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Sample records for dual phase steel

  1. Dual phase steel for line pipe applications

    Energy Technology Data Exchange (ETDEWEB)

    Merwin, M.J. [United States Steel Corp., Research and Technology Centre, Monroeville, PA (United States)

    2005-07-01

    This paper presents the results of a laboratory study of 2 samples of commercially produced line pipe from the same melting grade. The chemistries of the steel samples were presented. The study was conducted in response to requests by the American Petroleum Institute (API) for line pipe steel with a yield-strength-to-tensile-strength ratio (Y/T) of 0.85 or less, for use in offshore installations. The United States Steel Corporation initiated this program to achieve lower Y/T for line pipe grades while maintaining robust processing capability and mechanical properties. Heat treated seamless tubular products are typically processed in a manner that can be readily modified to produce dual phase microstructures by applying intercritical soaking before quenching. The steel line pipe industry is interested in dual phase steel for use in reel barge pipe laying operations because the the yield strength of dual phase steel is lower than tensile strength. In this study, the compositions of commercially produced material already in use for the line pipe market were studied. The developed dual phase microstructures were found to be stable over a range of intercritical temperatures. Tempering temperature and small chemistry differences were found to have the greatest influence on properties. The toughness performance was found to be excellent in samples tempered at temperatures greater than 550 degrees C, a regime which produced materials with strength suitable for use in API X60 line pipe. An incomprehensible difference in tensile strength between steels of similar chemistry was also noted. Welding performance was examined through the simulation of 3 regions of the heat-affected zone. The heat-affected zone properties were not influenced by either intercritical or tempering temperature. The only significant factor was the peak temperature that was achieved in the thermal cycle. The hardness of the heat-affected zone increased continuously with increasing peak temperature

  2. Assuring microstructural homegeniety in dual phase and trip steels

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    Rivera-Diaz-del-Castillo, P.E.J.; Zwaag, S. van der [Faculty of Aerospace Engineering, Delft Univ., Delft (Netherlands)

    2004-11-01

    The presence of ferrite/pearlite bands in dual phase and TRIP assisted steels is a consequence of microchemical segregation which causes mechanical properties anisotropy. Such inhomogeneous phase distribution produces a lowering of the mechanical properties such as fracture behaviour. This anisotropy is commonly not accounted in micromechanics computations which often assume a random distribution of phases in the solid. The present paper deals with an integral model for this undesirable band formation accounting for the solute segregation caused by solidification, microcomponent diffusion present in the austenitisation process, and the nucleation of the transformed phase in segregated regions. In the present work, the model was applied to two industrial grade dual phase steels and two TRIP assisted steels. The influence of such parameters on band formation is summarised in a number of ''band prevention plots'', which are aimed at providing the optimum processing conditions for ferrite/pearlite band prevention. (orig.)

  3. Hyperplasticity effect under magnetic pulse straightening of dual phase steel

    Science.gov (United States)

    Falaleev, AP; Meshkov, VV; Shymchenko, A.

    2016-10-01

    An investigation of the behaviour of dual phase steel parts during straightening operations, by means of magnetic pulse treatment, is presented. The mechanical analysis of magnetic-pulse treatment for the straightening of thin-walled sheet metal parts produced from dual phase steel was performed, taking into account the effect of hyperplasticity under the influence of the magnetic field. Taking account of the causes of the hyperplasticity and thus the increase of material plasticity, it has been shown that the magnetic impulse gravity can be adjusted by controlling the operation modes. The dependence of the generated magnetic impulse gravity force on the electrical current strength inducted in this part was explored and used for analysis of the magnetic pulse straightening of dual phase steel part. Experimental results were obtained for thin-walled sheet metal part produced from dual phase steel DP 780. The results are used to demonstrate the material deformation under the influence of magnetic impulse gravity force considering the increase of material plasticity. The dependence of relative material deformation on the generated magnetic impulse gravity as well as on the current strength induced in this material was obtained and analyzed

  4. Simulation of springback and microstructural analysis of dual phase steels

    Science.gov (United States)

    Kalyan, T. Sri.; Wei, Xing; Mendiguren, Joseba; Rolfe, Bernard

    2013-12-01

    With increasing demand for weight reduction and better crashworthiness abilities in car development, advanced high strength Dual Phase (DP) steels have been progressively used when making automotive parts. The higher strength steels exhibit higher springback and lower dimensional accuracy after stamping. This has necessitated the use of simulation of each stamped component prior to production to estimate the part's dimensional accuracy. Understanding the micro-mechanical behaviour of AHSS sheet may provide more accuracy to stamping simulations. This work can be divided basically into two parts: first modelling a standard channel forming process; second modelling the micro-structure of the process. The standard top hat channel forming process, benchmark NUMISHEET'93, is used for investigating springback effect of WISCO Dual Phase steels. The second part of this work includes the finite element analysis of microstructures to understand the behaviour of the multi-phase steel at a more fundamental level. The outcomes of this work will help in the dimensional control of steels during manufacturing stage based on the material's microstructure.

  5. Strain partitioning in dual-phase steels containing tempered martensite

    Energy Technology Data Exchange (ETDEWEB)

    Han, Qihang, E-mail: hanqihang@baosteel.com [Research Institute, Baoshan Iron and Steel Co., Ltd., Shanghai 201900 (China); State Key Laboratory of Development and Application Technology of Automotive Steels (BaoSteel), Shanghai 201900 (China); Institute for Frontier Materials, Deakin University, Geelong, VIC. 3217 (Australia); Asgari, Alireza; Hodgson, Peter D.; Stanford, Nicole [State Key Laboratory of Development and Application Technology of Automotive Steels (BaoSteel), Shanghai 201900 (China)

    2014-08-12

    Tempering has been used as a method to develop a range of dual phase steels with the same martensite morphology and volume fraction, but containing phases with different relative strengths. These steels were used to examine the strain partitioning between the two constituent phases experimentally through mechanical testing and numerically through finite element modelling. It was found that increasing the differential in strength between the two phases not only produces regions of high strain, but also regions of low strain. On average, a larger difference in strength between the phases increased the strain carried by the softer phase. There was no discernible preferential strain localisation to the ferrite/martensite interface, with the regions of strain localisation being determined by the morphology of the microstructure. A direct correlation between the average strain in the ferrite, and the measured ductility has been found.

  6. Study of dynamic strain aging in dual phase steel

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, R.R.U. [Instituto Federal de Minas Gerais. Rua Pandia Calogeras, 898, Bauxita, Ouro Preto, MG (Brazil); Cunha, F.G.G. [Department of Metallurgical and Materials Engineering, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, Pampulha, Belo Horizonte, MG (Brazil); Gonzalez, B.M., E-mail: gonzalez@demet.ufmg.br [Department of Metallurgical and Materials Engineering, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, Pampulha, Belo Horizonte, MG (Brazil)

    2012-05-01

    Highlights: Black-Right-Pointing-Pointer Characterization of the high temperature mechanical behavior of a dual phase steel. Black-Right-Pointing-Pointer Determination of the effect of dynamic strain aging on the strain hardening rate. Black-Right-Pointing-Pointer Identification of the mechanism associated with dynamic strain aging. Black-Right-Pointing-Pointer The value of the interaction energy carbon-dislocation in ferrite was confirmed. - Abstract: The susceptibility to dynamic strain aging of a dual phase steel was evaluated by the variation of mechanical properties in tension with the temperature and the strain rate. The tensile tests were performed at temperatures varying between 25 Degree-Sign C and 600 Degree-Sign C and at strain rates ranging from 10{sup -2} to 5 Multiplication-Sign 10{sup -4} s{sup -1}. The studied steel presented typical manifestations related to dynamic strain aging: serrated flow (the Portevin-Le Chatelier effect) for certain combinations of temperature and strain rates; the presence of a plateau in the variation of yield stress with temperature; a maximum in the curves of tensile strength, flow stress, and work hardening exponent as a function of temperature; and a minimum in the variation of total elongation with temperature. The determined apparent activation energy values, associated with the beginning of the Portevin-Le Chatelier effect and the maximum in the variation of flow stress with temperature, were 83 kJ/mol and 156 kJ/mol, respectively. These values suggest that the mechanism responsible for dynamic strain aging in the dual phase steel is the locking of dislocations by carbon atoms in ferrite and that the formation of clusters and/or transition carbides and carbide precipitation in martensite do not interfere with the dynamic strain aging process.

  7. Ultra-Fine Grained Dual-Phase Steels

    Directory of Open Access Journals (Sweden)

    Matthias Militzer

    2012-10-01

    Full Text Available This paper provides an overview on obtaining low-carbon ultra-fine grained dual-phase steels through rapid intercritical annealing of cold-rolled sheet as improved materials for automotive applications. A laboratory processing route was designed that involves cold-rolling of a tempered martensite structure followed by a second tempering step to produce a fine grained aggregate of ferrite and carbides as the initial microstructure for rapid intercritical annealing. The intercritical annealing step was performed with heating and cooling rates of at least 100 °C/s and a holding time of 30 s. The intercritical temperature was selected to result in 20- 35% martensite in the final microstructures for C-Mn steels with carbon contents of 0.06, 0.12 and 0.17 wt%, respectively. The proposed processing routes produced an ultra-fine grained ferrite-martensite structure withgrain sizes of approximately 1 ?m for all three steels. The tensile strength of these ultra-fine grained dualphase steels can be increased by up to 200 MPa as compared to coarse-grained dual-phase steels while maintaining uniform elongation values. The rather narrow processing window necessary to obtain these properties was evaluated by determining the effect of intercritical annealing conditions on microstructure evolution. Further, the experimental results were confirmed with phase field simulations of austenite formation indicating that rapid heat treatment cycles are essential to obtain fine grained intercritical austenite that leads to martensite islands with sizes of 1 ?m and below in the final microstructure.

  8. Numerical cooling strategy design for hot rolled dual phase steel

    Energy Technology Data Exchange (ETDEWEB)

    Suwanpinij, Piyada; Prahl, Ulrich; Bleck, Wolfgang [RWTH Aachen (DE). Dept. of Ferrous Metallurgy (IEHK); Togobytska, Nataliya; Weiss, Wolf; Hoemberg, Dietmar [Weierstrass-Institut fuer Angewandte Analysis und Stochastik (WIAS) im Forschungsverbund Berlin e.V. (Germany)

    2010-10-21

    In this article, the Mo-Mn dual phase steel and its process parameters in hot rolling are discussed. The process window was derived by combining the experimental work in a hot deformation dilatometer and numerical calculation of process parameters using rate law models for ferrite and martensite transformation. The ferrite formation model is based on the Leblond and Devaux approach while martensite formation is based on the Koistinen- Marburger (K-M) formula. The carbon enrichment during ferrite formation is taken into account for the following martensite formation. After the completion of the parameter identification for the rate law model, the evolution of phases in multiphase steel can be addressed. Particularly, the simulations allow for predicting the preferable degree of retained strain and holding temperature on the run out table (ROT) for the required ferrite fraction. (orig.)

  9. QUANTITATIVE ANALYSIS OF BANDED STRUCTURES IN DUAL-PHASE STEELS

    Directory of Open Access Journals (Sweden)

    Benoit Krebs

    2011-05-01

    Full Text Available Dual-Phase (DP steels are composed of martensite islands dispersed in a ductile ferrite matrix, which provides a good balance between strength and ductility. Current processing conditions (continuous casting followed by hot and cold rolling generate 'banded structures' i.e., irregular, parallel and alternating bands of ferrite and martensite, which are detrimental to mechanical properties and especially for in-use properties. We present an original and simple method to quantify the intensity and wavelength of these bands. This method, based on the analysis of covariance function of binary images, is firstly tested on model images. It is compared with ASTM E-1268 standard and appears to be more robust. Then it is applied on real DP steel microstructures and proves to be sufficiently sensitive to discriminate samples resulting from different thermo-mechanical routes.

  10. Bauschinger effect and springback behavior of dual phase sheet steels

    Science.gov (United States)

    Ma, Hongwei

    2007-09-01

    With the increasing use of advanced high strength steels in the automotive industry, springback control has become a more critical issue. It is now realized that a more accurate simulation of springback has to take the Bauschinger effect into account, especially when sheet experiences complicated plastic deformation. In this study, the Bauschinger effect in dual-phase (DP) steels was investigated through tension-unloading-reloading tests. Fundamental mechanisms of the Bauschinger effect were examined via two special experiments: (i) TEM study of the dislocation distribution at the different plastic pre-strains in Bauschinger tests; and (ii) residual stress measurement after different tensile strains using in-situ neutron diffraction technology. To investigate the influence of the Bauschinger effect on springback, deep-draw bending tests were carried out with the different friction conditions. The experimental results of the tension-unloading-reloading tests show the Bauschinger effect in DP steel is much stronger than that in interfacial-free (IF) steel. TEM observation revealed very strong interactions between dislocations and martensite in DP steels. In-situ neutron diffraction tests show that the residual strains caused by inhomogeneous deformation of the two phases in DP steel after deformation are much higher than those in IF steels. The above results support the observation of a strong Bauschinger effect in DP steels. A composite model based on the analysis of internal stress shows further clearly that the residual stresses are the predominant mechanism of the Bauschinger effect in DP steels. A newly defined Bauschinger energy parameter (E beta) was found to be able to quantitatively describe this transient softening before reversed loading. The unloading responses showed the total recovery comes not only from elastic recovery but also from inelastic recovery. An effective unloading modulus was therefore introduced to reflect the inelastic recovery. Based on

  11. Phase analysis on dual-phase steel using band slope of electron backscatter diffraction pattern.

    Science.gov (United States)

    Kang, Jun-Yun; Park, Seong-Jun; Moon, Man-Been

    2013-08-01

    A quantitative and automated phase analysis of dual-phase (DP) steel using electron backscatter diffraction (EBSD) was attempted. A ferrite-martensite DP microstructure was produced by intercritical annealing and quenching. An EBSD map of the microstructure was obtained and post-processed for phase discrimination. Band slope (BS), which was a measure of pattern quality, exhibited much stronger phase contrast than another conventional one, band contrast. Owing to high sensitivity to lattice defect and little orientation dependence, BS provided handiness in finding a threshold for phase discrimination. Its grain average gave a superior result on the discrimination and volume fraction measurement of the constituent phases in the DP steel.

  12. Microstructure and mechanical properties of high strength and high toughness micro-laminated dual phase steels

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, M.D., E-mail: 15901022010@139.com [Special Steel Institute, Central Iron and Steel Research Institute, Beijing 100081 (China); School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Hu, J. [Special Steel Institute, Central Iron and Steel Research Institute, Beijing 100081 (China); School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Cao, W.Q., E-mail: cwq005211@163.com [Special Steel Institute, Central Iron and Steel Research Institute, Beijing 100081 (China); Dong, H. [Special Steel Institute, Central Iron and Steel Research Institute, Beijing 100081 (China)

    2014-11-17

    A series of steels with the micro-laminated dual phase microstructure were produced by hot rolling and air cooling processes in this study. Different volume fractions and morphology of the ferrite and martensite phases were obtained by adding different carbon contents in the steels containing 3 wt% aluminum. The microstructure of the dual phase steels was examined by optical microscopy (OM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). It was shown that the microstructure was composed of large ferrite and martensite lamellae. Small martensite laths and a miniscule amount of residual austenite were also found in the martensite phase. The tensile, impact and hardness tests revealed that the dual phase steels had an excellent combination of mechanical properties. The mechanical properties had a great relationship with the martensite volume fraction and the micro-laminated microstructure. The fractography of impact specimens was examined to explore the toughening mechanism of the micro-laminated dual phase steels.

  13. Strain Partitioning and Load Transfer in Constituent Phases in Dual-Phase Steels

    Science.gov (United States)

    Varshney, A.; Sangal, S.; Mondal, K.

    2016-09-01

    In this investigation, a new approach is proposed to calculate in situ true stress and strain in the constituent phases of dual-phase steel during deformation. The model incorporates modified law of mixture and constitutive equations. The model proposes that the deformation of martensite is pseudoelastic, and on little permanent deformation within the martensite allows the locked-in dislocation to release in the ferrite at the interface region of the ferrite and martensite. On application of the model to a set of dual-phase steels with varying microstructural parameters, it is established that the amount of strain partitioning is affected by the strength and amount of the hard phase, as well as grain size, work hardening ability, and yield strength of the softer phase. On the other hand, grain size, carbon content, and fraction and strength of martensite are the main factors controlling the load transfer among the phases.

  14. Nano-phases and corrosion resistance of C+Mo dual implanted steel

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The corrosion resistance of C+Mo dual-implanted H13 steel wasstudied using multi-sweep cyclic voltammetry. The phase formation conditions for corrosion resistance and its effects were researched. The super-saturation solid station solution of Mo+ and C+ atoms was formed in Mo+C dual implanted steel. Precipitate phase with nanometer size Fe2Mo, FeMo, MoC, Fe5C3 and Fe7C3 were formed in dual implanted layer. The passivation layer consisted of these nanometer phases. The corrosion resistance of the dual implanted layer was better than that of single Mo implantation. Jp of the Mo implanted sample is 0.55 times that of H13 steel. The corrosion resistance of the dual implantation was enhanced when ion dose increased. When the Mo+ ion dose was 6×1017/cm2 in the dual implantation, Jp of the dual implanted sample was only 0.11 times that in H13 steel. What is important is that pitting corrosion properties of dual implanted steel were improved obviously.

  15. Microstructural Characterization and Mechanical Properties of Powder Metallurgy Dual Phase Steel Preforms

    Institute of Scientific and Technical Information of China (English)

    K. Mahesh; S. Sankaran; P. Venugopal

    2012-01-01

    In order to improve the mechanical properties of powder metallurgy (P/M) ferrite-pearlite steel, a dual phase (DP) ferrite-martensite steel was produced through intercritical annealing of sintered P/M preforms. Mi-crostructures of the sintered and DP steels were examined with optical, scanning and transmission electron microscopes. Mechanical properties were evaluated through hardness measurements and compression tests. Microstructural studies revealed that sintered steel contained polygonal ferrite-pearlite while the DP steel contained polygonal, lath and acicular ferrite along with lath-type martensite as microstructural constituents. In DP steels, with increasing mean preform density, the microstructure contained fine and continuous network of martensite colonies with minimum porosity. The work hardening rate vs plastic strain plots (Jaoul-Crussard analysis) of both the steels revealed typical three stage deformation behaviour for low and high mean preform densities. Compression tests revealed that, DP P/M steel displayed higher strength-plasticity combination than the sintered steel.

  16. Effect of Intercritical Heat Treatment on the Abrasive Wear Behaviour of Plain Carbon Dual Phase Steel

    Science.gov (United States)

    Manoj, M. K.; Pancholi, V.; Nath, S. K.

    Dual phase (DP) steels have been prepared from low carbon steel (0.14% C) at intercritical temperature 740°C and time is varied from 1 minute to 30 minutes followed by water quenching. These steels have been characterized by optical microscopy, FE-SEM, hardness measurements, tensile properties and electron backscattered diffraction (EBSD) studies. Tensile properties of a typical dual phase steel are found to be 805 MPa ultimate tensile strength with 18% total elongation. Martensite volume fraction of D P steel (determined by EBSD technique) prepared at 740°C for 6 minutes is found to be 10.2% and the grain size of ferrite and martensite found to be 14.39 micron and 1.05 microns respectively. Abrasive wear resistance of dual phase steels has been determined by pin on drum wear testing machine. DP steels have been found to be 25% more wear resistant than that of normalized steel. Short intercritical heating time followed by water quenching gives higher wear resistance by virtue of smaller and well dispersed martensite island in the matrix of ferrite.

  17. Design of dual-phase Fe/Mn/C steel for low-temperature application

    Energy Technology Data Exchange (ETDEWEB)

    Kim, N.J.

    1981-09-01

    An investigation has been made to improve the impact properties of a dual phase Fe/1.5Mn/.06C steel for potential low temperature application. The research involved establishing the microstructure-property relationships, especially with regard to the morphology of the constituents. Dual phase processing was done in two ways, viz., controlled rolling and intercritical annealing of the as-hot-rolled structure.

  18. Correlation of FEA Prediction And Experiments On Dual-Phase Steel Automotive Rails

    Science.gov (United States)

    Du, C.; Chen, X. M.; Lim, T.; Chang, T.; Xiao, P.; Liu, S.-D.

    2007-05-01

    The North American Auto/Steel Partnership (A/SP) High-Strength Steel Forming Project Team has been studying the impact of advanced high-strength steels on stamping of structural components. Tooling was built to evaluate the effect of different grades of dual-phase steels on rail type stampings. The formed panels were laser scanned and the amount of springback was measured against the design intention. FEA simulation of the forming process was carried out to validate the numerical modeling techniques in the large and complex dual-phase steel stampings. The materials used in the study were Dual-Phase (DP) Steels DP600, DP780 and DP980. The FEA solver used was LS-Dyna version 971. The simulation results were correlated with the measurement data under various forming conditions including forming methods, trimming, binder and pad pressures. Reasonably good correlations were obtained across different grades of steels in terms of flange opening angles, wall opening angles, twist angles and dimensional deviations.

  19. Mechanical properties of fine-grained dual phase low-carbon steels based on dynamic transformation

    Institute of Scientific and Technical Information of China (English)

    Haiwei Xu; Wangyue rang; Zuqing Sun

    2008-01-01

    The fine grained dual phase (FG-DP) steel with ferrite grains of 2-4.5 μm and martensite islands smaller than 3 μm was obtained through the mechanism of deformation-enhanced ferrite transformation (DEFT). Mechanical properties of the steel were tested at room temperature. The results indicated that with a similar volume fraction of martensite (about 20vol%), FG-DP steel ex-hibited a superior combination of higher strength and more rapid strain hardening at low strains compared with the coarse-grained dual phase (CG-DP) steel obtained by critical annealing. The combination of higher strength, large elongation, and more rapid strain hardening of FG-DP steel can be attributed to the fine ferrite grain and finely dispersed martensite islands. In addition, the uniformly distributed martensite islands in FG-DP steel have smaller interspaeing compared with that of CG-DP steel. So, at the initial plastic deformation stage, the plastic deformation of ferrite was restrained and more pronounced load was transferred from ferrite to marten-site. The plastic deformation of martensite in FG-DP steel started earlier.

  20. Damage Evolution in Complex-Phase and Dual-Phase Steels during Edge Stretching.

    Science.gov (United States)

    Pathak, Nikky; Butcher, Cliff; Worswick, Michael James; Bellhouse, Erika; Gao, Jeff

    2017-03-27

    The role of microstructural damage in controlling the edge stretchability of Complex-Phase (CP) and Dual-Phase (DP) steels was evaluated using hole tension experiments. The experiments considered a tensile specimen with a hole at the center of specimen that is either sheared (sheared edge condition) or drilled and then reamed (reamed edge condition). The damage mechanism and accumulation in the CP and DP steels were systematically characterized by interrupting the hole tension tests at different strain levels using scanning electron microscope (SEM) analysis and optical microscopy. Martensite cracking and decohesion of ferrite-martensite interfaces are the dominant nucleation mechanisms in the DP780. The primary source of void nucleation in the CP800 is nucleation at TiN particles, with secondary void formation at martensite/bainite interfaces near the failure strain. The rate of damage evolution is considerably higher for the sheared edge in contrast with the reamed edge since the shearing process alters the microstructure in the shear affected zone (SAZ) by introducing work-hardening and initial damage behind the sheared edge. The CP microstructures were shown to be less prone to shear-induced damage than the DP materials resulting in much higher sheared edge formability. Microstructural damage in the CP and DP steels was characterized to understand the interaction between microstructure, damage evolution and edge formability during edge stretching. An analytical model for void evolution and coalescence was developed and applied to predict the damage rate in these rather diverse microstructures.

  1. Relation between microstructure and adhesion of hot dip galvanized zinc coatings on dual phase steel

    NARCIS (Netherlands)

    Song, G. M.; Vystavel, T.; De Hosson, J. Th M.; Sloof, W. G.; van der Pers, N.M.

    The microstructure of hot dip galvanized zinc coatings on dual phase steel was investigated by electron microscopy and the coating adhesion characterized by tensile testing. The zinc coating consists of a zinc layer and columnar zeta-FeZn13 particles on top of a thin inhibition layer adjacent to the

  2. Corrosion behavior of tempered dual-phase steel embedded in concrete

    Institute of Scientific and Technical Information of China (English)

    O(g)uzhan Kelestemur; Mustafa Aksoy; Servet Yddtz

    2009-01-01

    Dual-phase (DP) steels with different martensite contents were obtained by appropriate heat treatment of an SAE1010 structural carbon steel,which was cheap and widely used in the construction industry.The corrosion behavior of DP steels in con-crete was investigated under various tempering conditions.Intercritical annealing heat treatment was applied to the reinforcing steel to obtain DP steels with different contents of martensite.These DP steels were tempered at 200,300,and 400℃ for 45 min and then cooled to room temperature.Corrosion experiments were conducted in two stages.In the first stage,the corrosion potential of DP steels embedded in concrete was measured every day for a period of 30 d based on the ASTM C 876 standard.In the second stage,the anodic and cathodic polarization values of these steels were obtained and subsequently the corrosion currents were determined with the aid of cathodic polarization curves.It was observed that the amount of second phase had a definite effect on the corrosion behavior of the DP steel embedded in concrete.As a result of this study,it is found that the corrosion rate of the DP steel increases with an increase in the amount ofmartensite.

  3. Effect of Heat Treatment on Microstructure, Mechanical Properties and Fracture Behaviour of Ship and Dual Phase Steels%Effect of Heat Treatment on Microstructure, Mechanical Properties and Fracture Behaviour of Ship and Dual Phase Steels

    Institute of Scientific and Technical Information of China (English)

    Fatih Hayat; Htiseyin Uzun

    2011-01-01

    Grade A (GA) and high strength steel DH36 ship steels possessing different chemical compositions were used, and strength properties of GA steel and DH36 steel were compared. Additionally, 4 types of dual phase (DP) steels with different martensite volume fractions (MVFs) were produced from GA steel by means of heat treatment and they were compared with other steels through conducting mierostructure, microhardness, tensile and impact tests. The fracture surfaces of specimens (DH36, GA and DP steels) exposed to tensile and Charpy impact tests were investigated by scanning electron microscope. Furthermore, it was found that the specimens quenched from 800 and 900℃ had better strength than DH36 steel. The tensile test results indicated that the tensile strength of DP steel water quenched from 900℃ was 3 times that of GA steel and twice that of DH36 steel.

  4. Modification of Banding in Dual-Phase Steels via Thermal Processing

    DEFF Research Database (Denmark)

    Mukherjee, Krishnendu; Thomas, L. S.; Bos, C.

    2014-01-01

    The potential to utilize controlled thermal processing to minimize banding in a DP780 steel with 2 wt pct Mn was evaluated on samples processed on a Gleeble® 3500 thermomechanical processing simulator. All processing histories were selected to result in final dual-phase steel microstructures...... simulating microstructures achievable during annealing of initially cold rolled sheet. Strip samples were processed to evaluate the effects of heating rate, annealing time, annealing temperature, and cooling rate. The degree of banding in the final microstructures was evaluated with standard light optical...

  5. Finite element analysis of non-isothermal warm deep drawing of dual phase steel

    Directory of Open Access Journals (Sweden)

    Pepelnjak T.

    2016-01-01

    Full Text Available Improving the formability of the material is an important issue in the deep drawing process. Heating the material above its recrystallization temperature drastically increases formability but in the case of dual phase (DP steels it results in the loss of their mechanical properties. To improve the drawing ratio, only the heating of the flange region in the warm temperature range up to 300°C was studied on DP600 sheet steel by numerical simulation. Thermo-elastic-plastic FEM analysis of deep drawing at several drawing ratios was performed and compared with experimental results.

  6. Effect of vanadium on structure-property relations of dual phase fe/mn/si/0.1c steels

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, Alvin; Koo, J. Y.; Thomas, G.

    1981-11-01

    The role of vanadium on the structure-property relations of dual phase Fe/Mn/Si/0.1C steels has been investigated. After intercritical annealing at 800°C, the steels with and without V were either iced brine quenched or air cooled. The steels were also solution treated at 900°C and subsequently air cooled. Although V modified the resultant microstructure, especially the morphology of carbides, the corresponding mechanical properties are not significantly affected by the modified microstructures. It is concluded that V is not beneficial to such dual phase low carbon steels.

  7. Model Algorithm Research on Cooling Path Control of Hot-rolled Dual-phase Steel

    Institute of Scientific and Technical Information of China (English)

    Xiao-qing XU; Xiao-dong HAO; Shi-guang ZHOU; Chang-sheng LIU; Qi-fu ZHANG

    2016-01-01

    With the development of advanced high strength steel,especially for dual-phase steel,the model algorithm for cooling control after hot rolling has to achieve the targeted coiling temperature control at the location of downcoiler whilst maintaining the cooling path control based on strip microstructure along the whole cooling section.A cooling path control algorithm was proposed for the laminar cooling process as a solution to practical difficulties associated with the realization of the thermal cycle during cooling process.The heat conduction equation coupled with the carbon diffusion equation with moving boundary was employed in order to simulate temperature change and phase transfor-mation kinetics,making it possible to observe the temperature field and the phase fraction of the strip in real time. On this basis,an optimization method was utilized for valve settings to ensure the minimum deviations between the predicted and actual cooling path of the strip,taking into account the constraints of the cooling equipment′s specific capacity,cooling line length,etc.Results showed that the model algorithm was able to achieve the online cooling path control for dual-phase steel.

  8. Development of an aluminized multi-phase steel with dual phase properties for high temperature corrosion resistance applications

    Energy Technology Data Exchange (ETDEWEB)

    Mahieu, J.; Cooman, B.C. de [Lab. for Iron and Steelmaking, Dept. of Metallurgy and Materials Science, Ghent Univ., Zwijnaarde (Belgium); Maki, J. [Yawata R and D Lab., Nippon Steel Corp. (Japan); Fiorucci, M. [Galvalange Sarl, Dudelange (Luxembourg); Claessens, S. [OCAS NV, Zelzate (Belgium)

    2003-04-01

    A high strength, high Mn, Cr-Mo containing multi-phase steel grade was aluminized with a 90 wt% Al-10 wt% Si alloy coating, using a laboratory hot-dip simulator. The adhesion of the coating to the steel strip was evaluated and the microstructure of the as deposited material was assessed. The coated sheet steel was tested at high temperatures by monitoring the weight gain of the samples and their mechanical properties as a function of time. It was found that the thermal properties of the aluminized sheet were excellent. The analysis of the coating/substrate interface revealed the dissolution of brittle intermetallic phases, explaining the excellent high temperature resistance performance of the Al-Si coating up to temperatures as high as 900 C. In addition, the use of a continuous annealing cycle common in current aluminizing lines, resulted in a dual phase microstructure. (orig.)

  9. Microstructure-mechanical property relationships of dual-phase steel wire

    Science.gov (United States)

    Nakagawa, A. H.; Thomas, G.

    1985-05-01

    The high strain hardening rate and formability of dual-phase steels makes them promising choices for drawing into high strength wire. As the fundamental part of an alloy design project, dual-phase steels with several different martensite volume fractions, particle shapes, particle sizes, compositions, and crystallographic relations with the ferrite matrix were studied. They were wire drawn with true strains of up to 6.1. The initial microstructure, void formation tendency, drawability, and mechanical properties of the various steels were compared and correlated. The Fe-2Si-0.1C alloy was found to be the most promising with a suggested reduction in the carbon level to 0.06 to 0.08 pct. The double heat treatment which consists of quenching from austenite to martensite followed by intercritical annealing and quenching produced the best microstructure for drawing into wire. The annealing temperature should be adjusted to yield 25 to 30 vol pct martensite in the final microstructure. Stress relief after drawing provided a substantial increase in ductility without significant loss in strength.

  10. The Microstructure Evolution of Dual-Phase Pipeline Steel with Plastic Deformation at Different Strain Rates

    Science.gov (United States)

    Ji, L. K.; Xu, T.; Zhang, J. M.; Wang, H. T.; Tong, M. X.; Zhu, R. H.; Zhou, G. S.

    2017-07-01

    Tensile properties of the high-deformability dual-phase ferrite-bainite X70 pipeline steel have been investigated at room temperature under the strain rates of 2.5 × 10-5, 1.25 × 10-4, 2.5 × 10-3, and 1.25 × 10-2 s-1. The microstructures at different amount of plastic deformation were examined by using scanning and transmission electron microscopy. Generally, the ductility of typical body-centered cubic steels is reduced when its stain rate increases. However, we observed a different ductility dependence on strain rates in the dual-phase X70 pipeline steel. The uniform elongation (UEL%) and elongation to fracture (EL%) at the strain rate of 2.5 × 10-3 s-1 increase about 54 and 74%, respectively, compared to those at 2.5 × 10-5 s-1. The UEL% and EL% reach to their maximum at the strain rate of 2.5 × 10-3 s-1. This phenomenon was explained by the observed grain structures and dislocation configurations. Whether or not the ductility can be enhanced with increasing strain rates depends on the competition between the homogenization of plastic deformation among the microconstituents (ultra-fine ferrite grains, relatively coarse ferrite grains as well as bainite) and the progress of cracks formed as a consequence of localized inconsistent plastic deformation.

  11. Microstructure and properties of a C-Mn-Si-dual-phase steel

    Energy Technology Data Exchange (ETDEWEB)

    Klaar, H.J. (Technische Hochschule Aachen (Germany, F.R.). Gemeinschaftslaboratorium fuer Elektronenmikroskopie); El-Sesy, I.A.; Hussein, A.H.A. (Cairo Univ., Gizeh (Egypt). Dept. of Mining, Petroleum and Metallurgical Engineering)

    1990-01-01

    A study has been carried out on an Fe-0.11% C-1.58% Si-0.4% Mn-dual phase steel. The dual-phase microstructures and properties are significantly affected by both the intercritical temperature and cooling rate from ({alpha} + {gamma}) field. Upon rapid cooling (water or oil quench) from the temperature range 735-820deg C, the structure comprises ferrite + martensite. On the other hand, slow cooling (air cooling) from the temperature range 735-820deg C produces microstructures containing ferrite + martensite + pearlite/bainite and more favourable mechanical properties as: {sigma}{sub 0,2}=281-296 MPa, {sigma}{sub UTS}=632-690 MPa, TE=26-30% and continuous yielding behaviour. (orig.).

  12. A study on fatigue crack growth in dual phase martensitic steel in air environment

    Indian Academy of Sciences (India)

    K V Sudhakar; E S Dwarakadasa

    2000-06-01

    Dual phase (DP) steel was intercritically annealed at different temperatures from fully martensitic state to achieve martensite plus ferrite, microstructures with martensite contents in the range of 32 to 76%. Fatigue crack growth (FCG) and fracture toughness tests were carried out as per ASTM standards E 647 and E 399, respectively to evaluate the potential of DP steels. The crack growth rates (/) at different stress intensity ranges ( ) were determined to obtain the threshold value of stress intensity range ( th). Crack path morphology was studied to determine the influence of microstructure on crack growth characteristics. After the examination of crack tortuosity, the compact tension (CT) specimens were pulled in static mode to determine fracture toughness values. FCG rates decreased and threshold values increased with increase in vol.% martensite in the DP steel. This is attributed to the lower carbon content in the martensite formed at higher intercritical annealing (ICA) temperatures, causing retardation of crack growth rate by crack tip blunting and/or deflection. Roughness induced crack closure was also found to contribute to the improved crack growth resistance at higher levels of martensite content. Scanning electron fractography of DP steel in the near threshold region revealed transgranular cleavage fracture with secondary cracking. Results indicate the possibility that the DP steels may be treated to obtain an excellent combination of strength and fatigue properties.

  13. Formation of Austenite During Intercritical Annealing of Dual-Phase Steels

    Science.gov (United States)

    Speich, G. R.; Demarest, V. A.; Miller, R. L.

    1981-08-01

    The formation of austenite during intercritical annealing at temperatures between 740 and 900 °C was studied in a series of 1.5 pct manganese steels containing 0.06 to 0.20 pct carbon and with a ferrite-pearlite starting microstructure, typical of most dual-phase steels. Austenite formation was separated into three stages: (1) very rapid growth of austenite into pearlite until pearlite dissolution is complete; (2) slower growth of austenite into ferrite at a rate that is controlled by carbon diffusion in austenite at high temperatures (~85O °C), and by manganese diffusion in ferrite (or along grain boundaries) at low temperatures (~750 °C); and (3) very slow final equilibration of ferrite and austenite at a rate that is controlled by manganese diffusion in austenite. Diffusion models for the various steps were analyzed and compared with experimental results.

  14. Strain rate effects on the mechanical behavior of two Dual Phase steels in tension

    Science.gov (United States)

    Cadoni, E.; Singh, N. K.; Forni, D.; Singha, M. K.; Gupta, N. K.

    2016-05-01

    This paper presents an experimental investigation on the strain rate sensitivity of Dual Phase steel 1200 (DP1200) and Dual Phase steel 1400 (DP1400) under uni-axial tensile loads in the strain rate range from 0.001 s-1 to 600 s-1. These materials are advanced high strength steels (AHSS) having high strength, high capacity to dissipate crash energy and high formability. Flat sheet specimens of the materials having gauge length 10 mm, width 4 mm and thickness 2 mm (DP1200) and 1.25 mm (DP1400), are tested at room temperature (20∘C) on electromechanical universal testing machine to obtain their stress-strain relation under quasi-static condition (0.001 s-1), and on Hydro-Pneumatic machine and modified Hopkinson bar to study their mechanical behavior at medium (3 s-1, and 18 s-1) and high strain rates (200 s-1, 400 s-1, and 600 s-1) respectively. Tests under quasi-static condition are performed at high temperature (200∘C) also, and found that tensile flow stress is a increasing function of temperature. The stress-strain data has been analysed to determine the material parameters of the Cowper-Symonds and the Johnson-Cook models. A simple modification of the Johnson-Cook model has been proposed in order to obtain a better fit of tests at high temperatures. Finally, the fractographs of the broken specimens are taken by scanning electron microscope (SEM) to understand the fracture mechanism of these advanced high strength steels at different strain rates.

  15. The influence of martensite shape, concentration, and phase transformation strain on the deformation behavior of stable dual-phase steels

    Science.gov (United States)

    Bhattacharyya, A.; Sakaki, T.; Weng, G. J.

    1993-02-01

    A continuum model is developed to examine the influence of martensite shape, volume fraction, phase transformation strain, and thermal mismatch on the initial plastic state of the ferrite matrix following phase transformation and on the subsequent stress-strain behavior of the dual-phase steels upon loading. The theory is developed based on a relaxed constraint in the ductile matrix and an energy criterion to define its effective stress. In addition, it also assumes the martensite islands to possess a spheroidal shape and to be randomly oriented and homogenously dispersed in the ferrite matrix. It is found that for a typical water-quenched process from an intercritical temperature of 760 °C, the critical martensite volume fraction needed to induce plastic deformation in the ferrite matrix is very low, typically below 1 pct, regardless of the martensite shape. Thus, when the two-phase system is subjected to an external load, plastic deformation commences immediately, resulting in the widely observed “continuous yielding” behavior in dual-phase steels. The subsequent deformation of the dual-phase system is shown to be rather sensitive to the martensite shape, with the disc-shaped morphology giving rise to a superior overall response (over the spherical type). The stress-strain relations are also dependent upon the magnitude of the prior phase transformation strain. The strength coefficient h and the work-hardening exponent n of the smooth, parabolic-type stress-strain curves of the dual-phase system also increase with increasing martensite content for each selected inclusion shape. Comparison with an exact solution and with one set of experimental data indicates that the theory is generally within a reasonable range of accuracy.

  16. Effect of hardness of martensite and ferrite on void formation in dual phase steel

    DEFF Research Database (Denmark)

    Azuma, M.; Goutianos, Stergios; Hansen, Niels;

    2012-01-01

    The influence of the hardness of martensite and ferrite phases in dual phase steel on void formation has been investigated by in situ tensile loading in a scanning electron microscope. Microstructural observations have shown that most voids form in martensite by evolving four steps: plastic...... deformation of martensite, crack initiation at the martensite/ferrite interface, crack propagation leading to fracture of martensite particles and void formation by separation of particle fragments. It has been identified that the hardness effect is associated with the following aspects: strain partitioning...... between martensite and ferrite, strain localisation and critical strain required for void formation. Reducing the hardness difference between martensite and ferrite phases by tempering has been shown to be an effective approach to retard the void formation in martensite and thereby is expected to improve...

  17. Microstructure-Based RVE Approach for Stretch-Bending of Dual-Phase Steels

    Science.gov (United States)

    Huang, Sheng; He, ChunFeng; Zhao, YiXi

    2016-03-01

    Fracture behavior and micro-failure mechanism in stretch-bending of dual-phase (DP) steels are still unclear. Representative volume elements (RVE) have been proved to be an applicable approach for describing microstructural deformation in order to reveal the micro-failure mechanism. In this paper, 2D RVE models are built. The deformation behavior of DP steels under stretch-bending is investigated by means of RVE models based on the metallographic graphs with particle geometry, distribution, and morphology. Microstructural failure modes under different loading conditions in stretch-bending tests are studied, and different failure mechanisms in stretch-bending are analyzed. The computational results and stress-strain distribution analysis indicate that in the RVE models, the strain mostly occurs in ferrite phase, while martensite phase undertakes most stress without significant strain. The failure is the results of the deformation inhomogeneity between martensite phase and ferrite phase. The various appearance and growth of initial voids are different depending on the bending radius.

  18. Optimization as a support for design of hot rolling technology of dual phase steel strips

    Science.gov (United States)

    Szeliga, Danuta; Sztangret, Łukasz; Kusiak, Jan; Pietrzyk, Maciej

    2013-05-01

    The objective of the paper was performing of the sensitivity analysis of the model used for design of manufacturing technology for auto body parts made of the Advanced High Strength Steels (AHSS). Dual phase steel was considered as an example. The sensitivity analysis was performed to evaluate the importance of all variables as far as their influence on the finishing rolling temperature and grain size. The phase composition after cooling was also considered. An arbitrary hot rolling process characterized only by a number of passes and cooling conditions between passes, as well as by laminar cooling parameters, was selected for the analysis. Metamodel of the rolling cycle was developed to decrease the computing costs for the optimization task. Modified Avrami equation was used for modelling phase transformations during cooling. Such process parameters as the initial temperature, interpass times, heat exchange coefficients and rolling velocities were selected as optimization variables for the rolling process. Parameters of the thermal cycles were selected as the optimization variables for the laminar cooling process. Achieving the required phase composition of product was the optimization objective function. Optimization was performed using various techniques, including methods inspired by nature optimization.

  19. Nanoindentation study of ferrite–martensite dual phase steels developed by a new thermomechanical processing

    Energy Technology Data Exchange (ETDEWEB)

    Mazaheri, Yousef, E-mail: y.mazaheri@ma.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Faculty of Engineering, Bu-Ali Sina University, Hamedan 65178-38695 (Iran, Islamic Republic of); Kermanpur, Ahmad; Najafizadeh, Abbas [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2015-07-15

    Dual phase (DP) steels consisting different volume fractions of ferrite and martensite and different ferrite grain size were produced by a new route utilizing cold-rolling and subsequent intercritical annealing of ferrite/martensite duplex starting structure at 770 °C for different times. Scanning electron microscopy has been supplemented by nanoindentation and tensile test to follow microstructural changes and their correlations to the variation in phase's hardness and mechanical properties. The results showed that longer holding times resulted in coarser and softer ferrite grains in DP microstructures. Martensite nanohardness variation with holding time is related to change in its carbon content. Mechanical properties such as strength, elongation and toughness are well correlated with the martensite/ferrite hardness ratio.

  20. The mechansims by which solute nitrogen affects phase transformations and mechanical properties of automotive dual-phase sheet steel

    Science.gov (United States)

    Brown, Tyson W.

    Dual-phase steels have seen increased use in automotive applications in recent years, in order to meet the goals of weight reduction and occupant safety. Variations in nitrogen content that may be encountered in steel sourced from a basic oxygen furnace process compared to an electric arc furnace process require that dual-phase steel producers understand the ways that nitrogen affects processing and properties. In the current work, the distribution of nitrogen was investigated in a dual-phase steel with a base chemistry of 0.1 C, 2.0 Mn, 0.2 Cr, 0.2 Mo (wt pct) across a range of nitrogen contents (30-159 ppm) with Al (0.2 and 0.08 wt pct), and Ti (0.02 wt pct) additions used for precipitation control of nitrogen amounts. The distribution of nitrogen amongst trapping sites, including precipitates, grain boundaries, dislocations, and interstitial sites (away from other types of defects) was determined from a combination of electrolytic dissolution, internal friction, and three-dimensional atom probe tomography experiments. Various mechanisms by which different amounts and locations of nitrogen affect phase transformations and mechanical properties were identified from quantitative metallography, dilatometric measurement of phase transformations, tensile testing, and nanoindentation hardness testing. Results indicate nitrogen that is not precipitated with Ti or Al (free nitrogen) partitions to austenite (and thus martensite) during typical intercritical annealing treatments, and is mostly contained in Cottrell atmospheres in martensite. Due to the austenite stabilizing effect of nitrogen, the presence of free nitrogen during intercritical annealing leads to a higher austenite fraction in certain conditions. Thus, the presence of free nitrogen in a dual-phase microstructure will lead to an increase in tensile and yield strengths from both an increase in martensite fraction, and an increase in martensite hardness due to solid solution strengthening. Despite the presence

  1. Mechanism of Secondary Hardening in Rapid Tempering of Dual-Phase Steel

    Science.gov (United States)

    Saha, Dulal Chandra; Nayak, Sashank S.; Biro, Elliot; Gerlich, Adrian P.; Zhou, Y.

    2014-12-01

    Dual-phase steel with ferrite-martensite-bainite microstructure exhibited secondary hardening in the subcritical heat affected zone during fiber laser welding. Rapid isothermal tempering conducted in a Gleeble simulator also indicated occurrence of secondary hardening at 773 K (500 °C), as confirmed by plotting the tempered hardness against the Holloman-Jaffe parameter. Isothermally tempered specimens were characterized by analytic transmission electron microscopy and high-angle annular dark-field imaging. The cementite (Fe3C) and TiC located in the bainite phase of DP steel decomposed upon rapid tempering to form needle-shaped Mo2C (aspect ratio ranging from 10 to 25) and plate-shaped M4C3 carbides giving rise to secondary hardening. Precipitation of these thermodynamically stable and coherent carbides promoted the hardening phenomenon. However, complex carbides were only seen in the tempered bainite and were not detected in the tempered martensite. The martensite phase decomposed into ferrite and spherical Fe3C, and interlath-retained austenite decomposed into ferrite and elongated carbide.

  2. Influence of silicon on the microstructures, mechanical properties and stretch-flangeability of dual phase steels

    Institute of Scientific and Technical Information of China (English)

    Le-yu Zhou; Dan Zhang; Ya-zheng Liu

    2014-01-01

    Uniaxial tension tests and hole-expansion tests were carried out to determine the influence of silicon on the microstructures, me-chanical properties, and stretch-flangeability of conventional dual-phase steels. Compared to 0.03wt%silicon, the addition of 1.08wt%sili-con induced the formation of finer ferrite grains (6.8μm) and a higher carbon content of martensite (Cm≈0.32wt%). As the silicon level in-creased, the initial strain-hardening rate (n value) and the uniform elongation increased, whereas the yield strength, yield ratio, and stretch-flangeability decreased. The microstructures were observed after hole-expansion tests. The results showed that low carbon content martensite (Cm≈ 0.19wt%) can easily deform in coordination with ferrite. The relationship between the mechanical properties and stretch-flangeability indicated that the steel with large post-uniform elongation has good stretch-flangeability due to a closer plastic incom-patibility of the ferrite and martensite phases, which can effectively delay the production and decohesion of microvoids.

  3. Fatigue properties of X80 pipeline steels with ferrite/bainite dual-phase microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zuo-peng [Key Lab of Metastable Materials Science & Technology and College of Materials Science & Engineering, Yanshan University, Qinhuangdao 066004 (China); Qiao, Gui-ying [Key Lab of Metastable Materials Science & Technology and College of Materials Science & Engineering, Yanshan University, Qinhuangdao 066004 (China); Key Lab of Applied Chemistry of Hebei Province and School of Environment and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); Tang, Lei [Key Lab of Applied Chemistry of Hebei Province and School of Environment and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); Zhu, Hong-wei; Liao, Bo [Key Lab of Metastable Materials Science & Technology and College of Materials Science & Engineering, Yanshan University, Qinhuangdao 066004 (China); Xiao, Fu-ren, E-mail: frxiao@ysu.edu.cn [Key Lab of Metastable Materials Science & Technology and College of Materials Science & Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2016-03-07

    Fatigue properties are important parameters for the safety design and security evaluation of gas transmission pipelines. In this work, the fatigue life at different stresses of full-thickness X80 pipeline steel plates with a ferrite/bainite dual-phase microstructure was investigated using a MTS servo-hydraulic universal testing machine; the fatigue crack propagation rate was examined with CT specimens by using an INSTRON 8874 testing machine. Results indicate that fatigue life increases as maximum stress decreases; as the maximum stress decreases to the maximum operating stress (440 MPa), the fatigue life is approximately 4.2×10{sup 5} cycles. The fatigue crack of the full-thickness fatigue life specimens is generated at the surface of rolled steel plates and then the crack propagates and grows inward until a fracture is formed. During fatigue crack growth, a transitional turning point appears in the curve of da/dN with ΔK in the Paris region. The transitional turning point that divides the Paris region to two stages is approximately ΔK≅30 MPa m{sup 1/2}. The change in the growth rate (da/dN) is related to the variation of the crack path and in the fracture mode because of the possible microstructural sensitivity of fatigue crack propagation behavior. This study also discussed the effect of duple phase ferrite/bainite microstructure on fatigue crack initiation and propagation.

  4. Microstructure-properties correlation in fiber laser welding of dual-phase and HSLA steels

    Energy Technology Data Exchange (ETDEWEB)

    Saha, D.C., E-mail: dcsaha@uwaterloo.ca [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1 (Canada); Westerbaan, D.; Nayak, S.S. [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1 (Canada); Biro, E. [ArcelorMittal Global Research, 1390 Burlington Street East, Hamilton, ON, Canada L8N 3J5 (Canada); Gerlich, A.P.; Zhou, Y. [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1 (Canada)

    2014-06-01

    Similar and dissimilar welds of dual-phase (DP) and high strength low alloy (HSLA) steels were made by fiber laser welding (FLW). The welds were characterized with respect to microstructure, micro- and nano-hardness, and tensile properties. The fusion zone (FZ) in the DP welds consisted of fully martensitic structure; whereas HSLA and dissimilar weld FZ microstructure were mixture of martensite and bainite. Analytical transmission electron microscopy (TEM) confirmed bainite structures containing bainitic ferrite laths with intralath and interlath cementite. Precipitation of single variant carbides inside the bainitic ferrite laths were confirmed by measuring the interplanar spacing. The cooling rate in the FZ, estimated using Rosenthal equation, and continuous-cooling-transformation diagrams corroborated the microstructure formed. Nanoindentation was used to verify the hardness of these individual microconstituents, since a much lower nano-hardness for bainite (4.11 GPa) was observed compared to martensite (6.57 GPa) phase. Tensile failure occurred in the tempered area of the heat affected zone (HAZ) in the DP steel welded, which was confirmed by typical cup-like dimple fracture; likewise failure in the HSLA base metal, which occurred in dissimilar and HSLA welds, indicated distinctive dimple and shear dimple ductile morphology.

  5. Friction drilling of dual phase steels; Taladrado por friccion en aceros de doble fase

    Energy Technology Data Exchange (ETDEWEB)

    Nardi, D.; Lopez de Lacalle, L. N.; Lamikiz, A.

    2012-11-01

    This work describes the experimental study of the friction drilling process in dual phase (DP) steels, with yield strengths from 600 to 800 Mpa. The optimal machining conditions with different thicknesses was assessed through controlled tests at different rotation speeds and feed rates. On one hand, the torque and the thrust force were computed and monitorized. On the other hand, the dimensional tolerances of the holes were evaluated. Another topic of interest inherent to this special technique is the temperature level reached during the friction process which is crucial when it comes to development of microstructural transformations. This thermal condition can transform the mechanical properties of material near the hole and the burr. (Author)

  6. Effects of microstructure on fatigue crack growth behavior in cold-rolled dual phase steels

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shengci [School of Materials Science and Engineering, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Kang, Yonglin, E-mail: kangylin@ustb.edu.cn [School of Materials Science and Engineering, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Kuang, Shuang [Technical Research Institute, Shougang Corporation, Ltd., Beijing 100043 (China)

    2014-08-26

    Fatigue crack growth behaviors of cold-rolled dual phase steels with different microstructures were investigated at room temperature. The ferrite–martensite dual-phase microstructure was obtained by intercritical annealing. Fatigue crack growth (FCG) behaviors were described by both the Paris model and a new exponential model; fatigue fractography and surface morphology near the fracture were arrested by scanning electron microscopy (SEM); the relationship between macroscopic and microcosmic FCG rate was analyzed quantificationally. The results showed that both the models can be used to describe the fatigue crack growth rate of the samples rather well; fatigue striations and secondary cracks were observed in the fracture surface at stable expanding region (II), while the fracture at rapid expanding region (III) combined dimple and quasi-cleavage morphology; the roughness of fracture surface and the degree of secondary cracking increased with an increase in martensite content, leading to a higher threshold value. Moreover, the changes of microcosmic FCG rate were smoother than that of the macroscopic FCG rate.

  7. Microstructure and dynamic tensile behavior of DP600 dual phase steel joint by laser welding

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Danyang, E-mail: dongdanyang@mail.neu.edu.cn [College of Science, Northeastern University, No. 11, Lane 3, WenHua Road, HePing District, Shenyang 110819 (China); Liu, Yang, E-mail: liuyang@mail.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110819 (China); Yang, Yuling, E-mail: yulingyang@mail.neu.edu.cn [College of Science, Northeastern University, No. 11, Lane 3, WenHua Road, HePing District, Shenyang 110819 (China); Li, Jinfeng, E-mail: lijinfengboda@163.com [College of Science, Northeastern University, No. 11, Lane 3, WenHua Road, HePing District, Shenyang 110819 (China); Ma, Min, E-mail: sharon6789@163.com [College of Science, Northeastern University, No. 11, Lane 3, WenHua Road, HePing District, Shenyang 110819 (China); Jiang, Tao, E-mail: tao.jiang906@yahoo.com [College of Science, Northeastern University, No. 11, Lane 3, WenHua Road, HePing District, Shenyang 110819 (China)

    2014-01-31

    Dual phase (DP) steels have been widely used in the automotive industry to reduce vehicle weight and improve car safety. In such applications welding and joining have to be involved, which would lead to a localized change of the microstructure and property, and create potential safety and reliable issues under dynamic loading. The aim of the present study is to examine the rate-dependent mechanical properties, deformation and fracture behavior of DP600 steel and its welded joint (WJ) produced by Nd:YAG laser welding over a wide range of strain rates (0.001–1133 s{sup −1}). Laser welding results in not only significant microhardness increase in the fusion zone (FZ) and inner heat-affected zone (HAZ), but also the formation of a softened zone in the outer HAZ. The yield strength (YS) of the DP600 steel increases and the ultimate tensile strength (UTS) remains almost unchanged, but the ductility decreases after welding. The DP600 base metal (BM) and WJ are of positive strain rate sensitivity and show similar stress–strain response at all studied strain rates. The enhanced ductility at strain rates ranging from 1 to 100 s{sup −1} is attributed to the retardation of the propagation of plastic strain localization due to the positive strain rate sensitivity and the thermal softening caused by deformation induced adiabatic temperature rise during dynamic tensile deformation. The tensile failure occurs in the inner HAZ of the joint and the distance of failure location from the weld centerline decreases with increasing strain rate. The mechanism for the changing failure location can be related to the different strain rate dependence of the plastic deformation behavior of the microstructures in various regions across the joint. The DP600 WJ absorbs more energy over the whole measured strain rates than that of the BM due to the higher strength at the same strain when the deformation only up to 10% is considered.

  8. Effect of deformation on microstructure and mechanical properties of dual phase steel produced via strip casting simulation

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Z.P., E-mail: zuileniwota@126.com [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Kostryzhev, A.G. [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Stanford, N.E. [Institute of Frontier Materials, Deakin University, Geelong, Victoria 3216 (Australia); Pereloma, E.V. [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Electron Microscopy Centre, University of Wollongong, Wollongong, NSW 2519 (Australia)

    2016-01-10

    The strip casting is a recently appeared technology with a potential to significantly reduce energy consumption in steel production, compared to hot rolling and cold rolling. However, the quantitative dependences of the steel microstructure and mechanical properties on strip casting parameters are unknown and require investigation. In the present work we studied the effects of strain and interrupted cooling temperature on microstructure and mechanical properties in conventional dual phase steel (0.08C–0.81Si–1.47Mn–0.03Al wt%). The strip casting process was simulated using a Gleeble 3500 thermo-mechanical simulator. The steel microstructures were studied using optical, scanning and transmission electron microscopy. Mechanical properties were measured using microhardness and tensile testing. Microstructures consisting of 40–80% polygonal ferrite with remaining martensite, bainite and very small amount of Widmanstätten ferrite were produced. Deformation to 0.17–0.46 strain at 1050 °C refined the prior austenite grain size via static recrystallisation, which led to the acceleration of ferrite formation and the ferrite grain refinement. The yield stress and ultimate tensile strength increased with a decrease in ferrite fraction, while the total elongation decreased. The improvement of mechanical properties via deformation was ascribed to dislocation strengthening and grain boundary strengthening. - Highlights: • A processing route of strip casting was developed to produce dual phase steel. • The mechanical properties were comparable to cold rolled and hot rolled DP steels.

  9. Austenite formation during intercritical annealing in C-Mn cold-rolled dual phase steel

    Institute of Scientific and Technical Information of China (English)

    李声慈; 康永林; 朱国明; 邝霜

    2015-01-01

    Two different kinds of experimental techniques were used to in-situ study the austenite formation during intercritical annealing in C-Mn dual phase steel. The microstructure evolution was observed by confocal laser scanning microscope, and the austenite isothermal and non-isothermal transformation kinetics were studied by dilatometry. The results indicate that banded structure is produced for the reason of composition segregation and the competition between recrystallization and phase transformation. Austenite prefers to nucleate not only at ferrite/ferrite grain boundaries, but also inside the grains of ferrite. Furthermore, the austenitizing process is accomplished mainly via migration of the existing austenite/ferrite interface rather than nucleation of new grains. The incubation process can be divided into two stages which are controlled by carbon and manganese diffusion, respectively. During the incubation process, the nucleation rate of austenite decreases, and austenite growth changes from two-dimensional to one-dimensional. The partitioning coefficient, defined as the ratio of manganese content in the austenite to that in the adjacent ferrite, increases with increasing soaking time.

  10. Modelling the Process Chain of Cold Rolled Dual Phase Steel for Automotive Application

    Science.gov (United States)

    Ramazani, A.; Prahl, U.

    This project aims to develop a virtual process chain for the production of components out of cold-rolled dual-phase (DP) steel. The simulation chain starts with cold-rolled strip. During intercritical annealing process all relevant steps like recrystallization, austenite formation and grain growth, ferrite and martensite transformation including bainite fractions and quasi-tempering during hot dip coating and coiling are taken into account. Concerning the final mechanical properties transformation induced micro eigenstresses are described as well as strain partitioning on microscale during cold forming. This multi-scale and process-spanning approach enables the local properties in the part for varying composition and processing conditions. Thus, it can be used for the knowledge driven design and optimization of tailored material and process. To describe all the steps along the process chain, various simulation programs have been linked. By comparison of simulation and experimental results the predictability of this approach can be shown an in a later stage the integrative simulation approach will be further developed towards application for material and process design.

  11. Characterization of dual-phase steel microstructure by combined submicrometer EBSD and EPMA carbon measurements.

    Science.gov (United States)

    Pinard, Philippe T; Schwedt, Alexander; Ramazani, Ali; Prahl, Ulrich; Richter, Silvia

    2013-08-01

    Electron backscatter diffraction (EBSD) and electron probe microanalysis (EPMA) measurements are combined to characterize an industrial produced dual-phase steel containing some bainite fraction. High-resolution carbon mappings acquired on a field emission electron microprobe are utilized to validate and improve the identification of the constituents (ferrite, martensite, and bainite) performed by EBSD using the image quality and kernel average misorientation. The combination eliminates the ambiguity between the identification of bainite and transformation-induced dislocation zones, encountered if only the kernel average misorientation is considered. The detection of carbon in high misorientation regions confirms the presence of bainite. These results are corroborated by secondary electron images after nital etching. Limitations of this combined method due to differences between the spatial resolution of EBSD and EPMA are assessed. Moreover, a quantification procedure adapted to carbon analysis is presented and used to measure the carbon concentration in martensite and bainite on a submicrometer scale. From measurements on reference materials, this method gives an accuracy of 0.02 wt% C and a precision better than 0.05 wt% C despite unavoidable effects of hydrocarbon contamination.

  12. Effect of continuous annealing parameters on the mechanical properties and microstructures of a cold rolled dual phase steel

    Institute of Scientific and Technical Information of China (English)

    Shuang Kuang; Yong-lin Kang; Hao Yu; Ren-dong Liu

    2009-01-01

    A cold rolled dual phase (DP) steel with the C-Si-Mn alloy system was trial-produced in the laboratory, utilizing a Glee-ble-3800 thermal simulator. The effects of continuous annealing parameters on the mechanical properties and microstructures of the DP steel were investigated by mechanical testing and microstructure observation. The results show that soaking between 760 and 820 ℃ for more than 80 s, rapid cooling at the rate of more than 30℃/s from the quenching temperature between 620 and 680℃, and overaging lower than 300°C are beneficial for the mechanical properties of DP steels. An appropriate proportion of the two phases is one of the key factors for the favorable properties of DP steels. If the volume fraction of martensite and, thereby, free dislocations are deficient, the tensile strength and n value of DP steels will decrease, whereas, the yield slrength will increase. But if the volume frac-tion of martensite is excessive to make it become a dominant phase, the yield and tensile strength will increase, whereas, the elonga-tion will decrease obviously. When rapid cooling rate is not fast enough, pearlite or cementite will appear, which will degrade the mechanical properties. Even though martensite is sufficient, if it is decomposed in high temperature tempering, the properties will be unsatisfied.

  13. Microstructure and Fatigue Properties of Laser Welded DP590 Dual-Phase Steel Joints

    Science.gov (United States)

    Xie, Chaojie; Yang, Shanglei; Liu, Haobo; Zhang, Qi; Cao, Yaming; Wang, Yuan

    2017-08-01

    In this paper, cold-rolled DP590 dual-phase steel sheets with 1.5 mm thickness were butt-welded by a fiber laser, and the evolution and effect on microhardness, tensile property and fatigue property of the welded joint microstructure were studied. The results showed that the base metal is composed of ferrite and martensite, with the martensite dispersed in the ferrite matrix in an island manner. The microstructure of the weld zone was lath-shaped martensite that can be refined further by increasing the welding speed, while the heat-affected zone was composed of ferrite and tempered martensite. The microhardness increased with increasing welding speed, and the hardness reached its highest value—393.8 HV—when the welding speed was 5 m/min. Static tensile fracture of the welded joints always occurred in the base metal, and the elongation at break was more than 16%. The conditional fatigue limits of the base metal and the weld joints were 354.2 and 233.6 MPa, respectively, under tension-tension fatigue tests with a stress rate of 0.1. After observation of the fatigue fracture morphology, it was evident that the fatigue crack of the base metal had sprouted into the surface pits and that its expansion would be accelerated under the action of a secondary crack. The fatigue source of the welded joint was generated in the weld zone and expanded along the martensite, forming a large number of fatigue striations. Transient breaking, which occurred in the heat-affected zone of the joint as a result of the formation of a large number of dimples, reflected the obvious characteristics of ductile fracture.

  14. An Overview of Dual-Phase Steels: Advances in Microstructure-Oriented Processing and Micromechanically Guided Design

    Science.gov (United States)

    Tasan, C. C.; Diehl, M.; Yan, D.; Bechtold, M.; Roters, F.; Schemmann, L.; Zheng, C.; Peranio, N.; Ponge, D.; Koyama, M.; Tsuzaki, K.; Raabe, D.

    2015-07-01

    Dual-phase (DP) steel is the flagship of advanced high-strength steels, which were the first among various candidate alloy systems to find application in weight-reduced automotive components. On the one hand, this is a metallurgical success story: Lean alloying and simple thermomechanical treatment enable use of less material to accomplish more performance while complying with demanding environmental and economic constraints. On the other hand, the enormous literature on DP steels demonstrates the immense complexity of microstructure physics in multiphase alloys: Roughly 50 years after the first reports on ferrite-martensite steels, there are still various open scientific questions. Fortunately, the last decades witnessed enormous advances in the development of enabling experimental and simulation techniques, significantly improving the understanding of DP steels. This review provides a detailed account of these improvements, focusing specifically on (a) microstructure evolution during processing, (b) experimental characterization of micromechanical behavior, and (c) the simulation of mechanical behavior, to highlight the critical unresolved issues and to guide future research efforts.

  15. Comparison Between Different Processing Schedules for the Development of Ultrafine-Grained Dual-Phase Steel

    Science.gov (United States)

    Karmakar, Anish; Sivaprasad, S.; Nath, S. K.; Misra, R. D. K.; Chakrabarti, Debalay

    2014-05-01

    A comparative study was carried out on the development of ultrafine-grained dual-phase (DP) (ferrite-martensite) structures in a low-carbon microalloyed steel processed using two thermomechanical processing routes, (i) intercritical deformation and (ii) warm-deformation and intercritical annealing. The samples were deformed using Gleeble3500® simulator, maintaining a constant total strain ( ɛ = 1) and strain rate ( = 1/s). Evolution of microstructure and micro-texture was investigated by SEM, TEM, and EBSD. Ultrafine-grained DP structures could be formed by careful selection of deformation temperature, T def (for intercritical deformation) or annealing temperature, T anneal (for warm-deformation and annealing). Overall, the ferrite grain sizes ranged from 1.5 to 4.0 μm, and the sizes and fractions of the uniformly distributed fine-martensitic islands ranged from 1.5 to 3.0 μm and 15 to 45 pct, respectively. Dynamic strain-induced austenite-to-ferrite transformation followed by continuous (dynamic) recrystallization of the ferrite dictated the grain refinement during intercritical deformation, while, continuous (static) recrystallization by pronounced recovery dictated the grain refinement during the warm-deformation and the annealing. Regarding intercritical deformation, the samples cooled to T def indicated finer grain size compared with the samples heated to T def, which are explained in terms of the effects of strain partitioning on the ferrite and the heating during deformation. Alpha-fiber components dominated the texture in all the samples, and the fraction of high-angle boundaries (with >15 deg misorientation) increased with the increasing T def or T anneal, depending on the processing schedule. Fine carbide particles, microalloyed precipitates and austenitic islands played important roles in defining the mechanism of grain refinement that involved retarding conventional ferrite recrystallization and ferrite grain growth. With regard to the intercritical

  16. Multi-scale invertigation of the relationship between the microstructure and mechanical properties in dual phase steels

    Science.gov (United States)

    Zhang, Fan

    Dual phase steel alloys belong to the first generation of advanced high strength steels that are widely used in the automotive industry to form body structure and closure panels of vehicles. A deeper understanding of the microstructural features, such as phase orientation and morphology are needed in order to establish their effect on the mechanical performance and to design a material with optimized attributes. In this work, our goal is to establish what kind of relationship exist between the mechanical properties and the microstructural representation of dual phase steels obtained from experimental observations. Microstructure in different specimens are characterized with advanced experimental techniques as optical microscopy, scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction pattern, scanning probe microscopy, and nanoindentation. Nanoindentation, Vickers hardness and tensile testing are conducted to reveal a multi-scale mechanical performance on original material and also specimens under a variety combinations of temperatures, cooling rates, and rolling conditions. To quantify the single phase properties in each sample, an inverse method is adopted using experimental nanoindentation load-depth curves to obtain tensile stress-strain curves for each phase, and the inverse results were verified with the true stress-strain curves from tensile tests. This work also provides the insight on spatial phase distribution of different phases through a 2-point correlation statistical methodology and relate to material strength and formability. The microstructure information is correlated with the results of mechanical tests. The broken surfaces from tensile testing are analyzed to discover the fracture mechanism in relation to martensite morphology and distribuion. Viscoplastic self-consistent fast Fourier Transformation simulations is also used to compute efficiently the local and the homogenized viscoplastic response of the

  17. Characterization of dual-phase steels obtained by hot-rolling; Caracterizacion de aceros dual-phase obtenidos por laminacion en caliente

    Energy Technology Data Exchange (ETDEWEB)

    Monsalve, A.; Artigas, A.; Castro, F.; Colas, R.; Houbaert, Y.

    2011-07-01

    Samples were obtained from C-Mn-Si steel available in the market. Through a hot rolling and coiling process, it was possible to obtain Dual-Phase steel with microstructural and mechanical properties in the theoretical range typical of this material. The thermomechanical process consisted of a strong reduction by multiples pass of hot rolling at temperatures above Ar{sub 3}, controlled-cooling the sheets during 5 s (at a rate of 20 degree centigrade/s) in the equilibrium range {alpha}+{gamma} Temperature Ar{sub 3} measured by differential scanning calorimetry was 890 degree centigrade. Quenching was then carried out in the coiling temperatures range (500-675 degree centigrade), cooling the samples in accordance to an established curve that corresponds to the actual cooling curve of a coil. The microstructural characterization of the samples obtained was carried out by optical microscopy, scanning electron microscopy and atomic force microscopy. Additionally, texture measurements were carried out by X-ray diffraction in order to study the resulting orientations due to the finishing rolling temperature and coiling temperature, determining the influence on these parameters of the different texture components. The microstructural results were complemented with the normal and planar anisotropy indexes measured in according to the ASTM E-517 standard. The intensities of the different texture components were correlated with the values of anisotropy indexes, finding that it is possible to obtain only a slightly enhancement in the normal anisotropy index through an appropriate combination of finish rolling and coiling temperatures. (Author) 16 refs.

  18. Study on microstructures and work hardening behavior of ferrite-martensite dual-phase steels with high-content martensite

    Directory of Open Access Journals (Sweden)

    Xiurong Zuo

    2012-12-01

    Full Text Available A kind of medium-carbon low-alloy dual-phase steels with high-content martensite produced by intercritical annealing at 785-830 ºC for 10-50 minutes were studied in aspect of microstructures and work hardening behavior using SEM and tensile testing machine. The experimental results showed that the work hardening of the studied steels obeyed the two-stage work hardening mechanism, whose work hardening exponent of the first stage was higher than that of the second stage. The work hardening exponent increased with increasing the intercritical annealing temperature and time. For series A steel intercritically annealed at 785 ºC with starting microstructure of ferrite plus pearlite, austenite nucleated at the pearlite colonies, so the holding time of only 50 minutes can increase the work hardening exponent obviously. For series B steel with starting microstructure of martensite, austenite nucleated at lath interfaces, lath colony boundaries of primary martensite and carbides, accelerating the formation of austenite, so holding time for 30 minutes made the work hardening exponent increase obviously. High work hardening rate during initial plastic deformation (<0.5% strain was observed.

  19. Effects of overaging temperature on the microstructure and properties of 600 MPa cold-rolled dual-phase steel

    Institute of Scientific and Technical Information of China (English)

    Chun-fu Kuang; Zhi-wang Zheng; Gong-ting Zhang; Jun Chang; Shen-gen Zhang; Bo Liu

    2016-01-01

    C–Mn steels prepared by annealing at 800°C for 120 s and overaging at 250–400°C were subjected to pre-straining (2%) and bak-ing treatments (170°C for 20 min) to measure their bake-hardening (BH2) values. The effects of overaging temperature on the microstructure, mechanical properties, and BH2 behavior of 600 MPa cold-rolled dual-phase (DP) steel were investigated by optical microscopy, scanning electron microscopy, and tensile tests. The results indicated that the martensite morphology exhibited less variation when the DP steel was overaged at 250–350°C. However, when the DP steel was overaged at 400°C, numerous non-martensite and carbide particles formed and yield-point elongation was observed in the tensile curve. When the overaging temperature was increased from 250 to 400°C, the yield strength increased from 272 to 317 MPa, the tensile strength decreased from 643 to 574 MPa, and the elongation increased from 27.8%to 30.6%. Furthermore, with an increase in overaging temperature from 250 to 400°C, the BH2 value initially increases and then decreases. The maximum BH2 value of 83 MPa was observed for the specimen overaged at 350°C.

  20. Soldadura de aceros dual phase en chapa fina: GMAW, PAW y RSW Welding of dual phase steel sheet: GMAW, PAW and RSW

    Directory of Open Access Journals (Sweden)

    Hernán Svoboda

    2011-06-01

    Full Text Available Los aceros Dual Phase (DP han encontrado recientemente una fuerte aplicación en elementos estructurales en la industria automotriz, debido a la necesidad de disminuir peso. La soldadura de estos materiales cobra particular importancia considerando su aplicación estructural y los procesos relacionados en su fabricación. En particular la soldadura de resistencia por punto (RSW y semiautomática con alambre macizo y protección gaseosa (GMAW son ampliamente utilizados en la industria automotriz. El proceso de soldadura por plasma (PAW se caracteriza, entre los procesos de soldadura por arco, por ser el de mayor densidad de energía, presentando particular interés en aplicaciones de la industria automotriz (tailor welded blanks. El objetivo del presente trabajo fue estudiar la evolución microestructural y las propiedades de aceros DP soldados mediante los procesos RSW, GMAW y PAW. A este fin, se soldaron cuatro grados de aceros DP con resistencias mecánicas de 550, 700 y 850 MPa en espesores de 1 y 1,3 mm mediante los mencionados procesos. Se caracterizaron las microestructuras y se determinaron las propiedades mecánicas de las uniones soldadas para cada caso. Para los tres procesos se obtuvieron uniones soldadas de calidad satisfactoria. Se observó para todas las soldaduras, que en la ZAC se produce una disminución de la dureza por debajo del valor del material base, relacionada a la descomposición de la fase martensítica. Las soladuras por arco fueron las más afectadas.Dual Phase steels (DP have been used recently as an interesting option for structural elements, specialy in automotive industry, due to weight reduce requirements. Welding of these materials becomes particularly important considering their application as structural elements and the related manufacturing methods. In particular resistance spot welding (RSW and gas metal arc welding (GMAW are widely used in the automotive manufacturing. The plasma arc welding (PAW has the

  1. Unraveling the Initial Microstructure Effects on Mechanical Properties and Work-Hardening Capacity of Dual-Phase Steel

    Science.gov (United States)

    Mirzadeh, Hamed; Alibeyki, Mohammad; Najafi, Mostafa

    2017-10-01

    Ferritic-martensitic, dual-phase (DP) microstructures with different size, morphology, and distribution of martensite were produced by altering the initial microstructures using heat treatment and thermomechanical processing routes. It was revealed that the strength, ductility, and work-hardening rate of DP steels strongly depend on the volume fraction and the morphology of the martensite phase. In this regard, the fine-grained DP microstructure showed a high work-hardening ability toward an excellent combination of strength and ductility. Such a microstructure can be readily obtained by intercritical annealing of an ultrafine grained (UFG) microstructure, where the latter can be produced by cold-rolling followed by tempering of a martensite starting microstructure. Conclusively, the enhancement of mechanical properties of DP steels through microstructural refinement was found to be more beneficial compared with increasing the volume fraction of martensite. Finally, it was also demonstrated that the work-hardening rate analysis based on the instantaneous (incremental) work-hardening exponents might be an advantageous approach for characterizing DP steels along with the conventional approaches.

  2. Microstructure and mechanical properties of laser welded dissimilar DP600/DP980 dual-phase steel joints

    Energy Technology Data Exchange (ETDEWEB)

    Farabi, N. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Chen, D.L., E-mail: dchen@ryerson.ca [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Zhou, Y. [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada)

    2011-01-21

    Research highlights: > Laser welding results in a significant hardness rise in the fusion zone, but the formation of a soft zone in the heat-affected zone. > A characteristic unsymmetrical hardness profile is observed across the dissimilar joint. > Yield point phenomenon with only stage III strain hardening occurs after welding. > Fatigue life at higher stress amplitudes is equivalent to that of DP600 steel despite slightly lower fatigue limit. - Abstract: The use of dual phase (DP) steels in the automobile industry unavoidably involves welding and dynamic loading. The aim of this investigation was to evaluate the microstructural change and mechanical properties of laser welded dissimilar DP600/DP980 steel joints. The dissimilar joints showed a significant microstructural change from nearly full martensite in the fusion zone (FZ) to the unchanged ferrite-martensite dual-phase microstructure in the base metal. The welding resulted in a significant hardness increase in the FZ but the formation of a soft zone in the heat-affected zone (HAZ). The dissimilar welded joints were observed to exhibit a distinctive unsymmetrical hardness profile, yield-point-like phenomenon, and single-stage work hardening characteristic, with yield strength and work hardening rate lying in-between those of DP600 and DP980 base metals, and ultimate tensile strength equivalent to that of DP600 base metal. Although the welded joints showed a lower fatigue limit than the base metals, the fatigue life of the welded joints at higher stress amplitudes was almost the same as that of the DP600 base metal. The welded joints failed in the soft zone at the DP600 side under tensile loading and fatigue loading at the higher stress amplitudes. Fatigue crack initiation occurred from the specimen surface and crack propagation was characterized by typical fatigue striation together with secondary cracks.

  3. Effect of adding powder on joint properties of laser penetration welding for dual phase steel and aluminum alloy

    Science.gov (United States)

    Zhou, D. W.; Liu, J. S.; Lu, Y. Z.; Xu, S. H.

    2017-09-01

    The experiments of laser penetration welding for dual phase steel and aluminum alloy were carried out, and the effect of adding Mn or Si powder on mechanical properties and microstructure of the weld was investigated. Some defects, such as spatter, inclusion, cracks and softening in heat affected zone (HAZ), can be avoided in welding joints, and the increased penetration depth is obtained by adding Mn or Si powder. The average tensile-shear strength of Si-added joint is 3.84% higher than that of Mn-added joint, and the strength of both joints exceeds that of no-added joint. In the case of adding Mn powder, small amount of liquid Al is mixed into steel molten pool, and the Al content increases in both sides of the weld, which leads to the increased weld width in aluminum molten pool. Thus, transverse area increases in jointing steel to aluminum, which is significant for the improved tensile-shear strength of joints. As far as adding Si powder is concerned, it is not the case, the enhancement of the joint properties benefits from improvement of metallurgical reaction.

  4. Investigation of intercritical heat treatment temperature effect on microstructure and mechanical properties of dual phase (DP steel

    Directory of Open Access Journals (Sweden)

    Mohammad Davari

    2017-06-01

    Full Text Available In the present study, the effect of intercritical heat treatment temperature on the tensile properties and work hardening behavior of ferritic-martensitic dual-phase steel have been investigated utilizing tensile test, microhardness measurement and microscopic observation. Plain carbon steel sheet with a thickness of 2 mm was heat treated at 760, 780, 800, 820 and 840 °C intercritical temperatures. The results showed that martensite volume fraction (Vm increases from 32 to 81%with increasing temperature from 760 to 840 °C. The mechanical properties of samples were examined by tensile and microhardness tests. The results revealed that yield strength was increased linearly with the increase in Vm, but the ultimate strength was increased up to 55% Vm and then decreased afterward. Analyzing the work hardening behavior in term of Hollomon equation showed that in samples with less than 55% Vm, the work hardening took place in one stage and the work hardening exponent increased with increasing Vm. More than one stage was observed in the work hardening behavior when Vm was increased. The results of microhardness test showed that microhardness of the martensite is decreased by increase in heat treatment temperature while the ferrite microhardness is nearly constant for all heat-treated samples.

  5. Fracture mechanisms in dual phase steels based on the acicular ferrite + martensite/austenite microstructure

    Science.gov (United States)

    Poruks, Peter

    The fracture mechanisms of low carbon microalloyed plate steels based on the acicular ferrite + marten site/austenite microstructure (AF + M/A) are investigated. The final microstructure consists of a dispersed phase of submicron equi-axed martensite particles with a bainitic ferrite matrix. A series of plates with M/A volume fractions of 0.076--0.179 are studied. Brittle fracture is investigated by Instrumented Charpy impact testing of samples at -196°C and subsequent metallography. The M/A particles are identified as the crack nucleation sites and the cleavage fracture stress calculated to be 2400 MPa in a complete AF microstrucuture. This value is significantly larger than in steels that contain significant proportions of conventional bainite. Standard Charpy and Instrumented Charpy impact testing is conducted through a temperature range from -80 to + 22°C to study ductile fracture behaviour. The total absorbed energy is separated into energies of crack nucleation and of crack propagation. It is found that the energy of crack nucleation is weakly dependent on the volume fraction of M/A and completely independent of temperature over the range studied. The crack propagation energy varies significantly with both variables, decreasing with increased volume fraction of M/A and with decreasing temperature. The peak load in the instrumented Charpy data is used to calculate the dynamic fracture toughness, KId, which is found to be 105--120 MPa-m1/2. The void nucleation and void growth stages of ductile fracture are studied by metallographic examination of tensile bars. The sites of void nucleation are identified as inclusions and M/A particles. Voids nucleate at the M/A particles by decohesion of the particle-matrix interface. A constant void nucleation strain of epsilon = 0.90 +/- 0.05 is measured for all of the samples independent of the volume fraction of M/A. A stress-based criterion is used to predict void nucleation and the interface strength is determined to be

  6. Effect of solidification rate on microstructure evolution in dual phase microalloyed steel.

    Science.gov (United States)

    Kostryzhev, A G; Slater, C D; Marenych, O O; Davis, C L

    2016-10-19

    In steels the dependence of ambient temperature microstructure and mechanical properties on solidification rate is not well reported. In this work we investigate the microstructure and hardness evolution for a low C low Mn NbTi-microalloyed steel solidified in the cooling rate range of 1-50 Cs(-1). The maximum strength was obtained at the intermediate solidification rate of 30 Cs(-1). This result has been correlated to the microstructure variation with solidification rate.

  7. Microstructure and Mechanical Properties of V-Nb Microalloyed Ultrafine-Grained Dual-Phase Steels Processed Through Severe Cold Rolling and Intercritical Annealing

    Science.gov (United States)

    Papa Rao, M.; Subramanya Sarma, V.; Sankaran, S.

    2016-12-01

    Ultrafine-grained (UFG) dual-phase (DP) steel was produced by severe cold rolling (true strain of 2.4) and intercritical annealing of a low carbon V-Nb microalloyed steel in a temperature range of 1003 K to 1033 K (730 °C to 760 °C) for 2 minutes, and water quenching. The microstructure of UFG DP steels consisted of polygonal ferrite matrix with homogeneously distributed martensite islands (both of size hardening. Analysis of work hardening behavior of the UFG DP steels through modified Crussard-Jaoul analysis showed a continuously varying work hardening rate response which could be approximated by 2 or 3 linear regimes. The transmission electron microscopy analysis on post tensile-tested samples indicated that these regimes are possibly related to the work hardening of ferrite, lath, and twin martensite, respectively.

  8. Study of Laser Welding of HCT600X Dual Phase Steels

    Directory of Open Access Journals (Sweden)

    Švec Pavol

    2014-12-01

    Full Text Available The effects of beam power and welding speed on microstructure, microhardnes and tensile strength of HCT600X laser welded steel sheets were evaluated. The welding parameters influenced both the width and the microstructure of the fusion zone and heat affected zone. The welding process has no effect on tensile strength of joints which achieved the strength of base metal and all joints fractured in the base metal.

  9. Effect of grain size on the mechanical properties of dual phase Fe/Si/C steels

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, J.H.

    1983-08-01

    For an Fe/2Si/0.1C steel with an intermediate quenching heat treatment, it was found that as the prior austenite grain size is refined, significant improvements in total elongation, reduction in area and impact toughness can be achieved, while uniform elongation, yield and tensile strengths are not affected. These improvements are analyzed in terms of microstructure and fracture characteristics. The cleavage cracks propagate nearly straight without deviation at the ferrite/martensite interfaces within the sub-units of the DFM structure, but change their path at high angle sub-unit boundaries. The crack is less likely to be deflected at the ferrite/martensite interface because the interface is coherent. Comparison of optical micrographs and SEM fractographs has shown that there is close agreement between the sub-unit size and cleavage facet size. The observations lead to the conclusion that the sub-unit size is the basic microstructure unit controlling the fracture behavior of DFM steels produced by the intermediate quenching heat treatment. A controlled rolling process was undertaken to obtain grain refined DFM steels. Results showed that this produces micro-duplex structures with attractive mechanical properties in an economicl way.

  10. Separation of nucleation and growth of voids during tensile deformation of a dual phase steel using synchrotron microtomography

    Energy Technology Data Exchange (ETDEWEB)

    Requena, Guillermo, E-mail: guillermo.requena@tuwien.ac.at [INSA-Lyon, MATEIS CNRS UMR5510, F-69621 Villeurbanne (France); Maire, Eric; Leguen, Claire [INSA-Lyon, MATEIS CNRS UMR5510, F-69621 Villeurbanne (France); Thuillier, Sandrine [LIMATB, Université de Bretagne-Sud, rue de Saint Maudé, BP 92116, 56321 Lorient Cedex (France)

    2014-01-01

    The damage evolution in a DP980 dual phase steel is followed in situ by synchrotron microtomography during tensile deformation focusing on the effect that the triaxiality, induced by different sample geometries, exerts on damage formation and damage evolution. The growth of existing voids is separated from the voids nucleated between consecutive deformation steps using three-dimensional image analysis. The experimental results are correlated with those obtained by finite element analysis using a Gurson–Tvergaard–Needleman framework with a Chu and Needleman formulation to introduce the effect of nucleation of cavities. A relatively simple way to determine the nucleation parameters is proposed based on the volume of nucleated voids obtained from the tomographies. The evolution of the total volume fraction of cavities obtained from the calculations shows a good agreement with the experiments for the notched samples and reflects the effect of triaxiality on damage. Contrarily to experiments, the calculated accumulated volume fraction of nucleated voids does not reflect the effect of triaxiality suggesting the necessity to implement this parameter in the nucleation model.

  11. Constitutive Relations Analyses of Plastic Flow in Dual-Phase Steels to Elucidate Structure-Strength-Ductility Correlations

    Science.gov (United States)

    Saimoto, S.; Timokhina, I. B.; Pereloma, E. V.

    2017-07-01

    The structure-strength characterization is typically performed by correlating the structure with x-ray, electron, or atomic imaging devices to the bulk mechanical tensile parameters of yield stress and the plastic yielding response. The problem is that structure parameters embedded in the stress-strain data cannot be revealed without an analyzable constitutive relation. New functional slip-based constitutive formulation with precise digital fitting parameters can replicate the measured data with at least two loci. Thus, this study examines the possibility of identifying the mechanical response as a result of the various microstructure components. The key parameter, the mean slip distance, can be calibrated from the initial work-hardening slope at 0.2% strain from which all the fit parameters can be determined. In this process, a newly derived friction stress is defined to separate the yield phenomenon from the plastic strains beyond yield-point elongation. This methodology has been applied to dual-phase steel specimens that resulted in excellent predictive correlations with prior structure-strength characterization. Hence, the structure-strength-ductility changes resulting from processing conditions can be more precisely surmised from mechanical testing. Thus, a method to delineate the nanostructure evolution with deformation using mesoscopic mechanical parameters has been introduced.

  12. Effect of Carbon Distribution During the Microstructure Evolution of Dual-Phase Steels Studied Using Cellular Automata, Genetic Algorithms, and Experimental Strategies

    Science.gov (United States)

    Halder, Chandan; Karmakar, Anish; Hasan, Sk. Md.; Chakrabarti, Debalay; Pietrzyk, Maciej; Chakraborti, Nirupam

    2016-12-01

    The development of ferrite-martensite dual-phase microstructures by cold-rolling and intercritical annealing of 0.06 wt pct carbon steel was systematically studied using a dilatometer for two different heating rates (1 and 10 K/s). A step quenching treatment has been designed to develop dual-phase structures having a similar martensite fraction for two different heating rates. An increase in heating rate seemed to refine the ferrite grain size, but it increased the size and spacing of the martensitic regions. As a result, the strength of the steel increased with heating rate; however, the formability was affected. It has been concluded that the distribution of C during the annealing treatment of cold-rolled steel determines the size, distribution, and morphology of martensite, which ultimately influences the mechanical properties. Experimental detection of carbon distribution in austenite is difficult during annealing of the cold-rolled steel as the phase transformation occurs at a high temperature and C is an interstitial solute, which diffuses fast at that temperature. Therefore, a cellular automata (CA)-based phase transformation model is proposed in the present study for the prediction of C distribution in austenite during annealing of steel as the function of C content and heating rate. The CA model predicts that the carbon distribution in austenite becomes more inhomogeneous when the heating rate increases. In the CA model, the extent of carbon inhomogeneity is measured using a kernel averaging method for different orders of neighbors, which accounts for the different physical space during calculation. The obtained results reveal that the 10th order (covering 10- µm physical spaces around the cell of interest) is showing the maximum inhomogeneity of carbon and the same effect has been investigated and confirmed using auger electron spectroscopy (AES) for 0.06 wt pct carbon steel. Furthermore, the optimization of carbon homogeneity with respect to heating

  13. Microstructure Evolution and Mechanical Behavior of a Hot-Rolled High-Manganese Dual-Phase Transformation-Induced Plasticity/Twinning-Induced Plasticity Steel

    Science.gov (United States)

    Fu, Liming; Shan, Mokun; Zhang, Daoda; Wang, Huanrong; Wang, Wei; Shan, Aidang

    2017-05-01

    The microstructures and deformation behavior were studied in a high-temperature annealed high-manganese dual-phase (28 vol pct δ-ferrite and 72 vol pct γ-austenite) transformation-induced plasticity/twinning-induced plasticity (TRIP/TWIP) steel. The results showed that the steel exhibits a special Lüders-like yielding phenomenon at room temperature (RT) and 348 K (75 °C), while it shows continuous yielding at 423 K, 573 K and 673 K (150 °C, 300 °C and 400 °C) deformation. A significant TRIP effect takes place during Lüders-like deformation at RT and 348 K (75 °C) temperatures. Semiquantitative analysis of the TRIP effect on the Lüders-like yield phenomenon proves that a softening effect of the strain energy consumption of strain-induced transformation is mainly responsible for this Lüders-like phenomenon. The TWIP mechanism dominates the 423 K (150 °C) deformation process, while the dislocation glide controls the plasticity at 573 K (300 °C) deformation. The delta-ferrite, as a hard phase in annealed dual-phase steel, greatly affects the mechanical stability of austenite due to the heterogeneous strain distribution between the two phases during deformation. A delta-ferrite-aided TRIP effect, i.e., martensite transformation induced by localized strain concentration of the hard delta-ferrite, is proposed to explain this kind of Lüders-like phenomenon. Moreover, the tensile curve at RT exhibits an upward curved behavior in the middle deformation stage, which is principally attributed to the deformation twinning of austenite retained after Lüders-like deformation. The combination of the TRIP effect during Lüders-like deformation and the subsequent TWIP effect greatly enhances the ductility in this annealed high-manganese dual-phase TRIP/TWIP steel.

  14. Microstructure Evolution and Mechanical Behavior of a Hot-Rolled High-Manganese Dual-Phase Transformation-Induced Plasticity/Twinning-Induced Plasticity Steel

    Science.gov (United States)

    Fu, Liming; Shan, Mokun; Zhang, Daoda; Wang, Huanrong; Wang, Wei; Shan, Aidang

    2017-02-01

    The microstructures and deformation behavior were studied in a high-temperature annealed high-manganese dual-phase (28 vol pct δ-ferrite and 72 vol pct γ-austenite) transformation-induced plasticity/twinning-induced plasticity (TRIP/TWIP) steel. The results showed that the steel exhibits a special Lüders-like yielding phenomenon at room temperature (RT) and 348 K (75 °C), while it shows continuous yielding at 423 K, 573 K and 673 K (150 °C, 300 °C and 400 °C) deformation. A significant TRIP effect takes place during Lüders-like deformation at RT and 348 K (75 °C) temperatures. Semiquantitative analysis of the TRIP effect on the Lüders-like yield phenomenon proves that a softening effect of the strain energy consumption of strain-induced transformation is mainly responsible for this Lüders-like phenomenon. The TWIP mechanism dominates the 423 K (150 °C) deformation process, while the dislocation glide controls the plasticity at 573 K (300 °C) deformation. The delta-ferrite, as a hard phase in annealed dual-phase steel, greatly affects the mechanical stability of austenite due to the heterogeneous strain distribution between the two phases during deformation. A delta-ferrite-aided TRIP effect, i.e., martensite transformation induced by localized strain concentration of the hard delta-ferrite, is proposed to explain this kind of Lüders-like phenomenon. Moreover, the tensile curve at RT exhibits an upward curved behavior in the middle deformation stage, which is principally attributed to the deformation twinning of austenite retained after Lüders-like deformation. The combination of the TRIP effect during Lüders-like deformation and the subsequent TWIP effect greatly enhances the ductility in this annealed high-manganese dual-phase TRIP/TWIP steel.

  15. Microstructure, Tensile Properties and Work Hardening Behavior of GTA-Welded Dual-Phase Steels

    Science.gov (United States)

    Ashrafi, H.; Shamanian, M.; Emadi, R.; Saeidi, N.

    2017-03-01

    In the present study, microstructure, tensile properties and work hardening behavior of a DP700 steel after gas tungsten arc welding were investigated. Formation of bainite in the fusion zone resulted in a hardness increase compared to that for the base metal (BM), whereas tempering of the pre-existing martensite in the subcritical heat-affected zone (HAZ) led to softening. The GTA-welded joint exhibited a continuous yielding behavior and a yield strength close to that for the BM, while its ultimate tensile strength and total elongation were lower than those for the BM owing to the formation of soft zone in the HAZ. A joint efficiency of about 81% was obtained for the GTA-welded joint, and it failed in the softened HAZ. Analysis of work hardening based on the Kocks-Mecking approach showed one stage of hardening behavior corresponding to the stage III for both the DP700 BM and welded sample. It was also revealed that the DP700 BM has larger values of work hardening exponent and magnitude of work hardening compared with the welded sample. Analysis of fractured surfaces showed that the dominant fracture mode for both the DP700 BM and welded joint was ductile.

  16. Formation of CaO·TiO2-MgO·Al2O3 dual phase inclusion in Ti stabilized stainless steel

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The formation of CaO.TiO2-MgO.Al2O3 dual phase inclusion in 321 stainless steel was investigated in the laboratory. The result indicated that the condition for the formation of CaO.TiO2-MgO.Al2O3 in 321 steel is [Ca]>0.001wt%, [Ti]>0.1wt%, and[Al]>0.01wt%. The mechanism is the following: Al2O3 inclusion turns into CaO-Al2O3 after Ca-Si wire is fed into the molten steel;[Mg] is then obtained by reducing MgO in slag or crucible wall by [Al] and [Ti]; finally CaO-Al2O3 inclusion is changed into CaO.TiO2-MgO-Al2O3 by the reaction with [Mg], [Ti], and [O] in the molten steel simultaneously.

  17. Microstructure and Mechanical Properties of V-Nb Microalloyed Ultrafine-Grained Dual-Phase Steels Processed Through Severe Cold Rolling and Intercritical Annealing

    Science.gov (United States)

    Papa Rao, M.; Subramanya Sarma, V.; Sankaran, S.

    2017-03-01

    Ultrafine-grained (UFG) dual-phase (DP) steel was produced by severe cold rolling (true strain of 2.4) and intercritical annealing of a low carbon V-Nb microalloyed steel in a temperature range of 1003 K to 1033 K (730 °C to 760 °C) for 2 minutes, and water quenching. The microstructure of UFG DP steels consisted of polygonal ferrite matrix with homogeneously distributed martensite islands (both of size produced through intercritical annealing at 1013 K (740 °C) has good combination of strength (1295 MPa) and ductility (uniform elongation, 13 pct). The nanoscale V- and Nb-based carbides/carbonitrides and spheroidized cementite particles have played a crucial role in achieving UFG DP microstructure and in improving the strength and work hardening. Analysis of work hardening behavior of the UFG DP steels through modified Crussard-Jaoul analysis showed a continuously varying work hardening rate response which could be approximated by 2 or 3 linear regimes. The transmission electron microscopy analysis on post tensile-tested samples indicated that these regimes are possibly related to the work hardening of ferrite, lath, and twin martensite, respectively.

  18. Dual phase evolution

    CERN Document Server

    Green, David G; Abbass, Hussein A

    2014-01-01

    This book explains how dual phase evolution operates in all these settings and provides a detailed treatment of the subject. The authors discuss the theoretical foundations for the theory, how it relates to other phase transition phenomena and its advantages in evolutionary computation and complex adaptive systems. The book provides methods and techniques to use this concept for problem solving. Dual phase evolution concerns systems that evolve via repeated phase shifts in the connectivity of their elements. It occurs in vast range of settings, including natural systems (species evolution, landscape ecology, geomorphology), socio-economic systems (social networks) and in artificial systems (annealing, evolutionary computing).

  19. 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

  20. Evaluation of essential work of fracture in a dual phase high strength steel sheet; Evaluacion del trabajo esencial de fractura en chapa de un acero de alta resistencia de fase dual

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, D.; Perez, L. I.; Lara, A.; Casellas, D.; Prado, J. M.

    2013-03-01

    Fracture toughness of advanced high strength steels (AHSS), can be used to optimize crash behavior of structural components. However it cannot be readily measured in metal sheet because of the sheet thickness. In this work, the Essential Work of Fracture (EWF) methodology is proposed to evaluate the fracture toughness of metal sheets. It has been successfully applied in polymers films and some metal sheets. However, their information about the applicability of this methodology to AHSS is relatively scarce. In the present work the fracture toughness of a Dual Phase (strength of 800 MPa) and drawing steel sheets has been measured by means of the EWF. The results show that the test requirements are met and also show the clear influence of notch radii on the measured values, specially for the AHSS grade. Thus, the EWF is postulated as a methodology to evaluate the fracture toughness in AHSS sheets. (Author) 18 refs.

  1. Experimental Development of Dual Phase Steel Laser-arc Hybrid Welding and its Comparison to Laser and Gas Metal Arc Welding

    Directory of Open Access Journals (Sweden)

    Wagner Duarte Antunes

    Full Text Available Abstract Dual phase DP600 steels have been used in many automobile structures and laser welding has been the standard method for the joining of different sections. This work proposed a comparison between laser welding with arc welding (GMAW and with hybrid laser-arc welding in order to access the microstructures and the mechanical behavior. The laser and hybrid welds are competitive in terms of microstructure and mechanical behavior, presenting both acceptable and tough welds. The maximum ductility of the laser and hybrid welds are very similar, around 14%, and near to the values observed in the base material. The GMAW presents low ductility due to the softening caused by tampering of the martensite, and thus is unacceptable as the welding procedure.

  2. An Evaluation of Global and Local Tensile Properties of Friction-Stir Welded DP980 Dual-Phase Steel Joints Using a Digital Image Correlation Method

    Directory of Open Access Journals (Sweden)

    Hyoungwook Lee

    2015-12-01

    Full Text Available The effect of the microstructure heterogeneity on the tensile plastic deformation characteristic of friction-stir-welded (FSW dual-phase (DP steel was investigated for the potential applications on the lightweight design of vehicles. Friction-stir-welded specimens with a butt joint configuration were prepared, and quasi-static tensile tests were conducted, to evaluate the tensile properties of DP980 dual-phase steels. The friction-stir welding led to the formation of martensite and a significant hardness rise in the stir zone (SZ, but the presence of a soft zone in the heat-affected zone (HAZ was caused by tempering of the pre-existing martensite. Owing to the appearance of severe soft zone, DP980 FSW joint showed almost 93% joint efficiency with the view-point of ultimate tensile strength and relatively low ductility than the base metal (BM. The local tensile deformation characteristic of the FSW joints was also examined using the digital image correlation (DIC methodology by mapping the global and local strain distribution, and was subsequently analyzed by mechanics calculation. It is found that the tensile deformation of the FSW joints is highly heterogeneous, leading to a significant decrease in global ductility. The HAZ of the joints is the weakest region where the strain localizes early, and this localization extends until fracture with a strain near 30%, while the strain in the SZ and BM is only 1% and 4%, respectively. Local constitutive properties in different heterogeneous regions through the friction-stir-welded joint was also briefly evaluated by assuming iso-stress conditions. The local stress-strain curves of individual weld zones provide a clear indication of the heterogeneity of the local mechanical properties.

  3. Modeling of the Recrystallization and Austenite Formation Overlapping in Cold-Rolled Dual-Phase Steels During Intercritical Treatments

    Science.gov (United States)

    Ollat, M.; Massardier, V.; Fabregue, D.; Buscarlet, E.; Keovilay, F.; Perez, M.

    2017-07-01

    Austenite formation kinetics of a DP1000 steel was investigated from a ferrite-pearlite microstructure (either fully recrystallized or cold-rolled) during typical industrial annealing cycles by means of dilatometry and optical microscopy after interrupted heat treatments. A marked acceleration of the kinetics was found when deformed ferrite grains were present in the microstructure just before austenite formation. After having described the austenite formation kinetics without recrystallization and the recrystallization kinetics of the steel without austenite formation by simple JMAK laws, a mixture law was used to analyze the kinetics of the cold-rolled steel for which austenite formation and recrystallization may occur simultaneously. In the case where the interaction between these two phenomena is strong, three main points were highlighted: (i) the heating rate greatly influences the austenite formation kinetics, as it affects the degree of recrystallization at the austenite start temperature; (ii) recrystallization inhibition above a critical austenite fraction accelerates the austenite formation kinetics; (iii) the austenite fractions obtained after a 1 hour holding deviate from the local equilibrium fractions given by Thermo-Calc, contrary to the case of the recrystallized steel. This latter result could be due to the fact that the dislocations of the deformed ferrite matrix could promote the diffusion of the alloying elements of the steel and accelerate austenite formation.

  4. Position-dependent shear-induced austenite– martensite transformation in double-notched TRIP and dual-phase steel samples

    NARCIS (Netherlands)

    Blondé, R.J.P.; Jimenez-Melero, E.; Anusuya Ponnusami, S.; Zhao, L.; Schell, N.; Brück, E.H.; Van der Zwaag, S.; Van Dijk, N.H.

    2014-01-01

    While earlier studies on transformation-induced-plasticity (TRIP) steels focused on the determination of the austenite-to-martensite decomposition in uniform deformation or thermal fields, the current research focuses on the determination of the local retained austenite-to-martensite transformation

  5. Position-dependent shear-induced austenite– martensite transformation in double-notched TRIP and dual-phase steel samples

    NARCIS (Netherlands)

    Blondé, R.J.P.; Jimenez-Melero, E.; Anusuya Ponnusami, S.; Zhao, L.; Schell, N.; Brück, E.H.; Van der Zwaag, S.; Van Dijk, N.H.

    2014-01-01

    While earlier studies on transformation-induced-plasticity (TRIP) steels focused on the determination of the austenite-to-martensite decomposition in uniform deformation or thermal fields, the current research focuses on the determination of the local retained austenite-to-martensite transformation

  6. Influence of rapid heating process on the microstructure and tensile properties of high-strength ferrite-martensite dual-phase steel

    Institute of Scientific and Technical Information of China (English)

    Pei Li; Jun Li; Qing-ge Meng; Wen-bin Hu; Chun-fu Kuang

    2015-01-01

    Three low-carbon dual-phase (DP) steels with almost constant martensite contents of 20vol%were produced by intercritical an-nealing at different heating rates and soaking temperatures. Microstructures prepared at low temperature (1043 K, FH1) with fast-heating (300 K/s) show banded ferrite/martensite structure, whereas those soaked at high temperature (1103 K, FH2) with fast heating reveal blocky martensite uniformly distributed in the fine-grained ferrite matrix. Their mechanical properties were tested under tensile conditions and compared to a slow-heated (5 K/s) reference material (SH0). The tensile tests indicate that for a given martensite volume fraction, the yield strength and total elongation values are noticeably affected by the refinement of ferrite grains and the martensite morphology. Metallographic observations reveal the formation of microvoids at the ferrite/martensite interface in the SH0 and FH2 samples, whereas microvoids nucleate via the fracture of banded martensite particles in the FH1 specimen. In addition, analyses of the work-hardening behaviors of the DP micro-structures using the differential Crussard–Jaoul technique demonstrate two stages of work hardening for all samples.

  7. Processing of Bimodal Grain-Sized Ultrafine-Grained Dual Phase Microalloyed V-Nb Steel with 1370 MPa Strength and 16 pct Uniform Elongation Through Warm Rolling and Intercritical Annealing

    Science.gov (United States)

    Papa Rao, M.; Subramanya Sarma, V.; Sankaran, S.

    2014-11-01

    Ultrafine-grained dual phase microalloyed V-Nb steel with ultimate tensile strength of 1371 MPa and uniform elongation of 16 pct characterized by bimodal ferrite grain structure was obtained through warm rolling and subsequent intercritical annealing. The bimodal ferrite grain structure with uniform dispersion of Nb/V carbides and strong γ-fiber texture promoted high strain hardening rate and high uniform elongation and high strength is attributed to ultrafine-grained ferrite and martensite.

  8. Laser assisted conical spin forming of dual phase automotive steel. Experimental demonstration of work hardening reduction and forming limit extension

    Science.gov (United States)

    Romero, P.; Otero, N.; Cabrera, J. M.; Masagué, D.

    Laser Assisted Spin Forming is investigated for improving the poor formability of Advanced High Strength Steel DP-800 and Aeronautic Grade Titanium alloy, with minor or no change in microstructure, final properties improvements and no damage to coating, thanks to controlled energy input and fast thermal cycles. IR imaging and force-torque monitoring are used to characterise the forming process. Residual stress measurement, microstructure, microhardness and EBSD are used to study the formed parts under the combined action of laser and mechanical force. A micromechanism of laser assisted spinning is proposed, as well as advantages and limitations of the technique.

  9. CSP流程生产经济型热轧双相钢的工艺与组织性能%Technology and Microstructure-Mechanical Properties of Economical Hot Rolled Dual Phase Steel By CSP Process

    Institute of Scientific and Technical Information of China (English)

    韩斌; 谭文; 汪水泽; 张超; 蔡晓辉

    2011-01-01

    为了在CSP产线上开发新一代经济型热轧双相钢,并确定生产的最佳成分和工艺,介绍了在武钢CSP生产线进行580MPa级热轧双相钢的工业化生产试制情况。分别采用C-Mn-Si系和C-Mn-Si-Cr系钢为原料,通过控制轧制和基于超强冷却设备的控制冷却工艺,成功开发出抗拉强度580MPa级热轧双相钢。通过比较分析2种成分钢的力学性能和微观组织,结果表明:经济型的C-Mn-Si系钢相对于C-Mn-Si-Cr系钢具有屈服强度低、屈强比小、伸长率大的特点,虽然马氏体量相对较少,但具有马氏体呈岛状更加均匀分布在铁素体晶界上等典型双相钢的特征,同时提出了生产过程中控制铁素体析出量和促进马氏体形成的具体措施。%In order to develop new generation economical DP steel and obtain the optimum composition and processing parameters in CSP line,the pilot production of 580 MPa hot-rolled dual phase strip at WISCO CSP Plant was introduced.Two series of dual phase steel,such as plain C-Mn-Si and C-Mn-Si-Cr steel,were produced successfully by controlled rolling and controlled cooling with ultra fast cooling capacity.The tensile strength of both series of DP steel achieves 580 MPa.Comparison of mechanical properties and microstructure between two steels,the results show that the cost of C-Si-Mn steel is lower than C-Si-Mn-Cr steel,C-Si-Mn steel has lower yield stress,lower yield strength/tensile strength ratio and higher elongation.Although obtained martensite fraction in C-Si-Mn steel was lower,the island martensite distributed among the ferrite grain boundaries was more uniform.The specific measures of controlling ferrite formation and promoting martensite transformation were put forward.

  10. MICROSTRUCTURE AND PROPERTIES OF 600 MPa GRADE COLD ROLLED DUAL-PHASE STEEL%600MPa级含钒冷轧双相钢的组织性能研究

    Institute of Scientific and Technical Information of China (English)

    罗娟娟; 史文; 黄群飞; 李麟

    2011-01-01

    Cold rolled low carbon Si-Mn containing V dual phase steels of 600 Mpa grade were exploited in laboratory. The microstructure and property of tested steels after continuous annealing were measured. The results showed that the tested steels which had good mechanical properties could be obtained by annealing at 800 ℃, over-ageing at 300 ℃. After heat treatment, the yield strength was 358 Mpa, the tensile strength was 637 Mpa, the elongation and BH value reached 23.7% and 55 Mpa respectively. V element had two kinds of existent states, one was precipitate in ferrite, and another one was solute in ferrite, the main roles of vanadium in dual-phase steel was precipitation strength and refining grain size.%在实验室试制600 MPa级低碳Si-Mn含钒冷轧双相钢,研究了连续退火后试验钢的组织和力学性能.结果表明:经800℃保温,300℃过时效处理,可以获得综合力学性能优良的冷轧双相钢,其屈服强度为358 MPa,抗拉强度为637 MPa,伸长率达到了23.7%,BH值为55 MPa;钢中V主要以析出物和在铁素体中以固溶态两种状态存在,主要起到析出强化和细化晶粒的作用.

  11. Dual Phase Cosmic Rays

    CERN Document Server

    Shurtleff, Richard

    2008-01-01

    A calculation based on flat spacetime symmetries shows how there can be two quantum phases. For one, extreme phase change determines a conventional classical trajectory and four-momentum, i.e. mass times four-velocity. The other phase occurs in an effective particle state, with the effective energy and momentum being the rate of change of the phase with respect to time and distance. A cosmic ray proton moves along a classical trajectory, but exists in an effective particle state with an effective energy that depends on the local gravitational potential. Assumptions are made so that a cosmic ray proton in an ultra-high energy state detected near the Earth was in a much less energetic state in interstellar space. A 300 EeV proton incident on the Earth was a 2 PeV proton in interstellar space. The model predicts such protons are in states with even more energy near the Sun than when near the Earth.

  12. Determinação dos campos de soldabilidade para o aço Dual-Phase 600 em equipamentos de soldagem a ponto AC e MFDC Determination of weldability fields for Dual-Phase 600 steel in AC and MFDC RSW

    Directory of Open Access Journals (Sweden)

    Marco Antonio Wolff

    2010-09-01

    welding equipments: AC (alternating current and MFDC (medium-frequency direct current. The first technology (AC equipment is the traditional one and has been successfully applied to accomplish weldments in low-carbon steel sheets, with relatively low cost. On the other hand, the new technology (MFDC equipment has been propagated by the manufactures as an evolution of the resistance spot welding, where higher productivity, lower energy consumption, better parameters controlling and lower thermal-mechanical stress. Besides these claimed qualities, from the construction point of view, the MFDC equipment demands smaller transformers, since its efficiency is proportional to the input frequency, i.e., the AC equipment uses the 60-Hz (in the Brazilian case from the power lines, whereas the MFDC ones goes for 1000 Hz, increasing its efficiency and reducing its size. Despite these commercial claims of the MFDC-equipment manufacturers, few scientific results have been published with a thorough methodology of comparison, especially for the recently introduced dual-phase steels. Therefore, this work is aimed to provide the comparison between MFDC and AC resistance spot welding equipment by using an appropriated methodology based on the equivalent size of the obtained spot. It is expected the results lead to further discussion between the use of these two equipments.

  13. Mod\\'elisation multidomaine du comportement magn\\'eto-m\\'ecanique des aciers dual-phases

    CERN Document Server

    Mballa, Frederick Mballa; Lazreg, Said; Meilland, Philip

    2011-01-01

    The microstructure and mechanical behavior of dual-phase steels are highly sensitive to the variation of the process (heat treatments). Online control by magnetic method is relevant. A measurement under applied stress must be considered. The dual-phase is a two-phase medium (ferrite / martensite). Each phase can be considered as a sphere embedded in a homogeneous equivalent medium. The model used for each phase is based on a magneto-mechanical coupled model. This is an explicit single crystalline model representative of the behavior of the corresponding phase. Localization rules allow the simulation of the two-phases medium. Experiments and modeling are compared.

  14. 控冷工艺对热轧双相钢盘条组织和性能的影响%Effect of Controlling Cooling Process on Microstructure and Properties of Dual Phase Steel Wire Rods

    Institute of Scientific and Technical Information of China (English)

    徐向俊; 孔俊其

    2012-01-01

    通过840℃精轧后空冷到760℃然后淬水(工艺1)和850℃精轧后在保温罩中缓冷到760℃然后风冷(工艺2)两种工艺轧制ER70s-6钢盘条,并分析了其盘条的组织和性能.结果表明,工艺1生产的盘条横截面表层和内部组织不均匀,内部含20.7%成条带状分布的马氏体,其抗拉强度、屈服强度和伸长率分别为725、382 MPa和16.5%:工艺2生产的盘条组织较均匀,含11.5%马氏体,其抗拉强度、屈服强度和伸长率分别为608、338 MPa和31.3%.双相钢中马氏体含量高对强度有利,但其成条带状分布对塑性不利.%ER70s-6 steel wire rods rolled at finishing rolling temperature of 840 ℃ and cooled to 760℃ in air then quenched in water (process 1) and rolled at finishing rolling temperature of 850 ℃, cooled to 760 ℃ in heat insulation mantle and then cooled in flow air (process 2) were produced, and their microstructures and the mechanical properties were analyzed. The results show that the wire rod produced in process 1 has different microstructures between internal and external parts of the rod cross section. In internal part the martensite distributed in banded form is 20.7% in volume fraction. The wire rod produced in process 2 has uniform microstructure with 11.5% martensite in volume fraction. The wire rod produced in process 1 has yield strength level of 382MPa, ultimate tensile strength level of 725 MPa and plastic elongation of 16.5 %, respectively. The wire rod produced in process 2 has yield strength level of 338MPa, ultimate tensile strength level of 608 MPa and plastic elongation of 31.3%, respectively. For dual phase steel high content of martensite is beneficial for strength, but the bended distribution of martensite is bad for the ductility.

  15. Effect of intercritical temperature and cold-deformation on the kinetics of austenite formation during the intercritical annealing of dual-phase steels

    Energy Technology Data Exchange (ETDEWEB)

    El-Sesy, I.A.; Hussein, A.H.A. (Cairo Univ., Gizeh (Egypt). Dept. of Mining, Petroleum and Metallurgical Engineering); Klaar, H.J. (Technische Hochschule Aachen (Germany, F.R.). Gemeinschaftslaboratorium fuer Elektronenmikroskopie)

    1990-01-01

    The objective of this investigation was to study the effect of the intercritical temperature and percentage of cold-deformation on the kinetics of austenite formation during the intercritical annealing in the alpha + gamma ({alpha} + {gamma}) phase field of the iron-carbon phase diagram. This investigation was carried out on an Fe-0.11 C-1.58 Mn-0.4 Si ferritic-pearlitic alloy with different structures of 0% (hot-rolled), 25% and 50% cold-deformation. The intercritical annealing temperatures were 735, 750deg C and the intercritical annealing time ranged from 15 to 1815 s. It has been observed that recrystallization of the deformed ferrite was completed before any austenite formation. Surprisingly, it was noted that the recrystallized ferrite grain size was independent of percentage cold-deformation. Furthermore, it was expected that cold-deformation accelerates the kinetics of austenite formation. Nevertheless, the amounts of austenite formed from pearlite dissolution were mostly equal, irrespective of the starting condition. As has been previously reported, increasing the intercritical annealing temperature was found to increase the amount of austenite. (orig.).

  16. Phase Transformation in Cast Superaustenitic Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Lee Phillips, Nathaniel Steven [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    Superaustenitic stainless steels constitute a group of Fe-based alloys that are compositionally balanced to have a purely austenitic matrix and exhibit favorable pitting and crevice corrosion resistant properties and mechanical strength. However, intermetallic precipitates such as sigma and Laves can form during casting or exposure to high-temperature processing, which degrade the corrosion and mechanical properties of the material. The goal of this study was to accurately characterize the solid-solid phase transformations seen in cast superaustenitic stainless steels. Heat treatments were performed to understand the time and temperature ranges for intermetallic phase formations in alloys CN3MN and CK3MCuN. Microstructures were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy and wavelength dispersive spectroscopy (EDS, WDS). The equilibrium microstructures, composed primarily of sigma and Laves within purely austenitic matrices, showed slow transformation kinetics. Factors that determine the extent of transformation, including diffusion, nucleation, and growth, are discussed.

  17. Behaviour of Z phase in 9–12%Cr steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Hald, John

    2006-01-01

    –12%), Z phase precipitates much faster than in 9%Cr steels. Precipitation of Z phase is associated with dissolution of MX carbonitrides, and causes a breakdown in long term creep strength in 9–12%Cr steels. High Cr steels show creep instabilities accompanied with Z phase precipitation, whereas low Cr......–1250uC solution temperature of the unmodified CrNbN Z phase. Above the solution temperature the modified Z phase is replaced by MX particles....

  18. Phases in austenitic stainless steels: Faze v avstenitnih nerjavnih jeklih:

    OpenAIRE

    JANOVEC, Jozef; Jenko, Monika; Medved, Jože; Šuštaršič, Borivoj

    2003-01-01

    The study represents a phase characterisation of austenitic stainless steels. A table presents the basic literature data on the phases to be found in austenitic steels. For the as-cast ASTM A351 steel, a thermodynamic prediction and a metallographic identification of phases is also presented. The thermodynamic calculations performed using ThermoCalc revealed austenite, ferrite, Msub(23)Csub(6), delta, and Laves as the equilibrium phases at temperatures below 866 K (953 compositumC). All the p...

  19. Phase Transformations in Cast Duplex Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yoon-Jun [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    Duplex stainless steels (DSS) constitute both ferrite and austenite as a matrix. Such a microstructure confers a high corrosion resistance with favorable mechanical properties. However, intermetallic phases such as σ and χ can also form during casting or high-temperature processing and can degrade the properties of the DSS. This research was initiated to develop time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams of two types of cast duplex stainless steels, CD3MN (Fe-22Cr-5Ni-Mo-N) and CD3MWCuN (Fe-25Cr-7Ni-Mo-W-Cu-N), in order to understand the time and temperature ranges for intermetallic phase formation. The alloys were heat treated isothermally or under controlled cooling conditions and then characterized using conventional metallographic methods that included tint etching, and also using electron microscopy (SEM, TEM) and wavelength dispersive spectroscopy (WDS). The kinetics of intermetallic-phase (σ + χ) formation were analyzed using the Johnson-Mehl-Avrami (MA) equation in the case of isothermal transformations and a modified form of this equation in the case of continuous cooling transformations. The rate of intermetallic-phase formation was found to be much faster in CD3MWCuN than CD3MN due mainly to differences in the major alloying contents such as Cr, Ni and Mo. To examine in more detail the effects of these elements of the phase stabilities; a series of eight steel castings was designed with the Cr, Ni and Mo contents systematically varied with respect to the nominal composition of CD3MN. The effects of varying the contents of alloying additions on the formation of intermetallic phases were also studied computationally using the commercial thermodynamic software package, Thermo-Calc. In general, σ was stabilized with increasing Cr addition and χ by increasing Mo addition. However, a delicate balance among Ni and other minor elements such as N and Si also exists. Phase equilibria in DSS can be affected by

  20. Phase Transformations in Cast Duplex Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Yoon-Jun Kim

    2004-12-19

    Duplex stainless steels (DSS) constitute both ferrite and austenite as a matrix. Such a microstructure confers a high corrosion resistance with favorable mechanical properties. However, intermetallic phases such as {sigma} and {chi} can also form during casting or high-temperature processing and can degrade the properties of the DSS. This research was initiated to develop time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams of two types of cast duplex stainless steels, CD3MN (Fe-22Cr-5Ni-Mo-N) and CD3MWCuN (Fe-25Cr-7Ni-Mo-W-Cu-N), in order to understand the time and temperature ranges for intermetallic phase formation. The alloys were heat treated isothermally or under controlled cooling conditions and then characterized using conventional metallographic methods that included tint etching, and also using electron microscopy (SEM, TEM) and wavelength dispersive spectroscopy (WDS). The kinetics of intermetallic-phase ({sigma} + {chi}) formation were analyzed using the Johnson-Mehl-Avrami (MA) equation in the case of isothermal transformations and a modified form of this equation in the case of continuous cooling transformations. The rate of intermetallic-phase formation was found to be much faster in CD3MWCuN than CD3MN due mainly to differences in the major alloying contents such as Cr, Ni and Mo. To examine in more detail the effects of these elements of the phase stabilities; a series of eight steel castings was designed with the Cr, Ni and Mo contents systematically varied with respect to the nominal composition of CD3MN. The effects of varying the contents of alloying additions on the formation of intermetallic phases were also studied computationally using the commercial thermodynamic software package, Thermo-Calc. In general, {sigma} was stabilized with increasing Cr addition and {chi} by increasing Mo addition. However, a delicate balance among Ni and other minor elements such as N and Si also exists. Phase equilibria in

  1. A new nanoscale metastable iron phase in carbon steels

    OpenAIRE

    Tianwei Liu; Danxia Zhang; Qing Liu; Yanjun Zheng; Yanjing Su; Xinqing Zhao; Jiang Yin; Minghui Song; Dehai Ping

    2015-01-01

    Metastable ω phase is common in body-centred cubic (bcc) metals and alloys, including high-alloying steels. Recent theoretical calculations also suggest that the ω structure may act as an intermediate phase for face-centred cubic (fcc)-to-bcc transformation. Thus far, the role of the ω phase played in fcc-bcc martensitic transformation in carbon steels has not been reported. In previous investigations on martensitic carbon steels, extra electron diffraction spots were frequently observed by t...

  2. Recent Development of Air-Cooled Bainitic Steels Containing Manganese

    Institute of Scientific and Technical Information of China (English)

    FANG Hong-sheng; YANG Fu-bao; BAI Bing-zhe; YANG Zhi-gang; YIN Jiang

    2005-01-01

    The superiorities of air-cooled bainitic steels were described.A series of air-cooled bainitic steels containing manganese were developed and presented,which include low carbon granular bainitic steels,low carbon grain-boundary allotriomorphic ferrite/granular bainite dual phase steels,medium and medium high carbon bainite/martensite dual phase steels and casting bainitic steels.The development of ultra-low carbon bainitic steels in China was also introduced.

  3. Thermodynamic Analysis on Precipitated Phases in Low Activation Steel

    OpenAIRE

    PANG Qi-hang; TANG Di; ZHAO Zheng-zhi; WU Hui-bin; Li, Shuo

    2016-01-01

    A type of low-carbon reduced activation ferritic/martensitic (RAFM) steel is designed.The microstructure and mechanical properties of tested steels prepared by different technologies were investigated by means of scanning electron microscope, transmission electron microscope and tensile test. The chemical composition of precipitations of tested steels are inspected by energy dispersive spectroscopy (EDS), meanwhile the law of precipitation phase of low carbon low activation FM steel was studi...

  4. Towards a phase field model of the microstructural evolution of duplex steel with experimental verification

    DEFF Research Database (Denmark)

    Poulsen, Stefan Othmar; Voorhees, P.W.; Lauridsen, Erik Mejdal

    2012-01-01

    A phase field model to study the microstructural evolution of a polycrystalline dual-phase material with conserved phase fraction has been implemented, and 2D simulations have been performed. For 2D simulations, the model predicts the cubic growth well-known for diffusion-controlled systems. Some...... interphase boundaries are found to show a persistent non-constant curvature, which seems to be a feature of multi-phase materials. Finally, it is briefly outlined how this model is to be applied to investigate microstructural evolution in duplex steel. © (2012) Trans Tech Publications, Switzerland....

  5. Behaviour of Z phase in 9–12%Cr steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Hald, John

    2006-01-01

    –12%), Z phase precipitates much faster than in 9%Cr steels. Precipitation of Z phase is associated with dissolution of MX carbonitrides, and causes a breakdown in long term creep strength in 9–12%Cr steels. High Cr steels show creep instabilities accompanied with Z phase precipitation, whereas low Cr...... steels show good long term creep stability. A niobium free CrVN variant of the modified Z phase was observed for the first time during the course of this work. The solution temperature of the Cr(V,Nb)N and CrVN modified Z phases was found to be close to 800uC for 11–12%Cr steels, much lower than the 1200......The literature on the behaviour of modified Z phase Cr(V,Nb)N in creep resistant martensitic 9–12%Cr steels is briefly reviewed. Ten different 9–12%Cr steels were investigated after prolonged exposure at 600–660uC; the modified Z phase was found in all of them. In steels with high Cr content (11...

  6. Effects of Ferrite Grain Size on Dynamic Deformation Behavior of Ferrite-martensite Dual Phase Steel DP980%铁素体晶粒尺寸对铁素体——马氏体双相钢DP980动态变形行为影响

    Institute of Scientific and Technical Information of China (English)

    代启锋; 宋仁伯; 关小霞; 郭志飞

    2012-01-01

    为了研究铁素体晶粒尺寸对铁素体一马氏体冷轧双相钢DP980动态变形行为的影响,通过连续退火试验,得到两组马氏体体积分数相同、而铁素体晶粒尺寸不同的试样.选取应变速度为1×10-4 s-1和1×10-2s-1进行准静态拉伸试验:选取应变速度为500 s-1、1 000s-1和1 750 s-1在分离式霍普金森拉杆(Split Hopkinson tensile bar,SHTB)上进行动态拉伸试验.使用不考虑晶粒尺寸影响的Johnson-Cook(J-C)率相关模型和考虑晶粒尺寸影响的修正的Khan-Huang-Liang(KHL)率相关模型分析双相钢的动态变形行为,并引入可决系数R2来判定试验结果与模型的吻合关系.分析结果得出修正的KHL模型与试验结果吻合较好,其可决系数R2达到了0.998 7,表明修正的KHL模型可以很好地描述DP980材料在低应变速度和高应变速度下的变形行为,能够反映铁素体晶粒尺寸对DP980动态变形行为的影响.%Effects of ferrite grain size on quasi-static and dynamic deformation behavior of ferrite-martensite dual phase steel (DP980) are investigated. Two groups of experimental dual phase DP steels with the same martensite volume fraction and different ferrite grain size are obtained through performing the experiment with different austenitizing temperature. The quasi-static tensile experiment and the dynamic tensile experiment for the two groups of DP steels are carried out at strain rates ranging from 10~4 to 1 750 s~' at room temperature using universal testing machine CMT4105 and split Hopkinson tensile bar (SHTB), respectively. Then the true stress-effective plastic strain curves of DP980 steel for five strain rates have been obtained through the data processing. Johnson-Cook (J-C) model, which is not concerned with effects of grain size, and modified Khan, Huang and Liang (KHL) model, which is concerned with effects of grain size, are used to research dynamic deformation behavior of dual phase steel. And coefficient of

  7. Nanophase formation and its behavior of corrosion resistance in C+Ti dual implanted steel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    [1]Zhang Huixing,Zhang Xiaoji,Zhou Fengsheng et al.,High current metal-ion source for ion implantation,Rev.Sci.Instrum.,1990,61(1): 574.[2]Zhang Tonghe,Ji Chengzhou,Shen Jinghua et al.,Surface modification of steel by high-dose pulse-ion implantation of titanium,tungsten,molybdenum and carbon,Nucl.Instrum.Methods,1991,B59/60: 828.[3]Zhang Tonghe,Ji Chengzhou,Shen Jinghua et al.,The influence of Ti,N and Ti+N implantation on phase change,microstructure,growth of metallic compounds and correlated effects in hardness and wear resistance in H13 steel,Nucl.Instrum.Methods,1993,B72: 409-420.[4]Zhang Tonghe,Huang Huapeng,Ji Chengzhou et al.,The formation of metallic silicides of Ti,Y,Fe,Mo and W using metal vapor vacuum arc implantation,Surf.Coat.Technol.,1994,66: 355-360.[5]Zhang Tonghe,Ji Chengzhou,Shen Jinghua et al.,Formation of intermetallic compounds with a high flux pulse molybdenum ion beam in steel and aluminum,Surf.Coat.Technol.,1992,51:455-460.[6]Zhang Tonghe,Wang Xiaoyan,Liang Hong et al.,Behavior of MEVVA metal ion implantation for surface modification of materials,Surf.Coat.Technol.,1996,83: 280-283.[7]Zhang Tonghe,Wang Xiaoyan,Liang Hong et al.,Behavior of MEVVA metal ion implantation for surface modification of materials,Surf.Coat.Technol.,1996,83: 280-283.[8]Takakashi,K.,Waki,M.I.,Chemical and electrochemical properties of ion implanted metals,Surf.Coat.Technol.,1994,65:57-63.[9]Wolf,G K.,An historical perspective of ion bombardment research for corrosion studies,Surf.Coat.Technol.,1996,83: 1-9.[10]Zhang Tonghe,Wu Yuguang,Deng Zhiwei et al.,The corrosion behavior of nanometer embedded phase in Ti implanted H13 steel,Science in China,Ser.E,1999,42(6): 623-630.[11]Zhang Tonghe,Wu Yuguang,Yi Zhongzhen et al.,Nanophase formation and its behavior of corrosion resistance in C+Mo dual implanted steel,Science in China,Ser.E,2001,4(4): 383-388.[12]Zhang Tonghe,Wu Yuguang,Deng Zhiwei et al.Properties of corrosion

  8. Dual Phase Membrane for High Temperature CO2 Separation

    Energy Technology Data Exchange (ETDEWEB)

    Jerry Lin

    2007-06-30

    This project aimed at synthesis of a new inorganic dual-phase carbonate membrane for high temperature CO{sub 2} separation. Metal-carbonate dual-phase membranes were prepared by the direct infiltration method and the synthesis conditions were optimized. Permeation tests for CO{sub 2} and N{sub 2} from 450-750 C showed very low permeances of those two gases through the dual-phase membrane, which was expected due to the lack of ionization of those two particular gases. Permeance of the CO{sub 2} and O{sub 2} mixture was much higher, indicating that the gases do form an ionic species, CO{sub 3}{sup 2-}, enhancing transport through the membrane. However, at temperatures in excess of 650 C, the permeance of CO{sub 3}{sup 2-} decreased rapidly, while predictions showed that permeance should have continued to increase with temperature. XRD data obtained from used membrane indicated that lithium iron oxides formed on the support surface. This lithium iron oxide layer has a very low conductivity, which drastically reduces the flow of electrons to the CO{sub 2}/O{sub 2} gas mixture; thus limiting the formation of the ionic species required for transport through the membrane. These results indicated that the use of stainless steel supports in a high temperature oxidative environment can lead to decreased performance of the membranes. This revelation created the need for an oxidation resistant support, which could be gained by the use of a ceramic-type membrane. Work was extended to synthesize a new inorganic dual-phase carbonate membrane for high temperature CO{sub 2} separation. Helium permeance of the support before and after infiltration of molten carbonate are on the order of 10{sup -6} and 10{sup -10} moles/m{sup 2} {center_dot} Pa {center_dot} s respectively, indicating that the molten carbonate is able to sufficiently infiltrate the membrane. It was found that La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (LSCF) was a suitable candidate for the support

  9. Sigma phase formation kinetics in stainless steel laminate composites

    Energy Technology Data Exchange (ETDEWEB)

    Wenmen, D.W.; Olson, D.L.; Matlock, D.K. [Colorado School of Mines, Golden, CO (United States)] [and others

    1994-12-31

    Stainless steel laminate composites were made to simulate weld microstructures. The use of laminates with variations in chemical composition allows for one dimensional analysis of phase transformation associated with the more complex three-dimensional solidification experience of weld metal. Alternate layers of austenitic (304L and 316L) and ferritic (Ebrite) stainless steels allowed for the study of sigma phase formation at the austenite-ferrite interface in duplex stainless steel. Two austenitic stainless steels, 304L (18.5Cr-9.2Ni-0.3Mo) and 316L (16.2Cr-10.1Ni-2.6Mo), and one ferritic stainless steel, Ebrite (26.3Cr-0Ni-1.0Mo) were received in the form of sheet which was laboratory cold rolled to a final thickness of 0.25 mm (0.030 in.). Laminate composites were prepared by laboratory hot rolling a vacuum encapsulated compact of alternating layers of the ferrite steel with either 304L or 316L stainless steel sheets. Laminate composite specimens, which simulate duplex austenite-ferrite weld metal structure, were used to establish the kinetics of nucleation and growth of sigma phase. The factors affecting sigma phase formation were identified. The effects of time, temperature, and transport of chromium and nickel were evaluated and used to establish a model for sigma phase formation in the austenite-ferrite interfacial region. Information useful for designing stainless steel welding consumables to be used for high temperature service was determined.

  10. STEEL CORROSION AT 600°C IN SINGLE AND DUAL CONDITION IN OXYFUEL ATMOSPHERE

    Directory of Open Access Journals (Sweden)

    Daniel Massari de Souza Coelho

    2014-10-01

    Full Text Available Coal-fired power plants using the Oxyfuel process are being developed to produce electricity with zero CO2 emission. Steels used in this and other processes are often exposed to different atmospheres in each side of the material, especially in heat exchangers and solid oxide fuel cells. Some studies have shown that steels exposed to different hydrogen partial pressures in each side have a different corrosion behavior from steels exposed to a single atmosphere condition. In this investigation, two experimental steels were studied at 600°C and 1 atm in dual atmospheres containing water vapor in one side and flue gas in the other and they were compared to steels oxidized in single atmospheres. The gas composition used is similar to the ones found in Oxyfuel coal power plants, where there is a great concentration of CO2, and also H2O and SO2. Analyses were made using SEM and TEM.

  11. Thermal and phase transformations analysis in a PREMOMET® steel

    Directory of Open Access Journals (Sweden)

    M. Torres-López

    2017-01-01

    Full Text Available Thermal analysis in a PREMOMET® steel has been performed by differential scanning calorimetry (DSC and highresolution dilatometry. The phase transformation temperatures (Ac1, Ac3, Ms and Mf of this steel were obtained by the two methods at different heating rates showing good agreement between both techniques. The enthalpy of α-γ transformation for this steel was measured using the thermograms acquired by DSC and microstructure was analyzed by scanning electron microscope (SEM. The results showed that this steel retained a martensitic structure for all conditions.

  12. Cold-rolled complex-phase steels: AHSS material with remarkable properties

    Energy Technology Data Exchange (ETDEWEB)

    Hebesberger, T.; Pichler, A.; Walch, C.; Blaimschein, M. [voestalpine Stahl GmbH, Linz (Austria); Spiradek-Hahn, K. [ARC Seibersdorf Research GmbH (Austria)

    2005-07-01

    The reduction of the body-in-white weight, in combination with stiffness and crash safety improvements is of fundamental interest in the automotive industry. Therefore, several Advanced High Strength Steel (AHSS) grades have been developed in the last several years, whereby the main focus was laid on dual-phase (DP) and TRIP steels. Recently, a new high strength steel grade - complex-phase (CP) steels - is gaining more and more interest. In contrast to DP grades of similar strength level, CP grades have a significantly higher yield strength and thus a higher yield ratio. Although, CP grades reach lower elongation values in the tensile test, they show an excellent bendability and stretch-flangeability. Due to this remarkable balance between strength, bendability and stretch-flangeability, complex-phase steels are potential candidates for roll-formed parts and parts where sharp radii and/or a good formability of punched edges are required. Therefore, the microstructure, the processing, and the formability of CP grades are discussed in detail in this work. (orig.)

  13. Z-phase in 9-12% Cr steels

    Energy Technology Data Exchange (ETDEWEB)

    Danielsen, Hilmar; Hald, John [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Manufacturing Engineering and Management

    2004-04-01

    Precipitation of the complex nitride Z-phase Cr(Nb,V)N has recently been identified as a major cause for premature breakdown in creep strength of a number of new 9-12%Cr martensitic steels. These steels are primarily used in steam pipes and steam turbines of thermal power plants. Z-phase precipitation cancels out the beneficial effects of MX carbo-nitrides rich in V and Nb, which form the backbone of the creep strength of 9-12%Cr steels. Very little is known about the stability of Z-phase, and there are currently no means of predicting its occurrence. The development of a thermodynamic model based on the Thermo-Calc software could provide means to predict in which steels the Z-phase will appear. Ultimately this could form the basis for development of new high strength 9-12%Cr martensitic steels that would be immune to Z-phase precipitation. This could hopefully increase service parameters of future power plants and thus raise efficiency. A literature survey of the Z-phase was made in order to gather all available information for a thermodynamic model, mainly chemical composition and solution temperature of the Z-phase as a function of steel composition are of importance. The survey did not give a complete overview of the Z-phase, so heat treatment experiments and metallographic investigations were carried out to fill the identified gaps. As the model neared completion it became clear that it predicted the Z-phase to be stable in basically all 9-12%Cr steels, that contain its constituents. This also applied to steels like the X20CrMoV121 (12CrMoV), which has been in service for decades and has shown no signs of a breakdown in strength. Close inspection of this steel after very long service exposure showed the Z-phase to be present in a new version (CrVN), albeit in much smaller quantities compared with the newer steels. This effectively makes Z-phase precipitation a kinetic problem, and if its precipitation is sufficiently slow it will not affect the stability of a

  14. Clean Cast Steel Technology, Phase IV

    Energy Technology Data Exchange (ETDEWEB)

    Charles E. Bates

    2003-02-24

    The objective of the Clean Cast Steel Technology Program was to improve casting product quality by removing or minimizing oxide defects and to allow the production of higher integrity castings for high speed machining lines. Previous research has concentrated on macro-inclusions that break, chip, or crack machine tool cutters and drills and cause immediate shutdown of the machining lines. The overall goal of the project is to reduce the amount of surface macro-inclusions and improve the machinability of steel castings. Macro-inclusions and improve the machinability of steel castings. Macro-inclusions have been identified by industrial sponsors as a major barrier to improving the quality and marketability of steel castings.

  15. Steel Primer Chamber Assemblies for Dual Initiated Pyrovalves

    Science.gov (United States)

    Guemsey, Carl S.; Mizukami, Masashi; Zenz, Zac; Pender, Adam A.

    2009-01-01

    A solution was developed to mitigate the potential risk of ignition failures and burn-through in aluminum primer chamber assemblies on pyrovalves. This was accomplished by changing the assembly material from aluminum to steel, and reconfiguration of flame channels to provide more direct paths from initiators to boosters. With the geometric configuration of the channels changed, energy is more efficiently transferred from the initiators to the boosters. With the alloy change to steel, the initiator flame channels do not erode upon firing, eliminating the possibility of burn-through. Flight qualification tests have been successfully passed.

  16. Liquid Phase Sintering of Highly Alloyed Stainless Steel

    DEFF Research Database (Denmark)

    Mathiesen, Troels

    1996-01-01

    Liquid phase sintering of stainless steel is usually applied to improve corrosion resistance by obtaining a material without an open pore system. The dense structure normally also give a higher strength when compared to conventional sintered steel. Liquid phase sintrering based on addition...... of boride to AISI 316L type steels have previously been studied, but were found to be sensitive to intergranular corrosion due to formation of intermetallic phases rich in chromium and molybdenum. In order to improve this system further, new investigations have focused on the use of higher alloyed stainless...... steel as base material. The stainless base powders were added different amounts and types of boride and sintered in hydrogen at different temperatures and times in a laboratory furnace. During sintering the outlet gas was analyzed and subsequently related to the obtained microstructure. Thermodynamic...

  17. Tensile Mechanical Behaviour of Ultra-High Strength Cold Rolled Dual Phase Steel DP1000 at High Strain Rates%超高强冷轧双相钢DP1000高应变速率下的拉伸性能

    Institute of Scientific and Technical Information of China (English)

    代启锋; 宋仁伯; 蔡恒君; 于三川; 高喆

    2013-01-01

    使用CMT4105型电子万能试验机和霍普金森拉杆(SHTB)装置研究了超高强冷轧双相钢DP1000在室温下的准静态和动态拉伸力学性能.结果表明:应变速率范围在0.0001-2250 s-1,DP1000双相钢具有明显的应变速率敏感性,表现出较强的应变速率增强效应,强度随着应变速率的增加而增加;Johnson-Cook模型能够在一定程度上描述DP1000双相钢在高应变速率下变形行为,但由于应变速率敏感性在高应变速率下吻合程度较差;对Johnson-Cook模型的应变速率效应多项式进行二次化修正后,模型能很好地描述DP1000双相钢在高应变速率下的变形行为,平均可决系数从0.9434提高到0.9850.%Quasi-static and dynamic tensile mechanical behaviour of ultra-high strength cold rolled dual phase steel DP1000 at room temperature and wide strain rates (0.0001-2250 s1) with electronic universal testing machine CMT4105 and split Hopkinson tensile bar (SHTB) apparatus were investigated. The results show that DP1000 steel is a sensitive material to strain rate, and the strength increases with the increase of strain rate; Johnson-Cook model can represent, to some extent, deformational behaviour for DP1000 steel at high strain rates, but owing to strain rate sensitivity, the goodness of fit is poor at high strain rate. The polynomial of strain rate effect was modified based on Johnson-Cook model, and the modified dynamic constitutive model can make a satisfied prediction to the plastic flow stress of DP1000 steel at high strain rates, and the average coefficient of determination can be improved from 0.9434 to 0.9850.

  18. Z-phase in 9-12% Cr Steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar; Hald, John

    2004-01-01

    -phase to be stable in all of the new 9-12%Cr martensitic steels. This has generally been confirmed by the performed experiments. Z-phase precipitation seems to be a kinetic problem, and drivning force calculations using Thermo-Calc with the developed model have been used to predict steel compositions, which......The complex nitride Z-phase, Cr(V,Nb)N, has recently been identified as a major cause for premature breakdown in creep strength of a number of new 9-12%Cr martensitic steels. A thermodynamic model of the Z-phase has been created based on the Thermo-Calc software. The model predicts the Z...... will delay Z-phase precipitation....

  19. Effect of soaking temperature on microstructure and properties of 590 MPa grade hot-dip galvanized dual phase steel%均热温度对590 MPa级热镀锌双相钢组织与性能的影响

    Institute of Scientific and Technical Information of China (English)

    邝春福; 郑之旺; 王礞

    2016-01-01

    C-Mn steel were respectively soaked at 760 ℃, 800 ℃ and 850 ℃ for 120 s, and then rapidly cooled to 460 ℃ to simulate the hot-dip galvanizing. The pre-straining (2%) and baking treatment (170 ℃ for 20 min) were carried out to measure the BH values after annealing cycle. The influences of the soaking temperature on microstructure, mechanical properties and bake-hardening behavior of the 590 MPa grade hot-dip galvanized dual phase steel were investigated by means of microscope, SEM, tensile test machine and so on. The results show that the microstructure is composed of ferrite and martensite when annealed at 760-850 ℃, and no bainite is observed. Therefore, the tensile strength of the hot-dip galvanized dual phase steel reaches more than 590 MPa. The steel with excellent comprehensive properties (Rp0.2 =295 MPa, Rm =606 MPa, A=32. 1%, Rm × A=19 450 MPa·%) are obtained by annealing at 800 ℃. The BH value increases first and then decreases with increasing the soaking temperature from 760 ℃ to 850 ℃. And the BH value reaches maximum value (81 MPa) at the soaking temperature of 800 ℃.%将C-Mn钢分别加热至760、800和850℃均热120 s后,快速冷却至460℃以模拟热镀锌工艺。退火后对试验钢进行预应变(2%)和烘烤处理(170℃×20 min)以测量其烘烤硬化( BH)值。通过金相显微镜、扫描电镜、拉伸等技术,研究了均热温度对590 MPa级热镀锌双相钢微观组织、力学性能和烘烤硬化性能的影响。结果表明,在760~850℃范围内退火时,试验钢中未观察到贝氏体组织,微观组织由铁素体和马氏体组成,抗拉强度均达到590 MPa以上。热镀锌双相钢在800℃退火时,具有优良的综合力学性能,其屈服强度为295 MPa,抗拉强度为606 MPa,伸长率为32.1%,强塑积为19450 MPa·%。随着均热温度提高,BH值呈先增加后降低趋势;均热温度为800℃时,BH达最大值81 MPa。

  20. Decomposition of the MANET steel under dual-beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wanderka, N. [Hahn-Meitner-Institut Berlin (Germany); Camus, E. [Hahn-Meitner-Institut Berlin (Germany); Naundorf, V. [Hahn-Meitner-Institut Berlin (Germany); Keilonat, C. [Hahn-Meitner-Institut Berlin (Germany); Welzel, S. [Hahn-Meitner-Institut Berlin (Germany); Wollenberger, H. [Hahn-Meitner-Institut Berlin (Germany)

    1996-02-01

    Decomposition of the MANET steel was observed by means of atom probing after 300 keV Fe{sup +} ion irradiation to 50 dpa and simultaneous implantation of 15 keV He{sup +} ions at a rate of 200 appm/dpa. At irradiation temperatures of 673 and 698 K weak periodical variation of the chromium concentration was observed. At irradiation temperatures of 723 and 773 K clusters with chromium concentration of up to 25 at% were detected. (orig.).

  1. MARTENSITIC CREEP RESISTANT STEEL STRENGTHENED BY Z-PHASE

    DEFF Research Database (Denmark)

    2008-01-01

    % the following components: 9 to 15% Cr, 0.01-0.20% N, C in an amount less than 0.1%, one or more of: 0.01- 0.5%V,0.01-1%Nb, 0.01-2%Ta, and a balance being substantially iron and inevitable impurities. The invention further relates to a method of manufacturing such a steel alloy, a component comprising......The present invention relates to steel alloys having a martensitic or martensitic- ferritic structure and comprising Z-phase (CrXN) particles, where X is one or more of the elements V, Nb, Ta, and where the Z-phase particles have an average size of less than 400 nm. The alloy comprises by wt...... such a steel alloy, and to the use of such a steel alloy for high temperature components....

  2. Radiation induced microstructures in ODS 316 austenitic steel under dual-beam ions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, He Ken [Department of Mechanical and Materials Engineering, Queen’s University, Kingston K7L3N6, Ontario (Canada); Yao, Zhongwen, E-mail: yaoz@me.queensu.ca [Department of Mechanical and Materials Engineering, Queen’s University, Kingston K7L3N6, Ontario (Canada); Zhou, Zhangjian; Wang, Man [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Kaitasov, Odile [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, Orsay 91405 (France); Daymond, Mark R. [Department of Mechanical and Materials Engineering, Queen’s University, Kingston K7L3N6, Ontario (Canada)

    2014-12-15

    An ODS 316 austenitic steel was fabricated and irradiated using dual ion beams (1 MeV Kr{sup +} and 15 keV He{sup +}) with in-situ transmission electron microscope (TEM) observation. Cavities formed at a low dose in samples irradiated with simultaneous helium injection. It was found that Y–Ti–O particles acted as strong traps for cavity formation at low doses. Helium exhibited a significant effect on cavity development. Cavities were also preferentially nucleated along grain boundaries, phase boundaries and twin boundaries. Irradiation induced lattice defects mainly consisted of small 1/2〈1 1 0〉 perfect loops and 1/3〈1 1 1〉 Frank loops. An increment of helium injection rate also greatly enhanced the Frank loop growth. Small (<10 nm) Y–Ti–O particles were found to be unstable after irradiation to high doses. M{sub 23}C{sub 6} precipitates were observed after irradiation and helium might play a major role in their formation.

  3. High performance low cost steels with ultrafine grained and multi-phased microstructure

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Ultrafine grained ferrite was obtained through tempering cold rolled martensite with an average grain size of 200―400 nm in a low carbon and a microalloyed steel. Thermal and mechanical stability of the two steels was studied. Due to the pinning effect of microalloyed precipitates on the movement of dislocations and grain boundaries, the recrystallization and grain growth rate were retarded, and the thermal stability of ultrafine grained microstructure was improved. The ultrafine grained ferritic steel was strengthened, but its strain hardening rate was reduced. It seems that the tiny carbide precipitates have no significant effect on work hardening rate. The ultrafine grained ferrite+martensite dual phase microstructure was obtained in the microalloyed steel through intercritically annealing cold rolled martensite. The resulting multiphase microstructure has a tensile strength higher than 1.0 GPa with a yield ratio lower than 0.7. Another type of multiphase microstructure with nanoscaled lath bainite+ retained austenite was obtained through an isothermal heat treatment in low temperature bainite transformation region in high carbon steel. The tensile strength was as high as 1.64 GPa with a yield ratio of 0.84.

  4. A new nanoscale metastable iron phase in carbon steels

    Science.gov (United States)

    Liu, Tianwei; Zhang, Danxia; Liu, Qing; Zheng, Yanjun; Su, Yanjing; Zhao, Xinqing; Yin, Jiang; Song, Minghui; Ping, Dehai

    2015-10-01

    Metastable ω phase is common in body-centred cubic (bcc) metals and alloys, including high-alloying steels. Recent theoretical calculations also suggest that the ω structure may act as an intermediate phase for face-centred cubic (fcc)-to-bcc transformation. Thus far, the role of the ω phase played in fcc-bcc martensitic transformation in carbon steels has not been reported. In previous investigations on martensitic carbon steels, extra electron diffraction spots were frequently observed by transmission electron microscopy (TEM), and these spots were historically ascribed to the diffraction arising from either internal twins or carbides. In this paper, an intensive TEM investigation revealed that the extra spots are in fact attributed to the metastable ω phase in particle-like morphology with an overall size of several or dozens of nanometres. The strict orientation relationships between the ω phase and the ferrite matrix are in good agreement with those of the hexagonal (P6/mmm) ω phase in other bcc metals and alloys. The identification of the ω phase as well as the extra diffraction spots might provide a clue to help understand the physical mechanism of martensitic transformation in steels.

  5. A new nanoscale metastable iron phase in carbon steels

    Science.gov (United States)

    Liu, Tianwei; Zhang, Danxia; Liu, Qing; Zheng, Yanjun; Su, Yanjing; Zhao, Xinqing; Yin, Jiang; Song, Minghui; Ping, Dehai

    2015-01-01

    Metastable ω phase is common in body-centred cubic (bcc) metals and alloys, including high-alloying steels. Recent theoretical calculations also suggest that the ω structure may act as an intermediate phase for face-centred cubic (fcc)-to-bcc transformation. Thus far, the role of the ω phase played in fcc-bcc martensitic transformation in carbon steels has not been reported. In previous investigations on martensitic carbon steels, extra electron diffraction spots were frequently observed by transmission electron microscopy (TEM), and these spots were historically ascribed to the diffraction arising from either internal twins or carbides. In this paper, an intensive TEM investigation revealed that the extra spots are in fact attributed to the metastable ω phase in particle-like morphology with an overall size of several or dozens of nanometres. The strict orientation relationships between the ω phase and the ferrite matrix are in good agreement with those of the hexagonal (P6/mmm) ω phase in other bcc metals and alloys. The identification of the ω phase as well as the extra diffraction spots might provide a clue to help understand the physical mechanism of martensitic transformation in steels. PMID:26503890

  6. Electrical resistivity and phase transformation in steels

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, O.N.; Bhagat, A.N. [Tata Iron and Steel Company Limited, Jamshedpur (India)

    2003-01-01

    Changes in electrical resistance accompanying transformations in steels with magnetic change (e.g. {gamma} {yields} martensite/bainite) and without magnetic change (e.g. {gamma} {yields} {alpha}, above Curie temperature) have been examined; the former class affects the resistivity the latter does not. Next, while the efficacy of electrical resistivity measurement in capturing the well-known features of austenite stabilization (e.g. over - ageing, reversibility, and influence of prior martensite amount and so on) in high carbon steels has been reported in an earlier publication, new features (e.g. increase in resistance -increase at very low temperatures, change in temperature co-efficient of resistivity in the stabilized material etc.) are highlighted here. Finally, the work shows that a quantitative estimate of precipitation in the copper bearing, age-hardenable HSLA-100 steel during tempering can be done by continuous electrical resistivity measurement. These data also allow an in-depth kinetic analysis using the Johnson-Mehl-Avrami equation. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  7. Phase transformations and microstructure development in low alloy steel welds

    Energy Technology Data Exchange (ETDEWEB)

    Babu, S.S.; David, S.A.; Vitek, J.M. [and others

    1995-07-01

    Microstructure development in low alloy steel welds depends on various phase transformations that are a function of weld heating and cooling. The phase changes include non-metallic oxide inclusion formation in the liquid state, weld pool solidification, and solid state transformations. In this paper the mechanism of inclusion formation during low alloy steel welding is considered and the model predictions are compared with published results. The effect of inclusions on the austenite to ferrite transformation kinetics is measured and the mechanisms of transformation are discussed. The austenite gain development is related to the driving force for transformation of {delta} ferrite to austenite.

  8. Wavelength Phase-shift Dual-diffraction Interferometer

    Directory of Open Access Journals (Sweden)

    Geng-An Jiang

    2014-08-01

    Full Text Available This paper presents a wavelength phase-shift dual-diffraction interferometer for the displacement measurement. The measurement system is divided into two parts. On the part of the optical configuration, the grating displacement is converted into the phase of the light based on Doppler effect. By means of the dual-diffraction design, the phase sensitivity corresponding to the grating shift is enhanced. The second part is the phase analysis system. Because of the unbalance optical path design and the modulated wavelength, the wavelength phase-shift technique is developed for analyzing the phase variation resulted from the grating displacement. The experimental results demonstrate that this system has good stability and repeatability.

  9. Study of residual stresses in welded joints of dual phase HSLA steel used in automotive industry; Estudo das tensoes residuais em juntas soldadas de aco ARBL bifasico usado na industria automobilistica

    Energy Technology Data Exchange (ETDEWEB)

    Barbato, D.S.; Fonseca, M.P. Cindra; Marques Junior, A.S.; Chuvas, T.C.; Pardal, J.M., E-mail: mcindra@vm.uff.b [Universidade Federal Fluminense (PGMEC/UFF), Niteroi, RJ (Brazil). Programa de Pos-graduacao em Engenharia Mecanica; Berretta, J.R. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2010-07-01

    One way of weight reduction in automotive vehicles is through the use of high strength and low alloy (HSLA) steels, which enables the use of small thickness plates. Whereas the appearance of residual stresses is intrinsic to the welding process, this study evaluates the residual stresses generated in welded joints obtained by TIG and LASER welding processes and comparing them. Residual stresses were measured by X-rays diffraction technique, using a portable device with Cr{kappa}{alpha} radiation applying the double exposure method. It also evaluates the influence of shot peening treatment applied after welding, in the bend tests conducted for both welding conditions and TIG welded joints showed higher stability of compressive stresses after welding. The metallographic analysis by optical microscopy complemented the welded joints characterization. (author)

  10. Experimental and Numerical Simulations of Phase Transformations Occurring During Continuous Annealing of DP Steel Strips

    Science.gov (United States)

    Wrożyna, Andrzej; Pernach, Monika; Kuziak, Roman; Pietrzyk, Maciej

    2016-04-01

    Due to their exceptional strength properties combined with good workability the Advanced High-Strength Steels (AHSS) are commonly used in automotive industry. Manufacturing of these steels is a complex process which requires precise control of technological parameters during thermo-mechanical treatment. Design of these processes can be significantly improved by the numerical models of phase transformations. Evaluation of predictive capabilities of models, as far as their applicability in simulation of thermal cycles thermal cycles for AHSS is considered, was the objective of the paper. Two models were considered. The former was upgrade of the JMAK equation while the latter was an upgrade of the Leblond model. The models can be applied to any AHSS though the examples quoted in the paper refer to the Dual Phase (DP) steel. Three series of experimental simulations were performed. The first included various thermal cycles going beyond limitations of the continuous annealing lines. The objective was to validate models behavior in more complex cooling conditions. The second set of tests included experimental simulations of the thermal cycle characteristic for the continuous annealing lines. Capability of the models to describe properly phase transformations in this process was evaluated. The third set included data from the industrial continuous annealing line. Validation and verification of models confirmed their good predictive capabilities. Since it does not require application of the additivity rule, the upgrade of the Leblond model was selected as the better one for simulation of industrial processes in AHSS production.

  11. Phase instability of thermally aged CrMn austenitic steels

    Science.gov (United States)

    Ruedl, E.; Sasaki, T.

    1984-05-01

    The microstructural changes taking place in several commercial Cr-Mn austenitic steels during ageing at 873 and 1073 K were examined by analytical electron microscopy. Phase identification was obtained by electron diffraction, energy dispersive X-ray analysis and electron energy loss spectrometry. It was found that the phase changes depend on the carbon and nitrogen content of the materials as well as on the presence of Mo and delta ferrite.

  12. Investigations of morphological features of picosecond dual-wavelength laser ablation of stainless steel

    Science.gov (United States)

    Zhao, Wanqin; Wang, Wenjun; Mei, Xuesong; Jiang, Gedong; Liu, Bin

    2014-06-01

    Investigations on the morphological features of holes and grooves ablated on the surface of stainless steel using the picosecond dual-wavelength laser system with different powers combinations are presented based on the scarce researches on morphology of dual-wavelength laser ablation. The experimental results show the profiles of holes ablated by the visible beam appear V-shaped while those for the near-infrared have large openings and display U-shaped, which are independent of the ablation mechanism of ultrafast laser. For the dual-wavelength beam (a combination of visible beam and near-infrared), the holes resemble sunflower-like structures and have smoother ring patterns on the bottom. In general, the holes ablated by the dual-wavelength beam appear to have much flatter bottoms, linearly sloped side-walls and spinodal structures between the bottoms of the holes and the side-walls. Furthermore, through judiciously combining the powers of the dual-wavelength beam, high-quality grooves could be obtained with a flat worm-like structure at the bottom surface and less resolidified melt ejection edges. This study provides insight into optimizing ultrafast laser micromachining in order to obtain desired morphology.

  13. Monolithic GaAs Dual-Gate FET Phase Shifter.

    Science.gov (United States)

    1982-02-01

    and P. Hats-op. "Dual-gae MESPET phase stutter with gainappioodwsel the43*phas alltif (Fi. 6. Net apliier is atl 12 Hz." Elcron. Lett.. vol. 16. O.14...Park Redondo Beach, CA 90278 Watkins -Johnson Co. 1 E. J. Crescenzi, Jr./ Professor L. Eastman 1 K. Niclas Phillips Hall 3333 Hillview Ave. Cornell

  14. SIMULATION OF CHARACTERISTICS OF DUAL-CORE PHASE SHIFTING TRANSFORMER

    Directory of Open Access Journals (Sweden)

    Kalinin L.P.

    2014-04-01

    Full Text Available The role and importance of phase shifting transformers are increased as a result of the further development of integrated power systems. This gives the rise to new technical solutions which entails the necessity of comparison of new developments with existing. The article consider the technical characteristics of dual-core phase shifting transformer which later will be used as a basis for comparison with other competing options and assess of their technical efficiency.

  15. 先进高强度双相钢汽车板剪切断裂实验%Experimental Study of Shear Fracture on Advanced High Strength Dual-Phase Steels

    Institute of Scientific and Technical Information of China (English)

    李梅; 赵亦希; 胡星; 黄胜

    2011-01-01

    Fracture characteristics of advanced high strength DP(dual-phase) sheets in stretch-bending over a tight die radius were investigated through flanging and groove-shape dies.Flanging result shows the higher the strength grade of DP sheet is,the more chance shear fracture occurs.The groove-shape tests and simulations suggest the shear fracture around the tight radius only occurs under high BHF,and necking on the wall happens when BHF is low.The eventual failure mode during sheet metal forming operations of AHSS is viewed as the competition between necking and shear fracture,whichever criterion is satisfied first.%通过翻边实验和槽型件实验,研究了先进高强度双相(DP)钢在小半径拉弯成形中的断裂特性.翻边实验表明,高强度DP钢强度级别越高越容易发生剪切断裂.槽型件实验与仿真表明,高强度DP钢的断裂特性与压边力大小关系密切,压边力大则弯曲圆角处容易发生剪切断裂;压边力小则易在侧壁上发生颈缩断裂.先进高强度DP钢最终的断裂模式是剪切断裂和颈缩断裂相互竞争的结果,任一断裂条件先达到则板料发生该种断裂.

  16. High Energy Rate Forming Induced Phase Transition in Austenitic Steel

    Science.gov (United States)

    Kovacs, T.; Kuzsella, L.

    2017-02-01

    In this study, the effects of explosion hardening on the microstructure and the hardness of austenitic stainless steel have been studied. The optimum explosion hardening technology of austenitic stainless steel was researched. In case of the explosive hardening used new idea means indirect hardening setup. Austenitic stainless steels have high plasticity and can be cold formed easily. However, during cold processing the hardening phenomena always occurs. Upon the explosion impact, the deformation mechanism indicates a plastic deformation and this deformation induces a phase transformation (martensite). The explosion hardening enhances the mechanical properties of the material, includes the wear resistance and hardness [1]. In case of indirect hardening as function of the setup parameters specifically the flayer plate position the hardening increased differently. It was find a relationship between the explosion hardening setup and the hardening level.

  17. Thermodynamic Analysis on Precipitated Phases in Low Activation Steel

    Directory of Open Access Journals (Sweden)

    PANG Qi-hang

    2016-07-01

    Full Text Available A type of low-carbon reduced activation ferritic/martensitic (RAFM steel is designed.The microstructure and mechanical properties of tested steels prepared by different technologies were investigated by means of scanning electron microscope, transmission electron microscope and tensile test. The chemical composition of precipitations of tested steels are inspected by energy dispersive spectroscopy (EDS, meanwhile the law of precipitation phase of low carbon low activation FM steel was studied by thermodynamic calculations. The results show that the best mechanical properties are obtained by tempering at 750℃ for 1h after quenched from heating at 980℃ for 1h.The low carbon RAFM steel meeting performance standards can be produced. The precipitations are composed of M23C6 and MX.M23C6 carbide precipitates mainly in the process of below 950℃ rolling and heat treatment. However MX mainly precipitates in the process of rolling, and the secondary precipitation seldom occurs during the process of heat treatment and rapid cooling.

  18. Metastable high-entropy dual-phase alloys overcome the strength-ductility trade-off

    Science.gov (United States)

    Li, Zhiming; Pradeep, Konda Gokuldoss; Deng, Yun; Raabe, Dierk; Tasan, Cemal Cem

    2016-06-01

    Metals have been mankind’s most essential materials for thousands of years; however, their use is affected by ecological and economical concerns. Alloys with higher strength and ductility could alleviate some of these concerns by reducing weight and improving energy efficiency. However, most metallurgical mechanisms for increasing strength lead to ductility loss, an effect referred to as the strength-ductility trade-off. Here we present a metastability-engineering strategy in which we design nanostructured, bulk high-entropy alloys with multiple compositionally equivalent high-entropy phases. High-entropy alloys were originally proposed to benefit from phase stabilization through entropy maximization. Yet here, motivated by recent work that relaxes the strict restrictions on high-entropy alloy compositions by demonstrating the weakness of this connection, the concept is overturned. We decrease phase stability to achieve two key benefits: interface hardening due to a dual-phase microstructure (resulting from reduced thermal stability of the high-temperature phase); and transformation-induced hardening (resulting from the reduced mechanical stability of the room-temperature phase). This combines the best of two worlds: extensive hardening due to the decreased phase stability known from advanced steels and massive solid-solution strengthening of high-entropy alloys. In our transformation-induced plasticity-assisted, dual-phase high-entropy alloy (TRIP-DP-HEA), these two contributions lead respectively to enhanced trans-grain and inter-grain slip resistance, and hence, increased strength. Moreover, the increased strain hardening capacity that is enabled by dislocation hardening of the stable phase and transformation-induced hardening of the metastable phase produces increased ductility. This combined increase in strength and ductility distinguishes the TRIP-DP-HEA alloy from other recently developed structural materials. This metastability-engineering strategy should

  19. Quantifying the effects of tempering on individual phase properties of DP980 steel with nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, G.; Zhang, F.; Ruimi, A.; Field, D. P.; Sun, X.

    2016-06-01

    We conduct a series of thermal and mechanical testing on a commercial dual phase (DP) 980 steel in order to quantify the effects of tempering on its individual phase properties. Tempering treatment is conducted at 250 °C and 400 °C for 60 minutes each. Ferrite and martensite grains are distinguished using electron backscatter diffraction (EBSD) and scanning probe microscopy (SPM), and the martensite volume fractions (MVF) are determined based on the image quality (IQ) map. Multi-scale indentation tests combined with a newly developed inverse method are used to obtain the individual phase flow properties in each tempered DP980 sample. The results show that, i) tempering significantly reduces martensite yield strength, while it only slightly reduces the ferrite yield strength; ii) tempering temperature has a more significant influence on the work hardening exponent of ferrite than that of martensite; iii) the elastic modulus of martensite is consistently higher than that of ferrite. As a validation, a simple rule of mixtures is used to verify the above-predicted individual phase flow stresses with the experimentally obtained overall true stress vs. true strain curves. The methodology and the corresponding results shown in this study can help guide the selection of tempering parameters in optimizing the mechanical properties of DP steels for their intended applications.

  20. DP1180双相钢在高应变速率变形条件下应变硬化行为及机制%BEHAVIOUR AND MECHANISM OF STRAIN HARDENING FOR DUAL PHASE STEEL DP1180 UNDER HIGH STRAIN RATE DEFORMATION

    Institute of Scientific and Technical Information of China (English)

    代启锋; 宋仁伯; 范午言; 郭志飞; 关小霞

    2012-01-01

    Strain hardening behaviour and mechanism of a cold-rolled dual phase steel DP1180 under quasi-static tensile condition at a strain rate of 0.001 s-1 by electronic universal testing machine, and dynamic tensile condition at strain rates of 500 and 1750 s-1 by split Hopkinson tensile bar (SHTB) apparatus were systematically studied. According to the modified Swift true strain-stress model, the experimental data was regressed by using nonlinear fitting method, and strain hardening exponent in the modified Swift model was calculated by a modified Crussard-Jaoul method. The results revealed that there are two stage strain hardening characteristics of DP 1180 steel at the strain rate range of 0.001-1750 s-1, the strain hardening ability of the stage Ⅰ was enhanced with increase of strain rate, while the strain hardening ability of the stage Ⅱ was weakened, and the transition strain was decreased. The ferrite near the martensite regions formed cell blocks with dislocation structures, with a size of 90 nm, due to the limit of deformation compatibility, and the existence of geometrically necessary boundary (GNB) made DP1180 steel not instantly damaged under deformation at high strain rates. In addition, the adiabatic temperature rise of △T= 103 ℃ made martensite easy to have plastic deformation at a strain rate of 1750 s-1.%利用电子万能试验机和分离式Hopkinson拉杆装置对DP1180冷轧双相钢分别进行应变速率为0.001 s-1和500,1750 s-1的准静态和动态拉伸实验,根据修正的Swift真应力 应变模型对实验数据进行了非线性拟合,并用修正的Crussard-Jaoul分析法计算出修正的Swift模型的应变硬化指数.结果表明:在准静态和动态拉伸下,都存在两阶段应变硬化特性,第一阶段随应变速率的增加应变硬化能力增强;第二阶段随应变速率的增加应变硬化能力减弱;转折应变随应变速率的增加从3.12%减小到1.28%.在高应变速率下,马氏体附近的铁

  1. Protection of Lithium (Li) Anodes Using Dual Phase Electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Mikhaylik, Yuriy [Sion Power Corporation, Tucson, AZ (United States)

    2014-09-30

    Sion Power focused on metallic lithium anode protection, employing the Dual-Phase Electrolyte approach. The objective of this project was to develop a unique electrolyte providing two liquid phases having good Li+ conductivity, self-partitioning and immiscibility, serving separately the cathode and anode electrodes. This Dual-Phase Electrolyte was combined with thin film multi-layer, physical barrier membranes developed partially under a separate ARPA-E funded project. All these protective structures were stabilized by externally applied pressure. This strategy was used for Li-S cells. The development directly addressed cell safety, particularly higher thermal stability, while also allowing higher energies and cycle life. Safety tests showed that 100% of cells with Dual-Phase Electrolyte were intact and did not exhibit thermal runaway up to 178 °C and thus met the project objective of increasing the runaway temperature to >165°C. Cells also passed cycling at USABC Dynamic Stress Test conditions developed for Electric Vehicle applications and generated specific energy > 300 Wh/kg.

  2. Shear Fracture of Dual Phase AHSS in the Process of Stamping: Macroscopic Failure Mode and Micro-level Metallographical Observation

    Science.gov (United States)

    Wang, Wurong; Wei, Xicheng; Yang, Jun; Shi, Gang

    2011-08-01

    Due to its excellent strength and formability combinations, dual phase (DP) steels offer the potential to improve the vehicle crashworthiness performance without increasing car body weight and have been increasingly used into new vehicles. However, a new type of crack mode termed as shear fracture is accompanied with the application of these high strength DP steel sheets. With the cup drawing experiment to identify the limit drawing ratio (LDR) of three DP AHSS with strength level from 600 MPa to 1000 MPa, the study compared and categorized the macroscopic failure mode of these three types of materials. The metallographical observation along the direction of crack was conducted for the DP steels to discover the micro-level propagation mechanism of the fracture.

  3. Stable phases in aged type 321 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Bentley, J.; Leitnaker, J.M.

    1978-01-01

    X-ray diffraction and Analytical Electron Microscopy have been used to characterize the precipitate phases present in type 321 stainless steel after 17 years of service at approximately 600/sup 0/C. The morphology, crystallography, and orientation relationships with the matrix of the precipitates have been determined along with the chemical composition of several of the phases. Long-term aging of type 321 stainless steel indicates TiC, not M/sub 23/C/sub 6/, is the stable carbide phase. A theory is developed to explain appearance of M/sub 23/C/sub 6/ at intermediate times. The theory also indicates the means for preventing M/sub 23/C/sub 6/ formation and hence sensitization of the steel to intergranular corrosion. The amount of sigma found correlates well with results from shorter time studies. Ti/sub 4/C/sub 2/S/sub 2/ and a complex phosphide-arsenide were also present.

  4. Progress in the development of steels satisfying special demands of the markets

    Energy Technology Data Exchange (ETDEWEB)

    Bulla, W.; Lauprecht, W.E.; Diesburg, D.E.

    1981-11-16

    Large-diameter pipes, effect of seawater on steel, reduction of weight (automobile construction) and more stringent demands are discussed in the following chapters: Steels for oil- and gas-field pipes; large-diameter pipes; dual-phase steel; case-hardened steels for gear parts; creep-resistant components; high-alloy stainless steels for the chemical industry, environment and sea water.

  5. A dual-electrochemical cell to study the biocorrosion of stainless steel.

    Science.gov (United States)

    Lopes, F A; Perrin, S; Féron, D

    2007-01-01

    The presence of microorganisms on metal surfaces can alter the local physical/chemical conditions and lead to microbiologically influenced corrosion (MIC). The goal of the present work was to study the effect of a mixed aerobic-anaerobic biofilm on the behaviour of stainless steel (316 L) in underground conditions. Rather than testing different bacteria or consortia, investigations were based on the mechanisms of MIC. Mixed biofilms were simulated by the addition of glucose oxidase to reproduce the aerobic conditions and by sulphide or sulphate-reducing bacteria (SRB) for the anaerobic conditions. A double thermostated electrochemical cell has been developed to study the coupling between aerobic and anaerobic conditions. Results suggested a transfer of electrons from the stainless steel sample of the anaerobic cell to the stainless steel sample of the aerobic one. Inorganic sulphide was replaced by SRB in the anaerobic cell revealing an increase of the galvanic current which may be explained by an effect of lactate and/or acetate on the anodic reaction or by a high sulphide concentration in the biofilm. The results of this study underline that the dual-electrochemical cell system is representative of phenomena present in natural environments and should be considered as an option when studying MIC.

  6. protoDUNE-Single Phase and protDUNE-DualPhase

    CERN Multimedia

    Brice, Maximilien

    2016-01-01

    At the EHN1 two big 8m x 8m x8m detector prototypes (protoDUNE-Single Phase and protDUNE-DualPhase) are being constructed. The aim is to test technologies and detector performances for DUNE, a new generation of LBN neutr

  7. Structural control of void formation in dual phase steels

    DEFF Research Database (Denmark)

    Azuma, Masafumi

    measurements, tensile tests and hole-expansion tests. The initial microstructure and the deformed microstructure were characterized by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In situ tensile tests in a SEM were applied for direct observation of the void formation...

  8. Thermal analysis of high temperature phase transformations of steel

    Directory of Open Access Journals (Sweden)

    K. Gryc

    2013-10-01

    Full Text Available The series of thermal analysis measurements of high temperature phase transformations of real grain oriented electrical steel grade under conditions of two analytical devices (Netzsch STA 449 F3 Jupiter; Setaram SETSYS 18TM were carried out. Two thermo analytical methods were used (DTA and Direct thermal analysis. The different weight of samples was used (200 mg, 23 g. The stability/reproducibility of results obtained by used methodologies was verified. The liquidus and solidus temperatures for close to equilibrium conditions and during cooling (20 °C/min; 80 °C/min were determined. It has been shown that the higher cooling rate lead to lower temperatures for start and end of solidification process of studied steel grade.

  9. 冲压、回弹及应变速率对双相钢成形件碰撞性能影响的模拟%Simulation about the Influence of Stamping, Springback and Strain Rate on Collision Performance of Dual-Phase Steel Parts

    Institute of Scientific and Technical Information of China (English)

    朱国明; 康永林; 吕超

    2011-01-01

    Based on cold rolled galvanized dual-phase steel sheet, collision analysis model of closed hat section beam was established on the basis of simulation analysis of U-beam stamping and springback. Mapping was used to transfer results of thickness, stress and strain of U-beam to impact structural component. Collision processes of closed hat section were analyzed by considering the influence of stamping, springback, strain rate and so on. The results show that the strain rate was higher in the process of collision and its influence was most apparent and should be specially considered in the definition of model. Due to the work hardening and thickness reduction in metal deformation, the stamping results affected simulative results of the collision process directly. Residual stress was weaker due to the stress released from the inside of the component after stamping. Therefore, greater external force was needed to produce the same degree of collision, and rigid wall reaction force considered springbaek was higher than that no considering.%针对冷轧镀锌双相钢板,在完成U型梁冲压成形及回弹模拟分析的基础上,建立了闭口帽型梁的碰撞分析模型;采用映射的方法完成了U型梁的厚度、应力、应变向碰撞结构件的结果传递;在考虑冲压成形、回弹及应变速率等的情况下,对帽型梁的碰撞过程进行了模拟分析。结果表明:在碰撞过程中,由于应变速率较高,它的影响最为明显,在模型的定义过程中需要着重考虑;因为金属变形过程的加工硬化和厚度减薄等因素的影响,冲压结果直接影响碰撞过程的模拟结果;冲压后因回弹使零件内部的应力得到释放,残余应力减小,因此导致碰撞过程中产生相同的变形需要更

  10. Linear programming phase unwrapping for dual-wavelength digital holography.

    Science.gov (United States)

    Wang, Zhaomin; Jiao, Jiannan; Qu, Weijuan; Yang, Fang; Li, Hongru; Tian, Ailing; Asundi, Anand

    2017-01-20

    A linear programming phase unwrapping method in dual-wavelength digital holography is proposed and verified experimentally. The proposed method uses the square of height difference as a convergence standard and theoretically gives the boundary condition in a searching process. A simulation was performed by unwrapping step structures at different levels of Gaussian noise. As a result, our method is capable of recovering the discontinuities accurately. It is robust and straightforward. In the experiment, a microelectromechanical systems sample and a cylindrical lens were measured separately. The testing results were in good agreement with true values. Moreover, the proposed method is applicable not only in digital holography but also in other dual-wavelength interferometric techniques.

  11. Dual Edge Triggered Phase Detector for DLL and PLL Applications

    Directory of Open Access Journals (Sweden)

    Prasanna Kumar L

    2015-05-01

    Full Text Available An ASIC design of Dual Edge Triggered Phase Detector(DET PD for Delay locked loop(DLL and Phase locked loop(PLL applications is proposed in this paper.The proposed DET PD has high locking speed and less jitter. The designs are based on TSPC flip flop logic, which overcomes the issue of narrow capture range. The Double edge triggered phase detector dissipates less power than conventional designs and can be operated at a frequency range of 250MHz to 1GHz.The proposed DET-PD is designed using 180nm CMOS process technology at a 1.8V supply voltage in cadence virtuoso and circuit simulated in cadence spectre.

  12. MICROALLOYED STEELS FOR THE AUTOMOTIVE INDUSTRY

    Directory of Open Access Journals (Sweden)

    Debanshu Bhattacharya

    2014-12-01

    Full Text Available Two major drivers for the use of newer steels in the automotive industry are fuel efficiency and increased safety performance. Fuel efficiency is mainly a function of weight of steel parts, which in turn, is controlled by gauge and design. Safety is determined by the energy absorbing capacity of the steel used to make the part. All of these factors are incentives for the U.S. automakers to use both Highly Formable and Advanced High Strength Steels (AHSS to replace the conventional steels used to manufacture automotive parts in the past. AHSS is a general term used to describe various families of steels. The most common AHSS is the dual-phase steel that consists of a ferrite-martensite microstructure. These steels are characterized by high strength, good ductility, low tensile to yield strength ratio and high bake hardenability. Another class of AHSS is the complex-phase or multi-phase steel which has a complex microstructure consisting of various phase constituents and a high yield to tensile strength ratio. Transformation Induced Plasticity (TRIP steels is another class of AHSS steels finding interest among the U.S. automakers. These steels consist of a ferrite-bainite microstructure with significant amount of retained austenite phase and show the highest combination of strength and elongation, so far, among the AHSS in use. High level of energy absorbing capacity combined with a sustained level of high n value up to the limit of uniform elongation as well as high bake hardenability make these steels particularly attractive for safety critical parts and parts needing complex forming. A relatively new class of AHSS is the Quenching and Partitioning (Q&P steels. These steels seem to offer higher ductility than the dual-phase steels of similar strengths or similar ductility as the TRIP steels at higher strengths. Finally, martensitic steels with very high strengths are also in use for certain parts. The most recent initiative in the area of AHSS

  13. Processing of low Carbon steel by dual rolls equal channel extrusion

    Science.gov (United States)

    Rusz, S.; Cizek, L.; Salajka, M.; Kedron, J.; Tylsar, S.

    2014-08-01

    This paper introduces a new method of forming for achievement of grain structure refinement by processing in DRECE (Dual Rolls Equal Channel Extrusion) equipment. The DRECE device was developed at the VSB - Technical University of Ostrava. It allows grain refinement in strip plate with dimensions of 58 mm (width) × 2 mm (thickness) × 1000 mm (length). The influence of the number of passes on the mechanical properties and related structure refinement was examined experimentally. The effect of a heat treatment (500 °C/1 h/steady air) on the grain refinement of low carbon steel after severe plastic deformation is analysed. Through this novel technique, the grain structure can be converted into a submicron grain structure.

  14. Influence of notch orientation and temperature on the impact behavior of a dual hardness steel composite

    Energy Technology Data Exchange (ETDEWEB)

    Weber, R.P. [Seção de Engenharia Mecânica e de Materiais/Instituto Militar de Engenharia/ Praça General Tibúrcio, 80, 22290-270 Rio de Janeiro, RJ (Brazil); Chawla, K.K. [Department of Materials Science and Engineering/The University of Alabama at Birmingham/Birmingham, AL 35294 (United States); Miguez Suarez, J.C., E-mail: jmiguez@ime.eb.br [Seção de Engenharia Mecânica e de Materiais/Instituto Militar de Engenharia/ Praça General Tibúrcio, 80, 22290-270 Rio de Janeiro, RJ (Brazil)

    2013-09-15

    The need for materials with good characteristics for critical applications, such as in defense and aerospace, has led to the development of new metallic materials. In the present work the impact fracture behavior of a dual hardness steel composite was studied in two geometries, “crack arrester” and “crack divider”. The composite was produced by forging and rolling followed by treatments of quenching and tempering and then annealing. The composite was characterized by optical microscopy as well as hardness, microhardness, tensile and impact tests. The failure mechanisms in impact at different temperatures were analyzed by scanning electron microscopy. The results showed that the mechanical behavior was significantly affected by the heat treating processes, with higher impact resistance associated with the crack arrester orientation. These results are analyzed in terms of the state of stress at the crack tip.

  15. Dual-phase cardiac diffusion tensor imaging with strain correction.

    Directory of Open Access Journals (Sweden)

    Christian T Stoeck

    Full Text Available In this work we present a dual-phase diffusion tensor imaging (DTI technique that incorporates a correction scheme for the cardiac material strain, based on 3D myocardial tagging.In vivo dual-phase cardiac DTI with a stimulated echo approach and 3D tagging was performed in 10 healthy volunteers. The time course of material strain was estimated from the tagging data and used to correct for strain effects in the diffusion weighted acquisition. Mean diffusivity, fractional anisotropy, helix, transverse and sheet angles were calculated and compared between systole and diastole, with and without strain correction. Data acquired at the systolic sweet spot, where the effects of strain are eliminated, served as a reference.The impact of strain correction on helix angle was small. However, large differences were observed in the transverse and sheet angle values, with and without strain correction. The standard deviation of systolic transverse angles was significantly reduced from 35.9±3.9° to 27.8°±3.5° (p<0.001 upon strain-correction indicating more coherent fiber tracks after correction. Myocyte aggregate structure was aligned more longitudinally in systole compared to diastole as reflected by an increased transmural range of helix angles (71.8°±3.9° systole vs. 55.6°±5.6°, p<0.001 diastole. While diastolic sheet angle histograms had dominant counts at high sheet angle values, systolic histograms showed lower sheet angle values indicating a reorientation of myocyte sheets during contraction.An approach for dual-phase cardiac DTI with correction for material strain has been successfully implemented. This technique allows assessing dynamic changes in myofiber architecture between systole and diastole, and emphasizes the need for strain correction when sheet architecture in the heart is imaged with a stimulated echo approach.

  16. Sigma Phase Precipitation and Properties of Super-duplex Stainless Steel UNS S32750 Aged at the Nose Temperature

    Institute of Scientific and Technical Information of China (English)

    ZOU Dening; HAN Ying; ZHANG Wei; YU Junhui

    2011-01-01

    The nose temperature for σ-phase precipitation in super-duplex stainless steel (SDSS) UNS S32750 was evaluated by hardness method. Color-optical microscopy, scanning electron microscopy, energy spectrum analysis, impact and corrosion testing were carried out to investigate characteristics of microstructure and properties of the SDSS aged at the nose temperature. The experimental results indicate that the nose temperature of precipitation is 920 ℃ and aging at this temperature tiny σ phases can precipitate at phase interfaces or ferrite grain boundaries within 2 min.Prolonging aging duration the amount of σ-phase increases and a dual structure with σ and γ is obtained when aging for 120 min. The precipitation of σ-phase leads to severe deterioration in impact toughness (longitudinal/transverse direction) and corrosion resistance of SDSS.

  17. A new dual bracing system for improving the seismic behavior of steel structures

    Science.gov (United States)

    Kari, A.; Ghassemieh, M.; Abolmaali, S. A.

    2011-12-01

    Shape memory alloy braces and buckling restrained braces have been shown to exhibit favorable energy dissipating characteristics in steel structures. However, buckling restrained braces are unable to recover their original shape after unloading and consequently experience large residual inter-story drifts after the earthquake, which leads to large permanent deformations in the structure. On the other hand, shape memory braces possess the recentering feature which enables them to recover their original shape. Nevertheless, compared to buckling restrained braced frames, the shape memory bracing frame usually experiences larger maximum inter-story drifts during the earthquake. This paper presents the results of a numerical study conducted to investigate the benefit of using the combination of buckling restrained braces and shape memory braces (dual bracing) in one structure, for the new design as well as retrofitting purposes. The superelastic model of shape memory alloy and plasticity model of steel are incorporated into the nonlinear finite element program particularly developed for this research. Results revealed that, with the proper configuration, both aims, namely minimizing both residual and maximum inter-story drifts, can be attained.

  18. Yearly progress report on WA105/ProtoDUNE dual-phase (2017)

    CERN Document Server

    Aimard, B

    2017-01-01

    WA105/ProtoDUNE dual-phase aims at fully demonstrating the concept of a very large dual-phase LAr TPC and calibrating it with a charged particles test beam, in view of the application of this detector design for the construction of DUNE 10 kton far detector modules. In this document we report the general progress of the dual-phase experimental activities at CERN since the last SPSC yearly report.

  19. A new 12% chromium steel strengthened by Z-phase precipitates

    DEFF Research Database (Denmark)

    Liu, Fang; Rashidi, Masoud; Johansson, Lennart

    2016-01-01

    steel was produced and creep tested. The steel exhibited good long-term creep resistance. Dense nano-sized Z-phase precipitates were formed at an early stage, and coarsened slowly. They remained small after more than 10,000 h. (C) 2015 Elsevier Ltd. All rights reserved.......In order to increase the corrosion resistance and simultaneously maintain the creep resistance of 9-12% Cr steels at 650 degrees C, a new alloy design concept was proposed, using thermodynamically stable Z-phase (CrTaN) precipitates to strengthen the steel. A new trial Z-phase strengthened 12% Cr...

  20. A 3rd Generation Advanced High-Strength Steel (AHSS) Produced by Dual Stabilization Heat Treatment (DSHT)

    Science.gov (United States)

    Qu, Hao; Michal, Gary M.; Heuer, Arthur H.

    2013-10-01

    A 3rd generation advanced high-strength steel containing, in wt pct, 0.3 C, 4.0 Mn, 1.5 Al, 2.1 Si, and 0.5 Cr has been produced using a dual stabilization heat treatment—a five stage thermal processing schedule compatible with continuous galvanized steel production. In excess of 30 vol pct retained austenite containing at least 0.80 wt pct C was achieved with this alloy, which had tensile strengths up to 1650 MPa and tensile elongations around 20 pct.

  1. Precipitation process of Z-phase in 9-12%CR steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson

    2014-01-01

    Precipitation of Z-phase, Cr(V,Nb)N, is known to negatively affect creep properties of 9-12%Cr steels for power plant applications as it dissolves finely distributed MX particles, (V,Nb)N, especially in high Cr steels. As the Z-phase precipitates slowly as large particles, this causes a net drop...

  2. Theory and Modeling of Phase Transformations under Stress in Steel

    Institute of Scientific and Technical Information of China (English)

    T.Y. Hsu (XU Zu-yao)

    2004-01-01

    Thermodynamic prediction of the increment of the formation temperature of proeutectoid ferrite by applied stress is nearly consistent with the experimental data. Kinetics models for ferrite, pearlite and bainite transformations can be shown as modified Johnson-Mehl-Avrami equation in which parameter b(σ) varies with the level of applied stress.The effects of tensile and compressive stresses on enhancement of the ferrite/pearlite and bainite transformations are discussed. The necessity and approach of modification of additivity hypothesis are introduced and the results from modified equation in which some parameters are obtained by regression of two experimental results or taken from TTT and CCT diagrams of a certain steel are superior than that from Scheil's equation. Thermodynamic calculation of Ms and nucleation kinetics equations of martensitic transformation under stress are suggested. Modeling of phase transformations under stress in ferrous alloys is briefly described.

  3. Position Reconstruction in a Dual Phase Xenon Scintillation Detector

    CERN Document Server

    Solovov, V N; Akimov, D Yu; Araújo, H M; Barnes, E J; Burenkov, A A; Chepel, V; Currie, A; DeViveiros, L; Edwards, B; Ghag, C; Hollingsworth, A; Horn, M; Kalmus, G E; Kobyakin, A S; Kovalenko, A G; Lebedenko, V N; Lindote, A; Lopes, M I; Lüscher, R; Majewski, P; Murphy, A St J; Neves, F; Paling, S M; da Cunha, J Pinto; Preece, R; Quenby, J J; Reichhart, L; Scovell, P R; Silva, C; Smith, N J T; Smith, P F; Stekhanov, V N; Sumner, T J; Thorne, C; Walker, R J

    2011-01-01

    We studied the application of statistical reconstruction algorithms, namely maximum likelihood and least squares methods, to the problem of event reconstruction in a dual phase liquid xenon detector. An iterative method was developed for in-situ reconstruction of the PMT light response functions from calibration data taken with an uncollimated gamma-ray source. Using the techniques described, the performance of the ZEPLIN-III dark matter detector was studied for 122 keV gamma-rays. For the inner part of the detector (R<100 mm), spatial resolutions of 13 mm and 1.6 mm FWHM were measured in the horizontal plane for primary and secondary scintillation, respectively. An energy resolution of 8.1% FWHM was achieved at that energy. The possibility of using this technique for improving performance and reducing cost of scintillation cameras for medical applications is currently under study.

  4. Dual-Polarized Planar Phased Array Analysis for Meteorological Applications

    Directory of Open Access Journals (Sweden)

    Chen Pang

    2015-01-01

    Full Text Available This paper presents a theoretical analysis for the accuracy requirements of the planar polarimetric phased array radar (PPPAR in meteorological applications. Among many factors that contribute to the polarimetric biases, four factors are considered and analyzed in this study, namely, the polarization distortion due to the intrinsic limitation of a dual-polarized antenna element, the antenna pattern measurement error, the entire array patterns, and the imperfect horizontal and vertical channels. Two operation modes, the alternately transmitting and simultaneously receiving (ATSR mode and the simultaneously transmitting and simultaneously receiving (STSR mode, are discussed. For each mode, the polarimetric biases are formulated. As the STSR mode with orthogonal waveforms is similar to the ATSR mode, the analysis is mainly focused on the ATSR mode and the impacts of the bias sources on the measurement of polarimetric variables are investigated through Monte Carlo simulations. Some insights of the accuracy requirements are obtained and summarized.

  5. Aluminizing of plain carbon steel: Effect of temperature on coating and alloy phase morphology at constant holding time

    OpenAIRE

    Isiko, Maureen Bangukira

    2012-01-01

    Aluminized steel possesses excellent physical, chemical and mechanical properties as compared to plain carbon steel. This type of steel has found application in high temperature, oxidizing and corrosive environments. In addition, aluminized steel is more cost effective than stainless steels. The objective of the current study is to study effect of temperature on the thicknesses and phase morphology of the coating and intermetallic layer that is formed during hot-dip aluminizing of steel at a ...

  6. Initial study on Z-phase strengthened 9-12% Cr steels by atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fang; Andren, Hans-Olof [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Applied Physics

    2010-07-01

    The microstructure of two different types of Z-phase strengthened experimental steels, CrNbN-based or CrTaN-based, was investigated. Both steels underwent aging at 650 C for relatively short period of time, 24 hours or 1005 hours. Atom probe tomography was used to study the chemical composition of the matrix and precipitates, and the size and number density of the small precipitates. Both steels contain Laves phase at prior austenite grain boundaries and martensitic lath boundaries. The CrTaN-based steel was found more promising due to its finer and more densely distributed precipitates after 1005 hour aging. (orig.)

  7. EFFECT OF INTERMETALLIC PHASES ON CORROSION BEHAVIOR AND MECHANICAL PROPERTIES OF DUPLEX STAINLESS STEEL AND SUPER-DUPLEX STAINLESS STEEL

    Directory of Open Access Journals (Sweden)

    Prabhu Paulraj

    2015-08-01

    Full Text Available Duplex Stainless Steels (DSS and Super Duplex Stainless Steel (SDSS have excellent integration of mechanical and corrosion properties. However, the formation of intermetallic phases is a major problem in their usage. The mechanical and corrosion properties are deteriorated due to the presence of intermetallic phases. These phases are induced during welding, prolonged exposure to high temperatures, and improper heat treatments. The main emphasis of this review article is on intermetallic phases and their effects on corrosion and mechanical properties. First the effect of various alloying elements on DSS and SDSS has been discussed followed by formation of various intermetallic phases. The intermetallic phases affect impact toughness and corrosion resistance significantly. Their deleterious effect on weldments has also been reviewed.

  8. Neodymium-rich precipitate phases in a high-chromium ferritic/martensitic steel

    Science.gov (United States)

    Shen, Yinzhong; Zhou, Xiaoling; Shang, Zhongxia

    2016-05-01

    Neodymium being considered as nitride forming element has been used in a design of advanced ferritic/martensitic (FM) steels for fossil fired power plants at service temperatures of 630 °C to 650 °C to effectively improve the creep strength of the steels. To fully understand the characteristics of neodymium precipitates in high-Cr FM steels, precipitate phases in an 11Cr FM steel with 0.03 wt% addition of Nd have been investigated by transmission electron microscopy. Three neodymium phases with a face-centered cubic crystal structure and different composition were observed in the steel. They consisted of neodymium carbonitride with an average lattice parameter of 1.0836 nm, Nd-rich carbonitride mainly containing Mn, and Nd-rich MN nitride mainly containing Mn and Co. Other three Nd-rich and Nd-containing phases, which appear to be Nd-Co-Cr/Nd-rich intermetallic compounds and Cr-Fe-rich nitride containing Nd, were also detected in the steel. Nd-relevant precipitates were found to be minor phases compared with M23C6 and Nb/V/Ta-rich MX phases in the steel. The content of Nd in other precipitate phases was very low. Most of added Nd is considered to be present as solid solution in the matrix of the steel.

  9. Microstructure of Z-phase strengthened martensitic steels: Meeting the 650°C challenge

    DEFF Research Database (Denmark)

    Liu, Fang; Rashidi, Masoud; Hald, John

    2017-01-01

    We studied three series of Z-phase strengthened steels using scanning electron microscopy, transmission electron microscopy, and atom probe tomography to reveal the detailed microstructure of these steels. In particular, the phase transformation from M(C,N) to Z-phase (CrMN) was studied. Carbon...... content in the steels is the governing factor in this transformation. The impact toughness of some test alloys was rather low. This is attributed to the formation of a continuous W-rich film along prior austenite grain boundaries. Cu and C addition to the test alloys changed Laves phase morphology...... to discrete precipitates and improved toughness dramatically. BN particles were found in some steels. Formation of BN is directly linked to the B concentration in the steels....

  10. Microstructure evolution of selected ferritic-martensitic steels under dual-beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wanderka, N.; Camus, E.; Wollenberger, H. [Hahn-Meitner-Inst. Berlin GmbH (Germany)

    1997-11-01

    The authors present experimental results on the microstructure evolution of dual-beam irradiated (300 keV heavy ions plus 15 keV helium ions) ferritic-martensitic steels (Manet, DIN 1.4926, F82H mod). The helium bubble morphology as well as microchemistry of the alloys are investigated by means of transmission electron microscopy and field-ion microscopy with atom probe. The alloys were irradiated to fluences up to 50 dpa and implanted with helium up to a concentration of 1 at.% at the temperatures of 723 K and 773 K. The damage and implantation rates varied from 2.5 {center_dot} 10{sup {minus}3} dpa/s to 2.5 {center_dot} 10{sup {minus}2} dpa/s and from 0.5 appm/s to 5 appm/s, respectively. Size and number density of helium bubbles is found to be rate dependent. Smaller implantation rates produce larger helium bubbles and smaller bubble number densities. Regions of local enrichment of alloy elements, typically 5 nm in size, containing chromium (up to 40 at.%), silicon, and nickel are detected. Number densities of helium bubbles and of regions of chromium enrichments are comparable and lie between 10{sup 23}/m{sup 3} and 10{sup 24}/m{sup 3}. Possible extrapolation of the present ion irradiations to spallation source and fusion reactor conditions is shortly addressed.

  11. Residual formability of preformed and subsequently welded advanced high strength steels (Reform): Final Report

    OpenAIRE

    Standfuß, Jens; Jahn, Axel; Weber, P; Neges, J.; Wischmann, S.; Höfemann, M.; Sierlinger, R.; Cretteur, L.; Veldt, T. van der; Veit, R.; Trattnig, G.; Pickett, A.; D Aiuto, F.

    2014-01-01

    The research project Reform was situated within the scope of research and technological development of steel and its utilisation. The central point of investigation was the determination of the load capability of preformed and subsequently welded parts made of high-strength steels. In order to cover a wide spectrum of automotive steel applications and with respect to the current development of modern high-strength steels, - two dual phase steels (HCT780X, HCT980X), - one trip steel (HCT690T),...

  12. Phase change predictions for liquid fuel in contact with steel structure using the heat conduction equation

    Energy Technology Data Exchange (ETDEWEB)

    Brear, D.J. [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1998-01-01

    When liquid fuel makes contact with steel structure the liquid can freeze as a crust and the structure can melt at the surface. The melting and freezing processes that occur can influence the mode of fuel freezing and hence fuel relocation. Furthermore the temperature gradients established in the fuel and steel phases determine the rate at which heat is transferred from fuel to steel. In this memo the 1-D transient heat conduction equations are applied to the case of initially liquid UO{sub 2} brought into contact with solid steel using up-to-date materials properties. The solutions predict criteria for fuel crust formation and steel melting and provide a simple algorithm to determine the interface temperature when one or both of the materials is undergoing phase change. The predicted steel melting criterion is compared with available experimental results. (author)

  13. Dual-phase CT findings of groove pancreatitis

    Energy Technology Data Exchange (ETDEWEB)

    Zaheer, Atif, E-mail: azaheer1@jhmi.edu [The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD 21231 (United States); Pancreatitis Center, Division of Gastroenterology, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, MD 21231 (United States); Haider, Maera, E-mail: mhaider3@jhmi.edu [The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD 21231 (United States); Kawamoto, Satomi, E-mail: skawamo1@jhmi.edu [The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD 21231 (United States); Hruban, Ralph H., E-mail: rhruban1@jhmi.edu [Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, the Johns Hopkins University School of Medicine, Baltimore, MD 21231 (United States); Fishman, Elliot K., E-mail: efishma1@jhmi.edu [The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD 21231 (United States)

    2014-08-15

    Purpose: Groove pancreatitis is a rare focal form of chronic pancreatitis that occurs in the pancreaticoduodenal groove between the major and minor papillae, duodenum and pancreatic head. Radiologic appearance and clinical presentation can result in suspicion of malignancy rendering pancreaticoduodenectomy inevitable. This study reports dual phase CT findings in a series of 12 patients with pathology proven groove pancreatitis. Materials and methods: Retrospective review of preoperative CT findings in 12 patients with histologically proven groove pancreatitis after pancreaticoduodenectomy. Size, location, attenuation, presence of mass or cystic components in the pancreas, groove and duodenum, calcifications, duodenal stenosis and ductal changes were recorded. Clinical data, laboratory values, endoscopic ultrasonographic and histopathological findings were collected. Results: Soft tissue thickening in the groove was seen in all patients. Pancreatic head, groove and duodenum were all involved in 75% patients. A discrete lesion in the pancreatic head was seen in half of the patients, most of which appeared hypodense on both arterial and venous phases. Cystic changes in pancreatic head were seen in 75% patients. Duodenal involvement was seen in 92% patients including wall thickening and cyst formation. The main pancreatic duct was dilated in 7 patients, with an abrupt cut off in 3 and a smooth tapering stricture in 4. Five patients had evidence of chronic pancreatitis with parenchymal calcifications. Conclusion: Presence of mass or soft tissue thickening in the groove with cystic duodenal thickening is highly suggestive of groove pancreatitis. Recognizing common radiological features may help in diagnosis and reduce suspicion of malignancy.

  14. The structural and magnetic properties of dual phase cobalt ferrite.

    Science.gov (United States)

    Gore, Shyam K; Jadhav, Santosh S; Jadhav, Vijaykumar V; Patange, S M; Naushad, Mu; Mane, Rajaram S; Kim, Kwang Ho

    2017-05-31

    The bismuth (Bi(3+))-doped cobalt ferrite nanostructures with dual phase, i.e. cubic spinel with space group Fd3m and perovskite with space group R3c, have been successfully engineered via self-ignited sol-gel combustion route. To obtain information about the phase analysis and structural parameters, like lattice constant, Rietveld refinement process is applied. The replacement of divalent Co(2+) by trivalent Bi(3+) cations have been confirmed from energy dispersive analysis of the ferrite samples. The micro-structural evolution of cobalt ferrite powders at room temperature under various Bi(3+) doping levels have been identified from the digital photoimages recorded using scanning electron microscopy. The hyperfine interactions, like isomer shift, quadrupole splitting and magnetic hyperfine fields, and cation distribution are confirmed from the Mossbauer spectra. Saturation magnetization is increased with Bi(3+)-addition up to x = 0.15 and then is decreased when x = 0.2. The coercivity is increased from 1457 to 2277 G with increasing Bi(3+)-doping level. The saturation magnetization, coercivity and remanent ratio for x = 0.15 sample is found to be the highest, indicating the potential of Bi(3+)-doping in enhancing the magnetic properties of cobalt ferrite.

  15. Precipitation process of Z-phase in 9-12%CR steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson

    2014-01-01

    Precipitation of Z-phase, Cr(V,Nb)N, is known to negatively affect creep properties of 9-12%Cr steels for power plant applications as it dissolves finely distributed MX particles, (V,Nb)N, especially in high Cr steels. As the Z-phase precipitates slowly as large particles, this causes a net drop......, allowing for a quantification of the Z-phase precipitation. The Z-phase was found to precipitate 20-50 times faster in the 12%Cr steel compared to 9%Cr steel in the temperature range 600-650°C. The transformation of MX into Z-phase was followed in a Ta containing alloy without V or Nb. In this alloy the Z...... and crystallographically into Z-phase CrTaN particles. Copyright © 2014 Electric Power Research Institute, Inc. Distributed by ASM International®. All rights reserved....

  16. On the physics and mechanics of phase transformations in TRIP-assisted multiphase steels

    OpenAIRE

    Jacques, Pascal

    1999-01-01

    The subject of this thesis is twofold: (i) to contribute to the understanding of the phase transformations and mechanical properties of TRIP-assisted multiphase steels; (ii) to show to what extent a new TRIP-assisted multiphase steel with a reduced silicon content could meet the performance requirements for high-strength formable steels. It enlightens the correlations between Processing, Microstructure and Properties. Furthermore, the different investigations carried out in this thesis will a...

  17. Dual wavelet energy approach-regression analysis for exploring steel micro structural behavior

    Science.gov (United States)

    Bettayeb, Fairouz

    2012-05-01

    Ultrasonic Ndt data are time series data decomposed in signal plus noise obtained from traveling ultrasonic waves inside a material and captured by piezoelectric sensors. The natural inhomogeneous and anisotropy character of steel made material causes high acoustic attenuation and scattering effect. This makes data interpretation highly complex for most of qualified Ndt operators. In this paper we address the non linear features of back scattered ultrasonic waves from steel plates. The structural noise data captured from the specimens, and processed by an algorithm based on wavelet energy approach, show significant insights into the relationship between backscattered noise and material microstructures. This algorithm along with correlation coefficients, residuals and interpolations calculations of processed ultrasonic data seems to be a well-adapted signal analysis tool for viewing material micro structural dimension scales. Experiments show interesting 3D interface and indicate a quasi linear signal energy distribution at micro structural level. It suggests probable incidence of microstructure acoustic signatures at different energy scales of the material phases. In conclusion multi polynomial interpolations of processed noise data exhibit an attractor shape which should involves chaos theory noise data modeling.

  18. 77 FR 50160 - Steel Wire Garment Hangers From Taiwan and Vietnam; Scheduling of the Final Phase of...

    Science.gov (United States)

    2012-08-20

    ... COMMISSION Steel Wire Garment Hangers From Taiwan and Vietnam; Scheduling of the Final Phase of... garment hangers and less- than-fair-value imports from Taiwan and Vietnam of steel wire garment hangers... merchandise as ``Steel wire garment hangers, fabricated from carbon steel wire, whether or not galvanized...

  19. 76 FR 72721 - Galvanized Steel Wire From China and Mexico; Scheduling of the Final Phase of Countervailing Duty...

    Science.gov (United States)

    2011-11-25

    ... COMMISSION Galvanized Steel Wire From China and Mexico; Scheduling of the Final Phase of Countervailing Duty... Mexico of galvanized steel wire, provided for in subheading 7217.20 of the Harmonized Tariff Schedule of... the subject merchandise as galvanized steel wire which is a cold- drawn carbon quality steel...

  20. Effect of Stable Magnetic Field on the Phase Transformation of Sr3 Steel

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-an; LIAO Dai-qiang; WU Zhan-jun

    2004-01-01

    The experimental equipment designed by the author was used to carry out quenching treatments on Sr3 steel,with and without magnet it field in different quenching mediums. The effect of steady magnetic field on the phase transformation of Sr3 steel was studied by metallographic microscope and scanning electron microscope. The result shows: the application of magnetic field can obviously increase the volume fraction of ferrite during the austenite to ferrite transformation of Sr3 steel, promote the ferrite grains refining and homogenization, and get the pearlite beam much homogeneously and much compact, when Sr3 steel is quenched in the water.

  1. Effect of Deleterious Phases on Corrosion Resistance of Duplex Stainless Steel (2205

    Directory of Open Access Journals (Sweden)

    AbdulKadar M. Godil

    2013-07-01

    Full Text Available Duplex stainless steel is a Ferritic(BCC-Austenitic(FCC steel, covers the advantages of both Austenitic and Ferritic Stainless steels. They having good mechanical and corrosion resistance properties are widely used in many industries like chemical plants, refineries for critical equipments such as pressure vessels, heatexchangers, water heaters. Major problem occurs with duplex steels when they are worked or heated above about temperature of 280°C. Detrimental phases like Sigma, Chi, Laves and Alpha prime form when the Duplex steels are treated above this temperature and they retard the properties of Duplex stainless steels. They also cause embrittlement above temperature of 475°C called “475°C embrittlement”. During welding of duplex steels, Secondary austenite also forms, which is also one of the harmful phases in duplex steels. Among all of these phases, Sigma (σ is extremely harmful to the corrosion resistance of steel. Due to these limitations duplexgrades are not used above certain temperature ranges. In this experimental work a plate of duplex grade 2205 in hot worked condition was procured from TCR Advanced Engineering Pvt. Ltd., GIDC, Vadodara. Initially chemical composition of the plate was checked with emission spectrometer, tensile test and hardness tests werecarried out for comparing with the standard data. As there was no Sigma phase detected when tested with ASTM 930 in the received sample, Sigma phase was intentionally produced by giving heat treatment in the range of 700-850°C. Sigma phases were quantified with ASTM 930 practice A, by electrolytic etching with 40% NaOH. The effect of Sigma phase on corrosion resistance was measured by ASTM G48. The pitting corrosion resistance was evaluated in terms of average pit depth and overall corrosion rate.

  2. Use of a gray level co-occurrence matrix to characterize duplex stainless steel phases microstructure

    Directory of Open Access Journals (Sweden)

    L. Zortea

    2011-04-01

    Full Text Available Duplex stainless steels are widely used in industry. This is due to their higher strength compared to austenitic steels and to their higher toughness than ferritic steels. They also have good weldability and high resistance to stress corrosion cracking.These steels are characterized by two-phase microstructures composed by almost the same level of ferrite and austenite.Duplex steel 2205 samples evaluated are: as received, cold rolled (33% and heat-treated at 800°C for 10 hours.A metallographic etching with 10% oxalic acid has been carried out to highlight the phases morphology. Some photos have been taken by SEM microscope and submitted to image analysis. The analysis carried out is based on the determination of co-occurrence matrix and on the following interpretation of appropriate indicators. Through these indicators is possible to estimate the features of images objectively.

  3. Thermodynamic calculation of phase equilibria in stainless steels

    Directory of Open Access Journals (Sweden)

    Klančnik G.

    2012-01-01

    Full Text Available In this paper two examples of thermodynamic investigation of stainless steels using both, experimental and modeling approach are described. The ferritic-austenitic duplex stainless steel and austenitic stainless steel were investigated using thermal analysis. The complex melting behavior was evident for both alloy systems. Experimentally obtained data were compared with the results of the thermodynamic calculations using the CALPHAD method. The equilibrium thermal events were also described by the calculated heat capacity. In spite of the complexity of both selected real alloy systems a relative good agreement was obtained between the thermodynamic calculations and experimental results.

  4. An asymmetric tubular ceramic-carbonate dual phase membrane for high temperature CO2 separation.

    Science.gov (United States)

    Dong, Xueliang; Ortiz Landeros, José; Lin, Y S

    2013-10-25

    For the first time, a tubular asymmetric ceramic-carbonate dual phase membrane was prepared by a centrifugal casting technique and used for high temperature CO2 separation. This membrane shows high CO2 permeation flux and permeance.

  5. A multiple-pass ring oscillator based dual-loop phase-locked loop

    Institute of Scientific and Technical Information of China (English)

    Chen Danfeng; Ren Junyan; Deng Jingjing; Li Wei; Li Ning

    2009-01-01

    A dual-loop phase-locked loop (PLL) for wideband operation is proposed. The dual-loop architecture combines a coarse-tuning loop with a fine-tuning one, enabling a wide tuning range and low voltage-controlled oscillator (VCO) gain without poisoning phase noise and reference spur suppression performance. An analysis of the phase noise and reference spur of the dual-loop PLL is emphasized. A novel multiple-pass ring VCO is designed for the dual-loop application. It utilizes both voltage-control and current-control simultaneously in the delay cell. The PLL is fabricated in Jazz 0.18-μm RF CMOS technology. The measured tuning range is from 4.2 to 5.9 GHz. It achieves a low phase noise of-99 dBc/Hz @ 1 MHz offset from a 5.5 GHz carrier.

  6. A multiple-pass ring oscillator based dual-loop phase-locked loop

    Energy Technology Data Exchange (ETDEWEB)

    Chen Danfeng; Ren Junyan; Deng Jingjing; Li Wei; Li Ning, E-mail: dfchen@fudan.edu.c [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)

    2009-10-15

    A dual-loop phase-locked loop (PLL) for wideband operation is proposed. The dual-loop architecture combines a coarse-tuning loop with a fine-tuning one, enabling a wide tuning range and low voltage-controlled oscillator (VCO) gain without poisoning phase noise and reference spur suppression performance. An analysis of the phase noise and reference spur of the dual-loop PLL is emphasized. A novel multiple-pass ring VCO is designed for the dual-loop application. It utilizes both voltage-control and current-control simultaneously in the delay cell. The PLL is fabricated in Jazz 0.18-{mu}m RF CMOS technology. The measured tuning range is from 4.2 to 5.9 GHz. It achieves a low phase noise of -99 dBc/Hz - 1 MHz offset from a 5.5 GHz carrier.

  7. STUDY ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF AUSTENITE-BAINITE STEEL

    Institute of Scientific and Technical Information of China (English)

    杨东方; 曲敬信; 邵荷生

    1994-01-01

    The microstructure characterlsties of the dual phase structure of austenite and bainite obtained in a silicon high carbon low-alloy steel, isothermally transformed, have been inverstigated and compared with that of the conventional types of microstructure. The influence of the Isothermal transformation temperatures on the microstructure and the mechanical properties of the steel has been examined. Therefore, the strengthening mechanism of the new dual phase steel with ultra-high strength has bean revealed.

  8. Review of Z phase precipitation in 9–12 wt-%Cr steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson

    2016-01-01

    For high temperature applications, 9–12 wt-%Cr steels in fossil fired power plants rely upon precipitate strengthening from (V,Nb)N MX nitrides for long term creep strength. During prolonged exposure at service temperature, another nitride precipitates: Cr(V,Nb)NZ phase. The Z phases lowly replaceMX......, eventually causing a breakdown in creep strength. The present paper reviews the Z phase and its behaviour in 9–12 wt-%Cr steels including thermodynamic modelling, crystal structure, nucleation process and precipitation rate as a function of chemical composition. The influence of Z phase precipitation upon...

  9. Extinction Ratio and Gain Optimization of Dual- Pump Degenerate-Idler Phase Sensitive Amplifiers

    DEFF Research Database (Denmark)

    Kang, Ning; Lund-Hansen, Toke; Seoane, Jorge;

    2011-01-01

    Numerical optimization of dual-pump degenerateidler phase sensitive amplifiers is performed for Al-doped and standard highly nonlinear fibers. Design considerations for operating the PSAs at an optimum combination of gain and extinction ratio are discussed.......Numerical optimization of dual-pump degenerateidler phase sensitive amplifiers is performed for Al-doped and standard highly nonlinear fibers. Design considerations for operating the PSAs at an optimum combination of gain and extinction ratio are discussed....

  10. Properties of the Measurement Phase Operator in Dual-Mode Entangle Coherent States

    Institute of Scientific and Technical Information of China (English)

    HOU Shen-Yong; YANG Kuo

    2011-01-01

    @@ A class of measurement phase operators of dual-mode is defined and their properties in a class of entangle coherent states are investigated.Numerical results indicate that the entangle coherent states display some non-classical squeezed effects.%A class of measurement phase operators of dual-mode is defined and their properties in a class of entangle coherent states are investigated. Numerical results indicate that the entangle coherent states display some non-classical squeezed effects.

  11. Structural evolution, thermomechanical recrystallization and electrochemical corrosion properties of Ni-Cu-Mg amorphous coating on mild steel fabricated by dual-anode electrolytic processing

    Science.gov (United States)

    Abdulwahab, M.; Fayomi, O. S. I.; Popoola, A. P. I.

    2016-07-01

    The electrolytic Ni-Cu based alloy coating with admixed interfacial blend of Mg have been successfully prepared on mild steel substrate by dual anode electroplating processes over a range of applied current density and dwell time. The electrocodeposition of Ni-Cu-Mg coating was investigated in the presence of other bath additives. The influence of deposition current on surface morphology, adhesion behavior, preferred crystal orientation, surface topography and electrochemical activity of Ni-Cu-Mg alloy coating on mild steel were systematically examined. The thermal stability of the developed composite materials was examined via isothermal treatment. Scanning electron microscope equipped with EDS, X-ray diffraction, Atomic force microscope, micro-hardness tester and 3 μmetrohm Potentiostat/galvanostat were used to compare untreated and isothermally treated electrocodeposited composite. The induced activity of the Ni-Cu-Mg alloy changed the surface modification and results to crystal precipitation within the structural interface by the formation of Cu, Ni2Mg3 phase. The obtained results showed that the introduction of Mg particles in the plating bath generally modified the surface and brings an increase in the hardness and corrosion resistance of Ni-Cu-Mg layers fabricated. Equally, isothermally treated composites demonstrated an improved properties indicating 45% increase in the micro-hardness and 79.6% corrosion resistance which further showed that the developed composite is thermally stable.

  12. Widely tunable microwave phase shifter based on silicon-on-insulator dual-microring resonator

    DEFF Research Database (Denmark)

    Pu, Minhao; Liu, Liu; Xue, Weiqi;

    2010-01-01

    We propose and demonstrate tunable microwave phase shifters based on electrically tunable silicon-on-insulator microring resonators. The phase-shifting range and the RF-power variation are analyzed. A maximum phase-shifting range of 0~600° is achieved by utilizing a dual-microring resonator...

  13. Two-Phase Master Sintering Curve for 17-4 PH Stainless Steel

    Science.gov (United States)

    Jung, Im Doo; Ha, Sangyul; Park, Seong Jin; Blaine, Deborah C.; Bollina, Ravi; German, Randall M.

    2016-11-01

    The sintering behavior of 17-4 PH stainless steel has been efficiently characterized by a two-phase master sintering curve model (MSC). The activation energy for the sintering of gas-atomized and water-atomized 17-4 PH powders is derived using the mean residual method, and the relative density of both powders is well predicted by the two-phase MSC model. The average error between dilatometry data and MSC model has been reduced by 68 pct for gas-atomized powder and by 45 pct for water-atomized powder through the consideration of phase transformation of 17-4 PH in MSC model. The effect of δ-ferrite is considered in the two-phase MSC model, leading to excellent explanation of the sintering behavior for 17-4 PH stainless steel. The suggested model is useful in predicting the densification and phase change phenomenon during sintering of 17-4 PH stainless steel.

  14. In-Situ Observation of Growth Behavior of Niobium Carbide during Dual-Phase Rapid Solidification of SUS347H

    Science.gov (United States)

    Yonemura, Mitsuharu; Osuki, Takahiro; Hirata, Hiroyuki; Ogawa, Kazuhiro

    2008-01-01

    In order to improve solidification cracking susceptibility, the crystallization of a heterophase such as the niobium carbide in the brittle temperature range is one of the effective techniques. In such a system, not only the growth behavior of dendrites during the rapid cooling but also the crystallization behavior of heterophase is very important. Therefore, diffraction patterns of a dual-phase mode Nb-bearing stainless steel during rapid cooling were investigated by in-situ two-dimensional time-resolved X-ray diffraction for the first time in order to reveal the microstructure formation. We discuss the growth behavior of dendrites with crystallization of niobium carbides. Subsequently, the niobium carbide formed epitaxially to the dendrite of the preferred in-plane orientation, having a small distorted orientation. With undercooling of several degree Celsius, the coherent growth on the δ-ferrite was stable for niobium carbide.

  15. Phase transformations evaluation on a UNS S31803 duplex stainless steel based on nondestructive testing

    Energy Technology Data Exchange (ETDEWEB)

    Macedo Silva, Edgard de, E-mail: edgard@cefetpb.edu.br [Centro federal de Educacao Tecnologica da Paraiba (CEFET PB), Area da Industria, Avenida 1o de Maio, 720 - 58015-430 - Joao Pessoa/PB (Brazil); Costa de Albuquerque, Victor Hugo, E-mail: victor.albuquerque@fe.up.pt [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Cidade Universitaria, S/N - 58059-900 - Joao Pessoa/PB (Brazil); Pereira Leite, Josinaldo, E-mail: josinaldo@ct.ufpb.br [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Cidade Universitaria, S/N - 58059-900 - Joao Pessoa/PB (Brazil); Gomes Varela, Antonio Carlos, E-mail: varela@cefetpb.edu.br [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Cidade Universitaria, S/N - 58059-900 - Joao Pessoa/PB (Brazil); Pinho de Moura, Elineudo, E-mail: elineudo@pq.cnpq.br [Universidade Federal do Ceara (UFC), Departamento de Engenharia Metalurgica e de Materiais, Campus do Pici, Bloco 715, 60455-760 - Fortaleza/CE (Brazil); Tavares, Joao Manuel R.S., E-mail: tavares@fe.up.pt [Faculdade de Engenharia da Universidade do Porto (FEUP), Departamento de Engenharia Mecanica e Gestao Industrial (DEMEGI)/Instituto de Engenharia Mecanica e Gestao Industrial - INEGI, Rua Dr. Roberto Frias, s/n, 4200-465 Porto (Portugal)

    2009-08-15

    Duplex stainless steel presents special mechanical properties such as, for example, mechanical and corrosion strength, becoming competitive in relation to the other types of stainless steel. One of the great problems of duplex stainless steel microstructural changes study is related to embrittlement above 300 deg. C, with the precipitation of the {alpha}' phase occurring over the ferritic microstructure. Aiming to characterise embrittlement of duplex stainless steel, hardening kinetics, from 425 to 475 deg. C, was analysed through the speed of sound, Charpy impact energy, X-ray diffraction, hardness and microscopy parameters. The presence of two hardening stages, detected through the speed of sound, was observed, one being of brittle characteristic and the other ductile. Moreover, the speed of sound showed a direct correlation with the material's hardness. Thus, it is concluded that the speed of sound is a promising nondestructive parameter to follow-up embrittlement in duplex stainless steel.

  16. Formation and coalescence of strain localized regions in ferrite phase of DP600 steels under uniaxial tensile deformation

    Energy Technology Data Exchange (ETDEWEB)

    Alaie, A., E-mail: amir_alaie@yahoo.com [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Kadkhodapour, J. [Department of Mechanical Engineering, Shahid Rajaee Teacher Training University, Tehran (Iran, Islamic Republic of); Institute for Materials Testing, Materials Science and Strength of Materials (IMWF), University of Stuttgart, Stuttgart (Germany); Ziaei Rad, S. [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Asadi Asadabad, M. [Materials Research School, Isfahan (Iran, Islamic Republic of); Schmauder, S. [Institute for Materials Testing, Materials Science and Strength of Materials (IMWF), University of Stuttgart, Stuttgart (Germany)

    2015-01-19

    In this study the key factors in the creation and coalescence of strain localization regions in dual-phase steels were investigated. An in-situ tensile setup was used to follow the microscopic deformation of ferrite phase inside the microstructure of DP600 steel. The test was continued until the specimen was very close to final failure. The captured scanning electron microscopy (SEM) micrographs enabled us to directly observe the evolution of deformation bands as a contour of strain distribution in the ferrite matrix. The image processing method was used to quantify the ferrite microscopic strains; the obtained strain maps were superimposed onto the SEM micrographs. The results revealed important deformational characteristics of the microstructure at the microscopic level. It was observed that despite the formation of slip bands inside the large grains during the early stages of deformation, the large ferrite grains did not contribute to the formation of high-strain bands until the final stages of severe necking. The behavior of voids and initial defects inside the localization bands was also studied. In the final stages of deformation, cracks were observed to preferentially propagate in the direction of local deformation bands and to coalescence with each other to form the final failure lines in the microstructure. It was observed that in the final stages of deformation, the defects or voids outside the deformation bands do not contribute to the final failure mechanisms and could be considered to be of minor importance.

  17. 360° tunable microwave phase shifter based on silicon-on-insulator dual-microring resonator

    DEFF Research Database (Denmark)

    Pu, Minhao; Xue, Weiqi; Liu, Liu;

    2010-01-01

    We demonstrate tunable microwave phase shifters based on electrically tunable silicon-on-insulator dual-microring resonators. A quasi-linear phase shift of 360° with ~2dB radio frequency power variation at a microwave frequency of 40GHz is obtained......We demonstrate tunable microwave phase shifters based on electrically tunable silicon-on-insulator dual-microring resonators. A quasi-linear phase shift of 360° with ~2dB radio frequency power variation at a microwave frequency of 40GHz is obtained...

  18. Kinetics of Z-Phase Precipitation in 9 to 12 pct Cr Steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Nunzio, Paolo Emilio di; Hald, John

    2013-01-01

    The Z-phase nitride is seen as a detrimental phase in 9 to 12 pct Cr steels as it is in competition with the beneficial MX particles. Two model steels, with 9 pct Cr and 12 pct Cr content, respectively, were designed to study the effect of Cr on Z-phase precipitation kinetics. The steels were...... isothermally aged at 873 K, 923 K, and 973 K (600 °C, 650 °C, and 700 °C) for up to 30,000 hours in order for Z-phase to replace MX. X-ray diffraction (XRD) analysis of extracted precipitates was used to quantitatively follow the evolution of the nitrides population. It was found that the 12 pct Cr steel...... precipitated Z-phase 20 to 50 times faster than the 9 pct Cr steel. Transmission electron microscopy (TEM) was applied to follow the Z-phase precipitation, using energy-dispersive X-ray spectroscopy (EDS) line scans and atomic resolution imaging. © The Minerals, Metals & Materials Society and ASM International...

  19. Kinetics of Z-Phase Precipitation in 9 to 12 pct Cr Steels

    Science.gov (United States)

    Danielsen, Hilmar K.; di Nunzio, Paolo Emilio; Hald, John

    2013-05-01

    The Z-phase nitride is seen as a detrimental phase in 9 to 12 pct Cr steels as it is in competition with the beneficial MX particles. Two model steels, with 9 pct Cr and 12 pct Cr content, respectively, were designed to study the effect of Cr on Z-phase precipitation kinetics. The steels were isothermally aged at 873 K, 923 K, and 973 K (600 °C, 650 °C, and 700 °C) for up to 30,000 hours in order for Z-phase to replace MX. X-ray diffraction (XRD) analysis of extracted precipitates was used to quantitatively follow the evolution of the nitrides population. It was found that the 12 pct Cr steel precipitated Z-phase 20 to 50 times faster than the 9 pct Cr steel. Transmission electron microscopy (TEM) was applied to follow the Z-phase precipitation, using energy-dispersive X-ray spectroscopy (EDS) line scans and atomic resolution imaging.

  20. Magnetic detection of sigma phase in duplex stainless steel UNS S31803

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, S.S.M., E-mail: ssmtavares@terra.com.b [Universidade Federal Fluminense, Departamento de Engenharia Mecanica, PGMEC, Rua Passo da Patria, 156, CEP 24210-240, Niteroi (Brazil); Pardal, J.M.; Guerreiro, J.L. [Universidade Federal Fluminense, Departamento de Engenharia Mecanica, PGMEC, Rua Passo da Patria, 156, CEP 24210-240, Niteroi (Brazil); Gomes, A.M. [Universidade Federal do Rio de Janeiro, Instituto de Fisica (Brazil); Silva, M.R. da [Universidade Federal de Itajuba, Instituto de Ciencias (Brazil)

    2010-09-15

    Duplex stainless steels are high strength and corrosion resistant steels extensively used in the chemical and petrochemical industry. The best mechanical properties and corrosion resistance are obtained with a microstructure composed by equal parts of ferrite and austenite and free from tertiary phases. Sigma phase is one of these deleterious tertiary phases. In the present work different amounts of sigma phase were precipitated by heat treatments in a UNS S31803 stainless steel. Some specimens were cold rolled before sigma phase precipitation in order to evaluate the effect of deformation on the magnetic measurements. The amount of sigma phase was precisely determined by microscopy and image analysis for each heat treatment condition. The effects of sigma phase on the steel properties were investigated, confirming the detrimental effects of very small percentages on corrosion resistance and toughness. Two magnetic methods were used to detect sigma phase: magnetization saturation measurements in a Vibrating Sample Magnetometer and ferritoscope testing. Both methods were found to be sensitive to small percentages of sigma phase in the microstructure.

  1. Phase equilibria in the UO 2-austenitic steel system up to 3000°C

    Science.gov (United States)

    Kleykamp, Heiko

    1997-08-01

    The pseudobinary UO 2-austenitic steel system was investigated by DTA up to 1500°C, by isothermal annealing up to 2000°C, by induction heating up to 2850°C and by arc melting up to about 3000°C. The system is characterized by a degenerate eutectic at 1433°C on the steel side and a monotectic at 2830°C and about 1 mol% steel. The maximum solubility of steel in solid U0 2 is 0.6 mol%, that in liquid U0 2 at 3000°C is about 4 mol%. U0 2 and steel form (Fe, Mn, Cr) 2O 3 precipitates between 1300 and 2600°C as U02 becomes hypostoichiometric. Liquid steel is stabilized to higher temperatures above its boiling point at 2790°C by dissolution of uranium and decomposes peritectically to liquid UO 2-χ and gas at estimated 3200°C. The critical data of the single-phase U0 2-steel melt based on the application of the Redlich-Kister model are Tc = 4900°C, Pc = 300 bar and χ c, steel = 0.41.

  2. Phase transformation studies af a low alloy steel in the (α + γ phase region

    Directory of Open Access Journals (Sweden)

    Kenneth Kanayoa Alaneme

    2010-03-01

    Full Text Available This research work describes a thermo mechanical investigation of a low alloy steel treated in the (α + γ phase region. The aim is to develop a high tensile, ductile microstructure that could have a wide range of engineering applications. Recent advances in the area of precipitation, recrystallization mechanisms, and α / γ transformations provide strong background to this study. In a preliminary heat treatment, various microstructures (normalized and 450 °C tempered martensite structure were produced and deformed to varying degrees. Subsequently, these microstructures were subjected to various intercritical temperatures (740 and 760 °C for various times and a very high cooling rate. Light (optical microscopic investigations were carried out to study the ensuing microstructures. Mechanical testing results (tensile and hardness values were used to characterize the structures obtained. On analysis of the result, it was observed that well defined micro-duplex structures of ferritic and martensitic nature, possessing good combinations of strength and ductility were obtained.

  3. Quantification of Laves Phase Particle Size in 9CrW Steel

    DEFF Research Database (Denmark)

    Korcakova, Leona; Hald, John; Somers, Marcel A.J.

    2001-01-01

    Tungsten-alloyed martensic 9Cr steels are applied for streamlines of advanced power plants because of their superior creep performance. Tungsten, as the main new alloying element, induces precipitation of intermetallic Laves phase during long-term exposure at service temperatures around 600 C....... The growth and coarsening of Laves phase was investigated for the martensitic 9CrW steel P92 after aging and after creep testing at 600 or 650 C for times up to 59,000 h. For measurement of the size of Laves phase particles, field emission gun scanning electron microscopy (FEGSEM) was used along with image...

  4. Review of Z phase precipitation in 9–12 wt-%Cr steels

    OpenAIRE

    Danielsen, Hilmar Kjartansson

    2016-01-01

    For high temperature applications, 9–12 wt-%Cr steels in fossil fired power plants rely upon precipitate strengthening from (V,Nb)N MX nitrides for long term creep strength. During prolonged exposure at service temperature, another nitride precipitates: Cr(V,Nb)NZ phase. The Z phases lowly replaceMX, eventually causing a breakdown in creep strength. The present paper reviews the Z phase and its behaviour in 9–12 wt-%Cr steels including thermodynamic modelling, crystal structure, nucleation pr...

  5. Review of Z phase precipitation in 9–12 wt-%Cr steels

    OpenAIRE

    Danielsen, Hilmar Kjartansson

    2016-01-01

    For high temperature applications, 9–12 wt-%Cr steels in fossil fired power plants rely upon precipitate strengthening from (V,Nb)N MX nitrides for long term creep strength. During prolonged exposure at service temperature, another nitride precipitates: Cr(V,Nb)NZ phase. The Z phases lowly replaceMX, eventually causing a breakdown in creep strength. The present paper reviews the Z phase and its behaviour in 9–12 wt-%Cr steels including thermodynamic modelling, crystal structure, nucleation pr...

  6. Z phase stability in AISI 316LN + Nb austenitic steels during creep at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Vodarek, Vlastimil [Technical Univ. Ostrava (Czech Republic)

    2010-07-01

    The creep resistance of austenitic CrNi(Mo) steels strongly depends on microstructural stability during creep exposure. Nitrogen additions to CrNi(Mo) austenitic steels can significantly improve the creep strength. One of the most successful methods of improving the long-term creep resistance of austenitic steels is based on increasing the extent of precipitation strengthening during creep exposure. The role of precipitates in the achievements of good creep properties has been extensively studied for a long time. Although many minor phases are now well documented there are still contractions and missing thermodynamic data about some minor phases. This contribution deals with results of microstructural studies on the minor phase evolution in wrought AISI 316LN niobium stabilised steels during long-term creep exposure at 650 C. Microstructural investigations were carried out on specimens taken from both heads and gauge lengths of ruptured test-pieces by means of optical metallography, transmission and scanning electron microscopy. The attention has been paid to evaluation of thermodynamic and dimensional stability of Z phase and other nitrogen bearing minor phases. Only two nitrogen-bearing minor phases formed in the casts investigated: Z phase and M{sub 6}X. The dimensional stability of Z phase particles was very high. (orig.)

  7. Z phase stability in AISI 316LN + Nb austenitic steels during creep at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Vodarek, Vlastimil [Technical Univ. Ostrava (Czech Republic)

    2010-07-01

    The creep resistance of austenitic CrNi(Mo) steels strongly depends on microstructural stability during creep exposure. Nitrogen additions to CrNi(Mo) austenitic steels can significantly improve the creep strength. One of the most successful methods of improving the long-term creep resistance of austenitic steels is based on increasing the extent of precipitation strengthening during creep exposure. The role of precipitates in the achievements of good creep properties has been extensively studied for a long time. Although many minor phases are now well documented there are still contractions and missing thermodynamic data about some minor phases. This contribution deals with results of microstructural studies on the minor phase evolution in wrought AISI 316LN niobium stabilised steels during long-term creep exposure at 650 C. Microstructural investigations were carried out on specimens taken from both heads and gauge lengths of ruptured test-pieces by means of optical metallography, transmission and scanning electron microscopy. The attention has been paid to evaluation of thermodynamic and dimensional stability of Z phase and other nitrogen bearing minor phases. Only two nitrogen-bearing minor phases formed in the casts investigated: Z phase and M{sub 6}X. The dimensional stability of Z phase particles was very high. (orig.)

  8. Dilatometric investigations of phase transformations at heating and cooling of hardened, unalloyed, high-carbon steels

    Directory of Open Access Journals (Sweden)

    J. Pacyna

    2011-05-01

    Full Text Available Purpose: The reason for writing this paper was to describe the kinetics of phase transformations during continuous heating from hardened state and subsequent cooling of unalloyed high carbon steel.Design/methodology/approach: Dilatometric investigations were performed using a DT 1000 dilatometer of a French company Adamel. Samples after quenching and quenching and sub-quenching in liquid nitrogen (-196 °C were heated up 700 °C at the rate of 0.05 °C/s and subsequent cooled to room temperature at the rate of 0.05 °C/s.Findings: Regardless of heating the hardened high-carbon steel to 700 °C, a small fraction of the retained austenite remained in its structure, and was changing into fresh martensite only during cooling in the temperature range: 280°C-170°C.Research limitations/implications: Schematic presentation of the differential curve of tempering of the hardened high-carbon, unalloyed steel illustrating the phase transformations occurring during heating from hardened state.Practical implications: An observation, that a small fraction of the retained austenite remained in the structure of tempered high-carbon steel, indicates that even unalloyed steel should be tempered two times.Originality/value: Detailed descriptions of kinetics phase transformations during heating from hardened state of unalloyed high carbon steel.

  9. DEFORMATION MEASUREMENT USING DUAL-FREQUENCY PROJECTION GRATING PHASE-SHIFT PROFILOMETRY

    Institute of Scientific and Technical Information of China (English)

    Yanming Chen; Yuming He; Eryi Hu; Hongmao Zhu

    2008-01-01

    phase ambiguity problem is very important in phase measurement when a deformed object has a large out of plane displacement. The dual-frequency projection grating phaseshifting profilometry (PSP) can be used to solve such an issue. In the measurement, two properchosen frequency gratings are utilized to synthesize an equivalent wavelength grating which ensures the computed phase in a principal phase range. Thus, the error caused by the phase unwrapping process with the conventional phase reconstruct algorithm can be eliminated. Finally, experimental result of a specimen with large plastic deformation is given to prove that the proposed method is effective to handle the phase discontinuity.

  10. New Space Vector Selection Scheme for VSI Supplied Dual Three-Phase Induction Machine

    Directory of Open Access Journals (Sweden)

    MILICEVIC, D.

    2013-02-01

    Full Text Available This paper presents a novel space vector selection scheme applicable for the control of dual three-phase induction motor drives supplied from a six-phase voltage source inverter (VSI. The vector selection method is based on the vector space decomposition technique (VSD. Unique vector selection pattern simplifies problems related to complicated implementation of standard VSD in commercially available digital signals processors (DSP. The proposed vector selection scheme is verified through a theoretical analysis, computer simulations and practical experimental results conducted on a dual three-phase test rig prototype with control algorithm implemented in Texas Instrument?s TMS320F2808 DSP.

  11. Design and Synthesis of a Dual Linker for Solid Phase Synthesis of Oleanolic Acid Derivatives

    Directory of Open Access Journals (Sweden)

    Shaorong Wang

    2011-06-01

    Full Text Available A hydrophilic amino-terminated poly(ethylene glycol-type dual linker for solid phase synthesis of oleanolic acid derivatives using trityl chloride resin was designed and synthesized for the first time. Model reactions in both liquid and solid phase were performed to show the feasibility of its selective cleavage at two different sites. The biological assay results indicated that the long and flexible alkyl ether functionality in the linker is less likely to be critical for the binding event. Following the successful solid-phase synthesis of model compounds, the potential of this dual linker in reaction monitoring and target identification is deemed worthy of further study.

  12. DUAL THREE-PHASE ADJUSTABLE SPEED DRIVE WITH SYNCHRONIZED SPACE-VECTOR MODULATION

    Directory of Open Access Journals (Sweden)

    Oleschuk V.I.

    2008-04-01

    Full Text Available Split-phase symmetrical motor drive on the base of two voltage source inverters, controlled by algorithms of synchronized pulse width modulation (PWM, has been investigated. Simulation results are presented for dual three-phase power conversion systems with continuous, discontinuous and combined versions of synchronized PWM.

  13. Creep properties of aged duplex stainless steels containing [sigma] phase

    Energy Technology Data Exchange (ETDEWEB)

    Shek, C.H.; Wong, K.W.; Lai, J.K.L. (City Univ. of Hong Kong, Kowloon (Hong Kong). Dept. of Physics and Materials Science); Li, D.J. (Department of Materials Engineering, Dalian University of Technology, Dalian 116 024 (China))

    1999-06-30

    The creep properties of a cast of duplex stainless steel were characterized at temperatures 550-800 C under different loading conditions. For fully aged specimens containing [sigma], the stress exponent for creep was close to 3 and the activation energy was 281[+-]9 kJ mol[sup -1]. The results suggested that the creep mechanism in the samples in this investigation was controlled by dislocation movement. Extensive [sigma]/[gamma][sub 2] interfaces introduced during ageing improved the creep resistance of the material and related to a reduction of the creep rate in Stage II creep and an increase in the creep rupture strength of the material. Microstructural studies revealed the dependence of the creep properties on the morphology of the microstructure. Among the aged specimens containing [sigma], the creep strength and ductility were higher for specimens having larger [gamma] grain thickness measured on the longitudinal plane. This characteristic was related to the crack propagation and interconnection of voids within [gamma] matrix during tertiary creep. With appropriate solution treatment, the creep strength of [sigma]-containing steels can be improved to a value exceeding that of type 316 steels. (orig.) 14 refs.

  14. Final Report Auto/Steel Partnership Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Cady, C.M.; Chen, S.R.; Gray, G.T. III

    1999-06-09

    This is the final report in which effects of strain-rate, temperature, and stress-state on the yield stress and the strain hardening behavior of many common steels used in automobile construction were investigated. The yield and flow stresses were found to exhibit very high rate sensitivities for most of the steels while the hardening rates were found to be insensitive to strain rate and temperature at lower temperatures or at higher strain rates. This behavior is consistent with the observation that overcoming the intrinsic Peierls stress is shown to be the rate-controlling mechanism in these materials at low temperatures. The dependence of the yield stress on temperature and strain rate was found to decrease while the strain hardening rate increased. The Mechanical Threshold Stress (MTS) model was adopted to model the stress-strain behavior of the steels. Parameters for the constitutive relations were derived for the MTS model and also for the Johnson-Cook (JC) and the Zerilli-Armstrong (ZA) models. The results of this study substantiate the applicability of these models for describing the high strain-rate deformation of these materials. The JC and ZA models, however, due to their use of a power strain hardening law were found to yield constitutive relations for the materials which are strongly dependent on the range of strains for which the models were optimized.

  15. Structural and phase transformations in Hadfield steel upon frictional loading in liquid nitrogen

    Science.gov (United States)

    Korshunov, L. G.; Sagaradze, V. V.; Chernenko, N. L.

    2016-08-01

    Structural transformations that occur in 110G13 steel (Hadfield) upon sliding friction in liquid nitrogen (-196°C) have been investigated by metallographic, electron-microscopic, and X-ray diffraction methods. The frictional action was performed through the reciprocating sliding of a cylindrical indenter of quenched 110G13 steel over a plate of the studied steel. A like friction pair was immersed into a bath with liquid nitrogen. It has been shown that the Hadfield steel quenched from 1100°C under the given temperature conditions of frictional loading retains the austenitic structure completely. The frictional action forms in a surface layer up to 10 μm thick the nanocrystalline structure with austenite grains 10-50 nm in size and a hardness 6 GPa. Upon subsequent low-temperature friction, the tempering of steel at 400°C (3 h) and at 600°C (5 min and 5 h) brings about the formation of a large amount (tens of vol %) of ɛ (hcp) martensite in steel. The formation of this phase under friction is supposedly a consequence of the reduction in the stacking fault energy of Hadfield steel, which is achieved due to the combined action of the following factors: low-temperature cooling, a decrease in the carbon content in the austenite upon tempering, and the presence of high compressive stresses in the friction-contact zone.

  16. Conversion of MX Nitrides to Modified Z-Phase in 9-12%Cr Ferritic Steels

    DEFF Research Database (Denmark)

    Cipolla, Leonardo

    , crystal structure, chemical composition and equivalent diameter of precipitates were assessed over times and temperatures. The mechanism of Z-phase formation was identified in the model alloys; hybrid MX/Z particles were found as mid-stage phases of this conversion. The key-role of niobium as accelerator....... Indeed the fast conversion of finely distributed MX nitrides, which highly promote creep strengthening, to larger and thermodynamically more stable modified Z-phase, Cr(V,Nb)N, led to an unforeseen drop of creep resistance of 12%Cr steels. Since chromium content was confirmed to be the main driving force...... for Z-phase formation, this explains why 12%Cr steels (i.e. P122, VM12, NF12) suffer from fast and abundant Z-phase precipitation, while 9%Cr steels (i.e. Grades 91, 92, 911) do not. In this thesis the role of vanadium and niobium nitrides in the formation of Z-phase in 9-12%Cr steels is investigated...

  17. Precipitate phases in normalized and tempered ferritic/martensitic steel P92

    Science.gov (United States)

    Shen, Yinzhong; Liu, Huan; Shang, Zhongxia; Xu, Zhiqiang

    2015-10-01

    Ferritic/martensitic steel P92 is a promising candidate for cladding and duct applications in Sodium-Cooled Fast Reactor. The precipitate phases of the P92 steel normalized at 1323 K (1050 °C) for 30 min and tempered at 1038 K (765 °C) for 1 h have been investigated using transmission electron microscopes. Four types of phases consisting of M23C6, MX, M2X and sigma-FeCr were identified in the steel. MX phases consist of Nb-rich M(C,N) carbonitride, Nb-rich MC carbide, V-rich M(C,N) carbonitride, V-rich MC carbide, V-rich MN nitride, and complex MC carbides with Nb-rich MC core and V-rich MC wings. M2X phases consist of Cr-rich M2(C,N) carbonitride, Cr-rich M2C carbide and M2N nitride. Sigma-FeCr has a simple tetragonal lattice and a typical chemical formula of Fe0.45Cr0.45W0.1. M23C6 and MX are the dominant phases, while the sigma-FeCr has the lowest content. The formation of sigma-FeCr and M2X phases in the steel is also discussed.

  18. Precipitation Effect on Mechanical Properties and Phase Stability of High Manganese Steel

    Science.gov (United States)

    Bae, Cheoljun; Kim, Rosa; Lee, Un-Hae; Kim, Jongryoul

    2017-09-01

    High manganese (Mn) steels are attractive for automotive applications due to their excellent tensile strength and superior elongation. However, the relatively low yield strength of Mn steels compared to other advanced high-strength steels is a critical problem limiting their use in structural parts. In order to increase the yield strength, the precipitation hardening effect of Mn steels was investigated by the addition of carbide-forming elements. Changes in the austenite phase stability were also evaluated in terms of stacking fault energy (SFE). As a result, fine V(C,N) precipitates were found to increase the yield strength effectively but to lower the SFE by the consumption of matrix carbons. For achieving precipitation hardening without sacrificing austenite stability, the soluble carbon content was discussed.

  19. Abnormal grain growth in Eurofer-97 steel in the ferrite phase field

    Science.gov (United States)

    Oliveira, V. B.; Sandim, H. R. Z.; Raabe, D.

    2017-03-01

    Reduced-activation ferritic-martensitic (RAFM) Eurofer-97 steel is a candidate material for structural applications in future fusion reactors. Depending on the amount of prior cold rolling strain and annealing temperature, important solid-state softening reactions such as recovery, recrystallization, and grain growth occur. Eurofer-97 steel was cold rolled up to 70, 80 and 90% reductions in thickness and annealed in the ferrite phase field (below ≈ 800 °C). Changes in microstructure, micro-, and mesotexture were followed by orientation mappings provided by electron backscatter diffraction (EBSD). Eurofer-97 steel undergoes abnormal grain growth above 650 °C and this solid-state reaction seems to be closely related to the high mobility of a few special grain boundaries that overcome pinning effects caused by fine particles. This solid-state reaction promotes important changes in the microstructure and microtexture of this steel. Abnormal grain growth kinetics for each condition was determined by means of quantitative metallography.

  20. Physical Metallurgy of Modern Creep-Resistant Steel for Steam Power Plants: Microstructure and Phase Transformations

    Directory of Open Access Journals (Sweden)

    V. C. Igwemezie

    2016-01-01

    Full Text Available The fact that the microstructure of steel depends on its composition and the heat treatment given to it has been heavily exploited in the design of steel for power plant applications. To obtain a steel that can function at the higher temperature where power plants operate without failure for extended life, heat treatment is needed to produce fine and highly stable dispersion of carbides, nitrides, and intermetallic compounds in the microstructure of the material. A significant contribution also comes from solid solution strengthening by substitutional solutes. We review here various types of phases, microstructures, functions, and interacting effects of the various alloying elements in the design of steel for modern power plant application.

  1. Effects of Alloying Elements on the Concentration Profile of Equilibrium Phases in Transformation Induced Plasticity Steel

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    With the two sublattices model, equilibrium compositions of ferrite (α) and austenite (γ) phases, as well as thevolume percent of austenite (γ) in different TRIP steels are calculated. Concentration profiles of carbon, manganese,aluminum and silicon in these steels are also estimated under the lattice fixed frame of reference so as to identifyif the equilibrium state is obtained. Through the comparison between the profiles after different time diffusion, thedistribution of elements in phases is exhibited and the complex effect due to the mutual interaction of the elementson diffusion is discussed.

  2. Phase Field Simulation for Grains Evolution of 17-4PH Steel During Cyclic Heat Treatment

    Institute of Scientific and Technical Information of China (English)

    Yuan YOU; Mufu YAN; Chengsong ZHANG

    2013-01-01

    A phase field model is developed to simulate the grain evolution of 17-4PH steel during cyclic heat treatment (CHT).Our simulations successfully reproduce the grain morphologies of every CHT.In the process of every CHT,phase transformation recrystallization happens.The recrystallized grains appear mainly on the original grain boundaries.The average grain size of 13.2 μm obtained by 1040 ℃C×1 h solution treatment for this experimental steel can be refined to 2.2 μm after five CHT's.Furthermore,the effects of phenomenological parameters in our model are discussed.

  3. Precipitation of Nanosized MX at Coherent Cu-Rich Phases in Super304H Austenitic Steel

    Science.gov (United States)

    Ou, Ping; Xing, Hui; Sun, Jian

    2015-01-01

    The present investigation of transmission electron microscopy reports the precipitation of nanosized and cubical-shaped incoherent Nb-rich MX at the coherent Cu-rich phases in the austenitic matrix of the Super304H steel. In addition, the nanosized Nb-rich MX phases were often observed to precipitate on dislocations during creep. It is concluded that the dense incoherent Nb-rich MX and coherent Cu-rich precipitates with a nanosized diameter contribute excellent creep resistance in the steel.

  4. Recent Progress in High Strength Low Carbon Steels

    Directory of Open Access Journals (Sweden)

    Zrník J.

    2006-01-01

    Full Text Available Advanced High Strength (AHS steels, among them especially Dual Phase (DP steels, Transformation Induced Plasticity (TRIP steels, Complex Phase (CP steels, Partially Martensite (PM steels, feature promising results in the field. Their extraordinary mechanical properties can be tailored and adjusted by alloying and processing. The introduction of steels with a microstructure consisting at least of two different components has led to the enlargement of the strength level without a deterioration of ductility. Furthermore, the development of ultra fine-grained AHS steels and their service performance are reviewed and new techniques are introduced. Various projects have been devoted to develop new materials for flat and long steel products for structural applications. The main stream line is High Strength, in order to match the weight lightening requirements that concern the whole class of load bearing structures and/or steel components and one of the most investigated topics is grain refinement.

  5. Commissioning and Charge Readout Calibration of a 5 Ton Dual Phase Liquid Argon TPC

    CERN Document Server

    AUTHOR|(CDS)2098555

    Dual phase time projection chambers with amplification of ionization electrons provide a novel technique for measuring and analyzing rare events with excellent spatial resolution and great calorimetric properties. This thesis describes the commissioning of the WA105 3 x 1 x 1 m3 dual phase liquid argon detector, built to demonstrate the performance of this kind of detector on large scales in order to determine the viability of giant dual phase time projection chambers in long baseline neutrino oscillation experiments. The properties of the insulation and the main tank vessel are described and analyzed, such as the pressure, temperature and argon purity requirements during operation in order to guarantee stable conditions and good event tracking. As signals are induced due to electrons from ionizing radiation, crosstalk is caused by capacitive couplings between strips of the charge readout plane and in the electronics of the data acquisition. These induced signals are studied and compared to capacitance and pu...

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

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y., E-mail: yangying@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Busby, J.T. [Fusion and Materials for Nuclear Systems Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2014-05-01

    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.

  7. Effects of Manganese Content on Solidification Structures, Thermal Properties, and Phase Transformation Characteristics in Fe-Mn-C Steels

    Science.gov (United States)

    Yang, Jian; Wang, Yu-Nan; Ruan, Xiao-Ming; Wang, Rui-Zhi; Zhu, Kai; Fan, Zheng-Jie; Wang, Ying-Chun; Li, Cheng-Bin; Jiang, Xiao-Fang

    2015-02-01

    The solidification structures and the thermal properties of Fe-Mn-C steel ingots containing different manganese contents have been investigated and the phase transformation characteristics have been revealed by Thermo-Calc to assist development of the continuous casting technology of Fe-Mn-C steels. The results show that the thermal conductivity of the 0Mn steel is higher than that of the 3Mn steel. The thermal conductivity of the 6Mn steel is the lowest in the three kinds of steels below 1023 K (750 °C) and the highest above 1173 K (900 °C). The 0Mn steel has the highest value of the proportion of equiaxed grain zone area in the three kinds of steels, whereas the 3Mn steel has the lowest value of it in the steels. Manganese has the effect of promoting the coarsening of grains. The microstructure is martensite and a little retained austenite (3.8 mass pct) in the 6Mn steel, whereas the microstructure is bainite in the 3Mn steel. The 0Mn steel is characterized by ferrite and pearlite. The mean thermal expansion coefficients of the steels are in the range from 1.0 × 10-5 to 1.6 × 10-5 K-1, and the determinations of mold tapers of the 6Mn and 3Mn steels can refer to low-carbon steel. Using RA steel is 873 K to 1073 K (600 °C to 800 °C), whereas those of the 3Mn steel and the 0Mn steel are 873 K to 1123 K (600 °C to 850 °C) and 873 K to 1173 K (600 °C to 900 °C), respectively. In the 6Mn and 3Mn steels, the deformation-induced ferrite (DIF) forms in sufficient quantities cause the recovery of the ductility at the low temperature end. However, since low strains are present when straightening, sufficient quantities of DIF cannot be formed. Thus, the ductility of the 6Mn and 3Mn steels cannot be improved during the continuous casting process. Manganese has the effect of enlarging the austenite phase region and reducing the δ-ferrite phase region and α-ferrite phase region.

  8. Bake hardening behavior of TRIP and DP steels

    Institute of Scientific and Technical Information of China (English)

    Jicheng Zhang; Renyu Fu; Mei Zhang; Rendong Liu; Xicheng Wei; Lin Li

    2008-01-01

    The bake hardening (BH) behavior of transformation-induced plasticity (TRIP) and dual-phase (DP) steels after different prestrains was studied. The experimental results indicate that TRIP steel exhibits good BH ability while DP steel does not, and prestrain displays a strong effect on the BH values of both steels. The comparison of microstructures of the two steels showed that the hard second phase in the matrix might be harmful to the BH ability. For deformed specimens, baking resulted in a loss of uniform elongation, but there was no obvious decrease in uniform elongation for unprestrained specimens.

  9. The Z-Phase in 9Cr Ferritic/martensitic Heat Resistant Steel

    Science.gov (United States)

    Yin, Fengshi; Chen, Fuxia; Jiang, Xuebo; Xue, Bing; Zhou, Li; Jung, Woosang

    The precipitation behavior of Z-phase was investigated during long-term aging at 650°C in an ultra low carbon 9Cr ferritic/martensitic heat resistant steel. The steel was prepared by vacuum induction melting followed by hot forging and rolling into a plate. The plate was normalized at 1100°C for 1h, cooled in air and tempered at 700°C for 1h. Bimodal nano-sized MX precipitates distribute densely and homogeneously in the matrix within martensitic lath after normalizing-and-tempering heat treatment. After aging at 650°C for 1200h, the Z-phase was found to nucleate on the larger nano-sized MX. The Z-phase and MX have the following orientation relationship: Z-phase//MX and (1bar 10){Z-phase}//(200){MX} .

  10. Relationship between hydrogen-induced phase transformations and pitting nucleation sites in duplex stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Liqiu; Yang, Binjie; Qin, Sixiao [University of Science and Technology Beijing (China). Corrosion and Protection Center

    2016-02-15

    This paper demonstrates the hydrogen-induced phase transformation and the associated pitting nucleation sites of 2507 duplex stainless steel using scanning Kelvin probe force microscopy and magnetic force microscopy. The low potential sites in Volta potential images, which are considered as the pitting nucleation sites, are strongly dependent on the hydrogen-induced phase transformation. They firstly initiate on the magnetic martensite laths in the austenite phase or at the ferrite/austenite boundaries, and then appear near the needle-shaped microtwins in the ferrite phase, because of the difference in physicochemical properties of hydrogen-induced phase transformation microstructures.

  11. Role of copper on Laves phase morphology in 9-12%Cr steels

    Science.gov (United States)

    Danielsen, Hilmar K.; Liu, Fang

    2017-07-01

    In this work the Laves phase was found to appear in two different morphologies, namely granular shapes and in an elongated shape. No difference in crystallography could be detected between these morphologies. The Laves phase was only observed in its elongated form in Cu-containing steels, where it was the primary morphology present after short term ageing. After long term ageing, the elongated Laves phase was replaced by the granular morphology. It is speculated that Cu precipitates act as nucleation sites for the elongated Laves phase, resulting in an unstable orientation relationship with the matrix, an in the meta-stable elongated morphology of Laves phase precipitates.

  12. Phase stability of high manganese austenitic steels for cryogenic applications

    CERN Document Server

    Couturier, K

    2000-01-01

    The aim of this work is to study the austenitic stability against a' martensitic transformation of three non-magnetic austenitic steels : a new stainless steel X2CrMnNiMoN 19-12-11-1 grade, a traditional X8CrMnNiN 19-11-6 grade and a high manganese X8MnCrNi 28-7-1 grade. Measurements of relative magnetic susceptibility at room temperature are performed on strained tensile specimens at 4.2 K. A special extensometer for high precision strain measurements at low temperature has been developed at CERN to test specimens up to various levels of plastic strain. Moreover, the high precision strain recording of the extensometer enables a detailed study of the serrated yield phenomena associated with 4.2 K tensile testing and their influence on the evolution of magnetic susceptibility. The results show that high Mn contents increase the stability of the austenitic structure against a' martensitic transformation, while keeping high strength at cryogenic temperature. Moreover, proper elaboration through primary and possi...

  13. Pre-Combustion Carbon Dioxide Capture by a New Dual Phase Ceramic-Carbonate Membrane Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jerry

    2014-09-30

    This report documents synthesis, characterization and carbon dioxide permeation and separation properties of a new group of ceramic-carbonate dual-phase membranes and results of a laboratory study on their application for water gas shift reaction with carbon dioxide separation. A series of ceramic-carbonate dual phase membranes with various oxygen ionic or mixed ionic and electronic conducting metal oxide materials in disk, tube, symmetric, and asymmetric geometric configurations was developed. These membranes, with the thickness of 10 μm to 1.5 mm, show CO2 permeance in the range of 0.5-5×10-7 mol·m-2·s-1·Pa-1 in 500-900oC and measured CO2/N2 selectivity of up to 3000. CO2 permeation mechanism and factors that affect CO2 permeation through the dual-phase membranes have been identified. A reliable CO2 permeation model was developed. A robust method was established for the optimization of the microstructures of ceramic-carbonate membranes. The ceramic-carbonate membranes exhibit high stability for high temperature CO2 separations and water gas shift reaction. Water gas shift reaction in the dual-phase membrane reactors was studied by both modeling and experiments. It is found that high temperature syngas water gas shift reaction in tubular ceramic-carbonate dual phase membrane reactor is feasible even without catalyst. The membrane reactor exhibits good CO2 permeation flux, high thermal and chemical stability and high thermal shock resistance. Reaction and separation conditions in the membrane reactor to produce hydrogen of 93% purity and CO2 stream of >95% purity, with 90% CO2 capture have been identified. Integration of the ceramic-carbonate dual-phase membrane reactor with IGCC process for carbon dioxide capture was analyzed. A methodology was developed to identify optimum operation conditions for a membrane tube of given dimensions that would treat coal syngas with targeted performance. The calculation results show that the dual-phase membrane reactor could

  14. Pre-Combustion Carbon Dioxide Capture by a New Dual Phase Ceramic-Carbonate Membrane Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jerry Y. S. [Arizona State Univ., Tempe, AZ (United States)

    2015-01-31

    This report documents synthesis, characterization and carbon dioxide permeation and separation properties of a new group of ceramic-carbonate dual-phase membranes and results of a laboratory study on their application for water gas shift reaction with carbon dioxide separation. A series of ceramic-carbonate dual phase membranes with various oxygen ionic or mixed ionic and electronic conducting metal oxide materials in disk, tube, symmetric, and asymmetric geometric configurations was developed. These membranes, with the thickness of 10 μm to 1.5 mm, show CO2 permeance in the range of 0.5-5×10-7 mol·m-2·s-1·Pa-1 in 500-900°C and measured CO2/N2 selectivity of up to 3000. CO2 permeation mechanism and factors that affect CO2 permeation through the dual-phase membranes have been identified. A reliable CO2 permeation model was developed. A robust method was established for the optimization of the microstructures of ceramic-carbonate membranes. The ceramic-carbonate membranes exhibit high stability for high temperature CO2 separations and water gas shift reaction. Water gas shift reaction in the dual-phase membrane reactors was studied by both modeling and experiments. It is found that high temperature syngas water gas shift reaction in tubular ceramic-carbonate dual phase membrane reactor is feasible even without catalyst. The membrane reactor exhibits good CO2 permeation flux, high thermal and chemical stability and high thermal shock resistance. Reaction and separation conditions in the membrane reactor to produce hydrogen of 93% purity and CO2 stream of >95% purity, with 90% CO2 capture have been identified. Integration of the ceramic-carbonate dual-phase membrane reactor with IGCC process for carbon dioxide capture was analyzed. A methodology was developed to identify optimum operation conditions for a

  15. Electronic Structures and Alloying Behaviors of Ferrite Phases in High Co-Ni Secondary Hardened Martensitic Steels

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@The electronic structure of ferrite (tempered martensite phase) in high Co-Ni secondary hardened martensitic steel has been investigated. The local density of states (LDOS) of alloying elements in the steel displays the relationship between solid solubility and the shape of the LDOS. The bond order integral (BOI) between atoms in the steel shows that the directional bonding of the p orbital of Si or C leads to the brittleness of the steel. At last, ∑BOI between atoms demonstrate that C, Co, Mn, Cr, Mo, Si strengthen the alloyed steel through solid-solution effects.

  16. Microstructure evolution and phase composition of high-manganese austenitic steels

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2008-12-01

    Full Text Available Purpose: The aim of the paper is to determine the influence of hot-working conditions on microstructure evolution and phase composition of new-developed high-manganese austenitic steels.Design/methodology/approach: Determination of processes controlling strain hardening was carried out in continuous compression test using Gleeble 3800 thermo-mechanical simulator. Evaluation of processes controlling work hardening and occurring after deformation at 900°C were identified by microstructure observations of the specimens solution heat-treated after plastic deformation to a true strain equal 0.23, 0.50 and 0.91. Phase composition of steels was confirmed by X-ray diffraction analysis.Findings: The steels have a fine-grained austenite microstructure with many annealing twins to a temperature of about 1000°C. The initiation of dynamic recrystallization occurs already after true deformation equal 0.29. Participation of fine grains arranged in a matrix of dynamically recovered grains essentially increases after increasing true strain to 0.5. Fully dynamically recrystallized microstructure of steel can be obtained after the true strain equal 0.9. The conditions of hot-working influence phase state of investigated steels. Steel no. 1 keeps stable austenite microstructure independently from conditions of plastic deformation. Steel with initial bi-phase microstructure keeps a certain portion of εmartensite, yet dependant on conditions of hot-working.Research limitations/implications: To determine in detail the hot-working behaviour of developed steels, a progress of microstructure evolution in subsequent stages of multi-stage compression test should be investigated.Practical implications: The obtained microstructure – hot-working conditions relationships and stress-strain curves can be useful in determination of power-force parameters of hot-rolling for sheets with fine-grained austenitic structures.Originality/value: The hot-working behaviour and

  17. Significance of the  phase for the erosive wear process of the duplex cast steel

    Directory of Open Access Journals (Sweden)

    Z. Stradomski

    2008-10-01

    Full Text Available The work presents a possibility of increasing the tribological properties of the ferritic-austenitic cast steel (the so called duplex cast steel of GX2CrNiMoCu25-6-3-3 grade by taking an advantage of the mechanism of precipitation strengthening with the σ phase arisen due to the eutectoidal ferrite decomposition. The examinations have been held using specimens cut out of both a massive casting (an impeller of about one-ton mass and a thin-walled casting (of the wall thickness about 2 mm. The huge impeller has been made of cast steel containing 0.09% of carbon (i.e. exceeding the demands of the current standard, while the thin-walled casting has been of cast steel withextremely low carbon content (0.024% due to applying the input material of a great purity. Employing the moulding material withalkaline phenolic binder hardened with CO2 and using the zirconia coating has allowed for achieving about 20% fraction of σ phase in the as-cast state of the casting. An increase in σ phase fraction in the structure of duplex cast steel results in improving the abrasive wear resistance of the material. It should be stressed that despite the high fraction of the σ phase in the material, the crack-free castings have been obtained. An addition of copper has made possible producing the high-quality thin-walled (as for cast steel castings of smoothsurfaces. No defects (including shrinkage porosity have been found.

  18. Dual correlated pumping scheme for phase noise preservation in all-optical wavelength conversion.

    Science.gov (United States)

    Anthur, Aravind P; Watts, Regan T; Shi, Kai; Carroll, John O'; Venkitesh, Deepa; Barry, Liam P

    2013-07-01

    We study the effect of transfer of phase noise in different four wave mixing schemes using a coherent phase noise measurement technique. The nature of phase noise transfer from the pump to the generated wavelengths is shown to be independent of the type of phase noise (1 / f or white noise frequency components). We then propose a novel scheme using dual correlated pumps to prevent the increase in phase noise in the conjugate wavelengths. The proposed scheme is experimentally verified by the all-optical wavelength conversion of a DQPSK signal at 10.7 GBaud.

  19. Z phase precipitation in martensitic 12CrMoVNb steels

    Science.gov (United States)

    Vodarek, V.; Strang, A.

    2003-10-01

    Precipitation of Z phase contributes significantly to degradation of creep properties of 12CrMoVNb steels because its precipitation is accompanied by dissolution offinely dispersed nitrides and carbonitrides of M2X and/or MX type. The orientation relationship between Z phase and the ferritic matrix was determined as: (001)_z// (001)_{α}, [010]_z // [010]_{α}. Prolonged thcrmal/creep exposure is accompanied by recrystallisation of the matrix and this orientation relationship is destroyed. Nevertheless Z phase particles preserve the form of thin plates. Z phase is a nitride which is rich in vanadium, niobium and chromium and its composition depends on both the temperature of precipitation and the initial chemical composition of steels. The composition of Z phase does not change during long term exposure at the original precipitation temperature. A relationship between the composition of Z phase and its temperature of formation may be able to be used as a temperature exposure indicator of steels. However it is also necessary to know the Z phase composition for a given cast of material.

  20. The anaerobic corrosion of carbon steel in alkaline media – Phase 2 results

    Directory of Open Access Journals (Sweden)

    Fennell P.A.H.

    2013-07-01

    Full Text Available In the Belgian Supercontainer concept a carbon steel overpack will surround high-level waste and spent fuel containers and be encased in a cementitious buffer material. A programme of research was carried out to investigate and measure the rate of anaerobic corrosion of carbon steel in an artificial alkaline porewater that simulates the aqueous phase in the cementitious buffer material. The corrosion rates were measured by monitoring hydrogen evolution using a manometric gas cell technique and by applying electrochemical methods. Phase 2 of the programme has repeated and extended previous Phase 1 measurements of the effects of radiation, temperature and chloride concentration of the anaerobic corrosion rate. This paper provides an update on the results from Phase 2 of the programme. The results confirm previous conclusions that the long-term corrosion rate of carbon steel in alkaline simulated porewater is determined by the formation of a thin barrier layer and a thicker outer layer composed of magnetite. Anaerobic corrosion of steel in cement requires an external supply of water.

  1. Prediction and Validation of the Austenite Phase Fraction upon Intercritical Annealing of Medium Mn Steels

    NARCIS (Netherlands)

    Farahani, H.; Xu, W.; Van der Zwaag, S.

    2015-01-01

    In this research, the effects of Mn and Si concentration and that of the isothermal intercritical holding temperature on the austenite-to-ferrite (γ → α) and the martensite-to-austenite (α′ → γ) phase transformations are studied for a series of Fe-C-Mn-Si steels with up to 7 wt pct Mn. The model is

  2. A study on Z-phase nucleation in martensitic chromium steels

    DEFF Research Database (Denmark)

    Golpayegani, Ardeshir; Andrén, Hans-Olof; Danielsen, Hilmar Kjartansson;

    2008-01-01

    9–12% chromium martensitic steels are liable to the precipitation of Z-phase, Cr(V,Nb)N, after long time exposure at 550–650 ◦C. This complex nitride consumes vanadium nitrides and causes the creep strength of the material to fall drastically after several thousand hours of exposure. In this work...

  3. The Promotion of Liquid Phase Sintering of Boron-Containing Powder Metallurgy Steels by Adding Nickel

    Directory of Open Access Journals (Sweden)

    Wu Ming-Wei

    2015-01-01

    Full Text Available Boron is a feasible alloying element for liquid phase sintering (LPS of powder metallurgy (PM steels. This study investigated the effect of nickel (Ni, which is widely used in PM steels, on the liquid phase sintering of boron-containing PM steels. The results showed that the addition of 1.8wt% Ni does not apparently modify the LPS mechanism of boron-containing PM steels. However, adding 1.8wt% Ni slightly improves the LPS densification from 0.60 g/cm3 to 0.65 g/cm3, though the green density is reduced. Thermodynamic simulation demonstrated that the presence of Ni lowers the temperature region of liquid formation, resulting in enhanced LPS densification. Moreover, original graphite powders remains in the steels sintered at 1200 ºC. These graphite powders mostly dissolve into the base iron powder when the sintering temperature is increased from 1200 ºC to 1250 ºC.

  4. Quantification of Laves Phase Particle Size in 9CrW Steel

    DEFF Research Database (Denmark)

    Korcakova, Leona; Hald, John; Somers, Marcel A.J.

    2001-01-01

    Tungsten-alloyed martensic 9Cr steels are applied for streamlines of advanced power plants because of their superior creep performance. Tungsten, as the main new alloying element, induces precipitation of intermetallic Laves phase during long-term exposure at service temperatures around 600 C....... The growth and coarsening of Laves phase was investigated for the martensitic 9CrW steel P92 after aging and after creep testing at 600 or 650 C for times up to 59,000 h. For measurement of the size of Laves phase particles, field emission gun scanning electron microscopy (FEGSEM) was used along with image...... analysis. This technique allows discrimination of Laves phase particles from M23C6 carbides. The measured particle sizes were statistically evaluated and compared with values obtained using energy-filtered transmission electron microscopy(EFTEM)....

  5. Dual-wavelength in-line phase-shifting interferometry based on two dc-term-suppressed intensities with a special phase shift for quantitative phase extraction.

    Science.gov (United States)

    Xu, Xiaoqing; Wang, Yawei; Xu, Yuanyuan; Jin, Weifeng

    2016-06-01

    To efficiently promote the phase retrieval in quantitative phase imaging, a new approach of quantitative phase extraction is proposed based on two intensities with dual wavelength after filtering the corresponding dc terms for each wavelength, in which a special phase shift is used. In this approach, only the combination of the phase-shifting technique and subtraction procedures is needed, and no additional algorithms are required. The thickness of the phase object can be achieved from the phase image, which is related to the synthetic beat wavelength. The feasibility of this method is verified by the simulated experiments of the optically transparent objects.

  6. Delta ferrite-containing austenitic stainless steel resistant to the formation of undesirable phases upon aging

    Science.gov (United States)

    Leitnaker, James M.

    1981-01-01

    Austenitic stainless steel alloys containing delta ferrite, such as are used as weld deposits, are protected against the transformation of delta ferrite to sigma phase during aging by the presence of carbon plus nitrogen in a weight percent 0.015-0.030 times the volume percent ferrite present in the alloy. The formation of chi phase upon aging is controlled by controlling the Mo content.

  7. Eddy Current Transducer Dedicated for Sigma Phase Evaluation in Duplex Stainless Steel

    Directory of Open Access Journals (Sweden)

    Grzegorz Psuj

    2012-01-01

    Full Text Available The paper describes a new transducer dedicated for evaluation of a duplex stainless steel (DSS. Different phases which exist in DSS have influence on mechanical as well as on electrical properties. Therefore, an eddy current transducer was utilized. In order to achieve high sensitivity, a differential type of the transducer was selected. The performance of the transducer was verified by utilizing the samples which had a different amount of sigma phase.

  8. Dual-frequency grating method based research on phase measurement profilometry (PMP) technology

    Science.gov (United States)

    Wang, Binbin; Liang, Yijun; Deng, Hu

    2014-11-01

    With more than three decades of development, three-dimensional optical measurement technology has reached a mature stage in commercial applications, meanwhile new ones have continually arisen. Due to the development of Charge Coupled Device (CCD) array camera and digital projection technology, the applications of Phase Measurement Profilometry (PMP) become more and more broad. Among these, dual-frequency grating method has drawn many attentions because of its simplicity in principle and optical path, low requirement of equipment, high accuracy and level of automation comparing with other methods. The phase calculation is one of the key technologies in PMP. However, phase unwrapping algorithm in PMP is a difficult issue. A lot of new algorithm have been proposed, but neither one can solve all the problems, so how to set up new phase unwrapping algorithm becomes urgent. In this chapter, we systematically investigate the phase unwrapping method in dual-frequency grating method, and experimentally set up the system. To verify our method, we experimentally measure a three dimensional object which possesses complicated stair shapes on its surface. The results show that our dual-frequency grating method could achieve phase unwrapping without doing conventional phase unwrapping calculations, and it could also detect the detailed stair shapes on the surface of this three dimensional object automatically.

  9. Determining Individual Phase Properties in a Multi-phase Q&P Steel using Multi-scale Indentation Tests

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Guang; Choi, Kyoo Sil; Hu, Xiaohua; Sun, Xin

    2016-01-15

    A new inverse method was developed to predict the stress-strain behaviors of constituent phases in a multi-phase steel using the load-depth curves measured in nanoindentation tests combined with microhardness measurements. A power law hardening response was assumed for each phase, and an empirical relationship between hardness and yield strength was assumed. Adjustment was made to eliminate the indentation size effect and indenter bluntness effect. With the newly developed inverse method and statistical analysis of the hardness histogram for each phase, the average stress-strain curves of individual phases in a quench and partitioning (Q&P) steel, including austenite, tempered martensite and untempered martensite, were calculated and the results were compared with the phase properties obtained by in-situ high energy X-ray diffraction (HEXRD) test. It is demonstrated that multi-scale instrumented indentation tests together with the new inverse method are capable of determining the individual phase flow properties in multi-phase alloys.

  10. Influence of initial thermomechanical treatment on high temperature properties of laves phase strengthened ferritic steels

    OpenAIRE

    Talik, Michal

    2016-01-01

    The aim of this work was to design 17 wt%Cr Laves phase strengthened HiperFer (Highperfomrance Ferrite) steels and evaluate their properties. This class of steel is supposed to be used in Advanced Ultra Super Critical power plants. Such cycles exhibit higher eciencyand are environmentally friendly, but improved materials with high resistance to reside/steam oxidation and sucient creep strength are required. The work focused on the characterization of creep properties of 17Cr2.5W0.5Nb0.25Si he...

  11. Synthetically Focused Imaging Techniques in Simulated Austenitic Steel Welds Using AN Ultrasonic Phased Array

    Science.gov (United States)

    Connolly, G. D.; Lowe, M. J. S.; Rokhlin, S. I.; Temple, J. A. G.

    2010-02-01

    In austenitic steel welds employed in safety-critical applications, detection of defects that may propagate during service or may have occurred during welding is particularly important. In this study, synthetically focused imaging techniques are applied to the echoes received by phased arrays in order to reconstruct images of the interior of a simulated austenitic steel weld, with application to sizing and location of simplified defects. Using a ray-tracing approach through a previously developed weld model, we briefly describe and then apply three focusing techniques. Results generated via both ray-tracing theory and finite element simulations will be shown.

  12. LOW ACTIVATION JOINING OF SIC/SIC COMPOSITES FOR FUSION APPLICATIONS: MODELING DUAL-PHASE MICROSTRUCTURES AND DISSIMILAR MATERIAL JOINTS

    Energy Technology Data Exchange (ETDEWEB)

    Henager, Charles H.; Nguyen, Ba Nghiep; Kurtz, Richard J.; Ferraris, M.; Katoh, Y.

    2016-03-31

    Finite element continuum damage models (FE-CDM) have been developed to simulate and model dual-phase joints and cracked joints for improved analysis of SiC materials in nuclear environments. This report extends the analysis from the last reporting cycle by including results from dual-phase models and from cracked joint models.

  13. Influence of initial thermomechanical treatment on high temperature properties of laves phase strengthened ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Talik, Michal

    2016-07-01

    The aim of this work was to design 17 wt%Cr Laves phase strengthened HiperFer (High performance Ferrite) steels and evaluate their properties. This class of steel is supposed to be used in Advanced Ultra Super Critical power plants. Such cycles exhibit higher efficiency and are environmentally friendly, but improved materials with high resistance to reside/steam oxidation and sufficient creep strength are required. The work focused on the characterization of creep properties of 17Cr2.5W0.5Nb0.25Si heat resistant steel. Small batches of steels with nominal compositions of 17Cr3W0.5Nb0.25Si and 17Cr3W0.9Nb0.25Si were used to analyze the influence of chemical composition on the precipitation behaviour in comparison to 17Cr2.5W0.5Nb0.25Si steel. Creep strength of HiperFer steels is ensured by ne dispersion of thermodynamically stable Laves phase particles, while maintaining high corrosion resistance by a relatively high chromium content. Design of HiperFer steels was accomplished by thermodynamic modeling (Thermocalc) with the main tasks of elimination of the unwelcome brittle (Fe,Cr)-σ phase and maximization of the content of the strengthening C14 Fe{sub 2}Nb type Laves phase particles. Long term annealing experiments of all HiperFer steels were performed at 650 C in order to evaluate the role of chemical composition and initial thermo-mechanical treatment state on precipitation behaviour. Laves phase particles formed quickly after few hours and the size of precipitates did not change significantly within 1,000 hours. The observed development of Laves phase particles was compared with thermodynamical calculations (TC-Prisma). The creep properties of 17Cr2.5W0.5Nb0.25Si steel in different initial thermo-mechanical treatment states were tested at 650 C. The influence of different cold rolling procedures, and heat treatments was investigated. Increased cold rolling deformation had a positive effect resulting not only from work hardening, but from the acceleration of

  14. Micromechanical Analyses of Debonding and Matrix Cracking in Dual-Phase Materials

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang; Yang, Qingda

    2016-01-01

    Failure in elastic dual-phase materials under transverse tension is studied numerically. Cohesive zones represent failure along the interface and the augmented finite element method (A-FEM) is used for matrix cracking. Matrix cracks are formed at an angle of 55 deg - 60 deg relative to the loading...

  15. A Dual-Stage Two-Phase Model of Selective Attention

    Science.gov (United States)

    Hubner, Ronald; Steinhauser, Marco; Lehle, Carola

    2010-01-01

    The dual-stage two-phase (DSTP) model is introduced as a formal and general model of selective attention that includes both an early and a late stage of stimulus selection. Whereas at the early stage information is selected by perceptual filters whose selectivity is relatively limited, at the late stage stimuli are selected more efficiently on a…

  16. Investigation of degenerate dual-pump phase sensitive amplifier using multi-wave model

    CERN Document Server

    Xie, Weilin; Labidi, Tarek; Bretenaker, Fabien

    2015-01-01

    Operation of a degenerate dual-pump phase sensitive amplifier (PSA) is thoroughly numerically investigated using a multi-wave model, taking into account high-order waves associated with undesired four-wave mixing (FWM) processes. More accurate phase-sensitive signal gain spectra are obtained compared to the conventional 3-wave model, leading to the precise optimization of the pump configuration in a dual-pump PSA. The signal gain spectra, as well as the phase sensitivity, are obtained and interpreted by investigating the dominant FWM processes in terms of corresponding phase matching. Moreover, the relation between dispersion slope and gain spectra is revealed, permitting the application-oriented arbitrary tailoring of the gain spectra by manipulating the dispersion profile and pump wavelength allocation.

  17. Identification, size classification and evolution of Laves phase precipitates in high chromium, fully ferritic steels.

    Science.gov (United States)

    Lopez Barrilao, Jennifer; Kuhn, Bernd; Wessel, Egbert

    2017-10-01

    To fulfil the new challenges of the German "Energiewende" more efficient, sustainable, flexible and cost-effective energy technologies are strongly needed. For a reduction of consumed primary resources higher efficiency steam cycles with increased operating parameters, pressure and temperature, are mandatory. Therefore advanced materials are needed. The present study focuses on a new concept of high chromium, fully ferritic steels. These steels, originally designed for solid oxide fuel cell applications, provide favourable steam oxidation resistance, creep and thermomechanical fatigue behaviour in comparison to conventional ferritic-martensitic steels. The strength of this type of steel is achieved by a combination of solid-solution hardening and precipitation strengthening by intermetallic Laves phase particles. The effect of alloy composition on particle composition was measured by energy dispersive X-ray spectroscopy and partly verified by thermodynamic modelling results. Generally the Laves phase particles demonstrated high thermodynamic stability during long-term annealing up to 40,000h at 600°C. Variations in chemical alloy composition influence Laves phase particle formation and consequently lead to significant changes in creep behaviour. For this reason particle size distribution evolution was analysed in detail and associated with the creep performance of several trial alloys. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Crystallite size and phase transition demeanor of ceramic steel

    Energy Technology Data Exchange (ETDEWEB)

    Gusain, Deepak; Srivastava, Varsha [Department of Chemistry, Indian Institute of Technology (Banaras Hindu University) Varanasi, Varanasi 221 005 (India); Singh, Vinay K. [Department of Ceramic Engineering, Indian Institute of Technology (Banaras Hindu University) Varanasi, Varanasi 221 005 (India); Chandra Sharma, Yogesh, E-mail: ysharma.apc@itbhu.ac.in [Department of Chemistry, Indian Institute of Technology (Banaras Hindu University) Varanasi, Varanasi 221 005 (India)

    2014-06-01

    Zirconia is an important oxide of zirconium used in variety of field ranging from dentistry, fuel cells, and thermal barrier coatings. Phase transition of zirconia is an important phenomenon controlling its fracture strength, low temperature degradability and ion conductivity. In the present study, effect of molar concentration of precursor and calcination temperature on phase transition and crystallite size of zirconia was investigated. All the samples were characterized by X-ray diffractometry (XRD), Differential Thermal Analysis/Thermogravimetric Analysis (DTA/TGA), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). In sample having lowest precursor concentration crystallite size of monoclinic zirconia was found to be lower than that of tetragonal zirconia, simultaneously with the higher proportion of tetragonal zirconia (67.62%) as compared to all other samples (42.75%–58.04%). In all cases, monoclinic to tetragonal phase transition occurs with raise of temperature but in the sample with lowest precursor concentration, tetragonal to monoclinic phase transition occurred on raising the temperature. - Graphical abstract: Display Omitted - Highlights: • Highest proportion of tetragonal phase at lowest precursor concentration. • Tetragonal phase's crystallite size decreased with rise of temperature. • Average particle size of all samples lies in the range of 13 nm–20 nm.

  19. Dual phase high-temperature membranes for CO2 separation - performance assessment in post- and pre-combustion processes.

    Science.gov (United States)

    Anantharaman, Rahul; Peters, Thijs; Xing, Wen; Fontaine, Marie-Laure; Bredesen, Rune

    2016-10-20

    Dual phase membranes are highly CO2-selective membranes with an operating temperature above 400 °C. The focus of this work is to quantify the potential of dual phase membranes in pre- and post-combustion CO2 capture processes. The process evaluations show that the dual phase membranes integrated with an NGCC power plant for CO2 capture are not competitive with the MEA process for post-combustion capture. However, dual phase membrane concepts outperform the reference Selexol technology for pre-combustion CO2 capture in an IGCC process. The two processes evaluated in this work, post-combustion NGCC and pre-combustion IGCC, represent extremes in CO2 partial pressure fed to the separation unit. Based on the evaluations it is expected that dual phase membranes could be competitive for post-combustion capture from a pulverized coal fired power plant (PCC) and pre-combustion capture from an Integrated Reforming Cycle (IRCC).

  20. How to target inter-regional phase synchronization with dual-site Transcranial Alternating Current Stimulation

    DEFF Research Database (Denmark)

    Saturnino, Guilherme Bicalho; Madsen, Kristoffer Hougaard; Siebner, Hartwig Roman

    2017-01-01

    Large-scale synchronization of neural oscillations is a key mechanism for functional information exchange among brain areas. Dual-site Transcranial Alternating Current Stimulation (ds-TACS) has been recently introduced as non-invasive technique to manipulate the temporal phase relationship of local...... oscillations in two connected cortical areas. While the frequency of ds-TACS is matched, the phase of stimulation is either identical (in-phase stimulation) or opposite (anti-phase stimulation) in the two cortical target areas. In-phase stimulation is thought to synchronize the endogenous oscillations...... and hereby to improve behavioral performance. Conversely, anti-phase stimulation is thought to desynchronize neural oscillations in the two areas, which is expected to decrease performance. Critically, in- and anti-phase ds-TACS should only differ with respect to temporal phase, while all other stimulation...

  1. Small hepatocellular carcinoma with peripheral enhancement:pathological correlation with dual phase images by helical CT

    Institute of Scientific and Technical Information of China (English)

    ZHENG Ke-guo; SHEN Jing-xian; WANG Gen-shu; XU Da-sheng

    2007-01-01

    Background The peripheral enhancement of small hepatocellular carcinoma (SHCC) is a rare appearance in dual phase images by helical computed tomography (CT). This study discusses this phenomenon and its correlative histopathology.Methods The helical CT dual phase appearance of peripheral enhancement in SHCC was analyzed in 21 cases (22 lesions). All lesions were confirmed as SHCC by histopathological examination.Results In these 22 lesions, enhanced peripheral ring in 20 lesions was incomplete, the thickness of enhanced peripheral ring varied and mural node could be found in hepatic arterial phase; only 2 lesions had complete peripheral ring enhancement and ring of uniform thickness in hepatic arterial phase. The enhancement of some peripheral rings and mural nodes dropped to very low density in portal venous phase. The tumour cells were grade Ⅰ in 3 lesions, Ⅱ in 16, Ⅲ in 2 and Ⅳ in 1. The vascular supply was more abundant at the border than in the centre of 15 lesions and the vascular supply was deficient in both centre and border of the remaining 7 lesions. In 3 lesions, the pseudocapsule showed in the border of the lesion. In 12 lesions, flecks of necrosis were found in the border and/or centre of the lesion.Conclusions The characteristic peripheral enhancement in helical CT dual phase images of small hepatocellular carcinoma correlates with different vascular supplies, fibrous capsule and necrosis of the lesion.

  2. Orientation relationships of Laves phase and NiAl particles in an AFA stainless steel

    Science.gov (United States)

    Trotter, Geneva; Baker, Ian

    2015-12-01

    The alumina-forming austenitic (AFA) stainless steel, Fe-20Cr-30Ni-2Nb-5Al (in at. %) was solutionized at 1250 °C in order to obtain a fully austenitic microstructure and then aged for up to 1325 h at 800 °C to precipitate the Laves phase and B2-NiAl particles typically found in AFAs. This paper describes detailed analyses of the orientation relationships between these particles and the matrix which were determined by transmission electron microscopy. Four variants of the (1 1 1)m//(0 0 0 1)p, ?m//? orientation relationship proposed by Denham and Silcock (J. Iron Steel Inst. 207 (1969) p.582) were observed for the Laves phase, and six variants of the (1 1 1)m//(0 1 1)p, ?m//? Kurdjumov-Sachs relationship were observed for the B2-NiAl phase.

  3. Numerical modelling of tools steel hardening. A thermal phenomena and phase transformations

    Directory of Open Access Journals (Sweden)

    T. Domański

    2010-01-01

    Full Text Available This paper the model hardening of tool steel takes into considerations of thermal phenomena and phase transformations in the solid state are presented. In the modelling of thermal phenomena the heat equations transfer has been solved by Finite Elements Method. The graph of continuous heating (CHT and continuous cooling (CCT considered steel are used in the model of phase transformations. Phase altered fractions during the continuous heating austenite and continuous cooling pearlite or bainite are marked in the model by formula Johnson-Mehl and Avrami. For rate of heating >100 K/s the modified equation Koistinen and Marburger is used. Modified equation Koistinen and Marburger identify the forming fraction of martensite.

  4. Phase transformations in low-carbon steels; modelling the kinetics in terms of the interface mobility

    Energy Technology Data Exchange (ETDEWEB)

    Leeuwen, Y. van; Kop, T.A.; Sietsma, J.; Zwaag, S. van der [Technische Univ. Delft (Netherlands). Lab. of Materials Science

    1999-09-01

    The mechanical properties of steel are determined by the microstructure that develops during the production process and is a joint result of effects of chemical composition and of heat treatment. This paper deals with the kinetics of the phase transformation between the high temperature FCC-phase austenite and the low temperature BCC-phase ferrite as it occurs during controlled cooling. In order to predict the transformation kinetics, a physical model has been developed that considers both composition effects and the actual lattice transformation rate. The model is verified against experimental dilatometry data for three lean carbon-manganese steel grades. Notwithstanding the model having no adjustable parameters, it yields adequate simulations of the transformation kinetics. (orig.)

  5. Characterization of Laves phase in Crofer 22 H stainless steel.

    Science.gov (United States)

    Hsiao, Zheng-Wen; Kuhn, Bernd; Chen, Delphic; Singheiser, Lorenz; Kuo, Jui-Chao; Lin, Dong-Yih

    2015-07-01

    This study investigated the effect of annealing temperature on the precipitation behavior of Crofer(®) 22 H at 600°C, 700°C, and 800°C. The grain size distribution, precipitate phase identification, and microstructure were analyzed using electron backscatter diffraction (EBSD) and energy dispersive X-ray spectroscopy (EDS). The morphology of Laves phase (Fe,Cr,Si)(2)(Nb,W) precipitates having the Cr(2)Nb structure changed from strip-like to needle-shaped as the annealing temperature was increased. The precipitates of the Laves phase also shifted from the grain boundaries to the grain interiors when the temperature was increased. However, the average grain size (150 μm) of the ferritic matrix did not significantly change at 600°C, 700°C, and 800°C for 10 h. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. The corrosion behavior of nano-meter embedded phase in Ti implanted H13 steel

    Institute of Scientific and Technical Information of China (English)

    张通和; 吴瑜光; 邓志威; 马芙蓉; 王晓妍; 梁宏; 周固; 赵渭江; 薛建明

    1999-01-01

    On the SEM micrographs of Ti implanted H13 steel, a tree-branch-like structure can be observed. Further investigation with TEM shows that the newly tormed composition is a formation of nann-meter FeTi2 phase in Ti implanted layer. The layer with a relatively high corrosion resistance has been formed in Ti implanted H13 steel with this structure.The results of electrochemical measurement show that the corrosion current density decreases obviously with an increase of ion dose. The corrosion current density in Ti implanted steel with a dose of 1.3×1018/cm2 is 8-20 times less than that of Ti implanted steel with a dose of 6×1017/cm2. The corrosion behavior of Ti implanted steel with a dose of 6×1017/cm2 could be further improved as the sample was annealed at 500℃ for 20 min and the corrosion current density decreases by 48-80 times compared to that of non-implanted samples. The corrosion trace was not observed on the annealing sample by SEM, after multi-sweep cyclic voltammetry of 40 cycles

  7. Phase Equilibrium and Austenite Decomposition in Advanced High-Strength Medium-Mn Bainitic Steels

    Directory of Open Access Journals (Sweden)

    Adam Grajcar

    2016-10-01

    Full Text Available The work addresses the phase equilibrium analysis and austenite decomposition of two Nb-microalloyed medium-Mn steels containing 3% and 5% Mn. The pseudobinary Fe-C diagrams of the steels were calculated using Thermo-Calc. Thermodynamic calculations of the volume fraction evolution of microstructural constituents vs. temperature were carried out. The study comprised the determination of the time-temperature-transformation (TTT diagrams and continuous cooling transformation (CCT diagrams of the investigated steels. The diagrams were used to determine continuous and isothermal cooling paths suitable for production of bainite-based steels. It was found that the various Mn content strongly influences the hardenability of the steels and hence the austenite decomposition during cooling. The knowledge of CCT diagrams and the analysis of experimental dilatometric curves enabled to produce bainite-austenite mixtures in the thermomechanical simulator. Light microscopy (LM, scanning electron microscopy (SEM, and transmission electron microscopy (TEM were used to assess the effect of heat treatment on morphological details of produced multiphase microstructures.

  8. A study on Z-phase nucleation in martensitic chromium steels

    Energy Technology Data Exchange (ETDEWEB)

    Golpayegani, Ardeshir [Department of Applied Physics, Chalmers University of Technology (Sweden)], E-mail: ardeshir.golpayegani@sandvik.com; Andren, Hans-Olof [Department of Applied Physics, Chalmers University of Technology (Sweden); Danielsen, Hilmar; Hald, John [Department of Manufacturing Engineering and Management, Technical University of Denmark (Denmark)

    2008-08-20

    9-12% chromium martensitic steels are liable to the precipitation of Z-phase, Cr(V,Nb)N, after long time exposure at 550-650 deg. C. This complex nitride consumes vanadium nitrides and causes the creep strength of the material to fall drastically after several thousand hours of exposure. In this work, initial stages of precipitation of Z-phase have been studied and characterized using energy-filtered transmission electron microscopy (EFTEM). Vanadium nitrides were found to provide the most suitable nucleation site for Z-phase, since the misfit between the (0 0 1) planes of VN and Z-phase is very small. Furthermore, such a nucleation site would provide vanadium and nitrogen for the growth of Z-phase. The presence of niobium carbide has also been observed close to Z-phase nucleation sites, indicating niobium to be important for the nucleation and growth of Z-phase.

  9. Development of Advanced High Strength Steel for Improved Vehicle Safety, Fuel Efficiency and CO2 Emission

    Science.gov (United States)

    Kumar, Satendra; Singhai, Mrigandra; Desai, Rahul; Sam, Srimanta; Patra, Pradip Kumar

    2015-12-01

    Global warming and green house gas emissions are the major issues worldwide and their impacts are clearly visible as a record high temperatures, rising sea, and severe `flooding and droughts'. Motor vehicles considered as a major contributor on global warming due to its green house gas emissions. Hence, the automobile industries are under tremendous pressure from government and society to reduce green house gas emission to maximum possible extent. In present work, Dual Phase steel with boron as microalloying is manufactured using thermo-mechanical treatment during hot rolling. Dual phase steel with boron microalloying improved strength by near about 200 MPa than dual phase steel without boron. The boron added dual phase steel can be used for manufacturing stronger and a lighter vehicle which is expected to perform positively on green house gas emissions. The corrosion resistance behavior is also improved with boron addition which would further increase the life cycle of the vehicle even under corrosive atmosphere.

  10. Development of Advanced High Strength Steel for Improved Vehicle Safety, Fuel Efficiency and CO2 Emission

    Science.gov (United States)

    Kumar, Satendra; Singhai, Mrigandra; Desai, Rahul; Sam, Srimanta; Patra, Pradip Kumar

    2016-10-01

    Global warming and green house gas emissions are the major issues worldwide and their impacts are clearly visible as a record high temperatures, rising sea, and severe `flooding and droughts'. Motor vehicles considered as a major contributor on global warming due to its green house gas emissions. Hence, the automobile industries are under tremendous pressure from government and society to reduce green house gas emission to maximum possible extent. In present work, Dual Phase steel with boron as microalloying is manufactured using thermo-mechanical treatment during hot rolling. Dual phase steel with boron microalloying improved strength by near about 200 MPa than dual phase steel without boron. The boron added dual phase steel can be used for manufacturing stronger and a lighter vehicle which is expected to perform positively on green house gas emissions. The corrosion resistance behavior is also improved with boron addition which would further increase the life cycle of the vehicle even under corrosive atmosphere.

  11. Progress in Dual (Piezoelectric-Magnetostrictive Phase Magnetoelectric Sintered Composites

    Directory of Open Access Journals (Sweden)

    Rashed Adnan Islam

    2012-01-01

    Full Text Available The primary aims of this review article are (a to develop the fundamental understanding of ME behavior in perovskite piezoelectric-spinel magnetostrictive composite systems, (b to identify the role of composition, microstructural variables, phase transformations, composite geometry, and postsintering heat treatment on ME coefficient, and (c to synthesize, characterize, and utilize the high ME coefficient composite. The desired range of ME coefficient in the sintered composite is 0.5–1 V/cm⋅Oe. The studies showed that the soft piezoelectric phase quantified by smaller elastic modulus, large grain size of piezoelectric phase (~1 μm, and layered structures yields higher magnitude of ME coefficient. It is also found that postsintering thermal treatment such as annealing and aging alters the magnitude of magnetization providing an increase in the magnitude of ME coefficient. A trilayer composite was synthesized using pressure-assisted sintering with soft phase [0.9 PZT–0.1 PZN] having grain size larger than 1 μm and soft ferromagnetic phase of composition Ni0.8Cu0.2Zn0.2Fe2O4 [NCZF]. The composite showed a high ME coefficient of 412 and 494 mV/cm⋅Oe after sintering and annealing, respectively. Optimized ferrite to PZT thickness ratio was found to be 5.33, providing ME coefficient of 525 mV/cm⋅Oe. The ME coefficient exhibited orientation dependence with respect to applied magnetic field. Multilayering the PZT layer increased the magnitude of ME coefficient to 782 mV/cm⋅Oe. Piezoelectric grain texturing and nanoparticulate assembly techniques were incorporated with the layered geometry. It was found that with moderate texturing, d33 and ME coefficient reached up to 325 pC/N and 878 mV/cm⋅Oe, respectively. Nanoparticulate core shell assembly shows the promise for achieving large ME coefficient in the sintered composites. A systematic relationship between composition, microstructure, geometry, and properties is

  12. Evaluation with low-dose dual-phase helical computed tomography of patients with thyroid lesions

    Institute of Scientific and Technical Information of China (English)

    Li Lin; Wang Yong; Zhao Yanfeng; Zou Shuangmei; Lin Meng; Yu Xiaoduo; Tang Wei

    2014-01-01

    Background The incidence of thyroid cancer has been increasing.Our aim was to evaluate the efficacy of low-dose dualphase helical computed tomography (CT) in the characterization of thyroid lesions,and to discuss the relationship between image characteristics and their pathology.Methods One hundred and six patients with thyroid lesions underwent low-dose dual-phase helical CT after the injection of contrast material.CT scans were obtained at arterial and venous phase with delays of 25 and 65 seconds,and tube current of 60 and 120 mA,respectively.The attenuation change in the lesion between the arterial and venous phase was analyzed and categorized as "increased," "decreased," "mixed" or "no change." Results Histopathologic diagnosis was obtained by surgery in 106 patients (115 lesions).Of the 106 patients,45 had nodular goiter,5 thyroid adenoma,6 thyroiditis,and 50 papillary thyroid carcinoma (PTC) (59 lesions).The attenuation value showed a significant difference (P <0.05) between the arterial and venous phase for the high attenuation area.There was statistical significant difference in terms of attenuation value in high attenuation areas at both phases and in low attenuation areas on arterial phase between nodular goiter and PTC (P <0.05).However,there was no significant difference in attenuation value between adenoma and PTC.Twenty-nine cases (76.3%) of goiter manifested mixed type,3 cases (3/5) of adenoma showed decreased type,6 cases (6/6) of thyroiditis showed increased type,and 55 cases (93.2%) of PTC showed decreased type attenuation.The sensitivity,specificity for thyroid carcinoma by dual-phase CT were 94.9% and 80.4% respectively.The overall diagnostic accuracy for thyroid lesions by dual-phase CT was 87.8%.Conclusions The performance of dual-phase helical CT is related to the pathological structure of the lesions.The analysis of enhancement patterns by using dual-phase helical CT will be helpful in the differential diagnosis of thyroid

  13. Nanometric Scale Investigation of Phase Transformations in Advanced Steels for Automotive Application

    Science.gov (United States)

    Drillet, Josée; Valle, Nathalie; Iung, Thierry

    2012-12-01

    The current trend toward producing lighter vehicles in the automotive industry is driven by the need to conform to the new exhaust emission control regulations. This objective presents a challenge to steel manufacturers. The difficulty lies in designing new alloys with an optimum strength/formability/cost balance for the various components. Here, the key to success lies in controlling the steel microstructure and especially the phase transformations at the smallest possible scale. Among the different alloying elements, light elements such as carbon and boron are of prime importance due to their major effects on the kinetics of phase transformations. Characterization tools combining high spatial and analytical resolution such as secondary ion mass spectrometry (SIMS) and field emission gun-transmission electron microscopy (TEM) were used. In this article, the examples presented are as follows. (1) Boron segregation and precipitation effects to control hardenability in martensitic steels. (2) Local carbon distribution in advanced high-strength steels, with a specific emphasis on martensite tempering. Links have been established between the boron and carbon distribution and the formability.

  14. Dual view on sliding phases in U (1 ) symmetric systems

    Science.gov (United States)

    Vayl, S.; Kuklov, A. B.; Oganesyan, V.

    2017-03-01

    The proposal of sliding phases (SP) is revisited from the perspective of duality. A generic argument is formulated as essentially a no-go theorem for SP in translationally invariant nonfrustrated systems with short-range interactions—classical or quantum. Its validity is demonstrated on an asymmetric bilayer and its multilayer variation models where the duality allows obtaining asymptotically exact analytical solution. This solution is in drastic contrast with the perturbative renormalization group prediction and is strongly supported by Monte Carlo simulations. An alternative path toward finding SP is suggested. Its key ingredient is a long-range gauge-type interaction suppressing the interlayer Josephson coupling.

  15. Open-Phase Fault Tolerance Techniques of Five-Phase Dual-Rotor Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Jing Zhao

    2015-11-01

    Full Text Available Multi-phase motors are gaining more attention due to the advantages of good fault tolerance capability and high power density, etc. By applying dual-rotor technology to multi-phase machines, a five-phase dual-rotor permanent magnet synchronous motor (DRPMSM is researched in this paper to further promote their torque density and fault tolerance capability. It has two rotors and two sets of stator windings, and it can adopt a series drive mode or parallel drive mode. The fault-tolerance capability of the five-phase DRPMSM is researched. All open circuit fault types and corresponding fault tolerance techniques in different drive modes are analyzed. A fault-tolerance control strategy of injecting currents containing a certain third harmonic component is proposed for five-phase DRPMSM to ensure performance after faults in the motor or drive circuit. For adjacent double-phase faults in the motor, based on where the additional degrees of freedom are used, two different fault-tolerance current calculation schemes are adopted and the torque results are compared. Decoupling of the inner motor and outer motor is investigated under fault-tolerant conditions in parallel drive mode. The finite element analysis (FMA results and co-simulation results based on Simulink-Simplorer-Maxwell verify the effectiveness of the techniques.

  16. Nanomaterial-based biosensors using dual transducing elements for solution phase detection.

    Science.gov (United States)

    Li, Ning; Su, Xiaodi; Lu, Yi

    2015-05-07

    Biosensors incorporating nanomaterials have demonstrated superior performance compared to their conventional counterparts. Most reported sensors use nanomaterials as a single transducer of signals, while biosensor designs using dual transducing elements have emerged as new approaches to further improve overall sensing performance. This review focuses on recent developments in nanomaterial-based biosensors using dual transducing elements for solution phase detection. The review begins with a brief introduction of the commonly used nanomaterial transducers suitable for designing dual element sensors, including quantum dots, metal nanoparticles, upconversion nanoparticles, graphene, graphene oxide, carbon nanotubes, and carbon nanodots. This is followed by the presentation of the four basic design principles, namely Förster Resonance Energy Transfer (FRET), Amplified Fluorescence Polarization (AFP), Bio-barcode Assay (BCA) and Chemiluminescence (CL), involving either two kinds of nanomaterials, or one nanomaterial and an organic luminescent agent (e.g. organic dyes, luminescent polymers) as dual transducers. Biomolecular and chemical analytes or biological interactions are detected by their control of the assembly and disassembly of the two transducing elements that change the distance between them, the size of the fluorophore-containing composite, or the catalytic properties of the nanomaterial transducers, among other property changes. Comparative discussions on their respective design rules and overall performances are presented afterwards. Compared with the single transducer biosensor design, such a dual-transducer configuration exhibits much enhanced flexibility and design versatility, allowing biosensors to be more specifically devised for various purposes. The review ends by highlighting some of the further development opportunities in this field.

  17. The microstructure and phase relationships in rapidly solidified type 304 stainless steel powders

    Science.gov (United States)

    Wright, Richard N.; Flinn, John E.; Korth, Gary E.; Bae, Jung Chan; Kelly, Thomas F.

    1988-10-01

    The microstructure and relative amounts of fcc and bcc phases have been studied for rapidly solidified Type 304 stainless steel powders produced by vacuum gas atomization (VGA) and centrifugal atomization (CA). The VGA powder solidifies with a cellular microstructure while the CA powder has a dendritic microstructure. The volume fraction of fcc phase in the CA powder is found to increase from 40 Pct to 97 Pct with increasing particle size from 30 to 125 µm. In the VGA powder, the volume fraction of fcc phase is found to decrease from about 90 Pct to 77 Pct over the same range of particle sizes. The origins of the fcc and bcc phases in each powder are considered. It is concluded that bcc is present as both a primary crystallization phase in the smaller CA particles (<75 µm) and as compositionally stabilized eutectic ferrite at the cell walls of particles of both CA and VGA powders in which fcc was the primary crystallization phase.

  18. Effect of Secondary Phase Precipitation on the Corrosion Behavior of Duplex Stainless Steels

    Directory of Open Access Journals (Sweden)

    Kai Wang Chan

    2014-07-01

    Full Text Available Duplex stainless steels (DSSs with austenitic and ferritic phases have been increasingly used for many industrial applications due to their good mechanical properties and corrosion resistance in acidic, caustic and marine environments. However, DSSs are susceptible to intergranular, pitting and stress corrosion in corrosive environments due to the formation of secondary phases. Such phases are induced in DSSs during the fabrication, improper heat treatment, welding process and prolonged exposure to high temperatures during their service lives. These include the precipitation of sigma and chi phases at 700–900 °C and spinodal decomposition of ferritic grains into Cr-rich and Cr-poor phases at 350–550 °C, respectively. This article gives the state-of the-art review on the microstructural evolution of secondary phase formation and their effects on the corrosion behavior of DSSs.

  19. Formation of laves phase in a refractory austenitic steel due to long-term heating

    Science.gov (United States)

    Tarasenko, L. V.; Shal'kevich, A. B.

    2011-07-01

    Steels of the Fe - Cr - Ni -Mo - Nb - Al - C system are studied by methods of phase physicochemical analysis and electron microscopy with the aim to determine the causes of changes in mechanical properties after long-term heating at a temperature of 600 - 700°C. Grain-boundary formation of particles of a Laves phase is shown to cause decrease in the impact toughness and transformation of particles of γ'-phase under conditions of creep. The effect of alloying elements on the chemical composition of the multicomponent Laves phase is studied depending on the temperatures of hardening, aging, and subsequent heating. Concentration correspondence between the chemical composition of the austenite and the intermetallic tcp phase formed in aging is discovered. A computational scheme for predicting the possibility of formation of Laves phases in multicomponent alloys is suggested.

  20. Diffusion of nitrogen in austenitic phase: Application to nitriding of stainless steels

    Directory of Open Access Journals (Sweden)

    Torchane Lazhar

    2014-04-01

    Full Text Available The nitriding treatment of the martensitic stainless steels aims to harden and to introduce compressive stresses on the surface of steel. Hardening is resulting of the martensitic transformation of the austenitic matrix enriched into nitrogen during cooling and of the germination and the nitride growth. In order to preserve the stainless character of the nitrided layer, it is imperative to control precipitation within the zone affected by the treatment. Our task consists in showing that is possible to control the composition of the gas atmosphere containing ammonia and argon and to carry out on the surface of nitrided samples at 1050°C two types of configuration of layers : a single phase layer made up by martensite enriched in nitrogen α’N and or a two phase layer made up by austenite γN and martensite α’N enriched in nitrogen.

  1. Corrosion properties of S-phase layers formed on medical grade austenitic stainless steel.

    Science.gov (United States)

    Buhagiar, Joseph; Dong, Hanshan

    2012-02-01

    The corrosion properties of S-phase surface layers formed in AISI 316LVM (ASTM F138) and High-N (ASTM F1586) medical grade austenitic stainless steels by plasma surface alloying with nitrogen (at 430°C), carbon (at 500°C) and both carbon and nitrogen (at 430°C) has been investigated. The corrosion behaviour of the S-phase layers in Ringer's solutions was evaluated using potentiodynamic and immersion corrosion tests. The corrosion damage was evaluated using microscopy, hardness testing, inductive coupled plasma mass spectroscopy and X-ray diffraction. The experimental results have demonstrated that low-temperature nitriding, carburising and carbonitriding can improve the localised corrosion resistance of both industrial and medical grade austenitic stainless steels as long as the threshold sensitisation temperature is not reached. Carburising at 500°C has proved to be the best hardening treatment with the least effect on the corrosion resistance of the parent alloy.

  2. Phase synchronization based on a Dual-Tree Complex Wavelet Transform

    Science.gov (United States)

    Ferreira, Maria Teodora; Domingues, Margarete Oliveira; Macau, Elbert E. N.

    2016-11-01

    In this work, we show the applicability of our Discrete Complex Wavelet Approach (DCWA) to verify the phenomenon of phase synchronization transition in two coupled chaotic Lorenz systems. DCWA is based on the phase assignment from complex wavelet coefficients obtained by using a Dual-Tree Complex Wavelet Transform (DT-CWT). We analyzed two coupled chaotic Lorenz systems, aiming to detect the transition from non-phase synchronization to phase synchronization. In addition, we check how good is the method in detecting periods of 2π phase-slips. In all experiments, DCWA is compared with classical phase detection methods such as the ones based on arctangent and Hilbert transform showing a much better performance.

  3. A popular metastable omega phase in body-centered cubic steels

    Energy Technology Data Exchange (ETDEWEB)

    Ping, D.H., E-mail: ping.de-hai@nims.go.jp [National Institute for Materials Science, Sengen 1-2-1, Tsukuba 305-0047 (Japan); Geng, W.T., E-mail: geng@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2013-05-15

    Steel remains to be one of the most common structural materials in the world as human civilization advances from the Iron Age to the ongoing Silicon Age. Our knowledge of its microstructure evolution and structure–performance relationship is nevertheless still incomplete. We report the observation and characterization of a long ignored metastable phase formed in steels with body-centered cubic (bcc) structure using both transmission electron microscopy and density functional theory calculations. This ω phase has a hexagonal structure and coherent interface with the matrix: a{sub ω} = √2 × a{sub bcc} and c{sub ω} = √3/2 × a{sub bcc}. It is 3.6% smaller in volume and 0.18 eV higher in energy than bcc-Fe, with atoms in alternating close- and loose-packed layers couple anti-ferromagnetically. Carbon plays a crucial role in promoting bcc to ω transformation. At a concentration higher than 4 at.% they tend to segregate from the bcc matrix to the ω-phase; at about 14 at.%, they can induce bcc to ω transformation; and finally at 25 at.%, they stabilize the ω phase as ω-Fe{sub 3}C. The ω phase in bcc Fe can serve as sinks for vacancies, H, and He atoms, leading to improved resistance of martensitic steels to irradiation damage. - Highlights: ► A long-ignored metastable ω phase in body-centered cubic (bcc) steel. ► The ω phase has hexagonal structure with lattice parameters a{sub ω} = √2 × a{sub bcc} and c{sub ω} = √3/2 × a{sub bcc}. ► Carbon enrichment is found to play a crucial role on the bcc-to-ω phase transformation. ► The ω phase is strongly related to the martensitic transformation and twinning structure. ► The ω phase in bcc Fe can serve as sinks for vacancies, H, and He atoms.

  4. Dual Mode Sensing with Low-Profile Piezoelectric Thin Wafer Sensors for Steel Bridge Crack Detection and Diagnosis

    Directory of Open Access Journals (Sweden)

    Lingyu Yu

    2012-01-01

    Full Text Available Monitoring of fatigue cracking in steel bridges is of high interest to many bridge owners and agencies. Due to the variety of deterioration sources and locations of bridge defects, there is currently no single method that can detect and address the potential sources globally. In this paper, we presented a dual mode sensing methodology integrating acoustic emission and ultrasonic wave inspection based on the use of low-profile piezoelectric wafer active sensors (PWAS. After introducing the research background and piezoelectric sensing principles, PWAS crack detection in passive acoustic emission mode is first presented. Their acoustic emission detection capability has been validated through both static and compact tension fatigue tests. With the use of coaxial cable wiring, PWAS AE signal quality has been improved. The active ultrasonic inspection is conducted by the damage index and wave imaging approach. The results in the paper show that such an integration of passive acoustic emission detection with active ultrasonic sensing is a technological leap forward from the current practice of periodic and subjective visual inspection and bridge management based primarily on history of past performance.

  5. Investigation of phase transformation for ferrite–austenite structure in stainless steel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Merakeb, Noureddine [Laboratory of Physical Metallurgy and Property of Materials (LM2PM), Metallurgy and Materials Engineering Department, Badji Mokhtar University, P.O. Box 12, Annaba 23000 (Algeria); Messai, Amel [Laboratoire d' Ingénierie et Sciences des Matériaux Avancés (ISMA), Institut des Sciences et Technologie, Abbès Laghrour University, Khenchela 40000 (Algeria); Ayesh, Ahmad I., E-mail: ayesh@qu.edu.qa [Department of Mathematics, Statistics and Physics, Qatar University, Doha (Qatar)

    2016-05-01

    In this work we report on phase transformation of 304 stainless steel thin films due to heat treatment. Ex-situ annealing was applied for evaporated 304 stainless steel thin films inside an ultra-high vacuum chamber with a pressure of 3 × 10{sup −7} Pa at temperatures of 500 °C and 600 °C. The structure of thin films was studied by X-ray diffraction (XRD) and conversion electron Mössbauer spectroscopy (CEMS) techniques. The results revealed a transformation from α-phase that exhibits a body-centered cubic structure (BCC) to γ-phase that exhibits a face-centered cubic (FCC) due to annealing. In addition, the percentage of γ-phase structure increased with the increase of annealing temperature. Annealing thin films increased the crystal size of both phases (α and γ), however, the increase was nonlinear. The results also showed that phase transformation was produced by recrystallization of α and γ crystals with a temporal evolution at each annealing temperature. The texture degree of thin films was investigated by XRD rocking curve method, while residual stress was evaluated using curvature method. - Highlights: • Stainless steel thin films were fabricated by thermal evaporation on quartz. • Alpha to gamma phase transformation of thin films was investigated. • Annealing of thin films reduces disruption in crystal lattice. • The stress of as-grown thin films was independent on the thin film thickness. • The stress of the thin films was reduced due to annealing.

  6. Effects of Microalloying in Multi Phase Steels for Car Body Manufacture

    Science.gov (United States)

    Bleck, Wolfgang; Phiu-On, Kriangyut

    Microalloying elements like Al, B, Nb, Ti, V can be used to optimise the microstructure evolution and the mechanical properties of advanced high strength steels (AHSS). Microalloying elements are characterised by small additions AHSS with their high requirements to process control can be adopted to existing processing lines. Different combinations of microstructural phases and different chemical compositions have been investigated for AHSS in order to combine high strength with excellent formability.

  7. Influence of cooling rate on secondary phase precipitation and proeutectoid phase transformation of micro-alloyed steel containing vanadium

    Science.gov (United States)

    Dou, Kun; Meng, Lingtao; Liu, Qing; Liu, Bo; Huang, Yunhua

    2016-05-01

    During continuous casting process of low carbon micro-alloyed steel containing vanadium, the evolution of strand surface microstructure and the precipitation of secondary phase particles (mainly V(C, N)) are significantly influenced by cooling rate. In this paper, influence of cooling rate on the precipitation behavior of proeutectoid α-ferrite at the γ-austenite grain boundary and in the steel matrix are in situ observed and analyzed through high temperature confocal laser scanning microscopy. The relationship between cooling rate and precipitation of V(C, N) from steel continuous casting bloom surface microstructure is further studied by scanning electron microscopy and electron dispersive spectrometer. Relative results have shown the effect of V(C, N) precipitation on α-ferrite phase transformation is mainly revealed in two aspects: (i) Precipitated V(C, N) particles act as inoculant particles to promote proeutectoid ferrite nucleation. (ii) Local carbon concentration along the γ-austenite grain boundaries is decreased with the precipitation of V(C, N), which in turn promotes α-ferrite precipitation.

  8. Cavity nucleation and growth in dual beam irradiated 316L industrial austenitic stainless steel

    Science.gov (United States)

    Jublot-Leclerc, S.; Li, X.; Legras, L.; Fortuna, F.; Gentils, A.

    2017-10-01

    Thin foils of 316L were simultaneously ion irradiated and He implanted in situ in a Transmission Electron Microscope at elevated temperatures. The resulting microstructure is carefully investigated in comparison with previous single ion irradiation experiments with a focus on the nucleation and growth of cavities. Helium is found to strongly enhance the nucleation of cavities in dual beam experiments. On the contrary, it does not induce more nucleation when implanted consecutively to an in situ ion irradiation but rather the growth of cavities by absorption at existing cavities, which shows the importance of synergistic effects and He injection mode on the microstructural changes. In both dual beam and single beam experiments, the characteristics of the populations of cavities, either stabilized by He or O atoms, are in qualitative agreement with the predictions of rate theory models for cavity growth. The evolutions of cavity population as a function of irradiation conditions can be reasonably well explained by the concept of relative sink strength of cavities and dislocations and the resulting partitioning of defects at sinks, or conversely recombination when either of the sinks dominates. The dislocations whose presence is a prerequisite to cavity growth in rate theory models are not observed in all studied conditions. In this case, the net influx of vacancies to cavities necessary to their growth and conversion to voids is believed to result from free surface effects, and possibly also segregation of elements close to the cavity surface. In any studied condition, the measured swelling is low, which is ascribed to the dilution of gaseous atoms among a high density of cavities as well as a high rate of point defect recombination and loss at traps. This high rate of recombination enhanced when dislocations are absent appears to result in the formation of overpressurized He bubbles.

  9. Influence of Z-phase on long-term creep stability of martensitic 9-12% Cr steels

    Energy Technology Data Exchange (ETDEWEB)

    Danielsen, Hilmar K. [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Mechanical Engineering; Hald, John [DONG Energy A/S (Denmark); Vattenfall (Denmark)

    2010-07-01

    The long-term creep strength of the new generation of martensitic creep resistant 9-12%Cr steels since the well-known steel Grade 91 relies strongly on particle strengthening by fine Mn nitrides based on V and Nb. During long-term high-temperature exposures the Mn nitrides may be replaced by the thermodynamically more stable Z-phases (Cr(V,Nb)N) causing a breakdown in creep strength. Cr contents above 10.5% strongly accelerate Z-phase precipitation, which explains the lack of success for all attempts to develop martensitic creep resistant steels with high Cr content for oxidation protection. However 9%Cr steels do not seem to be affected by the Z-phase. Careful control of the Z-phase precipitation process has led to the design of experimental 12%Cr martensitic steels strengthened by fine Z-phase nitrides based on Nb or Ta. Such steels may again enable the combination of high strength and oxidation resistance in the same alloy. This opens a new pathway for further alloy development of the heat resistant martensitic steels. (orig.)

  10. Cracking kinetics of two-phase stainless steel alloys in hydrogen gas

    Science.gov (United States)

    Perng, T.-P.; Altstetter, C. J.

    1988-01-01

    The kinetics of hydrogen-induced slow crack growth (SCG) under constant load was studied in two stainless steel alloys containing mixtures of bcc and fcc phases. FERRALIUM 255, a duplex stainless steel, consisting of ˜50 pct austenite in a ferrite matrix, was tested in hydrogen gas at 0 to 100 °C with the loading axis both perpendicular and parallel to the rolling direction. In addition, specimens of AISI 301 were deformed in air in different ways to produce various amounts of bcc phase in an austenite matrix prior to testing in H2 gas at room temperature. The kinetics of subcritical slow crack growth (SCG) in these alloys was compared with that for austenitic and for ferritic stainless steels. The SCG rates were rationalized in terms of differences in hydrogen permeation in the two phases. The results confirm that a higher rate of supply and accumulation of hydrogen in the region ahead of the crack tip allows a higher cracking velocity.

  11. High-Precision Half-Wave Rectifier Circuit In Dual Phase Output Mode

    Directory of Open Access Journals (Sweden)

    Theerayut Jamjaem

    2009-12-01

    Full Text Available This paper present high-precision half-wave rectifier circuit in dual phase output mode by 0.5 μm CMOS technology, +/- 1.5 V low voltage, it has received input signal and sent output current signal, respond in high frequency. The main structure compound with CMOS inverter circuit, common source circuit, and current mirror circuit. Simulation and confirmation quality of working by PSpice program, then it able to operating at maximum frequency about 100 MHz, maximum input current range about 400 μAp-p, high precision output signal, low power dissipation, and uses a little transistor.Keywords-component; half-wave; rectifier circuit; highprecession; dual phase;

  12. Stability and Thermodynamic Restrictions for a Dual-Phase-Lag Thermal Model

    Science.gov (United States)

    Fabrizio, Mauro; Lazzari, Barbara; Tibullo, Vincenzo

    2017-06-01

    In this paper, the seeming inconsistency highlighted by Fabrizio and Lazzari (Stability and second law of thermodynamics in dual-phase-lag heat conduction, Int. J. Heat Mass Transfer 74 (2014), 484-489) and Quintanilla and Racke (A note on stability of dual-phase-lag heat conduction, Int. J. Heat Mass Transfer 49 (2007), 1209-1213) for a thermoelastic material, between the thermodynamic restrictions and the stability conditions is studied. Actually, we show as these results are due to the use of different formulations of the thermodynamic principles, which are not always equivalent. So that, we prove by the model considered in the paper that these two formulations do not lead to the same restrictions on the constitutive equations. This analysis allowed us to restore the compatibility by an appropriate and wide representation of the Second Law.

  13. A dual phase lag model on photothermal interaction in an unbounded semiconductor medium with cylindrical cavity

    Science.gov (United States)

    Abbas, Ibrahim A.

    2016-09-01

    In the present paper, the theory of generalized photo-thermoelasticity under dual phase lag model has been applied to study the coupled thermal, plasma and elastic waves on unbounded semiconductor medium with cylindrical cavity. The bounding surface of the cavity is traction free and loaded thermally by exponentially decaying pulse boundary heat flux. By using Laplace transform and the eigenvalue approach methodology, the solutions of all variables have been obtained analytically. Numerical computations have been done for silicon-like semiconductor material, and the results are displayed graphically to show the difference between the dual phase lag (DPL) model, Lord and Shulman’s theory (LS) and the classical dynamical coupled theory (CT).

  14. Experimental demonstration of a dual-frequency laser free from anti-phase noise

    CERN Document Server

    Amili, Abdelkrim El; De, Syamsundar; Schwartz, Sylvain; Feugnet, Gilles; Pocholle, Jean-Paul; Bretenaker, Fabien; Alouini, Mehdi

    2012-01-01

    A reduction of more than 20 dB of the intensity noise at the anti-phase relaxation oscillation frequency is experimentally demonstrated in a two-polarization dual-frequency solid-state laser without any optical or electronic feedback loop. Such a behavior is inherently obtained by aligning the two orthogonally polarized oscillating modes with the crystallographic axes of a (100)-cut neodymium-doped yttrium aluminum garnet active medium. The anti-phase noise level is shown to increase as soon as one departs from this peculiar configuration, evidencing the predominant role of the nonlinear coupling constant. This experimental demonstration opens new perspectives on the design and realization of extremely low noise dual-frequency solid-state lasers.

  15. Laser welding of advanced high strength steels

    OpenAIRE

    Ahmed, Essam Ahmed Ali

    2011-01-01

    This research work focuses on characterization of CO2 laser beam welding (LBW) of dual phase (DP) and transformation induced plasticity (TRIP) steel sheets based on experimental, numerical simulation and statistical modeling approaches. The experimental work aimed to investigate the welding induced-microstructures, hardness, tensile properties and formability limit of laser welding butt joints of DP/DP, TRIP/TRIP and DP/TRIP steel sheets under different welding speeds. The effects of shieldin...

  16. Effect of aging temperature on phase decomposition and mechanical properties in cast duplex stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Mburu, Sarah; Kolli, R. Prakash; Perea, Daniel E.; Schwarm, Samuel C.; Eaton, Arielle; Liu, Jia; Patel, Shiv; Bartrand, Jonah; Ankem, Sreeramamurthy

    2017-04-01

    The microstructure and mechanical properties in unaged and thermally aged (at 280 oC, 320 oC, 360 oC, and 400 oC to 4300 h) CF–3 and CF–8 cast duplex stainless steels (CDSS) are investigated. The unaged CF–8 steel has Cr-rich M23C6 carbides located at the δ–ferrite/γ– austenite heterophase interfaces that were not observed in the CF–3 steel and this corresponds to a difference in mechanical properties. Both unaged steels exhibit incipient spinodal decomposition into Fe-rich α–domains and Cr-rich α’–domains. During aging, spinodal decomposition progresses and the mean wavelength (MW) and mean amplitude (MA) of the compositional fluctuations increase as a function of aging temperature. Additionally, G–phase precipitates form between the spinodal decomposition domains in CF–3 at 360 oC and 400 oC and in CF–8 at 400 oC. The microstructural evolution is correlated to changes in mechanical properties.

  17. Phase Evolution in Boride-Based Cermets and Reaction Bonding onto Plain Low Carbon Steel Substrate

    Science.gov (United States)

    Palanisamy, B.; Upadhyaya, A.

    2012-04-01

    Reaction sinter bonding is a process that aims to bond two materials for improvement in properties through reactive sintering technique. The process has been effectively used to sinter hard materials like borides in situ which not only possess excellent oxidation resistance, good corrosion resistance but also resistant to abrasive wear. Sinter bonding is a unique surface modification process achieved through powder metallurgy and is competent with other techniques like boronizing sintering and sinter-brazing since it eliminates the additional operations of heat treatment and assembly and removes the inherent setbacks with these processes. This study focuses on identifying the phase evolution mechanism using characterization tools like x-ray diffractometry and energy dispersive spectroscopy and study of sinter bonding of the boron containing precursors (Mo-Cr-Fe-Ni-FeB-MoB) onto plain carbon steel. A microstructure containing Fe-based matrix dispersed with complex borides develops with temperature in the tape cast sheets. A fivefold increase in hardness between plain carbon steel in wrought condition and sinter bonded steel was observed. The multilayer consisted of a reaction zone adjacent to the interface and was investigated with the composition profile and hardness measurements. A model of sinter bonding between the cermet and the steel has also been proposed.

  18. Thermophysical Properties of Five Industrial Steels in the Solid and Liquid Phase

    Science.gov (United States)

    Wilthan, B.; Schützenhöfer, W.; Pottlacher, G.

    2017-07-01

    The need for characterization of thermophysical properties of steel was addressed in the FFG-Bridge Project 810999 in cooperation with our partner from industry, Böhler Edelstahl GmbH & Co KG. To optimize numerical simulations of production processes such as plastic deformation or remelting, additional and more accurate thermophysical property data were necessary for the group of steels under investigation. With the fast ohmic pulse heating circuit system and a commercial high-temperature Differential Scanning Calorimeter at Graz University of Technology, we were able to measure the temperature-dependent specific electrical resistivity and specific enthalpy for a set of five high alloyed steels: E105, M314, M315, P800, and V320 from room temperature up into the liquid phase. The mechanical properties of those steels make sample preparation an additional challenge. The described experimental approach typically uses electrically conducting wire-shaped specimen with a melting point high enough for the implemented pyrometric temperature measurement. The samples investigated here are too brittle to be drawn as wires and could only be cut into rectangular specimen by Electrical Discharge Machining. Even for those samples all electrical signals and the temperature signal can be recorded with proper alignment of the pyrometer. For each material under investigation, a set of data including chemical composition, solidus and liquidus temperature, enthalpy, electrical resistivity, and thermal diffusivity as a function of temperature will be reported.

  19. Monte Carlo simulation of spinodal decomposition in a ternary alloy within a three-phases field: comparison to phase transformation of ferrite in duplex stainless steels

    Science.gov (United States)

    Emo, Jonathan; Pareige, Cristelle; Saillet, Sébastien; Domain, Christophe; Pareige, Philippe

    2014-06-01

    This work proposes to model phase transformations occurring in duplex stainless steels using atomistic kinetic Monte Carlo in a ternary model alloy. Kinetics are simulated in the three-phase field of a ternary system. Influence of the precipitation of the third phase on the kinetic of spinodal decomposition between the two other phases is studied in order to understand the synergy between spinodal decomposition and G-phase precipitation which exists in duplex stainless steels. Simulation results are compared to experimental data obtained with atom probe tomography.

  20. A novel CO2- and SO2-tolerant dual phase composite membrane for oxygen separation

    DEFF Research Database (Denmark)

    Cheng, Shiyang; Søgaard, Martin; Han, Li;

    2015-01-01

    A novel dual phase composite oxygen membrane (Al0.02Ga0.02Zn0.96O1.02 – Gd0.1Ce0.9O1.95-δ) was successfully prepared and tested. The membrane shows chemical stability against CO2 and SO2, and a stable oxygen permeation over 300 hours in CO2 was demonstrated. ZnO is cheap and non...

  1. Tuning into blue and red luminescence in dual-phase nano-glass–ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Daqin, E-mail: dqchen@hdu.edu.cn [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Wan, Zhongyi; Zhou, Yang; Zhong, Jiasong; Ding, Mingye; Yu, Hua; Lu, Hongwei [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Xiang, Weidong [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China); Ji, Zhenguo, E-mail: jizg@hdu.edu.cn [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2015-10-05

    Highlights: • Ga{sub 2}O{sub 3} and YF{sub 3} dual-phase embedded glass ceramics were fabricated. • RE{sup 3+} and Cr{sup 3+} dopants incorporated into YF{sub 3} and Ga{sub 2}O{sub 3} lattice respectively. • Intense blue and red emissions are simultaneously achieved in the sample. • Such glass ceramics had possible application in photosynthesis of plants. - Abstract: A series of γ-Ga{sub 2}O{sub 3} and β-YF{sub 3} nanocrystals embedded dual-phase glass ceramics co-doped with rare earth (Eu{sup 3+} or Tm{sup 3+}) and transition metal (Cr{sup 3+}) activators were successfully prepared by high-temperature melt-quenching to explore blue/red luminescent materials for potential application in photosynthesis of green plants. It is experimentally verified that Eu{sup 3+} (or Tm{sup 3+}) ions partitioned into the crystallized orthorhombic YF{sub 3} nanophases, while Cr{sup 3+} ones entered into the precipitated cubic Ga{sub 2}O{sub 3} nanocrystals after glass crystallization. Such spatial separation of the different active ions in the dual-phase glass ceramics can effectively suppress adverse energy transfers between rare earth and transition metal ions, resulting in their independent and efficient luminescence. As an example, it is experimentally demonstrated that both intense Tm{sup 3+} blue and Cr{sup 3+} deep-red emissions are easily achieved in the Tm{sup 3+}/Cr{sup 3+} co-doped dual-phase glass ceramics.

  2. Enhanced mechanical stability of ultrafine grained steel through intercritical annealing cold rolled martensite

    Institute of Scientific and Technical Information of China (English)

    Huifang LAN; Xianghua LIU; Linxiu DU

    2012-01-01

    The ultrafine grained ferritic steels possess high strength but low ductility due to the shortage of work hardening.Fine grained ferrite-martensite dual phase microstructure was obtained in a microalloyed steel and low carbon steels through intercritical annealing of the cold rolled martensite.The dual phase microstructure was uniform and the ferrite grain size was smaller in the microalloyed steel resulted from the pinning effect of microalloyed precipitates.But ferrite grown apparently and the volume fraction of the martensite was much higher without the addition of microalloying elements.By introducing martensite into the fine grained ferrite,the work hardening was effectively improved,leading to better mechanical stability.As a result of the fine ferrite grain size as well as uniform distribution of the martensite,the work hardening was enhanced,showing better strength-ductility balance in the microalloyed dual phase steel.

  3. Phase analysis of fume during arc weld brazing of steel sheets with protective coatings

    Directory of Open Access Journals (Sweden)

    J. Matusiak

    2016-04-01

    Full Text Available The article presents the results of research of the phase identification and of the quantitative phase analysis of fume generated during Cold Metal Transfer (CMT, ColdArc and Metal Inert Gas / Metal Active Gas (MIG / MAG weld brazing. Investigations were conducted for hot - dip coated steel sheets with zinc (Zn and zinc-iron (Zn - Fe alloy coatings. Arc shielding gases applied during the research-related tests were Ar + O2, Ar + CO2, Ar + H2 and Ar + CO2 + H2 gas mixtures. The analysis of the results covers the influence of the chemical composition of shielding gas on the chemical composition of welding fume.

  4. Long-term stabilization of the optical fiber phase control using dual PID

    Institute of Scientific and Technical Information of China (English)

    WU; Yue; CHEN; Guozhu; SHEN; Yong; ZOU; Hongxin

    2015-01-01

    We propose an approach of long-term stabilization of optical fiber phase by controlling a piezo-based phase modulator and a Peltier component attached to the fiber via a phase-locked loop( PLL) circuit w ith dual proportional-integral- derivative( PID) adjustment. With this approach,we can suppress the fast disturbance and slow drifting of optical fiber to satisfy the requirements of optical phase long-term locking. In theory,a mathematical model of an optical fiber phase control system is established. The disturbance term induced by environment influence is considered into the PLL model. The monotonous and continuous changing environment disturbance w ill cause a steady-state error in this theory model. The experimental results accords w ell w ith the theory. The steady-state performance,adjusting time,and overshoot can be improved by using the dual PID control. As a result,the long-term,highly stable and low noise fiber phase locking is realized experimentally.

  5. An Investigation of the Role of Second Phase Particles in the Design of Ultra High Strength Steels of Improved Toughness

    Science.gov (United States)

    1990-06-20

    examples in the literature. The only example in the literature of blunting to vertices from an initially sharp crack is the blunting of HY80 steel to three...AD-A226 056 AN INVESTIGATION OF THE ROLE OF SECOND PHASE PARTICLES IN THE DESIGN OF ULTRA HIGH STRENGTH STEELS OF IMPROVED TOUGHNESS FINAL REPORT W...THE ROLE OF SECOND PHASE PARTICLES IN THE DESIGN OF ULTRA HIGH STRENGTH STEELS OF IMPROVED TOUGHNESS FINAL REPORT W. M. Garrison, Jr. June 15, 1990 U.S

  6. A tunable and wideband microwave photonic phase shifter based on dual-polarization modulator

    Science.gov (United States)

    Peng, Zhengxue; Wen, Aijun; Gao, Yongsheng; Tu, Zhaoyang

    2017-01-01

    A microwave photonic phase shifter based on dual-polarization Mach-Zehnder modulator (DPol-MZM) is proposed and experimentally demonstrated in this paper. A polarization multiplexed double sideband (DSB) signal is produced by a DPol-MZM. An optical bandpass filter (OBPF) follows after the DPol-MZM to filter out the optical carrier and one sideband. The polarization multiplexed signal is converted into a linear polarization light by a polarizer (Pol), and then beat at a photodiode (PD) to obtain the phase shifted signal. Experiments are carried out, and a continuous phase shift from -180° to 180° over a wide microwave frequency range of 10-33 GHz can be achieved by changing the polarization state using a polarization controller (PC). We also studied the spurious free dynamic range (SFDR) in the experiments. The features of this proposed phase shifter are large operation bandwidth, full-range 360° phase shift, and simple structure.

  7. Can single-phase dual-energy CT reliably identify adrenal adenomas?

    Energy Technology Data Exchange (ETDEWEB)

    Helck, A.; Hummel, N.; Meinel, F.G.; Johnson, T.; Nikolaou, K.; Graser, A. [University of Munich, Institute for Clinical Radiology, Munich (Germany)

    2014-07-15

    To evaluate whether single-phase dual-energy-CT-based attenuation measurements can reliably differentiate lipid-rich adrenal adenomas from malignant adrenal lesions. We retrospectively identified 51 patients with adrenal masses who had undergone contrast-enhanced dual-energy-CT (140/100 or 140/80 kVp). Virtual non-contrast and colour-coded iodine images were generated, allowing for measurement of pre- and post-contrast density on a single-phase acquisition. Adrenal adenoma was diagnosed if density on virtual non-contrast images was ≤10 HU. Clinical follow-up, true non-contrast CT, PET/CT, in- and opposed-phase MRI, and histopathology served as the standard of reference. Based on the standard of reference, 46/57 (80.7 %) adrenal masses were characterised as adenomas or other benign lesions; 9 malignant lesions were detected. Based on a cutoff value of 10 HU, virtual non-contrast images allowed for correct identification of adrenal adenomas in 33 of 46 (71 %), whereas 13/46 (28 %) adrenal adenomas were lipid poor with a density ≥10 HU. Based on the threshold of 10 HU on the virtual non-contrast images, the sensitivity, specificity, and accuracy for detection of benign adrenal lesions was 73 %, 100 %, and 81 % respectively. Virtual non-contrast images derived from dual-energy-CT allow for accurate characterisation of lipid-rich adrenal adenomas and can help to avoid additional follow-up imaging. (orig.)

  8. A mixed ionic and electronic conducting dual-phase membrane with high oxygen permeability.

    Science.gov (United States)

    Fang, Wei; Liang, Fangyi; Cao, Zhengwen; Steinbach, Frank; Feldhoff, Armin

    2015-04-13

    To combine good chemical stability and high oxygen permeability, a mixed ionic-electronic conducting (MIEC) 75 wt% Ce(0.85)Gd(0.1)Cu(0.05)O(2-δ)-25 wt% La(0.6)Ca(0.4)FeO(3-δ)(CGCO-LCF) dual-phase membrane based on a MIEC-MIEC composite has been developed. Copper doping into Ce(0.9)Gd(0.1)O(2-δ) (CGO) oxide enhances both ionic and electronic conductivity, which then leads to a change from ionic conduction to mixed conduction at elevated temperatures. For the first time we demonstrate that an intergranular film with 2-10 nm thickness containing Ce, Ca, Gd, La, and Fe has been formed between the CGCO grains in the CGCO-LCF one-pot dual-phase membrane. A high oxygen permeation flux of 0.70 mL min(-1) cm(-2) is obtained by the CGCO-LCF one-pot dual-phase membrane with 0.5 mm thickness at 950 °C using pure CO2 as the sweep gas, and the membrane shows excellent stability in the presence of CO2 even at lower temperatures (800 °C) during long-term operation.

  9. Simultaneous dual directional strain measurement using spatial phase-shift digital shearography

    Science.gov (United States)

    Wang, Yonghong; Gao, Xinya; Xie, Xin; Wu, Sijing; Liu, Yingxue; Yang, Lianxiang

    2016-12-01

    This paper presents a Dual Directional Sheared Spatial Phase-Shift Digital Shearography (DDS-SPS-DS) system for simultaneous measurement of strains/displacement derivative in two directions. Two Michelson Interferometers are used as the shearing device to create two shearograms, one in the x-shearing direction and one in the y-shearing direction, which are recorded by a single CCD camera. Two lasers with different wavelengths are used for illumination, and corresponding band pass filters are applied in front of each Michelson Interferometer to avoid cross-interference between the two shearing direction channels. Two perpendicular shearing directions in the two measurement channels introduce two different spatial frequency carriers whose spectrums are orientated in different directions after Fourier Transform. Phase maps of the recorded two shearograms can be obtained by applying a windowed inverse Fourier transform, which enables simultaneous measurement of dual directional strains/displacement derivatives. The new system is well suited for nondestructive testing and strain measurement with a continuous or dynamic load. The capability of the dual directional spatial phase-shift digital shearography system is described by theoretical discussions as well as experiments.

  10. Designing dual phase sensing materials from polyaniline filled styrene–isoprene–styrene composites

    Energy Technology Data Exchange (ETDEWEB)

    Sadasivuni, Kishor Kumar, E-mail: kishor_kumars@yahoo.com [Centre for Advanced Materials, Qatar University, Doha (Qatar); Ponnamma, Deepalekshmi [School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686560, Kerala (India); Kasak, Peter; Krupa, Igor; Ali S A Al-Maadeed, Mariam [Centre for Advanced Materials, Qatar University, Doha (Qatar)

    2014-10-15

    The demand for developing oil detectors is ever increasing since the cleanup and recovery from oil spill usually take long time. Here we propose oil sensors made of polyaniline (PANI) filled poly(styrene–isoprene–styrene) (SIS) block copolymer composite films with good uniformity and dispersion. The changes in resistivity of the samples in presence of both oil and water media reveal the good sensing ability of SIS–PANI films towards oil in water (dual phase). The morphology and chemical composition of the developed products are characterized by scanning electron microscopy and Fourier transformation infrared spectroscopy. Swelling studies are performed to correlate the sensing response to the structural variations and based on it a mechanism is derived for the dual phase sensing. Contact angle measurements confirm the behavior further. The thermal properties and crystallinity of the composites are also addressed by the thermogravimetric and differential scanning calorimetric studies. The developed oil sensor material is able to withstand extreme temperature condition as well. - Highlights: • We model a dual phase sensor capable of detecting oil in water. • A mechanism is proposed to correlate sensing with diffusion. • In situ polymerization helps in the uniform distribution of filler. • Polymer composite sensor could be used as stickers on oil pipelines.

  11. Gas-phase hydrogen permeation through alpha iron, 4130 steel, and 304 stainless steel from less than 100 C to near 600 C

    Science.gov (United States)

    Nelson, H. G.; Stein, J. E.

    1973-01-01

    Gas phase hydrogen permeation studies were conducted on hollow, cylindrical membranes of triply zone-refined alpha iron, AISI 304 austenitic stainless steel, and AISI-SAE 4130 steel in both the normalized (ferrite and carbide) and quenched and tempered (martensite) conditions. Membrane temperature was varied from less than 100 C to near 600 C and hydrogen pressure was varied. For one membrane material, normalized 4130 steel, gas phase hydrogen transport under both steady state and nonsteady state conditions was demonstrated to be controlled by lattice diffusion. Additionally, Sievert's law was shown to be applicable. For all membrane materials, expressions for the coefficients for hydrogen permeation were determined by analysis of steady state transport; the coefficients for diffusion were determined by the lag time technique applied to nonsteady state transport; and through a knowledge of the Sievert's constants, the subsurface equilibrium lattice hydrogen concentrations were determined.

  12. Quantitative phase microscopy using dual-plane in-line digital holography.

    Science.gov (United States)

    Das, Bhargab; Yelleswarapu, Chandra S; Rao, D V G L N

    2012-03-20

    We present detailed theoretical evaluation and thorough experimental investigation of quantitative phase imaging using our previously demonstrated dual-plane in-line digital holographic microscopy technique [Opt. Lett. 35, 3426 (2010)]. This evaluation is based on the recording of two interferograms at slightly different planes and numerically reconstructing the object information. The zero-order diffracted wave is eliminated by using the method of subtraction of average intensity of the entire hologram, and the twin-image diffracted wave is removed by Fourier domain processing of the two recorded holograms. Experiments are performed using controlled amplitude and phase objects and human muscle cells to demonstrate the potential of this technique.

  13. Surface coatings on carbon steel for prevention of flow accelerated corrosion under two phase flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Hee-Sang; Kim, Kyung Mo; Hur, Do Haeng [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Seung Hyun; Kim, Ji Hyun [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2015-05-15

    Since the occurrence of a Surry-2 pipe rupture accident, a lot of effort has been made to prevent FAC of carbon steel piping. Some of the chemicals were suggested as a corrosion inhibitor. A platinum decoration was applied as another prevention strategy of carbon steel thinning. The severe FAC-damaged carbon steel pipings were replaced by tolerant materials such as SA335 Gr.P22. However, some components such as the piping materials between moisture separator and turbine have still suffered from the FAC degradation. This work provides a coating method to prevent the FAC degradation of the SA106 Gr.B, which is a piping material between moisture separator and high-pressure turbine, under two-phase flow. We suggested the coating materials to prevent FAC of SA106Gr.B under two-phase water-vapor flow. The FAC resistance of SA106Gr.B was improved with 5 times by electroless-deposited Ni-P protective layer. Other coating materials also enhanced the tolerance up to 5 times for the FAC in a condition of 150 .deg. C and 3.8 bar at 9.5 compared to non-coated SA106Gr.B.

  14. Dual transponder ranging performance in the presence of oscillator phase noise

    Institute of Scientific and Technical Information of China (English)

    赵明臣; 王春晖; 金小军; 金仲和

    2015-01-01

    A dual transponder carrier ranging method can be used to measure inter-satellite distance with high precision by combining the reference and the to-and-fro measurements. Based on the differential techniques, the oscillator phase noise, which is the main error source for microwave ranging systems, can be significantly attenuated. Further, since the range measurements are derived on the same satellite, the dual transponder ranging system does not need a time tagging system to synchronize the two satellites. In view of the lack of oscillator noise analysis on the dual transponder ranging model, a comprehensive analysis of oscillator noise effects on ranging accuracy is provided. First, the dual transponder ranging system is described with emphasis on the detailed analysis of oscillator noise on measurement precision. Then, a high-fidelity numerical simulation approach based on the power spectrum density of an actual ultra-stable oscillator is carried out in both frequency domain and time domain to support the presented theoretical analysis. The simulation results under different conditions are consistent with the proposed concepts, which makes the results reliable. Besides, the results demonstrate that a high level of accuracy can be achieved by using this oscillator noise cancelation-oriented ranging method.

  15. Experimental Determination of the Primary Solidification Phase dependency on the solidification velocity for 17 different austenitic stainless steel compositions

    DEFF Research Database (Denmark)

    Laursen, Birthe Nørgaard; Olsen, Flemming Ove; Yardy, John

    1997-01-01

    When studying laser welding of austenitic stainless steel, hot cracking is frequently observed. To prevent hot cracking in laser welded stainless steel it is advantageous to obtain primary solidification of the ferrite phase that subsequently, on cooling, transforms in the solid state...... to the austenite phase.Most stainless steels are weldable by conventional welding techniques. However, during laser weldng the solidification velocities can be very much higher than by conventional welding techniques. By increasing the solidification velocity to a critical value known as the transition velocity......, the primary solidification phase is found to change from ferrite to austenite.A novel laser remelting technique has been modified to enable the transition velocity for laser welded austenitic stainless steels to be deermined experimentally and on the basis of results from 17 different alloy compositions...

  16. Pancreatic adenocarcinoma: dual-phase helical CT with surgical and histopathologic correlation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun A; Yoon, Kwon Ha; Park, Seong Hoon; Yun, Ki Jung; Won, Jong Jin [Wonkwang University School of Medicine, Iksan (Korea, Republic of)

    2003-03-01

    To determine the accuracy of dual-phase helical CT in assessing the resectability of pancreatic ductal adenocarcinoma, and to correlate the CT findings with the surgical and histopathologic findings. Thirty patients with pathologically proven cancer of the pancreas underwent arterial-and portal-phase helical CT scanning, and in the two of these, single-level dynamic CT was performed during celiac and superior mesenteric arteriography. In 17 patients who underwent surgery for potentially resectable cancer of the pancreatic head, tumor resectability was assessed. The CT findings were analyzed and correlated with these of surgery and histopathology. In 13 (76%) of the 17 patients who underwent surgery, tumors were resectable. Their average size was 2.76 cm (arterial phase), 2.30 cm (portal phase), and 2.48 cm (pathologically determined) and the overall accuracy of helical CT for assessing resectability was 87%. In all patients, the central portion of the tumors exhibited hypoattenuation at both phases; the peripheral portion showed hypoattenuation at the arterial phase and iso- (n=10) or hyperattenuation (n=3) at the portal phase. Single-level dynamic CT depicted a persistently hypoattenuating central portion and progressive and prolonged enhancement of the periphery. CT-histopathologic correlation showed that central hypoattenuation indicated the presence of tumor cells, necrosis (n=3) and mucin (n=4), while the peripheral iso- or hyperattenuated areas seen at the portal phase represented fibrosis and inflammatory infiltration. Histopathologic examination revealed tumoral infiltration of peripancreatic fat tissue (n=11) and microvascular invasion of major peripancreatic vessels (n=7). The dual-phase helical CT is useful in the determination of resectability in pancreas cancer and CT findings represent well the histopathologic features of pancreas cancer.

  17. Direct observations of sigma phase growth and dissolution in 2205 duplex stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, T.A.; Elmer, J.W.; Babu, S.S.; Specht, E.D. (LLNL); (ORNL)

    2007-10-10

    The formation and growth of sigma ({sigma}) phase in a 2205 duplex stainless steel is monitored during an 850 C isothermal heat treatment using an in situ synchrotron x-ray diffraction technique. At this temperature, {sigma} phase is first observed within approximately 40 seconds of the start of the isothermal heat treatment and grows rapidly over the course of the 3600 second heat treatment to a volume fraction of approximately 13%. A simultaneous increase in the austenite ({gamma}) volume fraction and a decrease in the ferrite ({delta}) volume fraction are observed. The {sigma} phase formed at this temperature is rapidly dissolved within approximately 200 seconds when the temperature is increased to 1000 C. Accompanying this rapid dissolution of the {sigma} phase, the {delta} and {gamma} volume fractions both approach the balanced (50/50) level observed in the as-received material.

  18. Numerical model of phase transformation of steel C80U during hardening

    Directory of Open Access Journals (Sweden)

    T. Domański

    2007-12-01

    Full Text Available The article concerns numerical modelling of the phase transformations in solid state hardening of tool steel C80U. The transformations were assumed: initial structure – austenite, austenite – perlite, bainite and austenite – martensite. Model for evaluation of fractions of phases and their kinetics based on continuous heating diagram (CHT and continuous cooling diagram (CCT. The dilatometric tests on the simulator of thermal cycles were performed. The results of dilatometric tests were compared with the results of the test numerical simulations. In this way the derived models for evaluating phase content and kinetics of transformations in heating and cooling processes were verified. The results of numerical simulations confirm correctness of the algorithm that were worked out. In the numerical example the simulated estimation of the phase fraction in the hardened axisimmetrical element was performed.

  19. Using Phased Array Ultrasonic Testing in Lieu of Radiography for Acceptance of Carbon Steel Piping Welds

    Energy Technology Data Exchange (ETDEWEB)

    Moran, Traci L.; Anderson, Michael T.; Cinson, Anthony D.; Crawford, Susan L.; Nove, Carol A.

    2014-08-01

    The Pacific Northwest National Laboratory (PNNL) is conducting studies for the U.S. Nuclear Regulatory Commission (NRC) to assess the capability, effectiveness, and reliability of ultrasonic testing (UT) as a replacement method for radiographic testing (RT) for volumetric examination of nuclear power plant (NPP) components. This particular study focused on evaluating the use of UT on carbon steel plate welds. Welding fabrication flaws included a combination of planar and volumetric types, e.g., incomplete fusion, lack of penetration, cracks, porosity, and slag inclusions. The examinations were conducted using phased-array (PA) UT techniques applied primarily for detection and flaw type characterization. This paper will discuss the results of using UT in lieu of RT for detection and classification of fabrication flaws in carbon steel plate welds.

  20. Simulation and experiment for the inspection of stainless steel bolts in servicing using an ultrasonic phased array

    Science.gov (United States)

    Chen, Jinzhong; He, Renyang; Kang, Xiaowei; Yang, Xuyun

    2015-10-01

    The non-destructive testing of small-sized (M12-M20) stainless steel bolts in servicing is always a technical problem. This article focuses on the simulation and experimental research of stainless steel bolts with an artificial defect reflector using ultrasonic phased array inspection. Based on the observation of the sound field distribution of stainless steel bolts in ultrasonic phased array as well as simulation modelling and analysis of the phased array probes' detection effects with various defect sizes, different artificial defect reflectors of M16 stainless steel bolts are machined in reference to the simulation results. Next, those bolts are tested using a 10-wafer phased array probe with 5 MHz. The test results finally prove that ultrasonic phased array can detect 1-mm cracks in diameter with different depths of M16 stainless steel bolts and a metal loss of Φ1 mm of through-hole bolts, which provides technical support for future non-destructive testing of stainless steel bolts in servicing.

  1. Microstructure and mechanical properties of nonmagnetic Fe-25Mn-xCu-C steels by super solidus liquid phase sintering

    Science.gov (United States)

    Jia, Shanquan; Xiao, Zhiyu; Wang, Jun; Yang, Shuo; Guan, Hangjian; Zhu, Quanli

    2016-11-01

    In this work, nonmagnetic steels Fe-25Mn-xCu-C were prepared by high manganese pre-alloyed steel powders through powder metallurgy (PM) technique. Four types of steels specimen were created to investigate the microstructure evolving with sintering process, mechanical properties and magnetic properties. The microstructures, fracture surfaces, phase constitutions and mechanical properties of Fe-25Mn-xCu-C were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), and tensile strength test. The results showed that super solidus liquid-phase sintering (SLPS) phenomenon was conclusively verified, for the first time, in the Fe-Mn pre-alloyed powders: Liquids generated by SLPS process from pre-alloyed powders could improve the binding condition between the particles and enhance the densification. X-ray diffraction (XRD) experiment and physical property measurement system (PPMS) measurement verified the nonmagnetic properties of steels with single austenite phase. It is confirmed that mechanical properties are intensively influenced by the characteristic and quantity of liquids between the matrix particles. The fracture mechanism of the steel is dominated by intergranular decohesion mode. The preliminary study found this kind of new non-magnetic steel exhibits relatively high density. With the efficiency in fabricating and the non-magnetic property, this work foresees good prospects for application in the steel components manufacturing industry.

  2. Inductive resistivity logging in steel-cased boreholes. SBIR Phase 2 progress report

    Energy Technology Data Exchange (ETDEWEB)

    Wilt, M.

    1999-07-01

    SBIR Phase 2 project 40145-97-I calls for the design and construction of a prototype inductive logging device to measure formation resistivity from within a steel-cased borehole. The SCIL (Steel Casing Induction Logger) tool is intended for reservoir characterization and process monitoring in an oil field environment. This report summarizes findings from the initial project period. In this phase, bench model measurements were made to test casing compensation schemes, numerical models were calculated to optimize the tool configuration and associated formation sensitivity and the preliminary design of the tool was completed. The bench tests constitute fundamental research on determining the characteristics of steel well casing and on developing means of separating the effects of the casing and the formation. This technology is crucial to the success of the project and significant progress has been made towards the goal of recovering the formation resistivity from inside the casing. Next, a series of sensitivity and tool configuration studies have been completed through partner Dr. David Alumbaugh at Sandia National Laboratories. These numerical results help to optimize the tool configuration and allow one to calculate the expected formation sensitivity. These models are preliminary to data interpretation software to be developed in the next project period. The initial hardware design of the tool has been completed, and ordering parts has begun for later manufacture and assembly. The tool, which is designed for maximum flexibility of deployment, will have a powerful transmitter, an array of three component sensors and sufficient dynamic range to operate in standard oil field steel-cased boreholes.

  3. Preliminary Research on Dual-Energy X-Ray Phase-Contrast Imaging

    CERN Document Server

    Han, Huajie; Gao, Kun; Wang, Zhili; Zhang, Can; Yang, Meng; Zhang, Kai; Zhu, Peiping

    2015-01-01

    Dual-energy X-ray absorptiometry (DEXA) has been widely applied to measure bone mineral density (BMD) and soft-tissue composition of human body. However, the use of DEXA is greatly limited for low-Z materials such as soft tissues due to their weak absorption. While X-ray phase-contrast imaging (XPCI) shows significantly improved contrast in comparison with the conventional standard absorption-based X-ray imaging for soft tissues. In this paper, we propose a novel X-ray phase-contrast method to measure the area density of low-Z materials, including a single-energy method and a dual-energy method. The single-energy method is for the area density calculation of one low-Z material, while the dual-energy method is aiming to calculate the area densities of two low-Z materials simultaneously. Comparing the experimental and simulation results with the theoretic ones, the new method proves to have the potential to replace DEXA in area density measurement. The new method sets the prerequisites for future precise and lo...

  4. Differential diagnosis of Parkinsonism using dual phase F 18 FP CIT PET imaging

    Energy Technology Data Exchange (ETDEWEB)

    Jin, So Young; Oh, Min Young; Ok, Seung Jun; Oh, Jung Su; Lee, Sang Ju; Chung, Sun Ju; Lee, Chong Sik; Kim, Jae Seung [Univ. of Ulsan, Seoul (Korea, Republic of)

    2012-03-15

    Dopamine transporter (DAT) imaging can demonstrate presynaptic dopaminergic neuronal loss in Parkinson's disease (PD). However, differentiating atypical parkinsonism (APD) from PD is often difficult. We investigated the usefulness of dual phase F 18 FP CIT positron emission tomography (PET) imaging in the differential diagnosis of parkinsonism. Ninety eight subjects [five normal, seven drug induced parkinsonism (DIP), five essential tremor (ET), 24 PD, 20 multiple system atrophy parkinson type (MSA-P), 13 multiple system atrophy cerebellar type (MSA-C), 13 progressive supranuclear palsy (PSP), and 11 dementia with Lewy bodies(DLB)] underwent F 18 FP CIT PET. PET images were acquired at 5 min (early phase) and 3 h (late phase) after F 18 FP CIT administration (185MBq). Regional uptake pattern of cerebral and cerebellar hemispheres was assessed on early phase images, using visual, quantitative, and statistical parametric mapping (SPM) analyses. Striatal DAT binding was normal in normal, ET, DIP, and MSA C groups, but abnormal in PD, MSA P PSP, and DLB groups. No difference was found in regional uptake on early phase images among normal DAT binding groups, except in the MSA C group. Abnormal DAT binding groups showed different regional uptake pattern on early phase images compared with PD in SPM analysis (FDR<0.05). When discriminating APD from PD, visual interpretation of the early phase image showed high diagnostic sensitivity and specificity (75.4% and 100%, respectively). Regarding the ability to distinguish specific APD, sensitivities were 81% for MSA P, 77% for MSA C, 23% for PSP, and 54.5% for DLB. Dual phase F 18 FP CIT PET imaging is useful in demonstrating striatal DAT loss in neurodegenerative parkinsonism, and also in differentiating APD, particularly MSA, from PD.

  5. Measuring laves phase particle size and thermodynamic calculating its growth and coarsening behavior in P92 steels

    DEFF Research Database (Denmark)

    Yao, Bing-Yin; Zhou, Rong-Can; Fan, Chang-Xin;

    2010-01-01

    ) images in scanning electron microscope (SEM). The smaller Laves phase particle size results in higher creep strength and longer creep exposure time at the same conditions. DICTRA software was used to model the growth and coarsening behavior of Laves phase in the three P92 steels. Good agreements were......The growth of Laves phase particles in three kinds of P92 steels were investigated. Laves phase particles can be easily separated and distinguished from the matrix and other particles by atom number contrast using comparisons of the backscatter electrons (BSE) images and the secondary electrons (SE...... attained between measurements in SEM and modeling by DICTRA. Ostwald ripening should be used for the coarsening calculation of Laves phase in P92 steels for time longer than 20000 h and 50000 h at 650°C and 600°C, respectively. © 2010 Chin. Soc. for Elec. Eng....

  6. DC-bias Cancellation for Phase Shift Controlled Dual Active Bridge

    DEFF Research Database (Denmark)

    Alzola, Rafael Pena; Mathe, Laszlo; Liserre, Marco;

    2013-01-01

    The dual active bridge topology allows bidirectional power flow and galvanic isolation for DC/DC energy conversion. These features have made it the possible backbone of the future smart transformer for distribution. The different voltage drops and commutation dead-times of the semiconductor...... switches result in DC-voltage at the transformer terminals. Even small DCvoltage components produce large DC-bias currents as they are only limited by the transformer resistances. The DC-bias degrades the transformer performance by increasing the losses. If the core saturates the resulting current pulses...... can damage the converter. A typical approach to avoid the DC-bias is placing a capacitor in series with the transformer. This capacitor suffers large current variations, reducing its reliability, and complicates the control. The dual active bridge usually handles the power flow by modifying the phase...

  7. Dual-phase dual-energy CT in patients with lung cancer: assessment of the additional value of iodine quantification in lymph node therapy response

    Energy Technology Data Exchange (ETDEWEB)

    Baxa, Jan; Vondrakova, Alena; Matouskova, Tana; Ferda, Jiri [Charles University Teaching Hospital Plzen, Department of Imaging Methods, Plzen (Czech Republic); Ruzickova, Olga [Charles University Teaching Hospital Plzen, Department of Pulmonary Diseases, Plzen (Czech Republic); Schmidt, Bernhard; Flohr, Thomas; Sedlmair, Martin [Siemens Healthcare, CT Physics and Applications Development, Forchheim (Germany)

    2014-08-15

    To investigate the potential contribution of iodine uptake calculation from dual-phase dual-energy CT (DE-CT) for lymph node staging and therapy response monitoring in lung cancer patients. Retrospective analysis of 27 patients with non-small cell lung carcinoma (NSCLC), who underwent dual-phase DE-CT before and after chemotherapy, was performed. Iodine uptake (mg/mL) and total iodine uptake (mg) were calculated using prototype software in the early (arterial) and late (venous) post-contrast circulatory phase in 110 mediastinal lymph nodes. The arterial enhancement fraction (AEF) was calculated and compared with lymph node size and response to chemotherapy. A significant difference of AEF was observed between enlarged (90.4 %; 32.3-238.5 %) and non-enlarged (72.7 %; -37.5-237.5 %) lymph nodes (p = 0.044) before treatment onset. A significantly different change of AEF in responding (decrease of 26.3 %; p = 0.022) and non-responding (increase of 43.0 %; p = 0.031) lymph nodes was demonstrated. A higher value of AEF before treatment was observed in lymph nodes with subsequent favourable response (88.6 % vs. 77.7 %; p = 0.122), but this difference did not reach statistical significance. The dual-phase DE-CT examination with quantification of ratio of early and late post-contrast iodine uptake is a feasible and promising method for the functional evaluation of mediastinal lymph nodes including therapy response assessment. (orig.)

  8. Phase-dependent dual-frequency contrast imaging at sub-harmonic frequency.

    Science.gov (United States)

    Shen, Che-Chou; Cheng, Chih-Hao; Yeh, Chih-Kuang

    2011-02-01

    Sub-harmonic imaging techniques have been shown to provide a higher contrast-to-tissue ratio (CTR) at the cost of relatively low signal intensity from ultrasound contrast agents (UCAs). In this study, we propose a method of dual-frequency excitation to further enhance the CTR of subharmonic imaging. A dual-frequency excitation pulse is an amplitude-modulated waveform which consists of two sinusoids with frequencies of f₁ (e.g., 9 MHz) and f₂ (e.g., 6 MHz) and the resulting envelope component at (f₁ - f₂) (e.g., 3 MHz) can serve as a driving force to excite the nonlinear response of UCAs. In this study, the f₂, at twice of the resonance frequency of UCAs, is adopted to efficiently generate a sub-harmonic component at half of the f₂ frequency, and f₁ is included to enhance the high-order nonlinear response of UCAs at the sub-harmonic frequency. The second- and third-order nonlinear components resulting from the envelope component would spectrally overlap at the sub-harmonic frequency when f₁ and f₂ are properly selected. We further optimize the generation of the sub-harmonic component by tuning the phase terms between second- and third-order nonlinear components. The results show that, with dual-frequency excitation, the CTR at sub-harmonic frequency improves compared with the conventional tone-burst method. Moreover, the CTR changes periodically with the relative phase of the separate frequency component in the dual-frequency excitation, leading to a difference of as much as 9.1 dB between the maximal and minimal CTR at 300 kPa acoustic pressure. The echo produced from the envelope component appears to be specific for UCAs, and thus the proposed method has the potential to improve both SNR and CTR in sub-harmonic imaging. Nevertheless, the dual-frequency waveform may suffer from frequency-dependent attenuation that degrades the generation of the envelope component. The deviation of the microbubble's resonance characteristics from the selection of

  9. Aging-related decrements during specific phases of the dual-task Timed Up-and-Go test.

    Science.gov (United States)

    Porciuncula, Franchino S; Rao, Ashwini K; McIsaac, Tara L

    2016-02-01

    It is unclear how young and older adults modulate dual-task mobility under changing postural challenges. To examine age-related changes in dual-task processing during specific phases of dual-task Timed Up-and-Go (TUGdual-task). Healthy young and older adults performed the Timed Up-and-Go (TUG) with the following dual-task conditions: (1) serial-three subtractions, (2) carrying cup of water, (3) combined subtraction and carrying water, and (4) dialing cell phone. The primary outcome was the dual-task cost on performance of TUG (percent change from single- to dual-task) based on duration and peak trunk velocity of each phase: (a) straight-walk, (b) sit-to-stand, (c) turn, (d) turn-to-sit. Mixed-design univariate analysis of variance was performed for each type of task. Older adults had more pronounced mobility decrements than young adults during straight-ahead walking and turns when the secondary task engaged both cognitive and manual modalities. Simple cognitive or manual tasks during TUGdual-task did not differentiate young from older participants. Subtraction performance during simple and complex cognitive conditions differed by phase of the TUG. Manual task performance of carrying water did not vary by phase or age. Our findings suggest that dual-task processing is dynamic across phases of TUGdual-task. Aging-related dual-task decrements are demonstrated during straight-ahead walking and turning, particularly when the secondary task is more complex. Older adults are susceptible to reduced dual-task mobility during straight-ahead walking and turning particularly when attentional loading was increased.

  10. Microstructural Developments Leading to New Advanced High Strength Sheet Steels: A Historical Assessment of Critical Metallographic Observations

    Energy Technology Data Exchange (ETDEWEB)

    Matlock, David K [CSM/ASPPRC; Thomas, Larrin S [CSM/ASPPRC; Taylor, Mark D [CSM/ASPPRC; De Moor, Emmanuel [CSM/ASPPRC; Speer, John G [CSM/ASPPRC

    2015-08-03

    In the past 30+ years significant advancements have been made in the development of higher strength sheet steels with improved combinations of strength and ductility that have enabled important product improvements leading to safer, lighter weight, and more fuel efficient automobiles and in other applications. Properties of the primarily low carbon, low alloy steels are derived through careful control of time-temperature processing histories designed to produce multiphase ferritic based microstructures that include martensite and other constituents including retained austenite. The basis for these developments stems from the early work on dual-phase steels which was the subject of much interest. In response to industry needs, dual-phase steels have evolved as a unique class of advanced high strength sheet steels (AHSS) in which the thermal and mechanical processing histories have been specifically designed to produce constituent combinations for the purpose of simultaneously controlling strength and deformation behavior, i.e. stress-strain curve shapes. Improvements continue as enhanced dual-phase steels have recently been produced with finer microstructures, higher strengths, and better overall formability. Today, dual phase steels are the primary AHSS products used in vehicle manufacture, and several companies have indicated that the steels will remain as important design materials well into the future. In this presentation, fundamental results from the early work on dual-phase steels will be reviewed and assessed in light of recent steel developments. Specific contributions from industry/university cooperative research leading to product improvements will be highlighted. The historical perspective provided in the evolution of dual-phase steels represents a case-study that provides important framework and lessons to be incorporated in next generation AHSS products.

  11. Phase calibration of sonar systems using standard targets and dual-frequency transmission pulses.

    Science.gov (United States)

    Islas-Cital, Alan; Atkins, Philip R; Foo, Kae Y; Picó, Ruben

    2011-10-01

    The phase angle component of the complex frequency response of a sonar system operating near transducer resonance is usually distorted. Interpretation and classification of the received sonar signal benefits from the preservation of waveform fidelity over the full bandwidth. A calibration process that measures the phase response in addition to the amplitude response is thus required. This paper describes an extension to the standard-target calibration method to include phase angle, without affecting the experimental apparatus, by using dual-frequency transmission pulses and frequency-domain data processing. This approach reduces the impact of unknown range and sound speed parameters upon phase calibration accuracy, as target phase is determined from the relationship of the two frequency components instead of relying on a local phase reference. Tungsten carbide spheres of various sizes were used to simultaneously calibrate the amplitude and phase response of an active sonar system in a laboratory tank. Experimental measurements of target phase spectra are in good agreement with values predicted from a theoretical model based upon full-wave analysis, over an operating frequency of 50-125 kHz.

  12. Measurement of in-plane strain with dual beam spatial phase-shift digital shearography

    Science.gov (United States)

    Xie, Xin; Chen, Xu; Li, Junrui; Wang, Yonghong; Yang, Lianxiang

    2015-11-01

    Full-field in-plane strain measurement under dynamic loading by digital shearography remains a big challenge in practice. A phase measurement for in-plane strain information within one time frame has to be achieved to solve this problem. This paper presents a dual beam spatial phase-shift digital shearography system with the capacity to measure phase distribution corresponding to in-plane strain information within a single time frame. Two laser beams with different wavelengths are symmetrically arranged to illuminate the object under test, and two cameras with corresponding filters, which enable simultaneous recording of two shearograms, are utilized for data acquisition. The phase information from the recorded shearograms, which corresponds to the in-plane strain, is evaluated by the spatial phase-shift method. The spatial phase-shift shearography system realizes a measurement of the in-plane strain through the introduction of the spatial phase-shift technique, using one frame after the loading and one frame before loading. This paper presents the theory of the spatial phase-shift digital shearography for in-plane strain measurement and its derivation, experimental results, and the technique’s potential.

  13. Influence of Laser Peening on Phase Transformation and Corrosion Resistance of AISI 321 steel

    Science.gov (United States)

    Karthik, D.; Swaroop, S.

    2016-07-01

    The objective of this study is to investigate the influence of laser peening without coating (LPwC) on austenitic to martensitic (γ → α') phase transformation and corrosion behavior of austenitic stainless steel AISI 321 in 3.5% NaCl environment. Results indicate that LPwC induces a large compressive residual stresses of nearly -854 MPa and γ → α' phase transformation of about 18% (volume fraction). Microstructures of peened surface confirmed the γ → α' phase transformation and showed no grain refinement. Hardness increased slightly with a case depth of 900 μm. Despite the smaller surface roughness introduced, corrosion resistance improved after peening due to compressive residual stresses.

  14. Core-Shell Structure of Intermediate Precipitates in a Nb-Based Z-Phase Strengthened 12% Cr Steel.

    Science.gov (United States)

    Rashidi, Masoud; Andrén, Hans-Olof; Liu, Fang

    2017-04-01

    In creep resistant Z-phase strengthened 12% Cr steels, MX (M=Nb, Ta, or V, and X=C and/or N) to Z-phase (CrMN, M=Ta, Nb, or V) transformation plays an important role in achieving a fine distribution of Z-phase precipitates for creep strengthening. Atom probe tomography was employed to investigate the phase transformation in a Nb-based Z-phase strengthened trial steel. Using iso-concentration surfaces with different concentration values, and subtracting the matrix contribution enabled us to reveal the core-shell structure of the transient precipitates between MX and Z-phase. It was shown that Z-phase forms by diffusion of Cr into NbN upon ageing, and Z-phase has a composition corresponding to Cr1+x Nb1-x N with x=0.08.

  15. Austenite phase formation in rapidly solidified Fe-Cr-Mn-C steels

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S.R.; Davies, H.A.; Rainforth, W.M.

    1999-12-10

    Steels having compositions (wt%) 0.05--0.5C, 12.5--20Cr, 8--25Mn and 0--0.51N have been chill-block melt-spun to ribbons in order to investigate systematically, by X-ray diffractometry and electron microscopy, the effects of rapid solidification and of solute concentrations on the formation of the austenite phase. The austenite is most easily formed at (wt%) 16Cr--8Mn for 0.3C ribbons while {alpha}{prime}-martensite or {epsilon}-martensite was observed at lower concentrations of Cr or Mn and {alpha}-ferrite appeared for Cr {gt} 18 wt%. The volume fraction of austenite in the steel ribbons studied was found, by multiple regression analysis, to obey the equation {gamma}(%) = 94 + 26.8C + Mn x (8.4 {minus} 0.08Mn {minus} 0.44Cr) {minus} (Cr {minus} 17.7){sup 2}. Thus, the effect of Mn on {gamma} formation followed a non-linear function, containing an interaction term including the Cr and Mn contents, and first- and second-order terms involving the Mn concentration. This indicates the ranges over when Mn is a {gamma}-former or an {alpha}-former. Iso-austenitic lines, constructed on the basis of this new equation, are nearly orthogonal to those in the Schaeffler diagram for Cr-Mn steels so that use of the latter for prediction of the austenite content in the present case would be inappropriate.

  16. Third Generation 0.3C-4.0Mn Advanced High Strength Steels Through a Dual Stabilization Heat Treatment: Austenite Stabilization Through Paraequilibrium Carbon Partitioning

    Science.gov (United States)

    Qu, Hao; Michal, Gary M.; Heuer, Arthur H.

    2014-06-01

    In excess of 30 vol. pct austenite can be retained in 0.3C-4.0Mn steels subjected to a dual stabilization heat treatment (DSHT) schedule—a five stage precisely controlled cooling schedule that is a variant of the quench and partition process. The temperature of the second quench (stage III) in the DSHT process plays an essential role in the retained austenite contents produced at carbon-partitioning temperatures of 723 K or 748 K (450° C or 475 °C) (stage IV). A thermodynamic model successfully predicted the retained austenite contents in heat-treated steels, particularly for a completely austenitized material. The microstructure and mechanical behavior of two heat-treated steels with similar levels of retained austenite (~30 vol. pct) were studied. Optimum properties—tensile strengths up to 1650 MPa and ~20 pct total elongation—were observed in a steel containing 0.3C-4.0Mn-2.1Si, 1.5 Al, and 0.5 Cr.

  17. Phase transformation and long-term service of high-temperature martensitic chromium steels

    Science.gov (United States)

    Kalashnikov, I. S.; Tarasenko, L.; Acselrad, O.; Pereira, L. C.; Shalkevich, A.; Soboleva, G.

    2001-02-01

    Martensitic high Cr (10 - 16%) steels alloyed with Ni (Co), Mo, W, V, and N are widely used in constructions subjected to cyclic loads at temperatures up to 600 degrees Celsius, in general after quenching from 1100 - 1150 degrees Celsius followed by tempering at 650 - 690 degrees Celsius. Due to long term service exposure at high temperatures, different microstructural changes take place, such as second-phases precipitation, formation of low-angle grain boundaries, as well as internal damage caused by cyclic loads and creep. Specific phase diagrams are presented that can be used to define time periods for reliable operation of parts with given composition, based on the time required for the appearance of second phase particles known to be detrimental to mechanical strength and performance. Restoring thermal treatments to be applied after long time exposure at service conditions, aiming at increasing service life, are also presented and discussed. The combined use of the diagrams and the restoring treatment ensures prediction of a reliable service-life period for components made of these steels.

  18. Moessbauer characterization of joints of steel pieces in transient liquid phase bonding experiences

    Energy Technology Data Exchange (ETDEWEB)

    Di Luozzo, N.; Martinez Stenger, P. F.; Canal, J. P.; Fontana, M. R.; Arcondo, B., E-mail: barcond@fi.uba.ar [INTECIN (UBA-CONICET), Laboratorio de Solidos Amorfos, Facultad de Ingenieria (Argentina)

    2011-11-15

    Joining of seamless, low carbon, steel tubes were performed by means of Transient Liquid Phase Bonding process employing a foil of Fe-Si-B metallic glass as filler material. The influence of the main parameters of the process was evaluated: temperature, holding time, pressure and post weld heat treatment. Powder samples were obtained from the joint of tubes and characterized employing Moessbauer Spectroscopy in transmission geometry. The sampling was performed both in tubes successfully welded and in those which show joint defects. The results obtained are correlated with the obtained microstructure and the diffusion of Si and B during the process.

  19. The effect of thermal cycle on joint of Ti/stainless steel phase transformation diffusion bonding

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effects of thermal cycle parameters on the tensile strength and fracture characteristics of phase transformation diffusion bonding(PTDB) joint of titanium and stainless steel (Ti/SS) were studied in this paper. With the maximum cyclic temperature of 1173~1223K, the minimum cyclic temperature of 1073~1093K, the heating velocity of 30~50K/s, the cooling velocity of 15~20K/s , the cycle numbers of 15~20 and bonding pressure is 13MPa, the tensile strength of joint is more than 380MPa, exceeding 80% of that of Ti.

  20. A constitutive model for the anelastic behavior of Advanced High Strength Steels

    NARCIS (Netherlands)

    Torkabadi, A.; Liempt, van P.; Meinders, V.T.; Boogaard, van den A.H.

    2015-01-01

    In this work a physically based model describing the anelastic behaviour and nonlinear unloading in Advanced High Strength Steels (AHSS) is proposed. The model is fitted to the experimental data obtained from uni-axial tests on a dual-phase high strength steel grade (HCT780). The results show a good

  1. Early-stage Widmanstaetten growth of the {gamma} phase in a duplex steel

    Energy Technology Data Exchange (ETDEWEB)

    Shek, C.H.; Dong, C.; Lai, J.K.L.; Wong, K.W.

    2000-01-01

    The present work studies the Widmanstaetten {gamma}-phase morphology and crystallographic orientation relationships with ferrite during its initial-stage growth in a duplex steel. Transmission electron microscopy (TEM) and convergent-beam electron diffraction (CBED) analyses have been applied to determine the orientation relationship with high precision. When the secondary {gamma} phase and the {alpha} phase have special orientation relationships close to the K-S (Kurdjumov-Sachs) relation, the preferential growth involves {gamma} phase, protruding into {alpha} phase and this leads, finally, to the formation of Widmanstatten needles. The needles grow nearly along the invariant-line direction, but they do not satisfy exactly the K-S relation, and a slight angular deviation ({theta}{sub [110]{alpha}}) is always present. This deviation is explained by a compromise between the well-known invariant-line condition, which offers the easiest way for directional growth of the {gamma} phase, and a good atomic matching of the close-packed (1{ovr 11}){gamma} and (110){sub {alpha}} planes of both phases. A matching minimum at {theta}{sub [110]{alpha}} = 2.3 deg is obtained when only three pairs of the nearest-neighbor atoms are considered in an atomic misfit calculation.

  2. Application of thermal wave imaging and phase shifting method for defect detection in Stainless steel

    Science.gov (United States)

    Shrestha, Ranjit; Park, Jeonghak; Kim, Wontae

    2016-05-01

    This paper presents an experimental arrangement for detection of artificial subsurface defects in a stainless steel sample by means of thermal wave imaging with lock-in thermography and consequently, the impact of excitation frequency on defect detectability. The experimental analysis was performed at several excitation frequencies to observe the sample beginning from 0.18 Hz all the way down to 0.01 Hz. The phase contrast between the defective and sound regions illustrates the qualitative and quantitative investigation of defects. The two, three, four and five-step phase shifting methods are investigated to obtain the information on defects. A contrast to noise ratio analysis was applied to each phase shifting method allowing the choice of the most appropriate one. Phase contrast with four-step phase shifting at an optimum frequency of 0.01 Hz provides excellent results. The inquiry with the effect of defect size and depth on phase contrast shows that phase contrast decreases with increase in defect depth and increases with the increase in defect size.

  3. The use of dual-phase {sup 18}F-FDG PET in characterizing thyroid incidentalomas

    Energy Technology Data Exchange (ETDEWEB)

    Hsiao, Y.-C.; Wu, P.-S.; Chiu, N.-T.; Yao, W.-J. [Department of Nuclear Medicine, National Cheng Kung University Medical College and Hospital, Tainan, Taiwan (China); Lee, B.-F., E-mail: bflee@mail.ncku.edu.tw [Department of Nuclear Medicine, National Cheng Kung University Medical College and Hospital, Tainan, Taiwan (China); Peng, S.-L. [Department of Pathology, National Cheng Kung University Medical College and Hospital, Tainan, Taiwan (China)

    2011-12-15

    Aim: To examine the usefulness of dual-phase 2-[{sup 18}F]-fluoro-2-deoxy-D-glucose (FDG) positron-emission tomography (PET) for the evaluation of thyroid incidentalomas. Materials and methods: In this retrospective study, cases with focal thyroid lesions seen incidentally at FDG PET in which the histopathological diagnosis was available and in which dual-phase FDG PET imaging was performed at 1 and 2 h after FDG injection were reviewed. In the included cases, the 1 and 2 h maximal standard uptake value (1-hour maximal SUV and 2-hour maximal SUV, respectively) and retention index (RI) were calculated, and the differences between benign and malignant thyroid incidentalomas were analysed. Receiver operating characteristic (ROC) analysis was performed to evaluate the ability of 1-hour maximal SUV, 2-hour maximal SUV, and RI to discriminate benign from malignant lesions. Results: A total of 39 patients (25 females, 14 males) with 45 lesions (17 malignant, 28 benign) were included. In malignant thyroid incidentalomas, the average 1-hour maximal SUV, 2-hour maximal SUV, and RI were 5.20, 5.72, and 7.67%, respectively, and in benign thyroid incidentalomas the values were 4.67, 4.97, and 7.38%, respectively. There were no significant differences in 1-hour maximal SUV, 2-hour maximal SUV, and RI between benign and malignant lesions. The area under the ROC curve did not differ from 0.5. Conclusion: Dual-phase FDG PET is not useful for differentiating benign from malignant thyroid incidentalomas.

  4. The National Shipbuilding Research Program. Automated Process Application in Steel Fabrication and Subassembly Facilities; Phase I (Process Analysis)

    Science.gov (United States)

    1999-05-01

    6 Automated Process Application in Steel Fabrication and Subassembly Facilities; Phase I ( Process Analysis ) U.S. DEPARTMENT OF THE NAVY CARDEROCK...Subassembly Facilities; Phase I ( Process Analysis ) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e

  5. Lens-free and portable quantitative phase microscope using a dual-pinhole aperture

    OpenAIRE

    Lu Yujie; Liu Yunhui; Wang Zerui; Zheng Fan

    2015-01-01

    This paper presents a lens-free and portable quantitative phase microscope. This microscope employs a concise off-axis set-up where a dual-pinhole aperture is utilized to generate the reference wave and the object wave. As no lenses or beamsplitters are used in this microscope, the total size of this microscope is only slightly larger than a smart phone, and the cost of this microscope except for the digital camera is about 3000 RMB. Even with such small size and low cost, this microscope pos...

  6. Lens-free and portable quantitative phase microscope using a dual-pinhole aperture

    Directory of Open Access Journals (Sweden)

    Lu Yujie

    2015-01-01

    Full Text Available This paper presents a lens-free and portable quantitative phase microscope. This microscope employs a concise off-axis set-up where a dual-pinhole aperture is utilized to generate the reference wave and the object wave. As no lenses or beamsplitters are used in this microscope, the total size of this microscope is only slightly larger than a smart phone, and the cost of this microscope except for the digital camera is about 3000 RMB. Even with such small size and low cost, this microscope possesses a lateral resolution of ~ 1:7μm and an axial accuracy of tens of nanometers.

  7. Dual random phase encoding: a temporal approach for fiber optic applications.

    Science.gov (United States)

    Cuadrado-Laborde, Christian; Duchowicz, Ricardo; Torroba, Roberto; Sicre, Enrique E

    2008-04-10

    We analyze the dual random phase encoding technique in the temporal domain to evaluate its potential application for secure data transmission in fiber optic links. To take into account the optical fiber multiplexing capabilities, the noise content of the signal is restricted when multiple channels are transmitted over a single fiber optic link. We also discuss some mechanisms for producing encoded time-limited as well as bandwidth-limited signals and a comparison with another recently proposed technique is made. Numerical simulations have been carried out to analyze the system performance. The results indicate that this multiplexing encryption method could be a good alternative compared with other well-established methods.

  8. Dual strain mechanisms in a lead-free morphotropic phase boundary ferroelectric

    DEFF Research Database (Denmark)

    Walker, Julian; Simons, Hugh; Alikin, Denis O;

    2016-01-01

    )-based ferroelectric ceramics. In the search for Pb-free alternatives, systems with MPBs between polar and non-polar phases have recently been theorized as having great promise. While such an MPB was identified in rare-earth (RE) modified bismuth ferrite (BFO) thin films, synthesis challenges have prevented its...... realization in ceramics. Overcoming these, we demonstrate a comparable electromechanical response to Pb-based materials at the polar-to-non-polar MPB in Sm modified BFO. This arises from 'dual' strain mechanisms: ferroelectric/ferroelastic switching and a previously unreported electric-field induced...

  9. High temperature phase chemistries and solidification mode prediction in nitrogen-strengthened austenitic stainless steels

    Science.gov (United States)

    Ritter, Ann M.; Henry, Michael F.; Savage, Warren F.

    1984-07-01

    Nitronic 50 and Nitronic 50W, two nitrogen-strengthened stainless steels, were heat treated over a wide range of temperatures, and the compositions of the ferrite and austenite at each temperature were measured with analytical electron microscopy techniques. The compositional data were used to generate the (γ + δ phase field on a 58 pct Fe vertical section. Volume fractions of ferrite and austenite were calculated from phase chemistries and compared with volume fractions determined from optical micrographs. Weld solidification modes were predicted by reference to the Cr and Ni contents of each alloy, and the results were compared with predictions based on the ratios of calculated Cr and Ni equivalents for the alloys. Nitronic 50, which contained ferrite and austenite at the solidus temperature of 1370 °C, solidified through the eutectic triangle, and the weld microstructure was similar to that of austenitic-ferritic solidification. Nitronic 50W was totally ferritic at 1340 °C and solidified as primary delta ferrite. During heat treatments, Nitronic 50 and Nitronic 50W precipitated secondary phases, notably Z-phase (NbCrN), sigma phase, and stringered phases rich in Mn and Cr.

  10. Photoemission Electron Microscopy as a Tool for Studying Steel Grains

    Science.gov (United States)

    Roese, Peter; Keutner, Christoph; Berges, Ulf; Espeter, Philipp; Westphal, Carsten

    2017-03-01

    Key properties of steel like stability, weldability, or ability for absorbing deformation energy are defined by their grain structure. The knowledge about their micrometer and submicrometer structure is of particular interest for tailor-cut macroscopic steel properties. We report on photoemission electron microscopy studies which in principle yield a higher magnification than comparable optical techniques. A flat surface without any topographic features was obtained by applying a non-etching preparation procedure. PEEM images showed very tiny phase islands embedded within a steel phase matrix. Furthermore, we developed an analysis procedure for PEEM images for dual-phase steels. As a result, it is possible to identify the individual work functions of different steel phases at the surface.

  11. Photoemission Electron Microscopy as a Tool for Studying Steel Grains

    Science.gov (United States)

    Roese, Peter; Keutner, Christoph; Berges, Ulf; Espeter, Philipp; Westphal, Carsten

    2017-01-01

    Key properties of steel like stability, weldability, or ability for absorbing deformation energy are defined by their grain structure. The knowledge about their micrometer and submicrometer structure is of particular interest for tailor-cut macroscopic steel properties. We report on photoemission electron microscopy studies which in principle yield a higher magnification than comparable optical techniques. A flat surface without any topographic features was obtained by applying a non-etching preparation procedure. PEEM images showed very tiny phase islands embedded within a steel phase matrix. Furthermore, we developed an analysis procedure for PEEM images for dual-phase steels. As a result, it is possible to identify the individual work functions of different steel phases at the surface.

  12. Interpersonal synchrony enhanced through 20 Hz phase-coupled dual brain stimulation.

    Science.gov (United States)

    Novembre, Giacomo; Knoblich, Günther; Dunne, Laura; Keller, Peter E

    2017-01-24

    Synchronous movement is a key component of social behaviour in several species including humans. Recent theories have suggested a link between interpersonal synchrony of brain oscillations and interpersonal movement synchrony. The present study investigated this link. Using transcranial alternating current stimulation (tACS) applied over the left motor cortex, we induced beta band (20 Hz) oscillations in pairs of individuals who both performed a finger-tapping task with the right hand. In-phase or anti-phase oscillations were delivered during a preparatory period prior to movement and while the tapping task was performed. In-phase 20 Hz stimulation enhanced interpersonal movement synchrony, compared to anti-phase or sham stimulation, particularly for the initial taps following the preparatory period. This was confirmed in an analysis comparing real vs. pseudo pair surrogate data. No enhancement was observed for stimulation frequencies of 2 Hz (matching the target movement frequency) or 10 Hz (alpha band). Thus, phase-coupling of beta band neural oscillations across two individuals' (resting) motor cortices supports the interpersonal alignment of sensorimotor processes that regulate rhythmic action initiation, thereby facilitating the establishment of synchronous movement. Phase-locked dual brain stimulation provides a promising method to study causal effects of interpersonal brain synchrony on social, sensorimotor and cognitive processes.

  13. Magnetic-field-induced microstructural features in a high carbon steel during diffusional phase transformation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoxue, E-mail: zhangxiaoxue1213@gmail.com [Key Laboratory for Anisotropy and Texture of Materials (MOE), Northeastern University, Shenyang 110004 (China); Laboratoire d' Etude des Microstructures et de Mecanique des Materiaux (LEM3), CNRS UMR 7239, Universite de Lorraine UL 57045 Metz (France); Laboratory of Excellence on Design of Alloy Metals for low-mAss Structures (DAMAS), Universite de Lorraine (France); Zhang, Yudong, E-mail: yudong.zhang@univ-metz.fr [Laboratoire d' Etude des Microstructures et de Mecanique des Materiaux (LEM3), CNRS UMR 7239, Universite de Lorraine UL 57045 Metz (France); Laboratory of Excellence on Design of Alloy Metals for low-mAss Structures (DAMAS), Universite de Lorraine (France); Gong, Minglong, E-mail: gml@mail.neuq.edu.cn [Key Laboratory for Anisotropy and Texture of Materials (MOE), Northeastern University, Shenyang 110004 (China); Esling, Claude, E-mail: claude.esling@univ-metz.fr [Laboratoire d' Etude des Microstructures et de Mecanique des Materiaux (LEM3), CNRS UMR 7239, Universite de Lorraine UL 57045 Metz (France); Laboratory of Excellence on Design of Alloy Metals for low-mAss Structures (DAMAS), Universite de Lorraine (France); Zhao, Xiang, E-mail: zhaox@mail.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials (MOE), Northeastern University, Shenyang 110004 (China); Zuo, Liang, E-mail: lzuo@mail.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials (MOE), Northeastern University, Shenyang 110004 (China)

    2012-12-15

    In this work, a high purity, high carbon steel was heat treated without and with a 12-T magnetic field. The microstructural features induced by magnetic field during its diffusion-controlled austenite decomposition were investigated by means of optical microscopy and SEM/EBSD. It is found that the magnetic field increases the amount of the abnormal structure, which is composed of proeutectoid cementite along the prior austenite boundaries and ferrite around it, because magnetic field increases the austenite grain size and promotes the transformation of carbon-depleted austenite to ferrite. No specific orientation relationship between abnormal ferrite and cementite has been found in the non-field- or the field-treated specimens. Magnetic field evidently promotes the spheroidization of pearlite, due to its effect of enhancing carbon diffusion through raising the transformation temperature and its effect of increasing the relative ferrite/cementite interface energy. As magnetic field favors the nucleation of the high magnetization phase-pearlitic ferrite, the occurrence of the P-P2 OR that corresponds to the situation that ferrite nucleates prior to cementite during pearlitic transformation is enhanced by the magnetic field. - Highlights: Black-Right-Pointing-Pointer The field-induced microstructural features in a high carbon steel during diffusional phase transformation has been investigated. Black-Right-Pointing-Pointer Magnetic field increases the amount of the abnormal structure and promotes the spheroidization of pearlite. Black-Right-Pointing-Pointer Magnetic field enhances the occurrence of the P-P2 OR.

  14. Evolution of secondary phases in Cr-V low-alloy steels during aging

    Science.gov (United States)

    Janovec, J.; Vyrostková, A.; Svoboda, M.; Kroupa, A.; Grabke, H. J.

    2004-03-01

    The influence of both bulk vanadium content and aging conditions on the evolution of secondary phases in Cr-V low-alloy steels was studied. Three 0.1C-0.9Cr-V steels with different vanadium contents (0, 0.258, and 0.512 wt pct) were aged for 100 to 5,000 hours at 773, 853, 953, and 993 K. In the investigation, a limited experimental program (transmission electron microscopy (TEM)) was combined with credible thermodynamic predictions (ThermoCalc). Going out from the good agreement between the predicted and experimental results, behavior of the iron-rich M7C3 carbide in time-temperature scale was characterized. The influence of bulk vanadium content was determined on appearance of the M3C carbide in equilibrium, temperature of the M7C3 carbide precipitation, metal compositions of M3C or M7C3 carbides, and vanadium portion in the metallic part of the MX phase.

  15. submitter Damage evolution in a stainless steel bar undergoing phase transformation under torsion at cryogenic temperatures

    CERN Document Server

    Ortwein, R; Skoczen, B

    2016-01-01

    Phase transformation driven by plastic strains is commonly observed in austenitic stainless steels. In the present paper, this phenomenon is addressed in connection with damage evolution. A three-dimensional constitutive model has been derived, and scalar variables for damage and the volume fraction of the transformed phase were used. The model was solved using Abaqus UMAT user defined procedure, as well as by means of simplified one-dimensional approach for a twisted circular bar. Large experimental campaign of tests was performed, including martensite content measurements within the cross-section and on the surface of the bar during monotonic and cyclic loading. Based on the residual angle of twist, damage variable was calculated. The global response of torque versus the angle of twist was measured as well. Comparison between the experimental results and the results obtained from the simplified one-dimensional approach and from the full three-dimensional approach are presented. It turns out that one-dimensi...

  16. Valorization of BOF Steel Slag by Reduction and Phase Modification: Metal Recovery and Slag Valorization

    Science.gov (United States)

    Liu, Chunwei; Huang, Shuigen; Wollants, Patrick; Blanpain, Bart; Guo, Muxing

    2017-03-01

    Basic oxygen furnace (BOF) steel slag is a main byproduct in steelmaking, and its valorization is therefore of considerable interest, from a metal-recovery perspective and from a residue-utilization perspective. In the present study, the carbothermic reduction of BOF slag was investigated systematically. The reductions of Fe- and P-containing phases (i.e., oxide and compounds) are discussed. Effects of Al2O3 and SiO2 additions on the solidification microstructure and mineralogy associated with the reduction processes were also investigated. The formation and growth of the extracted metallic phase are discussed, and the mineralogy of the residue slag is determined. We conclude that by controlling the additions under a rapid cooling condition, it is possible to extract metallic iron as high-grade metal and simultaneously to utilize the remaining slag for construction applications.

  17. Optimized Carrier Based Multilevel Generated Modified Dual Three-Phase Open-Winding Inverter for Medium Power Applications

    DEFF Research Database (Denmark)

    Padmanaban, Sanjeevi Kumar; Blaabjerg, Frede; Wheeler, Patrick

    2016-01-01

    This paper presents a novel carrier based multilevel modulation for modified dual three-phase open-winding inverter applicable for low-voltage/high-current applications. A standard three-phase voltage source inverter (VSI) is connected across the open-winding of both ends of the motor. Each VSI i...

  18. Demonstration of dual-band infrared thermal imaging for bridge inspection. Phase II, final report

    Energy Technology Data Exchange (ETDEWEB)

    Durbin, P.F.; Del Grande, N.K.; Schaich, P.C.

    1996-03-01

    Developing and implementing methods of effective bridge rehabilitation is a major issue for the Federal Highway Administration (FHWA). The nation spends $5 billion annually to replace, rehabilitate or construct new bridges. According to the National Bridge Inventory, over 100,000 U.S. bridges are structurally deficient. About 40,000 of these bridges have advanced deck deterioration. The most common causes of serious deck deterioration is delamination. Delaminations result when steel reinforcements within the bridge deck corrode, creating gaps that separate the concrete into layers. A reliable inspection technology, capable of identifying delaminations, would represent a power new tool in bridge maintenance. To date, most bridge inspections rely on human interpretation of surface visual features of chain dragging. These methods are slow, disruptive, unreliable and raise serious safety concerns. Infrared thermal imaging detects subsurface delaminations and surface clutter, which is introduced by foreign material on the roadway. Typically, foreign material which is not always evident on a video tape image, produces a unique IR reflectance background unlike the thermal response of a subsurface delamination. Lawrence Livermore National Laboratory (LLNL) uses dual-band infrared (DBIR) thermal imaging to identify and remove nonthermal IR reflectance backgrounds from foreign material on the roadway. DBIR methods improve the performance of IR thermal imaging by a factor of ten, compared to single-band infrared (SBIR) methods. DBIR thermal imaging allows precise temperature measurement to reliably locate bridge deck delaminations and remove wavelength-dependent emissivity variations due to foreign material on the roadway.

  19. The performance of coherent receiver controlled by the phase lock loop in dual rate free-space laser communication

    Science.gov (United States)

    Ma, Xiaoping; Sun, Jianfeng; Hou, Peipei; Lu, Wei; Xu, Qian; Liu, Liren

    2015-09-01

    The technique of differential phase shift keying(DPSK) modulation is applied into demodulating phase information in the coherent optical receiver. The dual rate free-space receiving structure on the base of Mach-Zehnder delay interferometer with the lens is used suitably for differential delay which is equal to the one bit corresponding to a certain data rate. Delay distance at the interference receiver is varied with transmission rata from satellite to ground. Differential information is obtained by the subtraction of the two successive wave-front phases when made to interfere. The phase demodulation is extremely sensitive to phase fluctuation. Because of the incident light through atmospheric turbulence, the wave-front of optical signal became jittered in the temporal and spatial domain rapidly. In the paper, the dual rate free-space laser communication receiver for phase lock to stable signal light phase is proposed, increasing the homodyne efficiency and decreasing the bit error rate.

  20. 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.

  1. Single Walled Carbon Nanotubes Exhibit Dual-Phase Regulation to Exposed Arabidopsis Mesophyll Cells

    Science.gov (United States)

    Yuan, Hengguang; Hu, Shanglian; Huang, Peng; Song, Hua; Wang, Kan; Ruan, Jing; He, Rong; Cui, Daxiang

    2011-12-01

    Herein we are the first to report that single-walled carbon nanotubes (SWCNTs) exhibit dual-phase regulation to Arabidopsis mesophyll cells exposed to different concentration of SWCNTs. The mesophyll protoplasts were prepared by enzyme digestion, and incubated with 15, 25, 50, 100 μg/ml SWCNTs for 48 h, and then were observed by optical microscopy and transmission electron microscopy, the reactive oxygen species (ROS) generation was measured. Partial protoplasts were stained with propidium iodide and 4'-6- diamidino-2-phenylindole, partial protoplasts were incubated with fluorescein isothiocyanate-labeled SWCNTs, and observed by fluorescence microscopy. Results showed that SWCNTs could traverse both the plant cell wall and cell membrane, with less than or equal to 50 μg/ml in the culture medium, SWCNTs stimulated plant cells to grow out trichome clusters on their surface, with more than 50 μg/ml SWCNTs in the culture medium, SWCNTs exhibited obvious toxic effects to the protoplasts such as increasing generation of ROS, inducing changes of protoplast morphology, changing green leaves into yellow, and inducing protoplast cells' necrosis and apoptosis. In conclusion, single walled carbon nanotubes can get through Arabidopsis mesophyll cell wall and membrane, and exhibit dose-dependent dual-phase regulation to Arabidopsis mesophyll protoplasts such as low dose stimulating cell growth, and high dose inducing cells' ROS generation, necrosis or apoptosis.

  2. Single Walled Carbon Nanotubes Exhibit Dual-Phase Regulation to Exposed Arabidopsis Mesophyll Cells

    Directory of Open Access Journals (Sweden)

    Huang Peng

    2011-01-01

    Full Text Available Abstract Herein we are the first to report that single-walled carbon nanotubes (SWCNTs exhibit dual-phase regulation to Arabidopsis mesophyll cells exposed to different concentration of SWCNTs. The mesophyll protoplasts were prepared by enzyme digestion, and incubated with 15, 25, 50, 100 μg/ml SWCNTs for 48 h, and then were observed by optical microscopy and transmission electron microscopy, the reactive oxygen species (ROS generation was measured. Partial protoplasts were stained with propidium iodide and 4'-6- diamidino-2-phenylindole, partial protoplasts were incubated with fluorescein isothiocyanate-labeled SWCNTs, and observed by fluorescence microscopy. Results showed that SWCNTs could traverse both the plant cell wall and cell membrane, with less than or equal to 50 μg/ml in the culture medium, SWCNTs stimulated plant cells to grow out trichome clusters on their surface, with more than 50 μg/ml SWCNTs in the culture medium, SWCNTs exhibited obvious toxic effects to the protoplasts such as increasing generation of ROS, inducing changes of protoplast morphology, changing green leaves into yellow, and inducing protoplast cells' necrosis and apoptosis. In conclusion, single walled carbon nanotubes can get through Arabidopsis mesophyll cell wall and membrane, and exhibit dose-dependent dual-phase regulation to Arabidopsis mesophyll protoplasts such as low dose stimulating cell growth, and high dose inducing cells' ROS generation, necrosis or apoptosis.

  3. On Dual Phase-Space Relativity, the Machian Principle and Modified Newtonian Dynamics

    Directory of Open Access Journals (Sweden)

    Castro C.

    2005-04-01

    Full Text Available We investigate the consequences of the Mach’s principle of inertia within the context of the Dual Phase Space Relativity which is compatible with the Eddington-Dirac large numbers coincidences and may provide with a physical reason behind the observed anomalous Pioneer acceleration and a solution to the riddle of the cosmological constant problem. The cosmological implications of Non-Archimedean Geometry by assigning an upper impossible scale in Nature and the cosmological variations of the fundamental constants are also discussed. We study the corrections to Newtonian dynamics resulting from the Dual Phase Space Relativity by analyzing the behavior of a test particle in a modified Schwarzschild geometry (due to the the effects of the maximal acceleration that leads in the weak-field approximation to essential modifications of the Newtonian dynamics and to violations of the equivalence principle. Finally we follow another avenue and find modified Newtonian dynamics induced by the Yang’s Noncommutative Spacetime algebra involving a lower and upper scale in Nature.

  4. Development of an i-line attenuated phase shift process for dual inlay interconnect lithography

    Science.gov (United States)

    Sturtevant, John L.; Ho, Benjamin C. P.; Geiszler, Vincent C.; Herrick, Matthew T.; King, Charles F.; Carter, Russell L.; Roman, Bernard J.; Litt, Lloyd C.; Smith, Brad; Strozewski, Kirk J.

    2000-06-01

    The transition from aluminum/oxide to copper/low-k dielectric interconnect technology involves a variety of fundamental changes in the back-end manufacturing process. The most attractive patterning strategy involves the use of a so-called dual inlay approach, which offers lower fabrication costs by the elimination of one inter-level dielectric (ILD) deposition and polish sequence per metal layer. In this paper, the lithographic challenges for dual inlay, including thin-film interference effect, resist bulk effect, and optical proximity effects are reviewed. The use of attenuated phase shift (aPSM) reticles for patterning vias and trenches was investigated, and shown to provide adequate process margin by optimizing the photoresist and exposure tool parameters. Our results indicate that using appropriately sized attenuated phase shift technique increases the photospeed considerably and simultaneously improves the common process window with sufficient sidelobe suppression margin. The cost of ownership tradeoffs between an attenuated PSM I-Line process and a DUV binary process are discussed.

  5. First faint dual-field phase-referenced observations on the Keck interferometer

    CERN Document Server

    Woillez, Julien; Akeson, Rachel; Colavita, Mark; Eisner, Josh; Millan-Gabet, Rafael; Monnier, John; Pott, Jorg-Uwe; Ragland, Sam; Appleby, Eric; Cooper, Andrew; Felizardo, Claude; Herstein, Jennifer; Martin, Olivier; Medeiros, Drew; Morrison, Douglas; Panteleeva, Tatyana; Smith, Brett; Summers, Kellee; Tsubota, Kevin; Tyau, Colette; Wetherell, Ed

    2012-01-01

    Ground-based long baseline interferometers have long been limited in sensitivity by the short integration periods imposed by atmospheric turbulence. The first observation fainter than this limit was performed on January 22, 2011 when the Keck Interferometer observed a K=11.5 target, about one magnitude fainter than its K=10.3 limit. This observation was made possible by the Dual Field Phase Referencing instrument of the ASTRA project: simultaneously measuring the real-time effects of the atmosphere on a nearby bright guide star, and correcting for it on the faint target, integration time longer than the turbulence time scale are made possible. As a prelude to this demonstration, we first present the implementation of Dual Field Phase Referencing on the interferometer. We then detail its on-sky performance focusing on the accuracy of the turbulence correction, and on the resulting fringe contrast stability. We conclude with a presentation of early results obtained with Laser Guide Star AO and the interferomete...

  6. Dual-channel in-line digital holographic double random phase encryption.

    Science.gov (United States)

    Das, Bhargab; Yelleswarapu, Chandra S; Rao, D V G L N

    2012-10-01

    We present a robust encryption method for the encoding of 2D/3D objects using digital holography and virtual optics. Using our recently developed dual-plane in-line digital holography technique, two in-line digital holograms are recorded at two different planes and are encrypted using two different double random phase encryption configurations, independently. The process of using two mutually exclusive encryption channels makes the system more robust against attacks since both the channels should be decrypted accurately in order to get a recognizable reconstruction. Results show that the reconstructed object is unrecognizable even when the portion of the correct phase keys used during decryption is close to 75%. The system is verified against blind decryptions by evaluating the SNR and MSE. Validation of the proposed method and sensitivities of the associated parameters are quantitatively analyzed and illustrated.

  7. Modulation of auroral electrojet currents using dual HF beams with ELF phase offset

    Science.gov (United States)

    Golkowski, M.; Cohen, M.; Moore, R. C.

    2012-12-01

    The modulation of naturally occuring ionospheric currents with high power radio waves in the high frequency (HF, 3-10 MHz) band is a well known technique for generation of extremely low frequency (ELF, 3-3000 Hz) and very low frequency (VLF, 3-30 kHz) waves. We use the heating facility of the High Frequency Active Auroral Research Program (HAARP) to investigate the effect of using dual HF beams with an ELF/VLF phase offset between the modulation waveforms. Experiments with offset HF beams confirm the model of independent ELF/VLF sources. Experiments with co-located HF beams exhibit interaction between the first and second harmonics of the modulated tones when square and sine wave modulation waveforms are employed. Using ELF/VLF phase offsets for co-loacted beams is also shown to be a potential diagnostic for the D-region ionospheric profile.

  8. Optical image hiding based on dual-channel simultaneous phase-shifting interferometry and compressive sensing

    Science.gov (United States)

    Li, Jiaosheng; Zhong, Liyun; Zhang, Qinnan; Zhou, Yunfei; Xiong, Jiaxiang; Tian, Jindong; Lu, Xiaoxu

    2017-01-01

    We propose an optical image hiding method based on dual-channel simultaneous phase-shifting interferometry (DCSPSI) and compressive sensing (CS) in all-optical domain. In the DCSPSI architecture, a secret image is firstly embedded in the host image without destroying the original host's form, and a pair of interferograms with the phase shifts of π/2 is simultaneously generated by the polarization components and captured by two CCDs. Then, the holograms are further compressed sampling to the less data by CS. The proposed strategy will provide a useful solution for the real-time optical image security transmission and largely reducing data volume of interferogram. The experimental result demonstrates the validity and feasibility of the proposed method.

  9. Hybrid Modulation of Bidirectional Three-Phase Dual-Active-Bridge DC Converters for Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Yen-Ching Wang

    2016-06-01

    Full Text Available Bidirectional power converters for electric vehicles (EVs have received much attention recently, due to either grid-supporting requirements or emergent power supplies. This paper proposes a hybrid modulation of the three-phase dual-active bridge (3ΦDAB converter for EV charging systems. The designed hybrid modulation allows the converter to switch its modulation between phase-shifted and trapezoidal modes to increase the conversion efficiency, even under light-load conditions. The mode transition is realized in a real-time manner according to the charging or discharging current. The operation principle of the converter is analyzed in different modes and thus design considerations of the modulation are derived. A lab-scaled prototype circuit with a 48V/20Ah LiFePO4 battery is established to validate the feasibility and effectiveness.

  10. Transient heterogeneous enhancement on dual-phase helical CT of liver

    Energy Technology Data Exchange (ETDEWEB)

    Ishibashi, Tadashi; Hama, Hikaru; Oikawa, Hideki; Yamada, Takayuki; Abe, Hiroyuki; Saitoh, Haruo; Sakamoto, Kiyohiko [Tohoku Univ., Sendai (Japan). School of Medicine; Satoh, Akihiro

    1996-08-01

    Transient heterogeneous enhancement was seen on the arterial phase of dual-phase helical CT of the liver. The shape of the enhancement was appeared wedged or patchy. These phenomena without liver tumor were observed in 23 (2.3%) of 1012 patients with suspected hepatobiliary disease. Plain CT showed no attenuation difference in the liver. Twenty-two of these 23 cases were diagnosed as scarred liver, A-P shunt caused by liver biopsy, acute cholecystitis, liver abscess, liver cirrhosis, or advanced pancreas head cancer. The diagnosis of one case was uncertain. These phenomena were thought to be caused by a regional direct increase in hepatic arterial flow due to arterial-portal (A-P) shunt, or hypervascular tumor; or a compensatory increase in hepatic arterial flow as a result of decreased portal venous flow caused by tumor invasion or severe liver cirrhosis. (author)

  11. ROLE OF 99Tcm-SESTAMIBI DUAL-PHASE PARATHYROID SCINTIGRAPHY IN PREOPERATIVE LOCALIZATION IN PATIENTS WITH PRIMARY HYPERPARATHYROIDISM

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective To evaluate the application of 99Tcm-sestamibi dual-phase parathyroid scintigraphy in the preoperative localization in patients with primary hyperparathyroidism and to compare the diagnostic efficacy of various imaging modalities. Methods Ninety-two consecutive patients, diagnosed as hyperparathyroidism and presented with hypercalcaemia as the predominant symptom, were included. All the patients underwent dual-phase parathyroid scintigraphy using 99Tcm-sestamibi and parathyroid ultrasound scan. Among them, 48 patients underwent parathyroid computed tomography (CT). All patients were referred for parathyroidectomy. Results 99Tcm-sestamibi dual-phase parathyroid scintigraphy revealed the diagnostic sensitivity of 76.5%, 80%, 75% and 33.3% for the subgroup of single adenomas, multiple adenomas, ectopic parathyroid and parathyroid hyperplasia respectively. The specificity was 100% for all leisons. 99Tcm-sestamibi dual-phase parathyroid scintigraphy was proved to be superior to the other imaging modalities (ultrasound and CT) in terms of the preoperative diagnostic accuracy. The lesion weight was found to be an underlying factor leading to the false negative result. Conclusion 99Tcm-sestamibi dual-phase parathyroid scintigraphy was found to have higher diagnostic accuracy in comparison with other imaging modalities and is recommended preoperatively in order to reduce the sugery time and unnecessary neck exploration.

  12. An EFTEM study on Z-phase nucleation in martensitic chromium steels

    Energy Technology Data Exchange (ETDEWEB)

    Golpayegani, A.; Andren, H.O. [Chalmers Univ. of Technology, Gothenburg (Sweden). Microscopy and Microanalysis, Dept. of Applied Physics

    2006-07-01

    9-12% Cr martensitic steels that are used in crucial parts of steam power plants have been found liable to the precipitation of Z-phase after long time at service temperature. This complex nitride consumes vanadium nitrides and leaves the matrix with a relatively big vanadium poor region causing the creep strength of material to fall drastically after several thousand hours. it is of great importance to monitor the initial stages of precipitation of this phase to understand the factors promoting it and to get ideas about ways to suppress or eliminate it. In this work, Z-phase has been characterized using energy-filtered TEM. lt has been found that VN provides the most suitable nucleation site for Z-phase since its lattice has the minimum misfit for starting the nucleation and it also provides vanadium for the growth. it has also been observed that the presence of niobium carbide close to the nucleation site is crucial for the nucleation and growth of this phase. (orig.)

  13. Precipitation of Phase Using General Diffusion Equation with Comparison to Vitek Diffusion Model in Dissimilar Stainless Steels

    Directory of Open Access Journals (Sweden)

    Chih-Chun Hsieh

    2012-01-01

    Full Text Available This study performs a precipitation examination of the phase using the general diffusion equation with comparison to the Vitek model in dissimilar stainless steels during multipass welding. Experimental results demonstrate that the diffusivities (, , and of Cr, Ni, and Si are higher in -ferrite than (, , and in the phase, and that they facilitate the precipitation of the σ phase in the third pass fusion zone. The Vitek diffusion equation can be modified as follows: .

  14. Experimental Determination of the Primary Solidification Phase dependency on the solidification velocity for 17 different austenitic stainless steel compositions

    DEFF Research Database (Denmark)

    Laursen, Birthe Nørgaard; Olsen, Flemming Ove; Yardy, John;

    1997-01-01

    to the austenite phase.Most stainless steels are weldable by conventional welding techniques. However, during laser weldng the solidification velocities can be very much higher than by conventional welding techniques. By increasing the solidification velocity to a critical value known as the transition velocity......, the primary solidification phase is found to change from ferrite to austenite.A novel laser remelting technique has been modified to enable the transition velocity for laser welded austenitic stainless steels to be deermined experimentally and on the basis of results from 17 different alloy compositions...... an equation for the calculation of the transition velocity from alloy composition is proposed....

  15. Fundamental Studies of Phase Transformations and Mechanical Properties in the Heat Affected Zone of 10 wt% Nickel Steel

    Science.gov (United States)

    Barrick, Erin J.

    United States naval applications require the use of steels with high strength and resistance to fracture at low temperatures to provide good ballistic properties. In recent years, 10 wt% Ni steel has been developed with strength and toughness values exceeding those of steels currently used, and is now being considered as a candidate material to replace existing high-strength, low alloy steels. This steel has excellent toughness from the mechanically induced transformation of interlath austenite films to martensite. These austenite films are formed via a carefully developed quenching, lamellarizing, and tempering heat treatment. However, before 10 wt% Ni steel can be implemented for full-scale applications, the effects of the rapid heating and cooling rates associated with welding thermal cycles on phase transformations and mechanical properties must be understood. In this research, a fundamental understanding of phase transformations and mechanical properties in the heat-affected zone of fusion welds in 10 wt% Ni steel was developed through heating and cooling rate dilatometry experiments, gas tungsten arc welding, and simulation of gas metal arc welding. First, an investigation into the effects of heating and cooling rate on the phase transformations in 10 wt% Ni steel was performed. The Ac1 and Ac3 temperatures during heating were determined as a function of heating rate, and sluggish transformation during fast heating rates manifested itself as a high Ac3 temperature of 1050°C as opposed to a temperature of 850°C at slow heating rates. A continuous cooling transformation diagram produced for 10 wt% Ni steel reveals that martensite will form over a very wide range of cooling rates, which reflects a very high hardenability of this alloy. This is significant because the range of cooling rates for which the diagram was constructed over easily covers the range associated with fusion welding, so there would not be the need for precise control over the weld

  16. Microstructure, crystallography of phase transformations and multiple precipitations in PH 15-7Mo stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hongwei [The Australia Centre Microscopy and Microanalysis, The University of Sydney, NSW, 2006 (Australia); Liu, Jiangwen, E-mail: mejwliu@scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510640 (China); Luo, Chengping [School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510640 (China); Liu, Zhijian [Guangdong Research Institute of Iron and Steel, Guangzhou, 510640 (China)

    2016-07-05

    The microstructure and crystallographic features of a semi-austenitic precipitation hardening steel PH 15-7Mo during solution treatment, roddrawing and aging were investigated by means of optical microscope, X-ray diffraction analyzer and transmission electron microscope. It was found that the microstructure of the steel was consist of dominant austenite, small amount of martensite and 10–15 vol.% δ-ferrite after solution treatment at 1050 °C followed by cooling in water at room temperature. The austenite transformed into lath martensite during tensile roddrawing about 60% deforming companied with some coherent fine β-NiAl particles precipitated within martensite. With higher aging temperature and longer holding time, tiny carbide M{sub 23}C{sub 6} particles precipitated from martensite, which kept the cubic–cubic orientation relationship (OR) with austenite and G-T OR with martensite which is different with all the reported orientations. The OR between tiny carbide M{sub 23}C{sub 6} particles G-T OR with martensite was discussed in terms of crystallography of phase transformations. - Highlights: • Microstructure changes of austenitic steel PH15-7Mo were due to alloying elements, service condition and carbide M{sub 23}C{sub 6}. • Lath-shape martensitic laths keep pseudo {112} twinning relationship. • β-NiAl particles hold a typical cubic-to-cubic orientation relationship with martensite. • M{sub 23}C{sub 6} carbide kept a cubic–cubic orientation relationship (OR) with austenite and an unusual G-T OR with martensite. • Multiple orientation relationship between M{sub 23}C{sub 6} and austenite is correlative with their structural similarity.

  17. Thermophysical Properties of a Chromium Nickel Molybdenum Steel in the Solid and Liquid Phases

    Science.gov (United States)

    Wilthan, B.; Reschab, H.; Tanzer, R.; Schützenhöfer, W.; Pottlacher, Gernot

    2008-02-01

    Numerical simulation of vacuum arc re-melting, pressurized or protective electro-slag re-melting, and ingot casting have become quite important in the metal industry. However, a major drawback of these simulation techniques is the lack of accurate thermophysical properties for temperatures above 1,500 K. Heat capacity, heat of fusion, density, and thermal conductivity are important input parameters for the heat transfer equation. Since, direct measurements of thermal conductivity of alloys in the liquid state are almost impossible, its estimation from electrical conductivity using the Wiedemann Franz law is very useful. The afore-mentioned thermophysical properties of several steels are investigated within the context of an ongoing project. Here, we present a full set of thermophysical data for the chromium nickel molybdenum steel meeting the standard DIN 1.4435 (X2CrNiMo18-14-3); these values will be used by our partner to simulate various re-melting and solidification processes. Wire-shaped samples of the steel are resistively volume-heated, as part of a fast capacitor discharge circuit. Time-resolved measurements with sub-μs resolution of current through the specimen are performed with a Pearson probe. The voltage drop across the specimen is measured with knife-edge contacts and ohmic voltage dividers, the temperature of the sample with a pyrometer, and the volumetric expansion of the wire with a fast acting CCD camera. These measurements enable the heat of fusion, the heat capacity, and the electrical resistivity to be determined as a function of temperature in the solid and liquid phases. The thermal conductivity and thermal diffusivity are estimated via the Wiedemann Franz law.

  18. Phase evolution and mechanical behavior of 0.36 wt% C high strength TRIP-assisted steel

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Swarup Kumar; Chattopadhyay, Partha Protim [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India)

    2012-12-15

    Phase evolution in a 0.36 wt% C steel has been studied by thermodynamic calculation and dilatometric analysis with an aim to achieve high strength TRIP-assisted steel with bainitic microstructure. The equilibrium phase fraction calculated as the function of temperature indicated the formation of {delta}-ferrite ({approx}98%) at 1417 C. In contrast, similar calculation under para-equilibrium condition exhibited transformation of {delta}-ferrite to austenite at the temperature below 1300 C. During further cooling two-phase ({alpha}+{gamma}) microstructure has been found to be stable at the intercritical temperature range. The experimentally determined CCT diagram has revealed that adequate hardenability is achievable in the steel under continuous cooling condition at cooling rate >5 C s{sup -1}. In view of the aforesaid results, the steel has been hot rolled and subjected to different process schedule conducive to the evolution of bainitic microstructure. The hot rolled steel has exhibited reasonably good tensile properties. However, cold deformation of the hot rolled sample followed by intercritical annealing and subsequent isothermal bainitic transformation has resulted in high strength (>1000 MPa) with attractive elongation due to the favorable work hardening condition during plastic deformation offered by the multiphase microstructure. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. In-Situ Phase Mapping and Direct Observations of Phase Transformations During Arc Welding of 1045 Steel

    Energy Technology Data Exchange (ETDEWEB)

    Elmer, J; Palmer, T

    2005-09-13

    In-situ Spatially Resolved X-Ray Diffraction (SRXRD) experiments were performed during gas tungsten arc (GTA) welding of AISI 1045 C-Mn steel. Ferrite ({alpha}) and austenite ({gamma}) phases were identified and quantified in the weld heat-affected zone (HAZ) from the real time x-ray diffraction data. The results were compiled along with weld temperatures calculated using a coupled thermal fluids weld model to create a phase map of the HAZ. This map shows the {alpha} {yields} {gamma} transformation taking place during weld heating and the reverse {gamma} {yields} {alpha} transformation taking place during weld cooling. Superheating is required to complete the {alpha} {yields} {gamma} phase transformation, and the amount of superheat above the A3 temperature was shown to vary with distance from the centerline of the weld. Superheat values as high as 250 C above the A3 temperature were observed at heating rates of 80 C/s. The SRXRD experiments also revealed details about the {gamma} phase not observable by conventional techniques, showing that {gamma} is present with two distinct lattice parameters as a result of inhomogeneous distribution of carbon and manganese in the starting pearlitic/ferritic microstructure. During cooling, the reverse {gamma} {yields} {alpha} phase transformation was shown to depend on the HAZ location. In the fine grained region of the HAZ, at distances greater than 2 mm from the fusion line, the {gamma} {yields} {alpha} transformation begins near the A3 temperature and ends near the A1 temperature. In this region of the HAZ where the cooling rates are below 40 C/s, the transformation occurs by nucleation and growth of pearlite. For HAZ locations closer to the fusion line, undercoolings of 200 C or more below the A1 temperature are required to complete the {gamma} {yields} {alpha} transformation. In this region of the HAZ, grain growth coupled with cooling rates in excess of 50 C/s causes the transformation to occur by a bainitic mechanism.

  20. Phase formation in selected surface-roughened plasma-nitrided 304 austenite stainless steel

    Directory of Open Access Journals (Sweden)

    Gajendra Prasad Singh et al

    2008-01-01

    Full Text Available Direct current (DC glow discharge plasma nitriding was carried out on three selected surface-roughened AISI 304 stainless steel samples at 833 K under 4 mbar pressures for 24 h in the presence of N2:H2 gas mixtures of 50 : 50 ratios. After plasma nitriding, the phase formation, case depth, surface roughness, and microhardness of a plasma-nitrided layer were evaluated by glancing angle x-ray diffractogram, optical microscope, stylus profilometer, and Vickers microhardness tester techniques. The case depth, surface hardness, and phase formation variations were observed with a variation in initial surface roughness. The diffraction patterns of the plasma-nitrided samples showed the modified intensities of the α and γ phases along with those of the CrN, Fe4N, and Fe3N phases. Hardness and case depth variations were observed with a variation in surface roughness. A maximum hardness of 1058 Hv and a case depth of 95 μm were achieved in least surface-roughened samples.

  1. Precipitation of σ phase in superaustenitic stainless steel UHB 904L

    Directory of Open Access Journals (Sweden)

    F. Tehovnik

    2017-01-01

    Full Text Available Superaustenitic stainless steel UHB 904L with high Mo concentrations is widely used in applications that require high toughness and corrosion resistance. Given certain thermal histories, UHB 904L may be susceptible to the formation of potentially detrimental intermetallic phases, such as the σ (sigma phase. The formation of the σ phase is promoted by high concentrations of Cr and Mo, while elements such as carbon, nickel and nitrogen retard its formation. Samples of UHB 904L were isothermally annealed within the temperature range between 850 – 1 000 °C, for 8 h each, followed by water quenching. Microstructural analyses using light and electron microscopy showed that the σ phase forms at temperatures up to 1 000 °C. The tensile specimens were solution treated at 1 000 °C, 1 060 °C, 1 100 °C and 1 140 °C for 0,5 h, followed by water quenching. The tensile tests were performed at room temperature.

  2. Packed column supercritical fluid chromatography using stainless steel particles and water as a stationary phase.

    Science.gov (United States)

    Murakami, Jillian N; Thurbide, Kevin B

    2015-09-15

    Stainless steel (SS) particles were demonstrated as a novel useful support for a water stationary phase in packed column supercritical fluid chromatography using a CO2 mobile phase. Separations employed flame ionization detection, and the system was operated over a range of temperatures and pressures. Retention times reproduced well with RSD values of 2.6% or less. Compared to analogous separations employing a water stationary phase coated onto a SS capillary column, the packed column method provided separations that were about 10× faster, with nearly 8-fold larger analyte retention factors, while maintaining good peak shape and comparable column efficiency. Under normal operating conditions, the packed column contains about 131 ± 4 μL/m of water phase (around a 5% m/m coating), which is over 25× greater than the capillary column and also affords it a 20-fold larger sample capacity. Several applications of the packed column system are examined, and the results indicate that it is a useful alternative to the capillary column mode, particularly where analyte loads or sample matrix interference is a concern. Given its high sample capacity, this packed column method may also be useful to explore on a more preparative scale in the future.

  3. Reduction of Anisotropy in Cold-Rolled Duplex Stainless Steel Sheets by Using Sigma Phase Transformation

    Science.gov (United States)

    Fargas, G.; Akdut, N.; Anglada, M.; Mateo, A.

    2011-11-01

    The mechanical properties of rolled duplex stainless steel (DSS) products manufactured by the current industrial process exhibit a strong anisotropy. This fact is evidently due to the two-phase nature of DSSs. During industrial rolling, not only the morphology of the microstructure changes from coarse-grained isotropic in the cast slab to fine-grained anisotropic in the coil, with both phases elongated in the rolling direction (RD), but also clear and intense crystallographic rolling textures develop, especially in the ferritic phase. The objective of the present work was to modify the industrial processing route and parameters in such a way that the strong anisotropy of DSS coils and sheets is decreased and the amount of potential applications made from DSSs by deep drawing or roll forming operations is increased. To achieve this goal, after the industrial cold rolling, a heat treatment is proposed with the aim of modifying the morphology and crystallographic texture of the ferritic grains by the assistance of an enforced transformation to sigma phase. The final product obtained by this modified route showed a microstructure with grains of austenite and ferrite randomly distributed and a significant decrease of the texture intensities due to the retransformation of sigma into ferrite. As a result, DSS EN 1.4462 displayed an almost isotropic mechanical behavior and an improved aptitude to deep drawing operations.

  4. Phase formation in selected surface-roughened plasma-nitrided 304 austenite stainless steel.

    Science.gov (United States)

    Singh, Gajendra Prasad; Joseph, Alphonsa; Raole, Prakash Manohar; Barhai, Prema Kanta; Mukherjee, Subroto

    2008-04-01

    Direct current (DC) glow discharge plasma nitriding was carried out on three selected surface-roughened AISI 304 stainless steel samples at 833 K under 4 mbar pressures for 24 h in the presence of N2:H2 gas mixtures of 50 : 50 ratios. After plasma nitriding, the phase formation, case depth, surface roughness, and microhardness of a plasma-nitrided layer were evaluated by glancing angle x-ray diffractogram, optical microscope, stylus profilometer, and Vickers microhardness tester techniques. The case depth, surface hardness, and phase formation variations were observed with a variation in initial surface roughness. The diffraction patterns of the plasma-nitrided samples showed the modified intensities of the α and γ phases along with those of the CrN, Fe4N, and Fe3N phases. Hardness and case depth variations were observed with a variation in surface roughness. A maximum hardness of 1058 Hv and a case depth of 95 μm were achieved in least surface-roughened samples.

  5. Frequency domain phase noise analysis of dual injection-locked optoelectronic oscillators.

    Science.gov (United States)

    Jahanbakht, Sajad

    2016-10-01

    Dual injection-locked optoelectronic oscillators (DIL-OEOs) have been introduced as a means to achieve very low-noise microwave oscillations while avoiding the large spurious peaks that occur in the phase noise of the conventional single-loop OEOs. In these systems, two OEOs are inter-injection locked to each other. The OEO with the longer optical fiber delay line is called the master OEO, and the other is called the slave OEO. Here, a frequency domain approach for simulating the phase noise spectrum of each of the OEOs in a DIL-OEO system and based on the conversion matrix approach is presented. The validity of the new approach is verified by comparing its results with previously published data in the literature. In the new approach, first, in each of the master or slave OEOs, the power spectral densities (PSDs) of two white and 1/f noise sources are optimized such that the resulting simulated phase noise of any of the master or slave OEOs in the free-running state matches the measured phase noise of that OEO. After that, the proposed approach is able to simulate the phase noise PSD of both OEOs at the injection-locked state. Because of the short run-time requirements, especially compared to previously proposed time domain approaches, the new approach is suitable for optimizing the power injection ratios (PIRs), and potentially other circuit parameters, in order to achieve good performance regarding the phase noise in each of the OEOs. Through various numerical simulations, the optimum PIRs for achieving good phase noise performance are presented and discussed; they are in agreement with the previously published results. This further verifies the applicability of the new approach. Moreover, some other interesting results regarding the spur levels are also presented.

  6. The role of dual-phase helical CT in assessing resectability of carcinoma of the gallbladder

    Energy Technology Data Exchange (ETDEWEB)

    Kumaran, Vinay; Pande, Girish Kumar; Sahni, Peush; Chattopadhyay, Tushar Kanti [Department of Gastrointestinal Surgery, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110 029 (India); Gulati, Manpreet Singh; Paul, Shashi Bala [Department of Radiodiagnosis, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110 029 (India)

    2002-08-01

    Our objective was to assess the ability of dual-phase helical CT (DHCT) to predict resectability of carcinoma of gallbladder (CaGB). Thirty-two consecutive patients suspected of having CaGB on clinical examination and sonography presented to our centre over 10-month period. All these 32 patients underwent DHCT. Fifteen patients were considered inoperable and 2 had xanthogranulomatous cholecystitis. The remaining 15 patients (10 women, 5 men; age range 33-72 years) underwent surgery and had histopathological confirmation of CaGB and were included in the study based on the following criteria: presence of mass in gallbladder fossa on sonography and DHCT, and confirmation at surgery and histopathological examination. Axial reconstructions of 2 mm were obtained (collimation 3 mm, table speed 4.5 mm/s) for arterial (scan delay 20 s) and venous (scan delay 60 s) phases on a helical scanner. The criteria used for unresectability were: distant metastasis (liver, peritoneum, lymph nodes), extensive local contiguous organ spread, involvement of secondary biliary confluence of both lobes of liver, tumoral invasion of main portal vein, or proper hepatic artery or simultaneous invasion of one side hepatic artery and the other side portal vein. The CT findings related to unresectability were correlated with surgical findings. On the basis of CT findings, 10 patients were unresectable and 5 were resectable. Of the 10 patients considered unresectable, 9 had tumours that were unresectable at surgery (sensitivity 100%, positive predictive value 90%). Five patients had more than one reason and 4 had one reason alone for being unresectable (lymph nodes, n=2; hepatic metastasis, n=1; and vascular invasion, n=1). All 5 patients considered resectable based on CT findings had resectable tumours at surgery (negative predictive value 100%). The overall accuracy of CT was 93.3%. Dual-phase helical CT comprehensively evaluates CaGB and may be a useful tool in preoperative staging of this

  7. Thermal Diffusivity and Thermal Conductivity of Five Different Steel Alloys in the Solid and Liquid Phases

    Science.gov (United States)

    Wilthan, B.; Schützenhöfer, W.; Pottlacher, G.

    2015-08-01

    The need for characterization of thermophysical properties of steel and nickel-based alloys was addressed in the FFG-Bridge Project 810999 in cooperation with a partner from industry, Böhler Edelstahl GmbH & Co KG. To optimize numerical simulations of production processes, such as remelting or plastic deformation, additional, and more accurate data were necessary for the alloys under investigation. With a fast ohmic pulse heating circuit system, the temperature-dependent specific electrical resistivity, density, and specific heat capacity for a set of five high alloyed steels were measured. Hence, using the Wiedemann-Franz law with a Lorenz number of , the thermal diffusivity and thermal conductivity could be calculated for the solid and liquid phases up to temperatures of 2500 K. This experimental approach is limited by the following requirements for the specimens: they have to be electrically conducting, the melting point has to be high enough for the implemented pyrometric temperature measurement, and one has to be able to draw wires of the material. The latter restriction is technologically challenging with some of the materials being very brittle. For all samples, electrical and temperature signals are recorded and a fast shadowgraph method is used to measure the volume expansion. For each material under investigation, a set of data including the chemical composition, the density at room temperature, solidus and liquidus temperatures, and the change of enthalpy, resistivity, density, thermal conductivity, and thermal diffusivity as a function of temperature is reported.

  8. EBSD ANALYSIS OF PHASE COMPOSITIONS OF TRIP STEEL ON VARIOUS STRAIN LEVELS

    Directory of Open Access Journals (Sweden)

    Ondřej Man

    2009-05-01

    Full Text Available Flat test bar made of TRIP steel was sequentially strained in tension. Eeach deformation step was made on a predefined strain level in which the phase composition was measured using EBSD; the analyses were made ex-situ exactly in the same area of 30x30µm. Retained austenite (RA was present in the form of elongated grains (plates and roughly equiaxial ones. The RA content was initially 14.5% and decreased with imposed strain down to approximately 5% in selected strain range from 0% to 10%. This is in agreement to some extent with outcomes of both in-situ and ex-situ experiments presented by other authors, the difference beeing supposed either in data clean up or in variation in micriostruct ure of particular steel. Kernel average misorientation method was confirmed as useful tool to discern bainite and grainy ferrite in lightly deformed specimen. Problem arose in distinguishing between martensite and deformed ferrite at higher deformation levels because of high dislocation density and/or lattice distortion in both components. The ferrite and retained austenite fraction were analysed with sufficient accuracy; martensite fraction was established with high degree of uncertainty.

  9. Correlation between contrast enhancement of portal vein and spleen size in dual-phase spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Seung Eon; Choi, Jong Cheol; Nam, Kyung Jin; Jung, Won Jung; Goo, Bong Sik; Park, Byung Ho; Lee, Young Ii; Chung, Duck Hwan [Donga Univ. College of Medicine, Pusan (Korea, Republic of)

    1996-10-01

    To evaluate using spiral CT the effect of spleen size on blood flow in the portal venous system and to know the usefulness of this evaluation. Fifty-one patients without evidence on spiral CT scan of abnormality thought to affect portal venous flow presented between December 1994 and June 1995. We measured spleen size and Hounsfield units of portal vein in dual-phase, and calculated the ratio of the unit in the portal phase to that in the arterial phase. Spleen size was measured, using the length of X-axis by that of Z-axis on spiral CT scan. We then measured the correlation between the two values. CT was performed with a Somatom Plus-S scanner(Siemens, Erlangen, Germany). A total dose of 120ml of non-ionic contrast material(Ultravist) was administered at a rate of 3 ml/sec. Arterial and portal phase were obtained after 30 seconds and 60 seconds from the begining of the contrast agent injection. The correlation between spleen size and contrast enhancement of the portal vein was relatively significant(Pearson's correlation coefficient(r)=0.41801). Spleen size significantly affects portal venous flow on spiral CT scan. The evaluation of spleen size and contrast enhancement of the portal vein could be useful in the differential diagnosis of diseases which affect portal venous flow.

  10. Influence of Chemical Composition on Phase Transformation Temperature and Thermal Expansion Coefficient of Hot Work Die Steel

    Institute of Scientific and Technical Information of China (English)

    XIE Hao-jie; WU Xiao-chun; MIN Yong-an

    2008-01-01

    On the basis of the uniform design method,six kinds of martensitie hot work die steels were designed.The phase transformation temperatures including Ac1,Ac3,and M,were measured by DIL805A quenching dilatometer.The influences of the main elements on phase transformation temperatures were analyzed by quadratic stepwise regression analysis,and three corresponding equations were obtained.These equations,in which the interactions of the elements were considered,showed more effectiveness than the traditional ones.In addition,the thermal expansion coefficients of these steels in annealed state and quenched state were also obtained during the tests.The influences of chemical composition and temperature on the thermal expansion coefficient were analyzed;the equations obtained Were verified by using several kinds of steels.The predicted values were in accordance with the results of the experiments.

  11. Martensite transformation induced by deformation and its phase electrochemical behavior for stainless steels AISI 304 and 316L

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The martensite transformation induced by tensile elongation and its effect on the behavior of phase electrochemistry of AISI 304 and 316L in 3.5% NaCl solution were studied. The results show that the content of ((-martensite in stainless steel 304 increases with the true strain. As ((-martensite content increased, free corrosion potential and pitting potential of stainless steel 304 in 3.5% NaCl solution appeared the change trend of a minimum. It was also found that pitting nucleated preferentially at the phase interfaces between martensite and austenite. There existed apparent difference between electrochemical properties of austenite and of martensite for stainless steel 304 and 316L in 3.5% NaCl solution.

  12. Study on absorption coefficients of dual-energy γ-rays in determining phase fractions of multiphase flows

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-biao; LI Dong-hui; WU Ying-xiang

    2005-01-01

    This paper discusses the principle and mathematical method to measure the phase fractions of multiphase flows by using a dual-energy gamma-ray system. The dual-energy gamma-ray device is composed of radioactive isotopes of 241Am and 137Cs with emission energies of 59.5 keV and 662 keV respectively. A rational method to calibrate the absorption coefficient was introduced in detail. The statistical error has been analyzed on the basis of the accurate absorption coefficient which enables determination phrase fractions almost independent of the flow regime. Improvement has been achieved on the measurement accuracy of phase fractions.

  13. Comparison of Multislice Spiral CT Dual Phase and Somatosatatin Receptor Scintigraphy in the Diagnosis of Pancreas Neuroendocrine Tumors.

    Science.gov (United States)

    2016-06-10

    Objective To compare the sensitivity of multislice spiral CT dual phase and somatosatatin receptor scintigraphy (SRS) in the diagnosis of pancreas nuroendocrine tumors (pNET). Methods Totally 28 patients with pathologically confirmed pNET recieved both CT dual phase contrast and SRS and the results were compared. Results Of these 28 pNET patients,26 (92.8%) were accurately diagnosed by CT dual-phase scan and 20 (71.4%) by SRS (P=0.031).In the functioning pNET cases,the diagnosis sensitivity of CT dual phase scan and SRS was 94.1% (16/17)and 58.8% (10/17)(P=0.218). In the non-functioning pNET cases,the sensitivity was 90.9% (10/11) and 90.9% (10/11) (P=0.740).Diagnostic sensitivity of CT dual phase scan and SRS for pNET without metastasis was 90.4% (19/21) and 57.1% (12/21) (P=0.125).The sensitivity for pNET with metastasis was 100%(7/7)and 100% (7/7). Corresponding to the pathological grading,the diagnostic sensitivity of CT dual phase scanning and SRS was 84.6% (11/13) and 53.8% (7/13) for G1,100% (12/12) and 83.3% (10/12) for G2,and 100% (3/3) and 100% (3/3) for G3. The diagnostic sensitivity of CT dual phase scan and SRS for pNET with diameter less than or equal to 2.0 cm was 94.7% (18/19) and 52.6% (10/19) (P=0.008). For pNET with diameter more than 2.0 cm,the sensitivity was 92.8% (13/14) and 100% (14/14). Conclusions Compared with SRS,dual phase CT scan is more sensitive in diagnosing pNET,especially for those in lower pathological stages. For lesions sized less than or equal to 2.0 cm,SRS should be combined with other imaging examinations to minimize false negative results.

  14. Inhomogeneous Distribution of Second Phase Particles in Grain Oriented Electrical Steels

    Institute of Scientific and Technical Information of China (English)

    Yang Li; Weimin Mao; Ping Yang

    2011-01-01

    The second phase particles were observed during the whole manufacturing process of conventional grain oriented electrical steels, exhibiting that the areal density of particles in the center was obviously higher than that on the surface at each manufacturing stage. After hot rolling, the approximately equiaxed grains formed upon recrystallization were present on the sheet surface while the deformation structures were retained in the central part. Thus, the dislocation density on the surface was evidently lower than that in the center and this trend became more noticeable after the first cold rolling. Since new precipitates were mainly nucleated at dislocations during both hot rolling and annealing following cold deformation, the difference in dislocation density resulted in the inhomogeneous distribution of particles through the thickness of sheet. According to this, Goss grains, which were usually found near the surface, tended to grow up more easily during the secondary recrystallization treatment.

  15. A dual-mode phase-shift modulation control scheme for voltage multiplier based X-ray power supply

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, S [School of Electrical and Electronics Engineering, University Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Besar, R; Venkataseshaiah, C, E-mail: shahidsidu@hotmail.co [Faculty of Engineering and Technology, Multimedia University, 75450 Melaka (Malaysia)

    2010-05-15

    This paper proposes a dual-mode phase-shift modulation control scheme for series resonant inverter fed voltage multiplier (VM) based X-ray power supply. In this control scheme the outputs voltage of two parallel connected series resonant inverters are mixed before supplying to VM circuit. The output voltage of the power supply is controlled by varying the phase-shift between the output voltages of two inverters. In order to achieve quick rise of output voltage, the power supply is started with zero phase-shift and as the output voltage reaches 90% of the target voltage, the phase-shift is increased to a value which corresponds to target output voltage to prevent overshoot. The proposed control scheme has been shown to have good performance. Experimental results based on the scaled-down laboratory prototype are presented to validate the effectiveness of proposed dual-mode phase shift modulation control scheme.

  16. On the nucleation and dissolution process of Z-phase Cr(V,Nb)N in martensitic 12%Cr steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Hald, John

    2009-01-01

    Precipitation of large Z-phase particles, Cr(V,Nb)N, replacing fine MX nitrides, (V,Nb)N, has recently been identified as a major cause of premature breakdown in long-term creep strength of a number of new 9–12%Cr martensitic steels. The Z-phase precipitates slowly during long-term exposure...... at around 650 ◦C accelerated by high Cr content in the steels. It appears that the nucleation process controls the precipitation rate of Z-phase. A 12%Cr steel, which had precipitated Z-phase during long-term operation at 660 ◦C/12,000 h, was further heat treated in order to investigate the dissolution...... and reappearance processes for the Z-phase. In both cases it appears that Z-phase and MXphase are in physical contact and have a preferred crystallographic orientation relationship. The proposed nucleation mechanism is a chromium diffusion controlled transformation of MX into Z-phase, which explains the rather low...

  17. The effect of cladding speed on phase constitution and properties of AISI 431 stainless steel laser deposited coatings

    NARCIS (Netherlands)

    Hemmati, I.; Ocelik, V.; De Hosson, J. Th. M.

    2011-01-01

    Shorter processing time has given impetus to laser cladding technology and therefore in this research the AISI 431 martensitic stainless steel coatings are laser deposited at high cladding speeds, i.e. up to 117 mm/s. The analysis of phase constitution and functional properties of the coatings are p

  18. Phase Transformations in Austenitic 0Cr18Ni10Ti Steel Irradiated with High-Energy Heavy Ions

    CERN Document Server

    Hofmann, A; Semina, V K

    2000-01-01

    Radiation-induced segregation and phase transformations in 0Cr18Ni10Ti steel irradiated with high-energy heavy Ar^{+6} ions at 625^o up to 1 dpa (from 0.01 to 1 dpa) have been studied. It was found that ion irradiation accelerates carbide precipitation and EDX-analysis showed irradiation-induced segregation near grain boundaries.

  19. Effect of microstructure on the elasto-viscoplastic deformation of dual phase titanium structures

    Science.gov (United States)

    Ozturk, Tugce; Rollett, Anthony D.

    2017-08-01

    The present study is devoted to the creation of a process-structure-property database for dual phase titanium alloys, through a synthetic microstructure generation method and a mesh-free fast Fourier transform based micromechanical model that operates on a discretized image of the microstructure. A sensitivity analysis is performed as a precursor to determine the statistically representative volume element size for creating 3D synthetic microstructures based on additively manufactured Ti-6Al-4V characteristics, which are further modified to expand the database for features of interest, e.g., lath thickness. Sets of titanium hardening parameters are extracted from literature, and The relative effect of the chosen microstructural features is quantified through comparisons of average and local field distributions.

  20. A single channel input virtual dual-phase lock-in amplifier

    Science.gov (United States)

    Gao, Zhongjian; Zheng, Hua; Li, Lianhuang; Chen, Fang; Guo, Fuyuan

    2011-11-01

    In this article, it presents a suit of single channel input virtual Dual-Phase Lock-in Amplifier (DPLIA) that is constructed by a personal computer sound card and the LabVIEW software. The virtual DPLIA is low cost and convenient to implement. The implemented DPLIA could enhance the noise tolerance capability and lower the LOD of the optical signal detection system. A primary benefit of this instrument is it only needs one input channel; two internal reference signals of the digital PLL are generated in the LabVIEW software. It is easy to control and operate, the data processing results can be saved directly to disks. This instrument will be applied in other weak signal detection systems.

  1. Phase diagram of the two-dimensional O(3) model from dual lattice simulations

    CERN Document Server

    Bruckmann, Falk; Kloiber, Thomas; Sulejmanpasic, Tin

    2016-01-01

    We have simulated the asymptotically free two-dimensional O(3) model at nonzero chemical potential using the model's dual representation. We first demonstrate how the latter solves the sign (complex action) problem. The system displays a crossover at nonzero temperature, while at zero temperature it undergoes a quantum phase transition when mu reaches the particle mass (generated dynamically similar to QCD). The density follows a square root behavior universal for repulsive bosons in one spatial dimension. We have also measured the spin stiffness, known to be sensitive to the spatial correlation length, using different scaling trajectories to zero temperature and infinite size. It points to a dynamical critical exponent z=2. Comparisons to thermodynamic Bethe ansaetze are shown as well.

  2. A dual voltage control strategy for single-phase PWM converters with power decoupling function

    DEFF Research Database (Denmark)

    Tang, Yi; Qin, Zian; Blaabjerg, Frede

    2015-01-01

    converter topology based on a symmetrical half bridge circuit is proposed to decouple the ripple power so that balanced instantaneous power flow is assured between source and load, and the required dc-link capacitance can be dramatically reduced. For proper closed-loop regulation, the small signal modeling......The inherent double line ripple power in single-phase systems is adverse to the performance of power electronics converters, e.g. limited lifetime due to the requirement of large electrolytic capacitors and low voltage control bandwidth due to harmonic disturbance. In this paper, an active...... of the proposed system is presented, and a dual voltage control strategy is then proposed, which comprises one voltage loop implemented in the synchronous reference frame for active power balancing, and another one implemented in the stationary reference frame for ripple power compensation. Special attention...

  3. The influence of texture on phase transformation in metastable austenitic stainless steel

    NARCIS (Netherlands)

    Hilkhuijsen, P.

    2013-01-01

    Metastable austenitic stainless steels are used in many applications, from shavers and kitchen sinks to various applications in the food industry. The diversity in applications of this type of steels is possible due to the many positive properties of the steel. It is not only esthetically pleasing,

  4. Effect of annealing temperature on hardness, thickness and phase structure of carbonitrided 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    El-Hossary, F.M.; Negm, N.Z.; Khalil, S.M.; Abed El-Rahman, A.M.; Raaif, M. [Sohag University, Physics Department, Faculty of Science, Sohag (Egypt); Maendl, S. [Leibniz-Institute fuer Oberflaechenmodifizierung, Leipzig (Germany)

    2010-05-15

    Carbonitriding of AISI 304 austenitic stainless steel was performed at a plasma-processing power of 450 W using inductively coupled radio frequency (rf) plasma in a gas mixture of 50% N{sub 2} and 50% C{sub 2}H{sub 2}. The rate of carbonitriding, microhardness, phase structure of the compound layer, surface microstructure and cross-section morphology were studied before and after the annealing process. At the annealing temperature up to 800 C, the microhardness values of the compound zones decrease, while the associated values of the diffused zones increase. Little change was found in the thickness of the compound and diffused zones when the carbonitrided samples were annealed up to 400 C. However, at a higher annealing temperature, the thicknesses of both zones increase. The {gamma}-Fe austenite is the main crystalline phase that can be detected by X-ray diffraction. As the annealing temperature increases up to 500 C, X-ray spectra show {alpha}-Fe and Fe{sub 5}C{sub 2} phases. Nitrogen diffuses more deeply from the near surface to the interior of the treated sample as the annealing temperature increases up to 800 C and this might explain the extent of carbonitrided thickness and the enhanced microhardness of the diffused zone. (orig.)

  5. Modeling of structure of double-phase low-carbon chromium steels

    Science.gov (United States)

    Zolotarevskii, N. Yu.; Titovets, Yu. F.; Samoilov, A. N.; Hribernig, G.; Pichler, A.

    2007-01-01

    A physical model for determining the relative amount of phase components and the size of ferrite grains after decomposition of austenite in the process of cooling of double-phase steels is suggested. The main products of austenite transformation, i.e., polygonal ferrite, pearlite, bainite, and martensite, are considered. The driving forces of the transformation and the concentration of carbon on the phase surface are determined with the use of methods of computational thermodynamics. The model is based on equations of the classical theory of nucleation and growth. It allows for the structural features of the occurrence of γ → α transformation and contain some empirical parameters. The latter are determined using data of dilatometric measurements of the kinetics of austenite transformation and metallographic measurements of the size of ferrite grains. The model is used for predicting the kinetics of the transformation under the complex cooling conditions implemented by the VOEST-ALPINE STAHL LINZ GmbH rolling mill within the computer system for control of mechanical properties of hot-rolled strip.

  6. Effect of Laves phase on the creep rupture properties of P92 steel

    Energy Technology Data Exchange (ETDEWEB)

    Maddi, Lakshmiprasad, E-mail: prasadmlp@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology, Nagpur 440010 (India); GMR Institute of Technology, GMR Nagar, Rajam 532127 (India); Deshmukh, G.S.; Ballal, A.R.; Peshwe, D.R.; Paretkar, R.K. [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology, Nagpur 440010 (India); Laha, K.; Mathew, M.D. [Mechanical Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2016-06-21

    Stress rupture tests of normalized and tempered P92 (9Cr–0.5Mo–1.8 W) steel were performed in the range of 135–215 MPa at 650 °C. Effect of tempering temperature in the range of 740–780 °C on the creep rupture life was investigated. Resulting rupture times varied from 100 to 3000 h, and creep rate by one order of magnitude. In the high stress regime, lower tempering temperature resulted in the highest rupture time due to initial high dislocation density and fine laths. However, at lower stresses, highest rupture time was observed for highest tempering temperature. Formation of Laves phase (Fe{sub 2}Mo, Fe{sub 2}W) adjacent to M{sub 23}C{sub 6} carbides was responsible for increase in rupture time. Back scattered electron imaging (BSE) in scanning electron microscopy (SEM) was used to identify Laves phases, and study their distribution. Reduction in dislocation density and coarsening of laves phase precipitates result in decrease in stress exponent value ‘n’ at higher test temperatures of 650 °C.

  7. Quantification of colloidal and aqueous element transfer in soils: The dual-phase mass balance model

    Science.gov (United States)

    Bern, Carleton R.; Thompson, Aaron; Chadwick, Oliver A.

    2015-01-01

    Mass balance models have become standard tools for characterizing element gains and losses and volumetric change during weathering and soil development. However, they rely on the assumption of complete immobility for an index element such as Ti or Zr. Here we describe a dual-phase mass balance model that eliminates the need for an assumption of immobility and in the process quantifies the contribution of aqueous versus colloidal element transfer. In the model, the high field strength elements Ti and Zr are assumed to be mobile only as suspended solids (colloids) and can therefore be used to distinguish elemental redistribution via colloids from redistribution via dissolved aqueous solutes. Calculations are based upon element concentrations in soil, parent material, and colloids dispersed from soil in the laboratory. We illustrate the utility of this model using a catena in South Africa. Traditional mass balance models systematically distort elemental gains and losses and changes in soil volume in this catena due to significant redistribution of Zr-bearing colloids. Applying the dual-phase model accounts for this colloidal redistribution and we find that the process accounts for a substantial portion of the major element (e.g., Al, Fe and Si) loss from eluvial soil. In addition, we find that in illuvial soils along this catena, gains of colloidal material significantly offset aqueous elemental loss. In other settings, processes such as accumulation of exogenous dust can mimic the geochemical effects of colloid redistribution and we suggest strategies for distinguishing between the two. The movement of clays and colloidal material is a major process in weathering and pedogenesis; the mass balance model presented here is a tool for quantifying effects of that process over time scales of soil development.

  8. Phase-unwrapping approach based on dual-frequency analog structured light

    Science.gov (United States)

    Wang, Beiyi; Yu, Xiaoyang; Wu, Haibin; Zhang, Jixun; Meng, Xiaoliang

    2017-01-01

    Among the structured light 3-D measurement approaches, the multi-period analog encoded structured light (AESL) has advantages such as high resolution and high sampling rate owing to its point-to-point calculation method. However, phase unwrapping is always a problem when employing the multi-period AESL. Therefore, we propose a novel phase unwrapping approach based on dual-frequency AESL. We demonstrate the principle of the proposed phase unwrapping approach through theoretical analysis and the applicable condition for the proposed approach is determined through error analysis. We perform experiments using the proposed and classical heterodyne approaches and compare the results. The experimental results for the standard plane show that the average value of the root mean square error with the heterodyne approach is 1.08 mm, and that with the proposed approach is 0.62 mm, which is a reduction by 43%. Further, the experimental results for the complicated surfaces show that the reconstructed object obtained using the proposed approach is fine and smooth, and the detailed features are clearly displayed. The experiments verify both the accuracy and the suitability of the proposed approach.

  9. Mössbauer study of oxide phase distributions in rust formed on steel constructions near the Black Sea in Sochi

    Energy Technology Data Exchange (ETDEWEB)

    Filippov, V. P., E-mail: vpfilippov@mephi.ru; Lauer, Yu. A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation); Goloborodko, P. G.; Polyakov, A. M. [Sanatorium “Progress” (Russian Federation)

    2016-12-15

    The phase composition of the intermediate oxide layers formed on elements of steel structures at different positions relative to the sea water of the Black Sea near Sochi are investigated. The differences of the phase composition of these oxide layers are shown, depending on the location of the design details in relation to the sea and the abundancies of certain types of oxides in the studied layers are discussed.

  10. Classification of Induced Magnetic Field Signals for the Microstructural Characterization of Sigma Phase in Duplex Stainless Steels

    Directory of Open Access Journals (Sweden)

    Edgard M. Silva

    2016-07-01

    Full Text Available Duplex stainless steels present excellent mechanical and corrosion resistance properties. However, when heat treated at temperatures above 600 ∘ C, the undesirable tertiary sigma phase is formed. This phase presents high hardness, around 900 HV, and it is rich in chromium, the material toughness being compromised when the amount of this phase is not less than 4%. This work aimed to develop a solution for the detection of this phase in duplex stainless steels through the computational classification of induced magnetic field signals. The proposed solution is based on an Optimum Path Forest classifier, which was revealed to be more robust and effective than Bayes, Artificial Neural Network and Support Vector Machine based classifiers. The induced magnetic field was produced by the interaction between an applied external field and the microstructure. Samples of the 2205 duplex stainless steel were thermal aged in order to obtain different amounts of sigma phases (up to 18% in content. The obtained classification results were compared against the ones obtained by Charpy impact energy test, amount of sigma phase, and analysis of the fracture surface by scanning electron microscopy and X-ray diffraction. The proposed solution achieved a classification accuracy superior to 95% and was revealed to be robust to signal noise, being therefore a valid testing tool to be used in this domain.

  11. Low Activation Joining of SiC/SiC Composites for Fusion Applications: Thermomechanical Modeling of Dual-Phase Microstructures and Dissimilar Material Joints

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ba Nghiep; Henager, Charles H.; Kurtz, Richard J.; Ferraris, M.; Katoh, Yutai

    2016-09-30

    Finite element (FE) continuum damage mechanics (CDM) models have been developed to simulate and model dual-phase joints and cracked joints for improved analysis of SiC materials in nuclear environments. This report extends the analysis from the last reporting cycle by including preliminary thermomechanical analyses of cracked joints and implementation of dual-phase damage models.

  12. A Three-Phase Dual-Input Matrix Converter for Grid Integration of Two AC Type Energy Resources

    DEFF Research Database (Denmark)

    Liu, Xiong; Wang, Peng; Chiang Loh, Poh

    2013-01-01

    This paper proposes a novel dual-input matrix converter (DIMC) to integrate two three-phase ac type energy resources to a power grid. The proposed matrix converter is developed based on the traditional indirect matrix converter under reverse power flow operation mode, but with its six...

  13. An L-Band, Circularly Polarised, Dual-Feed, Cavity-Backed Annular Slot Antenna For Phased-Array Applications

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal; Breinbjerg, Olav

    2006-01-01

    The results of a parametric study for the development of an L-band, circularly polarised, dual-feed, cavity-backed annular slot antenna is presented. The study included detailed numerical simulations and measurements on a prototype with different ground planes, to assess the antenna’s applicability...... as an element in a small phased array antenna....

  14. Lowering of the yield ratio in solution hardened interstitial-free steel by employing transformation microstructure; Hentai soshiki wo riyoshita koyo kyoka IF ko no teikofukuhika

    Energy Technology Data Exchange (ETDEWEB)

    Sakata, K.; Okuda, K.; Seto, K.; Obara, T. [Kawasaki Steel Corp., Tokyo (Japan)

    1997-09-01

    Discussions were given for the purpose of reducing yield ratio (yield stress/tensile strength) of ultra-low carbon steel, which has been solution hardened mainly with P, by utilizing transformation microstructure resulted from dual phase annealing. An experiment was performed to investigate the relationship between kinds and amounts of solid solution elements as well as dual phase annealing conditions necessary for lowering of yield radio. The 0.10%P-1.5%MN-0.5%Si steel with a large amount of P has a high yield ratio in annealing in the single ferrite phase region, but the yield ratio decreases remarkably as a result of the dual phase annealing. Reduction of the yield ratio in the dual phase annealing corresponds with reduction in yield growth in non-conditioned materials. Reduction of the yield ratio due to the dual phase annealing may be possible even if Mn is increased, but the strengths (tensile strength and yield strength) increase largely in association with increase in {gamma} factor ratio. Dual phase distribution of ferrite and austenite as solution hardened elements and the size of dual phase temperature region were estimated by using the Thermo-Calc. High Mn steel also shows behavior similar to that in 0.10%P-1.5%Mn-0.5%Si steel with a large amount of P if no B is added. 13 refs., 9 figs., 2 tabs.

  15. A dual-frequency online PMP method with phase-shifting parallel to moving direction of measured object

    Science.gov (United States)

    Peng, Kuang; Cao, Yiping; Wu, Yingchun; Chen, Cheng; Wan, Yingying

    2017-01-01

    A dual-frequency online phase measurement profilometry (PMP) method with phase-shifting parallel to moving direction of measured object is proposed in this paper. The high-frequency fringe is used for the better modulation patterns in pixel matching and it is not modified by the measured object's surface. Based on the relative positive between the moving measured object and digital light processing (DLP), the high-frequency fringe in each dual-frequency deformed pattern after pixel matching is the same. As a result, the phase can be calculated directly by the improved Stoilov algorithm without filtering out the low-frequency component containing the measured object's height information. As there is no filtering process in phase calculation, the valid information loss can be avoided so that the accuracy of the proposed method can be guaranteed. Simulations and experiments prove the method's feasibility and precision.

  16. Inter-pulse delay optimization in dual-pulse laser induced breakdown vacuum ultraviolet spectroscopy of a steel sample in ambient gases at low pressure

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, X., E-mail: xi.jiang2@mail.dcu.ie [School of Physical Sciences, Dublin City University, Dublin (Ireland); National Centre for Plasma Science and Technology, Dublin City University, Dublin (Ireland); Hayden, P. [School of Physical Sciences, Dublin City University, Dublin (Ireland); National Centre for Plasma Science and Technology, Dublin City University, Dublin (Ireland); Laasch, R. [Institut fuer Experimentalphysik, Universitat Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Costello, J.T.; Kennedy, E.T. [School of Physical Sciences, Dublin City University, Dublin (Ireland); National Centre for Plasma Science and Technology, Dublin City University, Dublin (Ireland)

    2013-08-01

    Time-integrated spatially-resolved Laser Induced Breakdown Spectroscopy (LIBS) has been used to investigate spectral emissions from laser-induced plasmas generated on steel targets. Instead of detecting spectral lines in the visible/near ultraviolet (UV), as investigated in conventional LIBS, this work explored the use of spectral lines emitted by ions in the shorter wavelength vacuum ultraviolet (VUV) spectral region. Single-pulse (SP) and dual-pulse LIBS (DP-LIBS) experiments were performed on standardized steel samples. In the case of the double-pulse scheme, two synchronized lasers were used, an ablation laser (200 mJ/15 ns), and a reheating laser (665 mJ/6 ns) in a collinear beam geometry. Spatially resolved and temporally integrated laser induced plasma VUV emission in the DP scheme and its dependence on inter-pulse delay time were studied. The VUV spectral line intensities were found to be enhanced in the DP mode and were significantly affected by the inter-pulse delay time. Additionally, the influence of ambient conditions was investigated by employing low pressure nitrogen, argon or helium as buffer gases in the ablation chamber. The results clearly demonstrate the existence of a sharp ubiquitous emission intensity peak at 100 ns and a wider peak, in the multi-microsecond range of inter-pulse time delay, dependent on the ambient gas conditions. - Highlights: • First dual-pulse and ambient gas deep VUV LIBS plasma emission study • Optimization of inter-pulse delay time for vacuum and ambient gas environments • A sharp intensity peak implies optimal inter-pulse delay of 100 ns for all conditions. • A broad peak appears in the microsecond delay range, but only in ambient gases. • Pressure dependence implies a different enhancement process.

  17. ON THE TENSILE MECHANICAL PROPERTY OF Si-Mn TRIP STEELS AT HIGH STRAIN RATE

    Institute of Scientific and Technical Information of China (English)

    X.C. Wei; L. Li; R.Y. Fu; W. Shi

    2002-01-01

    Tensile mechanical properties of 1.6Si-1.58Mn-0.195C TRIP (transformation-inducedplasticity) steels under high strain rate and effects of DP (dual-phase) treatments werestudied and compared to the quasi-static tensile behavior. The results show that theincreasing of strain rate leads to increasing in their strengths and decreasing in theuniform elongation remarkably. Because the stable retained austenite in TRIP steelcan transform to martensite during tensile testing and the material exhibits excellentcharacteristic of transformation induced plasticity, the plastic deformation behavior isevidently improved and the combination of strength and elongation is superior to thatof dual-phase steel, although its strength is smaller than that of DP steel. However,DP treated steel shown lower elongation under dynamic tension in spite of higherstrength. A model was proposed to explain the excellent elongation rate of TRIPsteel compared with DP steel on the basis of SEM analysis and the strength of thecomponents in microstructure.

  18. Influence of deformation on structural-phase state of weld material in St3 steel

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, Alexander, E-mail: galvas.kem@gmail.ru; Ababkov, Nicolay, E-mail: n.ababkov@rambler.ru; Ozhiganov, Yevgeniy, E-mail: zhigan84@mail.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); LLC “Kuzbass Center of Welding and Control”, 33/2, Lenin Str., 650055, Kemerovo (Russian Federation); Kozlov, Eduard, E-mail: kozlov@tsuab.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Popova, Natalya, E-mail: natalya-popova-44@mail.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Institute of Strength Physics and Materials Science, SB RAS, 2/4, Akademicheskii Ave., 634021, Tomsk (Russian Federation); Nikonenko, Elena, E-mail: vilatomsk@mail.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Str., 634050, Tomsk (Russian Federation); Zboykova, Nadezhda, E-mail: tezaurusn@gmail.com; Koneva, Nina, E-mail: koneva@tsuab.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation)

    2016-01-15

    The structural-phase condition of the weld material subjected to the plastic deformation was investigated using the translucent diffraction electron microscopy method. The investigations were carried out near the joint of the weld and the base metal. The seam was done by the method of manual arc welding without artificial defects. The St3 steel was taken as the welded material. Influence of the plastic deformation on morphology, phase composition, defect structure and its parameters of weld metal was revealed. All investigations were done at the distance of 0.5 mm from the joint of the weld and the base metal at the deformation degrees from 0 to 5% and after destruction of a sample. It was established that deformation of the sample did not lead to qualitative changes in the structure (the structure is still presented by ferrite-pearlite mixture) but changed the quantitative parameters of the structure, namely, with the increase of plastic deformation a part of the pearlite component becomes more and more imperfect. In the beginning it turns into the destroyed pearlite then into ferrite, the volume fraction of pearlite is decreased. The polarization of dislocation structure takes place but it doesn’t lead to the internal stresses that can destroy the sample.

  19. Characterization and wear performance of boride phases over tool steel substrates

    Directory of Open Access Journals (Sweden)

    Edgar E Vera Cárdenas

    2016-02-01

    Full Text Available This research work was conducted to characterize boride phases, obtained from the powder-pack process, on AISI H13 and D2 steel substrates, and investigate their tribological behavior. The boriding was developed at a temperature of 1273 K with an exposure time of 8 h. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were conducted on the borided material to characterize the presence of the FeB, Fe2B, and CrB phases and the distribution of heavy elements on the surface of the substrates. The adherence of the boride layers was evaluated, in a qualitative form, through the Daimler-Benz Rockwell-C indentation technique. Sliding wear tests were then performed using a reciprocating wear test machine. All tests were conducted in dry conditions at room temperature. A frequency of 10 Hz and 15-mm sliding distance were used. The applied Hertzian pressure was 2.01 GPa. Scanning electron microscopy was used to observe and analyze the wear mechanisms. Additionally, the variation of the friction coefficient versus the number of cycles was obtained. Experimental results showed that the characteristic wear mechanism for the borided surface was plastic deformation and mild abrasive wear; for unborided substrates, cracking and spalling were observed.

  20. Solid-phase single molecule biosensing using dual-color colocalization of fluorescent quantum dot nanoprobes

    Science.gov (United States)

    Liu, Jianbo; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Liu, Wei; Wang, Dong

    2013-10-01

    The development of solid-phase surface-based single molecule imaging technology has attracted significant interest during the past decades. Here we demonstrate a sandwich hybridization method for highly sensitive detection of a single thrombin protein at a solid-phase surface based on the use of dual-color colocalization of fluorescent quantum dot (QD) nanoprobes. Green QD560-modified thrombin binding aptamer I (QD560-TBA I) were deposited on a positive poly(l-lysine) assembled layer, followed by bovine serum albumin blocking. It allowed the thrombin protein to mediate the binding of the easily detectable red QD650-modified thrombin binding aptamer II (QD650-TBA II) to the QD560-TBA I substrate. Thus, the presence of the target thrombin can be determined based on fluorescent colocalization measurements of the nanoassemblies, without target amplification or probe separation. The detection limit of this assay reached 0.8 pM. This fluorescent colocalization assay has enabled single molecule recognition in a separation-free detection format, and can serve as a sensitive biosensing platform that greatly suppresses the nonspecific adsorption false-positive signal. This method can be extended to other areas such as multiplexed immunoassay, single cell analysis, and real time biomolecule interaction studies.The development of solid-phase surface-based single molecule imaging technology has attracted significant interest during the past decades. Here we demonstrate a sandwich hybridization method for highly sensitive detection of a single thrombin protein at a solid-phase surface based on the use of dual-color colocalization of fluorescent quantum dot (QD) nanoprobes. Green QD560-modified thrombin binding aptamer I (QD560-TBA I) were deposited on a positive poly(l-lysine) assembled layer, followed by bovine serum albumin blocking. It allowed the thrombin protein to mediate the binding of the easily detectable red QD650-modified thrombin binding aptamer II (QD650-TBA II) to

  1. Application of dual phase imaging of 11C-acetate positron emission tomography on differential diagnosis of small hepatic lesions.

    Directory of Open Access Journals (Sweden)

    Li Huo

    Full Text Available OBJECTIVE: Previously we observed that dual phase 11C-acetate positron emission tomography (AC-PET could be employed for differential diagnosis of liver malignancies. In this study, we prospectively evaluated the effect of dual phase AC-PET on differential diagnosis of primary hepatic lesions of 1-3 cm in size. METHODS: 33 patients having primary hepatic lesions with size of 1-3 cm in diameter undertook dual phase AC-PET scans. Procedure included an early upper-abdomen scan immediately after tracer injection and a conventional scan in 11-18 min. The standardized uptake value (SUV was calculated for tumor (SUVT and normal tissue (SUVB, from which 11C-acetate uptake ratio (as lesion against normal liver tissue, SUVT/SUVB in early imaging (R1, conventional imaging (R2, and variance between R2 and R1 (ΔR were derived. Diagnoses based on AC-PET data and histology were compared. Statistical analysis was performed with SPSS 19.0. RESULTS: 20 patients were found to have HCC and 13 patients had benign tumors. Using ΔR>0 as criterion for malignancy, the accuracy and specificity were significantly increased comparing with conventional method. The area under ROC curve (AUC for R1, R2, and ΔR were 0.417, 0.683 and 0.831 respectively. Differential diagnosis between well-differentiated HCCs and benign lesions of FNHs and hemangiomas achieved 100% correct. Strong positive correlation was also found between R1 and R2 in HCC (r2 = 0.55, P<0.001. CONCLUSIONS: Dual phase AC-PET scan is a useful procedure for differential diagnosis of well-differentiated hepatocellular carcinoma and benign lesions. The dynamic changes of 11C-acetate uptake in dual phase imaging provided key information for final diagnosis.

  2. Chemical gradients across phase boundaries between martensite and austenite in steel studied by atom probe tomography and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Dmitrieva, O.; Ponge, D.; Inden, G.; Millan, J.; Choi, P. [Max-Planck-Institut fuer Eisenforschung, Max-Planck-Str. 1, 40237 Duesseldorf (Germany); Sietsma, J. [Delft University of Technology, Faculty 3mE, Dept. MSE, 2628 CD Delft (Netherlands); Raabe, D., E-mail: d.raabe@mpie.de [Max-Planck-Institut fuer Eisenforschung, Max-Planck-Str. 1, 40237 Duesseldorf (Germany)

    2011-01-15

    Partitioning at phase boundaries of complex steels is important for their properties. We present atom probe tomography results across martensite/austenite interfaces in a precipitation-hardened maraging-TRIP steel (12.2 Mn, 1.9 Ni, 0.6 Mo, 1.2 Ti, 0.3 Al; at.%). The system reveals compositional changes at the phase boundaries: Mn and Ni are enriched while Ti, Al, Mo and Fe are depleted. More specific, we observe up to 27 at.% Mn in a 20 nm layer at the phase boundary. This is explained by the large difference in diffusivity between martensite and austenite. The high diffusivity in martensite leads to a Mn flux towards the retained austenite. The low diffusivity in the austenite does not allow accommodation of this flux. Consequently, the austenite grows with a Mn composition given by local equilibrium. The interpretation is based on DICTRA and mixed-mode diffusion calculations (using a finite interface mobility).

  3. Effect of second phase particles topology on the onset temperature of abnormal grain growth in Fe - 3%Si steels

    Directory of Open Access Journals (Sweden)

    Stoyka, V.

    2008-01-01

    Full Text Available The relations between regimes of dynamic annealing, state of secondary particles system and the onset temperature of abnormal grain growth are investigated. Two distinguish types of Fe-3%Si grain-oriented steels, after one and two stage cold rolling, were studied. The second phase particles remain unaffected in first type of steel during the heat treatment. Vice versa, the increased density of second phases was observed after annealing in the second type of the investigated materials. It is shown that start/onset of abnormal grain growth strongly depends on both volume fraction of second phase particles and annealing temperature. Texture and magnetic properties of the investigated samples are investigated within the current study.

  4. Precipitation of Laves phase Fe2Mo type in HSLA steel with copper addition and high content of molybdenum

    Directory of Open Access Journals (Sweden)

    S. Pytel

    2010-07-01

    Full Text Available The results of mechanical properties and microstructure of low-carbon copper bearing steel after quenching and tempering at temperaturerange of processing precipitation of particles rich in copper and particles intermetallic phase are presented in this paper. When content molybdenum increases in tempering temperature range from 550°C to 600°C that decrease of the impact energy measured at roomtemperature was observed. Microstructure analysis was conducted by transmission electron microscope (TEM and was disclosed theoccurrence of Fe2Mo Laves phase on crystallites boundaries of retained austenite. Observed sudden drop of ductility in higher-molybdenum content steels (1,88 % and 2,94 % should be connected with occurrence precipitation processes of the hard and brittle Laves phase in range of discussion tempering temperatures.

  5. Atomic resolution investigations of phase transformation from TaN to CrTaN in a steel matrix

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Hald, John

    2012-01-01

    , thus preserving long-term creep strength. This can be done by alloying with Ta instead of Nb and V. Recent investigations have indicated a direct transformation of MN into CrMN to take place, not the traditional nucleation/dissolution process. In this paper atomic resolution microscopy shows how Cr......In development of 12%Cr high temperature steels used for fossil fired power plants, the precipitation of large Z-phase particles, CrMN, has been identified as a major problem since they replace small and finely distributed MN particles. This causes a premature breakdown in the longterm creep...... strength of the steel. The Cr content promotes Z-phase precipitation, making MN strengthening of these materials unfeasible, since 12%Cr is necessary for oxidation resistance. The authors have suggested an acceleration of Z-phase precipitation to obtain a fine and stable distribution of CrMN instead of MN...

  6. Detection of Secondary Phases in UNS S32760 Superduplex Stainless Steel by Destructive and Non-destructive Techniques

    Science.gov (United States)

    Argandona, G.; Biezma, M. V.; Berrueta, J. M.; Berlanga, C.; Ruiz, A.

    2016-12-01

    Duplex stainless steels (DSS), with a microstructure of an approximately equal mixture of ferrite ( α) and austenite ( γ) phases, are susceptible to the formation of undesirable phases if manufacturing processes are not carefully controlled. In particular, sigma phase (σ) is a Cr- and Mo-rich intermetallic phase, formed generally when DSS are by the temperature range from 600 to 900 °C, even for very short time periods. The precipitation of this phase induces detrimental effects in mechanical and corrosion resistance properties in the material, and even a low volume percentage of σ phase can significantly affect these properties. The current paper presents the effect of thermal treatments on UNS S32760 superduplex stainless steel seamless tubes, applied in order to promote the precipitation of different σ phase percentages in a ferrite/austenite microstructure. The detection and quantification of the σ phase using non-destructive ultrasounds testing has been one of the most relevant events of this study that contributes to improving the correlation of the results obtained using destructive and non-destructive techniques for the quantification of undesirable phases in superduplex seamless tubes during the manufacturing process.

  7. E, B, μ, T phase structure of the D3/D7 holographic dual

    Science.gov (United States)

    Evans, Nick; Gebauer, Astrid; Kim, Keun-Young

    2011-05-01

    The large N mathcal{N} = 4 gauge theory with quenched mathcal{N} = 2 quark matter displays chiral symmetry breaking in the presence of a magnetic field. We previously studied the temperature and chemical potential phase structure of this theory in the grand canonical ensemble-here we, in addition, include the effect of an electric field which acts to counter chiral symmetry breaking by dissociating mesons. We compute using the gravity dual based on the D3/probe-D7 brane system. The theory displays two transition at one of which chiral symmetry is restored. At the other transition density switches on, the mesons of the theory become unstable and a current forms, making it a conductor-insulator transition. Through the temperature, electric field, chemical potential volume (at fixed magnetic field parallel to the electric field) these transitions can coincide or separate at critical points, and be first order or second order. We map out this full phase structure which provides varied computable examples relevant to strongly coupled gauge theories and potentially condensed matter systems.

  8. E, B, \\mu, T Phase Structure of the D3/D7 Holographic Dual

    CERN Document Server

    Evans, Nick; Kim, Keun-Young

    2011-01-01

    The large N_c N=4 gauge theory with quenched N=2 quark matter displays chiral symmetry breaking in the presence of a magnetic field. We previously studied the temperature and chemical potential phase structure of this theory in the grand canonical ensemble - here we, in addition, include the effect of an electric field which acts to counter chiral symmetry breaking by disassociating mesons. We compute using the gravity dual based on the D3/probe-D7 brane system. The theory displays two transition at one of which chiral symmetry is restored. At the other transition density switches on, the mesons of the theory become unstable and a current forms, making it a conductor-insulator transition. Through the temperature, electric field, chemical potential volume (at fixed magnetic field parallel to the electric field) these transitions can coincide or separate at critical points, and be first order or second order. We map out this full phase structure which provides varied computable examples relevant to strongly cou...

  9. Noise Measurements Of Resistors With The Use Of Dual-Phase Virtual Lock-In Technique

    Directory of Open Access Journals (Sweden)

    Stadler Adam Witold

    2015-12-01

    Full Text Available Measurement of low-frequency noise properties of modern electronic components is a very demanding challenge due to the low magnitude of a noise signal and the limit of a dissipated power. In such a case, an ac technique with a lock-in amplifier or the use of a low-noise transformer as the first stage in the signal path are common approaches. A software dual-phase virtual lock-in (VLI technique has been developed and tested in low-frequency noise studies of electronic components. VLI means that phase-sensitive detection is processed by a software layer rather than by an expensive hardware lock-in amplifier. The VLI method has been tested in exploration of noise in polymer thick-film resistors. Analysis of the obtained noise spectra of voltage fluctuations confirmed that the 1/f noise caused by resistance fluctuations is the dominant one. The calculated value of the parameter describing the noise intensity of a resistive material, C = 1·10−21 m3, is consistent with that obtained with the use of a dc method. On the other hand, it has been observed that the spectra of (excitation independent resistance noise contain a 1/f component whose intensity depends on the excitation frequency. The phenomenon has been explained by means of noise suppression by impedances of the measurement circuit, giving an excellent agreement with the experimental data.

  10. Intensity and phase noise correlations in a dual-frequency VECSEL operating at telecom wavelength

    CERN Document Server

    De, Syamsundar; Bouchoule, Sophie; Alouini, Mehdi; Bretenaker, Fabien

    2015-01-01

    The amplitude and phase noises of a dual-frequency vertical-external-cavity surface-emitting laser (DF-VECSEL) operating at telecom wavelength are theoretically and experimentally investigated in detail. In particular, the spectral behavior of the correlation between the intensity noises of the two modes of the DF-VECSEL is measured. Moreover, the correlation between the phase noise of the radio-frequency (RF) beatnote generated by optical mixing of the two laser modes with the intensity noises of the two modes is investigated. All these spectral behaviors of noise correlations are analyzed for two different values of the nonlinear coupling between the laser modes. We find that to describe the spectral behavior of noise correlations between the laser modes, it is of utmost importance to have a precise knowledge about the spectral behavior of the pump noise, which is the dominant source of noise in the frequency range of our interest (10 kHz to 35 MHz). Moreover, it is found that the noise correlation also dep...

  11. Technical Note: Simple formulations and solutions of the dual-phase diffusive transport for biogeochemical modeling

    Directory of Open Access Journals (Sweden)

    J. Y. Tang

    2014-01-01

    Full Text Available Representation of gaseous diffusion in variably saturated near-surface soils is becoming more common in land biogeochemical models, yet the formulations and numerical solution algorithms applied vary widely. We present three different but equivalent formulations of the dual-phase (gaseous and aqueous tracer diffusion transport problem that is relevant to a wide class of volatile tracers in land biogeochemical models. Of these three formulations (i.e., the gas-primary, aqueous-primary, and bulk tracer based formulations, we contend the gas-primary formulation is the most convenient for modeling tracer dynamics in biogeochemical models. We then provide finite volume approximation to the gas-primary equation and evaluate its accuracy against three analytical models: one for steady-state soil CO2 dynamics, one for steady-state soil CO2 dynamics, and one for transient tracer diffusion from a constant point source into two different sequentially aligned medias. All evaluations demonstrated good accuracy of the numerical approximation. We expect our result will standardize an efficient mechanistic numerical method for solving relatively simple, multi-phase, one-dimensional diffusion problems in land models.

  12. Inter-pulse delay optimization in dual-pulse laser induced breakdown vacuum ultraviolet spectroscopy of a steel sample in ambient gases at low pressure

    Science.gov (United States)

    Jiang, X.; Hayden, P.; Laasch, R.; Costello, J. T.; Kennedy, E. T.

    2013-08-01

    Time-integrated spatially-resolved Laser Induced Breakdown Spectroscopy (LIBS) has been used to investigate spectral emissions from laser-induced plasmas generated on steel targets. Instead of detecting spectral lines in the visible/near ultraviolet (UV), as investigated in conventional LIBS, this work explored the use of spectral lines emitted by ions in the shorter wavelength vacuum ultraviolet (VUV) spectral region. Single-pulse (SP) and dual-pulse LIBS (DP-LIBS) experiments were performed on standardized steel samples. In the case of the double-pulse scheme, two synchronized lasers were used, an ablation laser (200 mJ/15 ns), and a reheating laser (665 mJ/6 ns) in a collinear beam geometry. Spatially resolved and temporally integrated laser induced plasma VUV emission in the DP scheme and its dependence on inter-pulse delay time were studied. The VUV spectral line intensities were found to be enhanced in the DP mode and were significantly affected by the inter-pulse delay time. Additionally, the influence of ambient conditions was investigated by employing low pressure nitrogen, argon or helium as buffer gases in the ablation chamber. The results clearly demonstrate the existence of a sharp ubiquitous emission intensity peak at 100 ns and a wider peak, in the multi-microsecond range of inter-pulse time delay, dependent on the ambient gas conditions.

  13. Springback analysis of ultra high strength steel

    Science.gov (United States)

    Tenma, Kenji; Kina, Futoshi; Suzuki, Wataru

    2013-12-01

    It is an inevitable trend in the automotive industry to apply more and more high strength steels and even ultra-high strength steels. Even though these materials are more difficult to process the development time of forming tools must be reduced. In order to keep the development time under control, simulation tools are used to verify the forming process in advance. At Aoi Machine Industry a project has been executed to accurately simulate springback of ultra-high strength steels in order to reduce the tool tryout time. In the first phase of the project the simulation settings were optimized based on B-Pillar model A made of Dual Phase 980. In the second phase, it was verified with B-Pillar model B whether these simulation settings were usable as general setting. Results showed that with the right settings it is very well possible to accurately simulate springback of ultra-high strength steels. In the third phase the project the stamping of a B-Pillar of Dual Phase 1180 was studied.

  14. A Prospective Comparative Study of Parathyroid Dual-Phase Scintigraphy, Dual-Isotope Subtraction Scintigraphy, 4D-CT, and Ultrasonography in Primary Hyperparathyroidism

    DEFF Research Database (Denmark)

    Krakauer, Martin; Wieslander, Bente; Myschetzky, Peter Sand

    2016-01-01

    PURPOSE: Preoperative localization of the diseased parathyroid gland(s) in primary hyperparathyroidism allows for minimally invasive surgery. This study was designed to establish the optimal first-line preoperative imaging modality. PATIENTS AND METHODS: Ninety-one patients were studied...... standard. RESULTS: Ninety-seven hyperfunctioning parathyroid glands (HPGs) were identified by the reference standard. Sensitivity and specificity for subtraction PS, dual-phase PS, 4D-CT, and US were 93%, 65%, 58%, and 57% as well as 99%, 99.6%, 86%, and 95%, respectively. Interrater agreement...

  15. Long-term creep deformation characteristics of advanced ferritic steels for USC power plants

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizawa, M. [Corporate Research and Development Laboratories, Sumitomo Metal Industries, Ltd., 1-8 Fuso-cho, Amagasaki, Hyogo, 660-0891 (Japan); Igarashi, M. [Corporate Research and Development Laboratories, Sumitomo Metal Industries, Ltd., 1-8 Fuso-cho, Amagasaki, Hyogo, 660-0891 (Japan)

    2007-01-15

    Creep rupture and deformation behavior of T122-type steels with different matrix phases such as {alpha}' (martensite) and {alpha}{sup '}+{delta} (martensite and delta-ferrite) at different stress levels has been studied using creep testing and a detailed FE-STEM microscopy. Long-term creep rupture strength of the dual phase steel is found to be lower than that expected from the short-term creep testing. Fine grain microstructure enhances the creep deformation of the dual phase steel at lower stress region, but is not the major factor on the degradation. Decrease in fine MX and unequal distribution of MX in the ferrite matrix are found to be the major causes of the strength degradation in the dual phase steel with the higher Cr content. It is thus concluded that the heterogeneous creep deformation is much more pronounced at lower stress level in the dual phase steel, which is due to inhomogeneous microstructure consisting of {alpha}{sup '}+{delta} phase matrix and the relevant heterogeneous distribution of fine precipitates such as MX and M{sub 23}C{sub 6} in the {delta}-ferrite matrix and near the interface between {delta}/{gamma}.

  16. Long-term creep deformation characteristics of advanced ferritic steels for USC power plants

    Energy Technology Data Exchange (ETDEWEB)

    M. Yoshizawa; M. Igarashi [Sumitomo Metal Industries, Ltd., Hyogo (Japan). Corporate Research and Development Laboratories

    2007-01-15

    Creep rupture and deformation behavior of T122-type steels with different matrix phases such as {alpha}{prime} (martensite) and {alpha}{prime}+{delta} (martensite and delta-ferrite) at different stress levels has been studied using creep testing and a detailed FE-STEM microscopy. Long-term creep rupture strength of the dual phase steel is found to be lower than that expected from the short-term creep testing. Fine grain microstructure enhances the creep deformation of the dual phase steel at lower stress region, but is not the major factor on the degradation. Decrease in fine MX and unequal distribution of MX in the ferrite matrix are found to be the major causes of the strength degradation in the dual phase steel with the higher Cr content. It is thus concluded that the heterogeneous creep deformation is much more pronounced at lower stress level in the dual phase steel, which is due to inhomogeneous microstructure consisting of {alpha}{prime}+{delta} phase matrix and the relevant heterogeneous distribution of fine precipitates such as MX and M{sub 23}C{sub 6} in the {delta}ferrite matrix and near the interface between {delta}/{gamma}.

  17. Damage characterization of high-strength multiphase steels

    Science.gov (United States)

    Heibel, S.; Nester, W.; Clausmeyer, T.; Tekkaya, A. E.

    2016-11-01

    High-strength steels show an entirely different material behavior than conventional deep-drawing steels. This fact is caused among others by the multiphase nature of their structure. The Forming Limit Diagram as the classic failure criterion in forming simulation is only partially suitable for this class of steels. An improvement of the failure prediction can be obtained by using damage mechanics. Therefore, an exact knowledge of the material-specific damage is essential for the application of various damage models. In this paper the results of microstructure analysis of a dual-phase steel and a complex-phase steel with a tensile strength of 1000 MPa are shown comparatively at various stress conditions. The objective is to characterize the basic damage mechanisms and based on this to assess the crack sensitivity of both steels. First a structural analysis with regard to non-metallic inclusions, the microstructural morphology, phase identification and the difference in microhardness between the structural phases is carried out. Subsequently, the development of the microstructure at different stress states between uniaxial and biaxial tension is examined. The damage behavior is characterized and quantified by the increase in void density, void size and the quantity of voids. The dominant damage mechanism of the dual-phase steel is the void initiation at phase boundaries, within harder structural phases and at inclusions. In contrast the complex-phase steel shows a significant growth of a smaller amount of voids which initiate only at inclusions. To quantify the damage tolerance and the susceptibility of cracking the criterion of the fracture forming limit line (FFL) is used. The respective statements are supported by results of investigations regarding the edge-crack sensitivity.

  18. SIR phasing by combination of SOLVE/RESOLVE and dual-space fragment extension involving OASIS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new phasing procedure has been proposed for dealing with single isomorphous replacement (SIR) x-ray diffraction data. The procedure combines SOLVE/RESOLVE with the dual-space fragment extension involving OASIS. Two sets of SIR data at 0.28 nm resolution taken from the protein (R)-phycoerythrin (PDB code: 1LIA) were used in the test.For one of the two SIR data sets, a default run of SOLVE/RESOLVE based on the heavy-atom substructure found by SHLEXD led automatically to an interpretable electron density map. OASIS could not effectively improve the result.For the other set of SIR data, SOLVE/RESOLVE resulted in a fragmented model consisting of 454 of the total 668 residues, in which only 29 residues were docked into the sequence. Based on this model, 7 iteration cycles of OASIS-DM-RESOLVE (build only) yielded automatically a model of 547 residues with 133 residues docked into the sequence. The overall-averaged phase error decreased considerably and the quality of electron density map was improved significantly.Two more cycles of iterative OASIS-DM-RESOLVE were carried out, in which the output phases and figures of merit from DM were merged with that from the original run of SOLVE/RESOLVE before they were passed onto RESOLVE (build only). This led automatically to a model containing 452 residues with 173 docked into the sequence. The resultant electron density map is manually traceable. It is concluded that when results of SOLVE/RESOLVE are not sufficiently satisfactory, the combination of SOLVE/RESOLVE and OASIS-DM-RESOLVE (build only) may significantly improve them.

  19. Development of a carburizing and quenching simulation tool: A material model for low carbon steels undergoing phase transformations

    Energy Technology Data Exchange (ETDEWEB)

    Bammann, D.; Prantil, V.; Kumar, A. [Sandia National Labs., Livermore, CA (United States)] [and others

    1996-06-24

    An internal state variable formulation for phase transforming alloy steels is presented. We have illustrated how local transformation plasticity can be accommodated by an appropriate choice for the corresponding internal stress field acting between the phases. The state variable framework compares well with a numerical micromechanical calculation providing a discrete dependence of microscopic plasticity on volume fraction and the stress dependence attributable to a softer parent phase. The multiphase model is used to simulate the stress state of a quenched bar and show qualitative trends in the response when the transformation phenomenon is incorporated on the length scale of a global boundary value problem.

  20. The effect of σ-phase precipitation at 800°C on the corrosion resistance in sea-water of a high alloyed duplex stainless steel

    NARCIS (Netherlands)

    Wilms, M.E.; Gadgil, V.J.; Krougman, J.M.; Ijsseling, F.P.

    1994-01-01

    Super-duplex stainless steels are recently developed high alloyed stainless steels that combine good mechanical properties with excellent corrosion resistance. Because of a high content of chromium and molybdenum, these alloys are susceptible to σ-phase precipitation during short exposure to

  1. Precipitation behavior of Z phase after long-term creep in high chromium ferritic heat resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Sawada, K.; Kushima, H.; Kimura, K. [National Institute for Materials Science, Tsukuba (Japan). Materials Reliability Center

    2006-07-01

    The precipitation behavior of the Z phase was investigated after long-term creep exposure in ASME-T91, T92, T122 without {delta}-ferrite, and T122 with {delta}-ferrite through elemental mapping using EF-TEM. The Z phase was identified by comparing the Cr map with the V map. Most of the Z phase was observed around prior austenite grain boundaries and/or packet boundaries in all of the steels examined. In T122 with {delta}-ferrite, the Z phase also precipitates around the {delta}-ferrite. In particular, the number of MX carbonitrides was very small in T122 with a large amount of the Z phase. The main metallic composition of the Z phase in T91 was the same as that in T92. In T122, the Z phase contained a lower Nb content. The main metallic composition of the Z phase around the {delta}-ferrite was the same as that in the other areas. There was no large difference in the size distribution of the Z phase among the steels. The mean diameter of the Z phases for T122 with {delta}-ferrite was relatively large in spite of a shorter creep exposure in contrast with T91 and T92. The number density of the Z phases increased with increasing creep exposure time except in the case of T91. The order of the number density was T122 with {delta}-ferrite, T91, T122 without {delta}-ferrite, and T92. In crept samples, the amount of Z phase in the gauge portion was higher than that in the grip portion, meaning that stress and/or strain promotes the formation of a Z phase during creep exposure. (orig.)

  2. Micromechanics of plastic deformation and phase transformation in a three-phase TRIP-assisted advanced high strength steel: Experiments and modeling

    Science.gov (United States)

    Srivastava, Ankit; Ghassemi-Armaki, Hassan; Sung, Hyokyung; Chen, Peng; Kumar, Sharvan; Bower, Allan F.

    2015-05-01

    The micromechanics of plastic deformation and phase transformation in a three-phase advanced high strength steel are analyzed both experimentally and by microstructure-based simulations. The steel examined is a three-phase (ferrite, martensite and retained austenite) quenched and partitioned sheet steel with a tensile strength of ~980 MPa. The macroscopic flow behavior and the volume fraction of martensite resulting from the austenite-martensite transformation during deformation were measured. In addition, micropillar compression specimens were extracted from the individual ferrite grains and the martensite particles, and using a flat-punch nanoindenter, stress-strain curves were obtained. Finite element simulations idealize the microstructure as a composite that contains ferrite, martensite and retained austenite. All three phases are discretely modeled using appropriate crystal plasticity based constitutive relations. Material parameters for ferrite and martensite are determined by fitting numerical predictions to the micropillar data. The constitutive relation for retained austenite takes into account contributions to the strain rate from the austenite-martensite transformation, as well as slip in both the untransformed austenite and product martensite. Parameters for the retained austenite are then determined by fitting the predicted flow stress and transformed austenite volume fraction in a 3D microstructure to experimental measurements. Simulations are used to probe the role of the retained austenite in controlling the strain hardening behavior as well as internal stress and strain distributions in the microstructure.

  3. AISI/DOE Technology Roadmap Program: Characterization of Fatigue and Crash Performance of New Generation High Strength Steels for Automotive Applications

    Energy Technology Data Exchange (ETDEWEB)

    Brenda Yan; Dennis Urban

    2003-04-21

    A 2-year project (2001-2002) to generate fatigue and high strain data for a new generation of high strength steels (HSS) has been completed in December 2002. The project tested eleven steel grades, including Dual Phase (DP) steels, Transformation-Induced Plasticity (TRIP) steels, Bake Hardenable (BH) steels, and conventional High Strength Low Alloy (HSLA) steels. All of these steels are of great interest in automotive industry due to the potential benefit in weight reduction, improved fuel economy, enhanced crash energy management and total system cost savings. Fatigue behavior includes strain controlled fatigue data notch sensitivity for high strength steels. High strain rate behavior includes stress-strain data for strain rates from 0.001/s to 1000/s, which are considered the important strain rate ranges for crash event. The steels were tested in two phases, seven were tested in Phase 1 and the remaining steels were tested in Phase. In a addition to the fatigue data and high st rain rate data generated for the steels studied in the project, analyses of the testing results revealed that Advanced High Strength Steels (AHSS) exhibit significantly higher fatigue strength and crash energy absorption capability than conventional HSS. TRIP steels exhibit exceptionally better fatigue strength than steels of similar tensile strength but different microstructure, for conditions both with or without notches present

  4. Caracterización de aceros dual-phase obtenidos por laminación en caliente

    Directory of Open Access Journals (Sweden)

    Houbaert, Y.

    2011-02-01

    Full Text Available Samples were obtained from C-Mn-Si steel available in the market. Through a hot rolling and coiling process, it was possible to obtain Dual-Phase steel with microstructural and mechanical properties in the theoretical range typical of this material. The thermomechanical process consisted of a strong reduction by multiples pass of hot rolling at temperatures above Ar3, controlled-cooling the sheets during 5 s (at a rate of 20 °C/s in the equilibrium range α+γ. Temperature Ar3 measured by differential scanning calorimetry was 890 °C. Quenching was then carried out in the coiling temperatures range (500-675 °C, cooling the samples in accordance to an established curve that corresponds to the actual cooling curve of a coil. The microstructural characterization of the samples obtained was carried out by optical microscopy, scanning electron microscopy and atomic force microscopy. Additionally, texture measurements were carried out by X-ray diffraction in order to study the resulting orientations due to the finishing rolling temperature and coiling temperature, determining the influence on these parameters of the different texture components. The microstructural results were complemented with the normal and planar anisotropy indexes measured in according to the ASTM E-517 standard. The intensities of the different texture components were correlated with the values of anisotropy indexes, finding that it is possible to obtain only a slightly enhancement in the normal anisotropy index through an appropriate combination of finish rolling and coiling temperatures.

    Se tomaron muestras de acero al C-Mn-Si disponible en el mercado y mediante un proceso de laminación en caliente y bobinado, se obtuvo acero Dual Phase con microestructura y propiedades mecánicas dentro del rango teórico esperado de este material. El proceso termomecánico consistió en producir una fuerte reducción a temperaturas mayores a Ar3

  5. Ultrasound-assisted phase-transfer catalysis: benzoylation of sodium 4-acetylphenoxide by dual-site phase-transfer catalyst in a tri-liquid system.

    Science.gov (United States)

    Yang, Hung-Ming; Chiu, Chun-Cheng

    2011-01-01

    A novel dual-site phase-transfer catalyst (PTC) was prepared and used to conduct the benzoylation of sodium 4-acetylphenoxide by ultrasound-assisted third-liquid phase-transfer catalysis. The catalyst 1,4-bis(tributylammoniomethyl)benzene dibromide (BTBAMBB) was synthesized from the reaction of p-xylylene dibromide and tributylamine in toluene at 70°C. The dual-site PTC was employed to form the third-liquid phase by extra addition of 0.04-0.05 mol of NaCl into 10 cm(3) of water. In the condition of 0.0425 mol of NaCl at 30°C, the catalytic intermediate in the third-liquid phase reached a maximum value. Almost 80% of the catalyst was transferred from the aqueous phase into the third-liquid phase. The distributions of the catalytic intermediate and dual-site PTC between phases and the kinetics of benzoylation of sodium 4-acetylphenoxide catalyzed by BTBAMBB with ultrasound irradiation were performed. The pseudo-first-order kinetic equation was applied to describe the overall reaction. Under ultrasound irradiation (28 kHz/300 W) in a batch reactor, the yield of product 4-acetylphenyl benzoate in the organic phase was 98.1% in 2 min at 30°C and 250 rpm with the apparent rate constant k(app) to be 0.0075 s(-1), which was 6 times faster than that without using ultrasound (yield=14.4%, k(app)=0.0013 s(-1)). The present study provides a green method to synthesize esters by ultrasound-assisted third-liquid phase-transfer catalysis.

  6. Effect of casting technology on microstructure and phases of high carbon high speed steel

    Directory of Open Access Journals (Sweden)

    Zhang Tianming

    2011-05-01

    Full Text Available The as-cast microstructures of high carbon high speed steels (HC-HSS made by sand casting, centrifugal casting and electromagnetic centrifugal casting, respectively, were studied by using of optical microscopy (OM and D/max2200pc X-ray diffraction. The results show that the microstructure of as-cast HC-HSS is dominated by alloy carbides (W2C, VC, Cr7C3, martensite and austenite. The centrifugal casting and electromagnetic centrifugal casting apparently improve the solidification structure of HC-HSS. With the increase of magnetic intensity (B, the volume fraction of austenite in the HC-HSS solidification structure increases significantly while the eutectic ledeburite decreases. Moreover, the secondary carbides precipitated from the austenite are finer with more homogeneous distribution in the electromagnetic centrifugal castings. It has also been found that the lath of eutectic carbide in ledeburite becomes finer and carbide phase spacing in eutectic ledeburite increases along with the higher magnetic field strength.

  7. Solidification microstructures and phase transformations in Al-Ti-Si-Mn deoxidized steel weld metals

    Science.gov (United States)

    Kluken, A. O.; Grong, Ø.; Rørvik, G.

    1990-07-01

    The present investigation is concerned with basic studies of solidification mechanisms in Al-Ti-Si-Mn deoxidized steel weld metals. Assessment of the weld metal solidification micro-structures was done on the basis of optical microscopy in combination with secondary ion mass spectrometry (SIMS), while both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for characterization of indigenous oxide inclusions. It is shown that nonmetallic inclusions play a critical role in the development of the weld metal columnar grain structure by acting as inert substrates for nucleation of delta ferrite ahead of the advancing interface. The nucleation potency of the oxides increases in the order SiO2-MnO, Al2O3-Ti2O3-SiO2-MnO, A12O3, reflecting a corresponding increase in the inclusion/liquid interfacial energy. Moreover, a shift in the peritectic reaction (which facilitates growth of the austenite grains across the phosphorus-rich boundaries of the primary delta ferrite phase) has been observed in the presence of A12O3 inclusions. Indications are that the resulting decrease in the local phosphorus concentrations at the austenite grain boundaries will strongly alter the kinetics of the subsequent solid-state transformation reactions by promoting growth of grain boundary ferrite sideplates at the expense of intragranularly nucleated acicular ferrite.

  8. Surface oxidation and phase transformation of the stainless steel by hybrid laser-waterjet impact

    Science.gov (United States)

    Weiss, L.; Aillerie, M.; Tazibt, A.; Tidu, A.

    2014-09-01

    Hybrid jets (laser guided by water jet) are commonly used in the area of microelectronics for cutting thin wafer plates and for the design of special pieces. In this context, the hybrid jet works with a low power and low pressure. Efforts are made to apply and to improve this hybrid technology for cutting thicker metallic materials. In order to facilitate this development, we have studied the effects induced by a water jet-laser system coupled to the same point on a metallic material. The pressure of the water jet is about 1 MPa and the power of the laser source is about 400 W, which is much higher than the actual hybrid jet power. As a result, in the case of 301 L steel plates, we have noticed the formation of a magnetite layer around the cut in accordance with the high temperature reactions between water and iron, but, surprisingly, in this case, the reaction is practically instantaneous. A small percentage of hematite also appears, from a secondary reaction of reduction of magnetite. By using different techniques (Raman spectroscopy, optical microscopy, SEM, XRD…) we have observed, firstly, that the width of the oxidized zone is proportional to the cutting speed and on the other hand, that there exists a phase transformation in a small heat-affected zone, consistent with the hybrid jets literature.

  9. Cyclic Partial Phase Transformations In Low Alloyed Steels: Modeling and Experiments

    NARCIS (Netherlands)

    Chen, H.

    2013-01-01

    Mechanical properties of low alloyed steels are directly determined by their microstructures. Thanks to versatility in their microstructures, the mechanical properties of low alloyed steels are much more adjustable than other materials. In the industry, one of the most effective ways to obtain the m

  10. Cyclic Partial Phase Transformations In Low Alloyed Steels: Modeling and Experiments

    NARCIS (Netherlands)

    Chen, H.

    2013-01-01

    Mechanical properties of low alloyed steels are directly determined by their microstructures. Thanks to versatility in their microstructures, the mechanical properties of low alloyed steels are much more adjustable than other materials. In the industry, one of the most effective ways to obtain the

  11. Microstructural characteristics and second-phase particles in yttrium-bearing Fe-10Ni-7Mn martensitic steels

    Institute of Scientific and Technical Information of China (English)

    F. Forghani; M. Nili-Ahmadabadi

    2014-01-01

    In this study, the microstructure and second-phase particles in yttrium (0.05 wt.%and 0.8 wt.%) bearing Fe-10Ni-7Mn steels were characterized. The results of X-ray analysis as well as scanning electron microscopy coupled with energy dispersive X-ray spectroscopy indicated the formation of (Fe, Ni, Mn)17Y2 precipitates with hexagonal structure in a Fe-10Ni-7Mn-0.8Y (wt.%) alloy. Lattice parameters of these precipitates were calculated as follows:a=0.8485 nm and c=0.8274 nm. Formation of Y2O3 sub-micron particles was also confirmed in both yttrium bearing steels via electrolytic phase extraction method. The effect of these precipitates on the prior austenite grain size was investigated. The results revealed that these precipitates had an effective role in controlling the prior austenite grain size.

  12. Evolution of magnetic phase at low aging temperature in a heavily cold-drawn stainless steel fiber

    Science.gov (United States)

    Yang, Shun-Tung; Hwang, Weng-Sing; Shyr, Tien-Wei; Cheng, I.-Lin

    2012-08-01

    The evolution of the magnetic phase upon aging at 300-520 °C in a heavily cold-drawn AISI 316L austenitic stainless steel fiber was studied using thermomagnetic analysis (TMA) and magnetic force microscopy with a heating stage. An increasing trend of magnetization from 50 °C to around 470 °C in the heating curves of TMA in austenitic stainless steels after a cold-drawing process was observed. No significant Ms temperature signal in the TMA curve at cooling indicated an increase in magnetization upon cooling period without significant phase transformation. A series of in situ magnetic force microscopy observations reveal a growth of the magnetic domain structure after aging at 300 °C for 2.5 h. Results show that the ferromagnetic increase during aging at lower annealing temperature resulted from the growth of martensite.

  13. DETERMINATION OF FORMABILITY PARAMETERS OF ERDEMİR 6114 SHEETS TEMPERED AT DUAL PHASE REGIONS

    Directory of Open Access Journals (Sweden)

    N. Sinan KÖKSAL

    2001-03-01

    Full Text Available Formability versus hardening process of ERDEMİR 6114 (SAE 1005 sheet was examined for determining the convenient tempering temperature providing optimum formability. Here, the effects of factors on formability; anisotropy factor (R, deformation hardening exponent (n, stretchability (h, yield point (Re and tensile strength (Rm variation were examined considering drawing direction also. Homogenous structures of test specimens were obtained by normalization tempering such as keeping in furnace at 890 0 C for 30 minutes and cooling in air. Tempering process of the samples were done at dual phase regions at temperatures 740, 770, 800, 820 and 850 0 C for 30 minutes and quenching in water afterwards. After tensile test and Erichsen experiment at room temperature, differences in yield point (Re , tensile strength (Rm, R, n and h values were observed. As a conclusion, it has been seen that R and n values of the samples tempered at 740 and 770 0 C were increased and h value were higher than the others, so formability characteristics of these samples were better than the other samples.

  14. Estimation of dual phase lag model parameters using the evolutionary algorithms

    Directory of Open Access Journals (Sweden)

    B. Mochnacki

    2011-07-01

    Full Text Available Generalization of Fourier law, in particular the introduction of two ‘delay times’ (relaxation time q and thermalization time T leads to thenew form of energy equation called the dual-phase-lag model (DPLM. This equation should be applied in a case of microscale heat transfermodeling. In particular, DPLM constitutes a good approximation of thermal processes which are characterized by extremely short duration(e.g. ultrafast laser pulse, extreme temperature gradients and geometrical features of domain considered (e.g. thin metal film. The aim ofconsiderations presented in this paper is the identification of two above mentioned positive constants q, T. They correspond to the relaxationtime, which is the mean time for electrons to change their energy states and the thermalization time, which is the mean time required forc(TTl G(TT electrons and lattice to reach equilibrium. In this paper the DPlLMlequation ise appllied for analysis of thermal processes proceeding in a thint metal film subjected to a laser beam. At the stage of computations connected with the identification problem solution the evolutionaryalgorithms are used. To solve the problem the additional information concerning the transient temperature distribution on a metal film surface is assumed to be known.

  15. Three-dimensional simulations of microstructural evolution in polycrystalline dual-phase materials with constant volume fractions

    DEFF Research Database (Denmark)

    Poulsen, Stefan Othmar; Voorhees, P.W.; Lauridsen, Erik Mejdal

    2013-01-01

    The microstructural evolution of a polycrystalline dual-phase material with a constant volume fraction of the phases was investigated using large-scale three-dimensional phase-field simulations. All materials parameters are taken to be isotropic, and microstructures with volume fractions of 50....../50 and 40/60 were examined. After an initial transient, the number of grains decrease from ∼2600 to ∼500. It was found that the mean grain size of grains of both phases obeyed a power law with an exponent of 3, and the microstructural evolution was found to be controlled by diffusion. Steady...... with the topology of single-phase grain structures as determined by experiment and simulation. The evolution of size and number of faces for the minority and majority phase grains in the 40/60 volume fraction simulation is presented and discussed. Non-constant curvature across some interphase boundaries...

  16. WA105: A large demonstrator of a liquid argon dual phase TPC

    Science.gov (United States)

    Zambelli, L.; Murphy, S.; WA105 Collaboration

    2017-09-01

    The Liquid argon technology has been chosen for the DUNE underground experiment for the study of neutrino oscillations, neutrino astrophysics and proton decay. This detector has excellent tracking and calorimetric capabilities much superior to currently operating neutrino detectors. WA105 is a large demonstrator of the dual-phase liquid argon TPC based on the GLACIER design, with a 6×6×6 m3 (appr. 300t) active volume. Its construction and operation test scalable solutions for the crucial aspects of this detector: ultra-high argon purity in non-evacuable tanks, long drifts, very high drift voltages, large area MPGD, cold preamplifiers. The TPC will be built inside a tank based on industrial LNG technology. Electrons produced in the liquid argon are extracted in the gas phase. Here, a readout plane based on Large Electron Multipliers (LEM’s) provides amplification before the charge collection onto an anode plane with strip readout. This highly cost effective solution provides excellent imaging capabilities with equal charge sharing on both views. PMTs located at the bottom of the tank containing the liquid argon provide the readout of the scintillation light. This demonstrator is an industrial prototype of the design proposed for a large underground detector. WA105 is under construction at CERN and will be exposed to a charged particle beam (0.5 - 20 GeV/c) in the North Area in 2018. The data will provide necessary calibration of the detector performances and benchmark sophisticated reconstruction algorithms. This project is a crucial milestone for the long baseline neutrino program DUNE.

  17. Investigating enhanced mechanical properties in dual-phase Fe-Ga-Tb alloys

    Science.gov (United States)

    Meng, Chongzheng; Wang, Hui; Wu, Yuye; Liu, Jinghua; Jiang, Chengbao

    2016-10-01

    Dual-phase (Fe83Ga17)100-xTbx alloys with 0 ≤ x ≤ 1 were synthesized by arc melting and homogenization treatment. The microstructures and the corresponding mechanical properties were systematically investigated. The chemical composition of the body centered cubic matrix is Fe83Ga17. The monoclinic second phase was composed of meltable precipitates with approximate composition Fe57Ga33Tb10. The nano-hardness of matrix and precipitates were 2.55 ± 0.17 GPa and 6.81 ± 1.03 GPa, respectively. Both the ultimate tensile strength (UTS) and fracture strain (ɛ) of the alloys were improved by the precipitates for x ≤ 0.2 alloys, but the strain decreases significantly at higher values of x. As potential structural-functional materials, the best mechanical properties obtained were a UTS of 595 ± 10 MPa and an ɛ of 3.5 ± 0.1%, four-fold and seven-fold improvements compared with the un-doped alloy. The mechanism for these anomalous changes of mechanical properties was attributed to the dispersed precipitates and semi-coherent interfaces, which serve as strong obstacles to dislocation motion and reduce the stress concentration at the grain boundaries. A sizeable improvement of magnetostriction induced by the precipitates in the range 0 ≤ x ≤ 0.2 was discovered and an optimal value of 150 ± 5 ppm is found, over three times higher than that of the un-doped alloy.

  18. Carbon diffusion and phase transformations during gas carburizing of high-alloyed stainless steels: Experimental study and theoretical modeling

    Science.gov (United States)

    Turpin, T.; Dulcy, J.; Gantois, M.

    2005-10-01

    Gas carburizing of high-alloyed stainless steels increases surface hardness, as well as the overall mechanical characteristics of the surface. The growth of chromium-rich carbides during carbon transfer into the steel causes precipitation hardening in the surface, but decreases the chromium content in solid solution. In order to maintain a good corrosion resistance in the carburized layer, the stainless steel composition and the carburizing process need to be optimized. To limit the experimental work, a methodology using software for modeling the thermodynamic and kinetic properties in order to simulate carbon diffusion and phase transformations during gas carburizing is presented. Thermodynamic calculations are initially used to find the optimum parameters ( T, carbon wt pct, etc.) in order to maintain the highest Cr and Mo contents in the austenitic solid solution. In a second step, kinetic calculations using the diffusion-controlled transformations (DICTRA) software are used to predict how the amount of the different phases varies and how the carbon profile in the steel changes as a function of time during the process. Experimental carbon profiles were determined using a wavelength-dispersive spectrometer for electron-probe microanalysis (WDS-EPMA), while carbide compositions were measured by energy-dispersive spectroscopy_X (EDS_X) analyses. A good agreement between calculated and experimental values was observed for the Fe-13Cr-5Co-3Ni-2Mo-0.07C and the Fe-12Cr-2Ni-2Mo-0.12C (wt pct) martensitic stainless steels at 955 °C and 980 °C.

  19. Nanostructure and Properties of Corrosion Resistance in C+Ti Multi-Ion-Implanted Steel

    Institute of Scientific and Technical Information of China (English)

    张通和; 吴瑜光; 刘安东; 张旭; 王晓妍

    2003-01-01

    The corrosion and pitting corrosion resistance of C+ Ti dual and C+Ti+C ternary implanted H13 steel were studied by using a multi-sweep cyclic voltammetry and a scanning electron microscope. The effects of phase formation on corrosion and pitting corrosion resistance were explored. The x-ray diffraction analysis shows that the nanometer-sized precipitate phases consist of compounds of Fe2 Ti, TiC, Fe2C and Fe3 C in dual implanted layer and even in ternary implanted layer. The passivation layer consists of these nanometer phases. It has been found that the corrosion and pitting corrosion resistance of dual and ternary implanted H13 steel are improved extremely. The corrosion resistance of ternary implanted layer is better than that of dual implantations and is enhanced with the increasing ion dose. When the ion dose of Ti is 6 × 1017/cm2 in the ternary implantation sample, the anodic peak current density is 95 times less than that of the H13 steel. The pitting corrosion potential of dual and ternary implantation samples is in the range from 55mV to 160mV which is much higher than that of the H13 steel. The phases against the corrosion and pitting corrosion are nanometer silkiness phases.

  20. Evolution of structural phase states of 08Cr18Ni10Ti steel subjected to high-cycle fatigue with electrostimulation

    Institute of Scientific and Technical Information of China (English)

    Molotova; K.Ye.; Konovalov; S.V.; Kozlov; E.V.; Ivanov; Yu.F.; Gromov; V.E.

    2005-01-01

    This work contains analysis results from the study of defective substructure and phase state of steel subjected to fatigue loading and pulse current action in order to increase its fatigue life.……

  1. Effect of alloying elements on the composition of carbide phases and mechanical properties of the matrix of high-carbon chromium-vanadium steel

    Science.gov (United States)

    Titov, V. I.; Tarasenko, L. V.; Utkina, A. N.

    2017-01-01

    Based on the results of phase physicochemical analysis of high-carbon chromium-vanadium steel, the predominant type of carbide that provides high wear resistance has been established, and its amount and amount of carbon in martensite have been determined. Data on the composition and the amount of carbide phase and on the chemical composition of the martensite of high-carbon steel have been obtained, which allows determination of the alloying-element concentration limits. The mechanical testing of heats of a chosen chemical composition has been carried out after quenching and low-temperature tempering. The tests have demonstrated benefits of new steel in wear resistance and bending strength with the fatigue strength being retained, compared to steels subjected to cementation. The mechanism of secondary strengthening of the steel upon high-temperature tempering has been revealed. High-temperature tempering can be applied to articles that are required to possess both high wear resistance and heat resistance.

  2. Ultrasonic study of adhesive bond quality at a steel-to-rubber interface by using quadrature phase detection techniques

    Science.gov (United States)

    Smith, A. C.; Yang, H.

    1989-01-01

    The quadrature phase detection technique was used to simultaneously monitor the phase and amplitude of a toneburst signal normally reflected from an adhesively bonded steel-to-rubber interface. The measured phase was found to show a positive shift for all bonded samples with respect to the disbonded state - the phase shift being larger for samples with weaker bonds, as manifested by smaller values of applied tensile loads at failure. A model calculation, which incorporates the concept of interfacial strength into the usual problem of wave propagation in multilayered media, was used to deduce a bond-quality parameter from an experimentally measured phase shift. This bond-quality parameter was found to be correlated with the tensile strength of the adhesive bonds at failure loads.

  3. An ultra-thin dual-band phase-gradient metasurface using hybrid resonant structures for backward RCS reduction

    Science.gov (United States)

    Cheng, Yongzhi; Wu, Chenjun; Ge, Chenchen; Yang, Jiaji; Pei, Xiaojun; Jia, Fan; Gong, Rongzhou

    2017-05-01

    We introduce and investigate, both experimentally and theoretically, a dual-band phase-gradient metasurface (PGM) to accurately facilitate dual-band beams deflection for electromagnetic waves. The designed PGM is composed of two kinds of split-ring resonators as the basic element of a super cell. These hybrid resonant structures can generate phase gradients at two distinct frequencies, which, in turn, generate appropriately artificial wave vectors that meet the requirements for anomalous reflection in terms of generalized Snell's law. Both simulations and experiments are consistent with the theoretical predictions. Further, this PGM can work at 8.9 and 11.4 GHz frequencies providing a phenomenon of anomalous reflection, which is useful for backward radar cross section reduction.

  4. Dual-Phase 99MTc-MIBI Parathyroid Imaging Reveals Synchronous Parathyroid Adenoma and Papillary Thyroid Carcinoma: A Case Report

    Directory of Open Access Journals (Sweden)

    Ming-Che Chang

    2008-10-01

    Full Text Available The possibility of a coincidental appearance of hyperparathyroidism and thyroid cancer is not often considered because of its low incidence. Here, we present a case of a 49-year-old woman with a parathyroid adenoma coexisting with two sites of papillary thyroid carcinoma. Dual-phase 99mTc-methoxyisobutylisonitrile (MIBI parathyroid imaging before the operation correctly visualized the site of the parathyroid adenoma. In addition, two papillary thyroid carcinomas showed faint uptake of 99mTc-MIBI on delayed image. Total thyroidectomy and parathyroidectomy of a solitary parathyroid adenoma were performed. The patient subsequently underwent radioiodine-131 ablation and was treated with T4 suppression. This case illustrates the need for clinical awareness of concomitant hyperparathyroidism and thyroid cancer. Dual-phase 99mTc-MIBI parathyroid imaging may be useful for detecting indolent thyroid cancer before it becomes a distinct disease.

  5. Suppression of Twinning and Phase Transformation in an Ultrafine Grained 2 GPa Strong Metastable Austenitic Steel: Experiment and Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yongfeng; Jia, Nan; Wang, Y. D.; Sun, Xin; Zuo, Liang; Raabe, Dierk

    2015-07-17

    An ultrafine-grained 304 austenitic 18 wt.%Cr-8 wt.%Ni stainless steel with a grain size of ~270 nm was synthesized by accumulative rolling (67 % total reduction) and annealing (550 °C, 150s). Uniaxial tensile testing at room temperature reveals an extremely high yield strength of 1890 ± 50MPa and a tensile strength of 2050 ± 30MPa, while the elongation reaches 6 ± 1%. Experimental characterization on samples with different grain sizes between 270 nm and 35 μm indicates that both, deformation twinning and martensitic phase transformation are significantly retarded with increasing grain refinement. A crystal plasticity finite element model incorporating a constitutive law reflecting the grain size-controlled dislocation slip and deformation twinning captures the micromechanical behavior of the steels with different grain sizes. Comparison of simulation and experiment shows that the deformation of ultrafine-grained 304 steels is dominated by the slip of partial dislocations, whereas for coarse-grained steels dislocation slip, twinning and martensite formation jointly contribute to the shape change.

  6. Effect of thermomechanical treatment modes on structural-phase states and mechanical properties of metastable austenitic steel

    Science.gov (United States)

    Akkuzin, S. A.; Litovchenko, I. Yu.; Polekhina, N. A.; Tyumentsev, A. N.

    2016-11-01

    The features of the structural-phase states and mechanical properties of metastable austenitic steel after thermomechanical treatments have been investigated. It is shown that low-temperature and subsequent deformation in the temperature range 300-773 K contributes to the direct (γ → α')-martensitic transformation. The combination of low-temperature, subsequent warm deformation at 873 K and annealing at 1073 K leads to the direct (γ → α')- and reverse (α' → γ)-martensitic transformations. As a result of thermomechanical treatments submicrocrystalline two-phase structural states with high strength properties (σ0.1 ≈ 1160-1350 MPa) are formed.

  7. Non-destructive detection of corrosion applied to steel and galvanized steel coated with organic paints by the pulsed phase thermography

    Energy Technology Data Exchange (ETDEWEB)

    Schoenberger, A.; Giese, V. [BMW AG, Munich (Germany); Virtanen, S. [Department of Materials Science, WW4-LKO, University of Erlangen-Nuremberg, Erlangen (Germany); Schroettner, H. [Centre for Electron Microscopy Graz (ZFE), Graz (Austria); Spiessberger, C. [Edevis GmbH, Stuttgart (Germany)

    2012-03-15

    Organic coatings in the automobile industry have to resist corrosion and mechanical damage from stone chipping. Currently, no tool is established in industrial non-destructive applications for analyzing the damage of stone-impacts and the following corrosion after accelerated corrosion tests. Measurement methods such as the scanning Kelvin probe can analyze the corrosion progress in a detailed manner, but with a long measurement time. The pulsed phase thermography (PPT) is a non-destructive tool to analyze inhomogeneities and defects in materials, with a huge field of applications existing. The present work shows advances in using the PPT to detect propagation of corrosion under coatings. Physical principles of the mechanism of the corrosion detection under coatings are described. Results of measurements of organic coatings on carbon steel as well as of organic coated galvanized steel show the corrosion propagation. Influencing factors to the measurement such as the thickness of the coatings are investigated, but no significant effect on the quality of the analysis was found. The corrosion progress can be monitored by the PPT fast and reliably. The achieved results correlate with the theoretical basis and the test results after surface characterization and destructive analysis of samples. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. A numerical study on dual-phase-lag model of bio-heat transfer during hyperthermia treatment.

    Science.gov (United States)

    Kumar, P; Kumar, Dinesh; Rai, K N

    2015-01-01

    The success of hyperthermia in the treatment of cancer depends on the precise prediction and control of temperature. It was absolutely a necessity for hyperthermia treatment planning to understand the temperature distribution within living biological tissues. In this paper, dual-phase-lag model of bio-heat transfer has been studied using Gaussian distribution source term under most generalized boundary condition during hyperthermia treatment. An approximate analytical solution of the present problem has been done by Finite element wavelet Galerkin method which uses Legendre wavelet as a basis function. Multi-resolution analysis of Legendre wavelet in the present case localizes small scale variations of solution and fast switching of functional bases. The whole analysis is presented in dimensionless form. The dual-phase-lag model of bio-heat transfer has compared with Pennes and Thermal wave model of bio-heat transfer and it has been found that large differences in the temperature at the hyperthermia position and time to achieve the hyperthermia temperature exist, when we increase the value of τT. Particular cases when surface subjected to boundary condition of 1st, 2nd and 3rd kind are discussed in detail. The use of dual-phase-lag model of bio-heat transfer and finite element wavelet Galerkin method as a solution method helps in precise prediction of temperature. Gaussian distribution source term helps in control of temperature during hyperthermia treatment. So, it makes this study more useful for clinical applications.

  9. Industrial application of liquid steel filtration out of dispersed nonmetallic phase in the continuous casting machine

    Directory of Open Access Journals (Sweden)

    K. Janiszewski

    2013-01-01

    Full Text Available Hitherto existing investigations concerning the ceramic filter use in the steel making processes (both of laboratory and industrial scale have given good results. The obtained results of filtration (in the laboratory have proved that this method may be used as an effective and cheap way of steel filtration from non-metallic inclusions. Placing filters in the tundish is the best location in consideration of limiting the possibility of secondary pollution of steel. Yet, the results presented in this paper, of an experiment prepared and carried out in the industrial environment, are the only positive results obtained, which are connected with so much quantities of liquid steel processed with use of the multi-hole ceramic filters.

  10. Silicon photonic integrated circuit swept-source optical coherence tomography receiver with dual polarization, dual balanced, in-phase and quadrature detection.

    Science.gov (United States)

    Wang, Zhao; Lee, Hsiang-Chieh; Vermeulen, Diedrik; Chen, Long; Nielsen, Torben; Park, Seo Yeon; Ghaemi, Allan; Swanson, Eric; Doerr, Chris; Fujimoto, James

    2015-07-01

    Optical coherence tomography (OCT) is a widely used three-dimensional (3D) optical imaging method with many biomedical and non-medical applications. Miniaturization, cost reduction, and increased functionality of OCT systems will be critical for future emerging clinical applications. We present a silicon photonic integrated circuit swept-source OCT (SS-OCT) coherent receiver with dual polarization, dual balanced, in-phase and quadrature (IQ) detection. We demonstrate multiple functional capabilities of IQ polarization resolved detection including: complex-conjugate suppressed full-range OCT, polarization diversity detection, and polarization-sensitive OCT. To our knowledge, this is the first demonstration of a silicon photonic integrated receiver for OCT. The integrated coherent receiver provides a miniaturized, low-cost solution for SS-OCT, and is also a key step towards a fully integrated high speed SS-OCT system with good performance and multi-functional capabilities. With further performance improvement and cost reduction, photonic integrated technology promises to greatly increase penetration of OCT systems in existing applications and enable new applications.

  11. A new method of time difference measurement: The time difference method by dual phase coincidence points detection

    Science.gov (United States)

    Zhou, Wei

    1993-01-01

    In the high accurate measurement of periodic signals, the greatest common factor frequency and its characteristics have special functions. A method of time difference measurement - the time difference method by dual 'phase coincidence points' detection is described. This method utilizes the characteristics of the greatest common factor frequency to measure time or phase difference between periodic signals. It can suit a very wide frequency range. Measurement precision and potential accuracy of several picoseconds were demonstrated with this new method. The instrument based on this method is very simple, and the demand for the common oscillator is low. This method and instrument can be used widely.

  12. Thermal Behavior of an HSLA Steel and the Impact in Phase Transformation: Submerged Arc Welding (SAW) Process Approach to Pipelines

    Science.gov (United States)

    Costa, P. S.; Reyes-Valdés, F. A.; Saldaña-Garcés, R.; Delgado, E. R.; Salinas-Rodríguez, A.

    Heat input during welding metal fusion generates different transformations, such as grain growth, hydrogen cracking, and the formation of brittle structures, generally associated with the heat-affected zone (HAZ). For this reason, it is very important to know the behavior of this area before welding. This paper presents a study of the thermal behavior and its effect on phase transformations in the HAZ, depending on cooling rates (0.1-200 °C/s) to obtain continuous cooling transformation (CCT) curves for an high-strength low-alloy (HSLA) steel. In order to determine the formed phases, optical microscopy and Vickers microhardness measurement were used. The experimental CCT curve was obtained from an HSLA steel, and the results showed that, with the used cooling conditions, the steel did not provide formation of brittle structures. Therefore, it is unlikely that welds made by submerged arc welding (SAW) may lead to hydrogen embrittlement in the HAZ, which is one of the biggest problems of cracking in gas conduction pipelines. In addition, with these results, it will be possible to control the microstructure to optimize the pipe fabrication with SAW process in industrial plants.

  13. Global and local deformation behavior and mechanical properties of individual phases in a quenched and partitioned steel

    Energy Technology Data Exchange (ETDEWEB)

    Diego-Calderón, I. de, E-mail: irenedediego.calderon@imdea.org [IMDEA Materials Institute, Calle Eric Kandel 2, Getafe 28906, Madrid (Spain); De Knijf, D. [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, B-9052 Zwijnaarde (Ghent) (Belgium); Monclús, M.A.; Molina-Aldareguia, J.M.; Sabirov, I. [IMDEA Materials Institute, Calle Eric Kandel 2, Getafe 28906, Madrid (Spain); Föjer, C. [ArcelorMittal Global R& D Gent, Pres. J. F. Kennedylaan 3, B-9060 Zelzate (Belgium); Petrov, R.H. [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, B-9052 Zwijnaarde (Ghent) (Belgium); Department of Materials Science and Engineering, Delft University of Technology, 2628 CD Delft (Netherlands)

    2015-04-10

    Third generation advanced high strength steels produced via quenching and partitioning (Q&P) treatment are receiving increased attention. A 0.25C–3Mn–1.5Si–0.023 Al steel was subjected to Q&P processing (with varying partitioning temperature and time) resulting in the formation of complex multi-phase microstructures. The effect of Q&P parameters on the microstructure and morphology of microconstituents was analyzed. Mechanical properties of the material and of its individual microconstituents were studied via tensile testing and nanoindentation on individual microconstituents, which were identified a priori by electron back-scattered diffraction analysis. Special attention is paid to the effect of the morphology of retained austenite on its transformation stability. In situ tensile tests and digital image correlation analysis were performed to study deformation behavior of the Q&P processed steel at the micro-scale with respect to the local microstructure. The effect of local microstructure and properties of individual phases on the degree of strain partitioning is discussed.

  14. Synthesis of steel slag ceramics:chemical composition and crystalline phases of raw materials

    Institute of Scientific and Technical Information of China (English)

    Li-hua Zhao; Wei Wei; Hao Bai; Xu Zhang; Da-qiang Cang

    2015-01-01

    Two types of porcelain tiles with steel slag as the main raw material (steel slag ceramics) were synthesized based on the CaO–Al2O3–SiO2 and CaO–MgO–SiO2 systems, and their bending strengths up to 53.47 MPa and 99.84 MPa, respectively, were obtained. The presence of anorthite,α-quartz, magnetite, and pyroxene crystals (augite and diopside) in the steel slag ceramics were very different from the composition of traditional ceramics. X-ray diffraction (XRD) and electron probe X-ray microanalysis (EPMA) results illustrated that the addition of steel slag reduced the temperature of extensive liquid generation and further decreased the firing temperature. The considerable contents of glass-modifying oxide liquids with rather low viscosities at high temperature in the steel slag ceramic adobes promoted element diffusion and crystallization. The results of this study demonstrated a new approach for extensive and effective recycling of steel slag.

  15. Surface modification of stainless steel by plasma-based fluorine and silver dual ion implantation and deposition.

    Science.gov (United States)

    Shinonaga, Yukari; Arita, Kenji

    2009-11-01

    The aims of this study were to modify dental device surface with fluorine and silver and to examine the effectiveness of this new surface modification method. Stainless steel plates were modified by plasma-based fluorine and silver ion implantation-deposition method. The surface characteristics and brushing abrasion resistance were evaluated by XPS, contact angle and brushing abrasion test. XPS spectra of modified specimens showed the peaks of fluoride and silver. These peaks were detected even after brushing abrasion test. Water contact angle significantly increased due to implantation-deposition of both fluorine and silver ions. Moreover, the contact angle of the modified specimen was significantly higher than that of fluorine only deposited specimen with the same number of brushing strokes. This study indicates that this new surface modification method of fluorine and silver ion implantation-deposition improved the brushing abrasion resistance and hydrophobic property making it a potential antimicrobial device.

  16. Improvement of extraction capability of magnetic molecularly imprinted polymer beads in aqueous media via dual-phase solvent system.

    Science.gov (United States)

    Hu, Yuling; Liu, Ruijin; Zhang, Yi; Li, Gongke

    2009-08-15

    In this study, a novel and simple dual-phase solvent system for the improvement of extraction capability of magnetic molecularly imprinted polymer (MIP) beads in aqueous sample was proposed. The method integrated MIP extraction and micro-liquid-liquid extraction (micro-LLE) into only one step. A magnetic MIP beads using atrazine as template was synthesized, and was applied to aqueous media by adding micro-volume of n-hexane to form a co-extraction system. The magnetic MIP beads preferred to suspend in the organic phase, which shielded them from the disturbance of water molecule. The target analytes in the water sample was extracted into the organic phase by micro-LLE and then further bound to the solid-phase of magnetic MIP beads. The beads specificity was significantly improved with the imprinting efficiency of template increasing from 0.5 to 4.4, as compared with that in pure aqueous media. The extraction capacity, equilibration process and cross-selectivity of the MIP dual-phase solvent extraction system were investigated. The proposed method coupled with high-performance liquid chromatography was applied to the analysis of atrazine, simazine, propazine, simetryn, prometryne, ametryn and terbutryn in complicated sample such as tomato, strawberry juice and milk. The method is selective, sensitive and low organic solvent-consuming, and has potential to broaden the range of MIP application in biological and environmental sample.

  17. Narrow gap TIG and electron beam weld inspection in austenitic stainless steel using pulse echo, TOFD and phased array ultrasonics

    Energy Technology Data Exchange (ETDEWEB)

    Quirk, K.P.; Turner, J.L. [Phoenix Inspection Systems Limited, Warrington (United Kingdom)

    2004-07-01

    'Full-text:' Narrow gap Tungsten Inert Gas (TIG) and Electron Beam (EB) welding techniques are being considered for the splice joint welds on the austenitic stainless steel Vacuum Vessel in the next generation of experimental Fusion Power stations under the ITER programme. Under the programme there is a requirement to develop automated ultrasonic NDT techniques to inspect material up to 60 mm thick in both weld types. These narrow welds are difficult to inspect because of the steep fusion faces made more difficult in this project by the beam scattering effects of austenitic stainless steel welds and the very limited access from only one side of the vessel. The paper details the development of the combined Pulse Echo, TOFD and Phased Array techniques on behalf of ITER. The authors describe the philosophy behind the inspections, results and possible transfer of the technology to other sectors of industry. (author)

  18. Automated Flaw Detection Scheme For Cast Austenitic Stainless Steel Weld Specimens Using Hilbert Huang Transform Of Ultrasonic Phased Array Data

    Energy Technology Data Exchange (ETDEWEB)

    Khan, T.; Majumdar, Shantanu; Udpa, L.; Ramuhalli, Pradeep; Crawford, Susan L.; Diaz, Aaron A.; Anderson, Michael T.

    2012-01-01

    The objective of this work is to develop processing algorithms to detect and localize the flaws using NDE ultrasonic data. Data was collected using cast austenitic stainless steel (CASS) weld specimens on-loan from the U.S. nuclear power industry’s Pressurized Water Reactor Owners Group (PWROG) specimen set. Each specimen consists of a centrifugally cast stainless steel (CCSS) pipe section welded to a statically cast (SCSS) or wrought (WRSS) section. The paper presents a novel automated flaw detection and localization scheme using low frequency ultrasonic phased array inspection signals in the weld and heat affected zone of the base materials. The major steps of the overall scheme are preprocessing and region of interest (ROI) detection followed by the Hilbert Huang transform (HHT) of A-scans in the detected ROIs. HHT offers time-frequency-energy distribution for each ROI. The accumulation of energy in a particular frequency band is used as a classification feature for the particular ROI.

  19. One-pot solvothermal synthesis of dual-phase titanate/titania Nanoparticles and their adsorption and photocatalytic Performances

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Yu Hua; Gong, Dangguo; Tang, Yuxin; Ho, Jeffery Weng Chye; Tay, Yee Yan; Lau, Wei Siew; Wijaya, Olivia; Lim, Jiexiang; Chen, Zhong, E-mail: aszchen@ntu.edu.sg

    2014-06-01

    Dual phase titanate/titania nanoparticles undergo phase transformation gradually with the increase of solvothermal synthesis temperature from 100 °C to 200 °C, and eventually are fully transformed into anatase TiO{sub 2}. The crystal structure change results in the changes of optical absorption, sensitizer/dopant formation and surface area of the materials which finally affect the overall dye removal ability. Reactions under dark and light have been conducted to distinguish the contributions of surface adsorption from photocatalytic degradation. The sample synthesized at 160 °C (S160) shows the best performances for both adsorption under dark and photocatalytic degradation of methylene blue (MB) under visible light irradiation. The adsorption mechanism for S160 is determined as monolayer adsorption based on the adsorption isotherm test under dark condition, and an impressive adsorption capacity of 162.19 mg/g is achieved. For the photocatalytic application, this sample at 0.1 g/L loading is also able to degrade 20 ppm MB within 6 hours under the visible light (>420 nm) condition. - Graphical abstract: The effect of solvothermal synthesis temperature on the formation and dye removal performance of dual phase titanate/titania nanoparticles was unveiled and optimized. - Highlights: • Low temperature one-pot solvothermal synthesis of dual-phase photocatalysts. • Correlation of the synthesis temperature is made with the phase composition. • Adsorption isotherm, kinetics, photocatalytic degradation were studied. • Synthesis at 160 °C yields the best material for adsorption of MB in dark. • The same sample also shows the best visible light degradation of MB.

  20. Investigations on the growth kinetics of Laves phase precipitates in 12% Cr creep-resistant steels: Experimental and DICTRA calculations

    Energy Technology Data Exchange (ETDEWEB)

    Prat, O. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Strasse 1, 40237 Duesseldorf (Germany)] [Universidad de Concepcion, Departamento de Ingenieria de Materiales, Edmundo Larenas 270, Concepcion (Chile); Garcia, J., E-mail: jose.garcia@helmholtz-berlin.de [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Rojas, D. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Strasse 1, 40237 Duesseldorf (Germany); Carrasco, C. [Universidad de Concepcion, Departamento de Ingenieria de Materiales, Edmundo Larenas 270, Concepcion (Chile); Inden, G. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Strasse 1, 40237 Duesseldorf (Germany)

    2010-10-15

    The growth kinetics of Laves phase precipitates (type Fe{sub 2}W) in the early stage of creep (650 deg. C for 10,000 h) in two 12% Cr ferrite-martensitic steels has been investigated. In one alloy the Laves phase formed on tempering, while in the second alloy the Laves phase precipitated during creep. Kinetic simulations were performed using the software DICTRA. The particle size of the Laves phase was measured on transmission electron microscopy samples. The equilibrium phase fraction of the Laves phase was reached in the first thousand hours. Simulations of particle growth showed good agreement with the experimental results. Competitive growth between M{sub 23}C{sub 6} and the Laves phase showed that M{sub 23}C{sub 6} carbides reached their equilibrium after 12 days, whereas the Laves phase reached equilibrium after 3 months. Simulations of the influence of the interfacial energy and addition of Co, Cu and Si on Laves phase precipitation are presented.

  1. Modelling and characterization of chi-phase grain boundary precipitation during aging of Fe-Cr-Ni-Mo stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Xu, W. [Netherlands Institute for Metals Research, Mekelweg 2, 2628 CD Delft (Netherlands)], E-mail: w.xu@nimr.nl; San Martin, D.; Rivera Diaz del Castillo, P.E.J.; Zwaag, S. van der [Fundamentals of Advanced Materials Group, Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS Delft (Netherlands)

    2007-10-15

    High molybdenum stainless steels may contain the chi-phase precipitate ({chi}, Fe{sub 36}Cr{sub 12}Mo{sub 10}) which may lead to undesirable effects on strength, toughness and corrosion resistance. In the present work, specimens of a 12Cr-9Ni-4Mo wt% steel are heat treated at different temperatures and times, and the average particle size and particle size distribution of chi-phase precipitate are studied quantitatively. A computer model based on the KWN framework has been developed to describe the evolution of chi-phase precipitation. The kinetic model takes advantage of the KWN model to describe the precipitate particle size distribution, and is coupled with the thermodynamic software ThermoCalc for calculating the instantaneous local thermodynamic equilibrium condition at the interface and the driving force for nucleation. A modified version of Zener's theory accounting for capillarity effects at early growth stages is implemented in this model. The prediction of the model for chi-phase precipitation at a grain boundary is compared to experimental results and both the average particle size and the particle size distribution are found to be in good agreement with experimental observations at late precipitation stages.

  2. Electric-field control of tri-state phase transformation with a selective dual-ion switch

    Science.gov (United States)

    Lu, Nianpeng; Zhang, Pengfei; Zhang, Qinghua; Qiao, Ruimin; He, Qing; Li, Hao-Bo; Wang, Yujia; Guo, Jingwen; Zhang, Ding; Duan, Zheng; Li, Zhuolu; Wang, Meng; Yang, Shuzhen; Yan, Mingzhe; Arenholz, Elke; Zhou, Shuyun; Yang, Wanli; Gu, Lin; Nan, Ce-Wen; Wu, Jian; Tokura, Yoshinori; Yu, Pu

    2017-06-01

    Materials can be transformed from one crystalline phase to another by using an electric field to control ion transfer, in a process that can be harnessed in applications such as batteries, smart windows and fuel cells. Increasing the number of transferrable ion species and of accessible crystalline phases could in principle greatly enrich material functionality. However, studies have so far focused mainly on the evolution and control of single ionic species (for example, oxygen, hydrogen or lithium ions). Here we describe the reversible and non-volatile electric-field control of dual-ion (oxygen and hydrogen) phase transformations, with associated electrochromic and magnetoelectric effects. We show that controlling the insertion and extraction of oxygen and hydrogen ions independently of each other can direct reversible phase transformations among three different material phases: the perovskite SrCoO3-δ (ref. 12), the brownmillerite SrCoO2.5 (ref. 13), and a hitherto-unexplored phase, HSrCoO2.5. By analysing the distinct optical absorption properties of these phases, we demonstrate selective manipulation of spectral transparency in the visible-light and infrared regions, revealing a dual-band electrochromic effect that could see application in smart windows. Moreover, the starkly different magnetic and electric properties of the three phases—HSrCoO2.5 is a weakly ferromagnetic insulator, SrCoO3-δ is a ferromagnetic metal, and SrCoO2.5 is an antiferromagnetic insulator—enable an unusual form of magnetoelectric coupling, allowing electric-field control of three different magnetic ground states. These findings open up opportunities for the electric-field control of multistate phase transformations with rich functionalities.

  3. Calibration of mass spectrometric measurements of gas phase reactions on steel surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Falk, H., E-mail: heinzfalk@unitybox.de [Scientific Consultancy, Kleve (Germany); Falk, M. [Falk Steuerungssysteme GmbH, Stadthagen (Germany); Wuttke, T. [FuE-EV ThyssenKrupp Steel Europe, Dortmund (Germany)

    2015-03-01

    The sampling of the surface-near gas composition using a mass spectrometer (MS-Probe) is a valuable tool within a hot dip process simulator. Since reference samples with well characterized surface coverage are usually not available, steel samples can deliver quantifiable amounts of the process relevant species H{sub 2}O, CO and H{sub 2} using the decarburization reaction with water vapor. Such “artificial calibration samples” (ACS) can be used for the calibration of the MS-Probe measurements. The carbon release rate, which is governed by the diffusion law, was determined by GDOES, since the diffusion coefficients of carbon in steel samples are usually not known. The measured carbon concentration profiles in the ACS after the thermal treatment confirmed the validity of the diffusion model described in this paper. The carbon bulk concentration > 100 ppm is sufficient for the use of a steel material as ACS. The experimental results reported in this paper reveal, that with the MS-Probe the LOQ of less than one monolayer of iron oxide can be achieved. - Highlights: • Gas to surface reactions at steel sheets is monitored with a mass spectrometer on-line. • The experimental data are calibrated in absolute terms as oxide mass densities. • Standard steel samples can be used for the calibration procedure. • Additional GDOES analysis of the carbon depletion in the calibration samples was carried out. • Limits of quantitation below one monolayer of oxide surface coverage were achieved.

  4. Dynamic reverse phase transformation induced high-strain-rate superplasticity in low carbon low alloy steels with commercial potential.

    Science.gov (United States)

    Cao, Wenquan; Huang, Chongxiang; Wang, Chang; Dong, Han; Weng, Yuqing

    2017-08-23

    Superplastic materials are capable of exhibiting large tensile elongation at elevated temperature, which is of great industrial significance because it forms the basis of a fabrication method to produce complex shapes. Superplasticity with elongation larger than 500% has been widely realized in many metals and alloys, but seldomly been succeeded in low carbon low alloy steel, even though it is commercially applied in the largest quantity. Here we report ultrahigh superplastic elongation of 900-1200% in the FeMnAl low carbon steels at high strain rate of 10(-2)-10(-3) s(-1). Such high-strain-rate superplasticity was attributed to dynamic austenite reverse phase transformation from a heavily cold rolled ferrite to fine-grained ferrite/austenite duplex microstructure and subsequent limited dynamic grain coarsening, under which a large fraction of high angle boundaries can be resulted for superplastic deformation. It is believed that this finding of the low carbon low alloy steel with ultrahigh superplasticity and relative low cost would remarkably promote the application of superplastic forming technique in automobile, aeronautical, astronautical and other fields.

  5. Influence of the Heterogeneous Nucleation Sites on the Kinetics of Intermetallic Phase Formation in Aged Duplex Stainless Steel

    Science.gov (United States)

    Melo, Elis Almeida; Magnabosco, Rodrigo

    2017-09-01

    The aim of this work is to study the influence of the heterogeneous nucleation site quantity, observed in different ferrite and austenite grain size samples, on the phase transformations that result in intermetallic phases in a UNS S31803 duplex stainless steel (DSS). Solution treatment was conducted for 1, 24, 96, or 192 hours at 1373 K (1100 °C) to obtain different ferrite and austenite grain sizes. After solution treatment, isothermal aging treatments for 5, 8, 10, 20, 30, or 60 minutes at 1123 K (850 °C) were performed to verify the influence of different amounts of heterogeneous nucleation sites in the kinetics of intermetallic phase formation. The sample solution treated for 1 hour, with the highest surface area between matrix phases, was the one that presented, after 60 minutes at 1123 K (850 °C), the smaller volume fraction of ferrite (indicative of greater intermetallic phase formation), higher volume of sigma (that was present in coral-like and compact morphologies), and chi phase. It was not possible to identify which was the first nucleated phase, sigma or chi. It was also observed that the phase formation kinetics is higher for the sample solution treated for 1 hour. It was evidenced that, from a certain moment on, the chi phase begins to be consumed due to the sigma phase formation, and the austenite/ferrite interface presents higher S V for all solution treatment times. It was also observed that intermetallic phases form preferably in austenite-ferrite interfaces, although the higher occupation rate occurs at triple junction ferrite-ferrite-ferrite. It was verified that there was no saturation of nucleation sites in any interface type nor triple junction, and the equilibrium after 1 hour of aging at 1123 K (850 °C) was not achieved. It was then concluded that sigma phase formation is possibly controlled by diffusional processes, without saturation of nucleation sites.

  6. High-Temperature Phase Equilibria of Duplex Stainless Steels Assessed with a Novel In-Situ Neutron Scattering Approach

    Science.gov (United States)

    Pettersson, Niklas; Wessman, Sten; Hertzman, Staffan; Studer, Andrew

    2017-01-01

    Duplex stainless steels are designed to solidify with ferrite as the parent phase, with subsequent austenite formation occurring in the solid state, implying that, thermodynamically, a fully ferritic range should exist at high temperatures. However, computational thermodynamic tools appear currently to overestimate the austenite stability of these systems, and contradictory data exist in the literature. In the present work, the high-temperature phase equilibria of four commercial duplex stainless steel grades, denoted 2304, 2101, 2507, and 3207, with varying alloying levels were assessed by measurements of the austenite-to-ferrite transformation at temperatures approaching 1673 K (1400 °C) using a novel in-situ neutron scattering approach. All grades became fully ferritic at some point during progressive heating. Higher austenite dissolution temperatures were measured for the higher alloyed grades, and for 3207, the temperature range for a single-phase ferritic structure approached zero. The influence of temperatures in the region of austenite dissolution was further evaluated by microstructural characterization using electron backscattered diffraction of isothermally heat-treated and quenched samples. The new experimental data are compared to thermodynamic calculations, and the precision of databases is discussed.

  7. Dual cure low-VOC coating process. Final technical report, Phase 3

    Energy Technology Data Exchange (ETDEWEB)

    Kinzer, K.E.

    1993-12-01

    US EPA is implementing increasingly stringent environmental regulations on the emissions of volatile organic compounds (VOCs), which amount to about 7 {times} 10{sup 9} lb/year, largely from paints and other coating systems in industry. Objective of this project is to develop Dual Cure Photocatalyst coating technology for aerospace topcoats (urethane/acrylate), aerospace primers (epoxy/acrylate), and solventless tape backings. Some problems (moisture etc.) were encountered in the primer area. Cost, economic, and energy analyses were conducted. The dual cure technology has already been commercialized in 3M`s flexible diamond resin products. Tabs.

  8. FLOW PATTERN AND PRESSURE LOSS OF OIL-WATER TWO-PHASE FLOW IN HORIZONTAL STEEL PIPE

    Institute of Scientific and Technical Information of China (English)

    CHEN Jie; YAN Da-fan; ZHAO Jing-mei; AN Wei-jie; YAN Da-chun

    2005-01-01

    Experimental Study on oil-water two-phase flow patterns and pressure loss was conducted on a horizontal steel pipe loop with 26.1mm inner diameter and 30m total length.The working fluids are white oil, diesel oil and tap water.Several instruments, including a new type of liquid-probe are successfully integrated to identify 7 different flow patterns.The characteristics of the flow patterns and the transition process were observed and depicted in this paper.Investigation revealed that the pressure loss was mainly depended on the flow patterns.

  9. Long-term creep strength degradation in T122/P122 steels for USC power plants

    Energy Technology Data Exchange (ETDEWEB)

    Igarashi, M.; Yoshizawa, M. [Corporate Research and Development Laboratories, Hyogo (Japan); Iseda, A. [Tubular Products Technology Department, Tokyo (Japan); Matsuo, H.; Kan, T. [Quality Control and Technical Service Department, Hyogo (Japan)

    2006-07-01

    Creep rupture and deformation behavior of KA-SUS410J3 type steels (equivalent to ASME P122/T122) with different Cr content and the resultant matrix phases such as {alpha}' (martensite) and {alpha}'+ {delta} (martensite and deltaferrite) has been studied using creep testing and a detailed TEM observation. New allowable tensile stress values of the steels with two different Cr content levels set using the region splitting method in Japan are tabulated. Long-term creep rupture strength, in particular, of the {alpha}'+ {delta} dual phase steel is found to be lower than that expected from the short-term creep testing. Fine grain microstructure is found to enhance the creep deformation at lower stress region and decrease in fine MX and unequal distribution of MX in the ferrite matrix are to be the major causes of the strength degradation in the {alpha}'+ {delta} dual phase steel with the higher Cr content. It is concluded that the heterogeneous creep deformation is much more pronounced at lower stress level in the dual phase steel, which is due to inhomogeneous microstructure consisting of {alpha}'+{delta} phase matrix and the relevant heterogeneous distribution of fine precipitates such as MX and M{sub 23}C{sub 6} in the {delta} ferrite matrix and near the interface between the soft {delta} ferrite and the hard martensite ({alpha}') phases. Homogeneous microstructure is a key for achieving the long-term creep strength in the advanced ferritic steels at elevated temperatures over 600 C. KA-SUS410J2TB steel (designated as HCM12) is found to exhibit a similar creep strength degradation, which is mainly due to a similar microstructure of KA-SUS410J3 type steel with the higher Cr content. (orig.)

  10. Diverse acidogenic effluents as feedstock for microalgae cultivation: Dual phase metabolic transition on biomass growth and lipid synthesis.

    Science.gov (United States)

    Chiranjeevi, P; Venkata Mohan, S

    2017-10-01

    In this study, a biorefinery process integrating dark fermentation with microalgae cultivation (dual phase metabolic transition) was demonstrated with real-field wastewater. Acid rich fermented effluents (distillery waste (FDW1); dairy waste (FDW2)) were used as feedstock for microalgae cultivation. Experiments were performed with FDW1 during growth phase (GP) in mixotrophic mode and FDW2 during stress phase (SP) in both mixotrophic and heterotrophic modes. Mixotrophic cultivation with FDW1 documented significantly higher biomass productivity (5.3g/l). Total lipid (TL) percentage was high in mixotrophic (34%) mode and neutral lipid (NL) was high in heterotrophic (13%) mode of cultivation during SP with FDW2. Overall, the microalgae growth is favoured with effluents containing high acetate, and low butyrate concentrations. Mixotrophic cultivation enhanced both biomass growth and lipid production along with simultaneous treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. In situ TEM study of G-phase precipitates under heavy ion irradiation in CF8 cast austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wei-Ying [Argonne National Laboratory, Argonne, IL 60439 (United States); University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Li, Meimei; Zhang, Xuan; Kirk, Marquis A.; Baldo, Peter M. [Argonne National Laboratory, Argonne, IL 60439 (United States); Lian, Tiangan [Electric Power Research Institute, Palo Alto, CA 94304 (United States)

    2015-09-15

    Thermally-aged cast austenitic stainless steels (CASS) CF8 was irradiated with 1 MeV Kr ions at 300, 350 and 400 °C to 1.88 × 10{sup 19} ions/m{sup 2} (∼3 dpa) at the IVEM-Tandem Facility at the Argonne National Laboratory. Before irradiation, the distribution of G-phase precipitates in the ferrite showed spatial variations, and both their size and density were affected by the ferrite–austenite phase boundary and presence of M{sub 23}C{sub 6} carbides. Under 300 °C irradiation, in situ TEM observation showed G-phase precipitates were relatively unchanged in the vicinity of the phase boundary M{sub 23}C{sub 6} carbides, while the density of G-phase precipitates increased with increasing dose within the ferrite matrix. Coarsening of G-phase precipitates was observed in the vicinity of phase boundary M{sub 23}C{sub 6} carbides at 350 °C and 400 °C.

  12. Modeling precipitation thermodynamics and kinetics in type 316 austenitic stainless steels with varying composition as an initial step toward predicting phase stability during irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Jae-Hyeok, E-mail: jhshim@kist.re.kr [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Povoden-Karadeniz, Erwin [Christian Doppler Laboratory for Early Stages of Precipitation, Vienna University of Technology, A-1040 Vienna (Austria); Kozeschnik, Ernst [Institute of Materials Science and Technology, Vienna University of Technology, A-1040 Vienna (Austria); Wirth, Brian D. [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States)

    2015-07-15

    Highlights: • We model the precipitation kinetics in irradiated 316 austenitic stainless steels. • Radiation-induced phases are predicted to form at over 10 dpa segregation conditions. • The Si content is the most critical for the formation of radiation-induced phases. - Abstract: The long-term evolution of precipitates in type 316 austenitic stainless steels at 400 °C has been simulated using a numerical model based on classical nucleation theory and the thermodynamic extremum principle. Particular attention has been paid to the precipitation of radiation-induced phases such as γ′ and G phases. In addition to the original compositions, the compositions for radiation-induced segregation at a dose level of 5, 10 or 20 dpa have been used in the simulation. In a 316 austenitic stainless steel, γ′ appears as the main precipitate with a small amount of G phase forming at 10 and 20 dpa. On the other hand, G phase becomes relatively dominant over γ′ at the same dose levels in a Ti-stabilized 316 austenitic stainless steel, which tends to suppress the formation of γ′. Among the segregated alloying elements, the concentration of Si seems to be the most critical for the formation of radiation-induced phases. An increase in dislocation density as well as increased diffusivity of Mn and Si significantly enhances the precipitation kinetics of the radiation-induced phases within this model.

  13. The WA105-3x1x1 m3 dual phase LAr-TPC demonstrator

    CERN Document Server

    Murphy, Sebastien

    2016-11-15

    The dual phase Liquid Argon Time Projection Chamber (LAr TPC) is the state-of-art technology for neutrino detection thanks to its superb 3D tracking and calorimetry performance. Its main feature is the charge amplification in gas argon which provides excellent signal-to-noise ratio. Electrons produced in the liquid argon are extracted in the gas phase. Here, a readout plane based on Large Electron Multiplier detectors provides amplification of the charges before its collection onto an anode with strip readout. The charge amplification enables constructing fully homoge- nous giant LAr-TPCs with tuneable gain, excellent charge imaging performance and increased sensitivity to low energy events. Following a staged approach the WA105 collaboration is con- structing a dual phase LAr-TPC with an active volume of 3x1x1m3 that will soon be tested with cosmic rays. Its construction and operation aims to test scalable solutions for the crucial aspects of this technology: ultra high argon purity in non-evacuable tank, la...

  14. Direct Torque Control with Full Order Stator Flux Observer for Dual-Three Phase Induction Motor Drives

    Science.gov (United States)

    Farina, Francesco; Bojoi, Radu; Tenconi, Alberto; Profumo, Francesco

    A Direct Torque Control (DTC) strategy for dual-three phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees with isolated neutral points. The proposed control strategy is based on Proportional Integral (PI) regulators implemented in the stator flux synchronous reference frame. To improve the flux estimation, an Adaptive Stator Flux Observer (ASFO) has been used. Doing so, besides a better flux estimation in contrast to open-loop flux estimators, it is possible to use the observed currents to compensate the inverter non-linear behavior (such as dead-time effects), improving the drive performance at low speed. This is particularly important for low voltage/high current applications, as the drive considered in this paper. The advantages of the discussed control strategy are: constant inverter switching frequency, good transient and steady-state performance and less distorted machine currents in contrast to DTC schemes with variable switching frequency. Experimental results are presented for a 10kW dual three-phase induction motor drive prototype.

  15. Prediction of solidification and phase transformation in weld metals for welding of high performance stainless steels; Kotaishoku kotainetsu stainless koyo yosetsu kinzoku no gyoko hentai no yosoku gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Koseki, T.; Inoue, H.; Morimoto, H.; Okita, S. [Nippon Steel Corp., Tokyo (Japan)

    1995-02-28

    Prediction technology is introduced on the solidification and transformation of weld metals used for high performance stainless steel. A model has been developed which uses Thermo Calc, a multiple balanced calculation program, as a means to analyze the solidification of multi-component alloys including the polyphase solidification such as eutectic and peritectic. Verification has been in progress concerning the adequacy of this model and the adaptability as a practical steel. The following are the prediction technologies for solidification and transformation which have been derived from experiments and applied to welding techniques: the effects of nitrogen on the solidification mode and residual {gamma}quantity of a welding metal that is required for controlling the welding/solidification of high nitrogen content {gamma}system stainless steel; the structural control of weld metal for high corrosion resistance high Mo stainless steel, in which high Ni and high Mo contents are indispensable for attaining the optimum structure; the structural control of weld metal for two-phase stainless steel containing Mo and N, in which it is essential to secure a high nitrogen content and a {delta}/{gamma}phase balance in a weld metal; and the precipitation prediction of intermetallic compound in a high alloy weld metal for a high alloy stainless steel, for which an explanation is there by Cieslak et al. based on the phase stability theory. 22 refs., 16 figs.

  16. Dual phase vacuum extraction technology for the recovery of petroleum hydrocarbon contamination from the subsurface : a case study

    Energy Technology Data Exchange (ETDEWEB)

    Kallur, V.G.; Agar, J.G.; Wong, T.T.; Naus, J. [O' Connor Associates Environmental Inc., Calgary, AB (Canada); Michielsen, A.P. [Imperial Oil Ltd., Burnaby, BC (Canada)

    2003-07-01

    This paper presents a case history concerning the application of dual phase vacuum extraction (DPVE) technology for the remediation of subsurface petroleum hydrocarbon (PHC) contamination in silty soils at a service station site located in Vancouver, British Columbia. It also summarized the design and performance monitoring results for the site, in conjunction with the performance monitoring results from similar DPVE systems in operation at 7 other sites in western Canada. Each of these sites is underlain by both fine-grained and coarser grained sandy soils. The study offers useful design guidance and insight on the practical limitations of DPVE technology for PHC remediation. 2 refs., 6 tabs., 4 figs.

  17. Correlation Between Microstructures and Tensile Properties of Strain-Based API X60 Pipeline Steels

    Science.gov (United States)

    Sung, Hyo Kyung; Lee, Dong Ho; Lee, Sunghak; Kim, Hyoung Seop; Ro, Yunjo; Lee, Chang Sun; Hwang, Byoungchul; Shin, Sang Yong

    2016-06-01

    The correlation between the microstructures and tensile properties of strain-based American Petroleum Institute (API) X60 pipeline steels was investigated. Eight types of strain-based API X60 pipeline steels were fabricated by varying the chemical compositions, such as C, Ni, Cr, and Mo, and the finish cooling temperatures, such as single-phase and dual-phase regions. In the 4N and 5C steels, the volume fractions of bainitic ferrite (BF) and the secondary phases increased with the increasing C and adding Cr instead of Ni. In the 5C and 6NC steels, the volume fractions of acicular ferrite (AF) and BF decreased with increasing C and adding Ni, whereas the volume fractions of polygonal ferrite (PF) and the secondary phases increased. In the 6NC and 6NM steels, the volume fraction of BF was increased by adding Mo instead of Cr, whereas the volume fractions of PF and the secondary phases decreased. In the steels rolled in the single-phase region, the volume fraction of polygonal ferrite ranged from 40 to 60 pct and the volume fraction of AF ranged from 20 to 40 pct. In the steels rolled in the dual-phase region, however, the volume fraction of PF was more than 70 pct and the volume fraction of AF was below 20 pct. The strength of the steels with a high volume fraction of AF was higher than those of the steels with a high volume fraction of PF, whereas the yield point elongation and the strain hardening exponent were opposite. The uniform elongation after the thermal aging process decreased with increasing volume fraction of PF, whereas the uniform elongation increased with increasing volume fraction of AF. The strain hardening exponent increased with increasing volume fraction of PF, but decreased with increasing volume fraction of AF and effective grain size.

  18. A PIN diode controlled dual-tuned MRI RF coil and phased array for multi nuclear imaging

    Science.gov (United States)

    Ha, Seunghoon; Hamamura, Mark J.; Nalcioglu, Orhan; Tugan Muftuler, L.

    2010-05-01

    MR imaging of nuclei other than hydrogen has been used to investigate metabolism in humans and animals. However, MRI observable nuclei other than hydrogen are not as abundant and as a result the image SNR is lower. Dual-tuned radio frequency (RF) coils are developed for these studies in which high-resolution structural images are acquired using hydrogen and metabolic information is acquired by exciting the other nucleus. Using a dual-tuned coil, the experimenter avoids the inconvenience of moving the patient out and replacing the RF coil for imaging different nuclei. This also eliminates image registration problems. However, the common scheme of using trap circuits for dual-tuned operation results in increased coil losses as well as problems in obtaining optimal tuning and matching at both frequencies. Here, a new approach is presented using PIN diodes to switch the coil between two resonance frequencies. This design eliminates the need for the trap circuit and associated losses from the self-resistance of the trap circuit inductors. At the operating frequencies we used, the equivalent series resistance of an inductor is higher than that of the PIN diodes. In order to test the efficacy of this new approach, we first built two surface coils of identical geometry, one with the conventional trap circuits and one with the PIN diode switches. We also studied the performances of both coils when the coils are divided into shorter conductors segments by adding more tuning elements. It is known that dividing the coil into shorter conductor segments helps reduce radiation and electric field losses. We explored this effect for both coils at both operating frequencies. Finally, a dual-tuned receive-only phased array was designed and built with the PIN diode circuit to switch between two resonance frequencies. A conventional dual-tuned birdcage coil was designed and built to transmit RF power. A unique feature of this coil is that the RF power is fed through two separate sets

  19. Phased Array Ultrasonic Examination of Reactor Coolant System (Carbon Steel-to-CASS) Dissimilar Metal Weld Mockup Specimen

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, S. L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Cinson, A. D. [US Nuclear Regulatory Commission (NRC), Washington, DC (United States); Diaz, A. A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Anderson, M. T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-11-23

    In the summer of 2009, Pacific Northwest National Laboratory (PNNL) staff traveled to the Electric Power Research Institute (EPRI) NDE Center in Charlotte, North Carolina, to conduct phased-array ultrasonic testing on a large bore, reactor coolant pump nozzle-to-safe-end mockup. This mockup was fabricated by FlawTech, Inc. and the configuration originated from the Port St. Lucie nuclear power plant. These plants are Combustion Engineering-designed reactors. This mockup consists of a carbon steel elbow with stainless steel cladding joined to a cast austenitic stainless steel (CASS) safe-end with a dissimilar metal weld and is owned by Florida Power & Light. The objective of this study, and the data acquisition exercise held at the EPRI NDE Center, were focused on evaluating the capabilities of advanced, low-frequency phased-array ultrasonic testing (PA-UT) examination techniques for detection and characterization of implanted circumferential flaws and machined reflectors in a thick-section CASS dissimilar metal weld component. This work was limited to PA-UT assessments using 500 kHz and 800 kHz probes on circumferential flaws only, and evaluated detection and characterization of these flaws and machined reflectors from the CASS safe-end side only. All data were obtained using spatially encoded, manual scanning techniques. The effects of such factors as line-scan versus raster-scan examination approaches were evaluated, and PA-UT detection and characterization performance as a function of inspection frequency/wavelength, were also assessed. A comparative assessment of the data is provided, using length-sizing root-mean-square-error and position/localization results (flaw start/stop information) as the key criteria for flaw characterization performance. In addition, flaw signal-to-noise ratio was identified as the key criterion for detection performance.

  20. The eta phases and mechanical properties of TIG welded joints of WC-Co cemented carbide and steel

    Institute of Scientific and Technical Information of China (English)

    赵秀娟; 杨德新; 王浩; 高泽幸治; 田头孝介; 山森英明

    2004-01-01

    The tungsten-inert-gas (TIG) arc welding experiments of cemented carbide YG30 and steel 45 were carried out using the Ni-Fe-C filling alloys. The eta phases and mechanical properties of welded joints were analyzed by means of scanning electronic microscope (SEM), transmission electronic microscope (TEM) coupled with selected diffraction, electronic probe microanalysis and bending strength methods. The experimental results show that the chemical composition of the filling alloys affects eta phase formation. When the carbon and nickel contents in filling alloys are 0.61 wt% and 55.29 wt%, respectively, no eta phases form. And the joint bending strength is the highest to 1.352GPa. But if they are 0.01wt% and 55.38wt%, the eta phases are formed at the boundaries of the cemented carbide and the weld, and the thickness of eta phase layer is about 110 micrometers. And the joint bending strength is low. Usually, these eta phases are anomalously granular, and easy to accumulate at the boundaries between cemented carbides and the weld. They are multiple M6C rich in tungsten and iron.