiefer, Mischkohle und vorbehandelte Kohle mit Sorbent. Dabei werden neben den Einfluessen der Temperatur und der Reaktionsbedingung (Sauerstoffgehalt) in der Umgebung des Partikels auch verschiedene Verweilzeiten untersucht. (orig./AKF)

  7. Planning of overhead contact lines and simulation of the pantograph running; Oberleitungsplanung und Simulation des Stromabnehmerlaufes

    Energy Technology Data Exchange (ETDEWEB)

    Hofbauer, Gerhard [ALPINE-ENERGIE Oesterreich GmbH, Linz (Austria); Hofbauer, Werner

    2009-07-01

    Using the software FLTG all planning steps for overhead contact lines can be carried out based on the parameters of the contact line type and the line data. Contact line supports and individual spans are presented graphically. The geometric interaction of pantograph and contact line can be simulated taking into account the pantograph type, its sway and the wind action. Thus, the suitability of a line for the interoperability of the transEuropean rail system can be demonstrated. (orig.)

  8. Clim 2000: simulating the heating of premises; Clim 2000: la simulation du chauffage des locaux

    Energy Technology Data Exchange (ETDEWEB)

    Dalicieux, P.; Hubert, J.L.

    1999-07-01

    Electric power is widely used for heating or air conditioning in homes and office buildings. Today, the consumer demands that heating system be comfortable, easy to use and as economical as possible. The optimisation of an existing plant meticulous sharp studies: what quantity of air escapes when a door is open? How does humidity affect energy consumption? Which control system is the most convenient? Numerical simulation is particularly well suited for solving these problems. (authors)

  9. Simulation of Naturally Fractured Reservoirs. State of the Art Simulation des réservoirs naturellement fracturés. État de l’art

    Directory of Open Access Journals (Sweden)

    Lemonnier P.

    2010-04-01

    Full Text Available Naturally fractured reservoirs contain a significant amount of the world oil reserves. The production of this type of reservoirs constitutes a challenge for reservoir engineers. Use of reservoir simulators can help reservoir engineers in the understanding of the main physical mechanisms and in the choice of the best recovery process and its optimization. Significant progress has been made since the first publications on the dual-porosity concept in the sixties. This paper and the preceding one (Part 1 present the current techniques of modeling used in industrial simulators. The optimal way to predict matrix-fracture transfers at the simulator cell scale has no definite answer and various methods are implemented in industrial simulators. This paper focuses on the modeling of physical mechanisms driving flows and interactions/ exchanges within and between fracture and matrix media for a better understanding of proposed flow formula and simulation methods. Typical features of fractured reservoir numerical simulations are also described with an overview of the implementation of geomechanics effects, an application of uncertainty assessment methodology to a fractured gas reservoir and finally a presentation of a history matching methodology for fractured reservoirs. Les réservoirs naturellement fracturés contiennent une partie significative des réserves en huile mondiales. La production de ce type de réservoirs constitue un défi pour les ingénieurs de réservoir. L’utilisation des simulateurs de réservoir peut aider l’ingénieur de réservoir à mieux comprendre les principaux mécanismes physiques, à choisir le procédé de récupération le mieux adapté et à l’optimiser. Des progrès sensibles ont été réalisés depuis les premières publications sur le concept double-milieu dans les années soixante. Cet article et le précédent (Partie 1 présentent les techniques actuelles de modélisation utilisées dans les simulateurs

  10. The hardiness of numerical simulation of TIG welding. Application to stainless steel 316L structures

    International Nuclear Information System (INIS)

    El-Ahmar, Walid; Jullien, Jean-Francois; Gilles, Philippe; Taheri, Said; Boitout, Frederic

    2006-01-01

    The welding numerical simulation is considered as one of the mechanics problems the most un-linear on account of the great number of the parameters required. The analysis of the hardiness of the welding numerical simulation is a current questioning whose expectation is to specify welding numerical simulation procedures allowing to guarantee the reliability of the numerical result. In this work has been quantified the aspect 'uncertainties-sensitivity' imputable to different parameters which occur in the simulation of stainless steel 316L structures welded by the TIG process: that is to say the mechanical and thermophysical parameters, the types of modeling, the adopted behaviour laws, the modeling of the heat contribution.. (O.M.)

  11. Microstructural changes after control rolling and interrupted accelerated cooling simulations in pipeline steel

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Mourino, Nuria; Petrov, Roumen [Department of Materials Science and Engineering, Ghent University, Technologiepark Zwijnaarde 903, B-9052 Ghent (Belgium); Bae, Jin-Ho; Kim, Kisoo [Sheet Products and Process Research Group, POSCO, Jeonnam, 545-090 (Korea, Republic of); Kestens, Leo A.I. [Department of Materials Science and Engineering, Ghent University, Technologiepark Zwijnaarde 903, B-9052 Ghent (Belgium); Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft (Netherlands)

    2011-04-15

    The {gamma}-{alpha} transformation and final microstructure in pipeline steel was studied by carrying out a number of physical simulations of industrial hot rolling schedules. Particularly, the effect of the reheating temperature, deformation and cooling parameters on the transformation temperatures and final grain size were considered with a goal to obtain an appropriate thermo-mechanical processing route which will generate appropriate microstructures for pipeline applications. The CCT diagram of the steel was derived experimentally by means of dilatometric tests. Hot torsion experiments were applied in a multi-deformation cycle at various temperatures in the austenite region to simulate industrial rolling schedules. By variation of the reheating temperature, equivalent strain, and accelerated cooling, different types of microstructures were obtained. It was found that the deformation increases the transformation temperatures whereas the higher cooling rates after deformation decrease them. Post-deformation microstructure consists of fine bainitic-ferrite grains with dispersed carbides and small amount of dispersed martensite/austenite islands which can be controlled by varying the reheating temperature, deformation and post-deformation cooling. The detailed microstructure characteristics obtained from the present work could be used to optimize the mechanical properties, strength and toughness of pipeline steel grades by an appropriate control of the thermo-mechanical processing. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Simulations of Macrosegregation with consideration of inclusion effect in solidifying carbon steels

    International Nuclear Information System (INIS)

    Cao, Y F; Chen, Y; Kang, X H; Fu, P X; Liu, H W; Li, D Z

    2015-01-01

    During casting of steel ingots, the inclusions such as oxide, sulfide will inevitably exist in the melt. These inclusions will flow upward together with light solutes during solidification due to their lower density relative to the steel melt, which therefore causes impacts on the thermo-solutal convection in the melt and final solute distribution. Hence, a macrosegregation model that considers the effects of inclusions on melt flow in the mushy zone is established. Of the new model two important parameters, the inclusion capturing probability by solid, k p , and the original volume fraction, n 0 , are systematically studied in terms of simulations, which shows that decreasing k p or increasing n 0 leads to stronger ascending flow in the melt. And then as a validation example, the model was used to predict the macrosegregation in a 3.3-ton steel ingot. The prediction demonstrates that with consideration of inclusions, the melt convection strength is enhanced and thus the zones of macrosegregation are expanded comparing to simulations without taking account of inclusions. Further comparison with experiment results indicates that a better agreement of the carbon segregation along the centerline of the ingot can be achieved when considering the inclusion buoyancy. (paper)

  13. Passivation and electrochemical behavior of 316L stainless steel in chlorinated simulated concrete pore solution

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Hong, E-mail: luohong@hhu.edu.cn [College of Mechanics and Materials, Hohai University, Nanjing 210098 (China); Su, Huaizhi [State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098,China (China); Dong, Chaofang; Li, Xiaogang [Institute of Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083,China (China)

    2017-04-01

    Highlights: • The pH value play an important role on passive mechanism of stainless steel. • The relationship between Cr/Fe ratio within the passive film and pH is non-linear. • Better corrosion resistance due to high Cr/Fe ratio and molybdates ions. - Abstract: In this paper, the passivation and electrochemical behavior of 316L stainless steel in chlorinated simulated concrete pore solutions at different pH was evaluated by potentiodynamic measurements, electrochemical impedance spectroscopy. The composition of the passive film and surface morphology were investigated by X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), and scanning electron microscopy, respectively. The results reveal that metastable pitting susceptibility, stable pitting corrosion, and composition of the passive film are influenced by pH value. After long time immersion, a bilayer structure passive film can be formed in this environment. The appearance of molybdates on the outermost surface layer, further enhancing the stability of the passive film. Moreover, the good pitting corrosion resistance of 316L stainless steel in simulated concrete pore solution without carbonated is mainly due to the presence of high Cr/Fe ratio and molybdates ions within the passive film.

  14. Experiment and simulation analysis of roll-bonded Q235 steel plate

    International Nuclear Information System (INIS)

    Zhao, G.; Huang, Q.; Zhou, C.; Zhang, Z.; Ma, L.; Wang, X.

    2016-01-01

    Heavy-gauge Q235 steel plate was roll bonded, and the process was simulated using MARC software. Ultrasonic testing results revealed the presence of cracks and lamination defects in an 80-mm clad steel sheet, especially at the head and tail of the steel plate. There were non-uniform ferrite + pearlite microstructures and unbound areas at a bond interface. Through scanning electron microscopy analysis, long cracks and additional inclusions in the cracks were observed at the interface. A fracture analysis revealed non-uniform inclusions that pervaded the interface. Moreover, MARC simulations demonstrated that there was little equivalent strain at the centre of the slab during the first rolling pass. The equivalent centre increased to 0.5 by the fourth rolling pass. Prior to the final pass, the equivalent strain was not consistent across the thickness direction, preventing bonding interfaces from forming consistent deformation and decreasing the residual stress. The initial rolling reduction rate should not be very small (e.g. 5%) as it is averse to the coordination of rolling deformation. Such rolling processes are averse to the rolling bond. (Author)

  15. Passivation and electrochemical behavior of 316L stainless steel in chlorinated simulated concrete pore solution

    International Nuclear Information System (INIS)

    Luo, Hong; Su, Huaizhi; Dong, Chaofang; Li, Xiaogang

    2017-01-01

    Highlights: • The pH value play an important role on passive mechanism of stainless steel. • The relationship between Cr/Fe ratio within the passive film and pH is non-linear. • Better corrosion resistance due to high Cr/Fe ratio and molybdates ions. - Abstract: In this paper, the passivation and electrochemical behavior of 316L stainless steel in chlorinated simulated concrete pore solutions at different pH was evaluated by potentiodynamic measurements, electrochemical impedance spectroscopy. The composition of the passive film and surface morphology were investigated by X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), and scanning electron microscopy, respectively. The results reveal that metastable pitting susceptibility, stable pitting corrosion, and composition of the passive film are influenced by pH value. After long time immersion, a bilayer structure passive film can be formed in this environment. The appearance of molybdates on the outermost surface layer, further enhancing the stability of the passive film. Moreover, the good pitting corrosion resistance of 316L stainless steel in simulated concrete pore solution without carbonated is mainly due to the presence of high Cr/Fe ratio and molybdates ions within the passive film.

  16. The corrosion behavior of steel exposed to a DC electric field in the simulated wet-dry cyclic environment

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Nianwei [Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090 (China); Department of Materials Science, Fudan University, Shanghai 200433 (China); Chen, Qimeng [Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090 (China); Zhang, Junxi, E-mail: zhangjunxi@shiep.edu.cn [Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090 (China); Zhang, Xin; Ni, Qingzhao [Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090 (China); Jiang, Yiming; Li, Jin [Department of Materials Science, Fudan University, Shanghai 200433 (China)

    2017-05-01

    The corrosion of steel exposed under a direct current (DC) electric field during simulated wet-dry cycles was investigated using weight gain, electrochemical tests, X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The results show that the steel exposed to a DC electric field exhibits a higher corrosion rate than those exposed under no DC electric field. The higher the DC electric field intensity, the higher the corrosion rate of steel. The XRD and SEM analyses indicate that more γ-FeOOH and cracks appear in the rust formed on steel exposed to the DC electric field. The porous γ-FeOOH, formation and expansion of cracks enhance the transfer of oxygen and corrosion products, thereby accelerating corrosion of steel exposed to DC electric field. - Highlights: • Effect of DC electric field on the corrosion of steel in wet/dry cycles was studied. • DC electric field accelerates the steel corrosion in wet/dry cyclic processes. • More γ-FeOOH is generated on the surface of steel exposed under a DC electric field. • More cracks appear in the rust formed on the steel exposed under a DC electric filed.

  17. The corrosion behavior of steel exposed to a DC electric field in the simulated wet-dry cyclic environment

    International Nuclear Information System (INIS)

    Dai, Nianwei; Chen, Qimeng; Zhang, Junxi; Zhang, Xin; Ni, Qingzhao; Jiang, Yiming; Li, Jin

    2017-01-01

    The corrosion of steel exposed under a direct current (DC) electric field during simulated wet-dry cycles was investigated using weight gain, electrochemical tests, X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The results show that the steel exposed to a DC electric field exhibits a higher corrosion rate than those exposed under no DC electric field. The higher the DC electric field intensity, the higher the corrosion rate of steel. The XRD and SEM analyses indicate that more γ-FeOOH and cracks appear in the rust formed on steel exposed to the DC electric field. The porous γ-FeOOH, formation and expansion of cracks enhance the transfer of oxygen and corrosion products, thereby accelerating corrosion of steel exposed to DC electric field. - Highlights: • Effect of DC electric field on the corrosion of steel in wet/dry cycles was studied. • DC electric field accelerates the steel corrosion in wet/dry cyclic processes. • More γ-FeOOH is generated on the surface of steel exposed under a DC electric field. • More cracks appear in the rust formed on the steel exposed under a DC electric filed.

  18. Computer Simulation of the Formation of Non-Metallic Precipitates During a Continuous Casting of Steel

    Directory of Open Access Journals (Sweden)

    Kalisz D.

    2016-03-01

    Full Text Available The authors own computer software, based on the Ueshima mathematical model with taking into account the back diffusion, determined from the Wołczyński equation, was developed for simulation calculations. The applied calculation procedure allowed to determine the chemical composition of the non-metallic phase in steel deoxidised by means of Mn, Si and Al, at the given cooling rate. The calculation results were confirmed by the analysis of samples taken from the determined areas of the cast ingot. This indicates that the developed computer software can be applied for designing the steel casting process of the strictly determined chemical composition and for obtaining the required non-metallic precipitates.

  19. Corrosion behaviour of AISI 204Cu and AISI 304 stainless steels in simulated pore solution

    Energy Technology Data Exchange (ETDEWEB)

    Kocijan, Aleksandra [Institute of Metals and Technology, Ljubljana (Slovenia)

    2013-10-15

    The evolution of the passive films on AISI 204Cu and AISI 304 stainless steels in simulated pore solution for steel reinforcements in concrete, and with and without the addition of chloride, was studied using cyclic voltammetry and potentiodynamic measurements. The passive layers were studied at open-circuit potential by means of X-ray photoelectron spectroscopy. The passive films on both materials predominantly contained Cr-oxides, whereas the Fe-species were markedly depleted. Mn-enrichment was also observed. The addition of chloride ions did not have a significant influence on the composition of the passive layers. The surface morphology of the products formed on the surface of both investigated materials at open-circuit potential and at high over-potentials in the presence of chloride was studied using scanning electron microscopy. (orig.)

  20. Large eddy simulation and combustion instabilities; Simulation des grandes echelles et instabilites de combustion

    Energy Technology Data Exchange (ETDEWEB)

    Lartigue, G.

    2004-11-15

    The new european laws on pollutants emission impose more and more constraints to motorists. This is particularly true for gas turbines manufacturers, that must design motors operating with very fuel-lean mixtures. Doing so, pollutants formation is significantly reduced but the problem of combustion stability arises. Actually, combustion regimes that have a large excess of air are naturally more sensitive to combustion instabilities. Numerical predictions of these instabilities is thus a key issue for many industrial involved in energy production. This thesis work tries to show that recent numerical tools are now able to predict these combustion instabilities. Particularly, the Large Eddy Simulation method, when implemented in a compressible CFD code, is able to take into account the main processes involved in combustion instabilities, such as acoustics and flame/vortex interaction. This work describes a new formulation of a Large Eddy Simulation numerical code that enables to take into account very precisely thermodynamics and chemistry, that are essential in combustion phenomena. A validation of this work will be presented in a complex geometry (the PRECCINSTA burner). Our numerical results will be successfully compared with experimental data gathered at DLR Stuttgart (Germany). Moreover, a detailed analysis of the acoustics in this configuration will be presented, as well as its interaction with the combustion. For this acoustics analysis, another CERFACS code has been extensively used, the Helmholtz solver AVSP. (author)

  1. Internet-based simulation of resource requirement of buildings; Internetbasierte Simulation des Ressourcenbedarfs von Bauwerken

    Energy Technology Data Exchange (ETDEWEB)

    Neuberg, F.; Rank, E. [Technische Univ. Muenchen, Lehrstuhl fuer Bauinformatik, Muenchen (Germany); Ekkerlein, C.; Faulstich, M. [Technische Univ. Muenchen, Lehrstuhl fuer Wasserguete- und Abfallwirtschaft, Garching (Germany)

    2002-12-01

    Due to the long life cycle of a building the expenses for usage and maintenance are very high compared to those for the construction, only. About 1/3 of the total energy demand in Germany is used for heating, air-conditioning and hot water supply in buildings. In addition the building wastes resulting for disposal represent a quantitatively enormous material flow. As the most significant decisions are made in early planning steps it is very important to enable planners to estimate the energy demand, resource requirement and ecological impact of different scenarios at this stage. Nowadays more and more architects and engineers use CAD software, like the Architectural Desktop from Autodesk, supporting the generation of three dimensional product models. One prominent model being now well established in the building industry is defined by the Industry Foundation Classes (IFC). This model is also the starting point of our resource oriented design system. To get a basis for a comparative assessment of different design variants it is first necessary to augment the product model with information on resource consumption of the used materials. Therefore a database server accessible via the Internet is developed within our research project providing a service for planners to extend their product model with information necessary for life cycle assessment (LCA) and building energy simulation (EnEV). The data exchange format for the property sets is ifcXML. In our presentation the general software concept together with first simulation tools will be discussed. (orig.)

  2. Simulation of crack propagation in steel plate with strain softening model

    Energy Technology Data Exchange (ETDEWEB)

    Chan, O.B.; Elwi, A.E.; Grondin, G.Y.

    2006-05-15

    A new material model for simulating the fracture behaviour of structural steel was presented. Recent research on crack initiation and continuum damage mechanics was presented. A modified continuum damage model was also evaluated. Strain softening elements were then used to simulate material cracks in a steel structure. The analysis then compared load versus displacement and load versus clip-gauge displacement curves from various different experimental and numerical studies. A finite element analysis technique was used to simulate the fracture behaviour of 3-points bending specimens. Results of the analysis showed that the model predicted 90 per cent of the load and stress intensity factor at fracture initiation. A BE 365 electric shovel boom was used in the study to simulate fracture behaviour. Coupon test specimens were used to validate analysis predictions. It was concluded that the model was able to reduce the stiffness of the boom when the softening element reached yield strength limits during fracture initiation. 29 refs., 12 tabs., 58 figs.

  3. Effects of simulated inflammation on the corrosion of 316L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, Emily K.; Brooks, Richard P. [Department of Biomedical Engineering, State University of New York at Buffalo (United States); Ehrensberger, Mark T., E-mail: mte@buffalo.edu [Department of Biomedical Engineering, State University of New York at Buffalo (United States); Department of Orthopaedics, State University of New York at Buffalo (United States)

    2017-02-01

    Stainless steel alloys, including 316L, find use in orthopaedics, commonly as fracture fixation devices. Invasive procedures involved in the placement of these devices will provoke a local inflammatory response that produces hydrogen peroxide (H{sub 2}O{sub 2}) and an acidic environment surrounding the implant. This study assessed the influence of a simulated inflammatory response on the corrosion of 316L stainless steel. Samples were immersed in an electrolyte representing either normal or inflammatory physiological conditions. After 24 h of exposure, electrochemical impedance spectroscopy (EIS) and inductively coupled plasma mass spectroscopy (ICPMS) were used to evaluate differences in corrosion behavior and ion release induced by the inflammatory conditions. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) were used to evaluate surface morphology and corrosion products formed on the sample surface. Inflammatory conditions, involving the presence of H{sub 2}O{sub 2} and an acidic pH, significantly alter the corrosion processes of 316L stainless steel, promoting aggressive and localized corrosion. It is demonstrated that particular consideration should be given to 316L stainless steel implants with crevice susceptible areas (ex. screw-head/plate interface), as those areas may have an increased probability of rapid and aggressive corrosion when exposed to inflammatory conditions. - Highlights: • The corrosion of 316L exposed to simulated inflammation is examined. • Inflammation is replicated with an acidic electrolyte containing hydrogen peroxide. • Inflammatory conditions increase 316L corrosion compared to normal conditions. • Accelerated corrosion under inflammation is likely due to crevice corrosion. • Care should be taken using 316L in devices with crevice susceptible areas.

  4. Simulation applied to innovative waste management options; Simulation appliquee aux options innovantes de gestion des dechets

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-10-01

    The aim of this workshop is to share experience and methods in the domains of neutronics, spallation, thermo-hydraulics, corrosion, materials, mechanics; to define the needs for the other domains in order to improve the evaluation of concepts: ADS, MSR, Gas cooled reactors; and to determine the necessity or not to couple codes and tools for the concepts studied in the frame of GEDEON activities. This document groups together the transparencies of 6 presentations given at this workshop: design and performances of CEA spallation targets; simulation of spallation; the neutronic benchmark on the Megapie spallation target; the core physics of fast spectrum gas cooled reactors; the study and modeling of the thermal-mechanical behaviour of composite fuel in reactor. (J.S.)

  5. Numerical Simulation of Interactions between Corrosion Pits on Stainless Steel under Loading Conditions

    International Nuclear Information System (INIS)

    Wang, Haitao; Han, En-Hou

    2017-01-01

    The interactions between corrosion pits on stainless steel under loading conditions are studied by using a cellular automata model coupled with finite element method at a mesoscopic scale. The cellular automata model focuses on a metal/film/electrolyte system, including anodic dissolution, passivation, diffusion of hydrogen ions and salt film hydrolysis. The Chopard block algorithm is used to improve the diffusion simulation efficiency. The finite element method is used to calculate the stress concentration on the pit surface during pit growth, and the effect of local stress and strain on anodic current is obtained by using the Gutman model, which is used as the boundary conditions of the cellular automata model. The transient current characteristics of the interactions between corrosion pits under different simulation factors including the breakdown of the passive film at the pit mouth and the diffusion of hydrogen ions are analyzed. The analysis of the pit stability product shows that the simulation results are close to the experimental conclusions.

  6. Numerical Simulation of Interactions between Corrosion Pits on Stainless Steel under Loading Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haitao; Han, En-Hou [Chinese Academy of Sciences, Shenyang (China)

    2017-04-15

    The interactions between corrosion pits on stainless steel under loading conditions are studied by using a cellular automata model coupled with finite element method at a mesoscopic scale. The cellular automata model focuses on a metal/film/electrolyte system, including anodic dissolution, passivation, diffusion of hydrogen ions and salt film hydrolysis. The Chopard block algorithm is used to improve the diffusion simulation efficiency. The finite element method is used to calculate the stress concentration on the pit surface during pit growth, and the effect of local stress and strain on anodic current is obtained by using the Gutman model, which is used as the boundary conditions of the cellular automata model. The transient current characteristics of the interactions between corrosion pits under different simulation factors including the breakdown of the passive film at the pit mouth and the diffusion of hydrogen ions are analyzed. The analysis of the pit stability product shows that the simulation results are close to the experimental conclusions.

  7. A cohesive zone model to simulate the hydrogen embrittlement effect on a high-strength steel

    Directory of Open Access Journals (Sweden)

    G. Gobbi

    2016-01-01

    Full Text Available The present work aims to model the fracture mechanical behavior of a high-strength low carbon steel, AISI 4130 operating in hydrogen contaminated environment. The study deals with the development of 2D finite element cohesive zone model (CZM reproducing a toughness test. Along the symmetry plane over the crack path of a C(T specimen a zero thickness layer of cohesive elements are implemented in order to simulate the crack propagation. The main feature of this kind of model is the definition of a traction-separation law (TSL that reproduces the constitutive response of the material inside to the cohesive elements. Starting from a TSL calibrated on hydrogen non-contaminated material, the embrittlement effect is simulated by reducing the cohesive energy according to the total hydrogen content including the lattice sites (NILS and the trapped amount. In this perspective, the proposed model consists of three steps of simulations. First step evaluates the hydrostatic pressure. It drives the initial hydrogen concentration assigned in the second step, a mass diffusion analysis, defining in this way the contribution of hydrogen moving across the interstitial lattice sites. The final stress analysis, allows getting the total hydrogen content, including the trapped amount, and evaluating the new crack initiation and propagation due to the hydrogen presence. The model is implemented in both plane strain and plane stress configurations; results are compared in the discussion. From the analyses, it resulted that hydrogen is located only into lattice sites and not in traps, and that the considered steel experiences a high hydrogen susceptibility. By the proposed procedure, the developed numerical model seems a reliable and quick tool able to estimate the mechanical behavior of steels in presence of hydrogen.

  8. Microscopic analysis and simulation of check-mark stain on the galvanized steel strip

    Science.gov (United States)

    So, Hongyun; Yoon, Hyun Gi; Chung, Myung Kyoon

    2010-11-01

    When galvanized steel strip is produced through a continuous hot-dip galvanizing process, the thickness of adhered zinc film is controlled by plane impinging air gas jet referred to as "air-knife system". In such a gas-jet wiping process, stain of check-mark or sag line shape frequently appears. The check-mark defect is caused by non-uniform zinc coating and the oblique patterns such as "W", "V" or "X" on the coated surface. The present paper presents a cause and analysis of the check-mark formation and a numerical simulation of sag lines by using the numerical data produced by Large Eddy Simulation (LES) of the three-dimensional compressible turbulent flow field around the air-knife system. It was found that there is alternating plane-wise vortices near the impinging stagnation region and such alternating vortices move almost periodically to the right and to the left sides on the stagnation line due to the jet flow instability. Meanwhile, in order to simulate the check-mark formation, a novel perturbation model has been developed to predict the variation of coating thickness along the transverse direction. Finally, the three-dimensional zinc coating surface was obtained by the present perturbation model. It was found that the sag line formation is determined by the combination of the instantaneous coating thickness distribution along the transverse direction near the stagnation line and the feed speed of the steel strip.

  9. The Importance of Thermophysical Properties of Steels for the Numerical Simulation of a Concasting Process

    Directory of Open Access Journals (Sweden)

    Frantisek KAVICKA

    2010-12-01

    Full Text Available The thermophysical properties of steels have significant influence on the actual concasting process, and on the accuracy of its numerical simulation and optimization. The determination of these properties (heat conductivity, specific heat capacity and density in the solid and liquid states often requires more time than the actual numerical calculation of the temperature fields of a continuously cast steel billet, cylinder or slab (generally a concasting. The influence of individual properties should be neither under- nor over-estimated. Therefore, an analysis/parametric study of these thermophysical properties was conducted. The order of importance within the actual process and the accuracy of simulation and optimization were also determined. Individual properties, which, in some cases, were obtained from tables, and in others experimentally, were substituted by an approximation using orthogonal polynomials. The accuracy of each polynomial is dependent on the precision of individual values. The order of significance of individual thermophysical properties was determined with respect to the metallurgical length. The analysis was performed by means of a so-called calculation experiment, i.e. by means of the original and universal numerical concasting model developed by the authors of this paper. It is convenient to conduct such an analysis in order to facilitate the simulation of each individual case of concasting, thus enhancing the process of optimization.

  10. Numerical Simulation of Hysteretic Live Load Effect in a Soil-Steel Bridge

    Directory of Open Access Journals (Sweden)

    Sobótka Maciej

    2014-03-01

    Full Text Available The paper presents numerical simulation of hysteretic live load effect in a soil-steel bridge. The effect was originally identified experimentally by Machelski [1], [2]. The truck was crossing the bridge one way and the other in the full-scale test performed. At the same time, displacements and stress in the shell were measured. The major conclusion from the research was that the measured quantities formed hysteretic loops. A numerical simulation of that effect is addressed in the present work. The analysis was performed using Flac finite difference code. The methodology of solving the mechanical problems implemented in Flac enables us to solve the problem concerning a sequence of load and non-linear mechanical behaviour of the structure. The numerical model incorporates linear elastic constitutive relations for the soil backfill, for the steel shell and the sheet piles, being a flexible substructure for the shell. Contact zone between the shell and the soil backfill is assumed to reflect elastic-plastic constitutive model. Maximum shear stress in contact zone is limited by the Coulomb condition. The plastic flow rule is described by dilation angle ψ = 0. The obtained results of numerical analysis are in fair agreement with the experimental evidence. The primary finding from the performed simulation is that the slip in the interface can be considered an explanation of the hysteresis occurrence in the charts of displacement and stress in the shell.

  11. Pitting growth rate in carbon steel exposed to simulated radioactive waste

    International Nuclear Information System (INIS)

    Zapp, P.E.

    1995-01-01

    Dilute high-level radioactive waste slurries can induce pitting corrosion in carbon steel tanks in which such waste is stored and processed. The waste is normally maintained with closely monitored nitrite and hydroxide concentrations known to prevent the initiation of pitting. Coupon immersion are being conducted in laboratory simulants of waste to determine the probability and growth rate of pitting in steel in the event of below-limits nitrite concentrations. Sets of about 36 carbon steel coupons have been immersed in known corrosive conditions (nitrite < 5% of the established limit) at a temperature of 50 C. Three sets have been removed from testing after 64, 150, and 350 days of immersion. The long immersion times introduced variability in the exposure conditions due to the evaporation and replenishment of solution. The deepest corrosive attack was measured one each coupon by optical microscopy. The deepest pits were ranked and analyzed as a type 1 extreme value distribution to extrapolate from the coupon population to the maximum pit depths in a waste tank structure. The data were compared to a power law for pit growth, although the deepest pits did not increase monotonically with time in the limited data set

  12. Pitting growth rate in carbon steel exposed to simulated radioactive waste

    International Nuclear Information System (INIS)

    Zapp, P.E.

    1996-06-01

    Dilute high-level radioactive waste slurries can induce pitting corrosion in carbon steel tanks in which such waste is stored and processed. The waste is normally maintained with closely monitored nitrite and hydroxide concentrations known to prevent the initiation of pitting. Coupon immersion tests are being conducted in laboratory simulants of waste to determine the probability and growth rate of pitting in steel in the event of out-of-limits nitrite concentrations. Sets of about 36 carbon steel coupons have been immersed in known corrosive conditions (nitrite < 5 per cent of the established limit) at a temperature of 50 degrees C. Three sets have been removed from testing after 64, 150, and 350 days of immersion. The long immersion times introduced variability in the exposure conditions due to the evaporation and replenishment of solution. The deepest corrosive attack was measured on each coupon by optical microscopy. The deepest pits were ranked and analyzed as a type 1 extreme value distribution to extrapolate from the coupon population to the maximum expected pit depths in a waste tank structure. The data were compared to a power law for pit growth, although the deepest pits did not increase monotonically with time in the limited data set

  13. Electrochemical Corrosion Behavior of Low Carbon I-Beam Steels In Simulated Yucca Mountain Repository Environment

    Energy Technology Data Exchange (ETDEWEB)

    Arjunan, Venugopal; Lamb, Joshua; Chandra, Dhanesh; Daemen, Jack; Jones, Denny A.; Engelhard, Mark H.; Lea, Alan S.

    2005-04-01

    The electrochemical corrosion behavior of low carbon steel was examined in a simulated Yucca Mountain (YM) ground water by varying the electrolyte concentration and temperature under aerated and deaerated conditions. The results show that in deaerated conditions, the corrosion rate is low in the order of 0.6 to 4.5mpy, between 25 to 85 C, respectively. However, in aerated conditions the measured rates were expectedly very high, in the order of 3-55mpy in the above mentioned temperature levels. The rates initially increased up to 45 C, and a decreasing trend was observed with further increase in temperature from 65 to 85 C. The maximum corrosion rate was occurred at 45 C (54.5mpy). The low corrosion rates observed in all deaerated conditions, and in aerated solutions at higher temperatures were due to the preferential adsorption of Mg-species on the steel surface, as identified by XPS analyses. The results also indicate possible localized corrosion behavior of carbon steel in aerated conditions up to 45 C.

  14. Electrochemical Corrosion Behavior of Low Carbon I-Beam Steels In Simulated Yucca Mountain Repository Environment

    International Nuclear Information System (INIS)

    Arjunan, Venugopal; Lamb, Joshua; Chandra, Dhanesh; Daemen, Jack; Jones, Denny A.; Engelhard, Mark H.; Lea, Alan S.

    2005-01-01

    The electrochemical corrosion behavior of low carbon steel was examined in a simulated Yucca Mountain (YM) ground water by varying the electrolyte concentration and temperature under aerated and deaerated conditions. The results show that in deaerated conditions, the corrosion rate is low in the order of 0.6 to 4.5mpy, between 25 to 85 C, respectively. However, in aerated conditions the measured rates were expectedly very high, in the order of 3-55mpy in the above mentioned temperature levels. The rates initially increased up to 45 C, and a decreasing trend was observed with further increase in temperature from 65 to 85 C. The maximum corrosion rate was occurred at 45 C (54.5mpy). The low corrosion rates observed in all deaerated conditions, and in aerated solutions at higher temperatures were due to the preferential adsorption of Mg-species on the steel surface, as identified by XPS analyses. The results also indicate possible localized corrosion behavior of carbon steel in aerated conditions up to 45 C

  15. Oxidation of iron and steels by carbon dioxide under pressure (1962); Oxydation du fer et des aciers par l'anhydride carbonique sous pression (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Colombie, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    After having developed one of the first thermo-balances to operate under pressure, we have studied the influence of the pressure on the corrosion of iron and steels by carbon dioxide. The corrosion was followed by three different methods simultaneously: by the oxidation kinetics, by micrographs, and by radiocrystallography. We have been able to show that the influence of the pressure is not negligible and we have provided much experimental evidence: oxidation kinetics, micrographic aspects, surface precipitation of carbon, metal carburization, the texture of the magnetite layer. All these phenomena are certainly modified by changes in the carbon dioxide pressure. In order to interpret most of our results we have been led to believe that the phenomenon of corrosion by CO{sub 2} depends on secondary reactions localised at the oxide-gas interface. This would constitute a major difference between the oxidation by CO{sub 2} and that by oxygen. (author) [French] Apres avoir etudie et mis au point une des premieres thermobalances fonctionnant sous pression, nous avons etudie l'influence de la pression sur la corrosion du fer et des aciers par l'anhydride carbonique. Notre etude a ete conduite simultanement sur trois plans differents: etude des cinetiques d'oxydation, etude micrographique et etude radiocristallographique. Nous avons pu montrer que l'influence de la pression n'etait pas negligeable et nous en avons fourni un faisceau de preuves experimentales important: cinetiques d'oxydation, aspect micrographique, precipitation superficielle de carbone, carburation du metal, texture de la couche de magnetite. Tous ces phenomenes sont sans aucun doute modifies par une variation de pression du gaz carbonique. Pour interpreter la plupart de nos resultats, nous avons ete conduits a penser que le phenomene de corrosion par CO{sub 2} etait tributaire de reactions secondaires localisees a l'interface oxyde-gaz. Ce serait la une des differences fondamentales entre l'oxydation par

  16. Revealing microstructural and mechanical characteristics of cold-drawn pearlitic steel wires undergoing simulated galvanization treatment

    Energy Technology Data Exchange (ETDEWEB)

    Fang Feng, E-mail: fangfeng@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); Hu Xianjun [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); Jiangsu Sha-Steel Group, Zhangjiagang City, Jiangsu Province 215625 (China); Chen Shaohui [Jiangsu Sha-Steel Group, Zhangjiagang City, Jiangsu Province 215625 (China); Xie Zonghan [School of Engineering, Edith Cowen University, Joondalup, WA 6027 (Australia); Jiang Jianqing [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Annealing time on microstructure and mechanical properties of cold-drawn steel wires were studied. Black-Right-Pointing-Pointer Exothermic peak in cold-drawn wire was resulting from the spheroidization of lamellar cementite. Black-Right-Pointing-Pointer Spheroidization of lamellar cementite is the main effect for torsion property of wires after annealing. - Abstract: Spheroidization of lamellar cementite often occurs in cold-drawn pearlitic steel wires during galvanizing treatment, leading to the degradation of mechanical properties. Therefore, it is important to understand effects of galvanization process on microstructure and mechanical properties of cold-drawn wires. In this paper, cold-drawn steel wires were fabricated by cold drawing pearlitic steel rods from 13 mm to 6.9 mm in diameter. Thermal annealing at 450 Degree-Sign C was used to simulate galvanizing treatment of steel wires. Tensile strength, elongation and torsion laps of steel rods and wires with, and without, annealing treatment were determined. Microstructure was observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, differential scanning calorimetry (DSC) was used to probe the spheroidization temperature of cementite. Experimental results showed that tensile strength of wires increased from 1780 MPa to 1940 MPa for annealing <5 min, and then decreased. Tensile strength became constant for annealing >10 min. Elongation of wires decreased for annealing <2.5 min, and then recovered slightly. It approached a constant value for annealing >5 min. Tensile strength and elongation of wires were both influenced by the strain age hardening and static recovery processes. Notably, torsion laps of wires hardly changed when annealing time was less than 2.5 min, and then decreased rapidly. Its value became constant when the hold time is greater than 10 min. Lamellar cementite began to spheroidize at annealing >2.5 min

  17. Microstructural investigation of the heat-affected zone of simulated welded joint of P91 steel

    Directory of Open Access Journals (Sweden)

    T. Vuherer

    2013-07-01

    Full Text Available In the process of testing real components exposed to elevated temperature, it is not possible to neglect cracks. The most significant cracks can be induced by welding, which is applied for joining of structural components. Pressure equipment in service is also exposed to high pressure and high stresses. Materials for their manufacturing are designed to resist high stress at elevated temperature, and to meet requirements regarding creep resistance. The objective of this study is to investigate microstructure of different regions of the heat affected zone in T/P91 steels by using thermal simulation instead of welding.

  18. Optimal Research and Numerical Simulation for Scheduling No-Wait Flow Shop in Steel Production

    Directory of Open Access Journals (Sweden)

    Huawei Yuan

    2013-01-01

    Full Text Available This paper considers the m-machine flow shop scheduling problem with the no-wait constraint to minimize total completion time which is the typical model in steel production. First, the asymptotic optimality of the Shortest Processing Time (SPT first rule is proven for this problem. To further evaluate the performance of the algorithm, a new lower bound with performance guarantee is designed. At the end of the paper, numerical simulations show the effectiveness of the proposed algorithm and lower bound.

  19. Simulation of Distortion and Residual Stress Development During Heat Treatment of Steel Castings

    Energy Technology Data Exchange (ETDEWEB)

    Beckermann, Christoph; Carlson, Kent

    2011-07-22

    of the Navy-C ring (a classical test shape for heat treatment experiments) for several carbon and low alloy steels in order to generate data necessary to validate the code. The predicted distortions were in reasonable agreement with the experimentally measured values. However, the final distortions in the castings were small, making it difficult to determine how accurate the predictions truly are. It is recommended that further validation of the software be performed with the aid of additional experiments with large production steel castings that experience significant heat treatment distortions. It is apparent from this research that the mechanical properties of the bonded sand used for cores and sand molds are key in producing accurate stress simulation results. Because of this, experiments were performed to determine the temperature-dependent elastic modulus of a resin-bonded sand commonly utilized in the steel casting industry. The elastic modulus was seen to vary significantly with heating and cooling rates. Also, the retained room temperature elastic modulus after heating was seen to degrade significantly when the sand was heated above 125°C. The elastic modulus curves developed in this work can readily be utilized in casting simulation software. Additional experiments with higher heating rates are recommended to determine the behavior of the elastic modulus in the sand close to the mold-metal interface. The commercial heat treatment residual stress and distortion code, once fully validated, is expected to result in an estimated energy savings of 2.15 trillion BTU's/year. Along with these energy savings, reduction of scrap and improvement in casting yield will result in a reduction of the environmental emissions associated with the melting and pouring of the metal which will be saved as a result of this technology.

  20. Simulation of the lateral pole-impact on a crash simulation system; Simulation des seitlichen Pfahlaufpralls auf einer Katapultanlage

    Energy Technology Data Exchange (ETDEWEB)

    Hoegner, C.; Gajewski, M.; Zippel, I. [ACTS GmbH und Co. KG, Sailauf (Germany)

    2001-07-01

    The test set-up for the simulation of a lateral pole impact has the following characteristics: - Simulation of pole impact procedures Euro-NCAP and others - Very realistic reproduction of the deformation performance of side panels (with simulated or original part assemblies) - Consideration of the dynamic displacement of the cant rail - Seat displacement and deformation - Realistic depiction of the vehicle displacement (i.e. car-to-pole) - Test velocity: up to 50 km/h - Intrusion: up to 550 mm (more also possible on demand) - Pole diameter 254 mm (variable). This test system design results in variable set-up possibilities: - Test-set up possible from very simple (on the basis of simulation data without real parts) to very complex (use of side panels and interior door trim) - Support of different protection systems (window bag and side bag) - A maximum of two occupants feasible (set up weight max. 300 kg) - Optimal camera perspectives, stationary or onboard - Front as well as rear side impact simulation possible - Front-rear interaction of protection systems feasible (two dummies). A test system has been realised with which the complex process in a lateral pole impact can be simulated with excellent approximation and with relatively simple means. Due to the avoidance of point validation this methodology can be ideally implemented for development tests. (orig.)

  1. Numerical simulation of projectile impact on mild steel armour plates using LS-DYNA, Part II: Parametric studies

    OpenAIRE

    Raguraman, M; Deb, A; Gupta, NK; Kharat, DK

    2008-01-01

    In Part I of the current two-part series, a comprehensive simulation-based study of impact of Jacketed projectiles on mild steel armour plates has been presented. Using the modelling procedures developed in Part I, a number of parametric studies have been carried out for the same mild steel plates considered in Part I and reported here in Part II. The current investigation includes determination of ballistic limits of a given target plate for different projectile diameters and impact velociti...

  2. Numerical Simulation of Projectile Impact on Mild Steel Armour Platesusing LS-DYNA, Part II: Parametric Studies

    OpenAIRE

    M. Raguraman; A. Deb; N. K. Gupta; D. K. Kharat

    2008-01-01

    In Part I of the current two-part series, a comprehensive simulation-based study of impact of jacketed projectiles on mild steel armour plates has been presented. Using the modelling procedures developed in Part I, a number of parametric studies have been carried out for the same mild steel plates considered in Part I and reported here in Part II. The current investigation includes determination of ballistic limits of a given target plate for different projectile diameters and impact velociti...

  3. Electrocoagulation of simulated reactive dyebath effluent with aluminum and stainless steel electrodes.

    Science.gov (United States)

    Arslan-Alaton, Idil; Kabdaşli, Işik; Vardar, Burcu; Tünay, Olcay

    2009-05-30

    Reactive dyebath effluents are ideal candidates for electrocoagulation due to their intensive color, medium strength, recalcitrant COD and high electrolyte (NaCl) content. The present study focused on the treatability of simulated reactive dyebath effluent (COD(o)=300 mg/L; color in terms of absorbance values A(o,436)=0.532 cm(-1), A(o,525)=0.693 cm(-1) and A(o,620)=0.808 cm(-1)) employing electrocoagulation with aluminum and stainless steel electrodes. Optimization of critical operating parameters such as initial pH (pH(o) 3-11), applied current density (J(c)=22-87 mA/cm(2)) and electrolyte type (NaCl or Na(2)SO(4)) improved the overall treatment efficiencies resulting in effective decolorization (99% using stainless steel electrodes after 60 min, 95% using aluminum electrodes after 90 min electrocoagulation) and COD abatement (93% with stainless steel electrodes after 60 min, 86% with aluminum electrodes after 90 min of reaction time). Optimum electrocoagulation conditions were established as pH(o) 5 and J(c)=22 mA/cm(2) for both electrode materials. The COD and color removal efficiencies also depended on the electrolyte type. No in situ, surplus adsorbable organically bound halogens (AOX) formation associated with the use of NaCl as the electrolyte during electrocoagulation was detected. An economical evaluation was also carried out within the frame of the study. It was demonstrated that electrocoagulation of reactive dyebath effluent with aluminum and stainless steel electrodes was a considerably less electrical energy-intensive, alternative treatment method as compared with advanced chemical oxidation techniques.

  4. Optimization of cladding parameters for resisting corrosion on low carbon steels using simulated annealing algorithm

    Science.gov (United States)

    Balan, A. V.; Shivasankaran, N.; Magibalan, S.

    2018-04-01

    Low carbon steels used in chemical industries are frequently affected by corrosion. Cladding is a surfacing process used for depositing a thick layer of filler metal in a highly corrosive materials to achieve corrosion resistance. Flux cored arc welding (FCAW) is preferred in cladding process due to its augmented efficiency and higher deposition rate. In this cladding process, the effect of corrosion can be minimized by controlling the output responses such as minimizing dilution, penetration and maximizing bead width, reinforcement and ferrite number. This paper deals with the multi-objective optimization of flux cored arc welding responses by controlling the process parameters such as wire feed rate, welding speed, Nozzle to plate distance, welding gun angle for super duplex stainless steel material using simulated annealing technique. Regression equation has been developed and validated using ANOVA technique. The multi-objective optimization of weld bead parameters was carried out using simulated annealing to obtain optimum bead geometry for reducing corrosion. The potentiodynamic polarization test reveals the balanced formation of fine particles of ferrite and autenite content with desensitized nature of the microstructure in the optimized clad bead.

  5. ''Simulation of the testing of cladded steel pieces by focussed ultrasonic transducers''

    International Nuclear Information System (INIS)

    Nadal, J.

    1996-01-01

    The inner surface of vessels of pressurized water reactor is protected from corrosion by a stainless steel cladding hot-layer in many cuts. Therefore, the surface irregularities generate spurious echoes that can either mask or be misinterpreted for echoes from possible defects. Probes are calibrated on a specific reflector (side drilled holes in a steel block). The echo arising from it is used as a reference to quantify echoes measured during an examination. The study aims at simulating echographs of the vessel inspection so as to help the analysis of actual measurements. Three models are developed to compute echoes from cladding surface irregularities, echoes from planar defects and the reference echo, respectively. The radiated field is modelled using the Rayleigh integral, the integration of the incident beam with the cladded surface is treated under Kirchhoffs approximation and the reception of reflected waves involves reciprocity between radiation and reception. An extra physical hypothesis allows a fast algorithm to be developed for simulating the Bscan image obtained by transducer scan. The reference echo is also computed under Kirchhoffs approximation. The field refracted inside the material is modelled by an extension of the Rayleigh integral using the geometrical optics approximation. The model for computing diffracted echoes from crack tips is based upon the Geometric Theory of Diffraction. The model for predicting echoes from cladded surface irregularities has been validated by comparing theoretical predictions with experimental measurements. (author)

  6. Numerical simulation on multiple pouring process for a 292 t steel ingot

    Directory of Open Access Journals (Sweden)

    Tu Wutao

    2014-01-01

    Full Text Available A ladle-tundish-mould transportation model considering the entire multiple pouring (MP process is proposed. Numerical simulation is carried out to study the carbon distribution and variation in both the tundish and the mould for making a 292 t steel ingot. Firstly, the fluid flow as well as the heat and mass transfer of the molten steel in the tundish is simulated based on the multiphase transient turbulence model. Then, the carbon mixing in the mould is calculated by using the species concentration at the tundish outlet as the inlet condition during the teeming process. The results show a high concentration of carbon at the bottom and a low concentration of carbon at the top of the mould after a MP process with carbon content high in the first ladle and low in the last ladle. Such carbon concentration distribution would help reduce the negative segregation at the bottom and the positive segregation at the top of the solidified ingot.

  7. Construction Simulation Analysis of 60m-span Concrete Filled Steel Tube arch bridge

    Science.gov (United States)

    Shi, Jing Xian; Ding, Qing Hua

    2018-06-01

    The construction process of the CFST arch bridge is complicated. The construction process not only affects the structural stress in the installation, but also determines the form a bridge and internal force of the bridge. In this paper, a 60m span concrete filled steel tube tied arch bridge is taken as the background, and a three-dimensional finite element simulation model is established by using the MIDAS/Civil bridge structure analysis software. The elevation of the main arch ring, the beam stress, the forces in hanger rods and the modal frequency of the main arch during the construction stage are calculated, and the construction process is simulated and analyzed. Effectively and reasonably guide the construction and ensure that the line and force conditions of the completed bridge meet the design requirements and provides a reliable technical guarantee for the safe construction of the bridge.

  8. Numerical simulation of transformation-induced microscopic residual stress in ferrite-martensite lamellar steel

    International Nuclear Information System (INIS)

    Mikami, Y; Inao, A; Mochizuki, M; Toyoda, M

    2009-01-01

    The effect of transformation-induced microscopic residual stress on fatigue crack propagation behavior of ferrite-martensite lamellar steel was discussed. Fatigue tests of prestrained and non-prestrained specimens were performed. Inflections and branches at ferrite-martensite boundaries were observed in the non-prestrained specimens. On the other hand, less inflections and branches were found in the prestrained specimens. The experimental results showed that the transformation induced microscopic residual stress has influence on the fatigue crack propagation behavior. To estimate the microscopic residual, a numerical simulation method for the calculation of microscopic residual stress stress induced by martensitic transformation was performed. The simulation showed that compressive residual stress was generated in martensite layer, and the result agree with the experimental result that inflections and branches were observed at ferrite-martensite boundaries.

  9. Fatigue mechanisms in an austenitic steel under cyclic loading: Experiments and atomistic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Soppa, E.A., E-mail: ewa.soppa@mpa.uni-stuttgart.de; Kohler, C., E-mail: christopher.kohler@mpa.uni-stuttgart.de; Roos, E., E-mail: eberhard.roos@mpa.uni-stuttgart.de

    2014-03-01

    Experimental investigations on the austenitic stainless steel X6CrNiNb18-10 (AISI – 347) and concomitant atomistic simulations of a FeNi nanocrystalline model system have been performed in order to understand the basic mechanisms of fatigue damage under cyclic loading. Using electron backscatter diffraction (EBSD) the influence of deformation induced martensitic transformation and NbC size distribution on the fatigue crack formation has been demonstrated. The martensite nucleates prevalently at grain boundaries, triple points and at the specimen free surface and forms small (∼1 µm sized) differently oriented grains. The atomistic simulations show the role of regions of a high density of stacking faults for the martensitic transformation.

  10. Behavior of Type 316 stainless steel under simulated fusion reactor irradiation

    International Nuclear Information System (INIS)

    Wiffen, F.W.; Maziasz, P.J.; Bloom, E.E.; Stiegler, J.O.; Grossbeck, M.L.

    1978-05-01

    Fusion reactor irradiation response in alloys containing nickel can be simulated in thermal-spectrum fission reactors, where displacement damage is produced by the high-energy neutrons and helium is produced by the capture of two thermal neutrons in the reactions: 58 Ni + n → 59 Ni + γ; 59 Ni + n → 56 Fe + α. Examination of type 316 stainless steel specimens irradiated in HFIR has shown that swelling due to cavity formation and degradation of mechanical properties are more severe than can be predicted from fast reactor irradiations, where the helium contents produced are far too low to simulate fusion reactor service. Swelling values are greater and the temperature dependence of swelling is different than in the fast reactor case

  11. Simulation of surface profile formation in oxygen laser cutting of mild steel due to combustion cycles

    Energy Technology Data Exchange (ETDEWEB)

    Ermolaev, G V; Kovalev, O B [Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch of Russian Academy of Sciences, Institutskaya Str 4/1, Novosibirsk, 630090 (Russian Federation)

    2009-09-21

    A physicomathematical model of cyclic iron combustion in an oxygen flow during oxygen laser cutting of metal sheets is developed. The combustion front is set into motion by focused laser radiation and a heterogeneous oxidation reaction in oxygen. The burning rate is limited by oxygen supply from the gas phase towards the metal surface, and the interface motion depends on the local temperature. A 3D numerical simulation predicts wavy structures on the metal surface; their linear sizes depend on the scanning speed of the laser beam, the thickness of the produced liquid oxide film and the parameters of the oxygen jet flow. Simulation results help in understanding the mechanism of striation formation during oxygen gas-laser cutting of mild steel and are in qualitative agreement with experimental findings.

  12. Optimization and Simulation of SLM Process for High Density H13 Tool Steel Parts

    Science.gov (United States)

    Laakso, Petri; Riipinen, Tuomas; Laukkanen, Anssi; Andersson, Tom; Jokinen, Antero; Revuelta, Alejandro; Ruusuvuori, Kimmo

    This paper demonstrates the successful printing and optimization of processing parameters of high-strength H13 tool steel by Selective Laser Melting (SLM). D-Optimal Design of Experiments (DOE) approach is used for parameter optimization of laser power, scanning speed and hatch width. With 50 test samples (1×1×1cm) we establish parameter windows for these three parameters in relation to part density. The calculated numerical model is found to be in good agreement with the density data obtained from the samples using image analysis. A thermomechanical finite element simulation model is constructed of the SLM process and validated by comparing the calculated densities retrieved from the model with the experimentally determined densities. With the simulation tool one can explore the effect of different parameters on density before making any printed samples. Establishing a parameter window provides the user with freedom for parameter selection such as choosing parameters that result in fastest print speed.

  13. Molecular Dynamics Simulation of Spontaneous Imbibition in Nanopores and Recovery of Asphaltenic Crude Oils Using Surfactants for EOR Applications Simulations de dynamique moléculaire d’imbibition spontanée dans des nanopores et pour la récupération d’huiles brutes asphalténiques en utilisant des agents tensioactifs pour des applications d’EOR

    Directory of Open Access Journals (Sweden)

    Stukan M.R.

    2012-12-01

    Full Text Available We present Molecular Dynamics (MD simulations of the imbibition process in nanopores in case of two different mechanisms of the wettability modification. We compare the imbibition of an aqueous surfactant solution into an oil-wet pore driven by surfactant adsorption onto the oil-wet rock surface (coating mechanism and the imbibition of an aqueous surfactants solution driven by surfactants removing the contaminant molecules from the originally water-wet surface (cleaning mechanism. Our results show qualitative difference in the imbibition dynamics in these two cases and indicate that MD simulation is a useful tool to investigate details of the imbibition mechanisms at the pore scale with direct implications for Enhanced Oil Recovery (EOR operations. Nous presentons des simulations de Dynamique Moleculaire (DM du processus d’imbibition dans des nanopores dans le cas de deux mecanismes differents de modification de mouillabilite. Nous comparons l’imbibition d’une solution aqueuse d’agent tensioactif dans un pore mouille d’huile entrainee par une adsorption d’agent tensioactif sur la surface de roche mouillee d’huile (mecanisme de revetement et l’imbibition d’une solution aqueuse d’agent tensioactif entrainee par des agents tensioactifs eliminant les molecules contaminantes de la surface originellement mouillee d’eau (mecanisme de nettoyage. Nos resultats montrent une difference qualitative en matiere de dynamique d’imbibition dans ces deux cas et indiquent que la simulation de DM constitue un outil utile pour etudier les mecanismes d’imbibition a l’echelle des pores avec des implications directes pour des operations de recuperation renforcee d’huile (EOR, Enhanced Oil Recovery.

  14. Caractérisation et simulation des mouvements d'atteinte par un opérateur humain en position assise en vue d'applications ergonomiques

    OpenAIRE

    CHEVALOT, N

    2006-01-01

    La simulation de mouvements d'atteinte effectués par un opérateur assis est particulièrement utile pour les constructeurs d'automobiles. Elle permet d'améliorer l'ergonomie de l'habitacle et des commandes, le plus en amont possible dans la conception. Elle consiste à simuler un mouvement et à prédire son inconfort. Cependant, ce type de simulation se heurte à des problèmes pratiques et théoriques. Pour la partie pratique, une méthode de simulation générique et stable pour tout type de mouveme...

  15. Comparative study on the stress corrosion cracking of X70 pipeline steel in simulated shallow and deep sea environments

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Feilong [Corrosion and Protection Center, University of Science and Technology Beijing, Beijing 100083 (China); Key Laboratory of Corrosion and Protection of Ministry of Education, Beijing 100083 (China); China Building Material Test & Certification Group Co. Ltd., Beijing 100024 (China); Ren, Shuai [Corrosion and Protection Center, University of Science and Technology Beijing, Beijing 100083 (China); Key Laboratory of Corrosion and Protection of Ministry of Education, Beijing 100083 (China); Li, Zhong [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada T6G 2G6 (Canada); Liu, Zhiyong, E-mail: liuzhiyong7804@ustb.edu.cn [Corrosion and Protection Center, University of Science and Technology Beijing, Beijing 100083 (China); Key Laboratory of Corrosion and Protection of Ministry of Education, Beijing 100083 (China); Li, Xiaogang; Du, Cuiwei [Corrosion and Protection Center, University of Science and Technology Beijing, Beijing 100083 (China); Key Laboratory of Corrosion and Protection of Ministry of Education, Beijing 100083 (China)

    2017-02-08

    The stress corrosion cracking (SCC) behavior of X70 steel in simulated shallow and deep sea environments was studied using potentiodynamic polarization measurement, a slow strain rate tensile (SSRT) test and scanning electron microscopy (SEM). The results indicate that the predominant cathodic reaction changes from an oxygen reduction reaction to the hydrogen evolution reaction as the dissolved oxygen (DO) content decreases. In the simulated deep sea environment, the SCC susceptibility of X70 steel decreased first, reached its lowest point at 15 MPa and then increased as the simulated sea hydrostatic pressure (HP) further increased. This is consistent with the regularity for the change of the cathodic hydrogen evolution reaction current density i{sub H} at E{sub corr}, which indicates that the HP may influence the SCC susceptibility of X70 steel by changing the permeated hydrogen concentration.

  16. Experimental study and simulation of cyclic softening of tempered martensite ferritic steels

    International Nuclear Information System (INIS)

    Giroux, P.-F.

    2011-01-01

    volume) linked to the various small obstacles present in the material (micro-precipitates, solid solution..). The value of the other parameters are either experimentally measured or deduced from computation results available in literature. The model correctly predicts the macroscopic softening behaviour and as well as the microstructural evolution during cycling. The parametrical study shows that the predictions are rather stable with respect to the variation of the physically-based parameter values. Predictions are improved by taking the initial subgrain size distribution and the initial dislocation density distribution into account. Finally, torsion tests are simulated and the presented model is used to predict the microstructural evolution of EUROFER 97 steel during cycling at room temperature. (author) [fr

  17. Une ressource pédagogique pour l'enseignement par simulation : cas des panneaux photovoltaïques

    OpenAIRE

    Motahhir , Saad; Ghzizal , Abdelaziz El; Sebti , Souad; Derouich , Aziz

    2015-01-01

    International audience; L'objectif de cet article est de présenter une approche pédagogique dédiée à l'enseignement des panneaux photovoltaïques (PV) aux différents niveaux d'études (lycée, bac+2, bac+3, bac+5), ça pour les écoles qui ont un problème de manque de matériels ou qui n'ont pas les moyens pour les acheter, ceci en utilisant des logiciels de prototypage et de modélisation/simulation à coût réduit (PSIM et MATLAB/SIMULINK), en plus cet article montre aussi comment utiliser ces logic...

  18. Modélisation, simulation et contrôle des installations cryogéniques du CERN

    CERN Document Server

    Bradu, Benjamin; Gayet, P

    2010-01-01

    Cette thèse présente le développement d'un simulateur de processus cryogéniques de grande taille appliqué aux installations cryogéniques de l'accélérateur de particules LHC (Large Hadron Collider) au CERN (Organisation Européenne pour la Recherche Nucléaire). Ce simulateur est basé sur une approche de modélisation orientée objet où chaque équipement (échangeur, turbine, compresseur, etc.) est représenté à partir d'un ensemble d'équations physiques algébro-différentielles. L'architecture de contrôle du CERN est également simulée en intégrant le contrôle réalisé par des automates programmables (PLC) avec le système de supervision. Ce simulateur à été développé pour servir différents desseins comme l'entraînement des opérateurs, la vérification des programmes automates (virtual commissioning) et l'optimisation des stratégies de contrôle. Le système cryogénique d'un détecteur de particules (CMS) a d'abord été simulé pour valider les modèles, puis un liquéfacteur d'...

  19. Volatility of ruthenium during vitrification operations on fission products. part 1. nitric solutions distillation concentrates calcination. part 2. fixation on a steel tube. decomposition of the peroxide; Volatilite du ruthenium au cours des operations de vitrification des produits de fission. 1. partie distillation des solutions nitriques calcination des concentrats 2. partie fixation sur un tube d'acier decomposition du peroxyde

    Energy Technology Data Exchange (ETDEWEB)

    Ortins de Bettencourt, A; Jouan, A [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1969-07-01

    During vitrification of fission product solutions, a high percentage of the ruthenium initially present in these solutions in the form of nitrosyl-ruthenium nitrates is volatilized with the production of the peroxide which itself is decomposed to ruthenium dioxide. The aim of this work has been to study the volatility of the ruthenium during the vitrification processes. During the distillation of the nitric solutions, we have studied in particular the influence on the volatility of the temperature , of the chemical form in which the ruthenium is introduced, of the bubbling of a gas through the solution, of the nitric concentration and of the nitrate concentration. During the calcination, we have observed the influence of the temperature, of the time, of the flow rate and of the nature of the carrier gas, as well as of the action of the ruthenium bi-oxide and the iron oxide on the volatility of the ruthenium. Part 2. This report deals with the study of the thermal decomposition of ruthenium peroxide, RuO{sub 4}, and its deposition on steel tubing. After a brief bibliographic review of the various properties of this substance, a study is made, in the first part, of its deposition on a steel tube. In order to do this, we pass a gas current containing RuO{sub 4} marked with {sup 106}Ru through a stainless steel tube subjected to a temperature gradient which decreases in the direction of the gas flow. The temperature at which RuO{sub 4} is deposited or is fixed on the tube is determined and the influence of the flow rate on this deposit is studied. In the second part, an attempt has been made to study by a static method the kinetics of the decomposition reaction of ruthenium peroxide to give the dioxide: RuO{sub 4} {yields} RuO{sub 2} + O{sub 2}. To do this, we have tried to introduce gaseous RuO{sub 4} into a container placed in an electric oven, and to follow the reaction by {gamma} counting. (author) [French] Au cours de la vitrification des solutions de produits de

  20. Volatility of ruthenium during vitrification operations on fission products. part 1. nitric solutions distillation concentrates calcination. part 2. fixation on a steel tube. decomposition of the peroxide; Volatilite du ruthenium au cours des operations de vitrification des produits de fission. 1. partie distillation des solutions nitriques calcination des concentrats 2. partie fixation sur un tube d'acier decomposition du peroxyde

    Energy Technology Data Exchange (ETDEWEB)

    Ortins de Bettencourt, A.; Jouan, A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1969-07-01

    During vitrification of fission product solutions, a high percentage of the ruthenium initially present in these solutions in the form of nitrosyl-ruthenium nitrates is volatilized with the production of the peroxide which itself is decomposed to ruthenium dioxide. The aim of this work has been to study the volatility of the ruthenium during the vitrification processes. During the distillation of the nitric solutions, we have studied in particular the influence on the volatility of the temperature , of the chemical form in which the ruthenium is introduced, of the bubbling of a gas through the solution, of the nitric concentration and of the nitrate concentration. During the calcination, we have observed the influence of the temperature, of the time, of the flow rate and of the nature of the carrier gas, as well as of the action of the ruthenium bi-oxide and the iron oxide on the volatility of the ruthenium. Part 2. This report deals with the study of the thermal decomposition of ruthenium peroxide, RuO{sub 4}, and its deposition on steel tubing. After a brief bibliographic review of the various properties of this substance, a study is made, in the first part, of its deposition on a steel tube. In order to do this, we pass a gas current containing RuO{sub 4} marked with {sup 106}Ru through a stainless steel tube subjected to a temperature gradient which decreases in the direction of the gas flow. The temperature at which RuO{sub 4} is deposited or is fixed on the tube is determined and the influence of the flow rate on this deposit is studied. In the second part, an attempt has been made to study by a static method the kinetics of the decomposition reaction of ruthenium peroxide to give the dioxide: RuO{sub 4} {yields} RuO{sub 2} + O{sub 2}. To do this, we have tried to introduce gaseous RuO{sub 4} into a container placed in an electric oven, and to follow the reaction by {gamma} counting. (author) [French] Au cours de la vitrification des solutions de produits de

  1. The resistance of austenitic stainless steels to pitting corrosion in simulated BFS/OPC pore waters containing thiosulphate ions

    International Nuclear Information System (INIS)

    Betts, A.J.; Newman, R.C.

    1989-06-01

    Current plans for the disposal of intermediate-level nuclear waste involve the use of austenitic stainless steel drums. The immediate environment seen by both the inner and outer surfaces of these drums will be alkaline, as a consequence of the encasement of both the drum and its contents in concrete. Normally there would be no risk of localized corrosion of the steel in this situation, but a possible complication is introduced by the use of blast-furnace slag (BFS) to decrease the permeability of the concrete. Metal sulphides in the BFS react with air and water to yield thiosulphate ions, which are known to be corrosive towards stainless steels in environments of near-neutral pH. This research was carried out to study the effects of thiosulphate at alkaline pH, simulating the concrete environment. Types 304L and 316L stainless steel have been tested for pitting corrosion resistance in simulated BFS/Ordinary Portland Cement pore waters of pH 10-13, at 20 o C and 50 o C. The results show that the 316L steel is essentially immune to pitting. The 304L steel shows some pitting at the higher temperature, especially at the higher chloride concentrations, but only at pH values of less than 12, which would require serious deterioration of the cement matrix. (author)

  2. Numerical simulation of spatial whole-body vibration behaviour of sitting man taking into account individual anthropometry and position; Numerische Simulation des raeumlichen Ganzkoerperschwingungsverhaltens des sitzenden Menschen unter Beruecksichtigung der individuellen Anthropometrie und Haltung

    Energy Technology Data Exchange (ETDEWEB)

    Pankoke, S.

    2003-07-01

    A dynamic FE model of the anatomy of humans in sitting position is presented for assessing the dynamic internal response of the human body to the effect of external vibrations. The model can be adapted to individual body measures, different positions and different spatial orientation. It was verified on the basis of extensive measured data. The problem of contact between the human body and the driver seat is solved by a simplified static description. The model comprises a sub-model of the lumbar vertebral column for assessing the spatial load distributions in this body region. [German] In der vorliegenden Arbeit wird ein dynamisches, an der menschlichen Anatomie orientiertes Finite-Elemente-Modell des sitzenden Menschen vorgestellt, das es gestaltet, dynamische innere Antworten des Koerpers auf von aussen auf den Menschen einwirkende Schwingungen zu ermitteln. Das Modell ist ueber eine Auswahl anthropometrischer Masse an das Schwingungsverhalten eines Individuums anpassbar und ermoeglicht zudem die Simulation von Schwingungseinwirkungen in unterschiedlichen Haltungen und in allen Raumrichtungen. Die Modellverifikation erfolgte an umfangreichen Messdatenbestaenden. Das Kontaktproblem des Menschen zum Fahrzeugsitz ist durch eine vereinfachte statische Beschreibung abgebildet. Ferner beinhaltet das Ganzkoerpermodell ein Submodell der Lendenwirbelsaeule, mit dessen Hilfe die aus den Ganzkoerperschwingungen folgenden raeumlichen Beanspruchungsverteilungen in der Lendenwirbelsaeule ermittelt werden koennen. (orig.)

  3. Computer simulation of the relationship between selected properties of laser remelted tool steel surface layer

    Energy Technology Data Exchange (ETDEWEB)

    Bonek, Mirosław, E-mail: miroslaw.bonek@polsl.pl; Śliwa, Agata; Mikuła, Jarosław

    2016-12-01

    Highlights: • Prediction of the properties of laser remelted surface layer with the use of FEM analysis. • The simulation was applied to determine the shape of molten pool of remelted surface. • Applying of numerical model MES for simulation of surface laser treatment to meaningfully shorten time of selection of optimum parameters. • An FEM model was established for the purpose of building a computer simulation. - Abstract: Investigations >The language in this paper has been slightly changed. Please check for clarity of thought, and that the meaning is still correct, and amend if necessary.include Finite Element Method simulation model of remelting of PMHSS6-5-3 high-speed steel surface layer using the high power diode laser (HPDL). The Finite Element Method computations were performed using ANSYS software. The scope of FEM simulation was determination of temperature distribution during laser alloying process at various process configurations regarding the laser beam power and method of powder deposition, as pre-coated past or surface with machined grooves. The Finite Element Method simulation was performed on five different 3-dimensional models. The model assumed nonlinear change of thermal conductivity, specific heat and density that were depended on temperature. The heating process was realized as heat flux corresponding to laser beam power of 1.4, 1.7 and 2.1 kW. Latent heat effects are considered during solidification. The molten pool is composed of the same material as the substrate and there is no chemical reaction. The absorptivity of laser energy was dependent on the simulated materials properties and their surface condition. The Finite Element Method simulation allows specifying the heat affected zone and the temperature distribution in the sample as a function of time and thus allows the estimation of the structural changes taking place during laser remelting process. The simulation was applied to determine the shape of molten pool and the

  4. Electrochemical corrosion of carbon steel exposed to biodiesel/simulated seawater mixture

    Energy Technology Data Exchange (ETDEWEB)

    Wang Wei [College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Department of Civil Engineering, University of Colorado Denver, Denver, CO 80217 (United States); Jenkins, Peter E. [Department of Mechanical Engineering, University of Colorado Denver, Denver, CO 80217 (United States); Ren Zhiyong, E-mail: zhiyong.ren@ucdenver.edu [Department of Civil Engineering, University of Colorado Denver, Denver, CO 80217 (United States)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Characterized the unique corrosion behaviour of carbon steel in the biodiesel/seawater environment. Black-Right-Pointing-Pointer Illustrated the in situ anode and cathode distribution using a wire beam electrode approach. Black-Right-Pointing-Pointer Elucidated the corrosion mechanisms based on ion transfer and oxygen concentration gradient. - Abstract: The electrochemical corrosion of carbon steel exposed to a mixture of biodiesel and 3.5% NaCl solution simulated seawater was characterized using wire beam electrode (WBE) technique. Both optical images and in situ potential and current measurements showed that all the anodes and most cathodes formed in the water phase, but the cathodes were mainly located along the water/biodiesel interface. Due to oxygen concentration gradient and cross-phase ion transfer, low corrosion currents were also detected in biodiesel phase. Further anode reaction was partially blocked by iron rust, but the alkali residual in biodiesel may interact with corrosion and deteriorate biodiesel quality.

  5. Contribution to the study of physico-chemical properties of surfaces modified by laser treatment. Application to the enhancement of localized corrosion resistance of stainless steels; Contribution a l'etude des proprietes physico-chimiques des surfaces modifiees par traitement laser. Application a l'amelioration de la resistance a la corrosion localisee des aciers inoxydables

    Energy Technology Data Exchange (ETDEWEB)

    Pacquentin, W.

    2011-11-25

    Metallic materials are more and more used in severe conditions with particularly strong request for improving their behavior in aggressive environment and especially over long periods. The objective of this PhD work is to estimate the potentiality of a laser surface melting treatment on the improvement of the stainless steel 304L corrosion resistance, surface treatments by laser can be revisited on the basis of a recent change in the laser technology. In the frame of this work, a nano-pulsed laser fiber was chosen: it allows the treated surface to be melted for few microns in depth, followed by an ultra-fast solidification occurring with cooling rates up to 1011 K/s. The combination of these processes leads to the elimination of the surface defects, the formation (trapping) of metastable phases, the segregation of chemical elements and the growth of a new oxide layer which properties are governed by the laser parameters. To correlate these latter to the electrochemical reactivity of the surface, the influence of two laser parameters on the physico-chemical properties of the surface was studied: the laser power and the overlap of the laser impacts. To support this approach, the pitting corrosion resistance of the samples was determined by standard electrochemical tests. For specific laser parameters, the pitting potential of a 304L stainless steel was increased by more than 500 mV corresponding to an important enhancement in localized corrosion resistance in chloride environment. The interdependence of the different phenomena resulting from the laser treatment lead to a quite complex prioritization of their role on the sensibility of the 304L. However, it was demonstrated that the nature of the thermal oxide formed during the laser surface melting and the induced defects are first-order parameters for the initiation of pits. (author) [French] Les materiaux metalliques sont utilises dans des conditions de plus en plus severes et doivent presenter une parfaite

  6. Stress corrosion cracking resistance of 22% Cr duplex stainless steel in simulated sour environments

    International Nuclear Information System (INIS)

    Kudo, T.; Tsuge, H.; Moroishi, T.

    1989-01-01

    This paper reports the effect of nickel and nitrogen contents on stress corrosion cracking (SCC) of 22%Cr - 3%Mo-base duplex stainless steel investigated in simulated sour environments with respect to both the base metal and the heat-affected zone (HAZ) of welding. The threshold stress and the critical chloride concentration for SCC were evaluated as a function of the ferrite content (α-content) in the alloy. The threshold stress is highest at the α-content of 40 to 45%, and is lowered with decreasing and increasing the α-content from its value. The alloy whose α-content exceeds 80% at the HAZ has also high susceptibilities to pitting corrosion and intergranular corrosion (ICG). The critical chloride concentration for cracking increases with the decrease in the α-content. Moreover, the contents of chromium, nickel and molybdenum in the α-phase are considered to be an important factor for determining the critical chloride concentration

  7. Numerical Simulation of Shear Slitting Process of Grain Oriented Silicon Steel using SPH Method

    Directory of Open Access Journals (Sweden)

    Bohdal Łukasz

    2017-12-01

    Full Text Available Mechanical cutting allows separating of sheet material at low cost and therefore remains the most popular way to produce laminations for electrical machines and transformers. However, recent investigations revealed the deteriorating effect of cutting on the magnetic properties of the material close to the cut edge. The deformations generate elastic stresses in zones adjacent to the area of plastically deformed and strongly affect the magnetic properties. The knowledge about residual stresses is necessary in designing the process. This paper presents the new apprach of modeling residual stresses induced in shear slitting of grain oriented electrical steel using mesh-free method. The applications of SPH (Smoothed Particle Hydrodynamics methodology to the simulation and analysis of 3D shear slitting process is presented. In experimental studies, an advanced vision-based technology based on digital image correlation (DIC for monitoring the cutting process is used.

  8. Numerical simulation of micro-crack occurring in pipe made of stainless steel

    Science.gov (United States)

    Wotzka, Daria

    2017-10-01

    Research works carried out regard to studies aiming at determination of the effect of cumulative duty operation on the development of micro-cracks in pipelines for transport of chemical substances. This paper presents results of computer simulations of a pipeline made of stainless steel. The model was investigated using the COMSOL Multiphysics environment. The object under study was divided into sub areas and then discretized according to the FEM method. The physico-chemical parameters of individual areas were defined based on measurement data. The main aim of research works was the modeling of acoustic emission wave, which is emitted in the vicinity of the tip of micro-crack as a result of its development. In order to solve the task, heterogeneity in the structure of the material, referred to damage/micro-crack, causing local stresses was assumed. The local stresses give rise to elastic waves, which propagate in the material in all directions. When the emission waves reach the boundaries of the pipe they are then transferred into acoustic waves and propagate in the surround air, until their natural attenuation. The numerical model takes into account the effect of high pressure (3.6 MPa) and negative temperature (-100°C) of the gas, transported inside the pipe. The influence of changes of these values in the range of ± 20% on the obtained results was investigated. The main contribution of the works is the multiphysical simulation model of transportation pipe made of steel, coupling structural mechanics, thermal conductivity and acoustic waves.

  9. Numerical simulation of micro-crack occurring in pipe made of stainless steel

    Directory of Open Access Journals (Sweden)

    Wotzka Daria

    2017-01-01

    Full Text Available Research works carried out regard to studies aiming at determination of the effect of cumulative duty operation on the development of micro-cracks in pipelines for transport of chemical substances. This paper presents results of computer simulations of a pipeline made of stainless steel. The model was investigated using the COMSOL Multiphysics environment. The object under study was divided into sub areas and then discretized according to the FEM method. The physico-chemical parameters of individual areas were defined based on measurement data. The main aim of research works was the modeling of acoustic emission wave, which is emitted in the vicinity of the tip of micro-crack as a result of its development. In order to solve the task, heterogeneity in the structure of the material, referred to damage/micro-crack, causing local stresses was assumed. The local stresses give rise to elastic waves, which propagate in the material in all directions. When the emission waves reach the boundaries of the pipe they are then transferred into acoustic waves and propagate in the surround air, until their natural attenuation. The numerical model takes into account the effect of high pressure (3.6 MPa and negative temperature (-100̊C of the gas, transported inside the pipe. The influence of changes of these values in the range of ± 20% on the obtained results was investigated. The main contribution of the works is the multiphysical simulation model of transportation pipe made of steel, coupling structural mechanics, thermal conductivity and acoustic waves.

  10. Computer simulation of the influence of the alloying elements on secondary hardness of the high-speed steels

    International Nuclear Information System (INIS)

    Dobrzanski, L.A.; Sitek, W.; Zaclona, J.

    2004-01-01

    The paper presents the method of modelling of high-speed steels' (HSS) properties, being basing on chemical composition and heat treatment parameters, employing neural networks. An example of its application possibility the computer simulation was made of the influence of the particular alloying elements on hardness and obtained results are presented. (author)

  11. Solution des systemes de controle de grandes dimensions basee sur les boucles de retroaction dans la simulation des reseaux electriques

    Science.gov (United States)

    Mugombozi, Chuma Francis

    The generation of electrical energy, as well as its transportation and consumption, requires complex control systems for the regulation of power and frequency. These control systems must take into account, among others, new energy sources such as wind energy and new technologies for interconnection by high voltage DC link. These control systems must be able to monitor and achieve such regulation in accordance with the dynamics of the energy source, faults and other events which may induce transients phenomena into the power network. Such transients conditions have to be analyzed using the most accurate and detailed hence, complex models of control system. In addition, in the feasibility study phase, the calibration or the setup of equipment as well as in the operation of the power network, one may require decision aid tools for engineers. This includes, for instance, knowledge of energy dissipated into the arresters in transient analysis. These tools use simulation programs data as inputs and may require that complex functions be solved with numerical methods. These functions are part of control system in computer simulator. Moreover, the simulation evolves in a broader context of the development of digital controller, distributed and parallel high performance computing and rapid evolutions in computer (multiprocessor) technology. In such context, a continuing improvement of the control equations solver is welcomed. Control systems are modelled using ax=b simultaneous system of equations. These equations are sometimes non-linear with feedback loops and thus require iterative Newton methods, including the formation of a Jacobian matrix and ordering as well as processing by graph theory tools. The proposed approach is based on the formulation of a reduced rank Jacobian matrix. The dimension is reduced up to the count of feedback loops. With this new approach, gains in computation speed are expected without compromising its accuracy when compared to classical full

  12. Hydroforming simulation and preparation of low activation martensitic steel Y-shapes

    International Nuclear Information System (INIS)

    Guo, X.Z.; Tao, J.; Yuan, Z.; Tang, Q.S.

    2011-01-01

    Highlights: → We hydroformed CLAM Y-shapes successfully after optimizing important parameters. → The feed of left punch decreased with the increasing protrusion angle. → The axial feed of the right punch increased with increasing the angle. → To obtain the highest protrusion, loading path 3 was the optimum. → The friction coefficient value of 0.07 is relatively superior. - Abstract: The hydroforming process to prepare China low activation Martensitic steel (CLAM) Y-shapes with desired protrusion height and uniform thinning rate was studied in this work. The axial feed distances for Y-shapes of the different protrusion angles were determined. Then, the effects of the loading path and the friction coefficient on the protrusion height and the distribution of thinning rate of the 45 o Y-shapes were investigated by numerical simulation, respectively. The optimized parameters were obtained: left axial feed 79 mm, right axial feed 60 mm and friction coefficient 0.07. In addition, the optimal loading path with the maximum rise rate of the internal pressure was determined. Subsequently, CLAM Y-shapes were hydroformed successfully based on the simulation results. The experimental results were approximately accordant with the simulative ones. It was indicated that the qualified CLAM Y-shapes could be obtained by the optimized hydroforming process.

  13. Numerical simulation of flow and heat transfer of continous cast steel slab under traveling magnetic field

    Directory of Open Access Journals (Sweden)

    Gong Haijun

    2013-03-01

    Full Text Available A unified numerical model for simulating solidification transport phenomena (STP of steel slab in electromagnetic continuous casting (EMCC process was developed. In order to solve the multi-physics fields coupled problem conveniently, the complicated bidirectional coupled process between EM and STP was simplified as a unidirectional one, and a FEM/FVM-combined numerical simulation technique was adopted. The traveling magnetic fields (TMFs applied to the EMCC process were calculated using the ANSYS11.0 software, and then the EM-data output by ANSYS were converted to FVM-format using a data-format conversion program developed previously. Thereafter, the governing equations were solved using a pressure-based Direct-SIMPLE algorithm. The simulation results of the STP in CC-process show that, due to the influences of Lorentz force and Joule heat, the two strong circulating flows and the temperature field can be obviously damped and changed once TMF with one pair of poles (1-POPs or 2-POPs is applied, which would accordingly improve the quality of casting. It was found in the present research that the integrated actions of 2-POPs TMF are superior to 1-POPs. All the computations indicate that the present numerical model of EM-STP as well as the FEM/FVM-combined technique is successful.

  14. Numerical Simulation of Galvanic Corrosion Caused by Shaft Grounding Systems in Steel Ship Hulls

    National Research Council Canada - National Science Library

    Wang, Y

    2005-01-01

    .... This led to the accelerated corrosion of the exposed steel ship hull on paint holidays because of the substantial difference of the electric potentials between the steel ship hull and the nickel...

  15. Numerical simulation of hydrogen-assisted crack initiation in austenitic-ferritic duplex steels; Numerische Simulation der wasserstoffunterstuetzten Rissbildung in austentisch-ferritischen Duplexstaehlen

    Energy Technology Data Exchange (ETDEWEB)

    Mente, Tobias

    2015-07-01

    Duplex stainless steels have been used for a long time in the offshore industry, since they have higher strength than conventional austenitic stainless steels and they exhibit a better ductility as well as an improved corrosion resistance in harsh environments compared to ferritic stainless steels. However, despite these good properties the literature shows some failure cases of duplex stainless steels in which hydrogen plays a crucial role for the cause of the damage. Numerical simulations can give a significant contribution in clarifying the damage mechanisms. Because they help to interpret experimental results as well as help to transfer results from laboratory tests to component tests and vice versa. So far, most numerical simulations of hydrogen-assisted material damage in duplex stainless steels were performed at the macroscopic scale. However, duplex stainless steels consist of approximately equal portions of austenite and δ-ferrite. Both phases have different mechanical properties as well as hydrogen transport properties. Thus, the sensitivity for hydrogen-assisted damage is different in both phases, too. Therefore, the objective of this research was to develop a numerical model of a duplex stainless steel microstructure enabling simulation of hydrogen transport, mechanical stresses and strains as well as crack initiation and propagation in both phases. Additionally, modern X-ray diffraction experiments were used in order to evaluate the influence of hydrogen on the phase specific mechanical properties. For the numerical simulation of the hydrogen transport it was shown, that hydrogen diffusion strongly depends on the alignment of austenite and δ-ferrite in the duplex stainless steel microstructure. Also, it was proven that the hydrogen transport is mainly realized by the ferritic phase and hydrogen is trapped in the austenitic phase. The numerical analysis of phase specific mechanical stresses and strains revealed that if the duplex stainless steel is

  16. Experiments and FE-simulations of stretch flanging of DP-steels with different shear cut edge quality

    Science.gov (United States)

    Sigvant, M.; Falk, J.; Pilthammar, J.

    2017-09-01

    Dual-Phase (DP) steels are today used in the automotive industry due to its large strength to weight ratio. However, the high strength of DP-steel does have a negative impact on the general formability in sheet metal forming. Unfavourable process conditions in the press shop will, on top of this, reduce the formability of DP-steels even more. This paper addresses the problem of edge fracture in stretch flanges in sheet metal parts made of DP-steel. The experimental part involves tests of ten different DP590 and DP780 steel grades with three different shear cut qualities. The influence on the fracture strain of the sample orientation of the shear cut are also studied by facing the burr away or towards the punch and testing samples with the cut edge parallel with the rolling direction and the transverse direction. The strains are measured with an ARAMIS system in each test, together with punch displacement and punch force. All tests are then simulated with AutoFormplus R7 and the results from these simulations are compared with the experimental results in order to find the appropriate failure strain for each combination of supplier, coating, thickness and shear cut quality.

  17. Modelling of the ultrasonic inspection of steel tubes with longitudinal defects; Modelisation du controle ultrasonore de tubes d`acier presentant des defauts de type ``entaille longitudinale``

    Energy Technology Data Exchange (ETDEWEB)

    Mephane, M

    1998-12-31

    A model has been developed in order to simulate the ultrasonic inspection of steel tubes in the Vallourec control configuration. The model permits to simulate the control of steel tubes showing longitudinal defects located near the internal or external surface of tubes which appear during the rolling process. To detect this kind of defect, the probe is placed in an incident place perpendicular to the tube`s axis. The probe is in front of the external surface of the tube. The main characteristics of the model is to assume that the field radiated in the material does not depend on the probe`s position. This assumption permits to treat separately the field retracted in the material and the interaction between the defect and the ultrasonic beam. The focal plane is located in the material, so the plane waves approximation is applied where the waves front are assumed plane and parallel. The parallel refracted beam becomes divergent after reflection on the internal surface of tube. To treat the beam divergence, an amplitude weighting coefficient is then calculated by mean of the energy conservation of a tube of rays before and after reflection, following the Snell laws. This model can predict the edge diffraction echoes, the echoes issued from the corner effect, and also the mode conversion echoes. It has been validated on artificial notches, and on some natural defects. A comparison between experimental and modelling results shows a good agreement. (author) 39 refs.

  18. Comparison of Austenite Decomposition Models During Finite Element Simulation of Water Quenching and Air Cooling of AISI 4140 Steel

    Science.gov (United States)

    Babu, K.; Prasanna Kumar, T. S.

    2014-08-01

    An indigenous, non-linear, and coupled finite element (FE) program has been developed to predict the temperature field and phase evolution during heat treatment of steels. The diffusional transformations during continuous cooling of steels were modeled using Johnson-Mehl-Avrami-Komogorov equation, and the non-diffusion transformation was modeled using Koistinen-Marburger equation. Cylindrical quench probes made of AISI 4140 steel of 20-mm diameter and 50-mm long were heated to 1123 K (850 °C), quenched in water, and cooled in air. The temperature history during continuous cooling was recorded at the selected interior locations of the quench probes. The probes were then sectioned at the mid plane and resultant microstructures were observed. The process of water quenching and air cooling of AISI 4140 steel probes was simulated with the heat flux boundary condition in the FE program. The heat flux for air cooling process was calculated through the inverse heat conduction method using the cooling curve measured during air cooling of a stainless steel 304L probe as an input. The heat flux for the water quenching process was calculated from a surface heat flux model proposed for quenching simulations. The isothermal transformation start and finish times of different phases were taken from the published TTT data and were also calculated using Kirkaldy model and Li model and used in the FE program. The simulated cooling curves and phases using the published TTT data had a good agreement with the experimentally measured values. The computation results revealed that the use of published TTT data was more reliable in predicting the phase transformation during heat treatment of low alloy steels than the use of the Kirkaldy or Li model.

  19. Simulation numérique des transferts thermiques dans un système de séchage solaire du bois

    OpenAIRE

    Khouya , Ahmed; Benabdelouhab , Jaâfar; Draoui , Abdeslam

    2007-01-01

    International audience; Les auteurs présentent une étude théorique sur un système de séchage constitué d'un capteur solaire à air de type multi–passes muni d'ailettes et couplé à une cuve de stockage dans les conditions climatiques de la région de Tanger au Maroc. L'étude est réalisée à partir des modèles mathématiques obtenus par l'écriture des lois de conservation de l'énergie dans les différentes composantes du système. Des simulations ont été réalisées en exploitant des mesures expériment...

  20. Experiment and numerical simulation of welding induced damage: stainless steel 15-5PH

    International Nuclear Information System (INIS)

    Wu, T.

    2007-11-01

    The objective of this study is the prediction of damage and residual stresses induced by hot processing which leads to phase transformation in martensitic stainless steel. This study firstly concerns the modelling of the damage of material induced by a complex history of thermo-elastoplastic multiphase in heat-affected-zone (HAZ) of welding. In this work, a two-scale mode of elastoplastic damage multiphase was developed in the framework of thermodynamics of irreversible process. The constitutive equations are coupling with ductile damage, elasto-plasticity, phase transformation, and transformation plasticity. Besides, a damage equation was proposed based on the Lemaitre's damage model in the framework of continuum damage mechanics. The experiments of 15-5PH were implemented for the identification of phase transformation, transformation plasticity and damage models. Tensile tests of round specimens were used to identify the parameters of damage model as well as mechanical behaviours at various temperatures. Tests of flat notched specimen were designed to provide the validation of damage model and strain localization using three dimensional image correlation technologies. In addition, microscopic analysis was performed to provide microstructure characterization of 15-5PH and to discover the damage mechanism. Finally the numerical simulation was performed in the code CAST3M of CEA. On the one hand, numerical verification of the flat notched plates was implemented and compared with experimental results. On the other hand, we used the two-scale model including phase transformation, transformation plasticity and damage to simulate the level of residual stresses of a disk made of 15-5PH metal heated by laser. The internal variables, such as strain, stress, damage, were successfully traced in the simulation of two-scale model. The simulation results showed the transformation plasticity changes the level of residual stresses and should not be negligible; damage decreases

  1. Weldability examination of ASTM A 240 S41500 martensitic stainless steel by thermal cycles simulation testings

    Directory of Open Access Journals (Sweden)

    Alberto Velázquez-del Rosario

    2015-07-01

    Full Text Available The weldability assets of ASTM A 240 S41500 (ASTM A 240/A 240M martensitic stainless steel are presented through the study of the effects of single and double thermal weld cycles on mechanical properties and microstructure of base metal (BM and the artificial heat affected zone (HAZ created by thermal weld simulations. For single cycles, separate peak temperatures of 1000 ºC/12 s and 1350 ºC/12 s (cooling times: 12 s in both cases were evaluated, whilst two combinations of peak temperatures: (1350 ºC/5 s + 1000 ºC/5 s ºC and (1350 ºC/12 s + 1000 ºC/12 s ºC (cooling times: 5 s and 12 s, were applied for double cycles. Post weld heat treatment (PWHT with short and long holding times were applied and Vickers hardness, impact toughness and metallographic examinations were used in order to assess mechanical and metallographic properties in the as-simulated (no heat treated and postweld heat treated conditions. Best properties of the welded joint for double thermal weld cycles with long holding times were reached, which reveals the good weldability and applicability of the tested material in post weld heat treated conditions.

  2. Numerical simulation of the hole-flanging process for steel-polymer sandwich sheets

    Science.gov (United States)

    Griesel, Dominic; Keller, Marco C.; Groche, Peter

    2018-05-01

    In light of increasing demand for lightweight structures, hybrid materials are frequently used in load-optimized parts. Sandwich structures like metal-polymer sandwich sheets provide equal bending stiffness as their monolithic counterparts at a drastically reduced weight. In addition, sandwich sheets have noise-damping properties, thus they are well-suited for a large variety of parts, e.g. façade and car body panels, but also load-carrying components. However, due to the creep tendency and low heat resistance of the polymer cores, conventional joining technologies are only applicable to a limited degree. Through hole-flanging it is possible to create branches in sandwich sheets to be used as reinforced joints. While it is state of the art for monolithic materials, hole-flanging of sandwich sheets has not been investigated yet. In order to simulate this process for different material combinations and tool geometries, an axisymmetric model has been developed in the FE software Abaqus/CAE. In the present paper, various modeling strategies for steel-polymer sandwich sheets are examined, including volume elements, shell elements and combinations thereof. Different methods for joining the distinct layers in the FE model are discussed. By comparison with CT scans and optical 3D measurements of experimentally produced hole-flanges, the feasibility of the presented models is evaluated. Although a good agreement of the numerical and experimental results has been achieved, it becomes clear that the classical forming limit diagram (FLD) does not adequately predict failure of the steel skins.

  3. Fatigue crack growth threshold of austenitic stainless steels in simulated PWR primary water

    International Nuclear Information System (INIS)

    Tsutsumi, Kazuya; Yamamoto, Kenji; Nitta, Yoshikazu

    2007-01-01

    Many studies have revealed that fatigue crack growth (FCG) rate of austenitic stainless steels is accelerated in light water reactor environment compared to that in air at room temperature. Major driving factors in the acceleration of FCG rate are stress ratio, temperature and stress rise time. Based on this knowledge, FCG curves have been developed considering these factors as parameters. However, there are few data of FCG threshold ΔK th in light water reactor environment. Hence it is necessary to clarify FCG rate under near-threshold condition for more accurate evaluation of fatigue crack growth behavior under cyclic stress with relatively low ΔK. In the present study, therefore, ΔK th was determined for austenitic stainless steels in simulated PWR primary water, and FCG behavior under near-threshold condition was revealed by collecting fatigue crack propagation data. The results are summarized as follows: No propagation of fatigue crack was found in high temperature water, and there was a definite ΔK th . Average ΔK eff,th was 4.3 MPa·m 0.5 at 325degC, 3.3 MPa·m 0.5 at 100degC, and there was no considerable reduction compared to currently known ΔK eff,th in air. Thus, it was revealed tha ambient conditions had minimal effect, on ΔK eff,th , ΔK th increases with increasing temperature and decreasing frequency. As a result of fracture surface observation, oxide-induced-crack-closure was considered to be a cause of the dependency described above. In addition, it was suggested that changes in material properties also had influence on ΔK th, since ΔK eff,th itself increased at elevated temperature. (author)

  4. Steam explosion triggering phenomena: stainless steel and corium-E simulants studied with a floodable arc melting apparatus

    International Nuclear Information System (INIS)

    Nelson, L.S.; Buxton, L.D.

    1978-05-01

    Laboratory-scale experiments on the thermal interaction of light water reactor core materials with water have been performed. Samples (10--35 g) of Type 304 stainless steel and Corium-E simulants were each flooded with approximately 1.5 litres of water to determine whether steam explosions would occur naturally. Many of the experiments also employed artificially induced pressure transients in an attempt to initiate steam explosions. Vigorous interactions were not observed when the triggering pulse was not applied, and for stainless steel the triggering pulse initiated only coarse fragmentation. Two-stage, pressure-producing interactions were triggered for an ''oxidic'' Corium-E simulant. An impulse-initiated gas release theory has been simulated to explain the initial sample fragmentation. Although the delayed second stage of the event is not fully understood, it does not appear to be readily explained with classical vapor explosion theory. Rather, some form of metastability of the melt seems to be involved

  5. A case study of environmental assisted cracking in a low alloy steel under simulated environment of pressurized water reactor

    International Nuclear Information System (INIS)

    Shahzad, M.; Qureshi, A.H.; Waqas, H.; Hussain, N.

    2011-01-01

    Highlights: → We study environmental assisted cracking (EAC) in simulated PWR environment. → The corrosion rate in simulated coolant is low but increases with B conc. → A516 steel shows EAC in simulated coolant particularly at high oxygen levels. → Fracture occurs when the surface cracks join the subsurface cracks. → Corrosion of MnS inclusions and ferrite provide crack nucleation sites. -- Abstract: The electromechanical behavior of a pressure vessel grade steel A516 has been investigated using potentiodynamic polarization curves and slow strain rate test (SSRT) in simulated environment of pressurized water reactor. The anodic polarization behavior shows that the steel remains active in the solution till localized attack (pitting) starts. The cracks initiated at the surface propagate in a trans-granular mode. These cracks are initiated at the inclusion (MnS) sites and at the interfaces between local anode (ferrite) and local cathode (pearlite). It seems that the ultimate fracture occurs when the propagating surface cracks join the subsurface hydrogen induced cracks. The addition of oxygen in the testing chamber to supersaturation levels shifts the corrosion potential to anodic side and significantly lowers the strength and ductility. Compared to the room temperature properties, the UTS and tensile elongation in various simulated conditions are reduced by 10-25% and 25-75%, respectively.

  6. In-Pile Tests for IASCC Growth Behavior of Irradiated 316L Stainless Steel under Simulated BWR Condition in JMTR

    Science.gov (United States)

    Chimi, Yasuhiro; Kasahara, Shigeki; Ise, Hideo; Kawaguchi, Yoshihiko; Nakano, Junichi; Nishiyama, Yutaka

    The Japan Atomic Energy Agency (JAEA) has an in-pile irradiation test plan to evaluate in-situ effects of neutron/γ-ray irradiation on stress corrosion crack (SCC) growth of irradiated stainless steels using the Japan Materials Testing Reactor (JMTR). SCC growth rate and its dependence on electrochemical corrosion potential (ECP) are different between in-pile test and post irradiation examination (PIE). These differences are not fully understood because of a lack of in-pile data. This paper presents a systematic review on SCC growth data of irradiated stainless steels, an in-pile test plan for crack growth of irradiated SUS316L stainless steel under simulated BWR conditions in the JMTR, and the development of the in-pile test techniques.

  7. Design of steel lined pressure tunnels and shafts - Annual report; Dimensionnement des galeries et puits blindes - Rapport annuel

    Energy Technology Data Exchange (ETDEWEB)

    Hachem, F.; Schleiss, A.

    2009-07-01

    Modern power plants are expected to operate at variable speed in a wide range of output power with improved efficiency, flexibility and safety. Therefore, the pumped-storage power generation has gained in importance since it allows storing and generating electricity to supply high peak demands by moving water back and forth between reservoirs at different elevations. A project consortium, called HydroNet (Modern Methodologies for Design, Manufacturing and Operation of Pumped-Storage Power Plant) has been created aiming to converge towards a consistent standardized methodology for design, manufacturing, operation, monitoring and control of pumped-storage power plants in order to give new impulsions in the hydropower technology and maintain the strong position of Switzerland in peak hydropower production as well as in the exportation of high-valued technology. One of the civil engineering field involved in this consortium is the design and control of pressurized shafts and tunnels with a special focus on safety. Since 1980s, no significant fundamental research has been performed aiming to integrate design with interaction between water, steel lining and rock mass. The results of these investigations stand for a crucial target in Switzerland since the collapse of the shallow buried pressure shaft of Cleuson-Dixence hydropower plant in December 2000. (authors)

  8. Analysis of corrosion data for carbon steels in simulated salt repository brines and acid chloride solutions at high temperatures

    International Nuclear Information System (INIS)

    Diercks, D.R.; Hull, A.B.; Kassner, T.F.

    1988-03-01

    Carbon steel is currently the leading candidate material for fabrication of a container for isolation of high level nuclear waste in a salt repository. Since brine entrapped in the bedded salt can migrate to the container by several transport processes, corrosion is an important consideration in the long-term performance of the waste package. A detailed literature search was performed to compile relevant corrosion data for carbon steels in anoxic acid chloride solutions, and simulated salt repository brines at temperatures between ∼ 20 and 400 0 C. The hydrolysis of Mg 2+ ions in simulated repository brines containing high magnesium concentrations causes acidification at temperatures above 25 0 C, which, in turn, influences the protective nature of the magnetite corrosion product layer on carbon steel. The corrosion data for the steels were analyzed, and an analytical model for general corrosion was developed to calculate the amount of penetration (i.e., wall thinning) as a function of time, temperature, and the pressure of corrosion product hydrogen than can build up during exposure in a closed system (e.g., a sealed capsule). Both the temperature and pressure dependence of the corrosion rate of steels in anoxic acid chloride solutions indicate that the rate-controlling partial reaction is the cathodic reduction of water to form hydrogen. Variations in the composition and microstructure of the steels or the concentration of the ionic species in the chloride solutions (provided that they do not change the pH significantly) do not appear to strongly influence the corrosion rate

  9. Deep Drawing Simulation Of High And Ultrahigh Strength Steels Under Consideration Of Anisotropic Hardening

    International Nuclear Information System (INIS)

    Roll, Karl; Faust, Alexander; Kessler, Lutz

    2007-01-01

    In today's sheet metal forming simulation, most attention is paid to yield loci functions, which describe the anisotropy of the material in yielding. The coefficients, defining the shape of the yield locus in these functions are usually fitted at a certain level of plastic work and are then valid for the whole range of plastic deformation. Modern high and ultrahigh strength steels, especially those with induced plasticity, may often exhibit only a very small anisotropy in yielding, but a severe anisotropy in work hardening for different loading conditions. This behavior can not be described by fitting the yield locus at a specific value of plastic deformation. An approach to take into account the anisotropic hardening of sheet metals is to provide different yield curves for several loading conditions and expand the yield locus dependent on the current form of load. By doing this, one can use a comparatively simple yield locus, like that of Hill from 1948, because all anisotropy is given by the different hardening curves. For the commercial FEM code LS DYNA the material model MATFEM Generalized Yield is available as a user subroutine, which supports this approach. In this paper, forming simulation results of different yield loci are compared with experimental results. The simulations were carried out in LS-DYNA with the Barlat 89 and 2000 yield loci and isotropic hardening and with the GenYld model combining a Hill 48 yield locus and anisotropic hardening. The deep drawing experiments were conducted on a hydraulic press, measuring binder and punch forces. The deformation of the sheet was measured by optical grid analysis. A comparison of the simulated and measured plastic strains shows that using a model including anisotropic hardening can produce better results than the usage of a complex yield locus but isotropic hardening for the examined materials. This might be interesting for e.g. spring back simulations. By combining a simple yield locus with anisotropic

  10. The Investigation on Flexural Toughness of Partially Steel Fiber Reinforced Concrete Immersed by Simulated Sea-Water

    Directory of Open Access Journals (Sweden)

    Feng GAO

    2017-11-01

    Full Text Available In order to investigate the corrosive resistance of partially steel fiber reinforced concrete (PSFRC, the flexural toughness experiment of nine specimens subjected to corrosion by alternating wet and dry cycles in a simulated marine environment were conducted, which aims at investigating the effect of corrosion time, steel fiber volume fraction and SFRC thickness on PSFRC toughness. The experimental results showed that both the mechanical and ductile characteristics of PSFRC got worse due to corrosion even if increasing the steel fiber volume. Additionally, the effect of steel fiber content on the toughness and ultimate load are greater than PSFRC thickness (t. The increase of 56.6% and 171% could be obtained in the mean ultimate load and I10 if the increase of steel fiber volume is from 0.5 % to 2.0%, respectively. This paper could offer a reference to the application of PSFRC in sea-water environment.DOI: http://dx.doi.org/10.5755/j01.ms.23.4.17049

  11. LOCAL COLLISION SIMULATION OF AN SC WALL USING ENERGY ABSORBING STEEL

    Directory of Open Access Journals (Sweden)

    CHUL-HUN CHUNG

    2013-08-01

    Full Text Available This study evaluates the local damage of a turbine in an auxiliary building of a nuclear power plant due to an external impact by using the LS-DYNA finite element program. The wall of the auxiliary building is SC structure and the material of the SC wall plate is high manganese steel, which has superior ductility and energy absorbance compared to the ordinary steel used for other SC wall plates. The effects of the material of the wall, collision speed, and angle on the magnitude of the local damage were evaluated by local collision analysis. The analysis revealed that the SC wall made of manganese steel had significantly less damage than the SC wall made of ordinary steel. In conclusion, an SC wall made of manganese steel can have higher effective resistance than an SC wall made of ordinary steel against the local collision of an airplane engine or against a turbine impact.

  12. Local Collision Simulation of an SC Wall Using Energy Absorbing Steel

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chulhun; Choi, Hyun; Park, Jaegyun [Dankook Univ., Yongin (Korea, Republic of)

    2013-08-15

    This study evaluates the local damage of a turbine in an auxiliary building of a nuclear power plant due to an external impact by using the LS-DYNA finite element program. The wall of the auxiliary building is SC structure and the material of the SC wall plate is high manganese steel, which has superior ductility and energy absorbance compared to the ordinary steel used for other SC wall plates. The effects of the material of the wall, collision speed, and angle on the magnitude of the local damage were evaluated by local collision analysis. The analysis revealed that the SC wall made of manganese steel had significantly less damage than the SC wall made of ordinary steel. In conclusion, an SC wall made of manganese steel can have higher effective resistance than an SC wall made of ordinary steel against the local collision of an airplane engine or against a turbine impact.

  13. Study of structural modifications induced by ion implantation in austenitic stainless steel; Etude des modifications structurales induites par implantation ionique dans les aciers austenitiques

    Energy Technology Data Exchange (ETDEWEB)

    Dudognon, J

    2006-12-15

    Ion implantation in steels, although largely used to improve the properties of use, involves structural modifications of the surface layer, which remain still prone to controversies. Within this context, various elements (N, Ar, Cr, Mo, Ag, Xe and Pb) were implanted (with energies varying from 28 to 280 keV) in a 316LVM austenitic stainless steel. The implanted layer has a thickness limited to 80 nm and a maximum implanted element concentration lower than 10 % at. The analysis of the implanted layer by grazing incidence X ray diffraction highlights deformations of austenite lines, appearance of ferrite and amorphization of the layer. Ferritic phase which appears at the grain boundaries, whatever the implanted element, is formed above a given 'threshold' of energy (produced of fluency by the energy of an ion). The formation of ferrite as well as the amorphization of the implanted layer depends only on energy. In order to understand the deformations of austenite diffraction lines, a simulation model of these lines was elaborated. The model correctly describes the observed deformations (broadening, shift, splitting) with the assumption that the expansion of the austenitic lattice is due to the presence of implanted element and is proportional to the element concentration through a coefficient k'. This coefficient only depends on the element and varies linearly with its radius. (author)

  14. Towards Eulerian-Eulerian large eddy simulation of reactive two-phase plows; Vers la simulation des grandes echelles en formulation Euler-Euler des ecoulements reactifs diphasiques

    Energy Technology Data Exchange (ETDEWEB)

    Kaufmann, A.

    2004-03-15

    Particle laden flows occur in industrial applications ranging from droplets in gas turbines to fluidized bed in chemical industry. Prediction of the dispersed phase properties such as concentration and dynamics are crucial for the design of more efficient devices that meet the new pollutant regulations of the European community. Numerical simulation coupling Lagrangian tracking of discrete particles with DNS or LES of the carrier phase provide a well established powerful tool to investigate particle laden flows. Such numerical methods have the drawback of being numerically very expensive for practical applications. Numerical simulations based on separate Eulerian balance equations for both phases, coupled through inter-phase exchange terms might be an effective alternative approach. This approach has been validated for the case of tracer particles with very low inertia that follow the carrier phase almost instantaneously due to their small response time compared with the micro-scale time scales of the carrier phase. Objective of this thesis is to extend this approach to more inertial particles that occur in practical applications such as fuel droplets in gas turbine combustors. Existing results suggest a separation of the dispersed phase velocity into a correlated and an uncorrelated component. The energy related to the uncorrelated component is about 30% of the total particle kinetic energy when the particle relaxation time is comparable to the Lagrangian integral time scale. The presence of this uncorrelated motion leads to stress terms in the Eulerian balance equation for the particle momentum. Models for this stress terms are proposed and tested. Numerical simulations in the Eulerian framework are validated by comparison with simulations using Lagrangian particle tracking. Additionally coupling of the Eulerian transport equations for the particles to combustion models is tested. (author)

  15. Electrochemical characterization of AISI 316L stainless steel in contact with simulated body fluid under infection conditions.

    Science.gov (United States)

    López, Danián Alejandro; Durán, Alicia; Ceré, Silvia Marcela

    2008-05-01

    Titanium and cobalt alloys, as well as some stainless steels, are among the most frequently used materials in orthopaedic surgery. In industrialized countries, stainless steel devices are used only for temporary implants due to their lower corrosion resistance in physiologic media when compared to other alloys. However, due to economical reasons, the use of stainless steel alloys for permanent implants is very common in developing countries. The implantation of foreign bodies is sometimes necessary in the modern medical practice. However, the complex interactions between the host and the can implant weaken the local immune system, increasing the risk of infections. Therefore, it is necessary to further study these materials as well as the characteristics of the superficial film formed in physiologic media in infection conditions in order to control their potential toxicity due to the release of metallic ions in the human body. This work presents a study of the superficial composition and the corrosion resistance of AISI 316L stainless steel and the influence of its main alloying elements when they are exposed to an acidic solution that simulates the change of pH that occurs when an infection develops. Aerated simulated body fluid (SBF) was employed as working solution at 37 degrees C. The pH was adjusted to 7.25 and 4 in order to reproduce normal body and disease state respectively. Corrosion resistance was measured by means of electrochemical impedance spectroscopy (EIS) and anodic polarization curves.

  16. Simulated HAZ continuous cooling transformation diagram of a bogie steel of high-speed railway

    Science.gov (United States)

    Liu, Yue; Chen, Hui; Liu, Yan; Hang, Zongqiu

    2017-07-01

    Simulated HAZ continuous cooling transformation (SH-CCT) diagram presents the start and end points of phase transformation and the relationships of the microstructures of HAZ, temperature and cooling rates. It is often used to assess the weldability of materials. In this paper, a weathering steel Q345C which is widely used in the bogies manufacturing was studied. The cooling times from 800∘C to 500∘C (t8/5) were from 3 s to 6000 s, aiming to study the microstructures under different cooling rates. Different methods such as color metallography were used to obtain the metallography images. The results show that ferrite nucleates preferentially at the prior austenite grain boundaries and grows along the grain boundaries with a lath-like distribution when t8/5 is 300 s. Austenite transforms into ferrite, pearlite and bainite with decreasing t8/5. Pearlite disappears completely when t8/5 = 150 s. Martensite gradually appears when t8/5 decreases to 30 s. The hardness increases with decreasing t8/5. The SH-CCT diagram indicates that the welding input and t8/5 should be taken into consideration when welding. This work provides the relationships of welding parameters and microstructures.

  17. Characterization of coarse bainite transformation in low carbon steel during simulated welding thermal cycles

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Liangyun, E-mail: lanly@me.neu.edu.cn [School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110819 (China); State Key Laboratory of Rolling Technology and Automation, Northeastern University, Shenyang 110819 (China); Kong, Xiangwei [School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110819 (China); Qiu, Chunlin [State Key Laboratory of Rolling Technology and Automation, Northeastern University, Shenyang 110819 (China)

    2015-07-15

    Coarse austenite to bainite transformation in low carbon steel under simulated welding thermal cycles was morphologically and crystallographically characterized by means of optical microscope, transmission electron microscope and electron backscattered diffraction technology. The results showed that the main microstructure changes from a mixture of lath martensite and bainitic ferrite to granular bainite with the increase in cooling time. The width of bainitic laths also increases gradually with the cooling time. For a welding thermal cycle with relatively short cooling time (e.g. t{sub 8/5} is 30 s), the main mode of variant grouping at the scale of individual prior austenite grains changes from Bain grouping to close-packed plane grouping with the progress of phase transformation, which results in inhomogeneous distribution of high angle boundaries. As the cooling time is increased, the Bain grouping of variants becomes predominant mode, which enlarges the effective grain size of product phase. - Highlights: • Main microstructure changes and the width of lath structure increases with cooling time. • Variant grouping changes from Bain zone to close-packed plane grouping with the transformation. • The change of variant grouping results in uneven distribution of high angle grain boundary. • Bain grouping is main mode for large heat input, which lowers the density of high angle boundary.

  18. Characterization of coarse bainite transformation in low carbon steel during simulated welding thermal cycles

    International Nuclear Information System (INIS)

    Lan, Liangyun; Kong, Xiangwei; Qiu, Chunlin

    2015-01-01

    Coarse austenite to bainite transformation in low carbon steel under simulated welding thermal cycles was morphologically and crystallographically characterized by means of optical microscope, transmission electron microscope and electron backscattered diffraction technology. The results showed that the main microstructure changes from a mixture of lath martensite and bainitic ferrite to granular bainite with the increase in cooling time. The width of bainitic laths also increases gradually with the cooling time. For a welding thermal cycle with relatively short cooling time (e.g. t 8/5 is 30 s), the main mode of variant grouping at the scale of individual prior austenite grains changes from Bain grouping to close-packed plane grouping with the progress of phase transformation, which results in inhomogeneous distribution of high angle boundaries. As the cooling time is increased, the Bain grouping of variants becomes predominant mode, which enlarges the effective grain size of product phase. - Highlights: • Main microstructure changes and the width of lath structure increases with cooling time. • Variant grouping changes from Bain zone to close-packed plane grouping with the transformation. • The change of variant grouping results in uneven distribution of high angle grain boundary. • Bain grouping is main mode for large heat input, which lowers the density of high angle boundary

  19. Effect of nitrite concentration on pit depth in carbon steel exposed to simulated radioactive waste

    International Nuclear Information System (INIS)

    Zapp, P.E.

    1997-01-01

    The growth of pits in carbon steel exposed to dilute (0.055 M nitrate-bearing) alkaline salt solutions that simulate radioactive waste was investigated in coupon immersion tests. Most coupons were tested in the as-received condition, with the remainder having been heat treated to produce an oxide film. Nitrite, which is an established pitting inhibitor in these solutions, was present in concentrations from 0 to 0.031 M to 0.16 M; the last concentration is known to prevent pitting initiation in the test solution at the 50 degrees C test temperature. The depths of the deepest pits on coupons of particular exposure conditions were measure microscopically and were analyzed as simple, type 1 extreme value statistical distributions, to predict the deepest expected pit in a radioactive waste tank subject to the test conditions. While the growth rate of pits could not be established from these tests, the absolute value of the deepest pits predicted is of the order of 100 mils after 448 days of exposure. The data indicate that even nitrite concentrations insufficient to prevent pitting have a beneficial effect on limiting the growth of deepest pits

  20. Image-based numerical simulation of the local cyclic deformation behavior around cast pore in steel

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Lihe, E-mail: dlhqian@yahoo.com [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University (China); National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University (China); Cui, Xiaona; Liu, Shuai [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University (China); National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University (China); Chen, Minan [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University (China); Ma, Penghui [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University (China); National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University (China); Xie, Honglan [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics (China); Zhang, Fucheng [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University (China); National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University (China); Meng, Jiangying [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University (China)

    2016-12-15

    The local cyclic stress/strain responses around an actual, irregular pore in cast Hadfield steel under fatigue loading are investigated numerically, and compared with those around a spherical and an ellipsoidal pore. The actual pore-containing model takes into account the real shape of the pore imaged via high-resolution synchrotron X-ray computed tomography and combines both isotropic hardening and Bauschinger effects by using the Chaboche's material model, which enables to realistically simulate the cyclic deformation behaviors around actual pore. The results show that the stress and strain energy density concentration factors (K{sub σ} and K{sub E}) around either an actual irregular pore or an idealized pore increase while the strain concentration factor (K{sub ε}) decreases slightly with increasing the number of fatigue cycles. However, all the three parameters, K{sub σ}, K{sub ε} and K{sub E}, around an actual pore are always several times larger than those around an idealized pore, whatever the number of fatigue cycles. It is suggested that the fatigue properties of cast pore-containing materials cannot be realistically evaluated with any idealized pore models. The feasibility of the methodology presented highlights the potential of its application in the micromechanical understanding of fatigue damage phenomena in cast pore-containing materials.

  1. Softening mechanisms of the AISI 410 martensitic stainless steel under hot torsion simulation

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Thiago Santana de; Silva, Eden Santos; Rodrigues, Samuel Filgueiras; Nascimento, Carmem Celia Francisco; Leal, Valdemar Silva; Reis, Gedeon Silva, E-mail: samuel.filgueiras@ifma.edu.br [Instituto Federal do Maranhao (PPGEM/IFMA), Sao Luis, MA (Brazil)

    2017-03-15

    This study investigated the softening mechanisms of the AISI 410 martensitic stainless steel during torsion simulation under isothermal continuous in the temperature range of 900 to 1150 °C and strain rates of 0.1 to 5.0s{sup -1}. In the first part of the curves, before the peak, the results show that the critical (ε-c) and peak (ε-p) strains are elevated for higher strain rate and lower temperatures contributing for higher strain hardening rate (h). Moreover, this indicated that dynamic recrystallization (DRX) and dynamic recovery (DRV) are not effective in this region. After the peak, the reductions in stresses are associated to the different DRX/DRV competitions. For lower temperatures and higher strain rates there is a delay in the DRX while the DRV is acting predominantly (with low Avrami exponent (n) and high t{sub 0.5}). The steady state was reached after large strains showing DRX grains, formation of retained austenite and the presence of chromium carbide (Cr{sub 23}C{sub 6}) and ferrite δ at the martensitic grain boundaries. These contribute for impairing the toughness and ductility on the material. The constitutive equations at the peak strain indicated changes in the deformation mechanism, with variable strain rate sensitivity (m), which affected the final microstructure. (author)

  2. Numerical simulations and experimental measurements of steel and ice impacts on concrete for acoustic interrogation of delaminations in bridge decks

    Energy Technology Data Exchange (ETDEWEB)

    Mazzeo, Brian A.; Patil, Anjali N.; Klis, Jeffrey M. [Brigham Young University, Department of Electrical and Computer Engineering, Provo, Utah, 84602 (United States); Hurd, Randy C.; Truscott, Tadd T. [Brigham Young University, Department of Mechanical Engineering, Provo, Utah, 84602 (United States); Guthrie, W. Spencer [Brigham Young University, Department of Civil and Environmental Engineering, Provo, Utah, 84602 (United States)

    2014-02-18

    Delaminations in bridge decks typically result from corrosion of the top mat of reinforcing steel, which leads to a localized separation of the concrete cover from the underlying concrete. Because delaminations cannot be detected using visual inspection, rapid, large-area interrogation methods are desired to characterize bridge decks without disruption to traffic, without the subjectivity inherent in existing methods, and with increased inspector safety. To this end, disposable impactors such as water droplets or ice chips can be dropped using automatic dispensers onto concrete surfaces to excite mechanical vibrations while acoustic responses can be recorded using air-coupled microphones. In this work, numerical simulations are used to characterize the flexural response of a model concrete bridge deck subject to both steel and ice impactors, and the results are compared with similar experiments performed in the laboratory on a partially delaminated concrete bridge deck slab. The simulations offer greater understanding of the kinetics of impacts and the responses of materials.

  3. Towards a quantification of stress corrosion mechanisms: numerical simulations of hydrogen-dislocations at the very crack tip; Vers une quantification des mecanismes de corrosion sous contrainte: simulations numeriques des interactions hydrogene-dislocations en pointe de fissure

    Energy Technology Data Exchange (ETDEWEB)

    Chateau, J.P

    1999-01-05

    We discuss the respective roles played by anodic dissolution and hydrogen in SCC mechanisms of f.c.c. materials, by studying the fracture of copper in nitrite for which we compare the results with that previously obtained in 316L steel in hot chloride. It is surprising to note that even the crystallographies at the scale of the micron are different, the macroscopic inclination of the fracture surfaces are the same. In the case of 316L steel, the formation of strong pile-ups in the presence of hydrogen leads to a zigzag fracture along alternated slip planes in the most general case. In the absence of hydrogen, as in copper, this mechanism effectively disappears. Furthermore, numerical simulations of crack shielding by dislocations emitted on one plane predict the macroscopic inclination. It shows that it is due to the mere dissolution which confines slip activity at the very crack tip in f.c.c. materials. In order to quantify the mechanism involved in 316L steel, we developed simulations which numerically solve the coupled diffusion and elasticity equations for hydrogen in the presence of a crack and shielding dislocations. They reproduce the mechanisms of hydrogen segregation on edge dislocations and of a localised softening effect by decreasing pair interactions. These mechanisms lead to i) a localisation of hydrogen embrittlement along the activated slip planes, ii) an increase of the dislocation density in pile-ups, and iii) a decrease of the cross slip probability. These three factors enhance micro-fracture at the head of a pile-up, which is responsible of thezigzag fracture. Introducing the free surface effects for hydrogen, we point out a new mechanism: the inhibition of dislocation sources at the crack tip, which is relevant with the brittle fracture surfaces observed in some cases in 316L steel. The quantification of these different mechanisms allows to give a relation between the local fracture possibility and the macroscopic parameters. A general law for

  4. Process simulation and experimental validation of Hot Metal Gas Forming with new press hardening steels

    Science.gov (United States)

    Paul, A.; Reuther, F.; Neumann, S.; Albert, A.; Landgrebe, D.

    2017-09-01

    One field in the work of the Fraunhofer Institute for Machine Tools and Forming Technology IWU in Chemnitz is industry applied research in Hot Metal Gas Forming, combined with press hardening in one process step. In this paper the results of investigations on new press hardening steels from SSAB AB (Docol®1800 Bor and Docol®2000 Bor) are presented. Hot tensile tests recorded by the project partner (University of West Bohemia, Faculty of Mechanical Engineering) were used to create a material model for thermo-mechanical forming simulations. For this purpose the provided raw data were converted into flow curve approximations of the real stress-real strain-curves for both materials and afterwards integrated in a LS-DYNA simulation model of Hot Metal Gas Forming with all relevant boundary conditions and sub-stages. Preliminary experimental tests were carried out using a tool at room temperature to permit evaluation of the forming behaviour of Docol 1800 Bor and Docol 2000 Bor tubes as well as validation of the simulation model. Using this demonstrator geometry (outer diameter 57 mm, tube length 300 mm, wall thickness 1.5 mm), the intention was to perform a series of tests with different furnace temperatures (from 870 °C to 1035 °C), maximum internal pressures (up to 67 MPa) and pressure build-up rates (up to 40 MPa/s) to evaluate the formability of Docol 1800 Bor and Docol 2000 Bor. Selected demonstrator parts produced in that way were subsequently analysed by wall thickness and hardness measurements. The tests were carried out using the completely modernized Dunkes/AP&T HS3-1500 hydroforming press at the Fraunhofer IWU. In summary, creating a consistent simulation model with all relevant sub-stages was successfully established in LS-DYNA. The computation results show a high correlation with the experimental data regarding the thinning behaviour. The Hot Metal Gas Forming of the demonstrator geometry was successfully established as well. Different hardness values

  5. Corrosion Performance of Carbon Steel in Simulated Pore Solution in the Presence of Micelles

    NARCIS (Netherlands)

    Hu, J.; Koleva, D.A.; De Wit, J.H.W.; Kolev, H.; Van Breugel, K.

    2011-01-01

    This study presents the results on the investigation of the corrosion behavior of carbon steel in model alkaline medium in the presence of very low concentration of polymeric nanoaggregates [0.0024 wt % polyethylene oxide (PEO)113-b-PS70 micelles]. The steel electrodes were investigated in chloride

  6. Discussing the precipitation behavior of {sigma} phase using diffusion equation and thermodynamic simulation in dissimilar stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Chih-Chun [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 402, Taiwan (China); Wu, Weite, E-mail: wwu@dragon.nchu.edu.t [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 402, Taiwan (China)

    2010-09-17

    Research highlights: This article concentrates the phase transformation in {delta} {yields} {sigma} in dissimilar stainless steels using the Vitek equation and thermodynamics simulation during the multi-pass welding. The phase transformation in {delta} {yields} {sigma} is very important to the properties of stainless steel composites. In this study, the diffusion behavior of Cr, Ni and Si in the {delta}, {sigma}, and {gamma} phases were discussed using the DSC analysis and diffusion equation calculation. This method has a novelty for discussing the phase transformation in {delta} {yields} {sigma} in the dissimilar stainless steel. We hope that we can give a scientific contribution for the phase transformation of the dissimilar stainless steels during the multi-pass welding. - Abstract: This study performed a precipitation examination of the {sigma} phase using the Vitek diffusion equation and thermodynamic simulation in dissimilar stainless steels during multi-pass welding. The results of the experiment demonstrate that the diffusion rates (D{sub Cr}{sup {delta}} and D{sub Ni}{sup {delta}}) of Cr and Ni are higher in {delta}-ferrite than (D{sub Cr}{sup {gamma}} and D{sub Ni}{sup {gamma}}) in the {gamma} phase and that they facilitate the precipitation of {sigma} phase in the third pass fusion zone. When the diffusion activation energy of Cr in {delta}-ferrite is equal to that of Ni in {delta}-ferrite (Q{sub dCr}{sup {delta}}=Q{sub dNi}{sup {delta}}), phase transformation of the {delta} {yields} {sigma} can be occurred.

  7. The Influence of Chemical Composition of Steels on the Numerical Simulation of a Continuesly Cast of Billet

    Directory of Open Access Journals (Sweden)

    František KAVIČKA

    2010-12-01

    Full Text Available The chemical composition of steels has significant influence on the actual concasting process, and on the accuracy of its numerical simulation and optimization. The chemical composition of steel affects the thermophysical properties (heat conductivity, specific heat capacity and density in the solid and liquid states often requires more time than the actual numerical calculation of the temperature fields of a continuously cast steel billet. Therefore, an analysis study of these thermophysical properties was conducted. The order of importance within the actual process and the accuracy of simulation were also determined. The order of significance of the chemical composition on thermophysical properties was determined with respect to the metallurgical length. The analysis was performed by means of a so-called calculation experiment, i.e. by means of the original numerical concasting model developed by the authors of this paper. It is convenient to conduct such an analysis in order to facilitate the simulation of each individual case of concasting, thus enhancing the process of optimization.

  8. Steel Moment-Resisting Frame Responses in Simulated Strong Ground Motions: or How I Learned to Stop Worrying and Love the Big One

    OpenAIRE

    Olsen, Anna

    2008-01-01

    This thesis studies the response of steel moment-resisting frame buildings in simulated strong ground motions. I collect 37 simulations of crustal earthquakes in California. These ground motions are applied to nonlinear finite element models of four types of steel moment frame buildings: six- or twenty-stories with either a stiffer, higherstrength design or a more flexible, lower-strength design. I also consider the presence of fracture-prone welds in each design. Since these b...

  9. Logistics simulation of in-bound raw materials to steel works for 2.4 mt expansion

    Energy Technology Data Exchange (ETDEWEB)

    Baijal, A.D.; Misbhra, O.P.; Das, S.; Banerjee, R.S.; Dash, S. [Tata Iron and Steel Company Ltd. (India)

    2005-07-01

    A logistics simulation was carried out to capture the possible scenarios of in-bound raw material traffic in light of Tata's Steel works 2.4 Mt expansion plan. Results from the simulation show that the number of tracks, track hoppers/tipplers and stockyard capacities are sufficient to handle the increased volumes of in-coming rakes. It also suggests that the number of locos can be rationalised without any adverse affect on the rake circuit times. 7 figs., 4 tabs.

  10. Self-healing phenomena on corroding steel in simulated pore water and mortar, substantiated via cyclic voltammetry and surface analysis

    Energy Technology Data Exchange (ETDEWEB)

    Koleva, D. A.; Breugel, K. van [Delft University of Technology, The Netherlands Faculty of CiTG, Department Materials and Environment, Delf (Netherlands); Hu, J. [School of Materials Science and Engineering, South China University of Technology, Guangzhou (China); Kolev, H. [Bulgarian Academy of Sciences, Institute of Catalysis, Sofia (Bulgaria)

    2013-07-01

    The application of polymeric nano-particles was investigated as an approach to control corrosion and/or self-heal corrosion damage on steel in simulated alkaline medium and reinforced mortar. The “self-healing agent”, present in the closed inner volume of PEO-b-PS vesicles was Ca-based and chosen as such due to the natural predominance of Ca in the investigated system. The vesicles’ concentration was 0.0024 wt.% in the model medium and 0.025 wt.% per cement weight for the case of mortar. Therefore, a “self-repair” or “self-healing” of the steel product layer solely due to the Ca- component is not realistic in view of these minimal concentrations. The most plausible mechanism is the nature of incorporation of the Ca-containing vesicles in the product layer, enhanced chloride binding effects and adsorption on active sites on the steel surface. A more uniform and stable surface layer, initial pitting formation and propagation, but consecutive “healing”, are evidenced by surface analysis and electrochemical response i.e. largely reduced anodic and corrosion currents and no further pit propagation are observed when Ca-containing vesicles are present in the model medium. Corrosion products-free steel/cement paste interface is relevant for the reinforced mortar, containing Ca-rich vesicles in contrast to vesicles-free and empty vesicles-containing matrix. Key words: corrosion; concrete; polymeric nano-particles; CVA; SEM; XRD; XPS.

  11. Corrosion kinetics of 316L stainless steel bipolar plate with chromiumcarbide coating in simulated PEMFC cathodic environment

    Directory of Open Access Journals (Sweden)

    N.B. Huang

    Full Text Available Stainless steel with chromium carbide coating is an ideal candidate for bipolar plates. However, the coating still cannot resist the corrosion of a proton exchange membrane fuel cell (PEMFC environment. In this work, the corrosion kinetics of 316L stainless steel with chromium carbide is investigated in simulated PEMFC cathodic environment by combining electrochemical tests with morphology and microstructure analysis. SEM results reveal that the steel’s surface is completely coated by Cr and chromium carbide but there are pinholes in the coating. After the coated 316L stainless steel is polarized, the diffraction peak of Fe oxide is found. EIS results indicate that the capacitive resistance and the reaction resistance first slowly decrease (2–32 h and then increase. The potentiostatic transient curve declines sharply within 2000 s and then decreases slightly. The pinholes, which exist in the coating, result in pitting corrosion. The corrosion kinetics of the coated 316L stainless steel are modeled and accords the following equation: i0 = 7.6341t−0.5, with the corrosion rate controlled by ion migration in the pinholes. Keywords: PEMFC, Metal bipolar plate, Chromium carbide coating, Corrosion kinetics, Pitting corrosion

  12. Effect of Ni on the corrosion resistance of bridge steel in a simulated hot and humid coastal-industrial atmosphere

    Science.gov (United States)

    Li, Dong-liang; Fu, Gui-qin; Zhu, Miao-yong; Li, Qing; Yin, Cheng-xiang

    2018-03-01

    The corrosion resistance of weathering bridge steels containing conventional contents of Ni (0.20wt%, 0.42wt%, 1.50wt%) and a higher content of Ni (3.55wt%) in a simulated hot and humid coastal-industrial atmosphere was investigated by corrosion depth loss, scanning electron microscopy-energy-dispersive X-ray spectroscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical methods. The results showed that, with increasing Ni content, the mechanical properties of the bridge steel were markedly improved, the welding parameters were satisfactory at room temperature, and the corrosion resistance was enhanced. When the Ni content was low (≤0.42wt%), the crystallization process of the corrosion products was substantially promoted, enhancing the stability of the rust layer. When the Ni content was higher ( 3.55wt%), the corrosion reaction of the steel quickly reached a balance, because the initial rapid corrosion induced the formation of a protective rust layer in the early stage. Simultaneously, NiO and NiFe2O2 were generated in large quantities; they not only formed a stable, compact, and continuous oxide protective layer, but also strongly inhibited the transformation process of the corrosion products. This inhibition reduced the structural changes in the rust layer, thereby enhancing the protection. However, when the Ni content ranged from 0.42wt% to 1.50wt%, the corrosion resistance of the bridge steel increased only slightly.

  13. Passive behaviour of alloy corrosion-resistant steel Cr10Mo1 in simulating concrete pore solutions with different pH

    International Nuclear Information System (INIS)

    Ai, Zhiyong; Jiang, Jinyang; Sun, Wei; Song, Dan; Ma, Han; Zhang, Jianchun; Wang, Danqian

    2016-01-01

    Highlights: • A new alloy corrosion-resistant steel Cr10Mo1 is developed for reinforcing rebar of concrete in severe environments. • The effects of pH on the passive behaviour of Cr10Mo1 steel compared with plain carbon steel were studied systematically by electrochemical techniques and surface analysis. • The mechanism for self-reinforcing passivity against carbonation of the corrosion-resistant steel is revealed. - Abstract: The passive behaviour of new alloy corrosion-resistant steel Cr10Mo1 and plain carbon steel (as a comparison) in simulating concrete pore solutions of different pH (ranging from 13.5 to 9.0) under open circuit potential conditions, was evaluated by various electrochemical techniques: potentiodynamic polarization, capacitance measurements and electrochemical impedance spectroscopy. The chemical composition and structure of passive films were investigated by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The electrochemical responses of passive films show that Cr10Mo1 steel has an increasing passivity with pH decreasing while carbon steel dose conversely, revealing carbonation does no negative effect on passivation of the corrosion-resistant steel. SIMS reveals that the passive film on the corrosion-resistant steel presents a bilayer structure: an outer layer mainly consisting of Fe oxides and hydroxides, and an inner layer enriched in Cr species, while only a Fe-concentrated layer for carbon steel. According to the XPS analysis results, as the pH decreases, more stable and protective Cr oxides are enriched in the film on Cr10Mo1 steel while Fe oxides gradually decompose. Higher content of Cr oxides in the film layer provides Cr10Mo1 corrosion-resistant steel more excellent passivity at lower pH.

  14. Passive behaviour of alloy corrosion-resistant steel Cr10Mo1 in simulating concrete pore solutions with different pH

    Energy Technology Data Exchange (ETDEWEB)

    Ai, Zhiyong, E-mail: 230139452@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Jiang, Jinyang, E-mail: jiangjinyang16@163.com [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Sun, Wei, E-mail: sunwei@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Song, Dan, E-mail: songdancharls@hhu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); College of Mechanics and Materials, Hohai University, Nanjing 210098, Jiangsu (China); Ma, Han, E-mail: mahan-iris@shasteel.cn [Research Institute of Jiangsu Shasteel Iron and Steel, Zhangjiagang 215625, Jiangsu (China); Zhang, Jianchun, E-mail: Zhangjc-iris@shasteel.cn [Research Institute of Jiangsu Shasteel Iron and Steel, Zhangjiagang 215625, Jiangsu (China); Wang, Danqian, E-mail: wonderbaba@126.com [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China)

    2016-12-15

    Highlights: • A new alloy corrosion-resistant steel Cr10Mo1 is developed for reinforcing rebar of concrete in severe environments. • The effects of pH on the passive behaviour of Cr10Mo1 steel compared with plain carbon steel were studied systematically by electrochemical techniques and surface analysis. • The mechanism for self-reinforcing passivity against carbonation of the corrosion-resistant steel is revealed. - Abstract: The passive behaviour of new alloy corrosion-resistant steel Cr10Mo1 and plain carbon steel (as a comparison) in simulating concrete pore solutions of different pH (ranging from 13.5 to 9.0) under open circuit potential conditions, was evaluated by various electrochemical techniques: potentiodynamic polarization, capacitance measurements and electrochemical impedance spectroscopy. The chemical composition and structure of passive films were investigated by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The electrochemical responses of passive films show that Cr10Mo1 steel has an increasing passivity with pH decreasing while carbon steel dose conversely, revealing carbonation does no negative effect on passivation of the corrosion-resistant steel. SIMS reveals that the passive film on the corrosion-resistant steel presents a bilayer structure: an outer layer mainly consisting of Fe oxides and hydroxides, and an inner layer enriched in Cr species, while only a Fe-concentrated layer for carbon steel. According to the XPS analysis results, as the pH decreases, more stable and protective Cr oxides are enriched in the film on Cr10Mo1 steel while Fe oxides gradually decompose. Higher content of Cr oxides in the film layer provides Cr10Mo1 corrosion-resistant steel more excellent passivity at lower pH.

  15. Apparatus for studying the diffusion of rare gases in stainless steel; Appareil pour etude de la diffusion des gaz rares dans l'acier inoxydable

    Energy Technology Data Exchange (ETDEWEB)

    Stohr, J A; Alfille, L [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    This apparatus enables measurements to be carried out on the diffusion of gaseous fission products and of gases in general across thin metallic walls at high temperatures. This work was initially intended to solve the problems involved in systems for detecting the rupture of a fuel element can (D.R.G.) by the diffusion of fission products through the cans at high temperatures. The extension of the work to other fields is envisaged. (author) [French] Cet appareil permet d'effectuer des mesures sur la diffusion des produits de fission gazeux, et des gaz en general, au travers de parois metalliques minces a haute temperature. Au depart, ce procede devait contribuer a resoudre les problemes poses aux systemes detecteurs de rupture de gaine (D.R.G.), par la diffusion des produits de fission au travers des gaines de cartouches a haute temperature. Son extension a d'autres etudes est envisagee. (auteur)

  16. RPV-1: A Virtual Test Reactor to simulate irradiation effects in light water reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Jumel, Stephanie; Van-Duysen, Jean Claude

    2005-01-01

    Many key components in commercial nuclear reactors are subject to neutron irradiation which modifies their mechanical properties. So far, the prediction of the in-service behavior and the lifetime of these components has required irradiations in so-called 'Experimental Test Reactors'. This predominantly empirical approach can now be supplemented by the development of physically based computer tools to simulate irradiation effects numerically. The devising of such tools, also called Virtual Test Reactors (VTRs), started in the framework of the REVE Project (REactor for Virtual Experiments). This project is a joint effort among Europe, the United States and Japan aimed at building VTRs able to simulate irradiation effects in pressure vessel steels and internal structures of LWRs. The European team has already built a first VTR, called RPV-1, devised for pressure vessel steels. Its inputs and outputs are similar to those of experimental irradiation programs carried out to assess the in-service behavior of reactor pressure vessels. RPV-1 is made of five codes and two databases which are linked up so as to receive, treat and/or convey data. A user friendly Python interface eases the running of the simulations and the visualization of the results. RPV-1 is sensitive to its inputs (neutron spectrum, temperature, ...) and provides results in conformity with experimental ones. The iterative improvement of RPV-1 has been started by the comparison of simulation results with the database of the IVAR experimental program led by the University of California Santa Barbara. These first successes led 40 European organizations to start developing RPV-2, an advanced version of RPV-1, as well as INTERN-1, a VTR devised to simulate irradiation effects in stainless steels, in a large effort (the PERFECT project) supported by the European Commission in the framework of the 6th Framework Program

  17. Phase transformation and local mechanical properties of TRIP steel in a simulated and real resistance spot weld process; Phasenumwandlung und lokale mechanische Eigenschaften von TRIP Stahl beim simulierten und realen Widerstandspunktschweissprozess

    Energy Technology Data Exchange (ETDEWEB)

    Brauser, Stephan

    2013-06-01

    area of spot welded TRIP steels. The established mechanical characteristics were used as input data for numerical simulation of the spot weld ductility and strength performance. Here, the attention was focused on the necessity of implementing mechanical characteristics of the heat-affected zone for realistic tensile shear test modelling. [German] TRIP Staehle realisieren durch eine unter mechanischer Beanspruchung hervorgerufene Phasenumwandlung von metastabilen Austenit in Martensit (TRIP-Effekt) hohe Festigkeiten bei gleichzeitig guten Verformungseigenschaften. Waehrend der Verarbeitung dieser Werkstoffe mittels Widerstandspunktschweissen koennen unter den prozessspezifischen extremen Aufheiz- und Abkuehlraten Modifikationen des Austenitanteils hervorgerufen werden die als Folge lokal zu einer Aenderung der mechanisch-technologischen Eigenschaften fuehren. Wesentliche Zielsetzung der vorliegenden Arbeit war daher die Analyse der Gefuegestruktur im Bereich einer Punktschweissverbindung hinsichtlich der Aenderung des Austenitanteils und den daraus resultierenden Aenderungen der lokalen mechanischen Eigenschaften unter besonderer Beruecksichtigung des TRIP-Effekts. Durch in-situ Beugungsuntersuchungen mittels hochenergetischer Synchrotronstrahlung erfolgte zunaechst die Quantifizierung des metastabilen Austenitanteils im unbehandelten Grundwerkstoff. Darauf aufbauend wurden unter definierten Temperaturprofilen in Ofenversuchen die grundlegenden Aspekte der thermisch bedingten Austenitumwandlung im Aufheiz- und Abkuehlprozess untersucht. Durch Gleeble-Versuche und Ofenexperimente wurden weiterfuehrend verschiedene Temperaturprofile mit unterschiedlichen im Punktschweissprozess lokal vorliegende Spitzentemperaturen genutzt um eine systematische Bewertung des Einflusses der Temperatur und der Aufheiz- sowie der Abkuehlbedingungen auf den Austenitgehalt unter realen Bedingungen zu ermoeglichen. Durch Korrelationsuntersuchungen zwischen den mechanischen Kennwerten thermisch

  18. A macroscopic model to simulate the mechanically induced martensitic transformation in metastable austenitic stainless steels

    NARCIS (Netherlands)

    Perdahcioglu, Emin Semih; Geijselaers, Hubertus J.M.

    2012-01-01

    Mechanically induced martensitic transformation and the associated transformation plasticity phenomena in austenitic stainless steels are studied. The mechanisms responsible for the transformation are investigated and put into perspective based on experimental evidence. The stress and strain

  19. Corrosion of steel drums containing simulated radioactive waste of low and intermediate level

    International Nuclear Information System (INIS)

    Farina, S.B.; Schulz Rodríguez, F.; Duffó, G.S.

    2013-01-01

    Ion-exchange resins are frequently used during the operation of nuclear power plants and constitute radioactive waste of low and intermediate level. For the final disposal inside the repository the resins are immobilized by cementation and placed inside steel drums. The eventful contamination of the resins with aggressive species may cause corrosion problems to the drums. In order to assess the incidence of this phenomenon and to estimate the lifespan of the steel drums, in the present work, the corrosion susceptibility of steel drums in contact with cemented ion-exchange resins contaminated with different aggressive species was studied. The aggressive species studied were chloride ions (main ionic species of concern) and sulphate ions (produced during radiolysis of the cationic exchange-resins after cementation). The corrosion rate of the steel was monitored over a time period of 900 days and a chemical and morphological analysis of the corrosion products formed on the steel in each condition was performed. When applying the results obtained in the present work to estimate the corrosion depth of the drums containing the cemented radioactive waste after a period of 300 years (foreseen durability of the Low and Intermediate Level Radioactive Waste facility in Argentina), it was found that in the most unfavourable case (high chloride contamination), the corrosion penetration will be considerably lower than the thickness of the wall of the steel drums. (author)

  20. Application of MMC model on simulation of shearing process of thick hot-rolled high strength steel plate

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Liang; Li, Shuhui [Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures, Shanghai Jiao Tong University, Shanghai 200240 (China); Yang, Bing; Gao, Yongsheng [Automotive Steel Research Institute, R and D Center, BaoShan Iron and Steel Co.,Ltd, Shanghai 201900 (China)

    2013-12-16

    Shear operation is widely used as the first step in sheet metal forming to cut the sheet or plate into the required size. The shear of thick hot-rolled High Strength Steel (HSS) requires large shearing force and the sheared edge quality is relatively poor because of the large thickness and high strength compared with the traditional low carbon steel. Bad sheared edge quality will easily lead to edge cracking during the post-forming process. This study investigates the shearing process of thick hot-rolled HSS plate metal, which is generally exploited as the beam of heavy trucks. The Modified Mohr-Coulomb fracture criterion (MMC) is employed in numerical simulation to calculate the initiation and propagation of cracks during the process evolution. Tensile specimens are designed to obtain various stress states in tension. Equivalent fracture strains are measured with Digital Image Correlation (DIC) equipment to constitute the fracture locus. Simulation of the tension test is carried out to check the fracture model. Then the MMC model is applied to the simulation of the shearing process, and the simulation results show that the MMC model predicts the ductile fracture successfully.

  1. Application of MMC model on simulation of shearing process of thick hot-rolled high strength steel plate

    International Nuclear Information System (INIS)

    Dong, Liang; Li, Shuhui; Yang, Bing; Gao, Yongsheng

    2013-01-01

    Shear operation is widely used as the first step in sheet metal forming to cut the sheet or plate into the required size. The shear of thick hot-rolled High Strength Steel (HSS) requires large shearing force and the sheared edge quality is relatively poor because of the large thickness and high strength compared with the traditional low carbon steel. Bad sheared edge quality will easily lead to edge cracking during the post-forming process. This study investigates the shearing process of thick hot-rolled HSS plate metal, which is generally exploited as the beam of heavy trucks. The Modified Mohr-Coulomb fracture criterion (MMC) is employed in numerical simulation to calculate the initiation and propagation of cracks during the process evolution. Tensile specimens are designed to obtain various stress states in tension. Equivalent fracture strains are measured with Digital Image Correlation (DIC) equipment to constitute the fracture locus. Simulation of the tension test is carried out to check the fracture model. Then the MMC model is applied to the simulation of the shearing process, and the simulation results show that the MMC model predicts the ductile fracture successfully

  2. Electrochemical Corrosion Behavior of Carbon Steel and Hot Dip Galvanized Steel in Simulated Concrete Solution with Different pH Values

    Directory of Open Access Journals (Sweden)

    Wanchen XIE

    2017-08-01

    Full Text Available Hot dip galvanizing technology is now widely used as a method of protection for steel rebars. The corrosion behaviors of Q235 carbon steel and hot galvanized steel in a Ca(OH2 solution with a pH from 10 to 13 was investigated by electrode potential and polarization curves testing. The results indicated that carbon steel and hot galvanized steel were all passivated in a strong alkaline solution. The electrode potential of hot dip galvanized steel was lower than that of carbon steel; thus, hot dip galvanized steel can provide very good anodic protection for carbon steel. However, when the pH value reached 12.5, a polarity reversal occurred under the condition of a certain potential. Hot dip galvanized coating became a cathode, and the corrosion of carbon steel accelerated. The electrochemical behaviors and passivation abilities of hot dip galvanized steel and carbon steel were affected by pH. The higher the pH value was, the more easily they were passivated.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16675

  3. Fatigue testing of weldable high strength steels under simulated service conditions

    Science.gov (United States)

    Tantbirojn, Natee

    There have been concerns over the effect of Cathodic Protection (CP) on weldable high strength steels employed in Jack-up production platform. The guidance provided by the Department of Energy HSE on higher strength steels, based on previous work, was to avoid overprotection as this could cause hydrogen embrittlement. However, the tests conducted so far at UCL for the SE702 type high strength steels (yields strength around 690 MPa) have shown that the effect of over protection on high strength steels may not be as severe as previously thought. For this thesis, SE702 high strength steels have been investigated in more detail. Thick (85mm) parent and ground welded plates were tested under constant amplitude in air and seawater with CP. Tests were also conducted on Thick (40mm) T-butt welded plates under variable amplitude loading in air and seawater with two CP levels (-800mV and -1050mV). Different backing materials (ceramic and metallic) for the welding process of the T-butt plates were also investigated. The variable amplitude sequences employed were generated using the Jack-up Offshore Standard load History (JOSH). The fatigue results are presented as crack growth and S/N curves. They were compared to the conventional offshore steel (BS 4360 50D). The results suggested that the fatigue life of the high strength steels was comparable to the BS 4360 50D steels. The effect of increasing the CP was found to be detrimental to the fatigue life but the effect was not large. The effect of CP was less noticeable in T-butt welded plates. However, in general, the effect of overprotection is not as detrimental to the Jack-up steels as previously thought. The load histories generated by JOSH were found to have some unfavourable characteristics. The framework is based on Markov Chain method and pseudo-random number generator for selecting sea-states. A study was carried out on the sequence generated by JOSH. The generated sequences were analysed for their validity for fatigue

  4. Simulation and analysis of the energy consumption of elevator systems; Simulation und Analyse des Energiebedarfs von Aufzugssystemen

    Energy Technology Data Exchange (ETDEWEB)

    Pletschen, Ingo; Rohr, Stephan [ThyssenKrupp Aufzugswerke GmbH, Neuhausen a.d.F. (Germany); Kennel, Ralph [Technische Univ. Muenchen (Germany)

    2011-07-01

    Elevator systems would be in principal a good example for a perpetuum mobile. While lifting loads and persons electrical energy is converted into potential energy and reconverted later. In practice these conversions are however lossy. So the aim for high energy efficiency is to minimize these losses. However, as a travel of an elevator consists in main parts of acceleration and deceleration, the exclusive consideration of the efficiency during constant speed is not sufficient. Thus a simulation environment is introduced which reliably determines the elevators' energy consumption. The simulation is validated at an elevator afterwards the different influences on the energy consumption of elevators are analyzed. (orig.)

  5. Monte Carlo simulation taking account of surface crack effect for stress corrosion cracking in a stainless steel SUS 304

    International Nuclear Information System (INIS)

    Tohgo, Keiichiro; Suzuki, Hiromitsu; Shimamura, Yoshinobu; Nakayama, Guen; Hirano, Takashi

    2008-01-01

    Stress corrosion cracking (SCC) in structural metal materials occurs by initiation and coalescence of micro cracks, subcritical crack propagation and multiple large crack formation or final failure under the combination of materials, stress and corrosive environment. In this paper, a Monte Carlo simulation for the process of SCC has been proposed based on the stochastic properties of micro crack initiation and fracture mechanics concept for crack coalescence and propagation. The emphasis in the model is put on the influence of semi-elliptical surface cracks. Numerical simulations are carried out based on CBB (creviced bent beam) test results of a sensitized stainless steel SUS 304 and the influence of micro crack initiation rate and coalescence condition on the simulation results is discussed. The numerical examples indicate the applicability of the present model to a prediction of the SCC behavior in real structures. (author)

  6. Proving the viability of manufacturing of multi-layer steel/vanadium alloy/steel composite tubes by numerical simulations and experiment

    Science.gov (United States)

    Nechaykina, T.; Nikulin, S.; Rozhnov, A.; Molotnikov, A.; Zavodchikov, S.; Estrin, Y.

    2018-05-01

    Vanadium alloys are promising structural materials for fuel cladding tubes for fast-neutron reactors. However, high solubility of oxygen and nitrogen in vanadium alloys at operating temperatures of 700 °C limits their application. In this work, we present a novel composite structure consisting of vanadium alloy V-4Ti-4Cr (provides high long-term strength of the material) and stainless steel Fe-0.2C-13Cr (as a corrosion resistant protective layer). It is produced by co-extrusion of these materials forming a three-layered tube. Finite element simulations were utilised to explore the influence of the various co-extrusion parameters on manufacturability of multi-layered tubes. Experimental verification of the numerical modelling was performed using co-extrusion with the process parameters suggested by the numerical simulations. Scanning electron microscopy and microhardness measurements revealed a defect-free diffusion layer at the interfaces between both materials indicating a good quality bonding for these co-extrusion conditions.

  7. Numerical simulation of two phase flows in heat exchangers; Simulation numerique des ecoulements diphasiques dans les echangeurs

    Energy Technology Data Exchange (ETDEWEB)

    Grandotto Biettoli, M

    2006-04-15

    The report presents globally the works done by the author in the thermohydraulic applied to nuclear reactors flows. It presents the studies done to the numerical simulation of the two phase flows in the steam generators and a finite element method to compute these flows. (author)

  8. 1-dimensional simulation of the radial compressor of a waste gas turbocharger; 1-dimensionale Simulation des Radialverdichters eines Abgasturboladers

    Energy Technology Data Exchange (ETDEWEB)

    Marques Gomes, Andre; Schmidt, Sebastian; Neumann, Jens [BMW Group, Muenchen (Germany)

    2011-07-01

    The simulation fo the thermodynamical properties of turbochargers in IC engines is mostly done with 1D gas exchange simulation tools, in which the turbocharger is represented by maps, or with 3D-CFD tools, in which a more precise geometrical detail of the charger can be considered. The present work aims for a modeling depth which lies between these 2 variants. This approach (''1D gas exchange simulation with 1D modeling of the turbocharger'') is not only motivated by enabling a better interaction, when compared to the map-based approach, between an IC engine and the turbocharger, but by distinctly reducing the modeling efforts and computing time when compared to the 3D-CFD approach. Within the study, a coarsely discretized model of a centrifugal compressor is built using only the model library of the commercial software GT-Power. For the validation regarding total pressure ratio and isentropic efficiency, the results of the stationary simulations of two different compressors are compared to CFD and measurement results. Differences can be seen only close to the choking limit of the compressor. The model was further used to demonstrate its applicability in extrapolated regions of the compressor map and in the instable operating range near the surge limit. (orig.)

  9. Sismonaute. Un système pour la détection et l'interprétation des fronts d'onde en simulation sismique Sismonaute. A System for Detecting and Interpreting Wave Fronts in Seismic Simulations

    Directory of Open Access Journals (Sweden)

    Junker U.

    2006-11-01

    Full Text Available Nous développons un système, dénommé SISMONAUTE, d'aide aux géophysiciens pour l'étude de la propagation des ondes dans un modèle postulé de sous-sol. Le système suit les fronts d'onde dans une série d'instantanés 2D produits par un simulateur numérique. De plus, il rétablit l'historique de l'onde, c'est-à-dire la séquence des réflexions, transmissions et diffractions qui représente des transformations qualitatives de l'onde. Cet historique est essentiel pour la comparaison des sismogrammes simulés et observés. Nous utilisons pour interpréter les données de simulation un système dirigé par les connaissances qui applique le raisonnement causal pour prédire, à chaque stade, de nouveaux fronts d'onde. Ces fronts prédits permettent une détection guidée des fronts d'onde sur les instantanés. We are developing a system, called SISMONAUTE, that supports a geophysicist in studying the propagation of waves in a postulated model of the subsoil. The system tracks the wave fronts in a sequence of 2D-snapshots produced by a numerical simulator. Furthermore, it recovers the history of a wave, i. e. the sequence of reflections, transmissions, and diffractions which represents qualitative changes of the wave. This history is essential for comparing simulated and observed seismograms. We use a knowledge-driven approach to interpret the simulated data. Using causal reasoning, the system predicts new wave fronts in each step. These predicted fronts enable a guided detection of wave fronts in the snapshots.

  10. Micromechanical analysis of martensite distribution on strain localization in dual phase steels by scanning electron microscopy and crystal plasticity simulation

    Energy Technology Data Exchange (ETDEWEB)

    Jafari, M. [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Ziaei-Rad, S., E-mail: szrad@cc.iut.ac.ir [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Saeidi, N. [Department of Materials Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Jamshidian, M. [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)

    2016-07-18

    The morphology and distribution of the dispersed martensite islands in the ferrite matrix plays a key role in the formation of shear bands in dual phase steels. In this study, we investigate the relationship between the martensite dispersion and the strain localization regions due to the formation of shear bands in fine-grained DP 780 steel, employing experimental observations as well as numerical simulations. SEM studies of the deformed microstructure showed that voids nucleated at ferrite-martensite interface within larger ferrite grains and regions with low local martensite fraction. The experimental results were precisely analyzed by finite element simulations based on the theory of crystal plasticity. A parametric study was then performed to obtain a deeper insight in to the effect of martensite dispersion on the strain localization of the neighboring ferrite. Crystal plasticity simulation results revealed that in a more regular structure compared to a random structure, a greater region of the ferrite phase contributes to accommodate plasticity. In addition, these regions limit the formation of main shear bands by creating barriers against stress concentration regions, results in lower growth and interaction of stress concentration regions with each others.

  11. Design of welding parameters for laser welding of thin-walled stainless steel tubes using numerical simulation

    Science.gov (United States)

    Nagy, M.; Behúlová, M.

    2017-11-01

    Nowadays, the laser technology is used in a wide spectrum of applications, especially in engineering, electronics, medicine, automotive, aeronautic or military industries. In the field of mechanical engineering, the laser technology reaches the biggest increase in the automotive industry, mainly due to the introduction of automation utilizing 5-axial movements. Modelling and numerical simulation of laser welding processes has been exploited with many advantages for the investigation of physical principles and complex phenomena connected with this joining technology. The paper is focused on the application of numerical simulation to the design of welding parameters for the circumferential laser welding of thin-walled exhaust pipes from theAISI 304 steel for automotive industry. Using the developed and experimentally verified simulation model for laser welding of tubes, the influence of welding parameters including the laser velocity from 30 mm.s-1 to 60 mm.s-1 and the laser power from 500 W to 1200 W on the temperature fields and dimensions of fusion zone was investigated using the program code ANSYS. Based on obtained results, the welding schedule for the laser beam welding of thin-walled tubes from the AISI 304 steel was suggested.

  12. RPV-1: a first virtual reactor to simulate irradiation effects in light water reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Jumel, St.

    2005-01-01

    The presented work was aimed at building a first VTR (virtual test reactor) to simulate irradiation effects in pressure vessel steels of nuclear reactor. It mainly consisted in: - modeling the formation of the irradiation induced damage in such steels, as well as their plasticity behavior - selecting codes and models to carry out the simulations of the involved mechanisms. Since the main focus was to build a first tool (rather than a perfect tool), it was decided to use, as much as possible, existing codes and models in spite of their imperfections. - developing and parameterizing two missing codes: INCAS and DUPAIR. - proposing an architecture to link the selected codes and models. - constructing and validating the tool. RPV-1 is made of five codes and two databases which are linked up so as to receive, treat and/or transmit data. A user friendly Python interface facilitates the running of the simulations and the visualization of the results. RPV-1 relies on many simplifications and approximations and has to be considered as a prototype aimed at clearing the way. According to the functionalities targeted for RPV-1, the main weakness is a bad Ni and Mn sensitivity. However, the tool can already be used for many applications (understanding of experimental results, assessment of effects of material and irradiation conditions,....). (O.M.)

  13. Corrosion Behavior of Low-C Medium-Mn Steel in Simulated Marine Immersion and Splash Zone Environment

    Science.gov (United States)

    Zhang, Dazheng; Gao, Xiuhua; Su, Guanqiao; Du, Linxiu; Liu, Zhenguang; Hu, Jun

    2017-05-01

    The corrosion behavior of low-C medium-Mn steel in simulated marine immersion and splash zone environment was studied by static immersion corrosion experiment and wet-dry cyclic corrosion experiment, respectively. Corrosion rate, corrosion products, surface morphology, cross-sectional morphology, elemental distribution, potentiodynamic polarization curves and electrochemical impedance spectra were used to elucidate the corrosion behavior of low-C medium-Mn steel. The results show that corrosion rate in immersion zone is much less than that in splash zone owing to its relatively mild environment. Manganese compounds are detected in the corrosion products and only appeared in splash zone environment, which can deteriorate the protective effect of rust layer. With the extension of exposure time, corrosion products are gradually transformed into dense and thick corrosion rust from the loose and porous one in these two environments. But in splash zone environment, alloying elements of Mn appear significant enrichment in the rust layer, which decrease the corrosion resistance of the steel.

  14. Modelling and simulation of the influence of forming processes on the structural behavior of high strength steels

    International Nuclear Information System (INIS)

    Gelin, J.C.; Thibaud, S.; Boudeau, N.

    2005-01-01

    The paper first describes experiments and modeling concerning the identification of material behavior for high strength steels with phase transformations associated to plastic deformation. The experiments consist of tensile and bulging tests carried out on 316L stainless steels and TRIP 700 steels used in automotive industry. These experiments have permitted to determine the hardening curves of such materials vs. the martensite volume fraction associated to plastic deformation. It has been demonstrated that the stress triaxiality has a major role in the martenstic transformation and a model is proposed to define the flow stress vs. effective strain accounting planar anisotropy and variation of martenstic volume fraction. Then a plasticity model has been proposed in an anisotropic form and the related flow rules have been defined. The resulting model has been implemented in different finite elements software, and applied in numerical simulations of stamping and hydroforming of typical components to prove the effects of forming processes on the resulting properties of the components. Finally, the structural behavior of the resulting components is investigated and the effects of forming processes on the resulting structural behaviour are analyzed. Two cases are presented, one concerns the deep drawing of a cylindrical cup and the other concerns the stamping of a closed U channel used as a structural part for crash frames. Is has been clearly proved that the variation of martensite volume fraction arising during processing has a strong influence on the resulting behaviour of the parts considering springback and crash resistance

  15. Propagation of thermal neutrons in mock-up screw-shaped steel elements with water protection; Propagation des neutrons thermiques dans des fausses cartouches d'acier en helice dans une protection d'eau. Programme tournesol 3

    Energy Technology Data Exchange (ETDEWEB)

    Devillers, C L; Lanore, J M [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-07-01

    This report treats the streaming of thermal neutrons in a cylindrical duct in light water. The duct contains a spiral iron shield. Transmission and reflection matrices are used to describe the probabilities for the thermal neutrons to be absorbed or to be scattered on the surfaces. The neutron paths across the void are represented by geometrical matrices. The numerical resolution is performed by the Monte-Carlo method. (authors) [French] Dans ce rapport on traite un probleme de fuites de neutrons thermiques dans un canal cylindrique plonge dans l'eau et obture par un ecran helicoidal en acier. On utilise des matrices de transmission-reflexion pour decrire les probabilites d'absorption et de diffusion des neutrons sur les parois et l'helicoide et des matrices de correspondance geometrique pour representer la propagation dans le vide. La resolution numerique se fait par une methode de Monte-Carlo. (auteur)

  16. Numerical simulation of Cr2N age-precipitation in high nitrogen stainless steels

    International Nuclear Information System (INIS)

    Dai, Q.X.; Yuan, Z.Z.; Luo, X.M.; Cheng, X.N.

    2004-01-01

    At the temperature raging from 700 to 950 deg. C, the Cr 2 N age-precipitation in high nitrogen austenitic stainless steels Fe24Mn18Cr3Ni0.62N was investigated in this paper. A qualitative mathematical model of Cr 2 N age-precipitation, ln t S = f (Me,1/T), was established based on the thermodynamics and kinetics and phase transformation theories. Satisfactory results were obtained by means of the test of artificial neural network. This mathematical model can be applied to the calculation design and predication of Cr 2 N age-precipitation in high nitrogen stainless steels

  17. The mechanical properties and microstructures of vanadium bearing high strength dual phase steels processed with continuous galvanizing line simulations

    Science.gov (United States)

    Gong, Yu

    For galvanized or galvannealed steels to be commercially successful, they must exhibit several attributes: (i) easy and inexpensive processing in the hot mill, cold mill and on the coating line, (ii) high strength with good formability and spot weldability, and (iii) good corrosion resistance. At the beginning of this thesis, compositions with a common base but containing various additions of V or Nb with or without high N were designed and subjected to Gleeble simulations of different galvanizing(GI), galvannealing(GA) and supercooling processing. The results revealed the phase balance was strongly influenced by the different microalloying additions, while the strengths of each phase were somewhat less affected. Our research revealed that the amount of austenite formed during intercritical annealing can be strongly influenced by the annealing temperature and the pre-annealing conditions of the hot band (coiling temperature) and cold band (% cold reduction). In the late part of this thesis, the base composition was a low carbon steel which would exhibit good spot weldability. To this steel were added two levels of Cr and Mo for strengthening the ferrite and increasing the hardenability of intercritically formed austenite. Also, these steels were produced with and without the addition of vanadium in an effort to further increase the strength. Since earlier studies revealed a relationship between the nature of the starting cold rolled microstructure and the response to CGL processing, the variables of hot band coiling temperature and level of cold reduction prior to annealing were also studied. Finally, in an effort to increase strength and ductility of both the final sheet (general formability) and the sheared edges of cold punched holes (local formability), a new thermal path was developed that replaced the conventional GI ferrite-martensite microstructure with a new ferrite-martensite-tempered martensite and retained austenite microstructure. The new

  18. The Passive Film Growth Mechanism of New Corrosion-Resistant Steel Rebar in Simulated Concrete Pore Solution: Nanometer Structure and Electrochemical Study.

    Science.gov (United States)

    Jiang, Jin-Yang; Wang, Danqian; Chu, Hong-Yan; Ma, Han; Liu, Yao; Gao, Yun; Shi, Jinjie; Sun, Wei

    2017-04-14

    An elaborative study was carried out on the growth mechanism and properties of the passive film for a new kind of alloyed corrosion-resistant steel (CR steel). The passive film naturally formed in simulated concrete pore solutions (pH = 13.3). The corrosion resistance was evaluated by various methods including open circuit potential (OCP), linear polarization resistance (LPR) measurements, and electrochemical impedance spectroscopy (EIS). Meanwhile, the 2205 duplex stainless steel (SS steel) was evaluated for comparison. Moreover, the passive film with CR steel was studied by means of X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Atomic Force Microscope (AFM), and the Mott‑Schottky approach. The results showed that the excellent passivity of CR steel could be detected in a high alkaline environment. The grain boundaries between the fine passive film particles lead to increasing Cr oxide content in the later passivation stage. The filling of cation vacancies in the later passivation stage as well as the orderly crystalized inner layer contributed to the excellent corrosion resistance of CR steel. A passive film growth model for CR steel was proposed.

  19. Simulation analysis of impact tests of steel plate reinforced concrete and reinforced concrete slabs against aircraft impact and its validation with experimental results

    International Nuclear Information System (INIS)

    Sadiq, Muhammad; Xiu Yun, Zhu; Rong, Pan

    2014-01-01

    Highlights: • Simulation analysis is carried out with two constitutive concrete models. • Winfrith model can better simulate nonlinear response of concrete than CSCM model. • Performance of steel plate concrete is better than reinforced concrete. • Thickness of safety related structures can be reduced by adopting steel plates. • Analysis results, mainly concrete material models should be validated. - Abstract: The steel plate reinforced concrete and reinforced concrete structures are used in nuclear power plants for protection against impact of an aircraft. In order to compare the impact resistance performance of steel plate reinforced concrete and reinforced concrete slabs panels, simulation analysis of 1/7.5 scale model impact tests is carried out by using finite element code ANSYS/LS-DYNA. The damage modes of all finite element models, velocity time history curves of the aircraft engine and damage to aircraft model are compared with the impact test results of steel plate reinforced concrete and reinforced concrete slab panels. The results indicate that finite element simulation results correlate well with the experimental results especially for constitutive winfrith concrete model. Also, the impact resistance performance of steel plate reinforced concrete slab panels is better than reinforced concrete slab panels, particularly the rear face steel plate is very effective in preventing the perforation and scabbing of concrete than conventional reinforced concrete structures. In this way, the thickness of steel plate reinforced concrete structures can be reduced in important structures like nuclear power plants against impact of aircraft. It also demonstrates the methodology to validate the analysis procedure with experimental and analytical studies. It may be effectively employed to predict the precise response of safety related structures against aircraft impact

  20. Application of stochastic approach based on Monte Carlo (MC) simulation for life cycle inventory (LCI) to the steel process chain: Case study

    Energy Technology Data Exchange (ETDEWEB)

    Bieda, Bogusław

    2014-05-01

    The purpose of the paper is to present the results of application of stochastic approach based on Monte Carlo (MC) simulation for life cycle inventory (LCI) data of Mittal Steel Poland (MSP) complex in Kraków, Poland. In order to assess the uncertainty, the software CrystalBall® (CB), which is associated with Microsoft® Excel spreadsheet model, is used. The framework of the study was originally carried out for 2005. The total production of steel, coke, pig iron, sinter, slabs from continuous steel casting (CSC), sheets from hot rolling mill (HRM) and blast furnace gas, collected in 2005 from MSP was analyzed and used for MC simulation of the LCI model. In order to describe random nature of all main products used in this study, normal distribution has been applied. The results of the simulation (10,000 trials) performed with the use of CB consist of frequency charts and statistical reports. The results of this study can be used as the first step in performing a full LCA analysis in the steel industry. Further, it is concluded that the stochastic approach is a powerful method for quantifying parameter uncertainty in LCA/LCI studies and it can be applied to any steel industry. The results obtained from this study can help practitioners and decision-makers in the steel production management. - Highlights: • The benefits of Monte Carlo simulation are examined. • The normal probability distribution is studied. • LCI data on Mittal Steel Poland (MSP) complex in Kraków, Poland dates back to 2005. • This is the first assessment of the LCI uncertainties in the Polish steel industry.

  1. Simulative Testing of Friction and Lubrication in Cold Forging of Steel and Aluminum

    DEFF Research Database (Denmark)

    Ceron, Ermanno; Bay, Niels; Aida, Tetsuo

    2012-01-01

    torque during testing combined with an analysis of the sliding velocity distribution along the punch nose. The latter is determined by FE analysis of the test. Results show friction stress for unalloyed low C-steel provided with different types of lubricants, i.e. phosphate coating plus soap, phosphate...

  2. Creep properties of simulated heat-affected zone of HR3C austenitic steel

    Czech Academy of Sciences Publication Activity Database

    Sklenička, Václav; Kuchařová, Květa; Kvapilová, Marie; Svoboda, Milan; Král, Petr; Dvořák, Jiří

    2017-01-01

    Roč. 128, JUN (2017), s. 238-247 ISSN 1044-5803 R&D Projects: GA MŠk(CZ) LQ1601 Institutional support: RVO:68081723 Keywords : HR3C steel * Welding * Heat affected zone * Creep * Microstructure * Fractography Subject RIV: JG - Metallurgy OBOR OECD: Materials engineering Impact factor: 2.714, year: 2016

  3. Microstructural and mechanical characterization of the ferritic martensitic steel eurofer'97 after simulated service conditions

    International Nuclear Information System (INIS)

    Fernandez, P.; Lancha, A. M.; Lapena, J.

    2002-01-01

    This report details the metallurgical characterization of the Eurofer'97 steel thermally aged in the range of temperatures from 400 degree centigrade to 600 degree centigrade up to 10000 H, microstructural studies and mechanical testing (hardness, tensile, Charpy and low cycle fatigue test) have been carried out

  4. MATHEMATICAL SIMULATION OF ARGON MIXING PROCESSES AND STEEL SATURATION WITH CARBON IN LADLE

    Directory of Open Access Journals (Sweden)

    A. N. Chichko

    2006-01-01

    Full Text Available The mathematical model for dissolution process of a powder material in steel melt is proposed in the paper. The model permits to take into account mixing hydrodynamics on the basis of the Navier-Stokes equations. One of the industrial out-of-furnace treatment schemes taken as an example demonstrates the opportunities to model a carbon dissolution in a ladle.

  5. Application of stochastic approach based on Monte Carlo (MC) simulation for life cycle inventory (LCI) to the steel process chain: case study.

    Science.gov (United States)

    Bieda, Bogusław

    2014-05-15

    The purpose of the paper is to present the results of application of stochastic approach based on Monte Carlo (MC) simulation for life cycle inventory (LCI) data of Mittal Steel Poland (MSP) complex in Kraków, Poland. In order to assess the uncertainty, the software CrystalBall® (CB), which is associated with Microsoft® Excel spreadsheet model, is used. The framework of the study was originally carried out for 2005. The total production of steel, coke, pig iron, sinter, slabs from continuous steel casting (CSC), sheets from hot rolling mill (HRM) and blast furnace gas, collected in 2005 from MSP was analyzed and used for MC simulation of the LCI model. In order to describe random nature of all main products used in this study, normal distribution has been applied. The results of the simulation (10,000 trials) performed with the use of CB consist of frequency charts and statistical reports. The results of this study can be used as the first step in performing a full LCA analysis in the steel industry. Further, it is concluded that the stochastic approach is a powerful method for quantifying parameter uncertainty in LCA/LCI studies and it can be applied to any steel industry. The results obtained from this study can help practitioners and decision-makers in the steel production management. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Sur la modélisation et la simulation de liaisons soumises à des chocs pyrotechniques

    OpenAIRE

    Derumaux , Marc

    2004-01-01

    The presented work deals with fast dynamic simulation of non linear joints. An original industrial context illustrates the process, consisting in analyzing, with an eye to prediction, consequences of a stage separation on the Ariane 5 launcher. A pyrotechnic device cuts the structure along a breaking split, which generates a strong shock wave propagating up to the satellites. A two scales approach is proposed to perform an accurate calculation of the joints behavior (place of strong non linea...

  7. The Role of the Bainitic Packet in Control of Impact Toughness in a Simulated CGHAZ of X90 Pipeline Steel

    Directory of Open Access Journals (Sweden)

    Bin Guo

    2016-10-01

    Full Text Available X90 pipeline steel was processed with the simulated coarse grain heat affect zone (CGHAZ thermal cycle with heat input varying from 30 kJ/cm to 60 kJ/cm, the microstructures were investigated by means of optical microscope (OM, scanning electron microscope (SEM, electron backscattering diffraction (EBSD, and transmission electron microscope (TEM, and the impact properties were evaluated from the welding thermal cycle treated samples. The results indicate that the microstructure is primarily composed of lath bainite. When decreasing the heat input, both bainite packet and block are significantly refined, and the toughness has an increased tendency due to the grain refinement. The fracture surfaces all present cleavage fracture for the samples with different heat inputs. Moreover, the average cleavage facet size for the CGHAZ is nearly equal to the average bainite packet size, and the bainitic packet boundary can strongly impede the crack propagation, indicating that the bainitic packet is the most effective unit in control of impact toughness in the simulated CGHAZ of X90 pipeline steel.

  8. Finite Element Modeling of an Aircraft Tire Rolling on a Steel Drum: Experimental Investigations and Numerical Simulations

    Directory of Open Access Journals (Sweden)

    Iulian Rosu

    2018-04-01

    Full Text Available The aim of this study is to investigate the thermal evolution of an aircraft tire rolling at high velocities up to take off values. As this kind of experiment is difficult to realize on a real runway, experimental tests were realized on aircraft tires rolling on a steel drum. The rotating drum facility allows to apply variable velocities beyond the take off limits, at fixed skidding angles and loadings. The rolling conditions, vertical loading, velocity and cornering conditions were adopted to correspond to the real conditions of an aircraft tire running or skidding on a flat runway. In the experimental part, the influence of skidding angle, velocity and loading on the thermal evolution of the tire tread were investigated. The thermo-mechanical finite element analysis of a pneumatic radial tire structure was performed taking into account the hyper-viscoelastic rubber behavior, with heating mechanisms developed by the inelastic deformation and by friction. Three-dimensional finite element simulations of an aircraft tire rolling on a steel drum were carried out using Abaqus/Standard finite element solver. The comparison of the temperature distribution on the tire tread between numerical results and the experimental data shows the same overall tendencies. The good correlation between numerical and experimental data shows that numerical simulation could predict the thermal evolution of the tire in critical situations. The authors would like to mention that for confidentiality reason, certain numerical data could not be revealed.

  9. Detection of localized and general corrosion of mild steel in simulated defense nuclear waste solutions using electrochemical noise analysis

    International Nuclear Information System (INIS)

    Edgemon, G.L.; Ohl, P.C.; Bell, G.E.C.; Wilson, D.F.

    1995-12-01

    Underground waste tanks fabricated from mild steel store more than 60 million gallons of radioactive waste from 50 years of weapons production. Leaks are suspected in a significant number of tanks. The probable modes of corrosion failures are reported to be localized corrosion (e.g. nitrate stress corrosion cracking and pitting). The use of electrochemical noise (EN) for the monitoring and detection of localized corrosion processes has received considerable attention and application over the last several years. Proof of principle laboratory tests were conducted to verify the capability of EN evaluation to detect localized corrosion and to compare the predictions of general corrosion obtained from EN with those derived from other sources. Simple, pre-fabricated flat and U-bend specimens of steel alloys A516-Grade 60 (UNS K02100) and A537-CL 1 (UNS K02400) were immersed in temperature controlled simulated waste solutions. The simulated waste solution was either 5M NaNO 3 with 0.3M NaOH at 90 C or 11M NaNO 3 with 0.15M NaOH at 95 C. The electrochemical noise activity from the specimens was monitored and recorded for periods ranging between 140 and 240 hours. At the end of each test period, the specimens were metallographically examined to correlated EN data with corrosion damage

  10. Simulation Study on the Deflection Response of the 921A Steel thin plate under Explosive Impact Load

    Science.gov (United States)

    Zhang, Yu-Xiang; Chen, Fang; Han, Yan

    2018-03-01

    The Ship cabin would be subject to high-intensity shock wave load when it is attacked by anti-ship weapons, causing its side board damaged. The time course of the deflection of the thin plate made of 921A steel in different initial conditions under the impact load is researched by theoretical analysis and numerical simulation. According to the theory of elastic-plastic deformation of the thin plate, the dynamic response equation of the thin plate under the explosion impact load is established with the method of energy, and the theoretical calculation value is compared with the result from the simulation method. It proved that the theoretical calculation method has better reliability and accuracy in different boundary size.

  11. Modelling and numerical simulation of the General Dynamic Equation of aerosols; Modelisation et simulation des aerosols atmospheriques

    Energy Technology Data Exchange (ETDEWEB)

    Debry, E.

    2005-01-15

    Chemical-transport models are now able to describe in a realistic way gaseous pollutants behavior in the atmosphere. Nevertheless atmospheric pollution also exists as fine suspended particles, called aerosols, which interact with gaseous phase, solar radiation, and have their own dynamic behavior. The goal of this thesis is the modelling and numerical simulation of the General Dynamic Equation of aerosols (GDE). Part I deals with some theoretical aspects of aerosol modelling. Part II is dedicated to the building of one size resolved aerosol model (SIREAM). In part III we perform the reduction of this model in order to use it in dispersion models as POLAIR3D. Several modelling issues are still opened: organic aerosol matter, externally mixed aerosols, coupling with turbulent mixing, and nano-particles. (author)

  12. Design, simulation and construction of the GERDA-muon veto; Design, Simulation und Aufbau des GERDA-Myonvetos

    Energy Technology Data Exchange (ETDEWEB)

    Knapp, Markus Alexander

    2009-10-09

    The GERmanium Detector Array (Gerda) is a experiment searching for the neutrinoless double beta decay of {sup 76}Ge. This very rare weakly interacting process is predicted to occur if the neutrino exhibits a mass and is a Majorana particle; i.e. it is its own antiparticle. Although the double beta decay with emission of two neutrinos has been found in several nuclei, there is at this moment only a part of the Heidelberg-Moscow Collaboration claiming to have observed the neutrinoless double beta decay. The best limit for the half life currently is T{sub 1/2} > 1.2.10{sup 25} y. Gerda will expose about 15 kg.y of enriched germanium detectors from the Heidelberg-Moscow and IGEX crystals in phase I. In this phase, it will be able to test the claim within one year, due to reduced background by a factor 10. In phase II about 100 kg.y of data will be accumulated, leading to T{sub 1/2} > 2.10{sup 26} y due to an additional reduction of the background by a factor of 10. For a high sensitivity at these half lives, it is necessary to detect the corresponding rare events. Therefore background reduction to a rate of 10{sup -3} (counts)/(keV.kg.year) is of utmost importance. Therefore different background identification methods, like pulseshape analysis or a muon veto will be used. In this work, the development of the Cherenkov muon veto detectors is presented. First design studies will be shown, including extensive Monte-Carlo simulations. These simulations were also used to optimize the trigger conditions of the data acquisition, to detect all muons, that cause an energy deposition in the germanium detectors. Finally the on site construction at the Laboratori Nazionali del Gran Sasso in Italy will be described. (orig.)

  13. Plasticity and fracture modeling of three-layer steel composite Tribond® 1200 for crash simulation

    NARCIS (Netherlands)

    Eller, Tom; Ramaker, Kenny; Greve, Lars; Andres, M.T.; Hazrati Marangalou, Javad; van den Boogaard, Antonius H.

    2017-01-01

    A constitutive model is presented for the three-layer steel composite Tribond® 1200. Tribond® is a hot forming steel which consists of three layers: a high strength steel core between two outer layers of ductile low strength steel. The model is designed to provide an accurate prediction of the

  14. Stainless steel corrosion in conditions simulating WWER-1000 primary coolant. Corrosion behaviour in mixed core

    International Nuclear Information System (INIS)

    Krasnorutskij, V.S.; Petel'guzov, I.A.; Gritsina, V.M.; Zuek, V.A.; Tret'yakov, M.V.; Rud', R.A.; Svichkar', N.V.; Slabospitskaya, E.A.; Ishchenko, N.I.

    2011-01-01

    Research into corrosion kinetics of austenitic stainless steels (06Cr18Ni10Ti, 08Cr18Ni10Ti, 12Cr18Ni10Ti) in medium which corresponds to composition and parameters of WWER-1000 primary coolant with different pH values in autoclave out-pile conditions during 14000 hours is given. Surface of oxide films on stainless steels is investigated. Visual inspection of Westinghouse and TVEL fuel was carried out after 4 cycles in WWER-1000 primary water chemistry conditions at South Ukraine NPP. Westinghouse and TVEL fuel cladding materials possess high corrosion resistance. Blushing of weldments was observed. No visual corrosion defects or deposits were observed on fuel rods.

  15. Fatigue-crack growth behavior of Type 347 stainless steels under simulated PWR water conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Seokmin; Min, Ki-Deuk; Yoon, Ji-Hyun; Kim, Min-Chul; Lee, Bong-Sang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Fatigue crack growth rate (FCGR) curve of stainless steel exists in ASME code section XI, but it is still not considering the environmental effects. The longer time nuclear power plant is operated, the more the environmental degradation issues of materials pop up. There are some researches on fatigue crack growth rate of S304 and S316, but researches of FCGR of S347 used in Korea nuclear power plant are insufficient. In this study, the FCGR of S347 stainless steel was evaluated in the PWR high temperature water conditions. The FCGRs of S347 stainless steel under pressurized-water conditions were measured by using compact-tension (CT) specimens at different levels of dissolved oxygen (DO) and frequency. 1. FCGRs of SS347 were slower than that in ASME XI and environmental effect did not occur when frequency was higher than 1Hz. 2. Fatigue crack growth is accelerated by corrosion fatigue and it is more severe when frequency is slower than 0.1Hz. 3. Increase of crack tip opening time increased corrosion fatigue and it deteriorated environmental fatigue properties.

  16. Marine Shaft Steels (AISI 4140 and AISI 5120 Predicted Fracture Toughness by FE Simulation

    Directory of Open Access Journals (Sweden)

    Goran VUKELIC

    2017-02-01

    Full Text Available Optimal selection of material can be considered as one of the most critical steps in engineering design process. That is especially emphasized when dealing with constructions that operate in marine environment; high stresses and harsh operating conditions assert the importance of proper material characterization before its selection. This paper presents comparison of two types of steel usually used in marine shaft manufacturing, chromium-molybdenum steel AISI 4140 and chromium low-alloy steel AISI 5120. Comparison was made using numerically determined J-integral, an important fracture mechanics parameter. J-integral values are determined numerically using finite element (FE stress analysis results of compact tensile (CT and single-edge notched bend (SENB type specimens usually used in standardized J-integral experimental procedures. Obtained J values are plotted versus specimen crack growth values (Δa for different specimen geometries (a/W. Higher resulting values of J-integral for AISI 5120 than AISI 4140 can be noticed. Also, higher a/W ratios correspond to lower J-integral values of materials and vice versa. In addition to that, J-integral values obtained by using FE model of CT specimen give somewhat conservative results when compared with ones obtained by FE model of SENB specimen. Although this procedure differs from experimental analysis, results can be used a suitable fracture parameter value in fracture toughness assessment.DOI: http://dx.doi.org/10.5755/j01.ms.23.1.13823

  17. Simulation of Microdamage and Evaluation of Remaining Life of Steam Conduit Components from New-Generation Refractory Steel 10Kh9MF-Sh

    Science.gov (United States)

    Gladshtein, V. I.

    2018-03-01

    The effects of microdamage on the remaining life of high-temperature components of steam conduits from high-chromium steel 10Kh9MF-Sh and low-alloy steel 12Kh1M1F are compared. To simulate the microdamage, specimens with a circular notch and different relative diameters are fabricated. Specimens with a notch simulating the highest degree of microdamage and smooth specimens are tested for long-term strength. The coefficient of the remaining life of a conduit is computed for the range of relative damage presenting practical interest.

  18. Ultrasonic testing of canning tubes in stainless steel of the EL 4 reactor; Controle par ultrasons des tubes de gaine en acier inoxydable du reacteur EL 4

    Energy Technology Data Exchange (ETDEWEB)

    Prot, A; Monnier, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    From all the methods possible for controlling thin cans the one chosen, for numerous reasons, vas that making use of ultrasonic techniques. A method has been developed which should make it possible to carry out a rapid and efficient industrial control of canning tubes, The reasons for the choice of the ultrasonic method are given in detail, together with the principles of the method and the actual control parameters. In the present state of our research, it should be possible to control at least 50 000 tubes a year. Improvements brought about in the details of the control technique itself should make it possible to increase this rate considerably. (authors) [French] Parmi toutes les methodes possibles de controle des gaines minces, le procede retenu pour de multiples raisons a ete celui faisant appel a la technique des ultrasons. Une methode a ete mise au point qui doit permettre un controle industriel rapide et efficace des tubes de gaine. Sont exposes en detail, les raisons du choix de la methode par ultrasons, les principes de cette methode et les parametres du controle proprement dit. Dans l'etat actuel de nos etudes la cadence devrait permettre le controle de 50000 tubes par an au minimum. Des ameliorations de detail portant sur la technique de controle elle-meme, doivent permettre d'accelerer tres notablement cette cadence. (auteurs)

  19. Medium carbon steel deep drawing: A study on the evolution of mechanical properties, texture and simulations, from cold rolling to the end product

    Energy Technology Data Exchange (ETDEWEB)

    Plaut, Ronald L. [University of Sao Paulo, Sao Paulo (Brazil)], E-mail: rlplaut@usp.br; Padilha, Angelo F. [University of Sao Paulo, Sao Paulo (Brazil); Lima, N.B. [IPEN-CNEN/SP, Sao Paulo (Brazil); Herrera, Clara [Max-Planck-Institut fuer Eisenforschung (Germany); Filho, Antenor Ferreira [Industrial Director, Brasmetal Waelzholz S/A, Diadema (Brazil); Yoshimura, Leandro H. [CCS Consulting, Sao Paulo (Brazil)

    2009-01-15

    Medium carbon steels are mostly used for simple applications; nevertheless new applications have been developed for which good sheet formability is required. This class of steels has an inherent low formability. A medium carbon hot rolled SAE 1050 steel has been selected for this study. It has been cold rolled with reductions in the 7-80% range. Samples have been used to assess the cold work hardening curve. For samples with a 50 and 80% thickness reduction, an annealing heat treatment has been performed to obtain recrystallization. The material has been characterized in the 'as received', cold rolled and annealed conditions, using several methods: optical microscopy, X-ray diffraction (texture), Vickers hardness and tensile testing. The 50% cold rolled and recrystallized material has been further studied in terms of sheet metal formability and texture evolution during the actual stamping of a steel toecap that has been used to validate the finite element simulations.

  20. Welding simulation and fatigue assessment of tubular K-joints in high-strength steel

    International Nuclear Information System (INIS)

    Zamiri Akhlaghi, F.

    2014-01-01

    Application of newly developed high strength steel hollow sections is increasing in construction industry – especially for bridge structures – due to their satisfactory material properties and fabrication advantages. These sections allow for longer spans, more slender structures. Savings in weight and volume of material compared to traditional steel grades increase sustainability of construction and compensate for part of higher unit cost of material. Nevertheless, use of high strength steels cannot be promoted unless potential fatigue issues are properly addressed. Two fabrication methods are currently available for the planar Warren trusses made of circular hollow sections (CHS): welding the tubes together, or using cast steel nodes and connecting truss members to them by girth welds. Previous research on tubular bridge trusses indicates that the problematic fatigue cracking sites for the first fabrication method are located at weld toes in the gap region of the truss joints. For the second method, cracking occurs at the root of CHS–cast butt welds. Fatigue performance of these two methods were investigated by constant amplitude fatigue testing of two full scale trusses made of steel grade S690QH and with a geometry similar to previous S355J2H investigation. Fatigue lives of K-joints were in agreement with current recommended code values. For CHS–cast welded connections, no visible cracking was observed up to 2£10"6 cycles. Due to the effect of residual stresses, fatigue cracking was observed in compressive joints as well as tensile joints. Indeed, tensile welding residual stresses keep the crack open during all or part of the compressive load cycle. Their distribution and impact on fatigue life of tubular joints has not been fully investigated before for a complex detail such as Tubular K-joint made of high strength steel. Experimental and numerical methods were utilized for assessment of welding residual stresses. Neutron diffraction experiments were

  1. Erwartete Messung der Z Produktionsrate mit dem CMS Detektor und Simulation des Tracker Laser Alignment Systems

    CERN Document Server

    Thomas, Maarten

    2009-01-01

    The Large Hadron Collider is a two-ring, superconducting accelerator and collider which can provide both proton and heavy-ion beams. First collisions are foreseen for 2009. The Compact Muon System (CMS) detector will measure the particles created in the hadron collisions and can confirm the Standard Model by establishing the existence of the Higgs boson, but also search for new phenomena. In order to provide a robust and precise track reconstruction, which can already be used in the High-Level Trigger systems, the positions of the silicon sensors in the CMS tracker have to been known with an accuracy of O(100µm). Therefore the CMS tracker has been equipped with a dedicated alignment system. The Laser Alignment System (LAS) aligns the tracker subdetectors with respect to each other and can also monitor the stability of the sensor positions during data taking. This study describes the implementation of a realistic simulation of the LAS in the CMS software framework (CMSSW) as well as the analysis of the first ...

  2. Uniaxial low cycle fatigue behavior for pre-corroded 16MND5 bainitic steel in simulated pressurized water reactor environment

    Science.gov (United States)

    Chen, Xu; Ren, Bin; Yu, Dunji; Xu, Bin; Zhang, Zhe; Chen, Gang

    2018-06-01

    The effects of uniaxial tension properties and low cycle fatigue behavior of 16MND5 bainitic steel cylinder pre-corroded in simulated pressurized water reactor (PWR) were investigated by fatigue at room temperature in air and immersion test system, scanning electron microscopy (SEM), energy disperse spectroscopy (EDS). The experimental results indicated that the corrosion fatigue lives of 16MND5 specimen were significantly affected by the strain amplitude and simulated PWR environments. The compositions of corrosion products were complexly formed in simulated PWR environments. The porous corrosion surface of pre-corroded materials tended to generate pits as a result of promoting contact area to the fresh metal, which promoted crack initiation. For original materials, the fatigue cracks initiated at inclusions imbedded in the micro-cracks. Moreover, the simulated PWR environments degraded the mechanical properties and low cycle fatigue behavior of 16MND5 specimens remarkably. Pre-corrosion of 16MND5 specimen mainly affected the plastic term of the Coffin-Manson equation.

  3. Physical Simulation of a Duplex Stainless Steel Friction Stir Welding by the Numerical and Experimental Analysis of Hot Torsion Tests

    Science.gov (United States)

    da Fonseca, Eduardo Bertoni; Santos, Tiago Felipe Abreu; Button, Sergio Tonini; Ramirez, Antonio Jose

    2016-09-01

    Physical simulation of friction stir welding (FSW) by means of hot torsion tests was performed on UNS S32205 duplex stainless steel. A thermomechanical simulator Gleeble 3800® with a custom-built liquid nitrogen cooling system was employed to reproduce the thermal cycle measured during FSW and carry out the torsion tests. Microstructures were compared by means of light optical microscopy and electron backscatter diffraction. True strain and strain rate were calculated by numerical simulation of the torsion tests. Thermomechanically affected zone (TMAZ) was reproduced at peak temperature of 1303 K (1030 °C), rotational speeds of 52.4 rad s-1 (500 rpm) and 74.5 rad s-1 (750 rpm), and 0.5 to 0.75 revolutions, which represent strain rate between 10 and 16 s-1 and true strain between 0.5 and 0.8. Strong grain refinement, similar to the one observed in the stir zone (SZ), was attained at peak temperature of 1403 K (1130 °C), rotational speed of 74.5 rad s-1 (750 rpm), and 1.2 revolution, which represent strain rate of 19 s-1 and true strain of 1.3. Continuous dynamic recrystallization in ferrite and dynamic recrystallization in austenite were observed in the TMAZ simulation. At higher temperature, dynamic recovery of austenite was also observed.

  4. An Integrated Model for Computer Aided Reservoir Description : from Outcrop Study to Fluid Flow Simulations Un logiciel intégré pour une description des gisements assistée par ordinateur : de l'étude d'un affleurement aux simulations de l'écoulement des fluides

    Directory of Open Access Journals (Sweden)

    Guerillot D.

    2006-11-01

    Full Text Available An accurate understanding of the internal architecture of a reservoir is required to improve reservoir management for oil recovery. Geostatistical methods give an image of this architecture. The purpose of this paper is to show how this lithological description could be used for reservoir simulation. For this purpose, scale averaging problems must be solved for non-additive variables. A method giving a full effective permeability matrix is proposed. The integrated software described here starts from core analysis and lithologic logs to provide data for reservoir simulators. Each of the steps of this interactive and graphic system is explained here. Pour faire de bonnes prévisions de production pour un gisement pétrolifère, il est nécessaire de connaître précisément son architecture interne. Les méthodes géostatistiques donnent une représentation de cette architecture. L'objectif de cet article est de montrer une façon d'utiliser cette description lithologique pour la simulation des réservoirs. Il faut alors résoudre des problèmes de changement d'échelle pour les variables qui ne sont pas additives. On propose une méthode d'estimation de la perméabilité effective sous la forme d'une matrice pleine. Le logiciel intégré que l'on décrit part de l'analyse des carottes et des diagraphies en lithologies et fournit des données pour les simulateurs de gisement. On détaille ici chaque étape de ce système interactif graphique.

  5. Simulation of the hot flow behaviour of a medium carbon microalloyed steel. Part 1. Theoretical approach

    International Nuclear Information System (INIS)

    Cabrera, J.M.; Prado, J.M.

    1997-01-01

    The constitutive equations to model the hot flow behaviour of metallic materials in general, and of microalloyed steels in particular (see part 2 of this work) are established in this work. Special emphasis is done on the dynamic softening mechanisms, i.e., dynamic recovery and recrystallization phenomena. The equations developed are physic-based, not empirical, and the modelling allows an easy implementation in an analysis by numerical methods. The resulting equations are even able to predict the final grain size. (Author) 39 refs

  6. Factors Affecting Impact Toughness in Stabilized Intermediate Purity 21Cr Ferritic Stainless Steels and Their Simulated Heat-Affected Zones

    Science.gov (United States)

    Anttila, Severi; Alatarvas, Tuomas; Porter, David A.

    2017-12-01

    The correlation between simulated weld heat-affected zone microstructures and toughness parameters has been investigated in four intermediate purity 21Cr ferritic stainless steels stabilized with titanium and niobium either separately or in combination. Extensive Charpy V impact toughness testing was carried out followed by metallography including particle analysis using electron microscopy. The results confirmed that the grain size and the number density of particle clusters rich in titanium nitride and carbide with an equivalent circular diameter of 2 µm or more are statistically the most critical factors influencing the ductile-to-brittle transition temperature. Other inclusions and particle clusters, as well as grain boundary precipitates, are shown to be relatively harmless. Stabilization with niobium avoids large titanium-rich inclusions and also suppresses excessive grain growth in the heat-affected zone when reasonable heat inputs are used. Thus, in order to maximize the limited heat-affected zone impact toughness of 21Cr ferritic stainless steels containing 380 to 450 mass ppm of interstitials, the stabilization should be either titanium free or the levels of titanium and nitrogen should be moderated.

  7. Synergistic Inhibition of Carbon Steel Corrosion by Inhibitor-Blends in Chloride-Containing Simulated Cooling Water

    Energy Technology Data Exchange (ETDEWEB)

    Shaban, Abdul; Felhosi, Ilona [Hungarian Academy of Sciences, Budapest (Hungary); Vastag, Gyongyi [University of Novi Sad, Novi Sad (Serbia)

    2017-06-15

    The objective of this work was to develop efficient synergistic inhibitor combinations comprising sodium nitrite (NaNO{sub 2}) and an inhibitor-blend code named (SN-50), keeping in view of their application in industrial cooling water systems. The electrochemical characteristics of the carbon steel working electrode in simulated cooling water (SCW), without and with the addition of different combinations of the inhibitors, were investigated using electrochemical impedance spectroscopy (EIS), open circuit potential (OCP). The electrode surface changes were followed by visual characterization methods. It was demonstrated in this study that all the combinations of the inhibitors exhibited synergistic benefit and higher inhibition efficiencies than did either of the individual inhibitors. The addition of SN-50 inhibitor to the SCW shifted the OCP to more anodic values and increased the polarization resistance (R{sub p}) values of carbon steel at all applied concentrations. The higher the applied sodium nitrite concentration (in the protection concentration range), the higher the obtained R{sub p} values and the inhibition efficiency improved by increasing the inhibitor concentration.

  8. The precipitation response of 20%-cold-worked type 316 stainless steel to simulated fusion irradiation

    International Nuclear Information System (INIS)

    Maziasz, P.J.

    1979-01-01

    The precipitation response of 20%-cold-worked type 316 stainless steel has been examined after irradiation in HFIR at 380-600 0 C, after irradiation in EBR-II at 500 0 C, and after thermal aging at 600 to 750 0 C. Eta phase forms during exposure to all environments. It constitutes a major portion of the precipitation response, and is rich in Ni, Si and Mo relative to M 23 C 6 after thermal aging. It is not normally reported in 20%-cold-worked type 316 stainless steel. The eta, M 23 C 6 , Laves, sigma, and chi precipitate phases appear at similar temperatures after HFIR, EBR-II, or thermal exposure. There are, however, some differences in relative amounts, size, and distribution of phases among the various environments. Eta phase is the only carbide-type phase observed after irradiation in HFIR from 380-550 0 C. The large cavities associated with it at 380 0 C contribute significantly to swelling. Re-solution of fine M 23 C 6 , eta, and Laves particles and re-precipitation of massive particles of sigma, M 23 C 6 and chi are observed after recrystallization in HFIR. (orig.)

  9. Modelisation et simulation de pyrolyse de pneus usages dans des reacteurs de laboratoire et industriel

    Science.gov (United States)

    Lanteigne, Jean-Remi

    decomposition kinetics of pyrolysables. The simulation with data obtained in industrial operation showed the robustness of the model to predict with accuracy in transient regime, tires pyrolysis, with the help of model parameters obtained at laboratory scale, namely in regards of the trigger of production, the residence time of tires (dynamic production) and the amount of oil produced (cumulative yield). It is a novel way to model pyrolysis that could be extrapolated to new waste materials. The second objective of this doctoral research was to determine the evolution of specific tires specific heat during pyrolysis and the enthalpy of pyrolysis. The origin of this objective comes from a primary contradiction. With few exceptions, it is acknowledged that organic materials pyrolysis is globally an endothermic phenomenon. At the opposite, all experiments led with laboratory apparatuses such as DSC (Differential Scanning Calorimetry) showed exothermic peaks during dynamic experiments (constant heating rate). It has been confirmed by results obtained at the industrial scale, where no sign of exothermicity has been observed. The Hess Law has also confirmed these results, that globally, pyrolysis is indeed a completely endothermic process. An accurate energy balance is required to predict mass temperature during pyrolysis, this parameter being unbindable from kinetics. An advanced investigation of char first allowed demonstrating that specific heat of solids during pyrolysis decreases with increasing temperature until the weight loss peak is reached, around 400°C, and then starts increasing again. This observation, combined with the fact that the sample loses weight during pyrolysis is considered as the major cause of the apparition of an exothermic peak in laboratory scale experiments. That is, the control system of these apparatuses generates a bias and an unavoidable overheat of the samples producing this exothermic behavior. It would thus be an artifact. On the base of new data

  10. Large Eddy Simulations of Electromagnetic Braking Effects on Argon Bubble Transport and Capture in a Steel Continuous Casting Mold

    Science.gov (United States)

    Jin, Kai; Vanka, Surya P.; Thomas, Brian G.

    2018-06-01

    In continuous casting of steel, argon gas is often injected to prevent clogging of the nozzle, but the bubbles affect the flow pattern, and may become entrapped to form defects in the final product. Further, an electromagnetic field is frequently applied to induce a braking effect on the flow field and modify the inclusion transport. In this study, a previously validated GPU-based in-house code CUFLOW is used to investigate the effect of electromagnetic braking on turbulent flow, bubble transport, and capture. Well-resolved large eddy simulations are combined with two-way coupled Lagrangian computations of the bubbles. The drag coefficient on the bubbles is modified to account for the effects of the magnetic field. The distribution of the argon bubbles, capture, and escape rates, are presented and compared with and without the magnetic field. The bubble capture patterns are also compared with results of a previous RANS model as well as with plant measurements.

  11. Experimental and Simulation Analysis of Hot Isostatic Pressing of Gas Atomized Stainless Steel 316L Powder Compacts

    International Nuclear Information System (INIS)

    Lin, Dongguo; Park, Seong Jin; Ha, Sangyul; Shin, Youngho; Park, Dong Yong; Chung, Sung Taek; Bollina, Ravi; See, Seongkyu

    2016-01-01

    In this work, both experimental and numerical studies were conducted to investigate the densification behavior of stainless steel 316L (STS 316L) powders during hot isostatic pressing (HIP), and to characterize the mechanical properties of HIPed specimens. The HIP experiments were conducted with gas atomized STS 316L powders with spherical particle shapes under controlled pressure and temperature conditions. The mechanical properties of HIPed samples were determined based on a series of tensile tests, and the results were compared to a reference STS 316L sample prepared by the conventional process, i.e., extrusion and annealing process. Corresponding microstructures before and after tensile tests were observed using scanning electron microscopy and their relationships to the mechanical properties were addressed. Furthermore, a finite element simulation based on the power-law creep model was carried out to predict the density distribution and overall shape change of the STS316L powder compact during HIP process, which agreed well with the experimental results.

  12. Simulation and analysis of the residual stresses in functionally graded Al2O3 coatings on CLAM steel

    International Nuclear Information System (INIS)

    Yan Zilin; Huang Qunying; Song Yong; Guo Zhihui; Wu Yican

    2008-01-01

    Alumina coatings on CLAM steel substrate are proposed to serve as tritium, corrosion and electric insulation barriers in the design of Dual Functional Lithium Lead Test Blanket Module (DFLL-TBM) in China in the frame of ITER. In order to avoid the crack failure due to thermal expansion mismatch of the coating and the substrate, the functionally graded materials (FGM) concept was adopted. In this paper, the residual thermal stresses in the coatings were calculated with the commercial software ANSYS. It is recommended that the compositional factor, numbers of the gradient interlayers and the thickness of the FGM zone are p=0.8, N=8, H=0.6 mm, respectively, according to the simulation results. These results could be helpful and theoretical guidance to the preparation and optimization of the coatings in the future. (authors)

  13. Cracking behavior of reinforced concrete beams: experiment and simulations on the numerical influence of the steel-concrete bond

    International Nuclear Information System (INIS)

    Jason, L.; Torre-Casanova, A.; Pinelli, X.; Davenne, L.

    2013-01-01

    Experimental and numerical results are provided in this contribution to study the global and cracking behaviors of two reinforced concrete beams subjected to four point bending. Experimentally, the use of image correlation technique enables to obtain precise information concerning the cracking properties (spacing, cumulated, maximum and mean values of the opening). Numerically, two simulations are compared taking into account a bond model between steel and concrete or supposing a perfect relation between the two materials. In both cases, a good agreement is achieved between numerical and experimental results even if the introduction of the bond effects has a direct influence during the development of the cracks (better agreement during the 'active' cracking phase). (authors)

  14. Experimental and Simulation Analysis of Hot Isostatic Pressing of Gas Atomized Stainless Steel 316L Powder Compacts

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Dongguo; Park, Seong Jin [Pohang University of Science and Technology, Pohang (Korea, Republic of); Ha, Sangyul [Samsung Electro-Mechanics, Suwon (Korea, Republic of); Shin, Youngho [Doosan Heavy Industries and Construction Co., Ltd., Changwon (Korea, Republic of); Park, Dong Yong [Korea Institute of Energy Research, Daejeon (Korea, Republic of); Chung, Sung Taek [CetaTech Inc., Sacheon (Korea, Republic of); Bollina, Ravi [Bahadurpally Jeedimetla, Hyderabad (India); See, Seongkyu [POSCO, Pohang (Korea, Republic of)

    2016-10-15

    In this work, both experimental and numerical studies were conducted to investigate the densification behavior of stainless steel 316L (STS 316L) powders during hot isostatic pressing (HIP), and to characterize the mechanical properties of HIPed specimens. The HIP experiments were conducted with gas atomized STS 316L powders with spherical particle shapes under controlled pressure and temperature conditions. The mechanical properties of HIPed samples were determined based on a series of tensile tests, and the results were compared to a reference STS 316L sample prepared by the conventional process, i.e., extrusion and annealing process. Corresponding microstructures before and after tensile tests were observed using scanning electron microscopy and their relationships to the mechanical properties were addressed. Furthermore, a finite element simulation based on the power-law creep model was carried out to predict the density distribution and overall shape change of the STS316L powder compact during HIP process, which agreed well with the experimental results.

  15. 'In-beam' simulation of high temperature helium embrittlement of DIN 1.4970 austenitic stainless steel

    International Nuclear Information System (INIS)

    Schroeder, H.; Batfalsky, P.

    1982-01-01

    This work describes a facility for high temperature creep rupture tests during homogeneous helium implantation. This 'in-beam' creep testing facility is used to simulate helium embrittlement effects which will be very important for first wall materials of future fusion reactors operated at high temperatures. First results for DIN 1.4970 austenitic stainless steel clearly demonstrate differences between samples 'in-beam' tested at 1073 K and those creep tested at the same temperature after room temperature helium implantation. The specimens ruptured 'in-beam' have much shorter lifetimes and lower ductility than the specimens tested after room temperature implantation. There are also differences in the microstructures, concerning helium bubble sizes and densities in matrix and grain boundaries. These microstructural differences may be a key for the understanding of the more severe helium embrittlement effects 'in-beam' as compared to creep tests performed after room temperature implantation. (orig.)

  16. Corrosion of low Si-alloyed steels in aqueous solution at 90 deg. C. Inhibitive action of silicates; Corrosion d'aciers faiblement allies au silicium en solution aqueuse a 90 deg. C. Action inhibitrice des silicates

    Energy Technology Data Exchange (ETDEWEB)

    Giordana, S

    2002-02-01

    Low-Si alloyed steels, with Si content ranging from 0.25 to 3.2 wt%, as potential candidate materials for high-level nuclear waste disposal containers, have been studied four the point of view of their corrosion behaviour at 90 deg C in an aqueous solution simulating groundwater (0.1 M NaCl borate-buffered solution with a pH of 8.5) both in reducing and in aerated conditions. The influence of silicate addition to the solution is examined so as to represent the silicon of groundwater, coming from the clay dissolution. When no silicate was added to the solution, silicon as an alloying element was proved to degrade in the first moments the steel ability to passivate. For longer immersion times, protective effects developed most efficiently on the steel containing 3.2 wt% silicon both in reducing an in aerating conditions, Infrared spectroscopy, EDSX, XRD and Raman microprobe were applied to characterise the oxide layer composition, which was found to be a mixture of magnetite and maghemite. In the presence of silicate in the solution, clay-like iron silicates appeared in the corrosion layer. Electrochemical tests results show that adding silicate into solution resulted in increasing the steel ability to passivate. In the short term, the inhibiting effect of silicate was confirmed by mass loss tests, but the tendency was inverse in the long term. Silicate iron layers were eventually less protective than the magnetite layers formed in the absence of silicate. (author)

  17. Steel, hard metal and diamonds. The history of drilling blast holes in mining and tunneling; Stahl, Hartmetall und Diamanten. Zur Geschichte des Sprenglochbohrens im Berg- und Tunnelbau

    Energy Technology Data Exchange (ETDEWEB)

    Feistkorn, E. [Inst. fuer Vortrieb und Gewinnung, DMT-Gesellschaft fuer Forschung und Pruefung mbH, Essen (Germany)

    1997-12-31

    Beginning of the blasting technique in mining and tunneling during the 17th century required drilling holes to take the explosive. Following the use of hammer and wedge, drilling was done over a long period of time by hand with mallet and drillsteel. Continuously, during the 19th century the handwork was replaced by drilling machines. Technically, the evolution of drilling equipment is marked by electrohydraulic control and automatization with the assistance of microelectronics. Regarding the material, the introduction of hard metal and - in addition for rotary drilling - the development of synthetic diamond material are the main features. (orig.) [Deutsch] Mit der Einfuehrung der Sprengtechnik im Bergbau und Tunnelbau im 17. Jahrhundert mussten verfahrensbedingt Bohrloecher zur Aufnahme des Sprengstoffes hergestellt werden. In Anlehnung an die Arbeit mit Schlaegel und Eisen erfolgte dies lange Zeit manuell mit dem Bohrfaeustel und Stahlbohrern. Die Handarbeit wurde waehrend der 2. Haelfte des 19. Jahrhunderts kontinuierlich durch Bohrmaschinen verdraengt. Maschinentechnisch ist die weitere Entwicklung durch elektrohydraulische Steuerungen und die Automatisierung der Bohrgeraete mit Hilfe der Mikroelektronik gekennzeichnet. Materialtechnisch stellen die Einfuehrung des Hartmetalls und beim drehenden Bohren zusaetzlich die Entwicklung synthetischer Diamantwerkstoffe die herausragenden Marksteine dar. (orig.)

  18. Simulations of the Penetration of 6061-T6511 Aluminum Targets by Spherical-Nosed VAR 4340 Steel Projectiles

    Energy Technology Data Exchange (ETDEWEB)

    Tabbara, M.R.; Warren, T.L.

    1998-10-21

    In certain penetration events it is proposed that the primary mode of deformation of the target can be approximated by known analytical expressions. In the context of an analysis code, this approximation eliminates the need for discretizing the target as well as the need for a contact algorithm. Thus, this method substantially reduces the computer time and memory requirements. In this paper a forcing function which is derived from a spherical-cavity expansion (SCE) analysis has been implemented in a transient dynamic finite element code. This irnplementation is capable of computing the structural and component responses of a projectile due to a three dimensional penetration event. Simulations are presented for 7.1 l-mm-diameter, 74.7-mm-long, spherical-nose, vacuum- arc-remelted (VAR) 4340 steel projectiles that penetrate 6061-T6511 aluminum targets. Final projectile configurations obtained from the simulations are compared with post-test radiographs obtained from the corresponding experiments. It is shown that the simulations accurately predict the permanent projectile deformation for three dimensional loadings due to incident pitch and yaw over a wide range of striking velocities.

  19. Electrochemical impedance spectrometry using 316L steel, hastelloy, maraging, Inconel 600, Elgiloy, carbon steel, TiN and NiCr. Simulation in tritiated water. 2 volumes; Spectrometrie d`impedance electrochimique sur acier 316L, hastelloy, maraging inconel 600, elgiloy, acier au carbone, TiN, NiCr. Simulations en eau tritiee. 2 volumes

    Energy Technology Data Exchange (ETDEWEB)

    Bellanger, G.

    1994-03-01

    Polarization and electrochemical impedance spectrometry curves are presented and discussed. These curves make it possible to ascertain the corrosion domains and to compare the slow and fast kinetics (voltammetry) of different stainless steel alloys. These corrosion kinetics, the actual or simulated tritiated water redox potentials, and the corrosion potentials provide a classification of the steels studied here: 316L, Hastelloy, Maraging, Inconel 600, Elgiloy, carbon steel and TiN and NiCr deposits. From the results it can be concluded that Hastelloy and Elgiloy have the best corrosion resistance. (author). 49 refs., 695 figs., tabs.

  20. The effect of simulated inflammatory conditions on the surface properties of titanium and stainless steel and their importance as biomaterials

    International Nuclear Information System (INIS)

    Fonseca-García, Abril; Pérez-Alvarez, J.; Barrera, C.C.; Medina, J.C.; Almaguer-Flores, A.; Sánchez, R. Basurto

    2016-01-01

    This work compares the surface modifications induced by the immersion in solutions that simulate inflammatory conditions of pure titanium (cpTi) and medical grade stainless steel (SS). The inflammatory conditions were simulated using a mixture of Hartman solution and 50 mM of hydrogen peroxide (H_2O_2) at pH = 5.2. The samples were immersed by 7 days refreshing the solution every day to keep the reactivity of the H_2O_2. The surface characteristics that were investigated were: elemental composition by X-ray photoelectron spectroscopy (XPS); topography by atomic force microscopy (AFM) and profilometry; wettability and surface energy by sessile drop contact angle and point of zero charge by titration. Moreover, the variations in the electrochemical response were evaluated by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP) performed before and after the treatment using the Hartman solution as the electrolyte. The XPS results indicated that for both metallic samples, oxidation of the surface was promoted and/or the oxide layer was thicker after the immersion. The roughness and the solid-liquid surface energy were increased; the samples showed a more hydrophilic character after the treatment. However, the surface energy of the solid estimated using the Van Oss–Chaudhury–Good approach showed different trends between the cpTi and the SS surfaces; the polar component decreased for cpTi, while it increased for SS. Finally, the electrochemical results indicated that the corrosion resistance (R_c_o_r) and the pore resistance (R_p_o) significantly decreased for cpTi, while both resistances were not significantly different for the SS. This is indicative of a higher dissolution of the cpTi compared to SS and the lower R_p_o means that the species are easily transported through the surface layer, which can be explained in terms of the formation of a porous TiO_x layer, not observed on the SS. The cpTi surface

  1. Investigation of irradiation induced inter-granular stress corrosion cracking susceptibility on austenitic stainless steels for PWR by simulated radiation induced segregation materials

    Energy Technology Data Exchange (ETDEWEB)

    Yonezawa, Toshio; Fujimoto, Koji; Kanasaki, Hiroshi; Iwamura, Toshihiko [Mitsubishi Heavy Industries Ltd., Takasago R and D Center, Takasago, Hyogo (Japan); Nakada, Shizuo; Ajiki, Kazuhide [Mitsubishi Heavy Industries Ltd., Kobe Shipyard and Machinery Works, Kobe, Hyogo (Japan); Urata, Sigeru [General Office of Nuclear and Fossil Power Production, Kansai Electric Power Co., Inc., Osaka (Japan)

    2000-07-01

    An Irradiation Assisted Stress Corrosion Cracking (IASCC) has not been found in Pressurized Water Reactors (PWRs). However, the authors have investigated on the possibility of IASCC so as to be able to estimate the degradation of PWR plants up to the end of their lifetime. In this study, the authors melted the test alloys whose bulk compositions simulated the grain boundary compositions of irradiated Type 304 and Type 316 CW stainless steels. Low chromium, high nickel and silicon (12%Cr-28%Ni-3%Si) steel showed high susceptibility to PWSCC (Primary Water Stress Corrosion Cracking) by SSRT (Slow Strain Rate Tensile) test in simulated PWR primary water. PWSCC susceptibility of the test steels increases with a decrease of chromium content and a increase of nickel and silicon contents. The aged test steel included coherent M{sub 23}C{sub 6} carbides with matrices at the grain boundaries showed low PWSCC susceptibility. This tendency is in very good agreement with that of the PWSCC susceptibility of nickel based alloys X-750 and 690. From these results, if there is the possibility of IASCC for austenitic stainless steels in PWRs, in the future, the IASCC shall be caused by the PWSCC as a result of irradiation induced grain boundary segregation. (author)

  2. Microstructural characteristics and toughness of the simulated coarse grained heat affected zone of high strength low carbon bainitic steel

    International Nuclear Information System (INIS)

    Lan Liangyun; Qiu Chunlin; Zhao Dewen; Gao Xiuhua; Du Linxiu

    2011-01-01

    Highlights: → Total toughness can be separated into crack initiation energy and crack propagation energy. → Small effective grain size of lath martensite can improve the crack propagation energy. → MA constituent is mainly responsible for the low toughness of coarse bainite specimens. → High angle packet boundary in coarser bainite has few contributions to improving crack propagation energy. - Abstract: The correlation of microstructural characteristics and toughness of the simulated coarse grained heat affected zone (CGHAZ) of low carbon bainitic steel was investigated in this study. The toughness of simulated specimens was examined by using an instrumented Charpy impact tester after the simulation welding test was conducted with different cooling times. Microstructure observation and crystallographic feature analysis were conducted by means of optical microscope and scanning electron microscope equipped with electron back scattered diffraction (EBSD) system, respectively. The main microstructure of simulated specimen changes from lath martensite to coarse bainite with the increase in cooling time. The deterioration of its toughness occurs when the cooling time ranges from 10 to 50 s compared with base metal toughness, and the toughness becomes even worse when the cooling time increases to 90 s or more. The MA (martensite-austenite) constituent is primary responsible for the low toughness of simulated CGHAZ with high values of cooling time because the large MA constituent reduces the crack initiation energy significantly. For crack propagation energy, the small effective grain size of lath martensite plays an important role in improving the crack propagation energy. By contrast, high misorientation packet boundary in coarse bainite seems to have few contributions to the improvement of the toughness because cleavage fracture micromechanism of coarse bainite is mainly controlled by crack initiation.

  3. Microstructural characteristics and toughness of the simulated coarse grained heat affected zone of high strength low carbon bainitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Lan Liangyun, E-mail: lly.liangyun@gmail.com [State Key Laboratory of Rolling Technology and Automation, Northeastern University, Shenyang 110819 (China); Qiu Chunlin; Zhao Dewen; Gao Xiuhua; Du Linxiu [State Key Laboratory of Rolling Technology and Automation, Northeastern University, Shenyang 110819 (China)

    2011-11-25

    Highlights: {yields} Total toughness can be separated into crack initiation energy and crack propagation energy. {yields} Small effective grain size of lath martensite can improve the crack propagation energy. {yields} MA constituent is mainly responsible for the low toughness of coarse bainite specimens. {yields} High angle packet boundary in coarser bainite has few contributions to improving crack propagation energy. - Abstract: The correlation of microstructural characteristics and toughness of the simulated coarse grained heat affected zone (CGHAZ) of low carbon bainitic steel was investigated in this study. The toughness of simulated specimens was examined by using an instrumented Charpy impact tester after the simulation welding test was conducted with different cooling times. Microstructure observation and crystallographic feature analysis were conducted by means of optical microscope and scanning electron microscope equipped with electron back scattered diffraction (EBSD) system, respectively. The main microstructure of simulated specimen changes from lath martensite to coarse bainite with the increase in cooling time. The deterioration of its toughness occurs when the cooling time ranges from 10 to 50 s compared with base metal toughness, and the toughness becomes even worse when the cooling time increases to 90 s or more. The MA (martensite-austenite) constituent is primary responsible for the low toughness of simulated CGHAZ with high values of cooling time because the large MA constituent reduces the crack initiation energy significantly. For crack propagation energy, the small effective grain size of lath martensite plays an important role in improving the crack propagation energy. By contrast, high misorientation packet boundary in coarse bainite seems to have few contributions to the improvement of the toughness because cleavage fracture micromechanism of coarse bainite is mainly controlled by crack initiation.

  4. Simulation of land use evolution by discrete events method: Application to “la chaîne des puys” from XV to XVIII Century

    OpenAIRE

    Y. Michelin; C. Poix

    1998-01-01

    By using a discrete event method, simulation of land use evolution has been applied to a landscape model of “la ChaÎne des Puys” (French Massif Central) during along period (XV–XVIII centuries). The indications concerning the evolution of land use are in conformity with the observation of actual situations but the dynamic changes are faster than in actual facts. In spite of limitations due to necessary simplifications, it is now established that the discrete event method is efficient to simu...

  5. A macroscopic model to simulate the mechanically induced martensitic transformation in metastable austenitic stainless steels

    International Nuclear Information System (INIS)

    Perdahcıoğlu, E.S.; Geijselaers, H.J.M.

    2012-01-01

    Mechanically induced martensitic transformation and the associated transformation plasticity phenomena in austenitic stainless steels are studied. The mechanisms responsible for the transformation are investigated and put into perspective based on experimental evidence. The stress and strain partitioning into the austenite and martensite phases are formulated using a mean-field homogenization approach. At this intermediate length-scale the average stress in the austenite phase is computed and utilized to compute the mechanical driving force resolved in the material. The amount of transformation and the transformation plasticity is derived as a function of the driving force. The mechanical response of the material is obtained by combining the homogenization and the transformation models. The model is verified by mechanical tests under biaxial loading conditions during which different transformation rates are observed. As a final verification of the model, a bending test is used which manifests the stress-state dependency of the transformation.

  6. Simulation of the hot flow behaviour of a medium carbon microalloyed steel

    International Nuclear Information System (INIS)

    Cabrera, J.M.; Al Omar, A.; Prado, J.M.

    1997-01-01

    According to the part 1 of this work the constitutive equations of the hot flow behaviour of a commercial microalloyed steel have been obtained. For this purpose, the uniaxial hot compression tests described in the part 2 were employed. Tests were carried out over a range of 5 orders of magnitude in strain rate and 300 degree centigree of temperature. Experimental results are compared with the theoretical model introduced in the first part of this study. It is concluded that deviations between experimental and theoretical curves are lower than 10%. It is shown that the classical hyperbolic sine constitutive equation described accurately the experimental behaviour provided that stresses are normalized by the Young's modulus and strain rates by the self-diffusion coefficient. An internal stress must also be introduced in the latter equation when the initial grain size is fine enough. (Author) 24 refs

  7. Numerical and experimental simulation of mechanical and microstructural transformations in Batch annealing steels

    International Nuclear Information System (INIS)

    Monsalve, A.; Artigas, A.; Celentano, D.; Melendez, F.

    2004-01-01

    The heating and cooling curves during batch annealing process of low carbon steel have been modeled using the finite element technique. This has allowed to predict the transient thermal profile for every point of the annealed coils, particularly for the hottest and coldest ones. Through experimental measurements, the results have been adequately validated since a good agreement has been found between experimental values and those predicted by the model. Moreover, an Avrami recrystallization model. Moreover, and Avrami recrystallization model has been coupled to this thermal balance computation. Interrupted annealing experiments have been made by measuring the recrystallized fraction on the extreme points of the coil foe different times. These data gave the possibility to validate the developed recrystallization model through a reasonably good numerical-experimental fittings. (Author) 6 refs

  8. Effect of nitrogen in austenitic stainless steel on deformation behavior and stress corrosion cracking susceptibility in BWR simulated environment

    International Nuclear Information System (INIS)

    Roychowdhury, S.; Kain, V.; Dey, G.K.

    2012-01-01

    Intergranular stress corrosion cracking (IGSCC) of austenitic stainless steel (SS) components in boiling water reactor (BWR has been a serious issue and is generic in nature. Initial cracking incidences were attributed to weld induced sensitisation and low temperature sensitisation which was mitigated by the use of low carbon grade of SS and molybdenum and nitrogen containing nuclear grade SS. However, IGSCC has occurred in these SS in the non-sensitised condition which was attributed to residual weld induced strain. Strain hardening in SS has been identified as a major cause for enhanced IGSCC susceptibility in BWR environment. Nitrogen in SS has a significant effect on the strain hardening characteristics and has potential to affect the IGSCC susceptibility in BWR environment. Type 304LN stainless steel is a candidate material for use in future reactors with long design life like the Advanced Heavy Water Reactor (AHWR), in which the operating conditions are similar to BWR. This study reports the effect of nitrogen in type 304LN stainless steel on the strain hardening behaviour and deformation characteristics and its effect on the IGSCC susceptibility in BWR/AHWR environment. Two heats of type 304LN stainless steel were used containing different levels of nitrogen, 0.08 and 0.16 wt % (SS alloys A and B, respectively). Both the SS was strain hardened by cross rolling at 200℃ to simulate the strain hardened regions having higher IGSCC susceptibility in BWRs. Tensile testing was done at both room temperature and 288℃(temperature simulating operating BWR conditions) and the effect of nitrogen on the tensile properties were established. Tensile testing was done at strain rates similar to the crack tip strain rates associated with a growing IGSCC in SS. Detailed transmission electron microscopic (TEM) studies were done to establish the effect of nitrogen on the deformation modes. Results indicated twinning was the major mode of deformation during cross rolling while

  9. L'evolution thermique de la matière organique des sédiments : applications d'une simulation mathématique. Potentiel pétrolier des bassins sédimentaires de reconstitution de l'histoire thermique des sédiments Thermal Evolution of Organic Matter in Sediments : Application of a Mathematical Simulation. Petrleum Potential of Sedimentary Basins and Reconstructing the Thermal History of Sediments

    Directory of Open Access Journals (Sweden)

    Tissot B.

    2006-11-01

    Full Text Available Au moyen d'un modèle mathématique, on simule la dégradation thermique de la matière organique des sédiments. Les applications possibles de ce modèle concernent la recherche des zones favorables pour la prospection de l'huile ou du gaz, la détermination de l'époque de formation des hydrocarbures pour la comparer avec l'âge des pièges et celui des couvertures, l'évaluation des réserves ultimes d'un bassin, ainsi que la pyrogénation des schistes bitumineux. Le type de matière organique est représenté dans le modèle par un jeu de constantes qui sont déterminées par des essais de laboratoire; on discute en particulier la distribution des énergies d'activation et sa signification en rapport avec la composition du kérogène. Les autres données nécessaires sont la reconstitution géologique de l'enfouissement et le gradient géothermique. La reconstitution de la géothermie ancienne pose un problème particulier. En associant la mesure de la réflectance de la vitrinite et la loi d'enfouissement, on peut, au moyen d'un modèle d'évolution de la vitrinite, rétablir dans la plupart des cas l'histoire thermique de la matière organique. Ce résultat présente certes un grand intérêt pour l'exploration pétrolière, mais son champ d'application dépasse largement ce domaine et s'étend aux problèmes de géologie générale géothermie, diagenèse des sédiments, tectonique globale, etc. A mathematical model is used to simulate the thermal degradation of the organic matter in sediments. The possible applications of this model have to do with the seorch for favorable ail or gas prospection zones, determining the period when hydrocarbons were formed so as to compare it with the age of traps and caprocks, and estimating the ultimate reserves of a basin a well as the pyrogenation of ail shales. The type of organic matter is represented in the model by a set of constants that are determined by laboratory tests. This article in

  10. Computer simulations of austenite decomposition of microalloyed 700 MPa steel during cooling

    Science.gov (United States)

    Pohjonen, Aarne; Paananen, Joni; Mourujärvi, Juho; Manninen, Timo; Larkiola, Jari; Porter, David

    2018-05-01

    We present computer simulations of austenite decomposition to ferrite and bainite during cooling. The phase transformation model is based on Johnson-Mehl-Avrami-Kolmogorov type equations. The model is parameterized by numerical fitting to continuous cooling data obtained with Gleeble thermo-mechanical simulator and it can be used for calculation of the transformation behavior occurring during cooling along any cooling path. The phase transformation model has been coupled with heat conduction simulations. The model includes separate parameters to account for the incubation stage and for the kinetics after the transformation has started. The incubation time is calculated with inversion of the CCT transformation start time. For heat conduction simulations we employed our own parallelized 2-dimensional finite difference code. In addition, the transformation model was also implemented as a subroutine in commercial finite-element software Abaqus which allows for the use of the model in various engineering applications.

  11. Some elevated temperature tensile and strain-controlled fatigue properties for a 9%Cr1Mo steel heat treated to simulate thick section material

    International Nuclear Information System (INIS)

    Sanderson, S.J.; Jacques, S.

    Current interest has been expressed in the usage of thick section 9%Cr1%Mo steel, particularly for UK Commercial Demonstration Fast Reactor (CDFR) steam generator tubeplates. This paper presents the results of some preliminary mechanical property test work on a single cast of the steel, heat treated to simulate heavy ruling sections encompassing thicknesses likely to be met in the CDFR context. The microstructures of the simulated thick section material were found to remain predominantly as tempered martensite even at the slowest transformation cooling rates used (50 deg. C/h). The effect of microstructure is reflected in the elevated temperature proof stress, tensile strength and strain-controlled fatigue endurance which were found to be comparable with the properties established for thin section normalised and tempered 9%Cr1%Mo steel. These results are extremely encouraging and, taken in conjunction with the results from other simulation work on this material, further demonstrate the potential of thick section 9%Cr1%Mo steel. (author)

  12. Dynamic Simulation as a tool to improve the efficiency of Energy Sytems. Applications in the Steel Industry

    Directory of Open Access Journals (Sweden)

    Kitzber R.

    2012-10-01

    Full Text Available To answer the need in reducing the amount and costs of the energetic consumptions in large industries, improvement methods mostly based on stationary considerations are being used today. It is difficult with such approaches to consider potentials hidden in time dependent effects. The batch operated processes of an Integrated Iron and Steel Plant (IISP typically show time dependent behaviour. Therefore, dynamic considerations are used in this paper to increase the efficiency of energy systems (steam and hot water networks in a European IISP. This allows the consideration of potential improvements not only through modifications of the process design and operating conditions but also through optimized control parameters, and enhancement of the transient operation procedures. This paper describes an improvement procedure for the considered energy systems. The physical modelling of all main components (sources, network piping, valves and control devices, is carried out with the simulation program APROS. The potential use of the physical dynamic models is then illustrated by a practical example, which deals with the operating conditions enhancement of a steam turbine. Finally, the application range of the developed simulation models is discussed. Especially, their further utilization for the implementation of model predictive control is outlined.

  13. The compatibility of chromium-aluminium steels with high pressure carbon dioxid at intermediate- temperatures; Compatibilite des aciers au chrome-aluminium avec le gaz carbonique sous pression aux temperatures moyennes

    Energy Technology Data Exchange (ETDEWEB)

    Leclercq, D; Loriers, H; David, R; Darras, E [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    With a view to their use in the exchangers of nuclear reactors of the graphite-gas or heavy water-gas types, the behaviour of chromium-aluminium steels containing up to 7 per cent chromium and 1.5 per cent aluminium has been studied in the presence of high-pressure carbon dioxide at temperatures of between 400 and 700 deg. C. The two most interesting grades of steel (2 per cent Cr - 0.35 per cent Al - 0.35 per cent Mo and 7 per cent Cr - 1.5 per cent Al - 0.6 per cent Si) are still compatible with carbon dioxide up to 550 and 600 deg. C respectively. A hot dip aluminised coating considerably increases resistance to oxidation of the first grade and should make possible its use up to temperatures of at least 600 deg. C. (authors) [French] Dans l'optique de leur emploi dans les echangeurs de reacteurs nucleaires des filieres graphite-gaz ou eau lourde-gaz, le comportement en presence de gaz carbonique sous pression d'aciers au chrome-aluminium, contenant jusqu'a 7 pour cent de chrome et 1,5 pour cent d'aluminium a ete etudie entre 400 et 700 deg. C. Les deux nuances les plus interessantes (2 pour cent Cr - 0,35 pour cent Al - 0,35 pour cent Mo et 7 pour cent Cr - 1,5 pour cent Al - 0,6 pour cent Si) restent compatibles avec le gaz carbonique jusqu'a 550 et 600 deg. C respectivement. Un revetement d'aluminium, effectue par immersion dans un bain fondu, ameliore notablement la resistance a l'oxydation de la premiere et doit permettre son empioi jusqu'a 600 deg. C au moins. (auteurs)

  14. Sub-impacts of simply supported beam struck by steel sphere—part II: Numerical simulations

    Directory of Open Access Journals (Sweden)

    Xiaoli Qi

    2016-12-01

    Full Text Available This part of the article describes numerical simulations of the problem investigated experimentally. A three-dimensional finite element model of elastic–plastic for sphere falling on beam has been implemented using the nonlinear dynamic finite element software LS-DYNA. From the numerical simulations, it was found that the LS-DYNA is suitable to study complex sub-impact phenomenon, and good agreement is in general obtained between the simulation and experimental results. The numerical simulations show that the initial impact velocity, equivalent elasticity modulus, contact curvature radius of the sphere, and equivalent mass have great influence on the contact–impact time of the sub-impact, and an applicable range of the theoretical expression of contact–impact time of the sub-impact was determined. In addition, the numerical simulations demonstrate the ratios of maximum amplitudes of the first-, second-, and third-order vibrations to the maximum amplitudes of the beam vibrations, and the phase angle of the first-order vibration will change suddenly when the sub-impacts occur. Furthermore, the occurrence conditions of the sub-impacts were clarified numerically. It was found that the occurrence conditions of the sub-impacts can be represented by a mass ratio threshold, and the thickness or length of the beam has also a great influence on the occurrence of the sub-impacts. Once the sub-impacts occur, which would result in an uncertain behavior of the apparent coefficient of restitution.

  15. Surface analysis, by SNMS, of 316L steel exposed to simulated BWR conditions

    International Nuclear Information System (INIS)

    Buckley, D.; Schenker, E.

    1994-01-01

    Samples of 316L steel have been exposed to Boiling Light Water Reactor chemistry for between forty and seven thousand hours. These samples, with three different surface finishes, 'as-delivered', mechanically polished and electro-polished, have been analysed by Sputtered Neutral Mass Spectrometry and profiles of the constituent alloying elements have been obtained. Differences in the oxide that has built-up are compared and discussed in terms of current ideas of corrosion mechanisms. The structure of the oxide changes with exposure time for the experimental conditions. The effect of surface finish and water velocity have a clear marked effect on the oxide structure and growth rate, respectively: samples in a low water velocity stream form the protective oxide, chromia, and some mixed spinels; electro-polished samples have no chromium layer but show possible secondary passivation through the build-up of nickel; and samples in high velocity water form a simple structured oxide that does not reach a saturation thickness after 291 days but steadily increases. (author) 9 figs., 3 tabs., 7 refs

  16. Corrosion behavior of 316 L stainless steel simulated by studying the influence of the species produced in the radiolysis in tritiated aqueous solutions

    International Nuclear Information System (INIS)

    Bellanger, G.

    1991-10-01

    The corrosion of 316 L stainless steel in tritiated aqueous solutions was simulated by studying the influence of species produced or present in the radiolysis in these solutions. The species studied were nitrates, fluorides, nitrites, hydrogen peroxide and components of the steel, as well as the pH. The method used was voltammetry. The corroded or passivated surfaces were examined by scanning electron microscopy and the corrosion rates were determined by measuring the electrochemical impedance. The depletion of the component elements of the stainless steel at the surface was observed by X-ray fluorescence. From our results we propose methods to limit the corrosion in an industrial tritiated water installation by controlling the pH, the oxidation-reduction potential of the water and the voltage of the installation [fr

  17. The wettability modification of bio-grade stainless steel in contact with simulated physiological liquids by the means of laser irradiation

    International Nuclear Information System (INIS)

    Hao, L.; Lawrence, J.; Li, L.

    2005-01-01

    Early surface events that occur rapidly upon implantation of a biomaterial into biological fluids determine the subsequent response. These involve wetting by physiological liquids followed by adsorption of proteins and cells to the biomaterials surface. A CO 2 laser and high power diode laser (HPDL) were used to modify the surface properties of the material and thus manipulate the wettability of the material and its interaction with physiological liquids. The contact angles, θ, of selected test liquids including simulated physiological liquids shows that the wettability of the stainless steel improved after CO 2 and HPDL treatment. The determined adhesion work of stainless steel towards stimulated physiological fluid enhanced after laser treatment, implying better interaction with the biological liquids. It is demonstrated that the laser could be a novel and controllable technique for enhancing the biocompatibility of bio-grade stainless steel

  18. Injectabilite des coulis de ciment dans des milieux fissures

    Science.gov (United States)

    Mnif, Thameur

    Le travail presente ici est un bilan du travaux de recherche effectues sur l'injectabilite des coulis de ciment dans lu milieux fissures. Un certain nombre de coulis a base de ciment Portland et microfin ont ete selectionnes afin de caracteriser leur capacite a penetrer des milieux fissures. Une partie des essais a ete menee en laboratoire. L'etude rheologique des differents melanges a permis de tester l'influence de l'ajout de superplastifiant et/ou de fumee de silice sur la distribution granulometrique des coulis et par consequent sur leur capacite a injecter des colonnes de sable simulant un milieu fissure donne. La classe granulometrique d'un coulis, sa stabilite et sa fluidite sont apparus comme les trois facteurs principaux pour la reussite d'une injection. Un facteur de finesse a ete defini au cours de cette etude: base sur la classe granulometrique du ciment et sa stabilite, il peut entrer dans la formulation theorique du debit d'injection avant application sur chantier. La deuxieme et derniere partie de l'etude presente les resultats de deux projets de recherche sur l'injection realises sur chantier. L'injection de dalles de beton fissurees a permis le suivi de l'evolution des pressions avec la distance au point d'injection. L'injection de murs de maconnerie a caractere historique a montre l'importance de la definition de criteres de performance des coulis a utiliser pour traiter un milieu donne et pour un objectif donne. Plusieurs melanges peuvent ainsi etre predefinis et mis a disposition sur le chantier. La complementarite des ciments traditionnels et des ciments microfins devient alors un atout important. Le choix d'utilisation de ces melanges est fonction du terrain rencontre. En conclusion, cette recherche etablit une methodologie pour la selection des coulis a base de ciment et des pressions d'injection en fonction de l'ouverture des fissures ou joints de construction.

  19. Simulation of competitive Cu precipitation in steel during non-isothermal aging

    International Nuclear Information System (INIS)

    Yang, J.B.; Yamashita, T.; Sano, N.; Enomoto, M.

    2008-01-01

    A numerical model has been developed to simulate Cu precipitation in dilute bcc Fe-Cu alloys during non-isothermal aging taking into account competitive nucleation at grain boundaries, dislocations and in the matrix, and structural transformation of Cu particles that occurs during growth. The temporal evolution of number density, mean particle size and size distribution during continuous cooling is simulated and is compared with experimental observations under transmission electron microscope and three-dimensional atom probe field ion microscope. With decreasing temperature the growth and coarsening rates diminishes rapidly whereas nucleation continues to occur down to lower temperatures due to the decrease in the activation energy of nucleation and thus, distributions of fine particles can be obtained relatively easily after cooling. Precipitation and dissolution during continuous heating are simulated and are compared with experimental observations in the literature

  20. Numerical simulation of TIG welding with filler of steel pieces of high thickness

    International Nuclear Information System (INIS)

    Carmignani, B.; Toselli, G.

    1999-01-01

    The problem of the numerical simulation of welding process with filler, in particular TIG (tungsten inert gas) with cold filler, has been approached with ABAQUS/S code. Reference has been made to some experimental models studied and prepared ad hoc in order to better know the physical phenomena involved in the TIG welding technique and to validate the computation methodologies and results obtained. This numerical simulation has been required in order to assist the fabrication development and QA for TF (toroidal field) coil case, an important component of ITER (international thermonuclear experimental reactor) machine [it

  1. Simulation of land use evolution by discrete events method: Application to “la chaîne des puys” from XV to XVIII Century

    Directory of Open Access Journals (Sweden)

    Y. Michelin

    1998-01-01

    Full Text Available By using a discrete event method, simulation of land use evolution has been applied to a landscape model of “la ChaÎne des Puys” (French Massif Central during along period (XV–XVIII centuries. The indications concerning the evolution of land use are in conformity with the observation of actual situations but the dynamic changes are faster than in actual facts. In spite of limitations due to necessary simplifications, it is now established that the discrete event method is efficient to simulate land use evolution during a long period. The model is immediately able to describe actual dynamics and to show sensitive variables with their critical values. Although oversimplified, it shows how far factors such as level of crops production and taxation can influence land use and landscape changes with a more or less lengthy period. In the future, the model should be bettered by introducing other determined and/or stochastic events.

  2. Steel corrosion products solubility under conditions simulating various water chemistry parameters in power plants

    International Nuclear Information System (INIS)

    Slobodov, A.A.; Kritskij, V.G.; Zarembo, V.I.; Puchkov, L.V.

    1988-01-01

    To simulate construction material corrosion product mass transfer model in power plant circuits calculation of iron oxide and hydroxide solubility, depending on water chemistry parameters: temperature, pH-value, content of dissolved in water hydrogen and oxygen, is carried out

  3. Surface Studies of Ultra Strength Drilling Steel after Corrosion Fatigue in Simulated Sour Environment

    Energy Technology Data Exchange (ETDEWEB)

    M. Ziomek-Moroz; J.A. Hawk; R. Thodla; F. Gui

    2012-05-06

    The Unites States predicted 60% growth in energy demand by 2030 makes oil and natural gas primary target fuels for energy generation. The fact that the peak of oil production from shallow wells (< 5000 m) is about to be reached, thereby pushing the oil and natural gas industry into deeper wells. However, drilling to depths greater than 5000 m requires increasing the strength-to weight ratio of the drill pipe materials. Grade UD-165 is one of the ultra- high yield strength carbon steels developed for ultra deep drilling (UDD) activities. Drilling UDD wells exposes the drill pipes to Cl{sup -}, HCO{sub 3}{sup -}/CO{sub 3}{sup 2-}, and H{sub 2}S-containig corrosive environments (i.e., sour environments) at higher pressures and temperatures compared to those found in conventional wells. Because of the lack of synergism within the service environment, operational stresses can result in catastrophic brittle failures characteristic for environmentally assisted cracking (EAC). Approximately 75% of all drill string failures are caused by fatigue or corrosion fatigue. Since there is no literature data on the corrosion fatigue performance of UD-165 in sour environments, research was initiated to better clarify the fatigue crack growth (FCGR) behavior of this alloy in UDD environments. The FCGR behavior of ultra-strength carbon steel, grade UD-165, was investigated by monitoring crack growth rate in deaerated 5%NaCl solution buffered with NaHCO{sub 3}/Na{sub 2}CO{sub 3} and in contact with H{sub 2}S. The partial pressure of H{sub 2}S (p{sub H2S}) was 0.83 kPa and pH of the solution was adjusted by NaOH to 12. The fatigue experiments were performed at 20 and 85 C in an autoclave with surface investigations augmented by scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) spectroscopy. In this study, research focused on surface analyses supported by the fatigue crack growth rate measurements. Fig. 1 shows an SEM micrograph of the crack that propagated from the

  4. Assessment of susceptibility of Type 304 stainless steel to intergranular stress corrosion cracking in simulated Savannah River Reactor environments

    International Nuclear Information System (INIS)

    Ondrejcin, R.S.; Caskey, C.R. Jr.

    1989-01-01

    Intergranular stress corrosion cracking (IGSCC) of Type 304 stainless steel rate tests (CERT) of specimens machined was evaluated by constant extension from Savannah River Plant (SRP) decontaminated process water piping. Results from 12 preliminary CERT tests verified that IGSCC occurred over a wide range of simulated SRP envirorments. 73 specimens were tested in two statistical experimental designs of the central composite class. In one design, testing was done in environments containing hydrogen peroxide; in the other design, hydrogen peroxide was omitted but oxygen was added to the environment. Prediction equations relating IGSCC to temperature and environmental variables were formulated. Temperature was the most important independent variable. IGSCC was severe at 100 to 120C and a threshold temperature between 40C and 55C was identified below which IGSCC did not occur. In environments containing hydrogen peroxide, as in SRP operation, a reduction in chloride concentration from 30 to 2 ppB also significantly reduced IGSCC. Reduction in sulfate concentration from 50 to 7 ppB was effective in reducing IGSCC provided the chloride concentration was 30 ppB or less and temperature was 95C or higher. Presence of hydrogen peroxide in the environment increased IGSCC except when chloride concentration was 11 ppB or less. Actual concentrations of hydrogen peroxide, oxygen and carbon dioxide did not affect IGSCC. Large positive ECP values (+450 to +750 mV Standard Hydrogen Electrode (SHE)) in simulated SRP environments containing hydrogen peroxide and were good agreement with ECP measurements made in SRP reactors, indicating that the simulated environments are representative of SRP reactor environments. Overall CERT results suggest that the most effective method to reduce IGSCC is to reduce chloride and sulfate concentrations

  5. Simulation of creep test on 316FR stainless steel in sodium environment at 550degC

    International Nuclear Information System (INIS)

    Satmoko, A.; Asayama, Tai

    1999-04-01

    In sodium environment, material 316FR stainless steel risks to suffer from carburization. In this study, an analysis using a Fortran program is conducted to evaluate the carbon influence on the creep behavior of 316FR based on experimental results from uni-axial creep test that had been performed at temperature 550degC in sodium environment simulating Fast Breeder Reactor condition. As performed in experiments, two parts are distinguished. At first, elastic-plastic behavior is used to simulate the fact that just before the beginning of creep test, specimen suffers from load or stress much higher than initial yield stress. In second part, creep condition occurs in which the applied load is kept constant. The plastic component should be included, since stresses increase due to section area reduction. For this reason, elastic-plastic-creep behavior is considered. Through time carbon penetration occurs and its concentration is evaluated empirically. This carburization phenomena are assumed to affect in increasing yield stress, decreasing creep strain rate, and increasing creep rupture strength of material. The model is capable of simulating creep test in sodium environment. Material near from surface risks to be carburized. Its material properties change leading to non-uniform distribution of stresses. Those layers of material suffer from stress concentration, and are subject to damage. By introducing a damage criteria, crack initialization can thus be predicted. And even, crack growth can be evaluated. For high stress levels, tensile strength criterion is more important than creep damage criterion. But in low stress levels, the latter gives more influence in fracture. Under high stress, time to rupture of a specimen in sodium environment is shorter than in air. But for stresses lower than 26 kgf/mm 2 , the time to rupture of creep in sodium environment is the same or little longer than in air. Quantitatively, the carburization effect at 550degC is not important. This

  6. Robustness of numerical TIG welding simulation of 3D structures in stainless steel 316L

    International Nuclear Information System (INIS)

    El-Ahmar, W.

    2007-04-01

    The numerical welding simulation is considered to be one of those mechanical problems that have the great level of nonlinearity and which requires a good knowledge in various scientific fields. The 'Robustness Analysis' is a suitable tool to control the quality and guarantee the reliability of numerical welding results. The robustness of a numerical simulation of welding is related to the sensitivity of the modelling assumptions on the input parameters. A simulation is known as robust if the result that it produces is not very sensitive to uncertainties of the input data. The term 'Robust' was coined in statistics by G.E.P. Box in 1953. Various definitions of greater or lesser mathematical rigor are possible for the term, but in general, referring to a statistical estimator, it means 'insensitive to small deviation from the idealized assumptions for which the estimator is optimized. In order to evaluate the robustness of numerical welding simulation, sensitivity analyses on thermomechanical models and parameters have been conducted. At the first step, we research a reference solution which gives the best agreement with the thermal and mechanical experimental results. The second step consists in determining through numerical simulations which parameters have the largest influence on residual stresses induced by the welding process. The residual stresses were predicted using finite element method performed with Code-Aster of EDF and SYSWELD of ESI-GROUP. An analysis of robustness can prove to be heavy and expensive making it an unjustifiable route. However, only with development such tool of analysis can predictive methods become a useful tool for industry. (author)

  7. Numerical investigation by finite element simulation of the bail punch test: application to tempered martensitic steels

    International Nuclear Information System (INIS)

    Campitelli, E.; Spatig, P.; Bertsch, J.

    2007-01-01

    Full text of publication follows: Over the years, the small ball punch test technique has been used to evaluate conventional tensile properties of a variety of materials. The development and use of this type of small specimen techniques is indispensable for an efficient use of the limited irradiation volume of the future fusion material intense neutron source. Up to now, empirical correlations between features of the load-displacement curves of the ball punch test and the mechanical properties, such as the yield stress or the ultimate tensile stress, are established on materials in the unirradiated condition. These correlations are believed to be applicable to irradiated materials and they have been very often used to estimate the irradiation hardening. However, it is well known that the overall constitutive behavior of the materials is generally affected by neutron irradiation. Therefore, there is a need to quantify the effect of the constitutive behavior on the correlations. In this paper, we employ a 3D non-linear finite element model for the ball punch test to address these effects of the irradiation-induced changes on the ball punch test curve. We apply first the model on the tempered martensitic steel EUROFER97 in the unirradiated condition with variations in the post-yield behavior, either in the low strain domain ( 10%). The effects on the ball punch test load deflection curve are outlined. Second, we study the effects of the irradiation hardening on the same constitutive behaviors as those used for the unirradiated condition. We show that that the usual correlations must be considered with great care on irradiated materials since strong variation on the strain-hardening may lead to erroneous estimation of the irradiation hardening. We also propose a novel approach to calibrate the yield stress to features of the ball punch test curve that decreases the uncertainty related to the post-yield behavior and that, as a consequence, makes the technique more

  8. 2-D modelling and simulation of EM brake for liquid steel

    Science.gov (United States)

    Aslan, Necdet; Senturk, Kenan; Tessarotto, Massimo

    2003-11-01

    The problem of EM control of bottom tapping in steelmaking metallurgy is an old and well known challenge not only from the technological viewpoint but also, potentially, an interesting and still open theoretical problem, from the viewpoint of the investigation of the detailed MHD phenomena occurring in EM braking devices [1]. Purpose of the present work is the formulation of a 2-D MHD model for a DC EM braking device, which includes the consistent modelization of inductive EM fields produced by the conductive fluid, large scale turbulence, boundary conditions for the EM fields and thermal effects. The mathematical model has been implemented in a new 2-D MHD code developed for this purpose [2], based on the so-called fluctuation splitting and dual-time stepping methods, respectively, to advance in time the fluid fields and satisfy the relevant incompressibility-solenoidality conditions for the fluid mass velocity and the magnetic field. Main goal of the investigation is the analysis of the nonlinear phenomena occurring in the process of slowing down of a column of liquid steel under the action of the EM brake, and in particular the detailed description of the effects of large scale turbulence produced by the action of Lorentz force on the fluid, their influence on the magnitude of the inductive EM fields and the performance of the EM brake itself. REFERENCES [1] A.Codutti, A.Martinis, M.Pavlicevic, M.Tessarotto and D.Batic, Proc. 3rd International Symposium on EMP (Nagoya, Japan, April 2000), p.530 (2000). [2] N.Aslan, K.Senturk and M.Tessarotto, Efficient 2-D solver for incompressible magnefluids, communication at this Conference (2003).

  9. Initiation of cleavage in a low alloy steel: effect of a ductile damage localized around inclusions; Declenchement du clivage dans un acier faiblement allie: role de l'endommagement ductile localise autour des inclusions

    Energy Technology Data Exchange (ETDEWEB)

    Carassou, S

    2000-07-01

    The fracture mechanism in a low alloy steel, used in the pressurised water reactor vessel, has been studied in the ductile to brittle transition temperature range. We used the local approach of fracture in conjunction with both fractographic observations and numerical simulations. Previous studies suggested the onset of cleavage to be favoured by the presence of nearby manganese sulphide (MnS) clusters: the ductile damaged zone localised inside a cluster increases the stress around it, and so contribute to the triggering of cleavage due to nearby classical sites, like carbides. The experimental study of size dependence and anisotropy on the global fracture behaviour, together with fractographic observations, give here the proof of the influence of MnS clusters on the onset of cleavage in this steel. Fracture behaviour of pre-cracked specimens tested in the transition regime has then been simulated, by three dimensional finite element method computations. Ductile tearing process preceding the cleavage onset at those temperatures regime was well reproduced by the Rousselier's model. Failure probabilities, related to given stress states, has been given by post-processor calculations, using a probabilistic model based on the specific cleavage fracture process. Fracture toughness scatter of the steel, tested in the transition regime, is then well reproduced by those calculations. However, the critical cleavage stress of an elementary volume, that scales for the fracture process, is still assumed to be temperature dependant. Numerical simulations of the local fracture process suggest that this temperature effect can partly be explained by the temperature dependant decrease of the stress amplification due to the MnS clusters. (author)

  10. Simulation of creep tests with French or German RPV-steel and investigation of a RPV-support against failure

    International Nuclear Information System (INIS)

    Willschuetz, H.-G.; Altstadt, E.; Sehgal, B.R.; Weiss, F.-P.

    2003-01-01

    Investigating the hypothetical core melt down scenario for a light water reactor (LWR) a possible failure mode of the reactor pressure vessel (RPV) and its failure time has to be considered for a determination of the loadings on the containment. For pre- and post-test calculations of Lower Head Failure experiments like OLHF or FOREVER it is necessary to model creep and plasticity processes. Therefore a Finite Element Model is developed at the FZR using a numerical approach which avoids the use of a single creep law employing constants derived from the data for a limited stress and temperature range. Instead of this a numerical creep data base (CDB) is developed in which the creep strain rate is evaluated in dependence on the current total strain, temperature and equivalent stress. A main task for this approach is the generation and validation of the CDB. Additionally the implementation of all relevant temperature dependent material properties is performed. For the consideration of the tertiary creep stage and for the evaluation of the failure times a damage model according to an approach of Lemaitre is applied. The validation of the numerical model is performed by the simulation of and comparison with experiments. This is done in three levels: starting with the simulation of single uniaxial creep tests, which is considered as a 1D-problem. In the next level so called 'tube-failure-experiments' are modeled: the RUPTHER-14 and the 'MPA-Meppen'-experiment. These experiments are considered as 2D-problems. Finally the numerical model is applied to scaled 3D-experiments, where the lower head of a PWR is represented in its hemispherical shape, like in the FOREVER-experiments. An interesting question to be solved in this frame is the comparability of the French 16MND5 and the German 20MnMoNi5-5 RPV-steels, which are chemically nearly identical. Since these two steels show a similar behavior, it should be allowed to a limited extend to transfer experimental and numerical

  11. Energy-efficient technology in the iron and steel industry: Simulation of new technology adoption with items

    International Nuclear Information System (INIS)

    Roop, J.M.

    1997-01-01

    The Industrial Technology and Energy Modeling System (ITEMS)(referred to as ISTUM in Jaccard and Roop, 1990) is an end-use industrial modeling system that is technology based. Because it includes technologies in the process description of industry, it is possible to introduce new technologies to determine, based on economic and performance data, how rapidly these new technologies will penetrate the market (Hyman and Roop, 1996). As these new technologies penetrate the market, energy savings and, possibly, emissions reductions occur that can be tracked with the model as well. This report documents the use of ITEMS to investigate the impact of three new technologies under development with funding from the Department of Energy's Office of Industrial Technologies (OIT), that apply to the iron and steel industry. While the results of this application are interesting, this exercise points out how important it is to understand how the technologies work and how they make a difference. This report shows that ITEMS can be a useful tool in estimating market penetration of new technologies and the resulting energy savings, but these results are only as reliable as the data. If the model is to be used to compare technologies, the technical data concerning these technologies must be collected using the same set of assumptions and with the same vision of what characterizes a technology. While an effort has been made to understand how these technologies work, there is no assurance that the data used for this analysis were, indeed, collected using the same vision and the same set of assumptions. The report is organized into five additional sections. The next provides a brief overview of ITEMS and describes how the technical information about OIT projects is used in the model. The third section describes the three technologies that were introduced into ITEMS and reports the relevant data for those projects. The fourth section describes the iron and steel industry, as characterized

  12. Numerical Simulation of Multiphase Hydromechanical Processes Induced by CO2 Injection into Deep Saline Aquifers Simulation numérique des processus hydromécaniques polyphasiques provoqués par l’injection de CO2 dans des aquifères salins profonds

    Directory of Open Access Journals (Sweden)

    Goerke U.-J.

    2011-02-01

    Full Text Available In this paper, the conceptual modeling and the numerical simulation of two-phase flow during CO2 injection into deep saline aquifers is presented. The work focuses on isothermal short-term processes in the vicinity of the injection well. Governing differential equations are based on balance laws for mass and momentum, and completed by constitutive relations for the fluid and solid phases as well as their mutual interactions. Constraint conditions for the partial saturations and the pressure fractions of CO2 and brine are defined. To characterize the stress state in the solid matrix, the effective stress principle is applied. The coupled problem is solved using the inhouse scientific code OpenGeoSys (an open source finite element code and verified with benchmarks. Cet article présente le concept de la modélisation ainsi que la simulation numérique d’écoulement biphasé lors de l’injection de CO2 dans des aquifères salins profonds. L’étude se concentre sur des processus à court terme dans la proximité de puits d’injection dans les conditions isothermes. Les équations différentielles principales sont dérivées des équations de bilan de masse et de la quantité de mouvement, et elles sont complétées par des relations constitutives pour des phases solides et fluides ainsi que leur interaction. Les conditions de contrainte sont définies pour la saturation partielle, les fractions de pression de CO2 et l’eau salée. Pour caractériser l’état de contrainte dans la matrice solide, le principe de contrainte effective est appliqué. Le problème couplé considéré est résolu en utilisant le logiciel scientifique interne OpenGeoSys (un logiciel d’éléments finis libre d’accès et vérifié avec des exemples pour les processus concernés.

  13. Localized corrosion of carbon steels due to sulfate-reducing bacteria. Development of a specific sensor; Corrosion localisee des aciers au carbone induite par des bacteries sulfato-reductrices. Developpement d'un capteur specifique

    Energy Technology Data Exchange (ETDEWEB)

    Monfort Moros, N.

    2001-11-01

    This work concerns the microbiologically influenced corrosion of carbon steels in saline anaerobic media (3% of NaCl) containing sulfato-reducing bacteria (Desulfovibrio gabonensis, DSM 10636). In these media, extreme localised corrosion occurs by pitting under the bio-film covering the metallic substrate. A sensor with concentric electrodes was designed to initiate the phenomenon of bio-corrosion, recreating the favourable conditions for growth of a corrosion pit, and then measuring the corrosion current maintained by bacterial activity. The pit initiation was achieved through either of two methods. The electrochemical conditioning involved driving the potential difference between inner and outer electrodes to values corresponding to a galvanic corrosion that can be maintained by the bacterial metabolism. The mechanical process involved removal of a portion of the bio-film by scratching, yielding galvanic potential differences equivalent to that found by the conditioning technique. This protocol was found to be applicable to a bio-corrosion study on industrial site for the monitoring of the metallic structures deterioration (patent EN 00/06114, May 2000). Thereafter, a fundamental application uses the bio-corrosion sensor for Electrochemical Impedance Spectroscopy (EIS), Electrochemical Noise Analysis (ENA) and current density cartography by the means of micro-electrodes. Thus, the EIS technique reveals the importance of the FeS corrosion products for initiation of bio-corrosion start on carbon steel. In addition, depending on the method used to create a pit, the ENA gives rise to supplementary processes (gaseous release) disturbing the bio-corrosion detection. The beginning of a bio-corrosion process on a clean surface surrounded with bio-film was confirmed by the current density cartography. These different results establish the sensor with concentric electrodes as an indispensable tool for bio-corrosion studies, both in the laboratory and on industrial sites

  14. Phase transformation and impact properties in the experimentally simulated weld heat-affected zone of a reduced activation ferritic/martensitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Joonoh, E-mail: mjo99@kims.re.kr [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Lee, Chang-Hoon; Lee, Tae-Ho [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Jang, Min-Ho [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Division of Materials Science and Engineering, Hanyang University, Seongdong-ku, Seoul 133-791 (Korea, Republic of); Park, Min-Gu [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Department of Material Science and Engineering, Pusan National University, 30 Jangjeon-Dong, Geumjeong-gu, Pusan 609-735 (Korea, Republic of); Han, Heung Nam [Department of Materials Science and Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of)

    2014-12-15

    In this work, the phase transformation and impact properties in the weld heat-affected zone (HAZ) of a reduced activation ferritic/martensitic (RAFM) steel are investigated. The HAZs were experimentally simulated using a Gleeble simulator. The base steel consisted of tempered martensite through normalizing at 1000 °C and tempering at 750 °C, while the HAZs consisted of martensite, δ-ferrite and a small volume of autotempered martensite. The impact properties using a Charpy V-notch impact test revealed that the HAZs showed poor impact properties due to the formation of martensite and δ-ferrite as compared with the base steel. In addition, the impact properties of the HAZs further deteriorated with an increase in the δ-ferrite fraction caused by increasing the peak temperature. The impact properties of the HAZs could be improved through the formation of tempered martensite after post weld heat treatment (PWHT), but they remained lower than that of the base steel because the δ-ferrite remained in the tempered HAZs.

  15. A study of the evolution of rust on Mo–Cu-bearing fire-resistant steel submitted to simulated atmospheric corrosion

    International Nuclear Information System (INIS)

    Hao Long; Zhang Sixun; Dong Junhua; Ke Wei

    2012-01-01

    Highlights: ► The rusting evolution of a Mo–Cu-bearing fire-resistant steel in a simulated industrial atmosphere was investigated. ► The rusting evolution of the steel is related to the rust composition, structure, and electrochemical characteristics. ► Increased content of α-FeOOH and decreased γ-FeOOH and Fe 3 O 4 indicate the enhanced resistance of the rust. ► Mo and Cu are involved in the formation of molybdate and Cu(I)-bearing compounds in the rust. - Abstract: The corrosion evolution of a Mo–Cu-bearing fire-resistant steel in a simulated industrial atmosphere was investigated by corrosion weight gain, XRD, EPMA, XPS, and polarization curves. The results indicate that the corrosion kinetics is closely related to the rust composition and electrochemical properties. As the corrosion proceeds, the relative content of γ-FeOOH and Fe 3 O 4 decreases and α-FeOOH increases, and the rust layer becomes compact and adherent to steel substrate. Molybdenum and copper enrich in the inner rust layer, especially at the bottom of the corrosion nest, forming non-soluble molybdate and Cu(I)-bearing compounds responsible for enhanced corrosion resistance of the rust layer.

  16. Effect of Welding Thermal Cycles on Microstructure and Mechanical Properties of Simulated Heat Affected Zone for a Weldox 1300 Ultra-High Strength Alloy Steel

    Directory of Open Access Journals (Sweden)

    Węglowski M. St.

    2016-03-01

    Full Text Available In the present study, the investigation of weldability of ultra-high strength steel has been presented. The thermal simulated samples were used to investigate the effect of welding cooling time t8/5 on microstructure and mechanical properties of heat affected zone (HAZ for a Weldox 1300 ultra-high strength steel. In the frame of these investigation the microstructure was studied by light and transmission electron microscopies. Mechanical properties of parent material were analysed by tensile, impact and hardness tests. In details the influence of cooling time in the range of 2,5 ÷ 300 sec. on hardness, impact toughness and microstructure of simulated HAZ was studied by using welding thermal simulation test. The microstructure of ultra-high strength steel is mainly composed of tempered martensite. The results show that the impact toughness and hardness decrease with increase of t8/5 under condition of a single thermal cycle in simulated HAZ. The increase of cooling time to 300 s causes that the microstructure consists of ferrite and bainite mixture. Lower hardness, for t8/5 ≥ 60 s indicated that low risk of cold cracking in HAZ for longer cooling time, exists.

  17. Analog simulation of concentration transients in a gaseous diffusion plant (1961); Etude sur simulateur des regimes transitoires des concentrations dans une installation de diffusion gazeuse (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Delarousse, P; Trouve, C; Jacques, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    A finite difference system is used to describe concentration transients in a gaseous diffusion plant for uranium isotope separation. The equipment used in this study is described and examples are given to illustrate the problems which have been solved with it. (authors) [French] Le comportement transitoire d'une cascade de diffusion gazeuse est represente de facon approchee par un systeme differentiel aux differences. On decrit le materiel analogique original qui a permis de simuler ce systeme. Une serie d'exemples illustre les differents problemes qui ont ete resolus au moyen de cet appareil. (auteurs)

  18. The effect of simulated inflammatory conditions on the surface properties of titanium and stainless steel and their importance as biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca-García, Abril [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México (Mexico); Posgrado en Ciencia e Ingeniería de Materiales, Universidad Nacional Autónoma de México, México (Mexico); Pérez-Alvarez, J. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México (Mexico); Barrera, C.C. [Posgrado en Ciencias Médicas, Odontológicas y de la Salud, Universidad Nacional Autónoma de México, México (Mexico); Medina, J.C. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México (Mexico); Posgrado en Ciencia e Ingeniería de Materiales, Universidad Nacional Autónoma de México, México (Mexico); Almaguer-Flores, A. [Facultad de Odontología, Universidad Nacional Autónoma de México, México (Mexico); Sánchez, R. Basurto [Instituto Nacional de Investigaciones Nucleares, México (Mexico); and others

    2016-09-01

    This work compares the surface modifications induced by the immersion in solutions that simulate inflammatory conditions of pure titanium (cpTi) and medical grade stainless steel (SS). The inflammatory conditions were simulated using a mixture of Hartman solution and 50 mM of hydrogen peroxide (H{sub 2}O{sub 2}) at pH = 5.2. The samples were immersed by 7 days refreshing the solution every day to keep the reactivity of the H{sub 2}O{sub 2}. The surface characteristics that were investigated were: elemental composition by X-ray photoelectron spectroscopy (XPS); topography by atomic force microscopy (AFM) and profilometry; wettability and surface energy by sessile drop contact angle and point of zero charge by titration. Moreover, the variations in the electrochemical response were evaluated by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP) performed before and after the treatment using the Hartman solution as the electrolyte. The XPS results indicated that for both metallic samples, oxidation of the surface was promoted and/or the oxide layer was thicker after the immersion. The roughness and the solid-liquid surface energy were increased; the samples showed a more hydrophilic character after the treatment. However, the surface energy of the solid estimated using the Van Oss–Chaudhury–Good approach showed different trends between the cpTi and the SS surfaces; the polar component decreased for cpTi, while it increased for SS. Finally, the electrochemical results indicated that the corrosion resistance (R{sub cor}) and the pore resistance (R{sub po}) significantly decreased for cpTi, while both resistances were not significantly different for the SS. This is indicative of a higher dissolution of the cpTi compared to SS and the lower R{sub po} means that the species are easily transported through the surface layer, which can be explained in terms of the formation of a porous TiO{sub x} layer, not

  19. Contribution of archaeological analogs to the estimation of average corrosion rates and long term corrosion mechanisms of low carbon steel in soil; Apport des analogues archeologiques a l'estimation des vitesses moyennes et a l'etude des mecanismes de corrosion a tres long terme des aciers non allies dans les sols

    Energy Technology Data Exchange (ETDEWEB)

    Neff, D

    2003-11-15

    In the context of the French nuclear waste storage, a multi-barriers disposal is envisaged. Wastes could be put in metallic overpacks disposed in a clay soil. As these overpacks could be made of low carbon steel, it is important to understand the corrosion behaviour of this material in soil during period of several centuries. Indeed, it is necessary to consolidate the empirical data by a phenomenological approach. This includes laboratory experiments and modelling of the phenomenon which have to be validated and completed by the study of archaeological artefacts. This was the aim of this PhD-work. To this purpose, an analytical protocol has been elaborated: about forty archaeological artefacts coming from five dated sites (2. to 16. centuries) have been studied on cross section in order to observe on the same sample all the constituents of the system: metallic substrate/corrosion products/environment. The corrosion products are divided into two zones: the Dense Product Layer (DPL) in contact with the metal, and the Transformed Medium (TM) which are the corrosion products formed around soil minerals (quartz grains). The metallic substrate has been studied by the classical methods of materials science (optical and scanning electron microscope, energy and wavelength dispersive spectroscopies). It has been verified that despite their heterogeneity of structure and composition, they are all hypo-eutectoids steels that can contain phosphorous until 0.5 wt%. The corrosion products have been analysed by local structural analytical methods as micro-diffraction under synchrotron radiation ({mu}XRD) and Raman micro-spectroscopy. These two complementary techniques and also the elemental composition analysis conducted to the characterisation of the corrosion forms. On the majority of the samples coming from four sites, the DPL are constituted by goethite including marbles of magnetite/maghemite. On the artefacts from the fifth site, a particular corrosion form has been

  20. Rôle des additifs anti-usure des huiles lubrifiantes dans un teste de frottement simulant le contact segment-chemise Role of Antiwear Additives for Lube Oils in a Friction Test Simulating Ring-Liner Contact

    Directory of Open Access Journals (Sweden)

    Martin J. M.

    2006-11-01

    Full Text Available Nous avons mis en oeuvre un test de frottement dans lequel les conditions tribologiques sont voisines de celles existant au niveau segment-chemise des moteurs à explosion. Nous avons éprouvé différentes huiles commerciales ainsi que des additifs purs. Ayant choisi la température comme paramètre variable au cours de ce test nous pouvons déterminer pour chaque lubrifiant une plage de température correspondant à une zone d'efficacité maximale de l'additif anti-usure qu'il contient. La température correspondant à la limite inférieure de cette plage est liée à la nature chimique de l'additif. De plus lorsqu'un gradient de température existe entre les deux pièces en frottement, on observe, dans la zone d'efficacité maximale du lubrifiant, un phénomène de pulsations verticales de la goutte d'huile placée dans le contact. Des éléments d'interprétation, expliquant ces deux phénomènes, sont proposés et conduisent à relier l'efficacité anti-usure d'un additif à ses propriétés d'adsorption à la surface des pièces frottantes. The tribological conditions in the test used were similar to these existing in the ringliner area. of explosion engines. Different commercial cils were tested along with pure additives. Since temperature was chosen as a variable parameter during these tests, it was possible to determine a temperature range for each lubricant, corresponding to the maximum efficiency zone for the antiwear additive it contained. The temperature corresponding to the lower limit of this range is linked to the chemical nature of the additive. Likewise, when a temperature gradient exists between two rubbing parts, a vertical pulsation phenomenon of the drop of cil n the contact area occurs in the maximum efficiency zone of the lubricant. Interpretation elements explaining these two phenomena are proposed and lead to linking the antiwear efficiency of an additive to its adsorption properties on the surface of rubbing parts.

  1. Numerical simulation of a Charpy test and correlation of fracture toughness with fracture energy. Vessel steel and duplex stainless steel of the primary loop

    International Nuclear Information System (INIS)

    Breban, P; Eripret, C.

    1995-01-01

    The analysis methods used to evaluate the harmlessness of defects in the components of the primary coolant circuit of pressurized water reactor are based on the knowledge of the failure properties of concerned materials. The toughness is used to be measured through tests performed on normalized samples. But in some cases, especially for the vessel steel submitted to irradiation effects or for cast components in duplex stainless steel sensitive to thermal ageing, these measurements are not available on the material aged in operation. Therefore, fracture resistance has been evaluated through Charpy tests. Toughness is thus obtained on the basis of an empirical correlation. To improve these predictions, a modeling of the Charpy test in the framework of the local approach to fracture has been performed, for both materials. For the vessel steel, a complete evaluation of toughness has been achieved on the basis of a bidimensional viscoplastic modeling under large strain assumptions and a post-treatment with a Weibull model (cleavage fracture). The main hypothesis (partition between plain stress and plain strain areas in the bidimensional modeling) was corrected after a three dimensional calculations with the finite element program Code-Aster. The fracture analysis put into evidence that damage considerations like cavity nucleation and growth have to be introduced in the model in order to improve the description of physical phenomena. Two ways of progress have been suggested and are in course of being investigated, one in the framework of local approach to failure, the other with the help of micro-macro relationship. With regard to the duplex steel, the description of a Charpy (U) test allowed to clearly discriminate between crack initiation and propagation phases. A modeling through an equivalent homogenous material with a damage law based on a modified Gurson potential enables to describe quantitatively both phases of fracture. It clearly appears that a reliable

  2. Ion bombardment effects on the fatigue life of stainless steel under simulated fusion first wall conditions

    International Nuclear Information System (INIS)

    Kohse, G.; Harling, O.K.

    1983-01-01

    Pressurized tube specimens have been exposed to simultaneous multi-energy surface ion bombardment, fast neutron irradiation and stress and temperature cycling, in a simulation of a possible fusion reactor first wall environment. After ion bombardments equivalent to months-years of reactor operation and up to 30,000 cycles, no detrimental effects on post-irradiation fatigue life were found. The ion damage is found to enhance surface cracking, but this effect is limited to the several micron surface layer in which the ions are implanted

  3. Effect of welding heat input on microstructures and toughness in simulated CGHAZ of V–N high strength steel

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jun, E-mail: hujunral@163.com [The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Du, Lin-Xiu [The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Wang, Jian-Jun [Institute of Materials Research, School of Material and Metallurgy, Northeastern university, Shenyang 110819 (China); Gao, Cai-Ru [The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China)

    2013-08-10

    For the purpose of obtaining the appropriate heat input in the simulated weld CGHAZ of the hot-rolled V–N microalloyed high strength S-lean steel, the microstructural evolution, hardness, and toughness subjected to four different heat inputs were investigated. The results indicate that the hardness decreases with increase in the heat input, while the toughness first increases and then decreases. Moderate heat input is optimum, and the microstructure is fine polygonal ferrite, granular bainite, and acicular ferrite with dispersive nano-scale V(C,N) precipitates. The hardness is well-matched with that of the base metal. Moreover, the occurrence of energy dissipating micromechanisms (ductile dimples, tear ridges) contributes to the maximum total impact energy. The detrimental effect of the free N atoms on the toughness can be partly remedied by optimizing the microstructural type, fraction, morphologies, and crystallographic characteristics. The potency of V(C,N) precipitates on intragranular ferrite nucleation without MnS assistance under different heat inputs was discussed.

  4. Evaluation between residual stresses obtained by neutron diffraction and simulation for dual phase steel welded by laser process

    Science.gov (United States)

    Kouadri-Henni, Afia; Malard, Benoit

    2018-05-01

    This study aimed at characterizing the residual stresses (RS) distribution of a Dual Phase Steel (DP600) undergoing a Laser Beam Welding (LBW) with two different laser parameters. The RS in the ferritic phase have been experimentally determined by the use of the neutrons diffraction technique. The results confirmed a gradient of RS among different zones both on the top and below surfaces but also through the thickness of the fusion zone. Low compressive stresses were observed in the Base Metal (BM) close to the Heat Affected Zone (HAZ) whereas high tensile stresses were observed in the Fusion Zone (FZ). Numerical results showed a difference in the RS distribution depending on the model used. In the end, it appears that the high temperature gradient, specific to the laser beam, is the main factor governing the RS. Our results suggest as well that the approach regarding the RS should consider not only the temperature but also process parameters. When comparing simulation results with experimental data, the values converge well in some zones, in particular the FZ and the others less.

  5. Hydrothermal calcium modification of 316L stainless steel and its apatite forming ability in simulated body fluid.

    Science.gov (United States)

    Valanezahad, Alireza; Ishikawa, Kunio; Tsuru, Kanji; Maruta, Michito; Matsuya, Shigeki

    2011-01-01

    To understand the feasibility of calcium (Ca) modification of type 316L stainless steel (316L SS) surface using hydrothermal treatment, 316L SS plates were treated hydrothermally in calcium chloride (CaCl(2)) solution. X-ray photoelectron spectroscopic analysis revealed that the surface of 316L SS plate was modified with Ca after hydrothermal treatment at 200°C. And the immobilized Ca increased with CaCl(2) concentration. However no Ca-modification was occurred for 316L SS plates treated at 100°C. When Ca-modified 316L SS plate was immersed in simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma, low crystalline apatite was precipitated on its surface whereas no precipitate was observed on non Ca-modified 316L SS. The results obtained in the present study indicated that hydrothermal treatment at 200°C in CaCl(2) solution is useful for Ca-modification of 316L SS, and Ca-modification plays important role for apatite precipitation in SBF.

  6. Modeling and Simulated Annealing Optimization of Surface Roughness in CO2 Laser Nitrogen Cutting of Stainless Steel

    Directory of Open Access Journals (Sweden)

    M. Madić

    2013-09-01

    Full Text Available This paper presents a systematic methodology for empirical modeling and optimization of surface roughness in nitrogen, CO2 laser cutting of stainless steel . The surface roughness prediction model was developed in terms of laser power , cutting speed , assist gas pressure and focus position by using The artificial neural network ( ANN . To cover a wider range of laser cutting parameters and obtain an experimental database for the ANN model development, Taguchi 's L27 orthogonal array was implemented in the experimental plan. The developed ANN model was expressed as an explicit nonlinear function , while the influence of laser cutting parameters and their interactions on surface roughness were analyzed by generating 2D and 3D plots . The final goal of the experimental study Focuses on the determinationof the optimum laser cutting parameters for the minimization of surface roughness . Since the solution space of the developed ANN model is complex, and the possibility of many local solutions is great, simulated annealing (SA was selected as a method for the optimization of surface roughness.

  7. Simulation of Drawing of Small Stainless Steel Platinum Medical Tubes--Influence of the Tool Parameters on the Forming Limit

    International Nuclear Information System (INIS)

    Linardon, Camille; Affagard, Jean-Sebastien; Chagnon, Gregory; Favier, Denis; Gruez, Benoit

    2011-01-01

    Tube cold drawing processes are used to reduce tube diameters and thickness, while pulling them through a conical converging die with or without inner plug. An accurate modelling of the material deformation and friction behaviour is required in order to well describe these processes.The study concerns a stainless steel platinum alloy. The material behaviour is characterised through tensile tests at strain rates as close as possible to the high strain rates reached during the drawing process. The results are fitted with an isotropic temperature-independent Johnson Cook constitutive equation. The modelling of floating plug drawing is performed on a ABAQUS/Explicit model. Friction coefficient is difficult to estimate with mechanical experimental tests, thus an inverse analysis is carried out to fit this parameter thanks to finite element simulation and experimental drawing tests. Drawing force measurements are recorded during the forming process. The Cockroft-Latham criterion is applied to understand the different process parameters influence on tube drawing and its accuracy for drawing process is evaluated.

  8. Numerical simulations of the dynamic of steel catenary riser under the influence of VIV-Vortex-Induced Vibration

    Energy Technology Data Exchange (ETDEWEB)

    Tsukada, Raphael I.; Morooka, Celso K. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica; Franciss, Ricardo; Matt, Cyntia G.C. [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

    2009-07-01

    Hydrocarbon discoveries in ultra deep waters and the recent pre-salt deep carbonate reservoirs along the Brazilian coast demand further technological development in order to exploit these resources. These developments usually require new concepts for offshore sea surface structures and subsea systems for the petroleum and gas production, which means cost effective solutions that provides higher operational safety on drilling and production operations. In this scenario, the effect of the natural phenomenon of Vortex-Induced Vibration (VIV) on risers is one of the concerns for its design due to the tendency of VIV to increase levels of stresses in the riser structure. Therefore the correct prediction of stresses and displacements due to VIV is of great importance for designing riser systems. The present work presents new developments based on previous results for VIV in vertical risers extended to curved risers such as steel catenary risers (SCR). Numerical simulations have been performed in time domain, and experimental results from model tests with a scaled SCR in a towing tank have been used to evaluate the proposed developments. Finally, the conclusions from the analysis of the results bring very promising results. (author)

  9. LHS (latin hypercubes) sampling of the material properties of steels for the analysis of the global sensitivity in welding numerical simulation

    International Nuclear Information System (INIS)

    Petelet, Matthieu; Asserin, Olivier; Iooss, Bertrand; Petelet, Matthieu; Loredo, Alexandre

    2006-01-01

    In this work, the method of sensitivity analysis allowing to identify the inlet data the most influential on the variability of the responses (residual stresses and distortions). Classically, the sensitivity analysis is carried out locally what limits its validity domain to a given material. A global sensitivity analysis method is proposed; it allows to cover a material domain as wide as those of the steels series. A probabilistic modeling giving the variability of the material parameters in the steels series is proposed. The original aspect of this work consists in the use of the sampling method by latin hypercubes (LHS) of the material parameters which forms the inlet data (dependent of temperature) of the numerical simulations. Thus, a statistical approach has been applied to the welding numerical simulation: LHS sampling of the material properties, global sensitivity analysis what has allowed the reduction of the material parameterization. (O.M.)

  10. Numerical simulation of impact bend tests on araldite B and steel specimens

    International Nuclear Information System (INIS)

    Stoeckl, H.; Boehme, W.

    1983-09-01

    As a preliminary stage in the numerical simulation of impact bend tests on elastic-plastic sample materials some simpler experiments were calculated for this report, some of which occured without crack propagation, others with linear elastic crack propagation. These calculations were performed with an own program based on the method of finite differences and also with the finite element program ADINA. In the numerical models plane stress was assumed. Crack propagation was governed by a relation between crack velocity and stress intensity factor. As load input the measured hammer load was used in some cases, mass and initial velocity of the hammer in others. The sample looses contact to the anvils and to the hammer for some time, which had to be considered in model building. The stiffening of the model in the contact region caused by the discretization had to be compensated by springs inserted between the sample and the anvils. The simulation reproduces the experimentally observed behaviour of the sample quite well. Furthermore, additional information can be extracted from the experiment, e.g. concerning the partition of the impact energy. (orig.) [de

  11. Study of the Effect of Mold Corner Shape on the Initial Solidification Behavior of Molten Steel Using Mold Simulator

    Science.gov (United States)

    Lyu, Peisheng; Wang, Wanlin; Long, Xukai; Zhang, Kaixuan; Gao, Erzhuo; Qin, Rongshan

    2018-02-01

    The chamfered mold with a typical corner shape (angle between the chamfered face and hot face is 45 deg) was applied to the mold simulator study in this paper, and the results were compared with the previous results from a well-developed right-angle mold simulator system. The results suggested that the designed chamfered structure would increase the thermal resistance and weaken the two-dimensional heat transfer around the mold corner, causing the homogeneity of the mold surface temperatures and heat fluxes. In addition, the chamfered structure can decrease the fluctuation of the steel level and the liquid slag flow around the meniscus at mold corner. The cooling intensities at different longitudinal sections of shell are close to each other due to the similar time-average solidification factors, which are 2.392 mm/s1/2 (section A-A: chamfered center), 2.372 mm/s1/2 (section B-B: 135 deg corner), and 2.380 mm/s1/2 (section D-D: face), respectively. For the same oscillation mark (OM), the heights of OM roots at different positions (profile L1 (face), profile L2 (135 deg corner), and profile L3 (chamfered center)) are very close to each other. The average value of height difference (HD) between two OMs roots for L1 and L2 is 0.22 mm, and for L2 and L3 is 0.38 mm. Finally, with the help of metallographic examination, the shapes of different hooks were also discussed.

  12. Fatigue-creep of martensitic steels containing 9-12% Cr: behaviour and damage; Fatigue-fluage des aciers martensitiques a 9-12% Cr: comportement et endommagement

    Energy Technology Data Exchange (ETDEWEB)

    Fournier, B

    2007-09-15

    It is in the framework of the research programs on nuclear reactors (generation IV) that the martensitic steels containing 9-12% Cr are studied by the CEA. Most of the structures for which they are considered will be solicited in fatigue-creep at high temperature (550 C). The aim of this work is to understand and model the cyclic behaviour and the damage of these materials. The proposed modelling are based on detailed observations studies (SEM, TEM, EBSD...). The cyclic softening is attributed to the growth of the microstructure. A micro-mechanical model based on the physical parameters is proposed and leads to encouraging results. The damage results of interactions between fatigue, creep and oxidation. Two main types of damage are revealed. A model of anticipation of service time is proposed and gives very satisfying results. The possible extrapolations are discussed. (O.M.)

  13. Behaviour and damage of aged austenitic-ferritic steels: a micro-mechanical approach; Comportement et endommagement des aciers austeno-ferritiques vieillis: une approche micromecanique

    Energy Technology Data Exchange (ETDEWEB)

    Bugat, St

    2000-12-15

    The austenitic-ferritic steels are used in the PWR primary cooling system. At the running temperature (320 C), they are submitted to a slow aging, which leads to the embrittlement of the ferritic phase. This embrittlement leads to a decrease of the mechanical properties, in particular of the crack resistance of the austenitic-ferritic steels. The damage and rupture of the austenitic-ferritic steels have been approached at the ENSMP by the works of P. Joly (1992) and of L. Devilliers-Guerville (1998). These works have allowed to reveal a damage heterogeneity which induces a strong dispersion on the ductilities and the toughnesses as well as on the scale effects. Modeling including the damage growth kinetics measured experimentally, have allowed to verify these effects. Nevertheless, they do not consider the two-phase character of the material and do not include a physical model of the cleavage cracks growth which appear in the embrittled ferrite. In this study, is proposed a description of the material allowing to treat these aspects while authorizing the structure calculation. In a first part, the material is studied. The use of the ESBD allows to specify the complex morphology of these steels and crystal orientation relations between the two phases. Moreover, it is shown that the two phases keep the same crystal orientation in the zones, called bicrystals, whose size varies between 500 {mu}m and 1 mm. The study of the sliding lines, coupled to the ESBD, allows to specify too the deformation modes of the two phases. At last, tensile and tensile-compression tests at various deformation range are carried out to characterize the macroscopic mechanical behaviour of these materials. Then, a micro-mechanical modeling of the material behaviour is proposed. This one takes into account the three scales identified at the preceding chapter. The first scale, corresponding to the laths is described as a monocrystal whose behaviour includes both an isotropic and a kinematic

  14. Microstructural study of thermally aged duplex stainless steel deformation and fracture modes; Etude microstructurale des modes de deformation et de rupture d`un acier austenoferritique vieilli thermiquement

    Energy Technology Data Exchange (ETDEWEB)

    Verhaeghe, B. [Institut national polytechnique, 38 - Grenoble (France)

    1996-12-31

    The aim of this work is to study the micro mechanisms of deformation and rupture of an austeno ferritic stainless steel (Z 3 CND 22-10 M) with 33 % of ferrite. It is studied after ageing 1 000 h at 400 deg. C and 8 000 h at 350 deg. C and compared to the `as received` state. During ageing the ferritic phase undergoes microstructural evolutions which affects its properties. The two ageing treatments lead to roughly the same level of embrittlement. Microstructural characterisation shows that both phases percolate and exhibit orientation relationships close to Kurdjumov-Sachs ones. Mechanical properties of the steel were characterised for different ageing treatments at room temperature and at 320 deg. C. The interface is particularly strong and ensures the load transfer to ferrite even if this phase contains cleavage cracks. Moreover the interface does not oppose slip transmission which is instead controlled by localised glide in the ferritic phase. If activated slip systems of austenite are common with ferrite, slip transmission from austenite to ferrite indeed occurs through the=e interface. If they are not common, dislocations cross-slip back into the austenite. At 320 deg. C cross-slip occurs even far from the interface. Damage starts by nucleation in ferrite of cleavage cracks which propagate between austenite islands. Crack propagation is controlled by stretching of austenite ligaments. The material breaks by ductile tearing of austenite islands when the crack eventually percolates in the ferritic phase. The ductility of the material can be correctly describer using a simple model that takes into account the tearing-off the ductile-phase. (author). 153 refs.

  15. Numerical simulation of casting process to assist in defects reduction in complex steel tidal power component

    International Nuclear Information System (INIS)

    Guo, E J; Zhao, S C; Wang, L P; Wu, T; Xin, B P; Tan, J J; Jia, H L

    2016-01-01

    In order to reduce defects and improve casting quality, ProCAST software is performed to study the solidification process of discharge bowl. Simulated results of original casting process show that the hot tearing is serious at the intersection of blades and outer or inner rings. The shrinkage porosity appears at the bottom of discharge bowl and the transition area of wall thickness. Based on the formation mechanisms of the defects, the structure of chills attached on the outer surface of discharge bowl casting is optimized. The thickness of chills ranges from 25mm to 35mm. The positions of chills corresponded to the outer surface of the T-shaped parts. Compared to the original casting design (without chills), the hot tearing and shrinkage porosity of the discharge bowl are greatly improved with addition of chills. (paper)

  16. Residual stresses in surface induction hardening of steels: Comparison between experiment and simulation

    International Nuclear Information System (INIS)

    Coupard, Dominique; Palin-luc, Thierry; Bristiel, Philippe; Ji, Vincent; Dumas, Christian

    2008-01-01

    Deep induction hardening has been performed on two batches of smooth cylindrical specimens with a hardening depth respectively around 2 mm and 3 mm. The distributions of axial and circumferential residual stresses are analysed for the two specimen batches by X-ray diffraction technique. The radial normal stress field is estimated through the use of the well known Moore and Evans correction. Finally, the experimental residual stresses are compared with those obtained from a multiphysic finite element modelling of the whole induction treatment process, including electromagnetic, thermal, metallurgical and mechanical phenomena. The simulated residual stress field is in good agreement with X-ray analysis especially at depths lower than one-tenth the specimen diameter. At deeper depths, a correction of the experimental X-ray analysis has been done to obtain realistic values

  17. Investigation of Reliabilities of Bolt Distances for Bolted Structural Steel Connections by Monte Carlo Simulation Method

    Directory of Open Access Journals (Sweden)

    Ertekin Öztekin Öztekin

    2015-12-01

    Full Text Available Design of the distance of bolts to each other and design of the distance of bolts to the edge of connection plates are made based on minimum and maximum boundary values proposed by structural codes. In this study, reliabilities of those distances were investigated. For this purpose, loading types, bolt types and plate thicknesses were taken as variable parameters. Monte Carlo Simulation (MCS method was used in the reliability computations performed for all combination of those parameters. At the end of study, all reliability index values for all those distances were presented in graphics and tables. Results obtained from this study compared with the values proposed by some structural codes and finally some evaluations were made about those comparisons. Finally, It was emphasized in the end of study that, it would be incorrect of the usage of the same bolt distances in the both traditional designs and the higher reliability level designs.

  18. Numerical simulation of TIG welding with filler of steel pieces of high thickness

    Energy Technology Data Exchange (ETDEWEB)

    Carmignani, B.; Toselli, G. [ENEA Centro Ricerche Ezio Clementel, Bologna (Italy). Dipt. Innovazione

    1999-07-01

    The problem of the numerical simulation of welding process with filler, in particular TIG (tungsten inert gas) with cold filler, has been approached with ABAQUS/S code. Reference has been made to some experimental models studied and prepared ad hoc in order to better know the physical phenomena involved in the TIG welding technique and to validate the computation methodologies and results obtained. This numerical simulation has been required in order to assist the fabrication development and QA for TF (toroidal field) coil case, an important component of ITER (international thermonuclear experimental reactor) machine. [Italian] Con il codice di analisi termo-strutturale non lineare agli EF, ABAQUS/S, viene affrontato per la prima volta il problema della simulazione numerica di un processo di saldatura con materiale d'apporto, in particolare il processo di saldatura TIG (tungsten inert gas) a filo freddo. Si e' fatto riferimento ad alcuni modelli sperimentali studiati e preparati ad hoc per conoscere meglio e valutare le metodologie di calcolo adottate ed i corrispondenti risultati ottenuti. Questo tipo di simulazione e' stato richiesto per fornire alcune conoscenze preliminari, che potessero essere di aiuto e guida nelle scelte di saldatura da eseguire per la fabbricazione e la quality assurance delle casse che dovranno contenere le bobine per la creazione del campo magnetico toroidale nella macchina ITER (international thermonuclear experiemental reactor) per la fusione nucleare. In questo lavoro, sono presentati, analizzati, discussi e confrontati con le corrispondenti misure sperimentali i primi risultati ottenuti. Sono descritte e discusse anche le difficolta' incontrate, le approssimazioni fatte e la ricerca di procedure di calcolo piu' semplificate.

  19. Investigation on impact resistance of steel plate reinforced concrete barriers against aircraft impact. Pt.2: Simulation analysis of scale model impact tests

    International Nuclear Information System (INIS)

    Jun Mizuno; Norihide Koshika; Hiroshi Morikawa; Kentaro Wakimoto; Ryusuke Fukuda

    2005-01-01

    Steel plate reinforced concrete (SC) structure is one in which the rebars of conventional reinforced concrete (RC) structures are replaced with external steel plates attached to inner concrete with headed studs. SC structures are considered to be more effective than RC structures against aircraft impact, so their application to outer walls and roofs of risk-sensitive structures such as nuclear-related structures is expected to mitigate damage to critical components. The objective of this study was to investigate the fracture behavior and perforation thickness of SC panels against aircraft impact through impact tests and simulation analyses. Objectives of this paper are to analytically investigate the protection performance of SC panels against aircraft model impact through simulation analyses of 1/7.5 scale aircraft model impact tests presented in Part 1 of this study using a discrete element method (DEM), and to examine the applicability and validity of the DEM. Simulation analyses by a finite element method (FEM) were also performed to evaluate its applicability. The fracture process and damage to the SC test panels as well as the aircraft models are closely simulated by the discrete element analyses. The various impact responses and failure mechanisms, such as deceleration curves of projectile, velocity of debris from rear face and deformation mode of SC panels, are also simulated closely by the DEM analyses. The results of analyses confirm the shock-proof performance of SC panels against aircraft impact, and the applicability and validity of DEM for evaluating the complex phenomena of an aircraft impact against an SC panel. The finite element analysis closely simulates the deformation of the SC test panel and strains of rear steel plate where the global bending deformation mode is dominant. (authors)

  20. SCC growth behaviors of austenitic stainless steels in simulated PWR primary water

    Science.gov (United States)

    Terachi, T.; Yamada, T.; Miyamoto, T.; Arioka, K.

    2012-07-01

    The rates of SCC growth were measured under simulated PWR primary water conditions (500 ppm B + 2 ppm Li + 30 cm3/kg-H2O-STP DH2) using cold worked 316SS and 304SS. The direct current potential drop method was applied to measure the crack growth rates for 53 specimens. Dependence of the major engineering factors, such as yield strength, temperature and stress intensity was systematically examined. The rates of crack growth were proportional to the 2.9 power of yield strength, and directly proportional to the apparent yield strength. The estimated apparent activation energy was 84 kJ/mol. No significant differences in the SCC growth rates and behaviors were identified between 316SS and 304SS. Based on the measured results, an empirical equation for crack growth rate was proposed for engineering applications. Although there were deviations, 92.8% of the measured crack growth rates did not exceed twice the value calculated by the empirical equation.

  1. Numerical simulation of tearing-fatigue interactions in 316l(N) austenitic stainless steel

    International Nuclear Information System (INIS)

    Sherry, A.H.; Wilkes, M.A.

    2005-01-01

    The loading history of engineering components can influence the behaviour of defects in service. This paper presents, the results of a numerical study aimed at using the Gurson ductile damage model, calibrated against J R-curve data, to simulate load-history effects on ductile tearing behaviour in austenitic materials. The work has demonstrated that ductile crack growth resistance is influenced by sub-critical crack growth by an intervening mechanism such as fatigue. Fatigue crack growth under a positive R-ratio leads to increase in subsequent tearing resistance through three main mechanisms: (i) re-sharpening of the crack tip; (ii) crack extension through the fracture process zone; and (iii) cyclic loading effects on void development. The ratio of minimum to maximum stress during fatigue loading (R-ratio) has been shown to influence subsequent tearing resistance, with an R-ratio of 0.2 generally leading to a greater enhancement in tearing resistance than an R-ratio of 0.1. This behaviour is due to the influence of R-ratio on void development ahead of the fatigue crack tip. Finally, relevant experimental data compare favourably with the predicted J R-curves

  2. Ultrasonic simulation studies for sizing of planar flaws in thick carbon steel welds

    International Nuclear Information System (INIS)

    Prakash, Alok

    2015-01-01

    Ultrasonic non-destructive testing typically involves detection of flaws that may affect the integrity of component under test. Once detected, the flaw is sized for its critical dimensions and its nature. The detection of flaw in the component by ultrasonic test is based on the principle of echo or reflection. Once the echo from a flaw is received, there are several approaches for analyzing the signal so that more and accurate information is obtained on the size of the flaw and its nature. The 6dB drop method is commonly used for sizing of flaws. This technique is based on determining the end points where the ultrasonic signal amplitude from the flaw drops to half of the peak amplitude. Though this method works well for large flaws whose size is larger than the beam width, it has a tendency to oversize the flaw which is smaller than the beam dimensions. In addition to beam divergence, flaw sizing also depends upon the orientation of the flaw with respect to incident sound beam. The paper describes the results of simulation studies on ultrasonic response from planar flaws of various orientations, their imaging and the methodology to be adopted for their accurate depth sizing. The paper also describes the experimental results to validate the flaw sizing approach

  3. Development of novel protective high temperature coatings on heat exchanger steels and their corrosion resistance in simulated coal firing environment

    OpenAIRE

    Rohr, Valentin

    2005-01-01

    Afin d'augmenter leur rendement, les centrales thermiques sont amenées à élever leur température de fonctionnement. Ceci nécessite une amélioration de la résistance à la corrosion des matériaux constitutifs des échangeurs de chaleur. Ainsi, l'objet de cette étude est de développer des revêtements anticorrosion à partir du procédé de cémentation activée. Deux types d'aciers pour échangeurs de chaleur ont été étudiés : un acier austénitique contenant 17% Cr et 13% Ni, et trois aciers ferrito-ma...

  4. Evolution of corrosion of MnCuP weathering steel submitted to wet/dry cyclic tests in a simulated coastal atmosphere

    International Nuclear Information System (INIS)

    Hao Long; Zhang Sixun; Dong Junhua; Ke Wei

    2012-01-01

    Highlights: ► The evolution of rust on MnCuP weathering steel submitted to a simulated coastal atmosphere has been investigated. ► The corrosion evolution of MnCuP weathering steel can be divided into two stages with distinct rust properties. ► A protective rust layer with higher amounts of α-FeOOH and lower Fe 3 O 4 forms as the corrosion proceeds. ► The rust initially enhances and then stabilizes the cathodic process, but the anodic process tends to be inhibited. - Abstract: The evolution of rust on MnCuP weathering steel submitted to a simulated coastal atmosphere was investigated by corrosion weight gain, scanning electron microscopy, X-ray diffraction, and electrochemical methods. The results indicate that the higher corrosion rate during the first stage than that during the second stage is related closely to the rust composition and electrochemical properties. The corrosion rate evolution is caused by the formation of a protective rust layer with a higher relative amount of α-FeOOH. The rust initially enhances and then stabilizes the cathodic process, but the anodic process tends to be inhibited by the protective rust layer.

  5. Fuel performance computer code simulation of steady-state and transient regimes of the stainless steel fuel rods

    International Nuclear Information System (INIS)

    Gomes, Daniel de Souza

    2014-01-01

    The immediate cause of the accident at the Fukushima Daiichi nuclear plant in March 2011 was the meltdown of the reactor core. During this process, the zirconium cladding of the fuel reacts with water, producing a large amount of hydrogen. This hydrogen, combined with volatile radioactive materials leaked from the containment vessel and entered the building of the reactor, resulting in explosions. In the past, stainless steel was used as the coating in many pressurized water reactors (PWR) under irradiation and their performance was excellent, however, the stainless steel was replaced by a zirconium-based alloy as a coating material mainly due to its lower section shock-absorbing neutrons. Today, the stainless steel finish appears again as a possible solution for security issues related to the explosion and hydrogen production. The objective of this thesis is to discuss the performance under irradiation of fuel rods using stainless steel as a coating material. The results showed that stainless steel rods exhibit lower temperatures and higher fuel pellet width of the gap - coating the coated rods Zircaloy and this gap does not close during the irradiation. The thermal performance of the two fuel rods is very similar, and the penalty of increased absorption of neutrons due to the use of stainless steel can be offset by the combination of a small increase in the enrichment of U- 235 and changes in the size of the spacing between the fuel rods. (author)

  6. Electrochemical studies of the corrosion behavior of a low-carbon steel in aqueous chloride solutions simulating accident conditions of radioactive waste disposal

    International Nuclear Information System (INIS)

    Farvaque-Bera, A.M.; Leistikow, S.

    1991-01-01

    The fine-grained structural steel DIN W.Nr. 1.0566 was exposed to various sulfate and chloride-containing aqueous solutions, the latter ones simulating the potential accidental environment of water intrusion into a salt mine. By electrochemical measurements in salt brines, the following results were achieved: (1) The corrosion rate is highly dependent on salt brine composition, pH and temperature. (2) Active metal dissolution led to formation of shallow pits as surface corrosion phenomenon. Thus, the application of electrochemical techniques - under non-polarized as well as under potentiodynamic conditions - proved to be suitable for fast qualitative testing of the influence of various environmental parameters on steel corrosion. (orig.)

  7. Crack growth testing of cold worked stainless steel in a simulated PWR primary water environment to assess susceptibility to stress corrosion cracking

    International Nuclear Information System (INIS)

    Tice, D.R.; Stairmand, J.W.; Fairbrother, H.J.; Stock, A.

    2007-01-01

    Although austenitic stainless steels do not show a high degree of susceptibility to stress corrosion cracking (SCC) in PWR primary environments, there is limited evidence from laboratory testing that crack propagation may occur under some conditions for materials in a cold-worked condition. A test program is therefore underway to examine the factors influencing SCC propagation in good quality PWR primary coolant. Type 304 stainless steel was subjected to cold working by either rolling (at ambient or elevated temperature) or fatigue cycling, to produce a range of yield strengths. Compact tension specimens were fabricated from these materials and tested in simulated high temperature (250-300 o C) PWR primary coolant. It was observed that the degree of crack propagation was influenced by the degree of cold work, the crack growth orientation relative to the rolling direction and the method of working. (author)

  8. Developpements numeriques recents realises en aeroelasticite chez Dassault Aviation pour la conception des avions de combat modernes et des avions d’affaires

    Science.gov (United States)

    2003-03-01

    Cost through Advanced Modelling and Virtual Simulation [La reduction des couts et des delais d’acquisition des vehicules militaires par la modelisation...sont les 6quations de restitution, par le mod~e, des frdquences et des amortissements des modes adrodlastiques mesurds h une prdcision F- donnde. Afin... amortissements mesurds h 37800 Pa et 60000 Pa (points nettemnent inferieurs A la vitesse critique). Comme le montre ce diagramme, le calcul, recal6 h

  9. Inelastic constitutive models for the simulation of a cyclic softening behavior of modified 9Cr-lMo steel at elevated temperatures

    International Nuclear Information System (INIS)

    Koo, Gyeong Hoi; Lee, Jae Han

    2007-01-01

    In this paper, the inelastic constitutive models for the simulations of the cyclic softening behavior of the modified 9Cr-1Mo steel, which has a significant cyclic softening characteristic especially in elevated temperature regions, are investigated in detail. To do this, the plastic modulus, which primarily governs the calculation scheme of the plasticity, is formulated for the inelastic constitutive models such as the Armstrong-Frederick model, Chaboche model, and Ohno-Wang model. By implementing the extracted plastic modulus and the consistency conditions into the computer program, the inelastic constitutive parameters are identified to present the best fit of the uniaxial cyclic test data by strain-controlled simulations. From the computer simulations by using the obtained constitutive parameters, it is found that the Armstrong-Frederick model is simple to use but it causes significant overestimated strain results when compared with the Chaboche and the Ohno-Wang models. And from the ratcheting simulation results, it is found that the cyclic softening behavior of the modified 9Cr-1Mo steel can invoke a ratcheting instability when the applied cyclic loads exceed a certain level of the ratchet loading condition

  10. Ajustement statistique des simulations climatiques : l'exemple des précipitations saisonnières de l'Amérique tropicaleStatistical adjustment of simulated climate: example of seasonal rainfall of tropical America.

    Science.gov (United States)

    Moron, Vincent; Navarra, Antonio

    2000-05-01

    This study presents the skill of the seasonal rainfall of tropical America from an ensemble of three 34-year general circulation model (ECHAM 4) simulations forced with observed sea surface temperature between 1961 and 1994. The skill gives a first idea of the amount of potential predictability if the sea surface temperatures are perfectly known some time in advance. We use statistical post-processing based on the leading modes (extracted from Singular Value Decomposition of the covariance matrix between observed and simulated rainfall fields) to improve the raw skill obtained by simple comparison between observations and simulations. It is shown that 36-55 % of the observed seasonal variability is explained by the simulations on a regional basis. Skill is greatest for Brazilian Nordeste (March-May), but also for northern South America or the Caribbean basin in June-September or northern Amazonia in September-November for example.

  11. Data base of climatic change simulations for the impact studies. Final report; Base de donnees des simulations de changement climatique a l'usage des etudes d'impact. Rapport final

    Energy Technology Data Exchange (ETDEWEB)

    Polcher, J.; Leboucher, V.; Planton, S.; Valcke, S

    2003-12-15

    Data used for the study of the climatic change impact on the environment and the society come from climate models and are affected by uncertainties. It is necessary to quantify the resulting errors in the models. The data base provides a comparison of simulations of climatic change in France. The final report presents the project methodology. Three projects using the distributed simulations are also presented. (A.L.B.)

  12. Modelling of microstructural creep damage in welded joints of 316L stainless steel; Modelisation de l'endommagement a haute temperature dans le metal d'apport des joints soudes d'acier inoxydable austenitique

    Energy Technology Data Exchange (ETDEWEB)

    Bouche, G

    2000-07-01

    Welded joints of 316L stainless steel under service conditions at elevated temperature are known to be preferential sites of creep damage, as compared to the base material. This damage results in the formation of cavities and the development of creep cracks which can lead to a premature failure of welded components. The complex two-phase microstructure of 316L welds was simulated by manually filling a mould with longitudinal deposited weld beads. The moulded material was then aged during 2000 hours at 600 deg. C. High resolution Scanning Electron Microscopy was largely used to examine the microstructure of the simulated material before and after ageing. Smooth and notched creep specimens were cut from the mould and tested at 600 deg. C under various stress levels. A comparison of the lifetime versus nominal stress curves for the base and welded materials shows a greater dependence of the welded material to creep phenomena. Observation and EBSD analysis show that damage is preferentially located along the austenite grain boundaries. The stress and strain fields in the notched specimens were calculated by finite element method. A correlation of this field to the observed damage was made in order to propose a predictive law relating the creep damage to the mechanical conditions applied locally. Further mechanical tests and simulation on CT specimens and mode II tubular specimens allowed validating the model under various multiaxial loading conditions. (author)

  13. Effect of welding thermal cycles on the structure and properties of simulated heat-affected zone areas in X10CrMoVNb9-1 (T91) steel at a state after 100,000 h of operation

    Energy Technology Data Exchange (ETDEWEB)

    Łomozik, Mirosław, E-mail: miroslaw.lomozik@is.gliwice.pl [Instytut Spawalnictwa, Testing of Materials Weldability and Welded Constructions Department, 44-100 Gliwice, Bł. Czesława 16-18 (Poland); Hernas, Adam, E-mail: adam.hernas@polsl.pl [Silesian University of Technology, Faculty of Materials Engineering and Metallurgy, 40-019 Katowice, Krasińskiego 8 str. (Poland); Zeman, Marian L., E-mail: marian.zeman@is.gliwice.pl [Instytut Spawalnictwa, Testing of Materials Weldability and Welded Constructions Department, 44-100 Gliwice, Bł. Czesława 16-18 (Poland)

    2015-06-18

    The article presents results of structural tests (light, scanning electron and scanning transmission electron microscopy) of X10CrMoVNb9-1 (T91) creep-resisting steel after approximately 100,000 h of operation. It was ascertained that the parent metal of T91 steel is characterized by the microstructure of tempered martensite with M{sub 23}C{sub 6} carbide precipitates and few dispersive precipitates of MX-type niobium and vanadium carbonitrides. The most inconvenient change in T91 steel precipitate morphology due to long-term operation is the appearance of the Laves Fe{sub 2}Mo phase which along with M{sub 23}C{sub 6} carbide particles forms elongated blocks and conglomerates on grain boundaries. The article also presents results of tests related to the effect of simulated welding thermal cycles on selected properties of X10CrMoVNb9-1 (T91) grade steel at a state after approximately 100,000 h of operation. The tests involved the determination of the chemical composition of the steel tested as well as impact tests, hardness measurements and microscopic metallographic examination (based on light microscopy) of simulated heat-affected zone (HAZ) areas for a cooling time (t{sub 8/5}) restricted within a range between 3 s and 120 s, with and without heat treatment. The tests revealed that, among other results, hardness values of simulated HAZ areas in X10CrMoVNb9-1 (T91) steel do not guarantee cold crack safety of the steel at the state without additional heat treatment. It was also observed that simulated welding thermal cycles of cooling times t{sub 8/5}=3, 12, 60 and 120 s do not significantly affect the toughness and hardness of simulated HAZ areas of the steel tested.

  14. Computer Simulation of Microsegregation of Sulphur and Manganese and Formation of MnS Inclusions while Casting Rail Steel

    Directory of Open Access Journals (Sweden)

    Kalisz D.

    2016-12-01

    Full Text Available The quality of rail steel is conditioned by its high mechanic qualities, which greatly depend on the presence of undesired nonmetallic inclusions. The paper is devoted to the segregation of components, mainly sulphur, and the formation of manganese sulphide in the process of steel solidification, at the casting rate of 100 and 500 K/min. Sulphur is a steel component which disadvantageously influences its numerous parameters. The oxide-sulphide and sulphide precipitations cause cracks and lower the strength of the material. This phenomenon was modeled with the use of author’s computer program based on Matsumiya interdendritic microsegregation model. The main assumptions of this model and thermodynamic conditions of inclusion formation during casting of steel are discussed in this paper. Two cases were analyzed: in the first one the MnS was assumed to form a pure and constant compound, whereas in the other one the manganese sulfide was precipitated as a component of a liquid oxide solution, and its activity was lower than unity. The final conclusion is that chemical composition of steel is the major parameter deciding about the formation of MnS inclusions.

  15. Simulation and experimental comparison of the thermo-mechanical history and 3D microstructure evolution of 304L stainless steel tubes manufactured using LENS

    Science.gov (United States)

    Johnson, Kyle L.; Rodgers, Theron M.; Underwood, Olivia D.; Madison, Jonathan D.; Ford, Kurtis R.; Whetten, Shaun R.; Dagel, Daryl J.; Bishop, Joseph E.

    2017-12-01

    Additive manufacturing enables the production of previously unachievable designs in conjunction with time and cost savings. However, spatially and temporally fluctuating thermal histories can lead to residual stress states and microstructural variations that challenge conventional assumptions used to predict part performance. Numerical simulations offer a viable way to explore the root causes of these characteristics, and can provide insight into methods of controlling them. Here, the thermal history of a 304L stainless steel cylinder produced using the Laser Engineered Net Shape process is simulated using finite element analysis (FEA). The resultant thermal history is coupled to both a solid mechanics FEA simulation to predict residual stress and a kinetic Monte Carlo model to predict the three-dimensional grain structure evolution. Experimental EBSD measurements of grain structure and in-process infrared thermal data are compared to the predictions.

  16. Simulation and experimental comparison of the thermo-mechanical history and 3D microstructure evolution of 304L stainless steel tubes manufactured using LENS

    Science.gov (United States)

    Johnson, Kyle L.; Rodgers, Theron M.; Underwood, Olivia D.; Madison, Jonathan D.; Ford, Kurtis R.; Whetten, Shaun R.; Dagel, Daryl J.; Bishop, Joseph E.

    2018-05-01

    Additive manufacturing enables the production of previously unachievable designs in conjunction with time and cost savings. However, spatially and temporally fluctuating thermal histories can lead to residual stress states and microstructural variations that challenge conventional assumptions used to predict part performance. Numerical simulations offer a viable way to explore the root causes of these characteristics, and can provide insight into methods of controlling them. Here, the thermal history of a 304L stainless steel cylinder produced using the Laser Engineered Net Shape process is simulated using finite element analysis (FEA). The resultant thermal history is coupled to both a solid mechanics FEA simulation to predict residual stress and a kinetic Monte Carlo model to predict the three-dimensional grain structure evolution. Experimental EBSD measurements of grain structure and in-process infrared thermal data are compared to the predictions.

  17. Corrosion studies of carbon steel under impinging jets of simulated slurries of neutralized current acid waste (NCAW) and neutralized cladding removal waste (NCRW)

    International Nuclear Information System (INIS)

    Smith, H.D.; Elmore, M.R.

    1992-01-01

    Plans for the disposal of radioactive liquid and solid wastes presently stored in double-shell tanks at the Hanford Site call for retrieval and processing of the waste to create forms suitable for permanent disposal. Waste will be retrieved from a tank using a submerged slurry pump in conjunction with one or more rotating slurry jet mixer pumps. Pacific Northwest Laboratory (PNL) has conducted tests using simulated waste slurries to assess the effects of a impinging slurry jet on the corrosion rate of the tank wall and floor, an action that could potentially compromise the tank's structural integrity. Corrosion processes were investigated on a laboratory scale with a simulated neutralized cladding removal waste (NCRW) slurry and in a subsequent test with simulated neutralized current acid waste (NCAW) slurry. The test slurries simulated the actual NCRW and NCAW both chemically and physically. The tests simulated those conditions expected to exist in the respective double-shell tanks during waste retrieval operations. Results of both tests indicate that, because of the action of the mixer pump slurry jets, the waste retrieval operations proposed for NCAW and NCRW will moderately accelerate corrosion of the tank wall and floor. Based on the corrosion of initially unoxidized test specimens, and the removal of corrosion products from those specimens, the maximum time-averaged corrosion rates of carbon steel in both waste simulants for the length of the test was ∼4 mil/yr. The protective oxide layer that exists in each storage tank is expected to inhibit corrosion of the carbon steel

  18. Influence of the Periodic Boundary Conditions on the Fluid Structure and on the Thermodynamic Properties Computed from the Molecular Simulations Influence des conditions périodiques sur la structure et sur les propriétés thermodynamiques calculées à partir des simulations moléculaires

    Directory of Open Access Journals (Sweden)

    Janeček J.

    2013-03-01

    Full Text Available The components of pair distribution function in different directions with respect to the coordinate system defined by the simulation box are determined for Lennard-Jones fluid simulated using the Monte Carlo technique in cubic boxes of various size. The approach of Pratt and Haan is employed to analyze the distortion of isotropic fluid structure due to the periodic boundary conditions and qualitative agreement is found between the theoretical and simulated course of particular angular components of distribution function. The relation between the anisotropy of correlation functions and the system size dependency of residual energy and compressibility factor is analyzed. The finite size effects become significantly pronounced in systems with size lower than 5 particle diameters, especially if the length of the box-edge is equal to a non-integer multiple of molecular diameter. With increasing temperature the implicit finite size effects on fluid structure as well as on the thermodynamic properties become less important. The primary cause of the structure deformation lies in the short-range interparticle correlations and the long-range interactions are not important; therefore, the implicit finite size effects influence all kinds of atomistic simulations, including those using the interactions of finite range and in the molecular dynamics simulations. However, at present the simulated systems are usually of sufficiently large size and ignoring the implicit finite size does not lead to serious problems, except for the determination of surface properties using the inhomogeneous simulations which are more sensitive to the lateral dimension of simulation box. Nous avons déterminé les contributions directionnelles de la fonction de distribution par paire du fluide de Lennard-Jones, par simulation moléculaire de Monte Carlo dans des boîtes cubiques de différentes tailles. L’approche de Pratt et Haan est utilisée pour analyser la distorsion de la

  19. Eulerian numerical simulation of gas-solid flows with several particles species; Modelisation numerique eulerienne des ecoulements gaz-solide avec plusieurs especes de particules

    Energy Technology Data Exchange (ETDEWEB)

    Patino-Palacios, G

    2007-11-15

    The simulation of the multiphase flows is currently an important scientific, industrial and economic challenge. The objective of this work is to improve comprehension via simulations of poly-dispersed flows and contribute the modeling and characterizing of its hydrodynamics. The study of gas-solid systems involves the models that takes account the influence of the particles and the effects of the collisions in the context of the momentum transfer. This kind of study is covered on the framework of this thesis. Simulations achieved with the Saturne-polyphasique-Tlse code, developed by Electricite de France and co-worked with the Institut de Mecanique des Fluides de Toulouse, allowed to confirm the feasibility of approach CFD for the hydrodynamic study of the injectors and dense fluidized beds. The stages of validation concern, on the one hand, the placement of the tool for simulation in its current state to make studies of validation and sensitivity of the models and to compare the numerical results with the experimental data. In addition, the development of new physical models and their establishments in the code Saturne will allow the optimization of the industrial process. To carry out this validation in a satisfactory way, a key simulation is made, in particular a monodisperse injection and the radial force of injection in the case of a poly-disperse flow, as well as the fluidization of a column made up of solid particles. In this last case, one approached three configurations of dense fluidized beds, in order to study the influence of the grid on simulations; then, one simulates the operation of a dense fluidized bed with which one characterizes the segregation between two various species of particles. The study of the injection of the poly-disperse flows presents two configurations; a flow Co-current gas-particle in gas (Case Hishida), and in addition, a poly-phase flow in a configuration of the jet type confined with zones of recirculation and stagnation (case

  20. Numerical simulations of electric potential field for alternating current potential drop associated with surface cracks in low-alloy steel nuclear material

    Science.gov (United States)

    Yeh, Chun-Ping; Huang, Jiunn-Yuan

    2018-04-01

    Low-alloy steels used as structural materials in nuclear power plants are subjected to cyclic stresses during power plant operations. As a result, cracks may develop and propagate through the material. The alternating current potential drop technique is used to measure the lengths of cracks in metallic components. The depth of the penetration of the alternating current is assumed to be small compared to the crack length. This assumption allows the adoption of the unfolding technique to simplify the problem to a surface Laplacian field. The numerical modelling of the electric potential and current density distribution prediction model for a compact tension specimen and the unfolded crack model are presented in this paper. The goal of this work is to conduct numerical simulations to reduce deviations occurring in the crack length measurements. Numerical simulations were conducted on AISI 4340 low-alloy steel with different crack lengths to evaluate the electric potential distribution. From the simulated results, an optimised position for voltage measurements in the crack region was proposed.

  1. Experimental determination of heat transfer coefficients in roll bite and air cooling for computer simulations of 1100 MPa carbon steel rolling

    Science.gov (United States)

    Leinonen, Olli; Ilmola, Joonas; Seppälä, Oskari; Pohjonen, Aarne; Paavola, Jussi; Koskenniska, Sami; Larkiola, Jari

    2018-05-01

    In modeling of hot rolling pass schedules the heat transfer phenomena have to be known. Radiation to ambient, between rolls and a steel slab as well as heat transfer in contacts must be considered to achieve accurate temperature distribution and thereby accurate material behavior in simulations. Additional heat is generated by friction between the slab and the work roll and by plastic deformation. These phenomena must be taken into account when the effective heat transfer coefficient is determined from experimental data. In this paper we determine the effective heat transfer coefficient at the contact interface and emissivity factor of slab surface for 1100MPa strength carbon steel for hot rolling simulations. Experimental pilot rolling test were carried out and slab temperatures gathered right below the interface and at the mid thickness of the slab. Emissivity factor tests were carried out in the same manner but without rolling. Experimental data is utilized to derive contact heat transfer coefficient at the interface and emissivity factor of slab surface. Pilot rolling test is reproduced in FE-analysis to further refine the heat transfer coefficient and emissivity factor. Material mechanical properties at rolling temperatures were determined by Gleeble™ thermo-mechanical simulator and IDS thermodynamic-kinetic-empirical software.

  2. Etude et simulation du protocole TTEthernet sur un sous-systeme de gestion de vols et adaptation de la planification des tâches a des fins de simulation

    Science.gov (United States)

    Abidi, Dhafer

    TTEthernet is a deterministic network technology that makes enhancements to Layer 2 Quality-of-Service (QoS) for Ethernet. The components that implement its services enrich the Ethernet functionality with distributed fault-tolerant synchronization, robust temporal partitioning bandwidth and synchronous communication with fixed latency and low jitter. TTEthernet services can facilitate the design of scalable, robust, less complex distributed systems and architectures tolerant to faults. Simulation is nowadays an essential step in critical systems design process and represents a valuable support for validation and performance evaluation. CoRE4INET is a project bringing together all TTEthernet simulation models currently available. It is based on the extension of models of OMNeT ++ INET framework. Our objective is to study and simulate the TTEthernet protocol on a flight management subsystem (FMS). The idea is to use CoRE4INET to design the simulation model of the target system. The problem is that CoRE4INET does not offer a task scheduling tool for TTEthernet network. To overcome this problem we propose an adaptation for simulation purposes of a task scheduling approach based on formal specification of network constraints. The use of Yices solver allowed the translation of the formal specification into an executable program to generate the desired transmission plan. A case study allowed us at the end to assess the impact of the arrangement of Time-Triggered frames offsets on the performance of each type of the system traffic.

  3. Nano-scale study of phase separation in ferrite of long term thermally aged Mo-bearing duplex stainless steels - Atom probe tomography and Monte Carlo simulation

    International Nuclear Information System (INIS)

    Pareige, C.; Emo, J.; Pareige, P.; Saillet, S.; Domain, C.

    2015-01-01

    Duplex stainless steels (DSS), used in primary circuit of Pressurised Water Reactor (PWR), are prone to thermal ageing at service temperature, typically between 286 and 323 C. degrees. This ageing is due to the ferrite decomposition via two kinds of phase transformations: spinodal decomposition into Fe rich α zones and Cr rich α' zones and precipitation of G-phase enriched in Ni, Si, Mn and Mo. It has been shown by atom probe tomography (APT) that the G-phase particles form at the interface between α and α' regions thereby demonstrating that α-α' decomposition and G-phase precipitation are highly dependent. The synergy between the two decomposition processes should be related to both the thermodynamics of the system and the diffusion mechanisms active during ageing. This can be studied by atomistic kinetic Monte Carlo (AKMC) with a model that can reproduce the phase transformations which take place in ferrite of duplex stainless steels. This paper presents the first simulations of the kinetics of spinodal decomposition and G-phase precipitation occurring in ferrite of duplex stainless steels. The kinetics was simulated using a simple but effective atomic kinetic Monte Carlo model in a ternary alloy. The simulations reproduced the α/α' spinodal structure with precipitates at the α/α' interface. The comparison of simulated results with experiments shows that the simulations quantitatively reproduce the kinetics of phase transformation and the synergy observed experimentally between the spinodal decomposition and G-phase precipitation: the time evolution of the wavelength of the spinodal decomposition and the radius of G-phase precipitates were quantitatively reproduced. The simulations endorse the assumption that G-phase precipitation mainly results from the rejection of G-formers from α and α' domains. By following the vacancy pathway during simulation, we show that coarsening of the G-phase precipitates must proceed via

  4. Microstructure Evolution and Chemical Analysis on Carbon Steels and Fe-Cr-Mo Alloys after FAC Simulation Tests

    International Nuclear Information System (INIS)

    Kim, Seunghyun; Kim, Taeho; Lee, Yun Ju; Kim, Ji Hyun

    2017-01-01

    Flow-accelerated corrosion (FAC) is an environment assisted degradation of structural materials, which usually occurs in pipelines of power plants. There have been many studies to investigate the fundamental mechanism and corresponding countermeasures against FAC, and recently the carbon steels have been replaced by ASTM A 335 P22, which contains approximately 2.2 wt.% of Cr and 1 wt.% of Mo. By enhancing passivity of P22 by Cr, it is reported that FAC rate has been greatly reduced. However, while corrosion behavior of Fe-based alloys is relatively well known, their behavior under high-temperature flowing water is not well investigated. In other words, effects of Cr and its corrosion and oxidation behavior is not clearly revealed. Furthermore, it is known that Mo enhances the pitting corrosion resistance of alloys however its mechanism is not clearly investigated. Recently, replacement of Mo in alloy contents has been widely studied because of the cost of Mo. Carbon steels undergo severe environmental-assisted degradation behavior so called FAC, and as its countermeasure the carbon steel has been replaced by P22 which contains Cr and Mo. It is generally known that Cr and Mo enhances passivity of Fe-based alloys however their corrosion and oxidation behavior has not been fully investigated especially in high-temperature flowing water environments. In this study, we employed HRTEM and synchrotron XAS techniques in order to investigate detailed microstructure evolution and chemical bonding of the commercialized carbon steel and the Fe-Cr-Mo alloys. From the analysis, it is found that while carbon steels exhibit porous oxide P22 exhibit oxide structures with thin Cr-rich oxide and spinel. Therefore, carbon steel undergoes severe FAC compared to P22 however effects of Cr and Mo and their behavior in high-temperature flowing water will be investigated.

  5. X-ray photoelectron spectroscopy and electrochemical studies of mild steel FeE500 passivation in concrete simulated water

    Science.gov (United States)

    Miserque, F.; Huet, B.; Azou, G.; Bendjaballah, D.; L'Hostis, V.

    2006-11-01

    In the context of the prediction of the long-term behaviour of reinforced concrete structures involved in the nuclear waste storage, the corrosion mechanisms of steels have to be assessed. When mild steel rebars are embedded in concrete, the chemical environment of the reinforcement is progressively modified, due to the carbonation of the concrete matrix. This modification leads to the variation of iron oxides properties formed at the steel/concrete interface, and the active corrosion can be initiated. The aim of this study is to evaluate the passivation behaviour and to provide insights into the depassivation of mild steel in concrete pore solution. In a young concrete, due to the alkalinity of the interstitial solution, steel reinforcement remains passive. Immersion tests of mild steel substrate in various alkaline solutions (from pH 13 to 10) have been performed. Due to the low thickness of the corrosion layers formed, X-ray photoelectron spectroscopy has been used to characterize them. In the passive domain, the corrosion products are similar for the various solutions. The corrosion layer is composed of a mixture of Fe3+ and Fe2+. A similar approach is used to determine the depassivation mechanism. The effect of various components such as carbonates, sulfates and silicates resulting from the dissolution of minerals of cement during the carbonation process is investigated. In addition to the surface analysis, the evolution of the electrochemical behaviour as function of the solution nature (pH) is evaluated with the help of electrochemical measurements (free corrosion potential, cyclic voltamperometry).

  6. Characteristics of heat affected zone in SAW and SMAW welding of microalloyed steel 450 EMZ studied by means of a welding simulator

    International Nuclear Information System (INIS)

    Gonzalez Palma, R.; Carrillo Olivares, F.; Lopez Torres, E.

    1997-01-01

    In high elastic limit microalloyed steels the heat input remains limited to values around 3 kj/mm, since, from a theoretical point of view the metallurgic transformations produced in the heat affected zone (HAZ) may fragile the metal. The study of the transmission of heat in the HAZ from a theoretical point of view is carried out by solving Rosenthal's equation, which allows us to know the peak temperature reached and the heat cycle in every point of the HAZ. With these data and the CCT curves for 450 EMZ steel corresponding to our steel we will be able to determine the metallurgic transformations produced in those points, with the help of an electron microscope. The welding simulator is valuable help for laboratory study of heat cycles as it allows us to check that for the actual welding processes chosen, i.e. SMAW and SAW, and for the heat input, the transformation products obtained in the HAZ have the right toughness. (Author) 17 refs

  7. Porphyrins as Corrosion Inhibitors for N80 Steel in 3.5% NaCl Solution: Electrochemical, Quantum Chemical, QSAR and Monte Carlo Simulations Studies

    Directory of Open Access Journals (Sweden)

    Ambrish Singh

    2015-08-01

    Full Text Available The inhibition of the corrosion of N80 steel in 3.5 wt. % NaCl solution saturated with CO2 by four porphyrins, namely 5,10,15,20-tetrakis(4-hydroxyphenyl-21H,23H-porphyrin (HPTB, 5,10,15,20-tetra(4-pyridyl-21H,23H-porphyrin (T4PP, 4,4′,4″,4‴-(porphyrin-5,10,15,20-tetrayltetrakis(benzoic acid (THP and 5,10,15,20-tetraphenyl-21H,23H-porphyrin (TPP was studied using electrochemical impedance spectroscopy (EIS, potentiodynamic polarization, scanning electrochemical microscopy (SECM and scanning electron microscopy (SEM techniques. The results showed that the inhibition efficiency, η% increases with increasing concentration of the inhibitors. The EIS results revealed that the N80 steel surface with adsorbed porphyrins exhibited non-ideal capacitive behaviour with reduced charge transfer activity. Potentiodynamic polarization measurements indicated that the studied porphyrins acted as mixed type inhibitors. The SECM results confirmed the adsorption of the porphyrins on N80 steel thereby forming a relatively insulated surface. The SEM also confirmed the formation of protective films of the porphyrins on N80 steel surface thereby protecting the surface from direct acid attack. Quantum chemical calculations, quantitative structure activity relationship (QSAR were also carried out on the studied porphyrins and the results showed that the corrosion inhibition performances of the porphyrins could be related to their EHOMO, ELUMO, ω, and μ values. Monte Carlo simulation studies showed that THP has the highest adsorption energy, while T4PP has the least adsorption energy in agreement with the values of σ from quantum chemical calculations.

  8. Simulation of the beam guiding of the SAPHIR experiment by means of a differential-equation model; Simulation der Strahlfuehrung des SAPHIR-Experiments mittels eines Differentialgleichungsmodells

    Energy Technology Data Exchange (ETDEWEB)

    Greve, T.

    1991-08-01

    This paper shows the numerical simulation of a beam line by means of a model of differential equations simulating the beam line from the Bonn Electron Stretcher Accelerator ELSA to the SAPHIR spectrometer. Furthermore a method for calculating the initial values based on measurements of beam profiles is being discussed. (orig.). [Deutsch] Diese Arbeit zeigt die numerische Simulation einer Strahlfuehrung mittels eines Differentialgleichungsmodells anhand der Strahlfuehrung vom Bonner ELSA-Beschleuniger zum SAPHIR-Experiment. Weiterhin wird eine Methode zur Gewinnung der Startwerte aus Strahlprofilmessungen diskutiert. (orig.).

  9. 3D modeling of stratigraphic units and simulation of seismic facies in the Lion gulf margin; Modelisation 3D des unites stratigraphiques et simulation des facies sismiques dans la marge du golfe du Lion

    Energy Technology Data Exchange (ETDEWEB)

    Chihi, H.

    1997-05-12

    This work aims at providing a contribution to the studies carried out on reservoir characterization by use of seismic data. The study mainly consisted in the use of geostatistical methods in order to model the geometry of stratigraphic units of the Golfe du Lion margin and to simulate the seismic facies from high resolution seismic data. We propose, for the geometric modelling, a methodology based on the estimation of the surfaces and calculation afterwards of the thicknesses, if the modelling of the depth is possible. On the other hand the method consists in estimating the thickness variable directly and in deducing the boundary surfaces afterwards. In order to simulate the distribution of seismic facies within the units of the western domain, we used the truncated Gaussian method. The used approach gave a satisfactory results, when the seismic facies present slightly dipping reflectors with respect to the reference level. Otherwise the method reaches its limits because of the problems of definition of a reference level which allows to follow the clino-forms. In spite of these difficulties, this simulation allows us to estimate the distribution of seismic facies within the units and then to deduce their probable extension. (author) 150 refs.

  10. Aircraft Steels

    Science.gov (United States)

    2009-02-19

    component usage. PH 13-8Mo is a precipitation-hardenable martensitic stainless steel combining excellent corrosion resistance with strength. Custom 465 is...a martensitic , age-hardenable stainless steel capable of about 1,724 MPa (250 ksi) UTS when peak-aged (H900 condition). Especially, this steel can...NOTES 14. ABSTRACT Five high strength steels (4340, 300M, AerMet 100, Ferrium S53, and Hy-Tuf) and four stainless steels (High Nitrogen, 13

  11. Experimental study and numerical simulation of free pulsed jets; Etude experimentale et modelisation numerique des jets libres pulses

    Energy Technology Data Exchange (ETDEWEB)

    Marzouk, Salwa; Mhiri, Hatem [Ecole Nationale d' Ingenieurs de Monastir, Lab. de Mecanique des Fluides et Thermique, Monastir (Tunisia); Caminat, Ph.; Le Palec, G.; Bournot, Ph. [UNIMECA, 13 - Marseille (France)

    2001-07-01

    A plane pulsed jet flow has been simulated by a finite difference method. Experimental results have also been obtained by laser tomography and particle image velocimetry. The results show that the flow is affected by the pulsation in the vicinity of the nozzle to reach an asymptotic state of a permanent jet. (A.L.B.)

  12. Fatigue behavior of austenitic steels. Subproject. Mechanism oriented investigation of the fatigue behavior of austenitic steel X6CrNiNb1810 in the HCF and VHCF regime. Final report; Ermuedungsverhalten Austenit. Teilprojekt. Mechanismenorientierte Untersuchung des Ermuedungsverhaltens des austenitischen Stahles X6CrNiNb1810 im HCF- und VHCF-Bereich. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Sorich, A.; Smaga, M.; Eifler, D.

    2015-01-23

    In addition to load cycles in the Low Cycle Fatigue (LCF)-regime due to start up and shut down procedures of power plants, in some components additional high-frequency loadings in the High Cycle Fatigue (HCF)- and Very High Cycle Fatigue (VHCF)-regime occur. These loadings are induced e.g. by stresses due to thermal cyclic fluctuations and fluid dynamic processes. Therefore it is necessary to characterize experimentally the cyclic deformation behavior of metastable austenitic steels at operating temperature particularly in the HCF- and VHCF-regime and to develop a nondestructive method to detect fatigue processes. This joint research project was conducted in cooperation between the Institute of Materials Science and Engineering (WKK) of the University of Kaiserslautern and the Fraunhofer-Institute for Non-Destructive Testing (IZFP) in Saarbruecken. WKK was focused on experimental investigations to characterize the cyclic deformation behavior of the metastable austenitic steel in the HCF- and VHCF-range, taking into account cyclic hardening and softening processes and in particular to consider fatigue-induced changes in microstructure. The IZFP has focused on the development and application of a testing concept based on electromagnetic ultrasonic measurements. The isothermal cyclic deformation behavior of the metastable austenitic steel X6CrNiNb1810 (1.4550, AISI 347) at 300 C in the HCF-range is characterized by cyclic softening until specimen failure. At strain amplitudes of 0.10 % ≤ ε{sub a,t} ≤ 0.15 % and the stress amplitude σ{sub a} = 160 MPa cyclic softening is followed by cyclic hardening, which results in a significant increase in life time, up to the limiting number of cycles, which was defined at N{sub I} = 10{sup 7} in HCF-regime. The cyclic hardening is determined by a transformation induced phase formation from face-centered cubic (fcc) austenite to body-centered cubic (bcc) α{sup '}-martensite and/or in hexagonal (hcp) ε-martensite. In

  13. Effect of Welding Heat Input on the Microstructure and Toughness in Simulated CGHAZ of 800 MPa-Grade Steel for Hydropower Penstocks

    Directory of Open Access Journals (Sweden)

    Qingfeng Ding

    2017-03-01

    Full Text Available To determine the appropriate welding heat input for simulated coarse grained heat affected zone (CGHAZ of 800 MPa-grade steel used in hydropower penstocks, the microstructural evolution, hardness, and 50% fraction appearance transition temperature (50% FATT were investigated. The results indicated that when the cooling rate (heat input is reduced (increased, the impact toughness at −20 °C and hardness of the simulated CGHAZ decreased. When the heat input increased from 18 to 81 kJ/cm, the 50% FATT increased from −80 °C to −11 °C. At 18 kJ/cm, the microstructures consisted of lath bainite and granular bainite, but lath bainite decreased with increasing heat input. The increase in the 50% FATT was attributed mainly to an increase in the austenite grain size and effective grain size, and a decrease in lath bainite and the fraction of HAGBs (misorientation: ≥15°.

  14. Phase-field simulation of nucleation and growth of M{sub 23}C{sub 6} carbide and ferromagnetic phases during creep deformation in Type 304 steel

    Energy Technology Data Exchange (ETDEWEB)

    Tsukada, Yuhki, E-mail: tsukada@silky.numse.nagoya-u.ac.j [Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Shiraki, Atsuhiro; Murata, Yoshinori [Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Takaya, Shigeru [Japan Atomic Energy Agency, 4002 Narita-cho, O-arai-machi, Higashi-ibaraki-gun, Ibaraki 311-1393 (Japan); Koyama, Toshiyuki [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Morinaga, Masahiko [Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2010-06-15

    A phase-field method was applied to the simulation of simultaneous nucleation and growth of both M{sub 23}C{sub 6} carbide and ferromagnetic {alpha} phases during the creep process in Type 304 steel. Nucleation events of these product phases were explicitly introduced through a probabilistic Poisson seeding process based on local nucleation rates that were calculated as a function of local concentration. The defect energy of the creep dislocations near the carbides, which increases during creep, was integrated into the nucleation driving force for the {alpha} phase. The simulation used in this study accurately reproduced changes in the amounts of the precipitated phases as a function of creep time. Furthermore, we examine the effect of the dislocation density on precipitation of the {alpha} phase, and show that the phase-field method is useful for examining the stochastic and kinetic phenomenon of phase transformation.

  15. Computational simulation of the microstructure of irradiation damaged regions for the plate type fuel of UO2 microspheres dispersed in stainless steel matrix

    International Nuclear Information System (INIS)

    Reis, S.C. dos; Lage, A.F.; Braga, D.; Ferraz, W.B.

    2006-01-01

    Plate type fuel elements have high efficiency of thermal transference what benefits the heat flux with high rates of power output. In reactor cores, fuel elements, in general, are subject to a high neutrons flux, high working temperatures, severe corrosion conditions, direct interference of fission products that result from nuclear reactions and radiation interaction-matter. For plate type fuels composed of ceramic particles dispersed in metallic matrix, one can observe the damage regions that arise due to the interaction fission products in the metallic matrix. Aiming at evaluating the extension of the damage regions in function of the particles and its diameters, in this paper, computational geometric simulations structure of plate type fuel cores, composed of UO 2 microspheres dispersed in stainless steel in several fractions of volume and diameters were carried out. The results of the simulations were exported to AutoCAD R where it was possible its visualization and analysis. (author)

  16. Identification of the steel viscosity and dynamic yield stress for the numerical modelling of casting simulations in the semi-solid state

    Directory of Open Access Journals (Sweden)

    Solek K.

    2017-03-01

    Full Text Available Conditions of some casting processes cause flow of both liquid and semi-liquid metal alloys inside the die cavity. Generally, the continuous casting, squeeze casting or thixoforming could be classified as such processes. Design or optimisation of casting technology using numerical simulations requires knowledge of the rheological properties. The main objective of the experimental work, presented in this publication, is an analysis of the viscosity of 1.2080 (X210Cr12 high carbon steel in liquid and semisolid state. The secondary purpose of the experimental work was a development of the viscosity models used in continuous casting and thixoforming simulations. The significant achievement of this particular study was identification of thixotropy phenomenon which occurs not only during thixoforming, but also during magnetohydrodynamic stirring in continuous casting processes.

  17. Pore-Scale Flow Simulations: Model Predictions Compared with Experiments on Bi-Dispersed Granular Assemblies Simulation d’écoulements à l’échelle porale : comparaison des prédictions du modèle et d’expériences sur mélanges de billes de verre bi-disperses

    Directory of Open Access Journals (Sweden)

    Tong A.-T.

    2012-11-01

    Full Text Available A method is presented for the simulation of pore flow in granular materials. The numerical model uses a combination of the discrete element method for the solid phase and a novel finite volume formulation for the fluid phase. The solid is modeled as an assembly of spherical particles, where contact interactions are governed by elasto-plastic relations. Incompressible Stokes flow is considered, assuming that inertial forces are small in comparison with viscous forces. Pore geometry and pore connections are defined locally through regular triangulation of spheres, from which a tetrahedral mesh arises. The definition of pore-scale hydraulic conductivities is a key aspect of this model. In this sense, the model is similar to a pore-network model. Permeability measurements on bi-dispersed glass beads are reported and compared with model predictions, validating the definition of local conductivities. Une méthode est présentée pour la simulation de l’écoulement porale dans les matériaux granulaires. Le modèle numérique est basé sur la méthode des éléments discrets pour la phase solide et sur une nouvelle méthode de type volumes finis pour la phase fluide. Le solide est modélisé comme un arrangement de particules sphériques avec des interactions de type élasto-plastique aux contacts. On considère un écoulement de Stokes incompressible en supposant que les forces inertielles sont négligeables par rapport aux forces visqueuses. La géométrie des pores et leur connectivité sont définies sur la base d’une triangulation régulière des sphères qui aboutit à un maillage tétraédrique. La définition des conductivités hydrauliques à l’échelle des pores est un point clef du modèle qui se rapproche sur ce point à des modèles de type pore-network. Des mesures de perméabilités sur des assemblages bi-disperses de billes de verre sont présentées et comparées aux prédictions du modèle ce qui valide la définition des

  18. Considering heterogeneities by transmissibilities averaging on adapted meshes in reservoir simulation; Prise en compte des heterogeneites par prise de moyenne des transmissivites sur maillages adaptes en simulation de reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Urgelli, D

    1998-10-16

    Reservoir heterogeneity can be described using geostatistical models. But these models generate the heterogeneity on millions of fine grid blocks, which leads to prohibitive computational costs for reservoir simulations. In order to reduce the number of grid blocks, averaging techniques are needed to up-scale the fine scale permeabilities to the larger scales appropriate for flow simulation and engineering calculations. Grid block permeability up-scaling for numerical reservoir simulations has been discussed for a long time in the literature. It is now recognized that a full permeability tensor is needed to get an accurate reservoir description. But, the equivalent permeability on coarse grid blocks cannot be used directly on the numerical scheme. Usually, the harmonic average of the coarse grid block permeability is used for the transmissibility calculation, but it might cause a loss of accuracy. The purpose of this thesis is to present a new procedure for computing the equivalent transmissibility in the discretized flow equations on Cartesian grids and Corner Point Geometry grids. An application of this technique to a finite volume type numerical scheme is detailed. The principle of this technique is to calculate a permeability term on a shifted block placed between the two adjacent blocks where the transmissibility must be determined. At the field scale, the flow region can be divided into two types : a linear flow pattern with a low pressure gradient far from the wells and a radial flow pattern with a high pressure gradient in the vicinity of the wells. The radial flow region is usually more important for the prediction of production forecast, because it is directly related to the well. This was demonstrated theoretically and numerically for 2-D problem. The transmissibility up-scaling in radial flow pattern consists to determine the transmissibilities in the vicinity of wells and the numerical Productivity Index simultaneously. This new method called `shifted

  19. Numerical simulations of flows through fixed networks of monodispersed and bi-dispersed spheres, for moderate Reynolds numbers; Simulations numeriques d'ecoulements a travers des reseaux fixes de spheres monodisperses et bidisperses, pour des nombres de Reynolds moderes

    Energy Technology Data Exchange (ETDEWEB)

    Massol, A.

    2004-02-15

    The application of statistically averaged two-fluid models for the simulation of complex indus- trial two-phase flows requires the development of adequate models for the drag force exerted on the inclusions and the interfacial heat exchange. This task becomes problematic at high volume fractions of the dispersed phase. The quality of the simulation strongly depends upon the inter- facial exchange terms, starting with the steady drag force. For example, an accurate modelling of the drag force is therefore a crucial point to simulate the expansion of dense fluidized beds. Most models used to study the exchange terms between particles and fluids are based on the interaction between an isolated particle and a surrounding gas. Those models are clearly not adequate in cases where the volume fraction of particles increases and particle-particle interactions become important. Studying such cases is a complex task because of the multiple possible configurations. While the interaction between an isolated sphere and a gas depends only on the particle size and the slip velocity between gas and particles, the interaction between a cloud of particles and a gas depends on many more parameters: size and velocity distribution of particles, relative position of particles. Even if the particles keep relative fixed positions, there is an infinite number of combinations to construct such an array. The objective of the present work is to perform steady and unsteady simulations of the flow in regular arrays of fixed particles in order to analyze the influence of the size and distributions of spheres on drag force and heat transfer (the array of spheres can be either monodispersed, either bi-dispersed). Several authors have studied the drag exerted on the spheres, but only for low Reynolds numbers and/or solid volume fractions close to the packed limit. Moreover some discrepancies are observed between the different studies. On top of that, all existing studies are limited to steady flows

  20. X-ray Radiographic Study of Simulated Voids-like Defects in Al-Castings and Welded in Steel

    International Nuclear Information System (INIS)

    Mahrok, M.; Juma, Th.; Saeed, F.

    2013-01-01

    the detection and evaluation of imperfections in internal structures of casting and welded joints by x - ray radiography were studied.Optimum radiography conditions that improved the radiographic detection were attempted.Mathematical equations for radiography were used to calculate the size and depth of defects in casting were tested for validity to a wide range of parameters commonly used in radiography and for variable density and shape of the defects with respect to surrounding.Two kinds of samples are prepared.The first is aluminum casting through which two different sizes of a regular steel spheres are included and then radio graphed from two opposite sides to estimate their dimensional information from the radiographs.The second sample is steel plates which are welded and then radio graphed by x - rays.Imperfections such as incomplete root penetration, undercut and porosity were detected in the radiographs.

  1. Numerical simulation on temperature field of TIG welding for 0Cr18Ni10Ti steel cladding and experimental verification

    International Nuclear Information System (INIS)

    Luo Hongyi; Tang Xian; Luo Zhifu

    2015-01-01

    Aiming at tungsten inert gas (TIG) for 0Cr18Ni10Ti stainless steel cladding for radioactive source, the numerical calculation of welding pool temperature field was carried out through adopting ANSYS software. The numerical model of non-steady TIG welding pool shape was established, the heat enthalpy and Gaussian electric arc heat source model of surface distribution were introduced, and the effects of welding current and welding speed to temperature field distribution were calculated. Comparing the experimental data and the calculation results under different welding currents and speeds, the reliability and correctness of the model were proved. The welding technological parameters of 0Cr18Ni10Ti stainless steel were optimized based on the calculation results and the welding procedure was established. (authors)

  2. Analysis of the corrosion of carbon steels in simulated salt repository brines and acid chloride solutions at high temperatures

    International Nuclear Information System (INIS)

    Diercks, D.R.; Kassner, T.F.

    1988-04-01

    An analysis of literature data on the corrosion of carbon steels in anoxic brines and acid chloride solutions was performed, and the results were used to assess the expected life of high-level nuclear waste package containers in a salt repository environment. The corrosion rate of carbon steels in moderately acidic aqueous chloride environments obeys an Arrhenius dependence on temperature and a (pH 2 ) -1/2 dependence on hydrogen partial pressure. The cathodic reduction of water to produce hydrogen is the rate-controlling step in the corrosion process. An expression for the corrosion rate incorporating these two dependencies was used to estimate the corrosion life of several proposed waste package configurations. 42 refs., 11 figs., 2 tabs

  3. Modeling and Simulated Annealing Optimization of Surface Roughness in CO2 Laser Nitrogen Cutting of Stainless Steel

    OpenAIRE

    M. Madić; M. Radovanović; B. Nedić

    2013-01-01

    This paper presents a systematic methodology for empirical modeling and optimization of surface roughness in nitrogen, CO2 laser cutting of stainless steel . The surface roughness prediction model was developed in terms of laser power , cutting speed , assist gas pressure and focus position by using The artificial neural network ( ANN ) . To cover a wider range of laser cutting parameters and obtain an experimental database for the ANN model development, Taguchi 's L27 orthogonal array was im...

  4. Theory and simulation of ion acceleration with circularly polarized laser pulses; Theorie et simulation de l'acceleration des ions par impulsions laser a polarisation circulaire

    Energy Technology Data Exchange (ETDEWEB)

    Macchi, A. [CNR/INFM/polyLAB, Pisa (Italy); Macchi, A.; Tuveri, S.; Veghini, S. [Pisa Univ., Dept. of Physics E. Fermi (Italy); Liseikina, T.V. [Max Planck Institute for Nuclear Physics, Heidelberg (Germany)

    2009-03-15

    Ion acceleration driven by the radiation pressure of circularly polarized pulses is investigated via analytical modeling and particle-in-cell simulations. Both thick and thin targets, i.e. the 'hole boring' and 'light sail' regimes are considered. Parametric studies in one spatial dimension are used to determine the optimal thickness of thin targets and to address the effects of preformed plasma profiles and laser pulse ellipticity in thick targets. Three-dimensional (3D) simulations show that 'flat-top' radial profiles of the intensity are required to prevent early laser pulse breakthrough in thin targets. The 3D simulations are also used to address the issue of the conservation of the angular momentum of the laser pulse and its absorption in the plasma. (authors)

  5. Semiconductor device models for circuit simulation power electronics; Modeles de composants semiconducteurs pour la simulation des circuits en electronique de puissance

    Energy Technology Data Exchange (ETDEWEB)

    Berraies, M.O.

    1998-09-10

    In this thesis, an alternative strategy based on a regional approach to modeling and a new partition of the model library in the simulation is proposed. The main objective is to substitute for the usual concept of `one device, on model` that of an adaptable assembly of a limited number of submodels associated with well-identified regions of semiconductor structures. In other words, the library will only contain the primitive building-blocks of the power device models. This strategy guarantees the compatibility of the various semiconductor models in terms of physical concepts, validity domain, accuracy, homogeneity of parameter identification procedures, similarly of implementation in the simulator. This approach has been applied to PIN diodes and IGBTs for experimental validation. The next step consisted on the simulation of circuit involving several interacting devices. A simple IGBT/PIN diode chopper cell has been chosen. The results obtained compare well with experiment. This demonstrates the consistency of the proposed approach. (author) 43 refs.

  6. Support of the operation of an agricultural biogas plants with dynamic simulation; Unterstuetzung des Betriebs einer landwirtschaftlichen Biogasanlage mit dynamischer Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Seick, Ingolf; Gebhardt, Sebastian [Hochschule Magdeburg-Stendal, Magdeburg (Germany). Fachbereich Wasser- und Kreislaufwirtschaft; Tschepetzki, Ralf [ifak system GmbH, Magdeburg (Germany)

    2012-07-01

    Mathematical models for the dynamic simulation can be useful for agricultural biogas plants, but are not state of the art. Presented in the following text is a dynamic simulation model of a typical plant. This is based on the Anaerobic Digestion Model No. 1 (ADM1) and parameterized and compared with relevant system data. The results were incorporated into the development of a system for the direct, model-based operational support of biogas plants. Integrated is an operation diary for data acquisition and a simulation system. It supports the biogas plant operation through analysis and evaluation of complex biological processes, forecasting (e.g. the gas yield) and optimization of biology in conjunction with the process technology. Based on the above biogas plant, a practical method and exemplary results of an automatic model adjustment will be shown and example forecasts for the stabilization of the biological process are presented. (orig.)

  7. Numerical simulation of the roll levelling of third generation fortiform 1050 steel using a nonlinear combined hardening material model

    Science.gov (United States)

    Galdos, L.; Saenz de Argandoña, E.; Mendiguren, J.; Silvestre, E.

    2017-09-01

    The roll levelling is a flattening process used to remove the residual stresses and imperfections of metal strips by means of plastic deformations. During the process, the metal sheet is subjected to cyclic tension-compression deformations leading to a flat product. The process is especially important to avoid final geometrical errors when coils are cold formed or when thick plates are cut by laser. In the last years, and due to the appearance of high strength materials such as Ultra High Strength Steels, machine design engineers are demanding reliable tools for the dimensioning of the levelling facilities. Like in other metal forming fields, finite element analysis seems to be the most widely used solution to understand the occurring phenomena and to calculate the processing loads. In this paper, the roll levelling process of the third generation Fortiform 1050 steel is numerically analysed. The process has been studied using the MSC MARC software and two different material laws. A pure isotropic hardening law has been used and set as the baseline study. In the second part, tension-compression tests have been carried out to analyse the cyclic behaviour of the steel. With the obtained data, a new material model using a combined isotropic-kinematic hardening formulation has been fitted. Finally, the influence of the material model in the numerical results has been analysed by comparing a pure isotropic model and the later combined mixed hardening model.

  8. Non-analogue Monte Carlo method, application to neutron simulation; Methode de Monte Carlo non analogue, application a la simulation des neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Morillon, B.

    1996-12-31

    With most of the traditional and contemporary techniques, it is still impossible to solve the transport equation if one takes into account a fully detailed geometry and if one studies precisely the interactions between particles and matters. Only the Monte Carlo method offers such a possibility. However with significant attenuation, the natural simulation remains inefficient: it becomes necessary to use biasing techniques where the solution of the adjoint transport equation is essential. The Monte Carlo code Tripoli has been using such techniques successfully for a long time with different approximate adjoint solutions: these methods require from the user to find out some parameters. If this parameters are not optimal or nearly optimal, the biases simulations may bring about small figures of merit. This paper presents a description of the most important biasing techniques of the Monte Carlo code Tripoli ; then we show how to calculate the importance function for general geometry with multigroup cases. We present a completely automatic biasing technique where the parameters of the biased simulation are deduced from the solution of the adjoint transport equation calculated by collision probabilities. In this study we shall estimate the importance function through collision probabilities method and we shall evaluate its possibilities thanks to a Monte Carlo calculation. We compare different biased simulations with the importance function calculated by collision probabilities for one-group and multigroup problems. We have run simulations with new biasing method for one-group transport problems with isotropic shocks and for multigroup problems with anisotropic shocks. The results show that for the one-group and homogeneous geometry transport problems the method is quite optimal without splitting and russian roulette technique but for the multigroup and heterogeneous X-Y geometry ones the figures of merit are higher if we add splitting and russian roulette technique.

  9. Influence of sulphate ions on the composition and structure of the oxide films on stainless steel and nickel alloys in simulated BWR crack conditions

    International Nuclear Information System (INIS)

    Bojinov, M.; Kinnunen, P.; Laitinen, E.; Maekelae, K.; Saario, T.; Sirkiae, P.; Toivonen, A.; Campbell, J.M.; Johansson, L.S.; Helin, M.; Muttilainen, E.; Reinvall, A.; Ollonqvist, T.; Vaeyrynen, J.

    2002-01-01

    The goal of the present work has been to clarify the influence of sulphate ions on the oxide films formed on stainless steel and Ni-based alloys in simulated crack chemistry conditions using different ex situ analytical techniques. The main observations of this work can be summarised as follows: The thickness of the films formed in simulated oxygen-free crack chemistry conditions during an exposure of circa 4 days varies roughly in the range 200..500 nm, which corresponds to observations reported in the literature [2]. The presence of 10000 ppb sulphate ions in simulated crack tip conditions seems to lead to a considerably lower thickness of the oxide films when compared to sulphate-free conditions. The presence of 10000 ppb sulphate ions leads also to considerable changes in the morphology of the oxide crystals on the material samples. In the absence of sulphate the outer oxide layer contains elongated round-edged crystals, while in the presence of sulphate ions the crystals are longish and needle-like. No visible difference can be observed in the outlook of the crystals formed on stainless steel and Inconel alloy surfaces. A small amount of sulphur in the form of sulphate can be found on the oxide surface on all the studied materials after exposure to the 10000 ppb solution. Sulphur seems to become incorporated inside the oxide film on AISI 316 L(NG). It is not clear at this stage, whether the observed influence of the sulphate ions can be ascribed to the lower pH, to a possible effect on solubility or to a direct influence of the anionic species. (authors)

  10. Environmental effects on fatigue of steels for structural parts in water-steam-circuits of light water reactors. Considerations concerning the question of transferability of results from laboratory tests to real operating conditions; Der Einfluss des Mediums auf Ermuedungsvorgaenge in Staehlen fuer Strukturbauteile in Wasser-Dampf-Kreislaeufen von Leichtwasserreaktoren. Ueberlegungen zur Frage der Uebertragbarkeit von Ergebnissen aus Laborversuchen auf den realen Anlagenbetrieb

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Armin [AREVA NP GmbH, Erlangen (Germany)

    2008-07-01

    Based on material science and physical chemistry it seems plausible that a corrosive medium can influence the fatigue behaviour of structural materials, i.e. steels. It has been shown decades before that high temperature water has significant effects on the fatigue behaviour of steels, decreasing the crack initiation time or increasing the growth rate of existing cracks. At the beginning of nuclear regulations this expected influence of the medium on fatigue of components of nuclear power plants was worldwide not accounted for in the relevant standards (for instance ASME Boiler and Pressure Vessel Code, section III). There was a general consideration of medium effects on the da/dN crack growth curves in the ASME Code, section XI for the assessment of the surface flaw behaviour during operation. Historically, these regulations were implemented long before the experimental observation of medium effects on crack initiation and crack growth during fatigue of steels in high-temperature water. Besides this fact there have been worldwide no generic, systematic damages of medium containing components in light-water reactors due to corrosion fatigue. Singular damages with significant medium influenced fatigue features could always be explained by not specified operational transients, like thermal stratification or local flow-induced vibrations. The contribution provides considerations that explain the discrepancy between to worldwide positive operational experience and the definitive experimental indication of a medium-enhanced fatigue. Based on these considerations the author scrutinizes critically the US NRC Regulatory Guide 1.207 with respect to the medium influence on the component's fatigue behaviour. Possibilities for experimental assessment of the discussed hypothesis are shown. [German] Es erscheint aus werkstoffkundlichen und physikalisch-chemischen Gruenden grundsaetzlich plausibel, dass ein korrosives Medium das Ermuedungsverhalten von Strukturwerkstoffen, z

  11. FE-simulation of the viscoplastic behaviour of different RPV steels in the frame of in-vessel melt retentions scenarios

    International Nuclear Information System (INIS)

    Altstadt, E.; Willschuetz, H.G.; Mueller, G.

    2004-01-01

    Assuming the hypothetical scenario of a severe accident with subsequent core meltdown and formation of a melt pool in the reactor pressure vessel (RPV) lower plenum of a Light Water Reactor (LWR) leads to the question about the behavior of the RPV. One accident management strategy could be to stabilize the in-vessel debris configuration in the RPV as one major barrier against uncontrolled release of heat and radio nuclides. To get an improved understanding and knowledge of the melt pool convection and the vessel creep and possible failure processes and modes occurring during the late phase of a core melt down accident the FOREVER-experiments (Failure Of REactor VEssel Retention) have been performed at the Division of Nuclear Power Safety of the Royal Institute of Technology Stockholm. These experiments are simulating the behavior of the lower head of the RPV under the thermal loads of a convecting melt pool with decay heating, and under the pressure loads that the vessel experiences in a depressurization scenario. The geometrical scale of the experiments is 1:10 compared to a common LWR. This paper deals with the experimental, numerical, and metallographical results of the creep failure experiment EC-FOREVER-4, where the American pressure vessel steel SA533B was applied for the lower head. For comparison the results of the experiment EC-FOREVER-3B, build of the French 16MND5 steel, are discussed, too. Emphasis is put on the differences in the viscoplastic behaviour of different heats of the RPV steel. For this purpose, the creep tests in the frame of the LHF/OLHF experiments are reviewed, too. As a hypothesis it is stated that the sulphur content could be responsible for differences in the creep behaviour. (orig.)

  12. Influence of localized deformation on A-286 austenitic stainless steel stress corrosion cracking in PWR primary water; Influence de la localisation de la deformation sur la corrosion sous contrainte de l'acier inoxydable austenitique A-286 en milieu primaire des REP

    Energy Technology Data Exchange (ETDEWEB)

    Savoie, M

    2007-01-15

    Irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels is known to be a critical issue for structural components of nuclear reactor cores. The deformation of irradiated austenitic stainless steels is extremely heterogeneous and localized in deformation bands that may play a significant role in IASCC. In this study, an original approach is proposed to determine the influence of localized deformation on austenitic stainless steels SCC in simulated PWR primary water. The approach consists in (i) performing low cycle fatigue tests on austenitic stainless steel A-286 strengthened by {gamma}' precipitates Ni{sub 3}(Ti,Al) in order to shear and dissolve the precipitates in intense slip bands, leading to a localization of the deformation within and in (ii) assessing the influence of these {gamma}'-free localized deformation bands on A-286 SCC by means of comparative CERT tests performed on specimens with similar yield strength, containing or not {gamma}'-free localized deformation bands. Results show that strain localization significantly promotes A-286 SCC in simulated PWR primary water at 320 and 360 C. Moreover, A-286 is a precipitation-hardening austenitic stainless steel used for applications in light water reactors. The second objective of this work is to gain insights into the influence of heat treatment and metallurgical structure on A-286 SCC susceptibility in PWR primary water. The results obtained demonstrate a strong correlation between yield strength and SCC susceptibility of A-286 in PWR primary water at 320 and 360 C. (author)

  13. Brake hydraulics simulation with real-time capability. From hydraulics plan to implementation: the Bosch ESP 5.7 as an example; Echtzeitfaehige Bremshydrauliksimulation. Vom Hydraulikplan zur Implementierung am Beispiel des Bosch ESP 5.7

    Energy Technology Data Exchange (ETDEWEB)

    Marc, E.; Oliver, P.; Thies, W. [Tesis Dynaware (Germany)

    2001-11-01

    For the development and testing of ABS/ESP control units, both the detailed simulation of the vehicle and drive train dynamics as well as the dynamic behaviour of the hydraulic system are important. The signals coming from the control unit that control the valves in the brake hydraulic system cause pressure changes in the brake system and thus affect the braking torque. In turn, the changes in the speed of the wheels are fed back to the control unit via sensors. The objective of an ABS control strategy is to prevent the wheels from locking during braking in order to ensure and maintain the steerability of the vehicle, while the ESP action also attempts to achieve a stabilization of the yawing motion by means of active braking. (orig.) [German] Fuer die Entwicklung und den Test von ABS/ESP-Steuergeraeten ist neben der detaillierten Simulation von Fahr- und Antriebsstrangdynamik auch das dynamische Verhalten des hydraulischen Systems wichtig. Die vom Steuergeraet kommenden Signale zur Ansteuerung der Ventile in der Bremshydraulik bewirken Druckaenderungen im Bremssystem und somit der Bremsmomente. Die Aenderungen der Raddrehzahlen werden wiederum ueber Sensoren dem Steuergeraet zurueckgemeldet. Ziel einer ABS-Regelstrategie ist das Verhindern des Blockierens der Raeder beim Bremsen, um die Lenkbarkeit des Fahrzeugs zu erhalten, waehrend bei einem ESP-Eingriff durch aktives Bremsen zusaetzlich eine Stabilisierung der Gierbewegung erfolgen soll, wie der folgende Beitrag von Tesis Dynaware zeigt. (orig.)

  14. Cronos 2: a neutronic simulation software for reactor core calculations; Cronos 2: un logiciel de simulation neutronique des coeurs de reacteurs

    Energy Technology Data Exchange (ETDEWEB)

    Lautard, J J; Magnaud, C; Moreau, F; Baudron, A M [CEA Saclay, Dept. de Mecanique et de Technologie (DMT/SERMA), 91 - Gif-sur-Yvette (France)

    1999-07-01

    The CRONOS2 software is that part of the SAPHYR code system dedicated to neutronic core calculations. CRONOS2 is a powerful tool for reactor design, fuel management and safety studies. Its modular structure and great flexibility make CRONOS2 an unique simulation tool for research and development for a wide variety of reactor systems. CRONOS2 is a versatile tool that covers a large range of applications from very fast calculations used in training simulators to time and memory consuming reference calculations needed to understand complex physical phenomena. CRONOS2 has a procedure library named CPROC that allows the user to create its own application environment fitted to a specific industrial use. (authors)

  15. Building A Simulation Model For The Prediction Of Temperature Distribution In Pulsed Laser Spot Welding Of Dissimilar Low Carbon Steel 1020 To Aluminum Alloy 6061

    International Nuclear Information System (INIS)

    Yousef, Adel K. M.; Taha, Ziad A.; Shehab, Abeer A.

    2011-01-01

    This paper describes the development of a computer model used to analyze the heat flow during pulsed Nd: YAG laser spot welding of dissimilar metal; low carbon steel (1020) to aluminum alloy (6061). The model is built using ANSYS FLUENT 3.6 software where almost all the environments simulated to be similar to the experimental environments. A simulation analysis was implemented based on conduction heat transfer out of the key hole where no melting occurs. The effect of laser power and pulse duration was studied.Three peak powers 1, 1.66 and 2.5 kW were varied during pulsed laser spot welding (keeping the energy constant), also the effect of two pulse durations 4 and 8 ms (with constant peak power), on the transient temperature distribution and weld pool dimension were predicated using the present simulation. It was found that the present simulation model can give an indication for choosing the suitable laser parameters (i.e. pulse durations, peak power and interaction time required) during pulsed laser spot welding of dissimilar metals.

  16. Simulation of lung motions using an artificial neural network; Utilisation d'un reseau de neurones artificiels pour la simulation des mouvements pulmonaires

    Energy Technology Data Exchange (ETDEWEB)

    Laurent, R.; Henriet, J.; Sauget, M.; Gschwind, R.; Makovicka, L. [IRMA/ENISYS/FEMTO-ST, UMR 6174 CNRS, pole universitaire des Portes du Jura, BP 71427, 25211 Montbeliard cedex (France); Salomon, M. [AND/LIFC, universite de Franche-Comte, BP 527, rue Engel-Gros, 90016 Belfort cedex (France); Nguyen, F. [Service de radiotherapie, CHU Jean-Minjoz, 3, boulevard Fleming, 25030 Besancon cedex (France)

    2011-04-15

    Purpose. A way to improve the accuracy of lung radiotherapy for a patient is to get a better understanding of its lung motion. Indeed, thanks to this knowledge it becomes possible to follow the displacements of the clinical target volume (CTV) induced by the lung breathing. This paper presents a feasibility study of an original method to simulate the positions of points in patient's lung at all breathing phases. Patients and methods. This method, based on an artificial neural network, allowed learning the lung motion on real cases and then to simulate it for new patients for which only the beginning and the end breathing data are known. The neural network learning set is made up of more than 600 points. These points, shared out on three patients and gathered on a specific lung area, were plotted by a MD. Results. - The first results are promising: an average accuracy of 1 mm is obtained for a spatial resolution of 1 x 1 x 2.5 mm{sup 3}. Conclusion. We have demonstrated that it is possible to simulate lung motion with accuracy using an artificial neural network. As future work we plan to improve the accuracy of our method with the addition of new patient data and a coverage of the whole lungs. (authors)

  17. Steel making

    CERN Document Server

    Chakrabarti, A K

    2014-01-01

    "Steel Making" is designed to give students a strong grounding in the theory and state-of-the-art practice of production of steels. This book is primarily focused to meet the needs of undergraduate metallurgical students and candidates for associate membership examinations of professional bodies (AMIIM, AMIE). Besides, for all engineering professionals working in steel plants who need to understand the basic principles of steel making, the text provides a sound introduction to the subject.Beginning with a brief introduction to the historical perspective and current status of steel making together with the reasons for obsolescence of Bessemer converter and open hearth processes, the book moves on to: elaborate the physiochemical principles involved in steel making; explain the operational principles and practices of the modern processes of primary steel making (LD converter, Q-BOP process, and electric furnace process); provide a summary of the developments in secondary refining of steels; discuss principles a...

  18. New modelling method for fast reactor neutronic behaviours analysis; Nouvelles methodes de modelisation neutronique des reacteurs rapides de quatrieme Generation

    Energy Technology Data Exchange (ETDEWEB)

    Jacquet, P.

    2011-05-23

    Due to safety rules running on fourth generation reactors' core development, neutronics simulation tools have to be as accurate as never before. First part of this report enumerates every step of fast reactor's neutronics simulation implemented in current reference code: ECCO. Considering the field of fast reactors that meet criteria of fourth generation, ability of models to describe self-shielding phenomenon, to simulate neutrons leakage in a lattice of fuel assemblies and to produce representative macroscopic sections is evaluated. The second part of this thesis is dedicated to the simulation of fast reactors' core with steel reflector. These require the development of advanced methods of condensation and homogenization. Several methods are proposed and compared on a typical case: the ZONA2B core of MASURCA reactor. (author) [French] Les criteres de surete qui regissent le developpement de coeurs de reacteurs de quatrieme generation implique l'usage d'outils de calcul neutronique performants. Une premiere partie de la these reprend toutes les etapes de modelisation neutronique des reacteurs rapides actuellement d'usage dans le code de reference ECCO. La capacite des modeles a decrire le phenomene d'autoprotection, a representer les fuites neutroniques au niveau d'un reseau d'assemblages combustibles et a generer des sections macroscopiques representatives est appreciee sur le domaine des reacteurs rapides innovants respectant les criteres de quatrieme generation. La deuxieme partie de ce memoire se consacre a la modelisation des coeurs rapides avec reflecteur acier. Ces derniers necessitent le developpement de methodes avancees de condensation et d'homogenisation. Plusieurs methodes sont proposees et confrontees sur un probleme de modelisation typique: le coeur ZONA2B du reacteur maquette MASURCA

  19. Simulation of the hot flow behaviour of a medium carbon microalloyed steel. Part 2. Dynamic recrystallization: onset and kinetics

    International Nuclear Information System (INIS)

    Cabrera, J.M.; Al Omar, A.; Prado, J.M.

    1997-01-01

    According to the part 1 of this work, in this second part the dynamic recrystallization of a commercial medium carbon microalloyed steel is characterized from the point of view of its onset and kinetics. For this purpose uniaxial hot compression tests were carried out over a range of five orders of magnitude in strain rate and 300 degree centigree of temperature. Experimental results are compared with those reported in the literature and the possible effect of dynamic precipitation is also analyzed. It is verified that the kinetics of dynamics recrystallization can balefully be described by the classical Avrami equation. (Author) 42 refs

  20. The effect of gamma radiation on reference electrodes and platinum and carbon steel bare metal electrodes in a simulated waste solution

    International Nuclear Information System (INIS)

    Danielson, M.J.

    1993-09-01

    Electrochemical potential measurements of materials in waste tanks are important in determining if the materials have a propensity for stress corrosion cracking and pitting. Potential measurement requires a reference electrode, but the effect of radiation on the potential generated by the reference electrode has been an unknown quantity. To determine the significance of the radiation effect, Pacific Northwest Laboratory conducted studies of five types of electrodes under gamma radiation at room temperature. The subjects were two types of silver/silver chloride reference electrodes (Fisher and Lazaran), a mercury/calomel reference electrode, a platinum ''flag,'' and a piece of A-537 carbon steel; the electrodes were exposed to a simulated caustic tank environment. The Fisher silver/silver chloride and mercury/calomel reference electrodes showed essentially no radiation effects up to a flux of 2.1E6 R/h and fluence of 9.4E8 R, indicating they would be useful reference electrodes for in-tank studies. The Lazaran reg-sign silver/silver chloride electrode showed serious potential deviations at fluences of 2.E8 R, but it would be the electrode of choice in many situations because it is simple to maintain. Radiation affected the open circuit potential of both the platinum and carbon steel electrodes. This effect indicates that corrosion studies without radiation may not duplicate the corrosion processes expected in a waste tank. Mixed-potential theory was used to explain the radiation effects

  1. The influence of ppb levels of chloride impurities on the stress corrosion crack growth behaviour of low-alloy steels under simulated boiling water reactor conditions

    International Nuclear Information System (INIS)

    Seifert, H.P.; Ritter, S.

    2016-01-01

    Highlights: • Chloride effects on SCC crack growth in RPV steels under boiling water reactor conditions. • ppb-levels of chloride may result in fast SCC in normal water chemistry environment. • Much higher chloride tolerance for SCC in hydrogen water chemistry environment. • Potential long-term (memory) effects after severe and prolonged temporary chloride transients. - Abstract: The effect of chloride on the stress corrosion crack (SCC) growth behaviour in low-alloy reactor pressure vessel steels was evaluated under simulated boiling water reactor conditions. In normal water chemistry environment, ppb-levels of chloride may result in fast SCC after rather short incubation periods of few hours. After moderate and short-term chloride transients, the SCC crack growth rates return to the same very low high-purity water values within few 100 h. Potential long-term (memory) effects on SCC crack growth cannot be excluded after severe and prolonged chloride transients. The chloride tolerance for SCC in hydrogen water chemistry environment is much higher.

  2. Characterization of oxide film layers formed on A106 B carbon steel in simulated secondary coolant conditions of nuclear power plants

    International Nuclear Information System (INIS)

    Strack, M.; Bordoni, R.; Chocron, M.; Olmedo, A.M.; Zampieri, G.

    2011-01-01

    The water chemistry of the secondary coolant in the majority Nuclear Power Plants is controlled by AVT (All Volatile Treatment) procedure, wherein volatile amines are use to maintain the alkaline pH required for minimizing the corrosion of structural materials which one of them is Carbon Steel. In this procedure: hydrazine, morpholine and ethanolamine are used commonly as conditioning reagents. In this context, experiments were carried out by exposing carbon steel A106 B samples in a simulated secondary coolant in order to study the nature of the oxide films. The tests were performed in a static autoclave at 260 ºC using two media: 1) Hydrazine + morpholine and 2) Hydrazine + ethanolamine during different exposure periods up to ≈1020 h. The composition, surface morphology, X-ray diffraction, a chemical descaling procedure were used- XPS, was also employed, to analyze the films grown during ≈1020 h in both media. The characterization showed that magnetite was the main corrosion product formed in the films grown in the two media. The material weight loss (W) could be fitted by a law of the type W = k t n , up to 1020 h of exposure, resulting in n =0,42, k = 6,24 for films grown in medium 1) and n = 0,39, k =6,08 for films grown in medium 2); where W is in mg/d m 2 and t in h. (author) [es

  3. AFM study of microbial colonization and its deleterious effect on 304 stainless steel by Pseudomonas NCIMB 2021 and Desulfovibrio desulfuricans in simulated seawater

    International Nuclear Information System (INIS)

    Yuan, S.J.; Pehkonen, S.O.

    2009-01-01

    The biofilm colonization dynamics of Pseudomonas NCIMB 2021 and Desulfovibrio desulfuricans (ATCC 27774) on 304 stainless steels (304 SS) was evaluated using atomic force microscopy (AFM) in simulated seawater-based media under aerobic and anaerobic conditions. Results showed that the biofilm formed on the coupon surface by the two strains of bacteria increased in the coverage, heterogeneity and thickness with exposure time, thus resulting in the deterioration of the steel substratum underneath the biofilm in the form of pitting corrosion. The depth of pits induced by D. desulfuricans was larger than that by Pseudomonas NCIMB 2021, which was mainly attributed to the enhanced corrosion of 304 SS coupons by the biogenic sulfide ions, as revealed by the results of X-ray photoelectron spectroscopy (XPS) and Tafel polarization curves. AFM was also used to determine cell attachment/detachment processes of the Pseudomonas and D. desulfuricans bacteria on the coupon surface by quantifying the tip-cell interaction forces. The interactive forces between the tip and the bacterial cell surface were considerably smaller than those between the tip and the cell-cell interface due to the accumulation of extra-cellular polymeric substances (EPS) for both strains. Furthermore, the adhesion forces over the Pseudomonas cells were verified to be more attractive than those of D. desulfuricans due to the former being a slime-producer.

  4. Microstructure, state of internal stress and corrosion resistance of the short-time laser heat-treated nitrogen high-alloyed tool steel X30CrMoN151; Mikrostruktur, Eigenspannungszustand und Korrosionsbestaendigkeit des kurzzeitlaserwaermebehandelten hochstickstofflegierten Werkzeugstahls X30CrMoN151

    Energy Technology Data Exchange (ETDEWEB)

    Bohne, C. (ed.)

    2000-07-01

    This study compares the crystalline structure, state of internal stress and chemical properties of the high-alloyed nitrogen tool steel X30CrMoN15 1 and conventional cold work steel X39CrMo17 1. Transformation points A{sub c}1b and A{sub c}1e were calculated from residual austenite analysis and the c{sub m}/a{sub m} martensite ratios for various heating rates. This was used to generate a TTA (time-temperature-austenitisation) graph for X30CrMoN15 1 for the first time. Transmission electron microscopy and small-angle neutron scattering show that precipitates in nitrogen high-alloyed steel X30CrMoN15 1 can be eliminated completely by short-time laser heat treatment. The corrosion tests show that in contrast to X39CrMo17 1 X30CrMoN15 1 reacts more sensitively to parameter changes during short-time heat treatment in oxidising acid at pH 5-6. [German] Im Rahmen der Arbeit werden die Gefuegeausbildung, Eigenspannungen und chemische Eigenschaften des hochstickstofflegierten Werkzeugstahls X30CrMoN15 1 und des konventionellen Kaltarbeitsstahls X39CrMo17 1 verglichen. Aus den Restaustenitanalysen und den c{sub m}/a{sub m}-Verhaeltnissen des Martensits konnten die Umwandlungspunkte A{sub c1b} und A{sub c1e} fuer verschiedene Aufheizraten bestimmt und daraus ein bisher nicht bekanntes ZTA-Schaubild fuer den X30CrMoN15 1 erstellt werden. Transmissionselektronenmikroskopie und Neutronenkleinwinkelstreuung zeigen, dass sich die Ausscheidungen im hochstickstofflegierten Stahl X30CrMoN14 1 durch die Kurzzeitlaserwaermebehandlung vollstaendig aufloesen koennen. Die Korrosionsversuche zeigen, dass im Gegensatz zum X39CrMo17 1 der X30CrMoN15 1 in oxidierender Saeure bei pH 5-6 empfindlicher auf Parameteraenderungen bei der Kurzzeitwaermebehandlung reagiert. (orig.)

  5. Modelisation, conception et simulation des performances d'un collecteur solaire aeraulique a tubes sous vide en milieu nordique

    Science.gov (United States)

    Paradis, Pierre-Luc

    The global energy consumption is still increasing year after year even if different initiatives are set up to decrease fossil fuel dependency. In Canada 80% of the energy is used for space heating and domestic hot water heating in residential sector. This heat could be provided by solar thermal technologies despite few difficulties originating from the cold climate. The aim of this project is to design a solar evacuated tube thermal collector using air as the working fluid. Firstly, needs and specifications of the product are established in a clear way. Then, three concepts of collector are presented. The first one relies on the standard evacuated tube. The second one uses a new technology of tubes; both sides are open. The third one uses heat pipe to extract the heat from the tubes. Based on the needs and specification as criteria, the concept involving tubes with both sides open has been selected as the best idea. In order to simulate the performances of the collector, a model of the heat exchanges in an evacuated tube was developed in 4 steps. The first step is a model in steady state intended to calculate the stagnation temperature of the tube for a fixed solar radiation, outside temperature and wind speed. As a second step, the model is generalised to transient condition in order to validate it with an experimental setup. A root mean square error of 2% is then calculated. The two remainder steps are intended to calculate the temperature of airflow leaving the tube. In the same way, a first model in steady state is developed and then generalised to the transient mode. Then, the validation with an experimental setup gave a difference of 0.2% for the root mean square error. Finally, a preindustrial prototype intended to work in open loop for preheating of fresh air is presented. During the project, explosion of the both sides open evacuated tube in overheating condition blocked the construction of a real prototype for the test. Different path for further work are

  6. EMC behaviour modelling and simulation of components of the electric drivetrain; EMV-Verhaltensmodellierung und Simulation von Komponenten des elektrischen Antriebsstrangs

    Energy Technology Data Exchange (ETDEWEB)

    Frei, Stephan; Kremer, Frank [Technische Univ. Dortmund (Germany). Arbeitsgebiet Bordsysteme; Haase, Joachim [Fraunhofer-Institut fuer Integrierte Schaltungen, Dresden (Germany). Bereich Entwurfsautomatisierung; Hessel, Ewald [Hella KGaA Hueck und Co, Lippstadt (Germany)

    2013-03-15

    The introduction of high-voltage on-board electrical systems and high pulsed electric power in the drivetrain tends to lead to higher levels of interference in electromagnetic compatibility (EMC), and managing this requires appropriate counter-measures to be taken. Research currently being carried out by TU Dortmund University, Hella and the Fraunhofer Institute for Integrated Circuits II S in Dresden is focusing on EMC-compliant function development. Modelling and simulation can help to identify potential problems at an early stage.

  7. Modeling and simulation of the effective behaviour of interfaces in alloys; Modellierung und Simulation des effektiven Verhaltens von Grenzflaechen in Metalllegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Lenz, M.

    2007-07-15

    This thesis is concerned with the modeling and the numerical simulation of phase transitions during the Ostwald ripening of metal alloys and in magnetic shape memory materials. The phase transition is modeled on a continuum level with methods of elasticity theory. The coarsening of particles in a metal alloy after spinodal decomposition can be seen as a gradient flow: The set of particles moves on the manifold of all possible particle configurations in the direction of steepest descent of an energy functional containing interface energy and elasticity, with respect to a metric tensor describing the diffusion mechanism. The restriction of this evolution onto the submanifold of rectangular particles aligned to the coordinate axes, as they are preferred by the anisotropy of the elasticity tensor, gives a reduced model that describes the evolution of such particles. The numerical simulation of both models employs the boundary element method. The integral operators occurring are approximated by hierarchical matrices, this approximation also gives an appropriate preconditioner. To avoid the coupling of the time step size to the side length of the smallest particle, one uses localized timesteps close to small particles, where the screening effect makes it possible to restrict to small neighbourhoods of the respective particle. In this way one constructs an efficient method to simulate both models; in the reduced model accordingly the simulation of larger particle ensembles is possible. Comparative computations verify that the reduced model reproduces many important qualitative and quantitative properties of the full model. Magnetic shape memory materials can be modeled on a continuum scale using a combination of elasticity and micromagnetism. Here, a discrete phase parameter couples the variants of the elastic strain to the magnetic anisotropy. The anisotropy prefers a magnetization in the direction of contraction. This model can be applied to the description of several

  8. Fretting fatigue behaviour of Ni-free high-nitrogen stainless steel in a simulated body fluid

    Directory of Open Access Journals (Sweden)

    Norio Maruyama, Sachiko Hiromoto, Eiji Akiyama and Morihiko Nakamura

    2013-01-01

    Full Text Available Fretting fatigue behaviour of Ni-free high-nitrogen steel (HNS with a yield strength of about 800 MPa, which was prepared by nitrogen gas pressurized electroslag remelting, was studied in air and in phosphate-buffered saline (PBS(-. For comparison, fretting fatigue behaviour of cold-rolled SUS316L steel (SUS316L(CR with similar yield strength was examined. The plain fatigue limit of HNS was slightly lower than that of SUS316L(CR although the former had a higher tensile strength than the latter. The fretting fatigue limit of HNS was higher than that of SUS316L(CR both in air and in PBS(-. A decrease in fatigue limit of HNS by fretting was significantly smaller than that of SUS316L(CR in both environments, indicating that HNS has better fretting fatigue resistance than SUS316L(CR. The decrease in fatigue limit by fretting is discussed taking into account the effect of friction stress due to fretting and the additional influences of wear, tribocorrosion and plastic deformation in the fretted area.

  9. SIMULATION ET MODELISATION DE LA VARIATION DE LA MOBILITE DE HALL DES PHOTOELECTRONS EN FONCTION DE LA TEMPERATURE DANS LES CRISTAUX DE n-ZnSe :Zn IRRADIES AVEC DES ELECTRONS ENERGETIQUES

    Directory of Open Access Journals (Sweden)

    D DJOUADI

    2007-12-01

    Full Text Available Dans l’intervalle de températures [77..300 K] a été mesurée la mobilité de Hall des électrons d’équilibre et des photoélectrons dans les cristaux de n-ZnSe :Zn irradiés avec un faisceau d’électrons d’énergie E=1,3 MeV et dont la dose d’irradiation varie entre 2,73 1016 et 5.19 1017 électrons/cm2 . Le comportement de la mobilité des photoélectrons s’explique parfaitement dans le cadre d’un modèle à deux-barrières d’un semi-conducteur inhomogène représentant une matrice faiblement ohmique contenant des inclusions fortement ohmiques (clusters. En se basant sur les théories de Shik et de Petrossiyan , une expression approximative de la mobilité de Hall a été obtenue. Il a été montré que ce modèle fonctionne parfaitement pour les petites doses d’irradiation. Lorsque la dose dépasse une certaine valeur critique ( D= 2.98 1017 électrons /cm2 le modèle considéré passe au modèle du potentiel à relief aléatoire.

  10. Modelling and numerical simulation of liquid-vapor phase transitions; Modelisation et simulation numerique des transitions de phase liquide-vapeur

    Energy Technology Data Exchange (ETDEWEB)

    Caro, F

    2004-11-15

    This work deals with the modelling and numerical simulation of liquid-vapor phase transition phenomena. The study is divided into two part: first we investigate phase transition phenomena with a Van Der Waals equation of state (non monotonic equation of state), then we adopt an alternative approach with two equations of state. In the first part, we study the classical viscous criteria for selecting weak solutions of the system used when the equation of state is non monotonic. Those criteria do not select physical solutions and therefore we focus a more recent criterion: the visco-capillary criterion. We use this criterion to exactly solve the Riemann problem (which imposes solving an algebraic scalar non linear equation). Unfortunately, this step is quite costly in term of CPU which prevent from using this method as a ground for building Godunov solvers. That is why we propose an alternative approach two equations of state. Using the least action principle, we propose a phase changing two-phase flow model which is based on the second thermodynamic principle. We shall then describe two equilibrium submodels issued from the relaxations processes when instantaneous equilibrium is assumed. Despite the weak hyperbolicity of the last sub-model, we propose stable numerical schemes based on a two-step strategy involving a convective step followed by a relaxation step. We show the ability of the system to simulate vapor bubbles nucleation. (author)

  11. Optimization of pulsed current GTAW process parameters for sintered hot forged AISI 4135 P/M steel welds by simulated annealing and genetic algorithm

    International Nuclear Information System (INIS)

    Joseph, Joby; Muthukumaran, S.

    2016-01-01

    Abundant improvements have occurred in materials handling, especially in metal joining. Pulsed current gas tungsten arc welding (PCGTAW) is one of the consequential fusion techniques. In this work, PCGTAW of AISI 4135 steel engendered through powder metallurgy (P/M) has been executed, and the process parameters have been highlighted applying Taguchi's L9 orthogonal array. The results show that the peak current (Ip), gas flow rate (GFR), welding speed (WS) and base current (Ib) are the critical constraints in strong determinant of the Tensile strength (TS) as well as percentage of elongation (% Elong) of the joint. The practical impact of applying Genetic algorithm (GA) and Simulated annealing (SA) to PCGTAW process has been authenticated by means of calculating the deviation between predicted and experimental welding process parameters

  12. Optimization of pulsed current GTAW process parameters for sintered hot forged AISI 4135 P/M steel welds by simulated annealing and genetic algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Joby; Muthukumaran, S. [National Institute of Technology, Tamil Nadu (India)

    2016-01-15

    Abundant improvements have occurred in materials handling, especially in metal joining. Pulsed current gas tungsten arc welding (PCGTAW) is one of the consequential fusion techniques. In this work, PCGTAW of AISI 4135 steel engendered through powder metallurgy (P/M) has been executed, and the process parameters have been highlighted applying Taguchi's L9 orthogonal array. The results show that the peak current (Ip), gas flow rate (GFR), welding speed (WS) and base current (Ib) are the critical constraints in strong determinant of the Tensile strength (TS) as well as percentage of elongation (% Elong) of the joint. The practical impact of applying Genetic algorithm (GA) and Simulated annealing (SA) to PCGTAW process has been authenticated by means of calculating the deviation between predicted and experimental welding process parameters.

  13. Design of the accelerator stand with the ecr-source for simulation experiments on the of radiation damage of the steels of the nuclear industry

    International Nuclear Information System (INIS)

    Chalykh, B.B.; Kuybeda, R.P.; Kulevoy, T.V.; Ziyatdinova, A.V.

    2014-01-01

    The imitation experiments of irradiation resistivity for steels used in nuclear industry by heavy ion beams are promising demand for material properties investigation. The formation of the defects on the real-existing reactors is fraught with many difficulties such as a long-term session of exposure and induced radioactivity in samples. Simulation of radiation defects on accelerators of charged particles does not have such a drawback. To form radiation defects in matter, it is necessary to have beams of various ions with different energy. The concept of the test bench based on a ECR heavy-ion source for the imitation experiments of the materials resistance under irradiation is presented and discussed.

  14. 20,000-hour stress-corrosion cracking tests on ASTM A36 and A387-9 steels in simulated Hanford groundwater

    International Nuclear Information System (INIS)

    James, L.A.

    1986-03-01

    Modified WOL specimens were employed to evaluate the susceptibility of two candidate container materials, A36 and A387-9 steels, to SCC in simulated groundwater at 250 0 C. The test duration was 20,000 hours. Post-test measurements of specimen compliance were not possible because significant build-up of corrosion products and/or mineral deposits on the fracture faces prevented a linear relationship between load and displacement. Considerable load was ''lost'' due to time-independent plasticity, time-dependent deformation and crack-face wedging, but the amounts lost were comparable to similar short-term tests conducted earlier. A number of direct and indirect observations suggested that no crack extension occurred during the environmental exposure. One indirect observation, the initial pre-test compliance measurements, suggested a possibility of crack extension occurred, but it is believed that these measurements were in error because of the experimental test set-up used in the program

  15. Experimental study and simulation of transformation induced plasticity, and multiphase behaviour of the 16MND5 vessel steel under aniso-thermal multiaxial loading

    International Nuclear Information System (INIS)

    Coret, M.

    2001-01-01

    This work deals with the aniso-thermal multiphase behaviour of the French vessel steel and more specially about the transformation plasticity in the cases of multiaxial non-proportional loadings paths. The first part of this report is devoted to the presentation of a high temperature tension-torsion experimental device enable of obtaining a large range of cooling rate. This experimental set-up is used to explore the transformation plasticity under proportional or non-proportional loading paths, during austenitic, bainitic and martensitic transformations. The results of the tests are compared to the Leblond's model. In the last part, we propose a two-scale behaviour model in which the type of each phase behaviour can be different. This meso-model is finally used to simulate two real tests on structures. (author) [fr

  16. Simulation of transient hydraulic behaviour of process engineering plant with long pipes. Simulation des instationaeren hydraulischen Verhaltens verfahrenstechnischer Anlagen mit langen Rohrleitungen

    Energy Technology Data Exchange (ETDEWEB)

    Raschke, E. (BASF AG, Ludwigshafen am Rhein (Germany)); Seelinger, P. (BASF AG, Ludwigshafen am Rhein (Germany)); Sperber, A. (BASF AG, Ludwigshafen am Rhein (Germany)); Strassburger, R. (BASF AG, Ludwigshafen am Rhein (Germany))

    1994-05-01

    A knowledge of transient flow processes is becoming increasingly important for the reliable design and control of process engineering plant. Transient flow processes occur, of example, in long liquid-carrying pipes: on start-up and shut-down of plant, in emergency shut-downs and fast closure, i.e. when liquid is rapidly decelerated or accelerated. The consequence of such an event is a hammer effect, i.e. a short, often violent change of pressure placing considerable stress on structures. Such hammer effects are readily calculated by numerical methods in single phase media. Technical devices for prevention of inadmissibly high pressure surges can also be designed by means of simulation calculations. However, hammer effects also occur by sudden condensation of vapours. A number of systems in which condensation hammer effects can occur are considered at the end of this contribution. Two special damping measures are presented. (orig.)

  17. Suppression of the initial transient in Monte Carlo criticality simulations; Suppression du regime transitoire initial des simulations Monte-Carlo de criticite

    Energy Technology Data Exchange (ETDEWEB)

    Richet, Y

    2006-12-15

    Criticality Monte Carlo calculations aim at estimating the effective multiplication factor (k-effective) for a fissile system through iterations simulating neutrons propagation (making a Markov chain). Arbitrary initialization of the neutron population can deeply bias the k-effective estimation, defined as the mean of the k-effective computed at each iteration. A simplified model of this cycle k-effective sequence is built, based on characteristics of industrial criticality Monte Carlo calculations. Statistical tests, inspired by Brownian bridge properties, are designed to discriminate stationarity of the cycle k-effective sequence. The initial detected transient is, then, suppressed in order to improve the estimation of the system k-effective. The different versions of this methodology are detailed and compared, firstly on a plan of numerical tests fitted on criticality Monte Carlo calculations, and, secondly on real criticality calculations. Eventually, the best methodologies observed in these tests are selected and allow to improve industrial Monte Carlo criticality calculations. (author)

  18. Large scale simulation numerical study of transition to turbulence in jets; Etude numerique par simulation des grandes echelles de la transition a la turbulence dans les jets

    Energy Technology Data Exchange (ETDEWEB)

    Urbin, Gerald [Institut National Polytechnique, 38 - Grenoble (France)

    1998-02-02

    This study highlights the potentialities of the numerical technique of large scale simulation in describing and understanding the turbulent flows in a complex geometry. Particularly, it is focussed on flows of free jet, confined jets and multiple jets of high solidity grid. Spatial simulations of the circular zone close to a free jet, of high Reynolds number were performed. In spite of an evident sensitivity to upstream conditions good agreement between our statistical predictions and different experimental measurements was obtained. The multiple coherent vortical structures implied in the transition to turbulence of the jet were found. At the same time, helical or annular axisymmetric vortices were observed. Also, an original vortical arrangement was evidenced, resulting from the alternating inclination and local pairing of these rings. It could been forced through an ad-hoc excitation which modifies subsequently drastically the jet development. When an axisymmetric excitation is imposed after formation of annular structures, pairs of counter-rotative longitudinal vortices occur and generate lateral jets. Their nature and presence in case of a helical excitation are discussed. An efficient method for controlling their number is developed. Then, one is studied the very low frequency periodic phenomenon of backward-facing transition to turbulence which develops in the confined jet and grid multiple jets (a phenomenon generic in numerous flows). It was found to depend not only on the characteristic of the re-circulation (pre-transition) zones but also on the upstream flow (zone of post-transition stagnation, pressure effect). Large scale transversal motions of the fluid have been found beginning from the grid. An interpretation of this phenomenon is suggested 193 refs., 109 figs.

  19. Aqueous corrosion of borosilicate glasses: experiments, modeling and Monte-Carlo simulations; Alteration par l'eau des verres borosilicates: experiences, modelisation et simulations Monte-Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Ledieu, A

    2004-10-01

    This work is concerned with the corrosion of borosilicate glasses with variable oxide contents. The originality of this study is the complementary use of experiments and numerical simulations. This study is expected to contribute to a better understanding of the corrosion of nuclear waste confinement glasses. First, the corrosion of glasses containing only silicon, boron and sodium oxides has been studied. The kinetics of leaching show that the rate of leaching and the final degree of corrosion sharply depend on the boron content through a percolation mechanism. For some glass contents and some conditions of leaching, the layer which appears at the glass surface stops the release of soluble species (boron and sodium). This altered layer (also called the gel layer) has been characterized with nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. Second, additional elements have been included in the glass composition. It appears that calcium, zirconium or aluminum oxides strongly modify the final degree of corrosion so that the percolation properties of the boron sub-network is no more a sufficient explanation to account for the behavior of these glasses. Meanwhile, we have developed a theoretical model, based on the dissolution and the reprecipitation of the silicon. Kinetic Monte Carlo simulations have been used in order to test several concepts such as the boron percolation, the local reactivity of weakly soluble elements and the restructuring of the gel layer. This model has been fully validated by comparison with the results on the three oxide glasses. Then, it has been used as a comprehensive tool to investigate the paradoxical behavior of the aluminum and zirconium glasses: although these elements slow down the corrosion kinetics, they lead to a deeper final degree of corrosion. The main contribution of this work is that the final degree of corrosion of borosilicate glasses results from the competition of two opposite mechanisms

  20. Water leaching of borosilicate glasses: experiments, modeling and Monte Carlo simulations; Alteration par l'eau des verres borosilicates: experiences, modelisation et simulations Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Ledieu, A

    2004-10-15

    This work is concerned with the corrosion of borosilicate glasses with variable oxide contents. The originality of this study is the complementary use of experiments and numerical simulations. This study is expected to contribute to a better understanding of the corrosion of nuclear waste confinement glasses. First, the corrosion of glasses containing only silicon, boron and sodium oxides has been studied. The kinetics of leaching show that the rate of leaching and the final degree of corrosion sharply depend on the boron content through a percolation mechanism. For some glass contents and some conditions of leaching, the layer which appears at the glass surface stops the release of soluble species (boron and sodium). This altered layer (also called the gel layer) has been characterized with nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. Second, additional elements have been included in the glass composition. It appears that calcium, zirconium or aluminum oxides strongly modify the final degree of corrosion so that the percolation properties of the boron sub-network is no more a sufficient explanation to account for the behavior of these glasses. Meanwhile, we have developed a theoretical model, based on the dissolution and the reprecipitation of the silicon. Kinetic Monte Carlo simulations have been used in order to test several concepts such as the boron percolation, the local reactivity of weakly soluble elements and the restructuring of the gel layer. This model has been fully validated by comparison with the results on the three oxide glasses. Then, it has been used as a comprehensive tool to investigate the paradoxical behavior of the aluminum and zirconium glasses: although these elements slow down the corrosion kinetics, they lead to a deeper final degree of corrosion. The main contribution of this work is that the final degree of corrosion of borosilicate glasses results from the competition of two opposite mechanisms

  1. Water leaching of borosilicate glasses: experiments, modeling and Monte Carlo simulations; Alteration par l'eau des verres borosilicates: experiences, modelisation et simulations Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Ledieu, A

    2004-10-15

    This work is concerned with the corrosion of borosilicate glasses with variable oxide contents. The originality of this study is the complementary use of experiments and numerical simulations. This study is expected to contribute to a better understanding of the corrosion of nuclear waste confinement glasses. First, the corrosion of glasses containing only silicon, boron and sodium oxides has been studied. The kinetics of leaching show that the rate of leaching and the final degree of corrosion sharply depend on the boron content through a percolation mechanism. For some glass contents and some conditions of leaching, the layer which appears at the glass surface stops the release of soluble species (boron and sodium). This altered layer (also called the gel layer) has been characterized with nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. Second, additional elements have been included in the glass composition. It appears that calcium, zirconium or aluminum oxides strongly modify the final degree of corrosion so that the percolation properties of the boron sub-network is no more a sufficient explanation to account for the behavior of these glasses. Meanwhile, we have developed a theoretical model, based on the dissolution and the reprecipitation of the silicon. Kinetic Monte Carlo simulations have been used in order to test several concepts such as the boron percolation, the local reactivity of weakly soluble elements and the restructuring of the gel layer. This model has been fully validated by comparison with the results on the three oxide glasses. Then, it has been used as a comprehensive tool to investigate the paradoxical behavior of the aluminum and zirconium glasses: although these elements slow down the corrosion kinetics, they lead to a deeper final degree of corrosion. The main contribution of this work is that the final degree of corrosion of borosilicate glasses results from the competition of two opposite mechanisms

  2. Aqueous corrosion of borosilicate glasses: experiments, modeling and Monte-Carlo simulations; Alteration par l'eau des verres borosilicates: experiences, modelisation et simulations Monte-Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Ledieu, A

    2004-10-01

    This work is concerned with the corrosion of borosilicate glasses with variable oxide contents. The originality of this study is the complementary use of experiments and numerical simulations. This study is expected to contribute to a better understanding of the corrosion of nuclear waste confinement glasses. First, the corrosion of glasses containing only silicon, boron and sodium oxides has been studied. The kinetics of leaching show that the rate of leaching and the final degree of corrosion sharply depend on the boron content through a percolation mechanism. For some glass contents and some conditions of leaching, the layer which appears at the glass surface stops the release of soluble species (boron and sodium). This altered layer (also called the gel layer) has been characterized with nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. Second, additional elements have been included in the glass composition. It appears that calcium, zirconium or aluminum oxides strongly modify the final degree of corrosion so that the percolation properties of the boron sub-network is no more a sufficient explanation to account for the behavior of these glasses. Meanwhile, we have developed a theoretical model, based on the dissolution and the reprecipitation of the silicon. Kinetic Monte Carlo simulations have been used in order to test several concepts such as the boron percolation, the local reactivity of weakly soluble elements and the restructuring of the gel layer. This model has been fully validated by comparison with the results on the three oxide glasses. Then, it has been used as a comprehensive tool to investigate the paradoxical behavior of the aluminum and zirconium glasses: although these elements slow down the corrosion kinetics, they lead to a deeper final degree of corrosion. The main contribution of this work is that the final degree of corrosion of borosilicate glasses results from the competition of two opposite mechanisms

  3. Molecular Simulations As a Tool for Predicting Phase Equilibria and Transport Properties of Fluids Les simulations moléculaires comme outils pour prédire les équilibres de phases et les propriétés de transport des fluides

    Directory of Open Access Journals (Sweden)

    Fuchs A.

    2006-12-01

    Full Text Available koWe briefly review the molecular simulation methods which can be used to predict thermophysical properties of fluids and fluid mixtures. It is shown in this paper, on the one hand, how the Gibbs Ensemble Monte Carlo Method allows phase behavior predictions for real fluids under conditions for which experimental data are difficult or impossible to obtain. On the other hand, the molecular dynamics methods used for predicting transport properties of molecular fluids are described. Finally we discuss possible future applications of these methods. Dans cet article, nous passons brièvement en revue les méthodes de simulation moléculaire applicables à la prédiction des propriétés thermophysiques des fluides et des mélanges. Nous montrons, d'une part, comment la méthode de Monte-Carlo dans l'ensemble de Gibbs permet de prédire le comportement de phase de fluides réels dans des conditions telles que l'acquisition de données expérimentales serait difficile, voire impossible. D'autre part, nous décrivons les méthodes de dynamique moléculaire utilisées pour prédire les propriétés de transport de fluides moléculaires. Enfin, nous discutons le potentiel de ces méthodes pour les applications futures.

  4. High temperature cracking of steels: effect of geometry on creep crack growth laws

    International Nuclear Information System (INIS)

    Kabiri, M.R.

    2003-12-01

    This study was performed at Centre des Materiaux de l'Ecole des Mines de Paris. It deals with identification and transferability of high temperature creep cracking laws of steels. A global approach, based on C * and J non-linear fracture mechanics parameters has been used to characterize creep crack initiation and propagation. The studied materials are: the ferritic steels 1Cr-1Mo-1/4V (hot and cold parts working at 540 and 250 C) used in the thermal power stations and the austenitic stainless steel 316 L(N) used in the nuclear power stations. During this thesis a data base was setting up, it regroups several tests of fatigue, creep, creep-fatigue, and relaxation. Its particularity is to contain several creep tests (27 tests), achieved at various temperatures (550 to 650 C) and using three different geometries. The relevance of the C * parameter to describe the creep crack propagation was analysed by a means of systematic study of elasto-viscoplastic stress singularities under several conditions (different stress triaxiality). It has been shown that, besides the C * parameter, a second non singular term, denoted here as Q * , is necessary to describe the local variables in the vicinity of the crack tip. Values of this constraint parameter are always negative. Consequently, application of typical creep crack growth laws linking the creep crack growth rate to the C * parameter (da/dt - C * ), will be conservative for industrial applications. Furthermore, we showed that for ferritic steels, crack incubation period is important, therefore a correlation of Ti - C * type has been kept to predict crack initiation time Ti. For the austenitic stainless steel, the relevant stage is the one of the crack propagation, so that a master curve (da/dt - C * ), using a new data analysis method, was established. Finally, the propagation of cracks has been simulated numerically using the node release technique, allowing to validate analytical expressions utilised for the experimental

  5. Photovoltaics for appliances and small systems. Enhancement of the PVS for Windows simulation program for development and simulation of PV appliances and small systems. Final report; Photovoltaik fuer Geraete und Kleinsysteme. Erweiterung des Simulationsprogramms PVS fuer Windows zur Entwicklung und Simulation von PV-versorgten Geraeten und Kleinsystemen. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, R.; Imann, C.; Jung, V.

    2002-06-28

    The PVS simulation program for Windows was to be extended to the development and simulation of PV-supported equipment and small systems. The following new functions were to be integrated: a) Simulation and dimensioning of indoor power supply of systems with different light sources and independent outdoor systems. b)Integration of small wind generators in the simulation and dimensioning of isolated autonomous systems, including wind data and a component database for small wind turbines; c) Differentiation of the PVS battery model for different battery types (lead, Ni/Cd, Li etc.), optimized operating strategies and flexible dimensioning including an additional component database for battery types; d) Extensive cost analysis for PV-supported appliances and small systems, from investments to consumption, operation and maintenance. This will facilitate investment decisions and help systems of this type along in the market. All program components were designed for high flexibility. Users should be able to vary as many parameters as possible, and to generate and modify their own records. The current project focused on the user interface, i.e. input, data processing, and output. Parallel to this, the Fraunhofer ISE Institute worked on modifications of the computer hardware. [German] Das Projekt zielte auf eine Erweiterung des Simulationsprogramms PVS fuer Windows zur Entwicklung und Simulation von PV-versorgten Geraeten und Kleinsystemen hin. Das Entwicklungsprodukt sollte zusaetzlich zu den bisherigen Funktionen insbesondere Folgendes leisten: (a) Simulation und Dimensionierung der Energieversorgung von Geraeten im Indoor-Bereich, wobei unterschiedliche Lichtquellen verarbeitet werden muessen, sowie von sonstigen netzfreien (Outdoor-) Kleinsystemen. (b) Einbindung kleiner Windgeneratoren in die Simulation und Dimensionierung von netzfernen Systemen (Insel-Anlagen), einschliesslich Bereitstellung der Wind-Daten und einer zusaetzlichen Komponenten-Datenbank fuer kleine

  6. Investigation on the corrosion resistance of PIM 316L stainless steel in PEM fuel cell simulated environment

    International Nuclear Information System (INIS)

    Oliveira, Mara Cristina Lopes de; Costa, Isolda; Antunes, Renato Altobelli

    2009-01-01

    Bipolar plates play main functions in PEM fuel cells, accounting for the most part of the weight and cost of these devices. Powder metallurgy may be an interesting manufacturing process of these components owing to the production of large scale, complex near-net shape parts. However, corrosion processes are a major concern due to the increase of the passive film thickness on the metal surface, lowering the power output of the fuel cell. In this work, the corrosion resistance of PIM AISI 316L stainless steel specimens was evaluated in 1M H 2 SO 4 + 2 ppm HF solution at room temperature during 30 days of immersion. The electrochemical measurements comprised potentiodynamic polarization and electrochemical impedance spectroscopy. The surface morphology of the specimens was observed before and after the corrosion tests through SEM images. The material presented low corrosion current density suggesting that it is suitable to operate in the PEM fuel cell environment. (author)

  7. Construction and simulation of the KAOS spectrometer for coincidence measurements in the associated kaon production; Aufbau und Simulation des KAOS-Spektrometers fuer Koinzidenzmessungen in der assoziierten Kaonproduktion

    Energy Technology Data Exchange (ETDEWEB)

    Nungesser, Lars

    2009-05-27

    With the extension of the Mainz microtron MAMI at the Institut fuer Kernphysik with a third stage it is now possible to produce particles with open strangeness. For their detection the spectrometer facility of the A1 collaboration has been expanded with the KAOS-spectrometer which has been inherited from GSI in Darmstadt. We are studying the p(e,e'K{sup +}){lambda}/Sigma{sup 0} reaction where the outgoing electron and kaon have to be detected. If we use a different target than hydrogen there is the possibility of a hypernuceus being formed. Spectroscopy of these gives the opportunity to study the hyperon potential within the atomic nucleus and the hyperon-nucleon interaction. Due to the good quality of the electron beam mass resolutions of a few hundred keV/c{sup 2} can be achieved. The detectors and the optical properties of the spectrometer have been simulated with GEANT4. Hit pattern in the detectors have been generated to aid the programming of the FPGA-based trigger. A first mapping of the detector coordinates to the target coordinates has been generated. For the experiments with hypernuclei KAOS has to be placed at 0 forward angle and the primary electron beam has to go via a magnetic chicane through the dipole. The simulation shows only a slight increase of the radiation for this case, especially around the beam-dump. Thus it is possible to operate KAOS as double sided spectrometer at MAMI. Within the scope of this thesis the readout and control electronics for all detectors had to be integrated into the existing A1 data acquisition and into the control system. During two beamtimes in autumn 2008 kaons where detected in the angular range between 20 and 40 and the momentum range between 400 MeV/c and 600 MeV/c. A time resolution of 1ns FWHM could be achieved which allows particle identification. The angular and momentum resolution was sufficient to identify {lambda} and {sigma}{sup 0} hyperons in the missing mass spectrum. (orig.)

  8. Numerical simulations for the area of the German Bight in spring 1995; Numerische Simulationsrechnungen fuer das Gebiet der Deutschen Bucht am Beispiel des Fruehjahrs 1995

    Energy Technology Data Exchange (ETDEWEB)

    Lenz, C.J. [Hamburg Univ. (Germany). Meteorologisches Inst.

    1998-01-01

    The paper reports results of the mesoscale transport, chemism and flow model METRAS for the period from 22 April to 11 May 1995. During this period, a measurement campaign was carried out in the area of the German Bight under the ``KUSTOS`` springtime scheme (``Coastal mass and energy transport processes - The transition from land to sea in the south-eastern North Sea``). In order to take instationary and inhomogeneous weather situations into account, the modellings used data provided by the German weather service, which form part of its Germany model (DM), both to initialize and drive the METRAS data. The modelling results of METRAS are compared with routine readings taken by the German weather service in some selected measuring sites. (orig./KW) [Deutsch] In diesem Beitrag werden Ergebnisse des mesoskaligen Transport-, Chemie- und Stroemungsmodells METRAS fuer den Zeitraum vom 22. April bis zum 11. Mai 1995 vorgestellt, in dem die Messkampagne des KUSTOS-Fruehjahrsexperimentes (Kuestennahe Stoff- und Energietransporte - der Uebergang Land - Meer in der suedoestlichen Nordsee) im Bereich der Deutschen Bucht stattfand. Zur Beruecksichtigung instationaerer und inhomogener Wetterlagen bei den Modellrechnungen wurden sowohl zur Initialisierung als auch zum Antrieb von METRAS Daten des Deutschland-Modells (DM) des Deutschen Wetterdienstes verwendet. Die Modellergebnisse von METRAS werden mit Routinemessungen des Deutschen Wetterdienstes an einigen ausgewaehlten Messstationen verglichen. (orig./KW)

  9. Study of the Pierre Auger Observatory ground detectors: tests, simulation and calibration; Etude des detecteurs de surface de l'observatoire Pierre Auger: tests, simulation et etalonnage

    Energy Technology Data Exchange (ETDEWEB)

    Creusot, A

    2004-10-01

    The Pierre Auger Observatory is intended to the ultra high energy cosmic rays study. This study is realized through the particles showers coming from the interaction between the cosmic rays and the atmosphere. The ground detection of these showers requires a comprehensive understanding of the detectors. Several test tanks have been elaborated for this purpose, especially the Orsay one. The first chapter is dedicated to the presentation of the cosmic rays and of the Pierre Auger Observatory. The second one describes the detectors used for the Observatory surface array. The Orsay test tank is then presented and detailed. We study the results we have got with the Orsay test tank in the fourth chapter and compare these results with those of the Observatory detectors in the fifth chapter. The sixth chapter is dedicated to the validation of the results set through the simulation (GEANT4 software). Finally, the first detected particles showers are presented in the seventh chapter. The data acquisition has begun this year. The construction will be finished by end of 2005. From this moment, The Pierre Auger Observatory will allow us to contribute to solving the cosmic rays puzzle. (author)

  10. Processing of reservoir data for diagenesis simulation; Traitement des donnees de reservoir en vue d`une simulation de la diagenese

    Energy Technology Data Exchange (ETDEWEB)

    Pelletier, I.

    1997-12-18

    Diagenetic minerals frequently damage reservoir permeability. A numerical model which couples chemical reactions and transport of dissolved elements can help to predict both location and magnitude of cementations. The present Ph.D. examines how can be applied such a modelling approach to a complex heterogeneous reservoir. Petrographical data from core samples are used as input data, or alternatively as controls for validating the modelling results. The measurements, acquired with dm-to-m spacing are too numerous to be integrated in a reactions-transport code. The usual up-scaling methods, called Homogenization, conserve only the fluid flow properties. A new method, called `Gathering` takes into account material transport balance. It is proposed in the first part of the dissertation. In the second part, an application of Gathering is done simulating illitization in the sub-arkosic sandstones of the Ness formation (Brent Group) in a North Sea field, Dunbar.. As a prerequisite, data accuracy is examined for a set of `routine measurements` (100 points counting on thin section, XR-diffractometry and gas porosity/permeability). (author) 60 refs.

  11. Deformable object model and simulation. Application to lung cancer treatment; Modelisation et simulation parametrable d'objets deformables. Application aux traitements des cancers pulmonaires

    Energy Technology Data Exchange (ETDEWEB)

    Baudet, V

    2006-06-15

    Ionising treatment against cancers such as conformal radiotherapy and hadron therapy are set with error margins that take into account statistics of tumour motions, for instance. We are looking for reducing these margins by searching deformable models that would simulate displacements occurring in lungs during a treatment. It must be personalized with the geometry obtained from CT scans of the patient and also it must be parameterized with physiological measures of the patient. In this Ph. D. thesis, we decided to use a mass-spring system to model lungs because of its fast and physically realist deformations obtained in animation. As a starting point, we chose the model proposed by Van Gelder in order to parameterize a mass-spring system with rheological characteristics of an homogeneous, linear elastic isotropic material in two dimensions (2D). However, we tested this model and proved it was false. Hence we did a Lagrangian study in order to obtain a parametric model with rectangular in 2D (cubic in 3D) elements. We also determined the robustness by testing with stretching, inflating, shearing and bending experiments and also by comparing results with other infinite element method. Thus, in this Ph.D. thesis, we explain how to obtain this parametric model, and how it will be linked to physiological data and how accurate it will be. (author)

  12. Study of the Pierre Auger Observatory ground detectors: tests, simulation and calibration; Etude des detecteurs de surface de l'observatoire Pierre Auger: tests, simulation et etalonnage

    Energy Technology Data Exchange (ETDEWEB)

    Creusot, A

    2004-10-01

    The Pierre Auger Observatory is intended to the ultra high energy cosmic rays study. This study is realized through the particles showers coming from the interaction between the cosmic rays and the atmosphere. The ground detection of these showers requires a comprehensive understanding of the detectors. Several test tanks have been elaborated for this purpose, especially the Orsay one. The first chapter is dedicated to the presentation of the cosmic rays and of the Pierre Auger Observatory. The second one describes the detectors used for the Observatory surface array. The Orsay test tank is then presented and detailed. We study the results we have got with the Orsay test tank in the fourth chapter and compare these results with those of the Observatory detectors in the fifth chapter. The sixth chapter is dedicated to the validation of the results set through the simulation (GEANT4 software). Finally, the first detected particles showers are presented in the seventh chapter. The data acquisition has begun this year. The construction will be finished by end of 2005. From this moment, The Pierre Auger Observatory will allow us to contribute to solving the cosmic rays puzzle. (author)

  13. Large Eddy simulations of flame/acoustics interactions in a swirl flow; Simulation aux grandes echelles des interactions flamme / acoustique dans un ecoulement vrille

    Energy Technology Data Exchange (ETDEWEB)

    Selle, L.

    2004-01-15

    Swirl flows exhibit a large variety of topologies, depending on the ratio of the flux axial momentum to the axial flux of tangential momentum: this ratio is called swirl number. Above a given critical value for the swirl number, the pressure gradient reverses the flow on the axis of rotation. This central recirculation zone is used in turbines for flame stabilization. And yet, reacting-swirled flows can exhibit combustion instabilities resulting from the coupling between acoustics and unsteady heat release. Combustion instabilities can lead to loss of control or even complete destruction of the system. Their prediction is impossible with standard engineering tools. The work presented here investigates the capabilities of numerical research tools for the prediction of combustion instabilities. Large-Eddy Simulation (LES) is implemented in a code solving the Navier-Stokes equations for compressible-multi-components fluids (code AVBP developed at CERFACS). This method takes into account for the major ingredients of combustion instabilities such as acoustics and flame / vortex interaction. The LES methodology is validated in the swirled flow from a complex industrial burner (SIEMENS PG). Both reactive and non-reactive regimes are successfully compared with experimental data in terms of mean temperature and mean and RMS velocities. Experimental measurements were performed at the university of Karlsruhe (Germany). A detailed analysis of the acoustics and its interaction with the flame front is performed with the code AVSP, also developed at CERFACS. (author)

  14. Probabilistic methods for the simulation of fuel particles behavior under irradiation; Apport des methodes probabilistes dans la simulation du comportement sous irradiation du combustible a particules

    Energy Technology Data Exchange (ETDEWEB)

    Cannamela, C

    2007-09-15

    This work is devoted to the evaluation of mathematical expectations in the context of structural reliability. We seek a failure probability estimate (that we assume low), taking into account the uncertainty of influential parameters of the System. Our goal is to reach a good compromise between the accuracy of the estimate and the associated computational cost. This approach is used to estimate the failure probability of fuel particles from a HTR-type nuclear reactor. This estimate is obtain by means of costly numerical simulations. We consider different probabilistic methods to tackle the problem. First, we consider a variance reducing Monte Carlo method: importance sampling. For the parametric case, we propose adaptive algorithms in order to build a series of probability densities that will eventually converge to optimal importance density. We then present several estimates of the mathematical expectation based on this series of densities. Next, we consider a multi-level method using Monte Carlo Markov Chain algorithm. Finally, we turn our attention to the related problem of quantile estimation (non extreme) of physical output from a large-scale numerical code. We propose a controlled stratification method. The random input parameters are sampled in specific regions obtained from surrogate of the response. The estimation of the quantile is then computed from this sample. (author)

  15. ANALYSE DES PERCEPTIONS LOCALES ET DES FACTEURS ...

    African Journals Online (AJOL)

    AISA

    1Faculté des Sciences Agronomiques (FSA), Université d'Abomey-Calavi (UAC), 01 BP 526 Cotonou Bénin. Email : cgbemavo@yahoo.fr. 2Institut National des Recherches Agricoles du Bénin, Centre de Recherches Agricoles d'Agonkanmey (CRA-A),. Laboratoire des Sciences du Sol, Eau et Environnement (LSSEE).

  16. Simulation de l'habitat physique du barbeau fluviatile (Barbus barbus, L. 1758 : choix des modèles biologiques et sensibilité de la réponse

    Directory of Open Access Journals (Sweden)

    POUILLY M.

    1994-07-01

    Full Text Available Des courbes monovariées et des modèles multivariés de préférence d'habitat du barbeau, Barbus barbus, ont été établis à partir de données récoltées sur 3 cours d'eau. Dans les deux cas (monovarié et multivarié, trois modèles locaux, correspondant aux données d'une rivière, et un modèle général, regroupant l'ensemble des données, ont été établis. La qualité de la prédiction et la sensibilité de la réponse lors de la simulation des capacités d'accueil d'un cours d'eau révèlent : 1 que les modèles multivariés ont une valeur prédictive plus forte que les courbes de préférence, 2 que les modèles construits à partir de jeux de données locaux sont plus performants que les modèles généraux, et 3 que la perte de précision est moindre dans le cas du modèle général multivarié.

  17. Steel refining possibilities in LF

    Science.gov (United States)

    Dumitru, M. G.; Ioana, A.; Constantin, N.; Ciobanu, F.; Pollifroni, M.

    2018-01-01

    This article presents the main possibilities for steel refining in Ladle Furnace (LF). These, are presented: steelmaking stages, steel refining through argon bottom stirring, online control of the bottom stirring, bottom stirring diagram during LF treatment of a heat, porous plug influence over the argon stirring, bottom stirring porous plug, analysis of porous plugs disposal on ladle bottom surface, bottom stirring simulation with ANSYS, bottom stirring simulation with Autodesk CFD.

  18. Improved Mask Protected DES using RSA Algorithm

    Directory of Open Access Journals (Sweden)

    Asha Latha S.

    2016-01-01

    Full Text Available The data encryption standard is a pioneering and farsighted standard which helped to set a new paradigm for encryption standards. But now DES is considered to be insecure for some application. Asymmetric mask protected DES is an advanced encryption method for effectively protecting the advanced DES. There are still probabilities to improve its security. This paper propose a method, which introduce a RSA key generation scheme in mask protected DES instead of plain key, which result in enhancement in the security of present asymmetric mask protected DES. We further propose a Vedic mathematical method of RSA implementation which reduce the complexity of computation in RSA block thereby resulting in reduced delay (four timesthat improves the performance of overall system. The software implementation was performed using Xilinx 13.2 and Model-Sim was used for the simulation environment.

  19. Correlation Between Microstructure and Low-Temperature Impact Toughness of Simulated Reheated Zones in the Multi-pass Weld Metal of High-Strength Steel

    Science.gov (United States)

    Kang, Yongjoon; Park, Gitae; Jeong, Seonghoon; Lee, Changhee

    2018-01-01

    A large fraction of reheated weld metal is formed during multi-pass welding, which significantly affects the mechanical properties (especially toughness) of welded structures. In this study, the low-temperature toughness of the simulated reheated zone in multi-pass weld metal was evaluated and compared to that of the as-deposited zone using microstructural analyses. Two kinds of high-strength steel welds with different hardenabilities were produced by single-pass, bead-in-groove welding, and both welds were thermally cycled to peak temperatures above Ac3 using a Gleeble simulator. When the weld metals were reheated, their toughness deteriorated in response to the increase in the fraction of detrimental microstructural components, i.e., grain boundary ferrite and coalesced bainite in the weld metals with low and high hardenabilities, respectively. In addition, toughness deterioration occurred in conjunction with an increase in the effective grain size, which was attributed to the decrease in nucleation probability of acicular ferrite; the main cause for this decrease changed depending on the hardenability of the weld metal.

  20. Tables of formulae for calculating the mechanics of stacks in gas-graphite reactors; Formulaire pour le calcul de la mecanique des empilements des reacteurs graphite-gaz

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1968-07-01

    This collection of formulae only gives, for nuclear graphite stacks. The mechanical effects due to the strains, thermal or not, of steel structures supporting or surrounding graphite blocks. Equations have been established by mean of experiments made at Chinon with large pile models. Thus, it is possible to calculate displacement, strain and stress in the EDF type stacks of horizontal triangular block lattice. (authors) [French] Le domaine de ce formulaire est strictement limite aux effets mecaniques, pour les empilements, des deformations, thermiques ou autres, des structures metalliques de soutien (aire - support et corset). On propose un ensemble de relations qui ont ete etablies a la suite des essais de CHINON sur des maquettes de grande taille. Ces relations permettent le calcul des mouvements, des deformations et des contraintes dans les empilements du type EDF, a reseau horizontal triangulaire regulier. (auteurs)

  1. Effects of cold working ratio and stress intensity factor on intergranular stress corrosion cracking susceptibility of non-sensitized austenitic stainless steels in simulated BWR and PWR primary water

    International Nuclear Information System (INIS)

    Yaguchi, Seiji; Yonezawa, Toshio

    2012-01-01

    To evaluate the effects of cold working ratio, stress intensity factor and water chemistry on an IGSCC susceptibility of non-sensitized austenitic stainless steel, constant displacement DCB specimens were applied to SCC tests in simulated BWR and PWR primary water for the three types of austenitic stainless steels, Types 316L, 347 and 321. IGSCC was observed on the test specimens in simulated BWR and PWR primary water. The observed IGSCC was categorized into the following two types. The one is that the IGSCC observed on the same plane of the pre-fatigue crack plane, and the other is that the IGSCC observed on a plane perpendicular to the pre-fatigue crack plane. The later IGSCC fractured plane is parallel to the rolling plane of a cold rolled material. Two types of IGSCC fractured planes were changed according to the combination of the testing conditions (cold working ratio, stress intensity factor and simulated water). It seems to suggest that the most susceptible plane due to fabrication process of materials might play a significant role of IGSCC for non-sensitized cold worked austenitic stainless steels, especially, in simulated PWR primary water. Based upon evaluating on the reference crack growth rate (R-CGR) of the test specimens, the R-CGR seems to be mainly affected by cold working ratio. In case of simulated PWR primary water, it seems that the effect of metallurgical aspects dominates IGSCC susceptibility. (author)

  2. Masonry arches retrofitted with steel reinforced grout materials: In-situ experimental tests and advanced FE simulations

    Science.gov (United States)

    Bertolesi, Elisa; Carozzi, Francesca Giulia; Milani, Gabriele; Poggi, Carlo

    2017-11-01

    The paper presents the results of a series of in-situ tests carried out on two masonry arches, one unreinforced and the other reinforced with SRG (Steel Reinforced Grout). The arches are built adopting a peculiar construction technique using common Italian bricks with dimensions 250 × 120 × 55 mm3 and 10 mm thick mortar joints. One of the two arches has been reinforced with an SRG material constituted by an inox grid embedded into a layer of lime mortar, whereas the second one is maintained unreinforced for comparison purposes. The experimental set-up is designed to apply an eccentric vertical load placed at ¼ of the span in a series of loading and unloading cycles up to the failure. The numerical analyses have been performed using a sophisticated heterogeneous micro-modeling technique, where bricks, mortar joints and the strengthening have been modeled separately. Finally, the numerical outcomes have been comparatively assessed with respect to the experimental results and the crack patterns obtained at the end of the tests, showing a satisfactory agreement in terms of the global behavior of the arches and their collapse mechanisms.

  3. Development of novel protective high temperature coatings on heat exchanger steels and their corrosion resistance in simulated coal firing environment; Developpement de revetements pour les aciers d'echangeurs thermiques et amelioration de leur resistance a la corrosion en environnement simulant les fumees de combustion et de charbon

    Energy Technology Data Exchange (ETDEWEB)

    Rohr, V.

    2005-10-15

    Improving the efficiencies of thermal power plants requires an increase of the operating temperatures and thus of the corrosion resistance of heat exchanger materials. Therefore, the present study aimed at developing protective coatings using the pack cementation process. Two types of heat exchanger steels were investigated: a 17% Cr-13% Ni austenitic steel and three ferritic-martensitic steels with 9 (P91 and P92) and 12% Cr (HCM12A). The austenitic steel was successfully aluminized at 950 C. For the ferritic-martensitic steels, the pack cementation temperature was decreased down to 650 C, in order to maintain their initial microstructure. Two types of aluminides, made of Fe{sub 2}Al{sub 5} and FeAl, were developed. A mechanism of the coating formation at low temperature is proposed. Furthermore, combining the pack cementation with the conventional heat treatment of P91 allowed to take benefit of higher temperatures for the deposition of a two-step Cr+Al coating. The corrosion resistance of coated and uncoated steels is compared in simulated coal firing environment for durations up to 2000 h between 650 and 700 C. It is shown that the coatings offer a significant corrosion protection and, thus, an increase of the component lifetime. Finally, the performance of coated 9-12% Cr steels is no longer limited by corrosion but by interdiffusion between the coating and the substrate. (author)

  4. La dimension sociale dans un master post-universitaire à distance : outils, animation et analyse des interactions The social dimension within an online post-graduate course: tools, simulation and interaction analysis

    Directory of Open Access Journals (Sweden)

    Simone Torsani

    2008-11-01

    Full Text Available Les technologies de l'information et de la communication (TIC dans la formation peuvent favoriser l'adoption de modèles éducatifs de type socioconstructiviste. Dans ces contextes de formation (computer-supported collaborative learning, CSCL, une attention particulière est consacrée à la création de la communauté d'apprentissage et aux relations qui s'instaurent entre ses membres. Le master de haute formation en traduction juridique de l'université de Gênes – projet F@rum (Poli et al., 2004, se base sur ces théories. Pour favoriser au maximum le développement de la présence sociale de la communauté d'apprentissage, un "jeu de simulation socio-professionnel" (Debyser, 1996 ; Rossi, 2002 a été organisé par l'équipe du master, à l'intérieur d'une plateforme dédiée. Dans cette étude, nous décrirons les initiatives destinées à encourager la présence sociale à l'intérieur du master. Nous chercherons à comprendre également si et dans quelle mesure ces initiatives ont influencé la présence sociale des participants ; si elles ont stimulé la création de la communauté d'apprentissage et si elles ont contribué à l'atteinte des objectifs cognitifs du master. Cette contribution se fonde en particulier sur les résultats de l'analyse des interactions des apprenants indiquant la présence sociale (Garrison et al., 1999. L'analyse des messages des forums repose sur un modèle d'évaluation dit "mixte" (quantitatif et qualitatif à cinq dimensions (Pozzi et al., 2007 inspiré des "communities of inquiry" (Garrison & Anderson, 2003.The use of ICTs in the field of education can promote the adoption of "social constructivist" approaches to learning. In these contexts of education (computer-supported collaborative learning, CSCL, a particular attention is paid to the creation of the "learning community" and to the relationships the members of the community establish among them. The post-graduate course in legal translation of

  5. Thermal Evolution of Crude Oils in Sedimentary Basins: Experimental Simulation in a Confined System and Kinetic Modeling Evolution thermique des huiles dans les bassins sédimentaires : simulation expérimentale par pyrolyse en milieu confiné et modélisation cinétique

    Directory of Open Access Journals (Sweden)

    Behar F.

    2006-11-01

    coefficients alphaij were optimized with reference to a dataset comprising the final compositions resulting from oil pyrolysis experiments. This optimization was carried out successively on each distillate and each residue, on both distillate and residue from the same oil, then on the two distillates and two residues altogether. The model accounts satisfactorily for the specific kinetics of cracking of both each oil and of the two oils together, suggesting that it is now possible to predict the thermal behavior of a given oil provided the proportions of the ten fractions selected for the model are known. The wide temperature range in which the model is valid, supports its extrapolation to the temperature range of sedimentary basins. Une meilleure connaissance des mécanismes du craquage thermique des huiles doit permettre de mieux comprendre leur évolution naturelle dans les bassins sédimentaires et donc d'améliorer les modèles actuels utilisés pour prédire la formation du gaz. Bien que les mécanismes de craquage soient bien connus pour des composés modèles ou des mélanges simples d'hydrocarbures, il n'existe pas à l'heure actuelle, à l'exception des modèles empiriques, de méthode pour rendre compte de la dégradation thermique des mélanges complexes, surtout, lorsque ces derniers sont enrichis en produits lourds. Au cours du craquage thermique, une huile produira à la fois des composés plus légers et des composés plus lourds que la charge initiale. En conséquence, les produits de pyrolyse seront un mélange complexe contenant des produits nouveaux et des composés non encore dégradés. Afin de pouvoir faire la distinction entre réactifs et produits, nous avons choisi de fractionner chaque huile en deux grandes fractions : la première (distillat 300- contenant des hydrocarbures légers de C6 à C16 et la seconde (résidu 300+ contenant des hydrocarbures et des produits polaires. Afin de simuler l'évolution thermique des huiles, nous avons réalisé une

  6. Laboratory Simulation of Rolling Contact Fatigue Cracks in Wind Turbine Bearings Using Hydrogen Infused 100Cr6 Bearing Steel

    DEFF Research Database (Denmark)

    Janakiraman, Shravan; West, Ole; Klit, Peder

    Premature fatigue failure is observed in rolling element bearings used in wind turbine components. It is believed that decomposed hydrogen from the lubricant diffuses into the surface of the bearing inner ring making it susceptible to failure. An attempt is made to simulate the formation of these...

  7. Modelisation des effets physico-techniques pour la conception des ...

    African Journals Online (AJOL)

    automatisation dans les installations industrielles a besoin d'une régulation automatique des commandes des processus technologiques pour lesquelles certaines contraintes sont à relever compte tenu des exigences des innovations scientifiques de ...

  8. Influence of enzymatic reactions on the electrochemical behavior of EN X2CrNiMo17-11-2 (AISI 316L) stainless steel in bio-corrosion: role of interfacial processes on the modification of the passive layer; Influence des reactions enzymatiques sur le comportement electrochimique de l'acier inoxydable ENX2CrNiMo17-11-2 (AISI 316L) en biocorrosion: role des processus interfaciaux sur la modification du film passif

    Energy Technology Data Exchange (ETDEWEB)

    Landoulsi, J

    2008-01-15

    The outstanding corrosion behavior of stainless steels (SS) results from the presence of thin oxide layer (some nanometers). In non sterile aqueous media, stainless steels may exhibit a non stable behavior resulting from interactions between microbial species and passive film. In fact, microorganisms can be deeply involved in the corrosion processes usually reported as Microbial Influenced Corrosion (MIC). They can induce the initiation or the acceleration of this phenomenon and they do so when organized in bio-films. From the electrochemical point of view, stainless steels showed an increase of the free corrosion potential (Ecorr) attributed to the bio-film settlement. The Eco' ennoblement was broadly reported in seawater and seems to be confirmed in fresh water according to recent findings. A considerable progress in the comprehension of MIC processes was related to the role of extracellular species, essentially enzymes. Many enzymatic reactions occurring in bio-films consist on using oxygen as electron acceptor to generate hydrogen peroxide and related species. The aim of this work is to understand the mechanisms involved in the electrochemical behavior of stainless steel according to an enzymatic approach in medium simulating fresh water. To this end, glucose oxidase was chosen to globalize aerobic activities of bio-films. Electrochemical measurements in situ and surface analysis allow the comprehension of the role and the nature of interfacial processes. Surface characterization was performed with the help of a new quantitative utilization of XPS analysis and AFM. Results show a significant evolution in term of morphology (surface organization), (ii) chemical composition (passive layer, adsorbed organic species) and (iii) chemical reaction (oxidation, dissolution, effect of enzyme). Finally, a new enzymatic system is proposed to mimic specific physicochemical conditions at the SS / bio-film interface, in particular enzymatic generation of oxidant species

  9. Finite element analysis of slot wall deformation in stainless steel and titanium orthodontic brackets during simulated palatal root torque.

    Science.gov (United States)

    Magesh, Varadaraju; Harikrishnan, Pandurangan; Kingsly Jeba Singh, Devadhas

    2018-04-01

    Torque applied on anterior teeth is vital for root positioning and stability. The aim of this study was to evaluate the detailed slot wall deformation in stainless steel (SS) and titanium (Ti) edgewise brackets during palatal root torque using finite element analysis. A finite element model was developed from a maxillary central incisor SS bracket (0.022 in). The generated torque values from an SS rectangular archwire (0.019 × 0.025 in) while twisting from 5° to 40° were obtained experimentally by a spine tester, and the calculated torque force was applied in the bracket slot. The deformations of the slot walls in both SS and Ti brackets were measured at various locations. There were gradual increases in the deformations of both bracket slot walls from the bottom to top locations. In the SS bracket slot for the 40° twist, the deformations were 9.28, 36.8, and 44.8 μm in the bottom, middle, and top slot wall locations, respectively. Similarly, in the Ti bracket slot for the 40° twist, the deformations were 39.2, 62.4, and 76.2 μm in the bottom, middle, and top slot wall locations, respectively. The elastic limits were reached at 28° for SS and at 37° for Ti. Both SS and Ti bracket slots underwent deformation during torque application. There are variations in the deformations at different locations in the slot walls and between the materials. Copyright © 2017 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  10. Properties of simulated welded joints of Cr-Mo steel following heat treatment in intercritical temperature range

    International Nuclear Information System (INIS)

    Sabun, L.B.; Vornovitskij, I.N.; Lukicheva, S.V.; Melamed, S.Eh.

    1975-01-01

    The parameters are determined of the welded joints heat treatment which permit to shorten the holp-up period due to the accelerating the process of the weld-stress release and the diffusion of carbon and alloying elements resulting in the equilibration of the weld metal chemical composition. The properties of an imitated welded joint of the 15KHM steel have been studied after various modes of heat treatment. The critical points are 740 and 875 deg C. The mechanical properties determination and the study of the strain hardening process are carried out with a high-temperature metallography plant. The modes of a low-temperature tempering and incomplete annealing are investigated within an intercritical range at temperatures of 750 to 780 deg C and a hold-up periods of to five minutes with a consecutive cooling in air or with the furnace respectively. The results of the studies have shown that with the decrease in the heat treatment temperature the strength, plasticity and also hardness of the welded joint zones prove to be to the standard of a sample treated conforming to the high tempering mode. In case of an incomplete annealing (770 to 780 deg C) the strength of the welded joint is maintained to the standard of the strength obtained at the high tempering, and the relative elongation value increases considerably at all the hold-up periods investigated. The strain-hardening process for the low-temperature normalizing and high tempering proceeds approximately equally. The fracture occurs at the deformation of 30 to 35% in microvolume, the relative elongation in that case being 12 to 13%

  11. Reheat cracking of austenitic stainless steels - pre-strain effect on intergranular damage; Fissuration en relaxation des aciers inoxydables austenitiques - influence de l'ecrouissage sur l'endommagement intergranulaire

    Energy Technology Data Exchange (ETDEWEB)

    Auzoux, Q

    2004-01-01

    Welding process induces strain in 316 stainless steel affected zones. Their microstructure was reproduce by rolling of three different steels (316L, 316L(N) et 316H). Traction, creep and relaxation tests were performed at 550 deg C and 600 deg C on smooth, notched and pre-cracked specimens. Pre-strain by rolling increases the hardness and the creep resistance because of the high dislocation density but decreases ductility because of the fast development of intergranular damage. This embrittlement leads to crack propagation during relaxation tests on pre-strained steels without distinction in respect to their carbon or nitrogen content. A new intergranular damage model was built using local micro-cracks measurements and finite elements analysis. Pre-strain effect and stress triaxiality ratio effect are reproduced by the modelling so that the reheat cracking risk near welds can now be estimated. (author)

  12. Simulation and Measurement of Through-the-Earth, Extremely Low-Frequency Signals Using Copper-Clad Steel Ground Rods

    OpenAIRE

    Damiano, Nicholas William; Yan, Lincan; Whisner, Bruce; Zhou, Chenming

    2017-01-01

    The underground mining environment can greatly affect radio signal propagation. Understanding how the earth affects signal propagation is a key to evaluating communications systems used during a mine emergency. One type of communication system is through-the-earth, which can utilize extremely low frequencies (ELF). This paper presents the simulation and measurement results of recent National Institute for Occupational Safety and Health (NIOSH) research aimed at investigating current injection...

  13. Numerical simulation of the cladding of a ferritic block with a stainless steel. Study of post-weld heat treatment

    International Nuclear Information System (INIS)

    Dupas, P.; Carayol, R.

    1994-06-01

    This report presents the calculation results of post-weld heat treatment, using the SYSWELD finite element program. Starting from the metallurgical and mechanical states obtained after welding, we performed a numerical heat treatment over the clad block. The principle is to relieve residual stresses by transforming elastic energy into plastic or viscoplastic energy. Increasing the temperature may lead to this result by decreasing yield stress, by creep or by changes of material properties due to structural transformations. Another way of relieving stresses is the transformation plasticity, but we don't use it in our simulation. Some experimental results lead us to believe we should have stresses from 200 to 300 MPa in the weld metal and from - 100 to 100 MPa in the HAZ, whatever are the stresses before heat treatment. Moreover, transverse and longitudinal stresses should have similar values and profile in depth. As in welding simulation, heat treatment calculations are two dimensional. They can be split in a thermo-metallurgical calculation followed by a mechanical one. The following parameters are studied : metallurgy, plastic and viscoplastic behaviour, plane strain or generalized plane strain model. The creep model used in SYSWELD has been more particularly studied. We also study the possibility to simplify calculations by simulating only the cooling, starting from no stresses at 610 deg C, which is a usual method in crack assessment. (authors). 23 refs., 52 figs., 3 annexes

  14. variabilite des productions et des revenus des exploitations

    African Journals Online (AJOL)

    3Centre de coopération internationale en recherche agronomique pour le développement (CIRAD), UMR Innovation,. Montpellier, France. Doubangolo COULIBALY, Email kone_b@yahoo.fr. RESUME. La durabilité des systèmes de production à base de coton dans un contexte de variabilité des prix aux producteurs et de ...

  15. Ion-bombardment effects on the fatigue life of stainless steel under simulated fusion first-wall conditions

    International Nuclear Information System (INIS)

    Kohse, G.E.

    1983-02-01

    An experiment which uses the MITR-II 5 MW research reactor to simulate several aspects of the anticipated environment of a fusion reactor first wall is described. Pressurized tube specimens are subjected simultaneously to stress and temperature cycling, surface bombardment by energetic helium and lithium ions and bulk irradiation by high-energy neutrons. Analysis of the samples is aimed primarily at determining the behavior of the ion bombarded surface layer, which has a depth of 2.5 μm, with particular reference to possible effects on the fatigue life of the material

  16. Loading and fracture response of CFRP-to-steel adhesively bonded joints with thick adherents – Part II: Numerical simulation

    DEFF Research Database (Denmark)

    Anyfantis, Konstantinos; Tsouvalis, Nicholas G.

    2013-01-01

    This work is focused on the numerical simulation of experimentally tested single lap joints, based on cohesive zone modeling techniques. Seven cases have been considered for analysis. The models were built in a 3-dimensional finite element space. The adherents were modeled with continuum elements...... the developed peel, in-plane and out-of-plane shear stresses over the adhesive area. Thus, the global measured response of all cases was justified by examining the stress fields and their variation through the loading history. © 2012 Elsevier Ltd. All rights reserved....

  17. The effect of residual thermal stresses on the fatigue crack growth of laser-surface-annealed AISI 304 stainless steel Part I: computer simulation

    International Nuclear Information System (INIS)

    Shiue, R.K.; Chang, C.T.; Young, M.C.; Tsay, L.W.

    2004-01-01

    The effect of residual thermal stresses on the fatigue crack growth of the laser-surface-annealed AISI 304 stainless steel, especially the effect of stress redistribution ahead of the crack tip was extensively evaluated in the study. Based on the finite element simulation, the longitudinal residual tensile stress field has a width of roughly 20 mm on the laser-irradiated surface and was symmetric with respect to the centerline of the laser-annealed zone (LAZ). Meanwhile, residual compressive stresses distributed over a wide region away from the LAZ. After introducing a notch perpendicular to the LAZ, the distribution of longitudinal residual stresses became unsymmetrical about the centerline of LAZ. High residual compressive stresses exist within a narrow range ahead of notch tip. The improved crack growth resistance of the laser-annealed specimen might be attributed to those induced compressive stresses. As the notch tip passed through the centerline of the LAZ, the residual stress ahead of the notch tip was completely reverted into residual tensile stresses. The existence of unanimous residual tensile stresses ahead of the notch tip was maintained, even if the notch tip extended deeply into the LAZ. Additionally, the presence of the residual tensile stress ahead of the notch tip did not accelerate the fatigue crack growth rate in the compact tension specimen

  18. Effect of inter-critically reheating temperature on microstructure and properties of simulated inter-critically reheated coarse grained heat affected zone in X70 steel

    International Nuclear Information System (INIS)

    Zhu, Zhixiong; Kuzmikova, Lenka; Li, Huijun; Barbaro, Frank

    2014-01-01

    This study investigated the influence of the inter-critical reheating temperature on the microstructure and mechanical properties of a coarse grained heat affected zone (CGHAZ) in an API 5L grade X70 pipeline steel seam weld. A Gleeble 3500 thermo-mechanical simulator was employed to duplicate particular weld thermal cycles in order to accurately assess specific regions of the weld HAZ. Detailed microstructural analysis, including investigation of the martensite–austenite (M–A) constituent, was performed using optical microscope (OM), scanning electron microscope (SEM) and selective etching techniques. It is shown that the fracture toughness of the CGHAZ is significantly reduced following exposure to a subsequent inter-critical thermal cycle. Fracture toughness gradually improves as the inter-critical temperature is increased, but does not return to the value of the original CGHAZ due to the presence of isolated large M–A particles and coarse microstructure. Significance of M–A particles to the HAZ fracture toughness is first related to the location of particles along prior austenite grain boundaries, followed by the size of individual M–A particles

  19. Role of Chloride in the Corrosion and Fracture Behavior of Micro-Alloyed Steel in E80 Simulated Fuel Grade Ethanol Environment

    Directory of Open Access Journals (Sweden)

    Olufunmilayo O. Joseph

    2016-06-01

    Full Text Available In this study, micro-alloyed steel (MAS material normally used in the production of auto parts has been immersed in an E80 simulated fuel grade ethanol (SFGE environment and its degradation mechanism in the presence of sodium chloride (NaCl was evaluated. Corrosion behavior was determined through mass loss tests and electrochemical measurements with respect to a reference test in the absence of NaCl. Fracture behavior was determined via J-integral tests with three-point bend specimens at an ambient temperature of 27 °C. The mass loss of MAS increased in E80 with NaCl up to a concentration of 32 mg/L; beyond that threshold, the effect of increasing chloride was insignificant. MAS did not demonstrate distinct passivation behavior, as well as pitting potential with anodic polarization, in the range of the ethanol-chloride ratio. Chloride caused pitting in MAS. The fracture resistance of MAS reduced in E80 with increasing chloride. Crack tip blunting decreased with increasing chloride, thus accounting for the reduction in fracture toughness.

  20. Tribological investigation of novel HDPE-HAp-Al2O3 hybrid biocomposites against steel under dry and simulated body fluid condition.

    Science.gov (United States)

    Nath, Shekhar; Bodhak, Subhadip; Basu, Bikramjit

    2007-10-01

    Among various biocompatible polymers, polyethylene based materials have received wider attention because of its excellent stability in body fluid, inertness, and easy formability. Attempts have been made to improve their physical properties (modulus/strength) to enable them to be used as load bearing hard tissue replacement applications. Among such attempts, high density polyethylene (HDPE)-hydroxyapatite (HAp) composite (HAPEX), has already been developed for total hip replacement (THR) acetabular cup and low load bearing bone tissue replacement. In the present work, alumina has been added as a partial replacement of HAp phase to improve the mechanical and tribological properties of the HAPEX composite. In an attempt to assess the suitability of the developed composite in THR application, the tribological properties against steel counterbody under both in air and simulated body fluid (SBF), have been investigated and efforts have been made to understand the wear mechanisms. The fretting wear study indicates the possibility of achieving extremely low COF (Coefficient of Friction approximately 0.09) as well as higher wear resistance (order of 10(-6) mm(3)/N m) with the newly developed composites in SBF. A low wear depth of approximately 4.6-5.3 microm is recorded, irrespective of fretting environment. The implication of the work is that optimal and combined addition of bioactive and bioinert ceramic filler to HDPE can provide a good opportunity to obtain hybrid biocomposites with better combination of physical properties (modulus, hardness) as well as low friction and high wear resistance.

  1. Effect of Low-Temperature Environment on Stress Corrosion Cracking Behavior of X80 Pipeline Steel in Simulated Alkaline Soil Solution

    Science.gov (United States)

    Xie, Fei; Wang, Dan; Wu, Ming; Yu, Chengxiang; Sun, Dongxu; Yang, Xu; Xu, Changhao

    2018-04-01

    The stress corrosion cracking (SCC) of X80 pipeline steel in simulated alkaline soil solution under different temperatures was investigated by slow-strain-rate testing, scanning electron microscopy and energy-dispersive spectroscopy. Results showed that the fracture was transgranular and brittle at 273 K to 278 K (0 °C to 5 °C), and the metal surface was dissolved by a large number of chloride ions. Furthermore, hydrogen embrittlement was caused by the hydrogen atom extended to the high-stress region. The fracture process was controlled by hydrogen-induced cracking, and SCC was highly sensitive at this stage. At 288 K to 298 K (15 °C to 25 °C), the fracture morphology was attributed to the mixed mode of ductile and brittle fractures, the fracture process was controlled by the mechanism of hydrogen-induced cracking and anodic dissolution, and the susceptibility to SCC decreased. When the temperature reached 308 K to 318 K (35 °C to 45 °C), the fracture was mainly intergranular and ductile, the fracture process was controlled by anodic dissolution, and SCC sensitivity was the smallest in this temperature range.

  2. Durée de vie des réseaux d’assainissement, modélisation Service life in sewerage system, simulation

    Directory of Open Access Journals (Sweden)

    Jauberthie R.

    2012-09-01

    Full Text Available La modélisation des systèmes physiques peut parfois être rendue difficile par la présence de bruits et perturbations. Lorsqu’il est possible de faire des hypothèses sur les caractéristiques de ces bruits et perturbations, les approches permettant d’inclure un modèle de ces perturbations dans le modèle du processus sont pertinentes et permettent entre autre de reconstruire l’état du processus. Cependant, ces hypothèses sont rarement satisfaites en pratique et, les modèles eux-mêmes sont parfois entachés d’erreurs. Néanmoins, ces grandeurs et paramètres non mesurés sont amenés à fluctuer entre des bornes relativement bien connues. C’est pourquoi il est naturel de se concentrer sur des estimateurs ensemblistes garantis en tout temps, dans un cadre déterministe à erreurs bornées. Ces méthodes relèvent de l’analyse par intervalles, qui est apparue pour la première fois dans l’ouvrage “Interval Analysis”, de R.E. Moore en 1966. Il a été montré que les modèles ensemblistes sont bien adaptés pour la détection d’aléas ou de défauts de processus et la formulation de diagnostics pertinents quant à l’amélioration du déroulement de processus. Après une présentation des modèles les plus courants, une analyse de l’endommagement des ouvrages d’assainissement de la ville de Rennes est entreprise. Ces ouvrages représentent le réseau unitaire et le réseau des eaux usées du système séparatif et sont constitués de matériaux à base cimentaire, armés ou non. L’endommagement est traduit par l’intermédiaire de différents indicateurs des propriétés des matériaux prélevés dans la ville. A ce jour, nous disposons d’une centaine de prélèvements effectués dans différentes rues et caractérisés par des dates de pose comprise entre 1892 à nos jours. Ainsi, dans ce travail, partant d’un modèle ensembliste du comportement des différents tronçons de canalisation des eaux usées, nous

  3. Low cycle fatigue behavior of hot-bent 347 stainless steel in a simulated PWR water environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun Ho; Seo, Myung Gyu; Jang, Chang Heui [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Hong, Jong Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Tae Soon [Central Research InstituteKorea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

    2016-11-15

    The effect of hot bending on the Low cycle fatigue (LCF) behavior of 347 SS was evaluated in Room temperature (RT) air and simulated Pressurized water reactor (PWR) water environments. The LCF life of 347 SS in PWR water was shorter than that in RT air for the as-received and hot-bent conditions. The LCF life of hot-bent 347 SS was relatively longer than that of the as-received condition in both RT air and PWR water. Microstructure analysis indicated development of dislocation structure near niobium carbide particles and increase in dislocation density for the hot-bent 347 SS. Such microstructure acted as barriers to dislocation movement during the LCF test, resulting in minimal hardening for the hot-bent 347 SS in RT air.

  4. Simulation and Measurement of Through-the-Earth, Extremely Low-Frequency Signals Using Copper-Clad Steel Ground Rods.

    Science.gov (United States)

    Damiano, Nicholas William; Yan, Lincan; Whisner, Bruce; Zhou, Chenming

    2017-01-01

    The underground mining environment can greatly affect radio signal propagation. Understanding how the earth affects signal propagation is a key to evaluating communications systems used during a mine emergency. One type of communication system is through-the-earth, which can utilize extremely low frequencies (ELF). This paper presents the simulation and measurement results of recent National Institute for Occupational Safety and Health (NIOSH) research aimed at investigating current injection at ELF, and in particular, ground contact impedance. Measurements were taken at an outside surface testing location. The results obtained from modeling and measurement are characterized by electrode impedance, and the voltage received between two distant electrodes. This paper concludes with a discussion of design considerations found to affect low-frequency communication systems utilizing ground rods to inject a current into the earth.

  5. Experimentation and numerical simulation of steel fibre reinforced concrete pipes; Experimentacion y simulacion numerica de tubos de hormigon con fibras

    Energy Technology Data Exchange (ETDEWEB)

    Fuente, A. de la; Domingues de Figueiredo, A.; Aguado, A.; Molins, C.; Chama Neto, P. J.

    2011-07-01

    The results concerning on an experimental and a numerical study related to SFRCP are presented. Eighteen pipes with an internal diameter of 600 mm and fibre dosages of 10, 20 and 40 kg/m3 were manufactured and tested. Some technological aspects were concluded. Likewise, a numerical parameterized model was implemented. With this model, the simulation of the resistant behaviour of SFRCP can be performed. In this sense, the results experimentally obtained were contrasted with those suggested by means MAP reaching very satisfactory correlations. Taking it into account, it could be said that the numerical model is a useful tool for the optimal design of the SFRCP fibre dosages, avoiding the need of the systematic employment of the test as an indirect design method. Consequently, the use of this model would reduce the overall cost of the pipes and would give fibres a boost as a solution for this structural typology. (Author) 27 refs.

  6. Analysis of Welding Zinc Coated Steel Sheets in Zero Gap Configuration by 3D Simulations and High Speed Imaging

    Science.gov (United States)

    Koch, Holger; Kägeler, Christian; Otto, Andreas; Schmidt, Michael

    Welding of zinc coated sheets in zero gap configuration is of eminent interest for the automotive industry. This Laser welding process would enable the automotive industry to build auto bodies with a high durability in a plain manufacturing process. Today good welding results can only be achieved by expensive constructive procedures such as clamping devices to ensure a defined gad. The welding in zero gap configuration is a big challenge because of the vaporised zinc expelled from the interface between the two sheets. To find appropriate welding parameters for influencing the keyhole and melt pool dynamics, a three dimensional simulation and a high speed imaging system for laser keyhole welding have been developed. The obtained results help to understand the process of the melt pool perturbation caused by vaporised zinc.

  7. Generic Methodology for Verification and Validation (GM-VV) to Support Acceptance of Models, Simulations and Data (Methodologie generale de verification et de validation (GM-VV) visant a soutenir l acceptation des modeles,