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Sample records for 16mnd5 steel influence

  1. Influence of metallurgical phase transformation on crack propagation of 15-5PH stainless steel and 16MND5 low carbon steel

    International Nuclear Information System (INIS)

    This study focuses on the effects of phase transformations on crack propagation. We want to understand the changes of fracture toughness during welding. In this work, fracture toughness is expressed by J-integral. There are many experimental methods to obtain the critical toughness JIC but they are impractical for our investigation during phase transformation. That is the reason why we have proposed a method coupling mechanical tests, digital image correlation and finite element simulation. The fracture tests are implemented on pre-cracked single edge notched plate sample which is easy for machining and heat conduct during phase transformation. The tests are conducted at different temperatures until rupture. Digital image correlation gives us the displacement information on every sample. Each test is then simulated by finite element where the fracture toughness is evaluated by the method G-Theta at the crack propagation starting moment found by potential drop method and digital image correlation technical. Two materials have been studied, 15Cr-5Ni martensitic precipitation hardening stainless steel and 16MND5 ferritic low carbon steel. For these two materials, different test temperatures were chosen before, during and after phase transformation for testing and failure characterization of the mechanical behavior. Investigation result shows that metallurgical phase transformation has an influence on fracture toughness and further crack propagation. For 15-5PH, the result of J1C shows that the as received 15-5PH has higher fracture toughness than the one at 200 C. The toughness is also higher than the original material after one cycle heat treatment probably due to some residual austenite. Meanwhile, pure austenite 15-5PH at 200 C has higher fracture toughness than pure martensitic 15-5PH at 200 C. For 16MND5, the result also proves that the phase transformation affects fracture toughness. The as received material has bigger J1C than the situation where it was heated

  2. A micro-mechanical analysis and an experimental characterisation of the behavior and the damaging processes of a 16MND5 pressure vessel steel at low temperature; Etude micromecanique et caracterisation experimentale du comportement et de l'endommagement de l'acier de cuve 16MND5 a basses temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Pesci, R

    2004-06-15

    As part of an important experimental and numerical research program launched by Electricite De France on the 16MND5 pressure vessel steel, sequenced and in-situ tensile tests are realized at low temperatures [-196 C;-60 C]. They enable to associate the observation of specimens, the complete cartography of which has been made with a scanning electron microscope (damaging processes, initiation and propagation of microcracks), with the stress states determined by X-ray diffraction, in order to establish relevant criteria. All these measurements enable to supply a two-scale polycrystalline modeling of behavior and damage (Mori-Tanaka/self-consistent) which is developed concurrently with the experimental characterization. This model proves to be a very efficient one, since it correctly reproduces the influence of temperature experimentally defined: the stress state in ferrite remains less important than in bainite (the difference never exceeds 150 MPa), whereas it is much higher in cementite. The heterogeneity of strains and stresses for each crystallographic orientation is well rendered; so is cleavage fracture normal to the {l_brace}100{r_brace} planes in ferrite (planes identified by electron back scattered diffraction during an in-situ tensile test at -150 C), which occurs sooner when temperature decreases, for a constant stress of about 700 MPa in this phase. (author)

  3. Micro-mechanical analysis and modelling of the behavior and brittle fracture of a french 16MND5 steel: role of microstructural heterogeneities

    International Nuclear Information System (INIS)

    Reactor Pressure Vessel is the second containment barrier between nuclear fuel and the environment. Electricite de France's reactors are made with french 16MND5 low-alloyed steel (equ. ASTM A508 Cl.3). Various experimental techniques (scanning electron microscopy, X-ray diffraction...) are set up in order to characterize mechanical heterogeneities inside material microstructure during tensile testing at different low temperatures [-150 C;-60 C]. Heterogeneities can be seen as the effect of both 'polycrystalline' and 'composite' microstructural features. Interphase (until 150 MPa in average between ferritic and bainitic macroscopic stress state) and intra-phase (until 100 MPa in average between ferritic orientations) stress variations are highlighted. Modelling involves micro-mechanical description of plastic glide, mean fields models and realistic three-dimensional aggregates, all put together inside a multi-scale approach. Calibration is done on macroscopic stress-strain curves at different low temperatures, and modelling reproduces experimental stress heterogeneities. This modelling allows to apply a local micro-mechanical fracture criterion for crystallographic cleavage. Deterministic computations of time to fracture for different carbides random selection provide a way to express probability of fracture for the elementary volume. Results are in good agreement with hypothesis made by local approach to fracture. Hence, the main difference is that no dependence to loading nor microstructure features is supposed for probability of fracture on the representative volume: this dependence is naturally introduced by modelling. (author)

  4. Micro-mechanical analysis and modelling of the behavior and brittle fracture of a french 16MND5 steel: role of microstructural heterogeneities; Analyse et modelisation micromecanique du comportement et de la rupture fragile de l'acier 16MND5: prise en compte des heterogeneites microstructurales

    Energy Technology Data Exchange (ETDEWEB)

    Mathieu, J.Ph

    2006-10-15

    Reactor Pressure Vessel is the second containment barrier between nuclear fuel and the environment. Electricite de France's reactors are made with french 16MND5 low-alloyed steel (equ. ASTM A508 Cl.3). Various experimental techniques (scanning electron microscopy, X-ray diffraction...) are set up in order to characterize mechanical heterogeneities inside material microstructure during tensile testing at different low temperatures [-150 C;-60 C]. Heterogeneities can be seen as the effect of both 'polycrystalline' and 'composite' microstructural features. Interphase (until 150 MPa in average between ferritic and bainitic macroscopic stress state) and intra-phase (until 100 MPa in average between ferritic orientations) stress variations are highlighted. Modelling involves micro-mechanical description of plastic glide, mean fields models and realistic three-dimensional aggregates, all put together inside a multi-scale approach. Calibration is done on macroscopic stress-strain curves at different low temperatures, and modelling reproduces experimental stress heterogeneities. This modelling allows to apply a local micro-mechanical fracture criterion for crystallographic cleavage. Deterministic computations of time to fracture for different carbides random selection provide a way to express probability of fracture for the elementary volume. Results are in good agreement with hypothesis made by local approach to fracture. Hence, the main difference is that no dependence to loading nor microstructure features is supposed for probability of fracture on the representative volume: this dependence is naturally introduced by modelling. (author)

  5. Numerical modelling of Charpy-V notch test by local approach to fracture. Application to an A508 steel in the ductile-brittle transition range; Modelisation de l'essai Charpy par l'approche locale de la rupture. Application au cas de l'acier 16MND5 dans le domaine de transition

    Energy Technology Data Exchange (ETDEWEB)

    Tanguy, B

    2001-07-15

    Ferritic steels present a transition of the rupture mode which goes progressively of a brittle rupture (cleavage) to a ductile rupture when the temperature increases. The following of the difference of the transition temperature of the PWR vessel steel by the establishment of toughness curves makes of the Charpy test an integrating part of the monitoring of the French PWR reactors. In spite of the advantages which are adapted to it in particular its cost, the Charpy test does not allow to obtain directly a variable which characterizes a crack propagation resistance as for instance the toughness used for qualifying the mechanical integrity of a structure. This work deals with the establishment of the through impact strength-toughness in the transition range of the vessel steel: 16MND5 from a non-empirical approach based on the local approach of the rupture. The brittle rupture is described by the Beremin model (1983), which allows to describe the dispersion inherent in this rupture mode. The description of the brittle fissure is carried out by the GTN model (1984) and by the Rousselier model (1986). This last model has been modified in order to obtain a realistic description of the brittle damage in the case of fast solicitations and of local heating. The method proposed to determine the parameters of the damage models depends only of tests on notched specimens and of the inclusion data of the material. The behaviour is described by an original formulation parametrized in temperature which allows to describe all the tests carried out in this study. Before using this methodology, an experimental study of the behaviour and of the rupture modes of the steel 16MND5 has been carried out. From the toughness tests carried out in quasi-static and dynamical conditions, it has been revealed that this steel does not present important unwedging of its toughness curve due to the velocity effect. In the transition range, local heating of about 150 C have been measured in the root

  6. Characterization of PWR vessel steel tearing under severe accident condition temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Matheron, Philippe, E-mail: philippe.matheron@cea.fr [CEA, DEN, DM2S, SEMT, F-91191 Gif-sur-Yvette (France); Chapuliot, Stephane, E-mail: stephane.chapuliot@cea.fr [CEA, DEN, DM2S, SEMT, F-91191 Gif-sur-Yvette (France); Nicolas, Laetitia, E-mail: laetitia.nicolas@cea.fr [CEA, DEN, DM2S, SEMT, F-91191 Gif-sur-Yvette (France); Laboratoire de Mecanique des Structures Industrielles Durables, UMR CNRS-EDF 2832, 1 avenue du General de Gaulle, F-92141 Clamart (France); Koundy, Vincent, E-mail: vincent.koundy@irsn.fr [IRSN-DSR, Service d' evaluation des Accidents Graves et des Rejets radioactifs B.P. 17, 92262 Fontenay-aux-Roses Cedex (France); Caroli, Cataldo, E-mail: cataldo.caroli@irsn.fr [IRSN-DSR, Service d' evaluation des Accidents Graves et des Rejets radioactifs B.P. 17, 92262 Fontenay-aux-Roses Cedex (France)

    2012-01-15

    to different types of rupture behaviour at high temperatures. The experimental programme has been conducted on various French RPV 16MND5 steels for temperatures ranging from 900 Degree-Sign C to 1100 Degree-Sign C. Comparisons between the tests performed on these various 16MND5 steels show that this approach is appropriate to characterize the difference in ductility observed at high temperatures. The aim of this experimental study is also to contribute to the definition of a tearing criterion by identifying, on the basis of CT results, the related material parameters at temperatures representative of the real severe accident conditions. This experimental campaign has been carried out in partnership with IRSN in the framework of a research programme whose purpose is to complete the mechanical properties database of 16MND5 steel and to model tearing failure in French RPV lower head vessels under severe conditions ().

  7. Microbially Influenced Corrosion of Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yong Deuk; Ryu, Seung Ki; Kim Young Ho [POSCO Techanical Researh Laboratories, Pohang (Korea, Republic of)

    1996-06-25

    Microbially Influenced Corrosion(MIC) is often a significant factor in controlling the long-term performance of most structural materials in industrial applications. This papers cover MIC mechanism and evaluation of stainless steels in soil and sea water environments. Papers also cover detection, monitoring and mitigation of MIC, biocides and treatments. (author). 28 refs., 2 tabs., 5 figs.

  8. Influence of the steel scrap classes on the liquid steel output molten in electric steel processes

    Directory of Open Access Journals (Sweden)

    K. Janiszewski

    2012-12-01

    Full Text Available Purpose: This is why we have analysed in the paper, using statistical analysing methods, the influence of use in the electric arc furnace charges of steel scrap of different qualities on the index of liquid steel output from a melt.Design/methodology/approach: The used research methodology consists in analytical simulation of variations in mass of liquid steel obtained from melts differing in steel scrap content in the metallic charge and statistical analyses of industrial results acquired from the corresponding process documentation (so called melt cards.Findings: Basing on the analytical and statistical analyses carried out we have determine resulting variations in the liquid steel per melt ratios depending on the content of steel scrap in the metallic charge.Research limitations/implications: The research results obtained can be utilized in each steelmaking facility, which employs the Electric Steelmaking process, in order to “design” the metallic charge compositions, having in view the quality and economic aspects.Practical implications: The research results presented in the paper can be used for steel production of high purity steels.Originality/value: The results presented in this paper are directed to the steelmakers employing the Electric Steelmaking process and constitute the authors’ original study.

  9. Microbially influenced corrosion of carbon steels

    Energy Technology Data Exchange (ETDEWEB)

    White, D.C.; Jack, R.F.; Dowling, N.J.E.; Franklin, M.J.; Nivens, D.E.; Brooks, S.; Mittelman, M.W.; Vass, A.A. (Tennessee Univ., Knoxville, TN (USA). Inst. for Applied Microbiology); Isaacs, H.S. (Brookhaven National Lab., Upton, NY (USA))

    1990-01-01

    Microbially influenced corrosion of pipeline steels is an economically important problem. Microbes form tubercles which block fluid flow and can facilitate localized corrosion leading to through-wall penetrations. Microbes of diverse physiological types and metabolic potentialities have been recovered from fresh tubercles or under-deposit corrosion and have been characterized. In tests utilizing sterilizable flow-through systems containing pipeline steel coupons, corrosion rates determined by nondestructive electrochemical means have indicated that increasing the number of physiological types of microbes inoculated into the system generally increased the severity of the microbially influenced corrosion (MIC). This study reports the MIC of monocultures and combinations of monocultures in an aerobic fresh water system with low sulfate and an anaerobic saline system. In both the aerobic and anaerobic systems, the combination of microbes induced greater MIC responses than the monocultures. In tests involving a combination of microbes in both systems in which one member was a sulfate-reducing bacteria (SRB), the corrosion mechanism was different for the control and the monocultures. This difference was indicated by the phase shift in the electrochemical impedance spectra (EIS). The localization of corrosion, that in many cases is the hallmark of MIC, may be initiated by the inhomogeneities of supposedly smooth metal surfaces. The scanning vibrating electrode technique (SVET) demonstrated non-uniform current densities over carbon steel electrodes polished to a 600 grit finish suggesting pitting and repassivation of pits in sterile medium.

  10. Monitoring Techniques for Microbially Influenced Corrosion of Carbon Steel

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel

    2000-01-01

    Abstract Monitoring Techniques for Microbially Influenced Corrosion of Carbon Steel Microbially influenced corrosion (MIC) of carbon steel may occur in media with microbiological activity of especially sulphate-reducing bacteria, e.g. on pipelines buried in soil and on marine structures. MIC of c...

  11. FACTORS INFLUENCING THE WEAR BEHAVIOR OF PM STEELS

    Institute of Scientific and Technical Information of China (English)

    J.A. Wang; H. Danninger

    2001-01-01

    A review was made on the research progress of wear behavior of PM steels in recentyears. Wear is not an intrinsic property of PM steels, which is strongly influencedby the wear test conditions. However, many other factors that determine the me-chanical properties of PM steels also affect the wear behavior. Porosity has differenteffects on the wear of PM steels depending on the application conditions. Under drysliding condition, higher porosity results in lower wear resistance. The influence ofmicrostructures on wear resistance was in the order: carbide, martensite, bainite andlamellar pearlite. The wear resistance increases with hardness, but this relationshipchanges with the porosity and microstructures of PM steels.``

  12. Monitoring Techniques for Microbially Influenced Corrosion of Carbon Steel

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel

    2000-01-01

    Microbially influenced corrosion (MIC) of carbon steel may occur in media with microbiological activity of especially sulphate-reducing bacteria, e.g. on pipelines buried in soil and on marine structures. MIC of carbon steel must be monitored on-line in order to provide an efficient protection...

  13. Formation mechanism of solute clusters under neutron irradiation in ferritic model alloys and in a reactor pressure vessel steel: clusters of defects; Mecanismes de fragilisation sous irradiation aux neutrons d'alliages modeles ferritiques et d'un acier de cuve: amas de defauts

    Energy Technology Data Exchange (ETDEWEB)

    Meslin-Chiffon, E

    2007-11-15

    The embrittlement of reactor pressure vessel (RPV) under irradiation is partly due to the formation of point defects (PD) and solute clusters. The aim of this work was to gain more insight into the formation mechanisms of solute clusters in low copper ([Cu] = 0.1 wt%) FeCu and FeCuMnNi model alloys, in a copper free FeMnNi model alloy and in a low copper French RPV steel (16MND5). These materials were neutron-irradiated around 300 C in a test reactor. Solute clusters were characterized by tomographic atom probe whereas PD clusters were simulated with a rate theory numerical code calibrated under cascade damage conditions using transmission electron microscopy analysis. The confrontation between experiments and simulation reveals that a heterogeneous irradiation-induced solute precipitation/segregation probably occurs on PD clusters. (author)

  14. Influence of carbon steel grade on the initial attachment of bacteria and microbiologically influenced corrosion.

    Science.gov (United States)

    Javed, M A; Neil, W C; Stoddart, P R; Wade, S A

    2016-01-01

    The influence of the composition and microstructure of different carbon steel grades on the initial attachment (≤ 60 min) of Escherichia coli and subsequent longer term (28 days) corrosion was investigated. The initial bacterial attachment increased with time on all grades of carbon steel. However, the rate and magnitude of bacterial attachment varied on the different steel grades and was significantly less on the steels with a higher pearlite phase content. The observed variations in the number of bacterial cells attached across different steel grades were significantly reduced by applying a fixed potential to the steel samples. Longer term immersion studies showed similar levels of biofilm formation on the surface of the different grades of carbon steel. The measured corrosion rates were significantly higher in biotic conditions compared to abiotic conditions and were found to be positively correlated with the pearlite phase content of the different grades of carbon steel coupons. PMID:26785935

  15. Ductile-to-brittle transition in a low alloy steel

    International Nuclear Information System (INIS)

    The mechanical properties of pressure vessel steel (and above all its resistance to brittle fracture) are a decisive factor in the complex safety assessment of nuclear power plants. The monitoring of neutron induced embrittlement is provided using Charpy impact tests on standard V-notch specimens due to their small size. Material's ductile-to-brittle transition temperature (DBTT) can be easily characterised using this test. However, Charpy impact energy cannot be immediately used for safety assessment, since fracture toughness is required. Some empirical formulas have been developed, but no direct relationship was still found. When the specimens are tested in the ductile-to-brittle transition region, cleavage crack initiation is preceded by ductile crack growth giving a large scatter to the values of fracture toughness and/or Charpy impact energy. Even if the cleavage initiation and propagation in steels containing isolated spheroidic carbides are qualitatively well understood, no one from existing models can explain the sharp upturn in ductile-to-brittle transition region. In the present work, French tempered bainitic steel 16MND5 (considered as equivalent to the American standard A508 Cl.3) is studied: The large fractographic analysis of CT and Charpy specimens broken in the DBTT range is undertaken to account for the evolution of cleavage fracture mechanisms. In addition to classical scanning electron microscopy, transmission electron microscopy and EBSD technique are used in order to study the propagation of cleavage crack. The classical fracture mechanics using KIc or Jc concepts can hardly describe the unstable brittle fracture in the DBTT range. Hence, the local approach, which aims to predict the fracture of any structural component using local criteria, providing that the mechanical fields in the structure are known, is used. The probability of cleavage fracture in the DBTT range is predicted using the Beremin model based on weakest link theory, e.g. 2

  16. The Influence of Niobium on SSC Resistance in API Steels

    Energy Technology Data Exchange (ETDEWEB)

    Malina, J.; Malina, M.; Novosel-Radovic, V. [Zagreb Univ., Faculty of Metallurgy (Croatia)

    2004-07-01

    Full text of publication follows: Oil country tubular goods are often exposed to aggressive sour environments in oil wells where H{sub 2}S promotes sulfide stress cracking, SSC. This is one of the most dangerous corrosion phenomena characterized by unpredictable and sudden cracking of steel constructions in service. SSC results in a variety of fracture features having a common relationship to the presence of hydrogen in metal and therefore it belongs to hydrogen embrittlement phenomena, HE. For the production of sulfide stress cracking resistant (SSC) tubing from steels included in Group 3 of API Specification 5CT, in this study two experimental Cr-Mo steels (without niobium and with niobium microalloyed) were tested. The influence of Nb precipitates in pipeline steels on the sensitivity to sulfide stress cracking was examined in laboratory experiments using three point bent beam tests. High mechanical properties were achieved through quenching and tempering procedures. Better corrosion resistance of Nb-containing steel is the consequence of microstructural parameters obtained through strengthening mechanism with microalloying element. Besides the usual mechanical, metallographic, SEM and TEM analyses, as complementary method the X-ray diffraction was used. It was revealed that tetragonality of crystal lattice, dislocation density and residual stresses are in good correlation with Sc-vales from corrosion tests. Nb precipitates (especially niobium carbides) have beneficial influence when producing the steels with low sensitivity to SSC. (authors)

  17. Impact Study of Stainless Steel Cold-cladding Process on Mn-Ni-Mo Low-alloy Steel Property%不锈钢冷堆工艺对锰镍钼低合金钢性能的影响研究

    Institute of Scientific and Technical Information of China (English)

    黄炳炎; 刘全印; 余平; 刘清会

    2016-01-01

    核岛主设备承压边界一般采用锰镍钼低合金钢材料制造,与冷却剂接触的低合金钢内表面需要堆焊耐蚀奥氏体不锈钢。为研究不锈钢冷堆工艺(首层预热,后续堆焊层不预热)对低合金钢母材热影响区性能的影响,采用带极堆焊和手工电弧焊堆焊两种冷堆工艺在16MND5低合金钢试板上进行了不锈钢堆焊试验,对堆焊试板进行了硬度、弯曲、逐层金相和逐层磁粉检验等一系列试验和检验。试验结果表明,采用冷堆工艺在锰镍钼低合金钢上堆焊奥氏体不锈钢的质量是可靠的。%The pressure boundary materials of nuclear islands main equipment generally used Mn-Ni-Mo low-alloy steel materials,and inner surface of low-alloy steels in contact with coolant fluid need to weld overlay cladding of austenitic stainless steel for corrosion resistance.In order to study the impact that cold-cladding process(the first layer preheating and the subsequent layers no preheating)append on property of low-alloy steel HAZ,the stainless steel cladding coupons are respectively executed with strip overlay welding and shielded metal-arc overlay welding on 16MND5 low-alloy steel,and undergo a series of tests and examinations,such as hardness measurements,bend tests,layer-by-layer metallographic examination and layer-by-layer magnetic particle examination.The test results show that the joints quality is reliable when overlay cladding of austenitic stainless steel on Mn-Ni-Mo low-alloy steel surface is welded with cold-cladding process.

  18. Microbially influenced corrosion of stainless steels in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, U.P.; Wolfram, J.H.; Rogers, R.D.

    1990-01-01

    This paper reviews the components, causative agents, corrosion sites, and potential failure modes of stainless steel components susceptible to microbially influenced corrosion (MIC). The stainless steel components susceptible to MIC are located in the reactor coolant, emergency, and reactor auxiliary systems, and in many plants, in the feedwater train and condenser. The authors assessed the areas of most high occurrence of corrosion and found the sites most susceptible to MIC to the heat-affected zones in the weldments of sensitized stainless steel. Pitting is the predominant MIC corrosion mechanisms, caused by sulfur reducing bacteria (SRB). Also discussed is the current status of the diagnostic, preventive, and mitigation techniques, including use of improved water chemistry, alternate materials, and improved thermomechanical treatments. 37 refs., 3 figs.

  19. Propagation and arrest of cleavage cracks in a nuclear pressure vessel steel

    International Nuclear Information System (INIS)

    The safety of nuclear structures is crucial while the service time of nuclear power stations is planned to be extended up to 60 years. Initiation stage of cracks is still considered as a key issue, but more and more component integrity analyses investigate the crack arrest possibility. This study deals with physical mechanisms of cleavage crack propagation and numerical computations related to brittle fracture. Experiments using standard measuring techniques and a high-speed framing camera system, as well as Scanning Electron Microscope fracture surface analyses were carried out on thin CT specimens made of 16MND5 PWR vessel steel. The elastic-viscoplastic behavior of the ferritic steel has been studied and taken into account in numerical simulations. The extended Finite Element Method (X-FEM) is used in CAST3M finite element analysis software to model crack propagation. Numerical computations combine a local non-linear dynamic approach and a fracture criterion based on critical cleavage stress, whereas current standards in the nuclear field use a global static approach to fracture to depict crack initiation and arrest. The links of the criterion with temperature and strain rate are considered thanks to experiments, SEM fractographies and 2D computations in order to get a robust physical model which can be effective for model-based predictions of industrial structures. (authors)

  20. Microbial-Influenced Corrosion of Corten Steel Compared with Carbon Steel and Stainless Steel in Oily Wastewater by Pseudomonas aeruginosa

    Science.gov (United States)

    Mansouri, Hamidreza; Alavi, Seyed Abolhasan; Fotovat, Meysam

    2015-07-01

    The microbial corrosion behavior of three important steels (carbon steel, stainless steel, and Corten steel) was investigated in semi petroleum medium. This work was done in modified nutrient broth (2 g nutrient broth in 1 L oily wastewater) in the presence of Pseudomonas aeruginosa and mixed culture (as a biotic media) and an abiotic medium for 2 weeks. The behavior of corrosion was analyzed by spectrophotometric and electrochemical methods and at the end was confirmed by scanning electron microscopy. The results show that the degree of corrosion of Corten steel in mixed culture, unlike carbon steel and stainless steel, is less than P. aeruginosa inoculated medium because some bacteria affect Corten steel less than other steels. According to the experiments, carbon steel had less resistance than Corten steel and stainless steel. Furthermore, biofilm inhibits separated particles of those steels to spread to the medium; in other words, particles get trapped between biofilm and steel.

  1. Anticorrosive Influence of Acetobacter aceti Biofilms on Carbon Steel

    Science.gov (United States)

    France, Danielle Cook

    2016-07-01

    Microbiologically influenced corrosion (MIC) of carbon steel infrastructure is an emerging environmental and cost issue for the ethanol fuel industry, yet its examination lacks rigorous quantification of microbiological parameters that could reveal effective intervention strategies. To quantitatively characterize the effect of cell concentration on MIC of carbon steel, numbers of bacteria exposed to test coupons were systematically controlled to span four orders of magnitude throughout a seven-day test. The bacterium studied, Acetobacter aceti, has been found in ethanol fuel environments and can convert ethanol to the corrosive species acetic acid. A. aceti biofilms formed during the test were qualitatively evaluated with fluorescence microscopy, and steel surfaces were characterized by scanning electron microscopy. During exposure, biofilms developed more quickly, and test reactor pH decreased at a faster rate, when cell exposure was higher. Resulting corrosion rates, however, were inversely proportional to cell exposure, indicating that A. aceti biofilms are able to protect carbon steel surfaces from corrosion. This is a novel demonstration of corrosion inhibition by an acid-producing bacterium that occurs naturally in corrosive environments. Mitigation techniques for MIC that harness the power of microbial communities have the potential to be scalable, inexpensive, and green solutions to industrial problems.

  2. Anticorrosive Influence of Acetobacter aceti Biofilms on Carbon Steel

    Science.gov (United States)

    France, Danielle Cook

    2016-09-01

    Microbiologically influenced corrosion (MIC) of carbon steel infrastructure is an emerging environmental and cost issue for the ethanol fuel industry, yet its examination lacks rigorous quantification of microbiological parameters that could reveal effective intervention strategies. To quantitatively characterize the effect of cell concentration on MIC of carbon steel, numbers of bacteria exposed to test coupons were systematically controlled to span four orders of magnitude throughout a seven-day test. The bacterium studied, Acetobacter aceti, has been found in ethanol fuel environments and can convert ethanol to the corrosive species acetic acid. A. aceti biofilms formed during the test were qualitatively evaluated with fluorescence microscopy, and steel surfaces were characterized by scanning electron microscopy. During exposure, biofilms developed more quickly, and test reactor pH decreased at a faster rate, when cell exposure was higher. Resulting corrosion rates, however, were inversely proportional to cell exposure, indicating that A. aceti biofilms are able to protect carbon steel surfaces from corrosion. This is a novel demonstration of corrosion inhibition by an acid-producing bacterium that occurs naturally in corrosive environments. Mitigation techniques for MIC that harness the power of microbial communities have the potential to be scalable, inexpensive, and green solutions to industrial problems.

  3. Factors influencing the surface quality of polished tool steels

    International Nuclear Information System (INIS)

    Today’s demands on surface quality of moulds for injection moulding of plastic components involve no/low defect contents and roughness levels in the nm-range for high gloss applications. Material properties as well as operating conditions influence the mould finish, and thus the final surface of moulded products. This paper focuses on how particle content and different polishing strategies influence final surface qualities of moulds. Visual estimations of polished tool steel samples were combined with non-contact 3D-surface texture analysis in order to correlate traditional assessments to more quantitative methods, and to be able to analyse the surfaces at nanometre-level. It was found that steels with a lower proportion of particles, like carbides and oxides, gave rise to smoother polished surfaces. In a comparative study of polishers from different polishing shops, it was found that while different surface preparation strategies can lead to similar final roughness, similar preparation techniques can produce high-quality surfaces from different steel grades. However, the non-contact 3D-surface texture analysis showed that not all smooth polished surfaces have desirable functional topographies for injection moulding of glossy plastic components. (paper)

  4. INFLUENCE OF ELECTRIC SPARK ON HARDNESS OF CARBON STEEL

    Directory of Open Access Journals (Sweden)

    I. O. Vakulenko

    2014-03-01

    Full Text Available Purpose. The purpose of work is an estimation of influence of an electric spark treatment on the state of mouldable superficial coverage of carbon steel. Methodology. The steel of fragment of railway wheel rim served as material for research with chemical composition 0.65% С, 0.67% Mn, 0.3% Si, 0.027% P, 0.028% S. Structural researches were conducted with the use of light microscopy and methods of quantitative metallography. The structural state of the probed steel corresponded to the state after hot plastic deformation. The analysis of hardness distribution in the micro volumes of cathode metal was carried out with the use of microhardness tester of type of PMT-3. An electric spark treatment of carbon steel surface was executed with the use of equipment type of EFI-25M. Findings. After electric spark treatment of specimen surface from carbon steel the forming of multi-layered coverage was observed. The analysis of microstructure found out the existence of high-quality distinctions in the internal structure of coverage metal, depending on the probed area. The results obtained in the process are confirmed by the well-known theses, that forming of superficial coverage according to technology of electric spark is determined by the terms of transfer and crystallization of metal. The gradient of structures on the coverage thickness largely depends on development of structural transformation processes similar to the thermal character influence. Originality. As a result of electric spark treatment on the condition of identical metal of anode and cathode, the first formed layer of coverage corresponds to the monophase state according to external signs. In the volume of coverage metal, the appearance of carbide phase particles is accompanied by the decrease of microhardness values. Practical value. Forming of multi-layered superficial coverage during electric spark treatment is accompanied by the origin of structure gradient on a thickness. The effect

  5. Influence of Trace Alloying Elements on Corrosive Resistance of Cast Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    DUAN Han-qiao; YAN Xiang; WEI Bo-kang; LIN Han-tong

    2005-01-01

    The influences of trace alloying elements niobium, vanadium and zirconium on the corrosive resistance of 18-8 type cast stainless steel have been studied in deta() orthogonal design experiments. The results show that zirconium is mainly in the form of compound inclusions, which is unfavorable to promote the corrosive resistance of the cast stainless steel. It can alleviate the disadvantageous influence of carbon addition on corrosive resistance when some elements such as vanadium and niobium exist in the steel, and niobium has a remarkable influence on the intergranular corrosive resistance but unobvious on the pitting corrosion, and vanadium has a slightly favorable influence on the corrosive resistance of the steel.

  6. Possible influences on textures in unalloyed steels and their effects on steel properties

    International Nuclear Information System (INIS)

    Textures in steels play an essential role for applications where anisotropic properties are favourable. For the example of deep-drawing steel sheet the correlation between parameters characterising the behaviour in the deep-drawing process, as Lankford r-value and planar anisotropy Δr, and the crystallographic texture is considered. Furthermore, the development of texture in the course of manufacturing cold strip is followed for unalloyed and microalloyed deep-drawing grades. For representation of typical features of textures the method of orientation distribution functions (ODF) together with the description of texture by characteristic fibres is used. In detail, the parameters influencing textures, such as chemical composition, finishing temperature in the hot-rolling mill (in relation to the austenite or ferrite region), transformation behaviour, cold-rolling reduction and the course of temperature during recrystallizing annealing, are discussed. From the given survey it may be concluded, that in the manufacturing process there are many possibilities to control the texture of the finished product. Finally, it is shown that the impact of textures on the r-value can be calculated with high precision. On the other hand, the formation of texture itself, particularly during hot-rolling, transformation and recrystallization after cold-rolling, at present can be calculated and modelled only in simple cases. (orig.)

  7. Influence of Material Flow in Steel Manufacturing Process on Atmosphere Environmental Load

    Institute of Scientific and Technical Information of China (English)

    DU Tao; CAI Jiu-ju; LU Zhong-wu; QI Yuan-hong; ZHANG Chun-xia

    2004-01-01

    The standard material flow diagram in steel manufacturing process was proposed to analyze the influences of various material flows on environmental load of 1 t of final product. Two influence factors and reducing measures of environmental load were pointed out. The environmental load was appraised for a typical technological process in a Chinese steel plant.

  8. Microbially influenced corrosion of stainless steel by manganese oxidizing microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Linhardt, P. [Technische Universitaet Wien, Technische Versuchs- und Forschungsanstalt (TVFA), Karlsplatz 13, 1040 Wien (Austria)

    2004-03-01

    Based on the corrosion behaviour of stainless steels in fresh water and on the electrochemical properties of higher manganese oxides, the mechanism ''Microbially influenced corrosion by manganese oxidizing microorganisms'' (MIC by MOMOs) is presented as the consequence of biomineralized manganese oxides in contact with the metal. Localized corrosion may develop at elevated but normally undercritical chloride concentration in the water. The mechanism was found useful in the analysis of certain cases of unexpected failure of stainless steel in fresh water. (Abstract Copyright [2004], Wiley Periodicals, Inc.) [German] Ausgehend vom Korrosionsverhalten nichtrostender Staehle in Suesswasser und den elektrochemischen Eigenschaften hoeherer Manganoxide wird der Mechanismus ''Mikrobiell beeinflusste Korrosion durch manganoxidierende Mikroorganismen'' als die Folge des Kontaktes von biomineralisiertem Braunstein mit dem metallischen Werkstoff beschrieben. Unter diesen Bedingungen kann Lokalkorrosion bei Chloridkonzentrationen im Wasser entstehen, die normalerweise als unkritisch angesehen werden. Der Mechanismus hat sich bei der Schadensanalyse bestimmter, unerwarteter Korrosionsfaelle bewaehrt. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  9. The influence of cold work on the oxidation behaviour of stainless steel

    International Nuclear Information System (INIS)

    In this thesis the study of the interaction of oxygen gas with stainless steel surfaces is described. Thermogravimetry, microscopy and ellipsometry have been used to follow the oxidation in situ, while EDX, AES and XPS have been used to determine the oxide compositions. The aim of this thesis is to reveal the influence on the oxidation behaviour of stainless steel of i) cold work (rolling, drawing, milling, polishing and Ar ion bombardment) ii) the initially formed oxide and iii) the experimental conditions. Two types of stainless steels have been used (AISI 304 (a 18/8 Cr/Ni steel) and Incoloy 800 H (a 20/30 Cr/Ni steel)). (Auth.)

  10. Deformation studies from in situ SEM experiments of a reactor pressure vessel steel at room and low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Latourte, F., E-mail: felix.latourte@edf.fr [EDF R and D, Materials and Mechanics of Components, Avenue des Renardières, Ecuelles, 77818 Moret-sur-Loing Cedex (France); Salez, T. [EDF R and D, Materials and Mechanics of Components, Avenue des Renardières, Ecuelles, 77818 Moret-sur-Loing Cedex (France); Guery, A. [EDF R and D, Materials and Mechanics of Components, Avenue des Renardières, Ecuelles, 77818 Moret-sur-Loing Cedex (France); LMT-Cachan (ENS de Cachan/CNRS/PRES UniverSud Paris), 61 avenue du Président Wilson, F-94235 Cachan (France); Rupin, N.; Mahé, M. [EDF R and D, Materials and Mechanics of Components, Avenue des Renardières, Ecuelles, 77818 Moret-sur-Loing Cedex (France)

    2014-11-15

    This paper presents the strain fields acquired at micro-structural scale for a pressure vessel steel, used in the French pressurized water reactors (PWR) and designated as 16MND5 or ASTM A508cl3. The experimental observations rely on specific specimen preparation, prior crystallographic orientation characterization by means of electron backscatter diffraction (EBSD), surface patterning using lithography and chemical etching. The specimens are loaded using a miniaturized tensile stage fitted within a scanning electron microscope (SEM) chamber, and images acquired of a small area are used to measure displacement and strain fields using a Digital Image Correlation (DIC) technique. In addition, a specific setup allowed to cool down to −100 °C the specimen during the whole tensile test and the image acquisition. The experimental apparatus and the kinematic field measurements are introduced in two first sections of the paper. Then the results will be presented for two experiments, one conducted at room temperature and the other at −100 °C, including a comparison of strain localization features and a preliminary comparison of plasticity mechanisms.

  11. Influence of remanent magnetization on pitting corrosion in pipeline steel

    Energy Technology Data Exchange (ETDEWEB)

    Espina-Hernandez, J. H. [ESIME Zacatenco, SEPI Electronica Instituto Politecnico Nacional Mexico, D. F. (Mexico); Caleyo, F.; Hallen, J. M. [DIM-ESIQIE, Instituto Politecnico Nacional Mexico D. F. (Mexico); Lopez-Montenegro, A.; Perez-Baruch, E. [Pemex Exploracion y Produccion, Region Sur Villahermosa, Tabasco (Mexico)

    2010-07-01

    Statistical studies performed in Mexico indicate that leakage due to external pitting corrosion is the most likely cause of failure of buried pipelines. When pipelines are inspected with the magnetic flux leakage (MFL) technology, which is routinely used, the magnetization level of every part of the pipeline changes as the MFL tool travels through it. Remanent magnetization stays in the pipeline wall after inspection, at levels that may differ from a point to the next. This paper studies the influence of the magnetic field on pitting corrosion. Experiments were carried out on grade 52 steel under a level of remanent magnetization and other laboratory conditions that imitated the conditions of a pipeline after an MLF inspection. Non-magnetized control samples and magnetized samples were subjected to pitting by immersion in a solution containing chlorine and sulfide ions for seven days, and then inspected with optical microscopy. Results show that the magnetic field in the pipeline wall significantly increases pitting corrosion.

  12. On key factors influencing ductile fractures of dual phase (DP) steels

    International Nuclear Information System (INIS)

    In this paper, we examine the key factors influencing ductile failure of various grades of dual phase (DP) steels using the microstructure-based modeling approach. Various microstructure-based finite element models are generated based on the actual microstructures of DP steels with different martensite volume fractions. These models are, then, used to investigate the influence of ductility of the constituent ferrite phase and also the influence of voids introduced in the ferrite phase on the overall ductility of DP steels. It is found that with volume fraction of martensite in the microstructure less than 15%, the overall ductility of the DP steels strongly depends on the ductility of the ferrite matrix, hence pre-existing micro-voids in the microstructure significantly reduce the overall ductility of the steel. When the volume fraction of martensite is above 15%, the pre-existing voids in the ferrite matrix does not significantly reduce the overall ductility of the DP steels, and the overall ductility is more influenced by the mechanical property disparity between the two phases. The applicability of the phase inhomogeneity driven ductile failure of DP steels is then discussed based on the obtained computational results for various grades of DP steels, and the experimentally obtained scanning electron microscopy (SEM) pictures of the corresponding grades of DP steels near fracture surface are used as evidence for result validations.

  13. MORPHOLOGY MODIFICATION OF CARBON CHROME MOLYBDENUM STEEL STRUCTURE INFLUENCED BY HEAT TREATMENT

    Directory of Open Access Journals (Sweden)

    V. A. Lutsenko

    2011-01-01

    Full Text Available The influence of temperature and time parameters of thermal treatment on structural change and properties of carbon chromium molybdenum steel has been studied. It has been shown that there are considerable areas with grainy morphology of cementite after high temperature tempering in the structure of steel. It assures reduction of steel microhardness by 25%, and there are no substantial structural changes after medium temperature tempering.

  14. Morphology modification of carbon chrome molybdenum steel structure influenced by heat treatment

    OpenAIRE

    V. A. Lutsenko; N. L. Anelkin; T. N. Golubenko; Scherbakov, V. I.; O. V. Lutsenko

    2011-01-01

    The influence of temperature and time parameters of thermal treatment on structural change and properties of carbon chromium molybdenum steel has been studied. It has been shown that there are considerable areas with grainy morphology of cementite after high temperature tempering in the structure of steel. It assures reduction of steel microhardness by 25%, and there are no substantial structural changes after medium temperature tempering.

  15. Influence of hydrogen on corrosion and stress induced cracking of stainless steel

    OpenAIRE

    Kivisäkk, Ulf

    2010-01-01

    Hydrogen is the smallest element in the periodical table. It has been shown in several studies that hydrogen has a large influence on the corrosion and cracking behaviour of stainless steels. Hydrogen is involved in several of the most common cathode reactions during corrosion and can also cause embrittlement in many stainless steels. Some aspects of the effect of hydrogen on corrosion and hydrogen-induced stress cracking, HISC, of stainless steels were studied in this work. These aspects rel...

  16. Influence of smelting processes on precipitation behaviors and mechanical properties of low activation ferrite steels

    International Nuclear Information System (INIS)

    Research highlights: → Creep properties could be improved dramatically by control of smelting process. → VIM + ESR smelting process could improve the W macrosegregation. → W could accelerate the transition of M7C3 to M23C6 in RAFM steel. → The synergetic effect of carbides and tungsten depletion of solid solution lead to the decrease in creep resistance. - Abstract: In this paper, the influence of smelting processes on precipitation behaviors and mechanical properties of CLF-1 (China low activation ferrite) steel was investigated. Mechanical properties of CLF-1 steels melted by vacuum induction melting (VIM, CS25 steel) and vacuum induction melting followed by consumable electrode remelting (VIM + ESR, CS350 steel) had been studied. The results indicated that the steels showed similar values of hardness and tensile strength, however, creep properties of CLF-1 steel were obviously improved by VIM + ESR process. M23C6 and M7C3 Carbides were precipitated in the CS25 steel, and M23C6 carbides were precipitated in CS350 steel after high-temperature tempering at 1013 K for 90 min. Creep properties of CS25 steel were shown to be dramatically deteriorated by the existence of rod M7C3 precipitates, which was due to W macrosegregation in the CS25 steel melted by VIM. M7C3 was replaced by M23C6 after ageing at 823 K for 5000 h.

  17. A model for the influence of microstructural defects on magnetic Barkhausen noise in plain steels

    International Nuclear Information System (INIS)

    This study presents a model of the microstructural defect influence on the magnetic Barkhausen noise in plain steels. The comparison of the theoretical and experimental results reveals an excellent agreement between them. We show that both model and experimental approach can be very useful, particularly, for the carbon content characterization in commercial steels

  18. Influence of phase transformation on the hardening of austenitic stainless steels

    International Nuclear Information System (INIS)

    The influence of phase transformation on the true stress-true strain curves of austenitic stainless steels was studied. This investigation was carried on one type of AISI 302 steel and one AISI 316 steel. The temperature range varied from -1960C to room temperature. A model for the workhardening of metaestable austenitic stainless steel is proposed. It was concluded that stress induced martensite epsilon may be responsible for the lowering of yield strength as well as the initial plateau on workhardening in these materials. (Author)

  19. The influence of furnace wall emissivity on steel charge heating

    Science.gov (United States)

    Švantner, Michal; Honnerová, Petra; Veselý, Zdeněk

    2016-01-01

    Radiation heat transfer is one of the most important heat transfer modes in high-temperature applications. It is a strongly non-linear process, which depends on the temperature and emissivity of heat exchange surfaces, their geometrical configuration and properties of the surrounding atmosphere. Heat exchange intensity between the surfaces depends mainly on their temperature differences. However, their emissivities influence significantly the radiation heat transfer process as well. Emissivity is a function of surface state or atmospheric chemical reactions, temperature and wavelengths. Because of these non-linearities, it is very complicated to evaluate such a real problem by numerical simulation, and experimental work seems to be the most reliable evaluation procedure. We applied special high-temperature coatings of different emissivities on furnace walls to evaluate the dependence between the furnace wall emissivity and steel charge heating. The emissivity analyses of the coatings used and emissivity measurement results in dependence on wavelength are presented in this paper. The dependence of the charge heating on the furnace wall emissivity, the importance of emissivity wavelength dependence and significant differences of the emissivity effect in electrical and gas heated furnaces are shown. The possible consequences and practical benefits are also discussed in this paper.

  20. Calculating Method for Influence of Material Flow on Energy Consumption in Steel Manufacturing Process

    Institute of Scientific and Technical Information of China (English)

    YU Qing-bo; LU Zhong-wu; CAI Jiu-ju

    2007-01-01

    From the viewpoint of systems energy conservation, the influences of material flow on its energy consumption in a steel manufacturing process is an important subject. The quantitative analysis of the relationship between material flow and the energy intensity is useful to save energy in steel industry. Based on the concept of standard material flow diagram, all possible situations of ferric material flow in steel manufacturing process are analyzed. The expressions of the influence of material flow deviated from standard material flow diagram on energy consumption are put forward.

  1. Influence of the storage conditions on prestressing steel relaxation losses

    Directory of Open Access Journals (Sweden)

    Suárez, F.

    2012-12-01

    Full Text Available Stress relaxation losses on active reinforcement have significant impact on prestressed concrete structures. This is why relaxation tests are carried out on prestressing steel wires and strands after being manufactured. Then, these materials are coiled and stored for a long-term period, sometimes in excess of one year. The influence of these operations, carried out after manufacturing, is usually neglected. Nevertheless, some manufacturers and contractors have noticed that, sometimes, when relaxation tests are carried out after a long-term storage, the relaxation losses found are higher than those measured immediately after manufacturing. In this work, lab tests are performed to check the influence of the coiling radius and the period of storage on the relaxation test. In addition to this, an analytical model is presented to predict the results of a relaxation test carried out on a wire coiled and stored for a long-term period. This model explains the evolution on the cross-sectional stress profile along the coiling-storing-uncoiling process, as well as the influence of the residual stresses on it.

    La pérdida de tensión por relajación en las armaduras activas afecta de forma importante a las estructuras de hormigón pretensado. Por ello se realizan ensayos de relajación de los alambres y cordones de pretensado tras su fabricación. Después, el material es enrollado y almacenado durante periodos que en ocasiones pueden superar el año de duración. Generalmente se desprecia la influencia que estas operaciones posteriores a la fabricación pueden tener sobre el material. Sin embargo, diversos fabricantes y suministradores han constatado experimentalmente que, en ocasiones, el material almacenado durante un periodo prolongado presenta pérdidas de relajación mayores que inmediatamente tras su fabricación. En este trabajo se realizan ensayos de laboratorio para comprobar la influencia que el radio de enrollamiento y el periodo de

  2. Influence of Characteristics on Bending Strength of Layered Steel Fiber Reinforced Concrete

    Institute of Scientific and Technical Information of China (English)

    DAI Shao-bin; SONG Ming-hai; HUANG Jun

    2005-01-01

    The influence of two main characteristics of steel fiber, the aspect ratio (Df) and volume fraction (pf), on the bending strength of Layered Steel Fiber Reinforced Concrete (LSFRC) is investigated by using orthogonal test. Via the variance analysis on the experimental results and trend analysis on the two characteristics, Df is found significantly related to the bending strength of LSFRC. The influence ratio is 63.3%. The bending strength of LSFRC increases if Df increases, makes better when Df reaches 100. ρf has ordinary influence on the bending strength of LSFRC. The influence ratio is 29.2%. Other characteristics, such as the shape of steel fiber and the mix proportion, have less influence. The best ρf contributing to the bending strength of LSFRC is 1.5 %. If pf is greater than 1.5 %, it has negative influence on the bending strength of LSFRC. So, pf makes a limited contribution to the bending strength of LSFRC.

  3. The role of acetogens in microbial influenced corrosion of steel

    Directory of Open Access Journals (Sweden)

    Jaspreet eMand

    2014-06-01

    Full Text Available Microbially-influenced corrosion (MIC of iron (Fe0 by sulfate reducing bacteria (SRB has been studied extensively. Through a mechanism, that is still poorly understood, electrons or hydrogen (H2 molecules are removed from the metal surface and used as electron donor for sulfate reduction. The resulting ferrous ions precipitate in part with the sulfide produced, forming characteristic black iron sulfide. Hydrogenotrophic methanogens can also contribute to MIC. Incubation of pipeline water samples, containing bicarbonate and some sulfate, in serum bottles with steel coupons and a headspace of 10% (vol/vol CO2 and 90% N2, indicated formation of acetate and methane. Incubation of these samples in serum bottles, containing medium with coupons and bicarbonate but no sulfate, also indicated that formation of acetate preceded the formation of methane. Microbial community analyses of these enrichments indicated the presence of Acetobacterium, as well we of hydrogenotrophic and acetotrophic methanogens. The formation of acetate by homoacetogens, such as Acetobacterium woodii from H2 (or Fe0 and CO2, is potentially important, because acetate is a required carbon source for many SRB growing with H2 and sulfate. A consortium of the SRB Desulfovibrio vulgaris Hildenborough and A. woodii was able to grow in defined medium with H2, CO2 and sulfate, because A. woodii provides the acetate, needed by D. vulgaris under these conditions. Likewise, general corrosion rates of metal coupons incubated with D. vulgaris in the presence of acetate or in the presence of A. woodii were higher than in the absence of acetate or A. woodii, respectively. An extended MIC model capturing these results is presented.

  4. The role of acetogens in microbially influenced corrosion of steel

    Science.gov (United States)

    Mand, Jaspreet; Park, Hyung Soo; Jack, Thomas R.; Voordouw, Gerrit

    2014-01-01

    Microbially influenced corrosion (MIC) of iron (Fe0) by sulfate-reducing bacteria (SRB) has been studied extensively. Through a mechanism, that is still poorly understood, electrons or hydrogen (H2) molecules are removed from the metal surface and used as electron donor for sulfate reduction. The resulting ferrous ions precipitate in part with the sulfide produced, forming characteristic black iron sulfide. Hydrogenotrophic methanogens can also contribute to MIC. Incubation of pipeline water samples, containing bicarbonate and some sulfate, in serum bottles with steel coupons and a headspace of 10% (vol/vol) CO2 and 90% N2, indicated formation of acetate and methane. Incubation of these samples in serum bottles, containing medium with coupons and bicarbonate but no sulfate, also indicated that formation of acetate preceded the formation of methane. Microbial community analyses of these enrichments indicated the presence of Acetobacterium, as well as of hydrogenotrophic and acetotrophic methanogens. The formation of acetate by homoacetogens, such as Acetobacterium woodii from H2 (or Fe0) and CO2, is potentially important, because acetate is a required carbon source for many SRB growing with H2 and sulfate. A consortium of the SRB Desulfovibrio vulgaris Hildenborough and A. woodii was able to grow in defined medium with H2, CO2, and sulfate, because A. woodii provides the acetate, needed by D. vulgaris under these conditions. Likewise, general corrosion rates of metal coupons incubated with D. vulgaris in the presence of acetate or in the presence of A. woodii were higher than in the absence of acetate or A. woodii, respectively. An extended MIC model capturing these results is presented. PMID:24917861

  5. Influence of Heat Treatments on the Corrosion Resistance of Medium -Carbon Steel using Sulfuric Spring Water

    Directory of Open Access Journals (Sweden)

    Ikhlas Basheer

    2013-04-01

    Full Text Available The corrosion is one of the important problems that may be occur to the parts of machinery and equipment after manufactured and when used as a result of exposure to corrosive media. Plain-carbon steel is considered as one of the most common minerals used in industrial applications. Some of heat treatments can have direct effect on the corrosion rate of steel by building up galvanic corrosion cells between its microscopic phases. Therefore, to adopt one of kinds of the plain-carbon steel and the most commonly used in industry to be study subject, that is medium carbon steel and took samples of this steel has been treated thermally in three methods which the normalising, annealing, and hardening .The corrosive media used in the research is Sulfuric Spring, it contains many chemical compounds to show its influence on the corrosion of steel. The weight loss method is used to determine corrosion rate and to compare between the results obtained, show that the greatest corrosion resistance of the annealed steel and the corrosion resistance of the hardened steel is the lowest while the corrosion  resistance of the normalised steel is in-between them.         Calcium carbonate was formed on the metal surface which acts as an isolating layer which decrease corrosion rate with time

  6. Cleavage crack propagation and arrest in a nuclear pressure vessel steel

    International Nuclear Information System (INIS)

    The integrity assessment of Reactor Pressure Vessels, mainly based on crack initiation, can be completed by studying crack propagation and arrest. Whereas engineering approaches do not take into account dynamic effects, these effects are important in unstable cleavage crack propagation, arrest and possible propagation re-initiation events. This study deals with physical mechanisms of cleavage crack propagation and numerical computations related to brittle fracture in the framework of local approach to fracture. Experiments were carried out on thin CT 25 specimens made of 16MND5 PWR vessel steel at five temperatures (-150 degrees C, -125 degrees C, -100 degrees C, -75 degrees C, -50 degrees C). Two kinds of crack path, straight or branching path, were observed. Branching cracks appear for the highest critical loadings at initiation, that increase the elastic stored energy and the effect of plasticity. The elastic-viscoplastic behavior of the ferritic steel was studied up to a strain rate of 104 s-1 and taken into account in the numerical simulations. The extended Finite Element Method (X-FEM) was used in CAST3M FE software to model crack propagation. Numerical computations combine a local non linear dynamic approach with a RKR type fracture stress criterion. The different physical micro-mechanisms, involved in cleavage fracture, were examined by the means of SEM fracture surface analyses at different temperatures and strain rates for the two kinds of crack path. The links of the critical fracture stress with both temperature and strain rate for straight crack path as well as analyses of branching crack phenomena were considered by the means of Scanning Electron Microscopy (SEM) fracture surface analyses, 3D quantitative optical microscopy and FE computations in order to aim at a robust physical justification of the propagation model which has already been developed at CEA in the frame of the B. Prabel PhD. (authors)

  7. The influence of molybdenum on stress corrosion in Ultra Low Carbon Steels with copper addition

    Directory of Open Access Journals (Sweden)

    M. Mazur

    2010-07-01

    Full Text Available The influence of molybdenum content on the process of stress corrosion of ultra-low carbon structural steels with the addition of copper HSLA (High Strength Low Alloy was analyzed. The study was conducted for steels after heat treatment consisting of quenching andfollowing tempering at 600°C and it was obtained microstructure of the tempered martensite laths with copper precipitates and the phaseLaves Fe2Mo type. It was found strong influence of Laves phase precipitate on the grain boundaries of retained austenite on rate anddevelopment of stress corrosion processes. The lowest corrosion resistance was obtained for W3 steel characterized by high contents ofmolybdenum (2.94% Mo which should be connected with the intensity precipitate processes of Fe2Mo phase. For steels W1 and W2which contents molybdenum equals 1.02% and 1.88%, respectively were obtained similar courses of corrosive cracking.

  8. The influence of aging on the intergranular corrosion of 22 chromium-5 nickel duplex stainless steel

    International Nuclear Information System (INIS)

    Duplex stainless steels are widely used in severe corrosion environments because of their good corrosion performance. This paper deals with the influence of aging treatments on the intergranular corrosion (IGC) resistance of a commercial duplex stainless steel, SAF 2205. Duplex stainless steel was given aging treatments in the range 773-1173 K for time periods ranging from 6 min to 100 h. Optical microscopy and XRD was carried out on the aged stainless steels for the microstructural study. The aged samples were evaluated for the IGC susceptibility with the ASTM standard practices. Potentiodynamic cyclic polarization studies were also carried out to investigate the influence of aging treatments on the passivity breakdown. The results indicate that the sigma phase gets precipitated and is responsible for grain boundary attack. (author)

  9. Influence of Subsurface Structure on the Linear Reciprocating Sliding Wear Behavior of Steels with Different Microstructures

    Science.gov (United States)

    Sharma, S.; Sangal, S.; Mondal, K.

    2014-12-01

    The present work investigates the influence of subsurface microstructure on the linear reciprocating sliding wear behavior of a number of steels with ferrite-pearlitic, pearlitic, bainitic, and martensitic microstructures under dry unlubricated condition. The change in the underlying microstructure with depth from worn-out surface of steel sample intimately relates to the associated hardness variation and wear volume. The present paper is not about comparison of wear resistance of steels with different structures; rather it is on mutual influence of wear and substructure for individual microstructure. Inherent toughness of the matrix and ability of microstructural components to get deformed under the reciprocating action of the ball decide the wear resistance of the steels. Bainite has good amount of stability to plastic deformation. Ferrite shows severe banding due to wear action. Work hardening renders pearlite to be wear resistant. Temperature rise and associated tempering of martensite are observed during wear.

  10. The influence of chemical composition on structure and mechanical properties of austenitic Cr-Ni steels

    Directory of Open Access Journals (Sweden)

    A. Kurc-Lisiecka

    2013-12-01

    Full Text Available Purpose: The aim of the paper is to investigated the influence of the chemical composition on the structure and mechanical properties of austenitic Cr-Ni steels. Special attention was put on the effect of solution heat treatment on mechanical properties of examined steels. Design/methodology/approach: The examinations of static tensile tests were conducted on ZWICK 100N5A. Hardness measurements were made by Vickers method. The X-ray analyzes were realized with the use of Dron 2.0 diffractometer equipped with the lamp of the cobalt anode. The metallographic observations were carried out on LEICA MEF 4A light microscope. Findings: Results shown that after solution heat treatment the values of strength properties (UTS, YS0.2 and hardness (HV of both investigated steels decrease and their elongation (EL increases. The X5CrNi18-8 steel in delivery state shown austenitic microstructure with twins and numerous non-metallic inclusions, while in steel X10CrNi18-8 revealed a austenitic microstructure with numerous slip bands in areas with deformation martensite α’. The examined steels after solution heat treatment followed by water-cooling has the structure of austenite. Research limitations/implications: To investigate in more detail the influence of chemical composition on structure and mechanical properties the examinations of substructure by TEM should be conducted. Originality/value: The relationship between the solution heat treatment, structure and mechanical properties of investigated steels was specified.

  11. Influence of Environmental Factors on the Volume Change of Blended Cement Containing Steel Slag

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In the condition of 20 ℃, 5% sulfate liquor curing, standard tap water curing and 50% RH curing-three different curing environments, the volume change of steel slag blended cement influenced by environmental factors was studied. With steel slag addition 10%, 30%, 50%, from 90 days to 356 days, the relationship of shrinkage and three different curing environments is: dry curing environment>tap water curing environment>sulfate curing environment. But, the sample shrinkage in 28 days has much difference with the curing environment, which has no obvious orderliness. The different effects on blended cement containing steel slag in different environmental factors were analyzed using SEM.

  12. Steel

    International Nuclear Information System (INIS)

    Composition of age hardening steel, % : Fe - (12.0-12.4) Cr - (2-2.7) Ni (0.5-0.6) Ti - (1.0-1.2) Mn - (0.03 - 0.04) C having high values of magnetoelastic internal friction and mechanical properties as well as an ability to operate under the conditions of alternating loadings are proposed. Damping properties of the steel permit to improve labour conditions. Data for the above steel on internal friction, impact strength and tensile properties are given

  13. Electrochemical Behavior of Steel Bar in Electrolytes:Influence ofpH Value and Cations

    Institute of Scientific and Technical Information of China (English)

    PU Qi; JIANG Linhua; CHU Hongqiang; XU Jinxia; XU Yi

    2011-01-01

    Steel bar corrosion on electrolytes and the influence of cation were investigated.Three electrolytes of Ca(OH)2,NaOH and KOH with pH levels of 12.5,11.5,10.5,9.5,8.5 were prepared,meanwhile,the methods of free corrosion potential and electrochemical impedance spectra (EIS) were used to evaluate the influence of cations on the depassivation of the steel bar in electrolytes.The experimental results indicate that the initial corrosion pH value of the steel bar is influenced by the cation in electrolyte and the influence ofK+ in electrolyte is the most remarkable,followed by Na+ and Ca2+.The initial corrosion pH values are 10.5 in KOH electrolyte,9.5 in NaOH electrolyte and lower than 8.5 in Ca(OH)2 electrolyte.

  14. Influence of silver additions to type 316 stainless steels on bacterial inhibition, mechanical properties, and corrosion resistance

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Tseng, I-Sheng; Møller, Per;

    2010-01-01

    techniques. The microstructure of these 316 stainless steels was examined, and the influences of silver additions to 316 stainless steels on bacterial inhibition, mechanical properties, and corrosion resistance were investigated. This study suggested that silver-bearing 316 stainless steels could be used in...

  15. Influence of sintering parameters on the properties of duplex stainless steel

    OpenAIRE

    L.A. Dobrzański; Z. Brytan; M. Actis Grande; M. Rosso

    2007-01-01

    Purpose: of this paper was to examine the influence of sintering parameters like time, temperature, atmosphereand gas pressure under cooling stage on the mechanical properties of duplex stainless steels.Design/methodology/approach: In presented study duplex stainless steels were obtained through powdermetallurgy starting from austenitic, martensitic base powders by controlled addition of alloying elements,such as Cr, Ni, Mo and Cu. In the studies behind the preparation of mixes, Schaeffler’s ...

  16. Properties of a Nb-V-Ti microalloyed steel influenced by cold rolling and annealing

    OpenAIRE

    M. Janošec; I. Schindler; J. Palát; L. Čížek; V. Vodárek; E. Místecký; Růžička, M. (Marek); L.A. Dobrzański; S. Rusz; P. Suchánek

    2007-01-01

    Purpose: was to investigate impact of cold forming and annealing on microstructural and mechanical propertiesof HSLA steel.Design/methodology/approach: Testing of Nb-V-Ti microalloyed strip steel was based on a combination ofcold rolling, recrystallization annealing, mechanical testing, metallography and TEM.Findings: It was confirmed that by a suitable combination of size of previous cold reduction size and parametersof the following annealing it is possible to influence considerably a compl...

  17. Influence of Bridge Deck Concrete Parameters on the Reinforcing Steel Corrosion

    OpenAIRE

    Balakumaran, Soundar Sriram G.

    2010-01-01

    Chloride induced corrosion of steel in concrete is one of the major forms of deterioration mechanisms found in reinforced concrete bridges. Early age corrosion damage reduces the lifespan of the bridges, which results in heavy economic losses. Research has been conducted to identify economic solutions for significantly delaying and/or preventing corrosion damage. Considering the amount of steel reinforcement used in bridge decks, the influence of as constructed parameters including clear spac...

  18. Influence of the Quenching Rate on the Spinodal Decomposition in a Duplex Stainless Steel

    OpenAIRE

    Hedin, M.; J. Massoud; Danoix, F.

    1996-01-01

    Cast duplex stainless steels are known to be susceptible to embrittlement after long term ageing at intermediate temperatures (300-400°C). This embrittlement is related to the spinodal decomposition that occurs in the ferrite phase. Steels of equivalent composition after undergoing the seemingly same heat treatment exhibit different microstructural and mechanical evolutions. One of the assumptions which explains this is based on the influence of the quenching rate. For this purpose, a set of ...

  19. Influence of bainite morphology on impact toughness of continuously cooled cementite free bainitic steels

    OpenAIRE

    García Caballero, Francisca; Roelofs, H; Hasler, St; Capdevila, Carlos; Chao, Jesús; Cornide, Juan

    2012-01-01

    The influence of bainite morphology on the impact toughness behaviour of continuously cooled cementite-free low carbon bainitic steels has been examined. In these steels, bainitic microstructures formed mainly by lath-like upper bainite, consisting of thin and long parallel ferrite laths, were shown to exhibit higher impact toughness values than those with a granular bainite, consisting of equiaxed ferrite structure and discrete island of marteniste/austenite (M/A) constituent....

  20. Influence of Ring Stiffeners on a Steel Cylindrical Shell

    Directory of Open Access Journals (Sweden)

    D. Lemák

    2005-01-01

    Full Text Available Shell structures are usually formed from concrete, steel and nowadays also from many others materials. Steel is typically used in the structures of chimneys, reservoirs, silos, pipelines, etc. Unlike concrete shells, steel shells are regularly stiffened with the help of longitudinal and/or ring stiffeners.The authors of this paper investigated steel cylindrical shells and their stiffening with the use of ring stiffeners. The more complete the stiffening, the more closely the shell will act to beam theory, and the calculations will be much easier. However, this would make realization of the structure more expensive and more laborious. The target of the study is to find the limits of ring stiffeners for cylindrical shells. Adequate stiffeners will eliminate semi-bending action of the shells in such way that the shell structures can be analyzed with the use of numerical models of the struts (e.g., by beam theory without significant divergences from reality. Recommendations are made for the design of ring stiffeners, especially for the distances between stiffeners and for their bending stiffness. 

  1. Influence of laser cutting on the fatigue limit of two high strength steels

    Energy Technology Data Exchange (ETDEWEB)

    Mateo, Antonio; Fargas, Gemma; Calvo, Jessica; Roa, Joan Josep [Univ. Politecnica de Catalunya, Barcelona (Spain). Dept. of Materials Science and Metallurgical Engineering

    2015-02-01

    Laser cutting is widely used in the metal industry, particularly when components of high strength steel sheets are produced. However, the roughness of cut edges produced by laser differs from that obtained by other methods, such as mechanical blanking, and this fact influences the fatigue performance. In the present investigation, specimens of two grades of high strength austenitic steels, i.e. AISI 301LN and TWIP17Mn, were cut by laser and tested in the high cycle fatigue regime to determine their corresponding fatigue limits. A series of fatigue specimens were tested without polishing and other series after a careful polishing of the cut edges, in order to assess the influence of the cut edges condition. Results indicate a significant influence of the edge roughness, more distinctive for AISI 301LN than for TWIP steel.

  2. INFLUENCE OF STEEL REINFORCEMENT ON THE BEHAVIOUR OF RCC SHELLS

    Directory of Open Access Journals (Sweden)

    S. S. ANGALEKAR,

    2011-02-01

    Full Text Available Unlike floor slabs of building, RCC shells require much less steel reinforcement to take care of tensile stresses developed. From the view point of ultimate behaviour of shell structures analysis considering presence of steel reinforcements is thought to be of importance. Paper deals with linear elastic behaviour and elasto-plastic behaviour of RCC shells subjected to uniform vertical surcharge over the top surface and the longitudinal thrust in the span direction. Besides varying the lengths of shells for a fixed section of shells three degree of reinforcements are considered. inite element analysis is performed employing 4 noded plate elements for conduction a parametric investigation in the form of various spans. Results of analysis reveal that so far as elastic behaviour is concerned the difference between concrete and RCC shell is negligibly small. However, elasto-plastic behaviour reveals that in general RCC shell has higher capacity compared with that of concrete shell.

  3. Influence of microstructure on the microbial corrosión behaviour of stainless steels

    OpenAIRE

    Moreno, Diego Alejandro; Ibars, José Ramón; Ranninger, Carlos

    2000-01-01

    Several stainless steels (Types UNS S30300, S30400, S30403, S31600, S31603 and S42000) with different microstructural characteristics have been used to study the influence of heat treatments on microbiologically influenced corrosion (MIC). Biocorrosion and accelerated electrochemical testing was performed in various microbiological media. Two species of sulphate-reducing bacteria (SRB) have been used in order to ascertain the influence of microstructure. The morphology of corrosion pits produ...

  4. EXPERIMENTAL RESEARCH REGARDING THE INFLUENCE OF CUTTING REGIME ON THE WEAR OF DRILLS AT STEEL PROCESSING

    Directory of Open Access Journals (Sweden)

    Leonard Marius CIUREZU GHERGHE

    2015-05-01

    Full Text Available This paper aims to highlight the influence of cutting regime on the wear drills at steel processing , in particular the processing of stainless steel X17CrNi16-2 SR EN 10088-4 DIN 17440. We are interested in wear of the drill at processing of this type of stainless steel , which has applicability in energy industry given the special characteristics of its. We want a maximum value of 0.2 mm for the wear of the drill, measurement and taking pictures are made using a microscope DigiMicro 2.0 and the software used is MicroCapture. Processing was done on machining center YMC YOUNG TECH 1050, and the tool used was 8 mm drill bit high speed steel.

  5. Influence of thermal treatment on structure and corrosion properties of high manganese triplex steels

    Directory of Open Access Journals (Sweden)

    S. Lasek

    2013-10-01

    Full Text Available In this paper corrosion properties of X70MnAl28-9 TRIPLEX steel were tested after hot rolling and subsequent aging at 500 °C for 6, 30 and 60 min. and at 600 °C for the same times. For comparison related steels(X100MnAl28-12, X70Mn22, C20 were also used. The microstructure wascharacterized by light microscopy, SEM, energy disperse Xray microanalysis. The corrosion behaviour of steels wasexamined by light and scanning electron microscopy, electrochemical techniques (potenciodynamic polarization method, linear polarization, using NaCl and H2SO4 water solutions, salt spray test and gravimetric method. Aging has relatively small influence on corrosion resistance of X70MnAl28-9 steel. The localized corrosion in relation to structure and phases is discussed and compared in terms of dissolution, pitting and changes inchemical composition.

  6. Influence of manganese and nickel on properties of low-carbon steels with 13% Cr

    International Nuclear Information System (INIS)

    Studied is the influence of manganese and nickel on mechanical properties and resistance-to-corrosion of the 13% content chromium steels containing 0.1-0.2%C. It is shown that manganese introduction results is the increase of strength characteristics of hardened steels because of delta-ferrite formation suppresion and solid solution strengthening. The delayed cooling during hardening permits to increase ductility and impact strength. Low-carbon 13% content chromium steels alloyed with nickel, molybdenum and aluminium have high heat resistance at temperatures up to 500 deg C due to the precipitation of intermetallics atlading. Chrome-manganese and chrome-nickel steels have a high resistance-to-corrosion in the hardened state in the neutral and weak-acid media

  7. INFLUENCE OF ABNORMAL AUSTENITE GRAIN GRAIN GROWTH IN QUENCHED ABNT 5135 STEEL

    Directory of Open Access Journals (Sweden)

    Camila de Brito Ferreira

    2015-03-01

    Full Text Available Grain size in the steels is a relevant aspect in quenching and tempering heat treatments. It is known that high austenitizing temperature and long time provide an increase in austenitic grain sizes. Likewise, after hardening of low alloy steel, the microstructure consists of martensite and a volume fraction of retained austenite. This paper evaluates the influence of austenite grain size on the volume fraction of retained austenite measured by metallographic analyses and X-ray diffraction. The Mi and Mf temperatures were calculated using an empirical equation and experimentally determined by differential thermal analysis. The mechanical behavior of the steel was evaluated by Vickers microhardness testing. Differently from other results published in the literature that steel hardenability increases with the austenite grain size, it was observed that the increase in austenite grain promotes greater volume fraction of retained austenite after water quenching.

  8. Rupture character of steels with ferrite-pearlite structure under influence of liquid metallic media

    International Nuclear Information System (INIS)

    Influence of liquid metal environment (gallium base alloy with melting point of 5 deg C) on mechanical properties and fracture mode was studied for ferritic-pearlitic steels with 0.03-0.8 % C under static and cyclic loading. Liquid metal medium was found to assist plastic deformation in a surface layer and to change fracture mode. It was revealed that the liquid of metal deteriorated steel properties in case of static loads but this effect weakened when passing from ferrite to pearlite. In ferritic steel under cycling loading the liquid metal affected so that shifted cracking resistance value to the region of lower stress intensity factors and promoted transition from intragranular fracture to intergranular one. Pearlitic steels behaved alike under cyclic loading both in liquid metal and in the air

  9. The influence of molybdenum on stress corrosion in Ultra Low Carbon Steels with copper addition

    OpenAIRE

    Mazur, M.; R. Bogucki; Pytel, S.

    2010-01-01

    The influence of molybdenum content on the process of stress corrosion of ultra-low carbon structural steels with the addition of copper HSLA (High Strength Low Alloy) was analyzed. The study was conducted for steels after heat treatment consisting of quenching andfollowing tempering at 600°C and it was obtained microstructure of the tempered martensite laths with copper precipitates and the phaseLaves Fe2Mo type. It was found strong influence of Laves phase precipitate on the grain boundarie...

  10. Influence of submerged entry nozzle clogging on the behavior of molten steel in continuously cast slab molds

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The influence of submerged entry nozzle clogging on the behavior of molten steel in continuously cast slab molds was studied using commercial code CFX4.3. The results indicate that clogging at the top part of the nozzle port not only increases the velocity of molten steel, but also enhances the wall shear stress, F number and heat flux. This clogging has the greatest effect on the behavior of molten steel. However, clogging at the top 1/3 of the nozzle only increases the velocity of molten steel and has little influence. Clogging at the bottom of the nozzle almost has no influence.

  11. Influence of technological parameters on the quality of cold rolled steels of stainless steels

    International Nuclear Information System (INIS)

    It is ascertain that an optimal loading of a cold-rolling shop should envisage the availability of at least 20% redundancy of heat treatment facilities. To ensure an optimal rollability of 12Kh18N9 steel, it is recommended to decrease the time interval between the passes and to increase the rolling rate in order to improve strip heating. Cold rolling efficiency and output of sheets of enhamed accuracy under the utmost loading of the shop can be enpanced via differentiated rate of bongitudinal that treatment of semifinished rolled products

  12. Influence of surface finish on the cleanability of stainless steel.

    Science.gov (United States)

    Frank, J F; Chmielewski, R

    2001-08-01

    Stainless steel for fabricating food processing equipment is available with various surface finishes. The objective of this research was to determine the effect of surface finish on cleanability. Nine samples of stainless steel, type 304, from various manufacturers including no finish (hot rolled and pickled), #4 finish, 2B mechanical polished, and electropolished were tested. Cleanability was assessed by using coupon samples soiled with either cultured milk inoculated with spores of Bacillus stearothermophilus or by growth of a Pseudomonas sp. biofilm. Samples were cleaned by immersion in a turbulent bath of 1.28% sodium hydroxide at 66 degrees C for 3 min followed by a sterile water rinse, neutralizing in 0.1% phosphoric acid for 30 s, rinsing in phosphate buffer, sanitizing in 100 ppm hypochlorite, neutralizing in sodium thiosulfate, and drying. To determine residual milk soil, coupon samples were covered with PM indicator agar and incubated for 25 h at 58 degrees C. Other coupons were subjected to an additional 10 soiling or cleaning cycles, and the residual protein was measured by using epifluorescent microscopy and image analysis. Results indicate that the spore count was more precise for measuring initial cleanability of the finished samples, and the protein residue determination was useful for determining the effect of repeated cleaning. Data on the removal of milk soil suggest that stainless steel should be purchased based on measures of surface defects rather than finish type. Surface defects, as determined using a surface roughness gauge, produced a correlation of 0.82 with spore counts. Data also indicated that biofilm was more difficult to remove than milk-based soil. PMID:11510656

  13. Influence of Rare Earths on Contact Fatigue of Rail Steels

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Rail/wheel contact fatigue of NbRE rail, Nb rail and U74 rail was investigated using contact fatigue tester. Microstructure and morphology as well as microhardness in the fatigue profiles were analyzed by scanning electron microscope and Vickers hardness respectively. The experimental results show that rare earths are able to delay the initiation and the propagation of fatigue cracks and postpone the surface shelling or spalling, even more, to reduce the crack propagation angle and the crack propagation depth in steady state as well as the plastic deformation area, and to improve work-hardening of the rail steel.

  14. The influence of hot-working processing on plasticity and structure of duplex steel

    Directory of Open Access Journals (Sweden)

    K. Radwanski

    2007-06-01

    Full Text Available Purpose: There are numerous branches of industry where the (α+γ duplex steels have not yet been sufficiently popularised due to problems with their forming, resulting from different properties of the both phases which make up the material. This paper analyses the influence of temperature and tension rate on the superplastic flow of the (α+γ duplex steel.Design/methodology/approach: Steel specimens were cold deformed with a 70% rolling reduction. After a solution head treatment (1350°C, the specimens were tensioned in temperatures ranging from 800 to 950°C at a rate of vr=15×10-3÷3×10-1mm/s in a 0.005Pa vacuum. Structural examination was carried out using light, scanning and transmission electron microscopy. A quantitative analysis of structural changes was performed using the „MetIlo” image analysis programme.Findings: This paper has shown the cooperation of structure reconstruction mechanisms during deformation of the investigated steel and attempet the changes that take place in the steel structure during superplastic flow.Practical implications: The research carried out enabled the understanding of the phenomena taking place during deformation and annealing of the investigated alloy. The results will constitute the basis for modelling the structural changes.Originality/value: The results will be used to design the basis for a thermo-mechanical processing technology via rolling and inter-operational annealing of the investigated steel.

  15. Influence of delta ferrite on mechanical and creep properties of steel P92

    Energy Technology Data Exchange (ETDEWEB)

    Mohyla, Petr [VSB - Technical Univ. of Ostrava (Czech Republic). Faculty of Mechanical Engineering; Kubon, Zdenek [Material and Metallurgical Research Ltd., Ostrava (Czech Republic)

    2010-07-01

    This article presents some new results obtained during research of chromium modified steel P92. This steel is considered the best modified 9-12% Cr steel for the construction of modern power plants with ultra-super-critical steam parameters. High creep rupture strength of steel P92 is characterized by its chemical composition and by microstructure as well. Optimal microstructure of steel P92 is ideally composed of homogeneous martensite and fine dispersion of secondary particles. During the research program one P92 heat with an occurrence of about 20% delta ferrite was produced. The article describes the microstructure of the heat in various modes of heat treatment, as well as the results of mechanical properties tests at room temperature and also creep test results. The results are confronted with properties of other heats that have no delta ferrite. The relevance is on the significant difference while comparing of creep test results. The comparison of results brings conclusions, defining influence of delta ferrite on mechanical and creep properties of P92 steel. (orig.)

  16. The influence of sintering time on the properties of PM duplex stainless steel

    Directory of Open Access Journals (Sweden)

    Z. Brytan

    2009-12-01

    Full Text Available Purpose: The purpose of this paper is to analyse the effect of sintering time on the pore morphology, microstructural changes, tensile properties and corrosion resistance of vacuum sintered duplex stainless steel.Design/methodology/approach: In presented study PM duplex stainless steels were obtained through mixing base ferritic stainless steel powder with controlled addition of elemental alloying powders and then sintered in a vacuum furnace with argon backfilling at 1250°C for different time periods. Produced materials were studied by LOM/SEM metallography and the pore morphology was characterized. The mechanical properties were studied in tensile, hardness and Charpy impact tests. The corrosion resistance was evaluated by means of salt spray test and immersion in sulfuric acid.Findings: Prolongation of sintering time influenced on increase of density thus on the mechanical properties and microstructure balance.Practical implications: Mechanical properties of obtained PM duplex stainless steels are very promising, especially with the aim of extending their field of possible applications.Originality/value: The possibility of obtaining balanced austenitic-ferritic microstructure of stainless steel using elemental powders added to a stainless steel base powder. The vacuum sintering of such powder mixture results in good microstructural homogeneity.

  17. Influence of oil and water media on fretting behaviour of AISI 52100 steel rubbing against AISI 1045 steel

    Institute of Scientific and Technical Information of China (English)

    REN Ping-di; CHEN Guang-xiong; ZHU Min-hao; ZHOU Zhong-rong

    2004-01-01

    A series of fretting test were carried out using a DELTA PLINT testing system to study the influence of hydraulic oil and water on fretting behaviour of AISI 52100 steel rubbing against AISI 1045 steel. The test result shows that media hydraulic oil and water have a distinct influence on fretting behaviour of the tested materials. Medium water can lead to shifting of the partial slip regime in the fretting map from a larger displacement amplitude toward a smaller one and enlargement of the mixed slip regime, in comparison with that in ambient atmosphere. While medium hydraulic oil can result in shifting of the partial slip regime from a smaller displacement amplitude toward a larger one. In the gross slip regime, hydraulic oil and water play a positive role as lubrication media. They can clearly decrease the fretting friction coefficient between AISI 52100 and AISI 1045. The test result also demonstrates that this lubrication effect will get better with increasing displacement amplitude and that hydraulic oil is better than water for lubrication. SEM observation of the wear scars displays that the fretting wear mainly results from abrasive wear and delamination of the fretted materials when using these two kinds of substances as lubrication media.

  18. Influence of heating rate on sorbitic transformation temperature of tempering C45 steel

    Directory of Open Access Journals (Sweden)

    A. Kulawik

    2011-04-01

    Full Text Available In this paper the analysis of speed heating influence on sorbitic transormation temperature of tempering C45 steel is presented. On thebasis of dilatometric research, functions associating heating time with initial and final temperature of sorbitic transformation have beendetermined as well as the size structural (γ and thermal (α expansion coefficients of quenching and tempering structures have beenestimated.

  19. Corrosion of low alloy steels in natural seawater. Influence of alloying elements and bacteria

    International Nuclear Information System (INIS)

    Metallic infrastructures immersed in natural seawater are exposed to important corrosion phenomena, sometimes characterised as microbiologically influenced corrosion. The presence of alloying elements in low alloy steels could present a corrosion resistance improvement of the structures. In this context, tests are performed with commercial steel grades, from 0,05 wt pc Cr to 11,5 wt pc Cr. They consist in 'on site' immersion in natural seawater on the one hand, and in laboratory tests with immersion in media enriched with marine sulphide-producing bacteria on the other hand. Gravimetric, microbiological, electrochemical measurements and corrosion product analyses are carried out and show that corrosion phenomenon is composed of several stages. A preliminary step is the reduction of the corrosion kinetics and is correlated with the presence of sessile sulphide-producing bacteria and an important formation of sulphur-containing species. This phase is shorter when the alloying element content of the steel increases. This phase is probably followed by an increase of corrosion, appearing clearly after an 8-month immersion in natural seawater for some of the grade steels. Chromium and molybdenum show at the same time a beneficial influence to generalised corrosion resistance and a toxic effect on sulphide-producing bacteria. This multidisciplinary study reflects the complexity of the interactions between bacteria and steels; sulphide-producing bacteria seem to be involved in corrosion processes in natural seawater and complementary studies would have to clarify occurring mechanisms. (author)

  20. Influence of different thermal treatment in sintered steels base molybdenum

    International Nuclear Information System (INIS)

    Prealloyed steel powders with different amount of Mo-Cu-Ni-C were compacted at 700 MPa and sintered at 1120 degree centigrade in 95% N2 -5% H2. After sinterizing, these materials were treated by carburizing. For materials characterization radial crushing strength were preformed, density was calculated and a complete study of fracture surfaces was carried out using scanning electron microscopy. The results of radial crushing strength show that resistance after carburizing is higher than in sintered materials. The fracture surfaces give an idea of materials briteless and the treatment depth. In sintered materials, a ductil surface was observed, with the characteristic dimples. The fracture surfaces after different treatments show brittleness in the outer zone, while appears a mix of ductil and briteless fracture. (Author) 7 refs

  1. Influence of coolant motion on structure of hardened steel element

    Directory of Open Access Journals (Sweden)

    A. Kulawik

    2008-08-01

    Full Text Available Presented paper is focused on volumetric hardening process using liquid low melting point metal as a coolant. Effect of convective motion of the coolant on material structure after hardening is investigated. Comparison with results obtained for model neglecting motion of liquid is executed. Mathematical and numerical model based on Finite Element Metod is described. Characteristic Based Split (CBS method is used to uncouple velocities and pressure and finally to solve Navier-Stokes equation. Petrov-Galerkin formulation is employed to stabilize convective term in heat transport equation. Phase transformations model is created on the basis of Johnson-Mehl and Avrami laws. Continuous cooling diagram (CTPc for C45 steel is exploited in presented model of phase transformations. Temporary temperatures, phases participation, thermal and structural strains in hardening element and coolant velocities are shown and discussed.

  2. Influence of ultrasonic cavitation on passive film of stainless steel.

    Science.gov (United States)

    Wang, Bao-Cheng; Zhu, Jin-hua

    2008-03-01

    The electrochemical behaviors of passive film of stainless steel 0Cr13Ni5Mo under the condition of static state (quiescence) and ultrasonic cavitation in the HCl solution have been studied by means of polarization curve, electrochemical impedance spectroscopy (EIS) and capacitance potential measurement. The results indicate that the passive film shows a multi layer structure distribution, and presents a p-type semiconductor property under the condition of quiescence. The stability of passive film decreases, the semiconducting property changes to an n-type semiconductor in the presence of cavitation. The amount of transition electrons from valence band because of cavitation is related to the height of Fermi level of passive film semiconductor. PMID:17584517

  3. The influence of the residual copper on the pipes steel hot plasticity according to environmental requirements

    OpenAIRE

    Rusănescu C.O.; Rusănescu M.

    2013-01-01

    Considering the importance of gaseous and/or liquid fuels impact on the environment, the resistance of pipelines at hot plastic deformation is important. Therefore, in order to avoid or reduce any adverse impact on the environment, the influence of residual copper on hot deformability of steel pipes was investigated in this paper. The negative copper influence was experimentally proved using torsion deformation at temperatures above 1000o, under the air and...

  4. Influence of Surface Treatment on the Corrosion Resistance of Stainless Steel in Simulated Human Body Environment

    Institute of Scientific and Technical Information of China (English)

    Esmaeil Jafari; Mohammad Jafar Hadianfard

    2009-01-01

    In the present research, the influence of chromium enrichment by surface treatment on corrosion resistance of type 316L stainless steel in body environment was investigated. For this study, weight loss test during 18 months, cyclic and liner polarization tests before and after surface treatment and metallography by electron and light microscopy were used to evaluate the effectiveness of the proposed method. In addition, X-ray photoelectron spectroscopy (XPS) method was used to determine the chromium concentration in the surface layer after surface treatment. Results show that the surface treatment has improved corrosion resistance of the type 316L stainless steel in body environment.

  5. The Influence of Applied Stress Ratio on Fatigue Strength of TiN-coated Carbon Steel

    OpenAIRE

    Shiozawa, Kazuaki; Nishino, Seiichi; Handa, Keiichi

    1992-01-01

    The influence of applied stress ratio on the fatigue strength of carbon steel coated with TiN was studied on the basis of measurement of crack initiation with the D. C. potential method. Fatigue tests were performed under the stress ratios of R=0 and -1 in air using the round notched specimens of O.37%C steel, JIS S35C, normalized and coated with TiN by physical vapor deposition (PVD) and chemical vapor deposition (CVD). From the experimental results, increase in fatigue strength was observed...

  6. Influence of Partial Replacement of Nickel by Nitrogen on Microstructure and Mechanical Properties of Austenitic Stainless Steel

    Directory of Open Access Journals (Sweden)

    A. Ahmed

    2011-01-01

    Furthermore, the produced forged steels were subjected to solution treatment at different temperatures. The microstructure of produced stainless steels was observed. The X-ray diffractmeter and Mossbauer effect spectroscopy were used to follow the phase change in reference and modified steels after different heat treatment temperatures. The influence of grain-size, soluble, and insoluble nitrogen on tensile strength and hardness was investigated. The major phase in the modified steel has a fcc structure similar to the reference one, but with finer grains and more expanded lattice. The yield strength and hardness of the nitrogen-modified stainless steel are higher than the reference steel. On the other hand, the increase of nitrogen content deteriorates the steel ductility.

  7. Influence of Boron on transformation behavior during continuous cooling of low alloyed steels

    Energy Technology Data Exchange (ETDEWEB)

    Terzic, A., E-mail: Adnan.Terzic@imf.tu-freiberg.de [Technische Universität Bergakademie Freiberg, Institute of Metal Forming, Bernhard-von-Cotta-Str. 4, 09596 Freiberg (Germany); Calcagnotto, M. [Salzgitter Mannesmann Forschung GmbH, Eisenhüttenstr. 99, 38239 Salzgitter (Germany); Guk, S. [Technische Universität Bergakademie Freiberg, Institute of Metal Forming, Bernhard-von-Cotta-Str. 4, 09596 Freiberg (Germany); Schulz, T. [Salzgitter Mannesmann Forschung GmbH, Eisenhüttenstr. 99, 38239 Salzgitter (Germany); Kawalla, R. [Technische Universität Bergakademie Freiberg, Institute of Metal Forming, Bernhard-von-Cotta-Str. 4, 09596 Freiberg (Germany)

    2013-11-01

    Abstracts: The phase transformation behavior during continuous cooling of low-carbon (LC) Boron-treated steels was studied. Furthermore, the influence of combining Boron with Nb or Ti or V on transformation kinetics was investigated. Additions of Boron to LC steels have a strong influence on the ferrite transformation. By adding 30 ppm Boron to a Boron-free reference alloy the suppressing effect on the ferrite transformation is most pronounced, whereas 10 ppm Boron has almost no effect and 50 ppm Boron the same effect as 30 ppm Boron. Thereby the critical Boron concentration for transformation kinetics in this alloying concept is 30 ppm. The combination of Boron with Ti shifts the phase fields to shorter times and increase the ferrite start temperature, whereas the combination of B+V and B+Nb only affects the ferrite start temperature. Hardness values are mostly influenced by the presence of Boron and strongly depend on the cooling rate.

  8. Modelling the influence of steel fibres on the electrical resistivity of cementitious composites

    DEFF Research Database (Denmark)

    Solgaard, Anders Ole Stubbe; Michel, Alexander; Stang, Henrik;

    2009-01-01

    the overall resistivity of the material and thereby the corrosion rate of the embedded reinforcement. To the knowledge of the authors, only preliminary studies have been made on the influence of corrosion of the reinforcement bars from the addition of the electrical conductive steel fibres. Thus the present......One of the governing factors on the corrosion of embedded reinforcement is the electrical resistivity of the concrete. The combination of steel fibres and conventional reinforcement bars has been used in a number of structures. However, the addition of electrical con-ductive fibres might influence...... work concerns the electrical resistivity of cementitious composites and some of the parameters influencing it in order to get a more thorough understanding of the factors governing the overall resistivity. The basis of the present study is an experimental investigation of the electrical resistivity...

  9. Austenite steel transformations under the influence of fatigue loading

    Directory of Open Access Journals (Sweden)

    D. Skibicki

    2008-10-01

    Full Text Available Behavior of materials and structures in fatigue non-proportional loading conditions, characterized by the principal axes rotation during fatigue cycles, is an important issue because of its impact on fatigue properties. The article presents results of an analysis ofmicrostructural steel X5CrNi18-10, subjected to proportional fatigue loadings: torsion and push-pull, as well as non-proportional ones.Variability of the principal axes positions of non-proportional loadings was obtained by using a loading program with alternately realized torsion and tension-compression blocks. The work includes an analysis of one-phase microstructure and microhardness tests of fatigue samples were carried out. The cyclic loading value accepted for the tests caused an martensite transformation induced by plastic strain and occurrence of slip bands in the grains of austenite. A comparative analysis revealed differences in the transformation intensity, depending on the type of applied loading and on the degree of its non-proportionality.

  10. Green rusts in electrochemical and microbially influenced corrosion of steel

    Science.gov (United States)

    Refait, Philippe; Abdelmoula, Mustapha; Génin, Jean-Marie R.; Sabot, René

    2006-06-01

    Green rusts have been identified as corrosion products of steel in neutral or slightly alkaline aqueous media. They were mainly observed in carbonated media, where the carbonated green rust is obtained, and in seawater, where the sulphated variety is obtained. In the first case, the formation of the carbonated green rust competes with that of siderite FeCO 3. It is favoured when the dissolution of iron is accompanied by the reduction of dissolved oxygen and the formation of OH - ions. In the second case, the formation of the sulphated variety competes with that of the chlorinated variety. The sulphated green rust is obtained since the layered structure of green rusts is characterised by a strong affinity for divalent anions. Finally, the oxidation of green rusts leads to the various constituents of 'common' rust. The conditions favouring the formation of a ferric compound keeping the crystal structure of green rusts is discussed. To cite this article: P. Refait et al., C. R. Geoscience 338 (2006).

  11. The influence of hydrogen on the mechanical properties and structure of a stable 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Iyer, K.J.L. (Dept. of Metallurgical Engineering, Indian Inst. of Technology, Madras (India))

    1989-01-01

    Experiments have been carried out to study the influence of hydrogen on the mechanical properties of a stable 304 stainless steel by using a procedure for hydrogen charging which did not cause the irreversible damage of the steel which invariably accompanies electrolytic charging. The steel was charged by soaking at 1050{degree}C in a mixture of very pure argon and hydrogen mixture (97% argon, and 3% hydrogen) at a pressure slightly above atmospheric and continuously sending the sparks into the mixture for a long time. In the stainless steel investigated, hydrogen raises the 0.2% yield strenght; there is a small decrease in the tensile strength and a substantial decrease in elongation. The hydrogen charged specimens showed a predominantly ductile fracture. Ageing resulted in substantial recovery of the tensile properties. Loss of ductility was pronounced at low cross head speeds. The susceptibility of austenitic stainless steel to hydrogen embrittlement decreases with increasing temperature and vanishes at elevated temperature. It appears that hydrogen has little effect on the mechanical properties in compression. Bend testing of hydrogen charged material did not show any delayed failure even after prolonged loading. The elastic modulus, hardness and impact properties were not signifiancy affected. The effect of hydrogen on the mechanical properties of 304 austenitic stainless steel is consistent with the dislocation transport model of hydrogen embrittlement. The results also demonstrate that stable stainless steel is embrittled by hydrogen even though there is no evidence of phase transformation from X-ray diffraction, optical or electron microscopy. 11 refs., 7 figs.

  12. Influence of heat input on weld bead geometry using duplex stainless steel wire electrode on low alloy steel specimens

    Directory of Open Access Journals (Sweden)

    Ajit Mondal

    2016-12-01

    Full Text Available Gas metal arc welding cladding becomes a popular surfacing technique in many modern industries as it enhances effectively corrosion resistance property and wear resistance property of structural members. Quality of weld cladding may be enhanced by controlling process parameters. If bead formation is found acceptable, cladding is also expected to be good. Weld bead characteristics are often assessed by bead geometry, and it is mainly influenced by heat input. In this paper, duplex stainless steel E2209 T01 is deposited on E250 low alloy steel specimens with 100% CO2 gas as shielding medium with different heats. Weld bead width, height of reinforcement and depth of penetration are measured. Regression analysis is done on the basis of experimental data. Results reveal that within the range of bead-on-plate welding experiments done, parameters of welding geometry are on the whole linearly related with heat input. A condition corresponding to 0.744 kJ/mm heat input is recommended to be used for weld cladding in practice.

  13. The influence of sub-temperature quenching temperature on microstructure and properties of 60Si2Mn steel

    OpenAIRE

    Li, Anming; Hu, Mengjuan

    2012-01-01

    Influence of sub-temperature quenching temperature on the tensile strength, hardness and toughness of 60Si2Mn steel was studied, and the ferrite content, austenite grain size and martensite morphology of the microstructure of this steel after sub-temperature quenching were analyzed. The results show that duplex microstructure of martensite and ferrite is obtained by sub-temperature quenching of 60Si2Mn steel. The ferrite content decreases with the quenching temperature increasing. The strengt...

  14. Vpliv popravil na mikrostrukturo zvarov jekla Niomol 490K: Influence of repairs on microstructure of steel Niomol 490K welds:

    OpenAIRE

    Celin, Roman; Tušek, Janez

    2000-01-01

    During the erection of steel assemblies, repairs of not allowable defects in welds are necessary. Very demanding for welding are the HSLA steels. Investigations were performed to establish the influence of repairs of welds on the microstructure and the heat affected zone on the steel Niomol 490K. The microstructure of six joints prepared using different welding parameters was investigated in SEM. Results are presented in this paper. Pri varjenju jeklenih konstrukcij so pogosta popravila zv...

  15. Cleavage dynamic propagation analysis in a nuclear reactor pressure vessel steel using a high-speed camera

    International Nuclear Information System (INIS)

    Initiation stage of cracks is considered as a key issue, but more and more component integrity analyses investigate the crack propagation and arrest possibility. This study deals with physical mechanisms of cleavage crack propagation and numerical computations related to brittle fracture. Dynamic effects, involved in unstable cleavage crack propagation, have to be taken into account to properly depict brittle crack propagation, arrest and possible propagation re-initiation events. Experiments were carried out on thin CT specimens made of 16MND5 PWR vessel steel at five temperatures (-150 degrees C, -125 degrees C, -100 degrees C, -75 degrees C, -50 degrees C). In addition to standard crack gages, an innovative experimental technique has been used to determine crack propagation. By the means of developments on the experimental protocol (improvements of isolation and airtightness of the thermal chamber, optimization of the experimental protocol to eliminate ice in the thermal chamber and in order to have a good acquisition quality), use of a high speed framing camera was made possible to measure crack propagation on a CT mirror polished surface. This optical device, combined with this optimized experimental process, has allowed the study of straight and branching crack paths with high accuracy. The framing camera (520 000 fps up to 1 100 000 fps) has allowed to have a very accurate estimation of crack speed even up to 1000 m.s-1 and also to detect some phases of crack branching during propagation and phases of arrest-re-initiation. Numerical computations, based on X-FEM and combining a local non linear dynamic approach with a RKR type fracture stress criterion, have been performed to depict experimental crack behavior. This paper describes this innovative experimentation and the interpretation by FE calculations and SEM observations associated with quantitative 3D optical microscopy. (authors)

  16. Influence of heat treatment conditions on microstructures and mechanical properties of ferritic-martensitic ODS steel

    International Nuclear Information System (INIS)

    To develop an advanced ODS steel for core structural materials for next generation nuclear reactor system applications, it is important to optimize its heat treatment conditions to improve the high temperature strength and radiation resistance. This study investigates effects of heat treatment conditions on microstructures and mechanical properties of FM ODS steel. For this, 10Cr -1Mo FM ODS steel was prepared by mechanical alloying (MA), hot isostatic pressing (HIP), and hot extrusion process. Hardness measurements were carried out after heat treatments to evaluate the influences of heat treatments on the mechanical properties. The microstructures were observed using SEM, electron back-scatter diffraction (EBSD) and transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS). This study investigated the effects of heat treatment conditions on microstructures and mechanical properties of FM ODS steel. The FM ODS steels were fabricated by the MA, HIP and hot-extrusion processes. The optimized heat treatment condition for 10Cr-1Mo FM ODS was determined to enhance the mechanical property

  17. Influence of Mo on hot rolling textures of Fe-3%Si grain-oriented silicon steels

    International Nuclear Information System (INIS)

    In the production of high-induction grain-oriented silicon steels (Hi-B), in order to achieve a perfect secondary recrystallization structure with a sharp [110] texture, prior to hot rolling, the continuously cast slabs must be heated at over 1,350 C, which not only consumes a large amount of energy, but also pollutes the furnace bottom due to the melting of the slab surface oxide, and as a result, makes it necessary to clear the furnace bottom regularly. Hence, the decrease of the slab heating temperature plays a key role in increasing the production and decreasing the production cost of Hi-B steels. Very recently, it was found by researchers in Wuhan Iron and Steel Company that by adding a small amount of Mo to Hi-B steels, the slab heating temperatures can be reduced, and the magnetic properties become more stable. The object of this work is to utilize the crystallite orientation function (ODF) technique to study systematically the influence of Mo on the hot rolling texture of Hi-B steels

  18. Influence of Vanadium and Cast Temperature on Nitrogen Solubility of Stainless Steel

    Directory of Open Access Journals (Sweden)

    Saeed Ghali

    2014-01-01

    Full Text Available Three stainless steel grades with different vanadium content were produced in open induction furnace. The base chemical composition of investigated stainless steel has contained 18.48–18.75% Cr, 5.17–5.62% Mn, 2.47–2.58% Mo, and 6.39–6.64% Ni. The vanadium contents of the three stainless steel grades were 0.009%, 0.112%, and 0.189%. The proposed stainless steels were casted at temperatures 1753 K and 1833 K. The nitrogen contents were determined for the produced steel grades at every cast temperature. The determined nitrogen contents were compared with those calculated from the developed equation of Grigorenko and Pomarin. The influence of cast temperature and vanadium content on nitrogen solubility was investigated. Interpretation between experimental and calculated nitrogen content was carried out. Increasing vanadium content and decreasing cast temperature were found to have positive significant effect on the nitrogen solubility. There were great deviations between experimental results and those calculated by Grigorenko and Pomarin equation.

  19. Influence of delta ferrite on corrosion susceptibility of AISI 304 austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Lawrence O. Osoba

    2016-12-01

    Full Text Available In the current study, the influence of delta (δ ferrite on the corrosion susceptibility of AISI 304 austenitic stainless steel was evaluated in 1Molar concentration of sulphuric acid (H2SO4 and 1Molar concentration of sodium chloride (NaCl. The study was performed at ambient temperature using electrochemical technique—Tafel plots to evaluate the corrosive tendencies of the austenitic stainless steel sample. The as-received (stainless steel specimen and 60% cold-worked (stainless steel specimens were isothermally annealed at 1,100°C for 2 h and 1 h, respectively, and quenched in water. The results obtained show that the heat-treated specimen and the 60% cold-worked plus heat-treated specimen exhibited higher corrosion susceptibility than the as-received specimen, which invariably contained the highest fraction of δ ferrite particles. The finding shows that the presence of δ ferrite, in which chromium (Cr, the main corrosion inhibitor segregates, does not degrade and or reduces the resistance to aqueous corrosion of the austenitic stainless steel material.

  20. The influence of drawing speed on properties of TRIP steel wires

    Directory of Open Access Journals (Sweden)

    M. Suliga

    2008-02-01

    Full Text Available Purpose: The aim of this paper is to determine the influence of drawing speed of TRIP steel wires on their properties.Design/methodology/approach: The heat treatment of steel containing 0.09 % carbon, 1.57 % manganese and 0.9 % silicon allows to obtain TRIP type structure. The wires were drawn with different drawing speed. After drawing mechanical properties of wires were determined by the tensile test. In this work also FEM modelling was done.Findings: The analysis of changes of mechanical properties after particular drawings stages was carried out. The increase of drawing speed cause the increase of strength properties and decreasing of plasticity properties of wires. It was shown that increase of drawing speed causes increase of: temperature, non-dilatation strain and internal stresses.Research limitations/implications: Continuation of the investigations with the use of scanning and transmission electron microscopy makes it possible to explain the changes properties of drawn wires by analyses of structure of drawn wires.Practical implications: TRIP steel wires, which have good mechanical properties and are dependent on drawing speed, can be used for production of connecting elements.Originality/value: For the first time there was shown the influence of drawing speed on properties of TRIP steel wires.

  1. Heat treatment temperature influence on ASTM A890 GR 6A super duplex stainless steel microstructure

    International Nuclear Information System (INIS)

    Duplex and super duplex stainless steels are ferrous alloys with up to 26% chromium, 8% nickel, 5% molybdenum and 0.3% nitrogen, which are largely used in applications in media containing ions from the halogen family, mainly the chloride ion (Cl-). The emergence of this material aimed at substituting Copper-Nickel alloys (Cupro-Nickel) that despite presenting good corrosion resistance, has mechanical properties quite inferior to steel properties. The metallurgy of duplex and super duplex stainless steel is complex due to high sensitiveness to sigma phase precipitation that becomes apparent, due to the temperatures they are exposed on cooling from solidification as well as from heat treatment processes. The objective of this study was to verify the influence of heat treating temperatures on the microstructure and hardness of ASTM A890/A890M Gr 6A super duplex stainless steel type. Microstructure control is of extreme importance for castings, as the chemical composition and cooling during solidification inevitably provide conditions for precipitation of sigma phase. Higher hardness in these materials is directly associated to high sigma phase concentration in the microstructure, precipitated in the ferrite/austenite interface. While heat treatment temperature during solution treatment increases, the sigma phase content in the microstructure decreases and consequently, the material hardness diminishes. When the sigma phase was completely dissolved by the heat treatment, the material hardness was influenced only due to ferrite and austenite contents in the microstructure

  2. The influence of chemical constitution on abrasive wear of alloy cast steel Cr, Mo, V, Cu, Ni type

    International Nuclear Information System (INIS)

    In the work were presented some elements of a wide research programme of the influence of alloying element contents such as Cr, Mo, V on the abrasive wear of hot working cast steel. The dependence between the mass decrement quantity and the element contents on cast steel structure were shown. (author)

  3. The role of acetogens in microbially influenced corrosion of steel

    OpenAIRE

    Jaspreet eMand; Hyung Soo ePark; Jack, Thomas R.; Gerrit eVoordouw

    2014-01-01

    Microbially influenced corrosion (MIC) of iron (Fe0) by sulfate-reducing bacteria (SRB) has been studied extensively. Through a mechanism, that is still poorly understood, electrons or hydrogen (H2) molecules are removed from the metal surface and used as electron donor for sulfate reduction. The resulting ferrous ions precipitate in part with the sulfide produced, forming characteristic black iron sulfide. Hydrogenotrophic methanogens can also contribute to MIC. Incubation of pipeline water ...

  4. Influence of sintering parameters on the properties of duplex stainless steel

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2007-01-01

    Full Text Available Purpose: of this paper was to examine the influence of sintering parameters like time, temperature, atmosphereand gas pressure under cooling stage on the mechanical properties of duplex stainless steels.Design/methodology/approach: In presented study duplex stainless steels were obtained through powdermetallurgy starting from austenitic, martensitic base powders by controlled addition of alloying elements,such as Cr, Ni, Mo and Cu. In the studies behind the preparation of mixes, Schaeffler’s diagram was takeninto consideration. Prepared mixes have been compacted at 800 MPa and sintered in a vacuum furnace withargon backfilling at temperatures from 1200°C to 1285°C for 0.5, 1 and 2 h. After sintering different coolingcycles were applied using nitrogen under pressure from 0.6 MPa to 0.002MPa in argon atmosphere. Producedduplex stainless steels have been studied by scanning and optical microscopy and EDS chemical analysis ofmicrostructure components. Mechanical properties have been studied through tensile test.Findings: Mechanical properties of sintered stainless steels are strictly connected with the density and the poremorphology present in the microstructure too and especially of cooling rate directly from sintering temperature.The lowest cooling rate - applied gas pressure, the mechanical properties decrease due to precipitation of sigmaphase. Mechanical properties of studied steels depends on austenite/ferrite ratio in the microstructure andelements partitioning between phases too.Research limitations/implications: Applied fast cooling rate seems to be a good compromise for mechanicalproperties and obtained microstructures, nevertheless further tests should be carried out in order to examine itinfluence on corrosion properties.Originality/value: The use of elemental powders added to a stainless steel base showed its potentialities, interms of fair compressibility and final sintered density. In addition a good microstructural homogeneity

  5. Influence of hot-working conditions on a structure of high-manganese austenitic steels

    Directory of Open Access Journals (Sweden)

    A. Grajcar

    2008-08-01

    Full Text Available Purpose: The aim of the paper is to determine the influence of hot deformation conditions on σ-ε curves and structure changes of new-developed high-manganese austenitic steels.Design/methodology/approach: The force-energetic parameters of hot-working were determined in hot-compression tests performed in a temperature range of 850 to 1050°C by the use of the Gleeble 3800 thermomechanical simulator. Evaluation of processes controlling work hardening at 850°C were identified by microstructure observations of the specimens water-quenched after plastic deformation to a true strain equal 0.22, 0.51 and 0.92.Findings: At initial state the steel containing 3% of Si and Al possesses homogeneous austenite structure with many annealing twins. Increased up to 4% Si concentration and decreased to 2% Al concentration result in a presence of some fraction of ε martensite plates. For applied deformation conditions, the values of flow stress vary from 250 to 450MPa – increasing with decreasing deformation temperature. A relatively small values ofε max deformation at temperatures of 1050 and 950°C allow to suppose that in this range of temperature, to form a fine-grained microstructure of steels, dynamic recrystallization can be used. At a temperature of 850°C, the dynamic recrystallization leads to structure refinement after true strain of about 0.51.Research limitations/implications: To determine in detail the hot-working behaviour of developed steels, a progress of recrystallization as a function of time at deformation temperature should be investigated.Practical implications: The obtained stress-strain curves can be useful in determination of power-force parameters of hot-rolling of high-manganese austenitic steels.Originality/value: The hot-working behaviour of new-devoloped high-manganese austenitic steels containing Nb and Ti microadditions was investigated.

  6. Influence of austenite grain size on overaging treatment of continuous annealed dual phase steels

    OpenAIRE

    García-Junceda, A; García Caballero, Francisca; Iung, T; Capdevila, Carlos; García de Andrés, Carlos

    2007-01-01

    A dual phase steel with an initial coarse microstructure was refined, by means of a thermal treatment, to study the influence of the austenite grain size reached during an intercritical annealing treatment on the martensite start temperature. Thus, the effect of the austenite grain size on a subsequent overaging treatment was also investigated. It was found that a coarser austenite grain size leads to a higher martensite start temperature and a lower amount of nontempered marte...

  7. Influence of Thermal Treatment on Magnetic Properties of Steel Sheet Material Utilised in Cable Routing System

    OpenAIRE

    Elemir Usak

    2013-01-01

    The influence of relax annealing aimed at removal of the residual stresses (so-called stress-relief annealing) on various magnetic parameters, such as the relative magnetic amplitude permeability, coercivity, remanent flux density, etc. is discussed. Samples of steel cable tray material which is a part of commercially available cable routing system were investigated in order to find information about the properties important from the point of view of EMC requirements in extremely demanding in...

  8. Influence of thermal treatment on magnetic properties of steel sheet material utilised in cable routing system

    OpenAIRE

    Ušák, Elemír

    2013-01-01

    The influence of relax annealing aimed at removal of the residual stresses (so-called stress-relief annealing) on various magnetic parameters, such as the relative magnetic amplitude permeability, coercivity, remanent flux density, etc. is discussed. Samples of steel cable tray material which is a part of commercially available cable routing system were investigated in order to find information about the properties important from the point of view of EMC requirements in extremely demanding in...

  9. Microbiologically Influenced Corrosion of 2707 Hyper-Duplex Stainless Steel by Marine Pseudomonas aeruginosa Biofilm

    OpenAIRE

    Huabing Li; Enze Zhou; Dawei Zhang; Dake Xu; Jin Xia; Chunguang Yang; Hao Feng; Zhouhua Jiang; Xiaogang Li; Tingyue Gu; Ke Yang

    2016-01-01

    Microbiologically Influenced Corrosion (MIC) is a serious problem in many industries because it causes huge economic losses. Due to its excellent resistance to chemical corrosion, 2707 hyper duplex stainless steel (2707 HDSS) has been used in the marine environment. However, its resistance to MIC was not experimentally proven. In this study, the MIC behavior of 2707 HDSS caused by the marine aerobe Pseudomonas aeruginosa was investigated. Electrochemical analyses demonstrated a positive shift...

  10. Influence Of Surface Roughness On Ultra-High-Cycle Fatigue Of Aisi 4140 Steel.

    OpenAIRE

    Daniel Januário Cordeiro Gomes.; Ernani Sales Palma

    2015-01-01

    Low and high-cycle fatigue life regimes are well studied and are relatively well understood. However, recent fatigue studies on steels have shown that fatigue failures can occur at low amplitudes even below the conventional fatigue limit in the ultra-high-cycle fatigue range (life higher than 107 cycles). Fatigue life in the regime of 106 to 108 cycles-to-failure in terms of the influence of manufacturing processes on fatigue strength is examined. Specifically, the influe...

  11. Velocity hardening influence on the martensite transformation nature in constructional average alloy steel

    Institute of Scientific and Technical Information of China (English)

    Tsellermaer; V.; V.; Popova; N.; A.; Klimashin; S.; I.; Tihonikova; O.; V.; Konovalov; S.; V.; Kozlov; E.; V.; Gromov; V.; E.

    2005-01-01

    The quantitative study of the hardening velocity influence on the α-phase morphology in 30CrNi3MoVA (0.3% C, 1% Cr,3% Ni, 1% Mo, 1% V) cast average alloy steel after gomogenization (1125℃, 13 h), normalizing (980℃, 10 h) and high tempering (660℃, 10 h. with cooling on air) is the aim of this work.……

  12. Velocity hardening influence on the martensite transformation nature in constructional average alloy steel

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ The quantitative study of the hardening velocity influence on the α-phase morphology in 30CrNi3MoVA (0.3% C, 1% Cr,3% Ni, 1% Mo, 1% V) cast average alloy steel after gomogenization (1125℃, 13 h), normalizing (980℃, 10 h) and high tempering (660℃, 10 h. with cooling on air) is the aim of this work.

  13. Influence of cold rolling and annealing on mechanical properties of steel QStE 420

    OpenAIRE

    I. Schindler; M. Janošec; E. Místecký; M. Růžička; L. Čížek a; L.A. Dobrzański; S. Rusz; P. Suchánek

    2006-01-01

    Purpose: was to investigate impact of cold reduction size and annealing on mechanical properties of HSLAsteel.Design/methodology/approach: Testing of strip steel QStE 420 was based on a combination of cold rolling,recrystallization annealing, mechanical testing and metallographic analyses.Findings: It was confirmed that by a suitable combination of size of previous cold deformation and parametersof the following annealing it is possible to influence considerably a complex of mechanical proper...

  14. Virtual examinations of alloying elements influence on alloy structural steels mechanical properties

    OpenAIRE

    L.A. Dobrzański; R. Honysz

    2011-01-01

    Purpose: The paper introduces analysis results of selected alloying elements influence on mechanical properties of alloy structural steels for quenching and tempering.Design/methodology/approach: Investigations were performed in virtual environment with use of materials science virtual laboratory. Virtual investigations results were verified in real investigative laboratory.Findings: Materials researches performed with use of material science virtual laboratory in range of determining the mec...

  15. Influence of microstructure on the microbial corrosion behaviour of stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, D. A.; Ibars, J. R.; Ranninger, C. [Universidad Politecnica de Madrid (Spain)

    2000-07-01

    Several stainless steels (Type UNS S30300, S30400, S30403; S31600, S31603 and S42000) with different microstructural characteristics have been used to study the influence of heat treatments on microbiologically influenced corrosion (MIC). Bio corrosion and accelerated electrochemical testing was performed in various microbiological media. Two species of sulphate-reducing bacteria (SRB) have been used in order to ascertain the influence of microstructure. The morphology of corrosion pits produced in both chloride and chloride plus sulphide-SRB metabolites, was inspected by optical and scanning electron microscopy (SEM) complemented with energy-dispersive X-ray (EDX) analysis. Results have shown different behaviours regarding corrosion resistance in each case studied. Sensitized austenitic stainless steels were more affected by the presence of aggressive anions and pitting potential (Ep) values were more cathodic than those of as-received state. A corrosion enhancement is produced by the synergistic action of biogenic sulphides and chloride anions. Pitting corrosion in martensitic stainless steel Type UNS S42000 was found in biocorrosion test. The pitting morphology is correlated to the chemical composition, the microstructure and the electrolyte. (Author) 36 refs.

  16. Influence of microstructure on the microbial corrosion behaviour of stainless steels

    International Nuclear Information System (INIS)

    Several stainless steels (Type UNS S30300, S30400, S30403; S31600, S31603 and S42000) with different microstructural characteristics have been used to study the influence of heat treatments on microbiologically influenced corrosion (MIC). Bio corrosion and accelerated electrochemical testing was performed in various microbiological media. Two species of sulphate-reducing bacteria (SRB) have been used in order to ascertain the influence of microstructure. The morphology of corrosion pits produced in both chloride and chloride plus sulphide-SRB metabolites, was inspected by optical and scanning electron microscopy (SEM) complemented with energy-dispersive X-ray (EDX) analysis. Results have shown different behaviours regarding corrosion resistance in each case studied. Sensitized austenitic stainless steels were more affected by the presence of aggressive anions and pitting potential (Ep) values were more cathodic than those of as-received state. A corrosion enhancement is produced by the synergistic action of biogenic sulphides and chloride anions. Pitting corrosion in martensitic stainless steel Type UNS S42000 was found in biocorrosion test. The pitting morphology is correlated to the chemical composition, the microstructure and the electrolyte. (Author) 36 refs

  17. Influence of steel corrosion on Tournemire argillite after 10 years under natural underground context

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Carbon steels are possible materials for high-level radioactive waste canisters used in long term geological disposal in argillaceous environments. The French Institute of Radioprotection and Nuclear Safety (IRSN) conducts, in collaboration with EDF, an experimental program on steel/argillite interactions under natural conditions in its Underground Research Facility in Tournemire (Aveyron, France). Previous studies had investigated the corrosion rate of carbon steel (Foct et al., 2004; Foct, 2006) and modifications of the argillite (Gaudin et al., 2009) after 2 and 6 years of contact. The present study investigates re-compacted argillite/carbon steel interactions far from mechanical disturbances without water flow, after 10 years. A detailed study by X-ray microtomography (Stock, 2009) and autoradiography (Hellmuth et al., 1994) allowed us to characterize the spatial dispersion of Fe and its influence on the evolution of argillite porosity. A significant corrosion of the carbon steel sample and the development of a reddish Fe-rich front within the argillite resulting from an iron diffusion is observed. The formation of iron oxy-hydroxides (goethite, magnetite and hematite) is identified in the altered argillite. Other mineralogical changes are highlighted such as dissolution of calcite, gypsum precipitation and modification of I/S mixed-layers. The Fe distribution within the argillite at the contact appears heterogeneous. Reddish Fe-enriched haloes of maximum 4 mm within the argillite are observed macroscopically (Figure 1a) and by X-ray microtomography. Moreover, autoradiography measurements were performed and changes in porosity are observed from carbon steel to argillite (Figure 1c). The correlation with the microtomography image (Figure 1b) shows that these variations can be associated to iron diffusion areas. On the other hand, a porosity profile shows four distinct areas differing by their mean porosity: (1

  18. Influence of plastic deformation on CCT-diagrams of new-developed microalloyed steel

    Directory of Open Access Journals (Sweden)

    M. Opiela

    2012-04-01

    Full Text Available Purpose: The aim of the paper is to investigate the influence of plastic deformation and cooling conditions on a structure and a shape of CCT-diagrams of new-developed Nb-Ti-V microalloyed steel.Design/methodology/approach: The diagrams of undeformed and plastically-deformed supercooled austenite transformations for Nb-Ti-V microalloyed steel were determined. A part of the specimens were austenitized at a temperature of 885°C and next cooled to ambient temperature with a various rate from 234°C/s to 1°C/min. To investigate the influence of plastic deformation on a shape of CCT (Continuous Cooling Transformations diagrams, another part of the specimens were 50% deformed at 885°C or 1100°C and cooled to ambient temperature with a rate from 95°C/s to 1°C/min. The DIL 805A/D dilatometer, with a LVDT-type measuring head, was used to carry out dilatometric test.Findings: Performed dilatometric research revealed that the steel is characterized with Ac3=843°C, Ac1=707°C and a relatively low Ms temperature equal 370°C. Plastic deformation of steel at the temperature of 885°C prior to the start of phase transformations results in distinct acceleration of pearlitic transformation and slight translation of bainitic transformation towards shorter times.Research limitations/implications: Elaborated curves of supercooled austenite transformations of studied steel fully predispose it to production of forgings quenched directly from forging finish temperature and successively subjected to high temperature tempering.Practical implications: The obtained CCT diagrams of supercooled plastically-deformed austenite transformations can be useful in determination of cooling condition of the thermo-mechanical processing for high strength forged machine parts obtained from microalloyed steels.Originality/value: The diagrams of the plastically-deformed supercooled austenite for a new-developed microalloyed steel were obtained.

  19. Influence of alloying elements and nitrogen content on deformation resistance of chromium-nickel stainless steels

    International Nuclear Information System (INIS)

    Four groups of steels with a type Kh20N15 matrix differing in the contents of nitrogen and additional alloying element (Cu, Si, V or Nb) were studied for the influence of the alloying system on deformation resistance in hot rolling. The one-pass rolling was carried out at 900, 1000, 1100 and 1200 deg C with 20, 40 and 60 % reductions. Experimental data statistical processing showed that vanadium alloying results in a sharp increase of nitrogen content influence comparable with strain hardening. The hardening effect in copper- and silicon-containing alloys almost is independent of nitrogen concentration. Niobium-containing alloys lie between two above mentioned groups

  20. The influence of the residual copper on the pipes steel hot plasticity according to environmental requirements

    Directory of Open Access Journals (Sweden)

    Rusănescu C.O.

    2013-01-01

    Full Text Available Considering the importance of gaseous and/or liquid fuels impact on the environment, the resistance of pipelines at hot plastic deformation is important. Therefore, in order to avoid or reduce any adverse impact on the environment, the influence of residual copper on hot deformability of steel pipes was investigated in this paper. The negative copper influence was experimentally proved using torsion deformation at temperatures above 1000o, under the air and argon atmosphere. The samples were heated and then deformed at different temperatures with constant deformation rate. Also, structural analysis of investigated materials was done, using metallographic and SEM analysis.

  1. Influence of Plastic Deformation on Low Temperature Surface Hardening of Austenitic Stainless Steel by Gaseous Nitriding

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas Lundin;

    2015-01-01

    This article addresses an investigation of the influence of plastic deformation on low temperature surface hardening by gaseous nitriding of two commercial austenitic stainless steels: AISI 304 and EN 1.4369. The materials were plastically deformed to different equivalent strains by uniaxial...... tension. Gaseous nitriding of the strained material was performed in ammonia gas at atmospheric pressure at 703 K. Microstructural characterization of the as-deformed states and the nitrided case produced included X-ray diffraction analysis, reflected light microscopy, microhardness testing. The results...... demonstrate that a case of expanded austenite develops and that, in particular, strain-induced martensite has a large influence on the nitrided zone....

  2. Structural changes in fine-grained high-temperature steels under the influence of temperature stress

    International Nuclear Information System (INIS)

    Fine-grained high-temperature steels have gained great importance as materials for reactor pressure vessels. Alloying with small additions of carbide-forming elements does not only preserve the fine grain but also helps to achieve a certain retention of hardness which improves the high-temperature strength of these steels. During welding, a narrow zone of the basic material is heated over the transition temperature. The result is a coarse-grained, austenitic structure. In order to find out whether such structural changes caused by welding may damage the material during heat treatment or operation, the mechanical properties of some types of structures were tested with regard to their strength, their notched bar impact strength, and their creep rupture strength, and the findings were interpreted with the aid of scans of the surfaces of fracture and electron microscope pictures of the microstructure. The results show that the toughness of the structure of a heat influence region of the steels investigated would decrease further at operating temperatures above 2000C and below the appropriate tempering temperature if the additional heat treatment in the tempering temperature region after welding were omitted. The toughness of the heat influence region is increased by annealing to such a degree that it almost reaches that of the basic material. (GSCH)

  3. Influence of isothermal quenching of LAMC CrMnSi cast steel on impact toughness

    Institute of Scientific and Technical Information of China (English)

    JIN Bao-shi; HUANG Zhi-qiu; SHEN Da-dong

    2005-01-01

    The influence of isothermal quenching process of low-alloy and medium carbon (LAMC) CrMnSi cast steel on the impact toughness was investigated. The microstructure and mechanical property of LAMC CrMnSi cast steel were analyzed by the laser optical modulator, the scanning electron microscopy, the energy dispersive spectrometer, the hardness and impact tests. The experimental results show that the dual phases of bainite and residual austenite can be obtained by the severity isothermal quenching, the fractographies of specimens change from quasi-cleavage to dimple at 310 ℃ for 60 min, the impact toughness for specimens at the room temperature isothermally achieves 130 J/cm2, meantime and its hardness is more than 45(HRC).

  4. THIN-WALLED CROSS SECTION SHAPE INFLUENCE ON STEEL MEMBER RESISTANCE

    Directory of Open Access Journals (Sweden)

    Elżbieta Urbańska-Galewska

    2016-03-01

    Full Text Available This work describes why trending thin-walled technology is achieving popularity in steel construction sector. A purpose of this article is to present the influence of the cold-formed element cross-section shape on an axial compression and a bending moment resistance. The authors have considered four different shapes assuming constant section area and thickness. Calculations were based on three different steel grades taking into account local, distortional and overall buckling. The results are presented in a tabular and a graphical way and clearly confirm that cross-section forming distinctly impact the cold-formed member resistance. The authors choose these cross-sections that work better in compression state and the other (those slender and high that function more efficiently are subjected to bending.

  5. Influence of Hot Rolling Conditions on the Mechanical Properties of Hot Rolled TRIP Steel

    Institute of Scientific and Technical Information of China (English)

    LI Zhuang; WU Di

    2008-01-01

    Influence of hot rolling conditions on the mechanical properties of hot rolled TRIP steel was investigated.Thermomechanical control processing(TMCP)was conducted by using a laboratory hot rolling mill,in which three different kinds of finish rolling temperatures were applied.The results show that polygonal ferrite,granular bainite and larger amount of stabilized retained anstenite can be obtained by controlled rolling processes.The finer ferrite grain size is produced through the deformation induced transformation during deformation rather than after deformation,which affects the mechanical properties of hot rolled TRIP steel.Mechanical properties increase with decreasing finish rolling temperature due to the stabilization of retained austenite.Ultimate tensile strength(UTS),total elongation(TEL)and the product of ultimate tensile strength and total elongation(UTS×TEL)reaches optimal values(791 MPa,36% and 28 476 MPa%,respectively)whenthe specimen was hot rolled for 50% reduction at finish rolling temperature of 700℃.

  6. Influence of Mn Content and Hot Deformation on Transformation Behavior of C-Mn Steels

    Institute of Scientific and Technical Information of China (English)

    LI Long; DING Hua; DU Lin-xiu; WEN Jing-lin; SONG Hong-mei; ZHANG Pi-jun

    2008-01-01

    The hot deformation behaviors and the microstructural evolution of plain C-Mn steels with similar contents of C and Si but different contents of Mn have been investigated by compressive processing using Gleeble-1500 mechanical simulator. Influence of Mn and hot deformation on continuous cooling transformation of steels has been studied. The experimental results showed that deformation in austenite region accelerated transformation process, and the extent is dependent on the hot deformation and cooling conditions. The hot deformation would promote transformation process, but the increase of transformation temperature is dependent on Mn contents. The results have also shown that the effect of deformation on ferrite transformation becomes more obvious with the increase of Mn content at relatively low cooling rate.

  7. Influence of the cooling rate on the corrosion resistance of duplex cast steel

    Directory of Open Access Journals (Sweden)

    B. Kalandyk

    2013-01-01

    Full Text Available The results of the influence of the cooling rate of the casting made of the acid-resistant ferritic - austenitic cast steel on the microstructure and corrosion resistance are presented in the paper. Samples cut out from the walls of the casting being cooled at the cooling rate of 3,2 - 0,5 ºC/s were used in the study. Different cooling rates create favorable conditions for the segregation processes lowering properties of castings. It was found, that differences in the polarization curves occur only in the more aggressive corrosive environment. The reason of such behaviour of cast steel is the segregation of elements dissolved in austenite and the difference in the volume fraction of ferrite and austenite in the walls of the different thickness.

  8. Microbially influenced corrosion of stainless steels; Stainless ko no biseibutsu fushoku ni kansuru chosa kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Y.; Misawa, M. [Kansai Electric Power Co. Inc., Osaka (Japan)

    1998-11-30

    It is generally known, though not fully clarified, that stainless steel pipes, particularly those exposed to natural sea water; are susceptible to microbially influenced corrosion (MIC) at welded joints. In an effort to gain a better understanding of the mechanism, factors affecting the MIC behavior in welded stainless steel pipe joints were experimentally investigated. Results of the study indicate there are two major contributing factors to MIC development in the weld region. One is the circumferentially protruding shape effect of the deposited metal, provinding an environment that allows aquatic microorganisms to adhere to the downstream side of the welded bead surface. The other factor is the declining corrosion resistance in the welded joint due to the oxide film formation caused by insufficient shielding during welding. There factors, if combined, produce higher susceptibility to MIC in the weld than in the base metal. (author)

  9. Influence of two different heat treatment procedures on mechanical and fracture properties of 65 Si 7 steel

    International Nuclear Information System (INIS)

    This paper deals with the results of investigations of two different heat treatment procedures and their influence on some mechanical properties as well as on the magnitude of some fracture mechanics parameters for a particular type of steel. The experimental investigations were performed on the specimens made of 65Si7 steel. The processes occurring by tempering of two different microstructures of the steel, i. e. martensite and lower bainite were investigated. An advantage of austempering over hardening and tempering is in obtaining the bainite microstructure. Steel of bainite microstructure has a greater toughness, ductility, contraction, fatigue strength and a better fracture toughness than a tempered martensite of the same type of steel. A bainite microstructure also gives a better resistance to thermal fatigue in comparison with martensite microstructure. The above mentioned improved values of mechanical properties refer to the untempered state of bainite. (author)

  10. Microbially influenced corrosion of 303 stainless steel by marine bacterium Vibrio natriegens: (II) Corrosion mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Yin Yansheng, E-mail: yys2006@ouc.edu.cn [Institute of Ocean Materials and Engineering, Shanghai Maritime University, Shanghai 200135 (China); Cheng Sha [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Chen Shougang, E-mail: sgchen@ouc.edu.cn [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Tian Jintao; Liu Tao; Chang Xueting [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China)

    2009-04-30

    Electrochemical techniques (electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves) and surface analysis (scanning electron microscopy (SEM)) were carried out to determine the possible mechanism of the microbially influenced corrosion of 303 stainless steel (303 SS) by marine bacterium Vibrio natriegens (V. natriegens). In order to clarify the mechanism, 303 SS coupons were immersed in four different mediums. EIS results were interpreted with different equivalent circuits to model the physicoelectric characteristics of the electrode/biofilm/solution interface. The results showed that N{sub 2}-fixation actually promoted the corrosion of 303 SS; however, the influence of the produced NH{sub 3} was negligible. It can be speculated that the electron transfer and/or the nitrogenase catalyzing the process may influence the corrosion.

  11. Influence of formulated neem seed oil and jatropha curcas seed oil on wire drawing of mild steel and medium carbon steel at elevated temperatures

    Directory of Open Access Journals (Sweden)

    Mamuda Muhammad

    2016-09-01

    Full Text Available So many facets of hot wire drawing process, despite its extensive and long time employment in the industries, still remain unclear, due to want of systematic investigation of the process. This work investigated the influence of formulated neem seed and jatropha seed oil as lubricants, using antimony dialkyl dithiocarbamates (ADTC as an additive, on wire drawing process. The suitability of the bio-based oils in friction and wear control during wire drawing process were investigated, using a four ball tester. Experimental drawing process, using a Tungsten Carbide die and the formulated lubricants was carried out on mild steel and medium carbon steel rod (6 and 8mm diameter respectively at temperatures from 20OC to 750OC, on a drawing bench. The stresses and the temperature distribution profiles along the work-piece were reported. Up to 45% of reductions in area, without wire fracture, achieved on the drawing of the medium carbon steel have equally been reported.

  12. Influence of Alloying Elements Corrosion Resistance of Cold on Mechanical Properties and Rolled C-Mn-Si TRIP Steels

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ling-yun; WU Di; LI Zhuang

    2012-01-01

    The rust layer plays an important role in the corrosion of steel in chlorinated environments. Salt spray, po- tentiodynamic polarization curve and tensile test were conducted in laboratory for the specimens after two-stage heat treatment. The influence of the alloying elements on mechanical properties and corrosion resistance of three kinds of steels was investigated by observing the microstructure and the morphologies of rust layer. The results show that the highest value (29%) of total elongation for steel A is obtained. The mechanical property of the specimen for steel C exhibits best strength ductility balance (21 384 MPa ·%) because of the presence of the multiphase microstructures after a two-stage heat treatment and the addition of the alloying elements. The corrosion products are known to be a complex mixture of Fe3O4 , Fe2O3 and α-FeOOH for steel C. The presence of the alloying elements results in the for mation of compact and dense rust layers in steel B and C. Passive film protects the substrate of TRIP (transformation induced plasticity) steel containing a complex mix of multiphase. Superior corrosion performance is exhibited for steel C with low alloying contents due to the enrichment of alloying elements within the rust layers.

  13. Influence of thermo-mechanical treatment on the tensile properties of a modified 14Cr–15Ni stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Vijayanand, V.D., E-mail: vdvijayanand@igcar.gov.in; Laha, K.; Parameswaran, P.; Nandagopal, M.; Panneer Selvi, S.; Mathew, M.D.

    2014-10-15

    The titanium modified 14Cr–15Ni austenitic stainless steel is used as clad and wrapper material for fast breeder nuclear reactor. Thermo-mechanical treatments consisting of solution annealing at two different temperatures of 1273 and 1373 K followed by cold-work and thermal ageing have been imparted to the steel to tailor its microstructure for enhancing strength. Tensile tests have been carried out on the thermo-mechanically treated steel at nominal strain rate of 1.6 × 10{sup −4} s{sup −1} over a temperature range of 298–1073 K. The yield stress and the ultimate tensile strength of the steel increased with increase in solution treatment temperature and this has been attributed to the fine and higher density of Ti(C,N) precipitate. Tensile flow behaviour of the steel has been analysed using Ludwigson and Voce constitutive equations. The steel heat treated at higher solution temperature exhibited earlier onset of cross slip during tensile deformation. The rate of recovery at higher test temperatures was also influenced by variations in solution heat treatment temperature. In addition, dynamic recrystallization during tensile deformation at higher temperatures was profound for steel solution heat-treated at lower temperature. The differences in flow behaviour and softening mechanisms during tensile testing of the steel after different heat treated conditions have been attributed to the nature of Ti(C,N) precipitation.

  14. Influence of delta ferrite and dendritic carbides on the impact and tensile properties of a martensitic chromium steel

    International Nuclear Information System (INIS)

    Martensitic chrome steels with a high content of chromium incline to form delta ferrite frequently accompanied by massive dendritic carbide precipitations. Both phases mostly influence the mechanical properties of this steel in countercurrent manner. The relatively soft delta ferrite causes an increase of ductility and toughness, whilst the brittle dendritic carbides decreases both. Both phases mostly decrease the strength of the steel. One or the other influence will be dominant in dependence of the quantitative relation of the two phases. This is the cause for very different statements in the literature. The dendritic carbides should be avoided using a cooling rate of more than 103 K/min after the austenitization, because this phase mostly impairs the mechanical properties of the steel. However, the delta ferrite without dendritic carbides can be tolerated mostly. (orig.)

  15. Properties of a Nb-V-Ti microalloyed steel influenced by cold rolling and annealing

    Directory of Open Access Journals (Sweden)

    M. Janošec

    2007-01-01

    Full Text Available Purpose: was to investigate impact of cold forming and annealing on microstructural and mechanical propertiesof HSLA steel.Design/methodology/approach: Testing of Nb-V-Ti microalloyed strip steel was based on a combination ofcold rolling, recrystallization annealing, mechanical testing, metallography and TEM.Findings: It was confirmed that by a suitable combination of size of previous cold reduction size and parametersof the following annealing it is possible to influence considerably a complex of mechanical propertiesof particular strips. Strength as well as plastic properties depended on the course of recrystallization andprecipitates’ coarsening during annealing.Research limitations/implications: The experiment should be supplemented by the more detailed analyses ofmicrostructure.Practical implications: The results may be utilized for optimization of terms of heat treatment in a cold rollingmill, especially in accordance with specific requirements for a relation between plastic and strength propertiesof the investigated steel.Originality/value: Research possibilities of VSB-TUO in the sphere of cold rolling of Nb-V-Ti HSLA steelwere introduced in combination with the complex approach to processing of the obtained results.

  16. Influence of silicon addition on the mechanical properties and corrosion resistance of low-alloy steel

    Indian Academy of Sciences (India)

    M Hebda; H Dębecka; J Kazior

    2015-12-01

    The addition of silicon to low-alloy steel allows to modify the materials' microstructure and thus to improve their corrosion resistance and mechanical properties. The influence of adding different amounts of silicon on the properties (density, transverse rupture strength, microhardness and corrosion resistance) and microstructure of low-alloy steel was investigated. Samples were prepared via the mechanical alloying process, which is the most useful method to homogeneously introduce silicon to low-alloy steel. Sintering was performed by using the spark plasma sintering (SPS) technique. After the SPS process, half of each of the obtained samples was heat-treated in a vacuum furnace. The results show that high-density materials were achieved, and a homogeneous and fine microstructure was obtained. The investigated compositions containing 1 wt% of silicon had better corrosion resistance than samples with 3 wt% of silicon addition. Furthermore, corrosion resistance as well as the mechanical and plastic properties of the samples with 1 wt% of silicon can be further improved by applying heat treatment.

  17. Study of pitting corrosion in line-pipe steel under the influence of remanent magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Espina-Hernandez, J.H.; Caleyo, F.; Hallen, J.M. [Instituto Politecnico Nacional (IPN), Zacatenco (Mexico)

    2009-07-01

    The influence of remanent magnetization on pitting corrosion in line-pipe steels is studied. Pitting corrosion experiments have been carried out on samples of an API 5L grade 52 steel under a magnetization level of the same order of magnitude of the remanent magnetization in the pipeline wall after in-line inspection based on magnetic flux leakage. The samples were magnetized using rings of the same grade as the investigated steel. Immediately after magnetization, the investigated samples were subjected to pitting by immersing them in a solution containing dissolved Cl{sup -} and SO{sup 2-}{sub 4} and ions. The pitting experiments were conducted during a seven days period. The pit depth distribution and the maximum pit depth in each sample were recorded and used to conduct extreme value analyses of the pitting process in magnetized and non-magnetized control samples. The statistical assessment of the pitting corrosion data collected during this study shows that the magnetic field reduces the average depth of the pit population and also the extreme pit depth values that can be predicted from the maximum values observed in the magnetized samples in comparison with to the non-magnetized control samples. Scanning electron microscopy observations show that the magnetic field alters the pit morphology by increasing the pit mouth opening. (author)

  18. INFLUENCE OF QUANTITATIVE ALLOYING OF TOOL STEELS FOR HOT DEFORMATION ON THE LEVEL OF HARDENING

    Directory of Open Access Journals (Sweden)

    V. N. Fedulov

    2015-01-01

    Full Text Available The influence of complexly experimental tool steels: C (0,4–0,50%, Si (0,6–1,2%, Mn (0,17–0,8%, Cr (0,8–3%, W (0,9– 4%, Mo (0,01–3.5% and V (0,28–1,8% on their ability to hardening due to only high-temperature tempering after induction melting, casting in the ceramic mold and air cooling (without deformation and after the various modes of complete heat treatment cycle

  19. Influence of Hot Deformation and Subsequent Austempering on the Mechanical Properties of Hot Rolled Multiphase Steel

    Institute of Scientific and Technical Information of China (English)

    Zhuang LI; Di WU

    2006-01-01

    Influence of hot deformation and subsequent austempering on the mechanical properties of hot rolled multiphase steel was investigated. Thermo-mechanical control processing (TMCP) was conducted by using a laboratory hot rolling mill, where three different kinds of finishing rolling reduction, and austemperings with various isothermal holding duration were applied. The results have shown that a multiphase microstructure consisting of polygonal ferrite, granular bainite and larger amount of stabilized retained austenite can be obtained by controlled rolling processes. Mechanical properties increase with increasing the amount of deformation because of the stabilization of retained austenite. Ultimate tensile strength (σb), total elongation (δ)36% and 28476 MPa%, respectively) at optimal processes.

  20. The Influence of the Loading Rate on the Mechanical Properties of Drawing Steel Sheet

    Directory of Open Access Journals (Sweden)

    Buršák, M.

    2006-01-01

    Full Text Available The paper analyzes the influence of the loading rate in the interval from 1 to 1000 mm/min on the mechanical properties of drawing steel sheet H260LAD with the gauge of 1 mm, used for the manufacture of automotive parts, under tension and bending conditions. It describes the aspects of material characteristics under tension and bending conditions, while bending tests were made on notched specimens (a modified impact bending test. The paper presents knowledge that using a modified notch toughness test it is possible to achieve the pressability (formability characteristics corresponding to dynamic strain rates even under the static loading.

  1. The influence of gouge defects on failure pressure of steel pipes

    International Nuclear Information System (INIS)

    Failure pressure of API X42 steel pipes with gouge defects was estimated through a nonlinear finite element (FE) analysis. The effect of gouge length on failure pressure of different pipe diameters was investigated. Stress modified critical strain (SMCS) model was applied as in predicting the failure of the pipe. The model uses strain based criteria to predict the failure. For validation of the model, the FE results were compared to experimental data in literature showing overall good agreement. The results show that the gouge length has significant influence on failure pressure. A smaller pipe diameter gives highest value of failure pressure

  2. Influence of hot-working conditions on a structure of high-manganese austenitic steels

    OpenAIRE

    A. Grajcar; L.A. Dobrzański; W. Borek

    2008-01-01

    Purpose: The aim of the paper is to determine the influence of hot deformation conditions on σ-ε curves and structure changes of new-developed high-manganese austenitic steels.Design/methodology/approach: The force-energetic parameters of hot-working were determined in hot-compression tests performed in a temperature range of 850 to 1050°C by the use of the Gleeble 3800 thermomechanical simulator. Evaluation of processes controlling work hardening at 850°C were identified by microstructure ob...

  3. Influence on corrosion resistance of superficial strain hardening of parts made of austenitic stainless steels

    International Nuclear Information System (INIS)

    Reactivity of strain hardened stainless steel 18-10 and 18-10 Mo in oxidizing media is very different at the surface and in the metal core. Surface corrosion or protection is very sensitive to superficial strain hardening resulting of mechanical treatments. Three physical phenomena are directly strain hardening dependent and have important consequences on corrosion resistance: 1) increase of diffusion rate of the different alloy elements, especially chromium; 2) residual superficial strain influence on stress corrosion and 3) structural transformation of metastable austenite

  4. Influence of Holding Time After Deformation on Bainite Transformation in Niobium Microalloyed Steel

    Institute of Scientific and Technical Information of China (English)

    YI Hai-long; DU Lin-xiu; WANG Guo-dong; LIU Xiang-hua

    2007-01-01

    Using Gleeble-1500 system, the influence of holding time on bainite transformation in deformed niobium microalloyed steel during continuous cooling was analyzed, and the carbides in upper bainite were also systematically researched. The results show that the occurrence of the static recrystallization decreases the amount of bainite with an increase in the holding time and the emergence of retained austenite (RA) with the longer holding time. Two types of carbides were observed in upper bainite with regard to their precipitation sites. They either existed between the bainite ferrite laths or co-existed with RA. The formation mechanism of two kinds of carbides was analyzed by combining TEM micrographs with the model.

  5. Comparison of the Influences of Phosphorus and Sulfur on the Reheat Cracking Sensitivity of Cr-Mo Steels

    OpenAIRE

    Tamaki, Koreaki; Suzuki, Jippei; 玉置, 維昭; 鈴木, 実平

    1988-01-01

    The influences of phosphorus and sulfur on the reheat cracking sensitivity of 1%Cr-0.5%Mo steels were investigated using experimental steel specimens doped with phosphorus or sulfur. The cracking sensitivity was evaluated by terms of critical restraint stress obtained by an implant test. And the metallugical experiments were made on the phosphorus segregation to the austenite grain boundary, and on the diffusible sulfur concentration. Phosphorus segregation was measured by the grain boundary ...

  6. CHANGE OF MORPHOLOGY OF THE CARBON CHROME-MOLYBDENUM STEEL STRUCTURE UNDER THE INFLUENCE OF THERMAL TREATMENT

    Directory of Open Access Journals (Sweden)

    V. A. Lutsenko

    2010-01-01

    Full Text Available Influence of temperature-temporal parameters of thermal treatment on changing of structure and characteristics of carbon chrome-molybdenum steel is studied. It is shown that there are considerable areas with granular morphology of cementite in metal structure after high-temperature tempering, what provides lowering of microhardness of steel by 25%, and after medium-temperature tempering there are no essential structural changes.

  7. CHANGE OF MORPHOLOGY OF THE CARBON CHROME-MOLYBDENUM STEEL STRUCTURE UNDER THE INFLUENCE OF THERMAL TREATMENT

    OpenAIRE

    V. A. Lutsenko; N. I. Anelkin; T. N. Golubenko; Shcherbakov, V. I.; O. V. Lutsenko; L. A. Drobyshevskij

    2016-01-01

    Influence of temperature-temporal parameters of thermal treatment on changing of structure and characteristics of carbon chrome-molybdenum steel is studied. It is shown that there are considerable areas with granular morphology of cementite in metal structure after high-temperature tempering, what provides lowering of microhardness of steel by 25%, and after medium-temperature tempering there are no essential structural changes.

  8. Computer modelling system of the chemical composition and treatment parameters influence on mechanical properties of structural steels

    OpenAIRE

    L.A. Dobrzański; R. Honysz

    2009-01-01

    Purpose: This paper presents Neuro-Lab. It is an authorship programme, which use algorithms of artificial intelligence for structural steels mechanical properties estimation.Design/methodology/approach: On the basis of chemical composition, parameters of heat and mechanical treatment and elements of geometrical shape and size this programme has the ability to calculate the mechanical properties of examined steel and introduce them as raw numeric data or in graphic as influence charts. Possibl...

  9. Influence of phosphorus content and quenching/tempering temperatures on fracture toughness and fatigue life of SAE 5160 steel

    OpenAIRE

    Danilo Borges Villarino de Castro; Jaime Milan Ventura; Cassius Olivio Figueiredo Terra Ruckert; Dirceu Spinelli; Waldek Wladimir Bose Filho

    2010-01-01

    This study investigates the influence of quenching/tempering temperatures on the fracture toughness and fatigue life of SAE 5160 steel, considering different phosphorus contents. Quenching and tempering treatments were applied to samples removed from different bars of commercial SAE 5160 steel with different P content. Three different austenitizing temperatures for quenching: 850, 900 and 1000 ºC and a constant holding time of 15 minutes were used. The oil temperature for quenching was kept a...

  10. Influence of rare earth metals on the nucleation and solidification behavior of iron and 1045 steel

    Science.gov (United States)

    Li, H.; McLean, A.; Rutter, J. W.; Sommerville, I. D.

    1988-06-01

    Two series of experiments have been conducted to determine the influence of rare earth additions on the nucleation and crystallization behavior of pure iron and 1045 steel. In the first series, additions of rare earth suicide or cerium dioxide powder to two-Kg 1045 steel ingots indicated that rare earth suicide can refine the as-cast structure of such ingots. However, if the holding time after rare earth silicide addition is over two minutes, the grain refinement decreases. With cerium dioxide additions, a relatively large columnar zone was obtained. In the second series, the effects of cerium metal or cerium dioxide powder additions on the degree of undercooling obtainable in pure iron and 1045 steel were examined by the lévitation melting method. Surface tension measurements of the levitated droplets were carried out at the same time to investigate the possible effects of surface tension variations on the nucleation and crystallization behavior of the metals. The experimental data show that rare earth inclusions can greatly reduce the degree of undercooling of iron and steel, and that a small amount of dissolved cerium can further reduce the degree of undercooling of levitated droplets. The structure and reaction products obtained with Fe-Ce levitated droplets were examined with both optical and scanning electron microscopy as well as X-ray diffraction analysis. The experimental results clearly indicated that cerium solute redistribution during solidification is the dominant factor in refining the as-cast structure. A nucleation and solidification model for the Fe-Ce levitated droplets has been developed, which can successfully explain the experimental results.

  11. The Influence of Corrosion and Cross-Section Diameter on the Mechanical Properties of B500c Steel

    Science.gov (United States)

    Apostolopoulos, Ch. Alk.

    2009-03-01

    Corrosion is a negative contributor on the structural integrity of concrete structures and leads to degradation of the mechanical properties of steel rebar. Exposure to chloride, seawater, salt and saltwater and deicing chemical environments influences the concrete-steel bond and weakens it. A considerable strength factor of the two-phase steel B500c (martensitic, ferritic-perlitic) is considered to be the outer martensitic cortex thickness, which varies according to the area of the rebar cross section. In order to evaluate the influence of corrosion and the size of the area on the mechanical properties of B500c steel, an experimental investigation was conducted on B500c ribbed steel rebar of 8, 12, 16, and 18 mm diameter, and which were artificially corroded for 10, 20, 30, 45, 60, 90, and 120 days. The laboratory tests suggest that corrosion duration and rebar cross-sectional area size had a significant impact on the strength and ductility degradation of the specimens. The tensile mechanical properties before and after corrosion indicated progressive variation and drastic drop in their values. The extended salt spray exposure enhanced the damage and created pits and notches, resulting in stress concentration points and progressive reduction of ductility and available energy. Anti-seismic design and codes that ignore the influence of the size of the cross-section area and the level of corrosion and mechanical behavior of reinforcing steel could lead to unpredictable performance during severe ground motion.

  12. Factors Influencing the Wear Behavior of Sintered Steels%影响烧结钢磨损行为的因素

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A review was made on the research progress of wear behavior of sintered steels in recent years. Wear is not an intrinsic property of sintered steels, which is strongly influenced by the wear test conditions. However, many other factors that determine the mechanical properties of sintered steels also affect the wear behavior. Porosity has different effects on the wear of sintered steels depending on the application conditions. Under dry sliding condition, higher porosity results in lower wear resistance. The influence of microstructures on wear resistance is in the order: carbide, martensite, bainite and lamellar pearlite. The wear resistance increases with hardness, but this relationship changes with the porosity and microstructures of sintered steels.

  13. Influence of annealing treatment on microstructure and properties of cold sprayed stainless steel coatings

    Institute of Scientific and Technical Information of China (English)

    Xianming MENG; Junbao ZHANG; Jie ZHAO; Wei HAN; Yongli LIANG

    2011-01-01

    304 stainless steel coatings had been deposited on carbon-steel substrate by cold spray technique, vacuum annealing treatment was applied to the coatings with different temperatures, and the influence of annealing treatment on the microstructure and electrochemical behavior of the coatings in 3.5% NaCl were analyzed. The results indicated that, the cold sprayed coating was constituted by the flattened particles, and the interfaces were clearly observed between the deposited particles. It was also found that annealing treatment led to the recovery and recrystallization of the elongated grains in the as-sprayed coatings with the increase of annealing temperature.When the annealing temperature achieved to 950 ℃, the interface of particles was disappeared and the coating's structure was made of new recrystallization anstenite grains. Annealing treatment increased the potential volts, and reduced the corrosion rate with the increase of annealing temperature. The electrical corrosion morphology indicated that, the corrosion was firstly at the distortion area and the crevice corrosion mechanism played an important part. Based on these results, processes active during annealing treatment are kinetically dependent and strongly influenced by the annealing treatment temperature.

  14. Fatigue behaviour of 304L steel welded structures: influence of residual stresses and surface mechanical finishing

    International Nuclear Information System (INIS)

    This study focuses on the influence of residual stresses and surface mechanical finishing on lifetime of stainless steel 304L welded structures. Residual stresses are determined on specific specimens of three types: base-metal, as-welded and ground-welded specimens. Each type is submitted to fatigue tests in order to assess the influence of these parameters on the lifetime, and to determine their evolution. The experiments show that an important surface stress concentration is located in the weld root of as-welded structures, which has a negative effect on the fatigue life. The grinding operation generates high-level surface residual stresses but the lifetime is higher thanks to the reduction of the notch effect. The fatigue test results are compared to the nuclear industry best-fit S-N curves. This enables the determination of correction factors related to fatigue test results of polished specimens, and to assess the lifetime of structures. (author)

  15. Influence of plastic deformation on low temperature surface hardening of stainless steel by gaseous nitriding

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas Lundin;

    2015-01-01

    This article addresses an investigation of the influence of plastic deformation on low temperature surface hardening by gaseous nitriding of three commercial austenitic stainless steels: AISI 304, EN 1.4369 and Sandvik Nanoflex® with various degrees of austenite stability. The materials were...... plastically deformed to different equivalent strains by uniaxial tension. Gaseous nitriding of the strained material was performed in ammonia at atmospheric pressure in the temperature range 693-703 K. Microstructural characterization of the as-deformed states and the nitrided case included X-ray diffraction...... analysis, reflected light microscopy and microhardness indentation. The results demonstrate that a case of expanded austenite develops and that, in particular, the presence of strain-induced martensite in the initial (deformed) microstructure has a large influence on the nitrided zone....

  16. Influence of Freeze-Thaw Damage on the Steel Corrosion and Bond-Slip Behavior in the Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Fangzhi Zhu

    2016-01-01

    Full Text Available This paper mainly studies the behavior of steel corrosion in various reinforced concrete under freeze-thaw environment. The influence of thickness of concrete cover is also discussed. Additionally, the bond-slip behavior of the reinforced concrete after suffering the freeze-thaw damage and steel corrosion has also be presented. The results show that the freeze-thaw damage aggravates the steel corrosion in concrete, and the results become more obvious in the concrete after suffering serious freeze-thaw damage. Compared with the ordinary concrete, both air entrained concrete and waterproofing concrete possess better resistance to steel corrosion under the same freeze-thaw environment. Moreover, increasing the thicknesses of concrete cover is also an effective method of improving the resistance to steel corrosion. The bond-slip behavior of reinforced concrete with corroded steel decreases with the increase of freeze-thaw damage, especially for the concrete that suffered high freeze-thaw cycles. Moreover, there exists a good correlation between the parameters of bond-slip and freeze-thaw cycles. The steel corrosion and bond-slip behavior of reinforced concrete should be considered serious under freeze-thaw cycles environment, which significantly impact the durability and safety of concrete structure.

  17. THE INFLUENCE OF POSTHEAT TREATMENT ON FERRITE REDISTRIBUTION IN DUPLEX STEELS ELECTRON BEAM WELDS

    OpenAIRE

    Zita Iždinská; František Kolenič

    2009-01-01

    The duplex stainless steel is two-phase steel with the structure composed of austenite and ferrite with optimum austenite/ferrite proportion 50%. At present, classical arc processes for welding duplex steels are generally regarded as acceptable. On the other hand electron and laser beam welding is up to now considered less suitable for welding duplex steels. The submitted work presents the results of testing various thermal conditions at welding duplex stainless steel with electron beam. It w...

  18. Influence of Corrosion on the Abrasion of Cutter Steels Used in TBM Tunnelling

    Science.gov (United States)

    Espallargas, N.; Jakobsen, P. D.; Langmaack, L.; Macias, F. J.

    2015-01-01

    Abrasion on tunnel boring machine (TBM) cutters may be critical in terms of project duration and costs. Several researchers are currently studying the degradation of TBM cutter tools used for excavating hard rock, soft ground and loose soil. So far, the primary focus of this research has been directed towards abrasive wear. Abrasive wear is a very common process in TBM excavation, but with a view to the environment in which the tools are working, corrosion may also exert an influence. This paper presents a selection of techniques that can be used to evaluate the influence of corrosion on abrasion on TBM excavation tools. It also presents the influence of corrosion on abrasive wear for some initial tests, with constant steel and geomaterial and varying properties of the excavation fluids (soil conditioners, anti-abrasion additives and water). The results indicate that the chloride content in the water media greatly influences the amount of wear, providing evidence of the influence of corrosion on the abrasion of the cutting tools. The presence of conditioning additives tailored to specific rock or soil conditions reduces wear. However, when chloride is present in the water, the additives minimise wear rates but fail to suppress corrosion of the cutting tools.

  19. Influence of Rare Earths on Improve Impact Property of Structural Alloy Steel with Extra Low Sulfur and Oxygen

    Institute of Scientific and Technical Information of China (English)

    Guo Feng; Lin Qin

    2007-01-01

    The influence of rare earth lanthanum and cerium on impact property of structural alloy steel with extra low sulfur and oxygen was studied by impact test and microanalysis. The results showed that rare earths increased impact power of the steel when their contents were about 0.005%. Proper addition of rare earths could purify grain boundaries and decrease amount of inclusions, and reduced the possibility of crack growth along grain boundaries and through inclusions. Therefore, such steel could absorb more crack growth energy while it was impacted. However, if the content of rare earths is excessive, the grain boundary would be weakened and brittle-hard phosphates and Fe-RE intermetallic would be formed, which worsened impact toughness of steel.

  20. Influence of reheating and cooling conditions on structure and mechanical properties of C-Mn-Si steel

    Directory of Open Access Journals (Sweden)

    T. Kvačkaj

    2008-07-01

    Full Text Available The paper deals with structure and properties development of AHSS (advance high-strength steel and UHSS (ultra high-strength steel steel grades for various groups of automotive parts. C-Mn-Si type steel properties are evaluated based on the results of laboratory controlled rolling and cooling. The important influence on mechanical and plastic properties, amount of residual austenite (RA and final structural type has, except for cooling rate, also starting temperature of intensive cooling (TIC which follows after hot plastic deformations. If TIC is from interval of 620-760°C the final structure predominantly consists of ferrite with RA. Mostly acicular ferrite with RA, as well as bainite with RA was obtained when TIC was kept in the range of 760-850°C.

  1. Study of corrosion behavior of a 22% Cr duplex stainless steel : influence of nano-sized chromium nitrides and exposure temperature

    OpenAIRE

    Bettini, Eleonora; Kivisäkk, Ulf; Leygraf, Christofer; Pan, Jinshan

    2013-01-01

    Chromium nitrides may precipitate in duplex stainless steels during processing and their influence on the corrosion behavior is of great importance for the steel performance. In this study, the influence of nano-sized quenched-in chromium nitrides on the corrosion behavior of a heat treated 2205 duplex stainless steel was investigated at room temperature and 50 °C (just above critical pitting temperature). The microstructure was characterized by SEM/EDS and AFM analyses, and quenched-in nitri...

  2. The Influence of Post Weld Heat Treatment in Alloy 82/182 Dissimilar Metal Weld between Low Alloy Steel and 316L Stainless Steel

    International Nuclear Information System (INIS)

    Dissimilar metal welds (DMWs) using an Alloy 82/182 are widely used to join low alloy steel components and stainless steel pipes in pressurized water reactors (PWRs). It has been reported that tensile residual stress would be generated within DMWs during the welding processes. It is thought as main reason for primary water stress corrosion cracking (PWSCC) resulting in deterioration of long-term integrity. The application of post weld heat treatment (PWHT) has been considered to reduce the tensile residual stress after welding process. Meanwhile, the PWHT could affect the changes in microstructure, mechanical properties, and corrosion resistance. Therefore, in this study, the effects of PWHT on the microstructure, mechanical properties and corrosion behaviors of base metals of low alloy steel and stainless steel and welding materials of Alloy 82/182 are evaluated. The influence of PWHT in DMW has been investigated. SA 508 and 316L SS exhibited tempered bainite and austenitic grains with a few residual stringer type ferrite. Grain boundary carbides are not precipitated owing to low carbon and insufficient exposure time in 316L SS. The change of mechanicals properties in base metals is not observed. In case of Alloy 182, after PWHT, grain boundaries are covered with film-like continuous Cr-rich carbides

  3. The Influence of Post Weld Heat Treatment in Alloy 82/182 Dissimilar Metal Weld between Low Alloy Steel and 316L Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sunghoon; Hong, Jong-Dae; Jang, Changheui [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Lee, Kyoung Soo [KHNP-CRI, Daejeon (Korea, Republic of)

    2014-10-15

    Dissimilar metal welds (DMWs) using an Alloy 82/182 are widely used to join low alloy steel components and stainless steel pipes in pressurized water reactors (PWRs). It has been reported that tensile residual stress would be generated within DMWs during the welding processes. It is thought as main reason for primary water stress corrosion cracking (PWSCC) resulting in deterioration of long-term integrity. The application of post weld heat treatment (PWHT) has been considered to reduce the tensile residual stress after welding process. Meanwhile, the PWHT could affect the changes in microstructure, mechanical properties, and corrosion resistance. Therefore, in this study, the effects of PWHT on the microstructure, mechanical properties and corrosion behaviors of base metals of low alloy steel and stainless steel and welding materials of Alloy 82/182 are evaluated. The influence of PWHT in DMW has been investigated. SA 508 and 316L SS exhibited tempered bainite and austenitic grains with a few residual stringer type ferrite. Grain boundary carbides are not precipitated owing to low carbon and insufficient exposure time in 316L SS. The change of mechanicals properties in base metals is not observed. In case of Alloy 182, after PWHT, grain boundaries are covered with film-like continuous Cr-rich carbides.

  4. Influence of localized deformation on A-286 austenitic stainless steel stress corrosion cracking in PWR primary water

    International Nuclear Information System (INIS)

    Irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels is known to be a critical issue for structural components of nuclear reactor cores. The deformation of irradiated austenitic stainless steels is extremely heterogeneous and localized in deformation bands that may play a significant role in IASCC. In this study, an original approach is proposed to determine the influence of localized deformation on austenitic stainless steels SCC in simulated PWR primary water. The approach consists in (i) performing low cycle fatigue tests on austenitic stainless steel A-286 strengthened by γ' precipitates Ni3(Ti,Al) in order to shear and dissolve the precipitates in intense slip bands, leading to a localization of the deformation within and in (ii) assessing the influence of these γ'-free localized deformation bands on A-286 SCC by means of comparative CERT tests performed on specimens with similar yield strength, containing or not γ'-free localized deformation bands. Results show that strain localization significantly promotes A-286 SCC in simulated PWR primary water at 320 and 360 C. Moreover, A-286 is a precipitation-hardening austenitic stainless steel used for applications in light water reactors. The second objective of this work is to gain insights into the influence of heat treatment and metallurgical structure on A-286 SCC susceptibility in PWR primary water. The results obtained demonstrate a strong correlation between yield strength and SCC susceptibility of A-286 in PWR primary water at 320 and 360 C. (author)

  5. Microbially influenced corrosion of stainless steels by aerobic bacteria; Kokisei saikin no kanyoshita sutenresu ko no biseibutsu fushoku

    Energy Technology Data Exchange (ETDEWEB)

    Amaya, H.; Miyuki, H. [Sumitomo Metal Inductries Ltd., Osaka (Japan). Corporate Research and Development Lab.

    1996-03-20

    Influence of microorganisms on the corrosion of metals has been recognized since Kuhr proposed the hypothesis of corrosion promotion due to so called hydrogen double electrode when hydrogen formed in corrosion reaction of steel is used by anaerobic bacteria. Corrosion of metals caused by the influence of such type of microorganisms is known as Microbially influenced corrosion (MIC), and recently is paid attention specially in Europe and America. These recent years, research on MIC is showing active trend even in Japan. As for the research subjects of MIC, the example of corrosion promotion of carbon steel by sulfate reducing bacteria (SRB) in anaerobic environment is paid attention conventionally. Further, at present, effect of general type of aerobic heterotrophic bacteria on the corrosion of steel is paid attention and research is carried out actively. In this report, effect of aerobic heterotrophic bacteria on the corrosion of stainless steel is introduced focusing to the authors knowhow regarding the ennoblement phenomena of corrosion potential of stainless steel in natural sea water. 44 refs., 10 figs., 3 tabs.

  6. 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.

  7. Microbial influenced corrosion of stainless steels in natural waters: interest of an enzymatic approach

    International Nuclear Information System (INIS)

    The electrochemical behavior of stainless steels in natural waters has been characterized with the ennoblement of their free corrosion potential (Ecorr). This phenomenon is heavily related to the bio-film settlement on their surfaces. Many hypotheses have been suggested to make clear the bio-film action. These hypotheses can be classified in two categories: mechanisms due to the passive film change and mechanisms related to the bio-film species. In these hypotheses, the enzymatic catalysis can play an important role by shifting the cathodic process. The catalytic effect of the bio-film has been reported by numerous researchers; however the enzyme use in experiments remains rare. This can be explained by two principal reasons: 1- Corrosion tests with the use of enzymes may cause some experimental problems. These proteins are sensible and can be denatured in the corresponding conditions. 2- Scientists, in microbial influenced corrosion, did not characterize enzymes which may play a role in corrosion; however some bacteria related to corrosion had been already identified. The 'corrosion enzymes' notions are unaware. Thus, the enzymatic approach still little reported in the literature. The aim of this paper is to show the interest of such approach to describe mechanisms implicated in the electrochemical behavior of stainless steels in natural waters. (authors)

  8. Microbial consortium influence upon steel corrosion rate, using polarisation resistance and electrochemical noise techniques

    International Nuclear Information System (INIS)

    The microbiologically influenced corrosion (MIC) is a process, which affects the oil industry, particularly the hydrocarbons extraction, transport and storage. MIC evaluation has been normally based upon microbiological tests, and just a few references mention alternating methods, such as the electrochemical techniques, which can be used as criteria for their evaluation. In this work, two different electrochemical laboratory techniques, polarisation resistance and electrochemical noise were used, in order to determine the corrosion behaviour of a microbial consortium, obtained from a gas transporting pipeline, located in the southeast of Mexico. The bacteria population growth was found to be different for sessile and plancktonic microorganisms. Moreover, long incubation times were required to reach the maximum concentration of sessile bacteria. The electrochemical techniques used in this study exhibited a similar tendency on the corrosion rate behaviour with time, and values above 0.3 mm year-1 were observed at the end of the experiments. The experiments were complemented with surface analysis. Scanning electron microscope observation of APIXL52 steel coupons, exposed to the consortium action, revealed bacteria presence, as well as a damaged steel surface. A type of localized corrosion was observed on the metal surface, and it was associated to the bacteria effect

  9. Influence of nitrogen in the shielding gas on corrosion resistance of duplex stainless steel welds

    Science.gov (United States)

    Bhatt, R. B.; Kamat, H. S.; Ghosal, S. K.; de, P. K.

    1999-10-01

    The influence of nitrogen in shielding gas on the corrosion resistance of welds of a duplex stainless steel (grade U-50), obtained by gas tungsten arc (GTA) with filler wire, autogenous GTA (bead-on-plate), electron beam welding (EBW), and microplasma techniques, has been evaluated in chloride solutions at 30 °C. Pitting attack has been observed in GTA, electron beam welding, and microplasma welds when welding has been carried out using pure argon as the shielding gas. Gas tungsten arc welding with 5 to 10% nitrogen and 90 to 95% argon, as the shielding gas, has been found to result in an improved pitting corrosion resistance of the weldments of this steel. However, the resistance to pitting of autogenous welds (bead-on-plate) obtained in pure argon as the shielding gas has been observed to remain unaffected. Microscopic examination, electron probe microanalysis (EPMA), and x-ray diffraction studies have revealed that the presence of nitrogen in the shielding gas in the GTA welds not only modifies the microstructure and the austenite to ferrite ratio but also results in a nearly uniform distribution of the various alloying elements, for example, chromium, nickel, and molybdenum among the constitutent phases, which are responsible for improved resistance to pitting corrosion.

  10. Investigating the Influence of Six Sigma Implementation in Khorasan Steel Plant in Year 2011

    Directory of Open Access Journals (Sweden)

    Kamran Nourbakhsh

    2013-08-01

    Full Text Available The purpose of this empirical research is to investigate the influence of implementation Six Sigma project in commodity management unit in Khorasan steel plant in year 2011 to explore the main reasons of the defects in determining the purchase orders amount and inventory control to generate the improvement in the processes and also the profitability through decreasing the defects in the purchase orders amount and inventory control. The researchers regarding the requirement of an assessment in commodity management unit after establishing management information system, decided to scrutinize the unit and tried for implementing Six Sigma quality improvement project and applying five stages of Six Sigma (DMAIC and its techniques such as Project Prism, SIPOC Chart, Failure Mode and Effect Analysis (FMEA, Workflow Chart, Fishbone Chart or Cause and Effect Analysis, Histogram, Process Capability ratio (CPK and using tools like Minitab and Sigma Calculator, examining the Sigma level for finding the reasons of the defects in determining the purchase orders amount and inventory control. Finally, the critical points that have significant effects on decreasing the deviation in the process were found and solutions for improving the process and decreasing the defects for commodity management unit of khorasan steel plant were provided.

  11. Microbial consortium influence upon steel corrosion rate, using polarisation resistance and electrochemical noise techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez Gayosso, M.J.; Zavala Olivares, G.; Ruiz Ordaz, N.; Juarez Ramirez, C.; Garcia Esquivel, R.; Padilla Viveros, A

    2004-10-01

    The microbiologically influenced corrosion (MIC) is a process, which affects the oil industry, particularly the hydrocarbons extraction, transport and storage. MIC evaluation has been normally based upon microbiological tests, and just a few references mention alternating methods, such as the electrochemical techniques, which can be used as criteria for their evaluation. In this work, two different electrochemical laboratory techniques, polarisation resistance and electrochemical noise were used, in order to determine the corrosion behaviour of a microbial consortium, obtained from a gas transporting pipeline, located in the southeast of Mexico. The bacteria population growth was found to be different for sessile and plancktonic microorganisms. Moreover, long incubation times were required to reach the maximum concentration of sessile bacteria. The electrochemical techniques used in this study exhibited a similar tendency on the corrosion rate behaviour with time, and values above 0.3 mm year{sup -1} were observed at the end of the experiments. The experiments were complemented with surface analysis. Scanning electron microscope observation of APIXL52 steel coupons, exposed to the consortium action, revealed bacteria presence, as well as a damaged steel surface. A type of localized corrosion was observed on the metal surface, and it was associated to the bacteria effect.

  12. Normalizing treatment influence on the forged steel SAE 8620 fracture properties

    Directory of Open Access Journals (Sweden)

    Paulo de Tarso Vida Gomes

    2005-03-01

    Full Text Available In a PWR nuclear power plant, the reactor pressure vessel (RPV contains the fuel assemblies and reactor vessels internals and keeps the coolant at high temperature and high pressure during normal operation. The RPV integrity must be assured all along its useful life to protect the general public against a significant radiation liberation damage. One of the critical issues relative to the VPR structural integrity refers to the pressurized thermal shock (PTS accident evaluation. To better understand the effects of this kind of event, a PTS experiment has been planned using an RPV prototype. The RPV material fracture behavior characterization in the ductile-brittle transition region represents one of the most important aspects of the structural assessment process of RPV's under PTS. This work presents the results of fracture toughness tests carried out to characterize the RPV prototype material behavior. The test data includes Charpy energy curves, T0 reference temperatures for definition of master curves, and fracture surfaces observed in electronic microscope. The results are given for the vessel steel in the "as received" and normalized conditions. This way, the influence of the normalizing treatment on the fracture properties of the steel could be evaluated.

  13. The influence of implanted yttrium on the cyclic oxidation behaviour of 304 stainless steel

    International Nuclear Information System (INIS)

    High-temperature alloys are frequently used in power plants, gasification systems, petrochemical industry, combustion processes and in aerospace applications. Depending on the application, materials are subjected to corrosive atmospheres and thermal cycling. In the present work, thermal cycling was carried out in order to study the influence of implanted yttrium on the oxide scale adherence on 304 steel specimens oxidised in air at 1273 K. In situ X-ray diffraction indicates that the oxides formed at 1273 K are different on blank specimens compared to implanted specimens. Glancing angle XRD allows to analyse the oxide scale composition after cooling to room temperature. Experimental results show that yttrium implantation at a nominal dose of 1017 ions cm-2 does not improve significantly the cyclic oxidation behaviour of the austenitic AISI 304 steel. However, it appears that yttrium implantation remarkably enhance the oxidation resistance during isothermal oxidation. It reduces the transient oxidation stage and the parabolic oxidation rate constant by one order of magnitude

  14. Influence of Processing Parameters on the Mechanical Properties of a Plasma Radical Nitrided SCM440 Steel

    Institute of Scientific and Technical Information of China (English)

    Seok-Hwan Ahn; Insup Lee

    2008-01-01

    Plasma radical nitriding was performed to harden the surface of SCM440 steel for 1-10 h at temperature range of 450-550℃. This process involved the use of NH3 gas instead of N2 gas employed for the well-established plasma nitriding method. No compound layer was formed during this process except the experiment carried out at 500℃ for 10 h. The main phase produced in the diffusion zone was identified to be γ'-Fe4(N, C). A diffusion depth increased with increasing treatment temperature and time (up to about 250 μm). The surface hardness of radical nitrided layer was about two times higher than that of the untreated surface. The tensile test was carried out to estimate the mechanical properties of surface-hardened SCM440 steel prepared at various plasma radical nitriding treatment time and temperature. The influence of radical nitriding treatment on the tensile strength of the specimen was found to be insignificant. The highest value of the ultimate tensile strength was obtained in the experiment carried out at 500℃ for 1 h. However, the elongation was greatly affected by the radical nitriding processing parameters. The maximum value of elongation, which is equal to about 18.1%, was also obtained under the condition of 500℃ for 1 h.

  15. 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.

  16. Microbial corrosion of steel in Toarcian argillite: potential influence of bio-films

    International Nuclear Information System (INIS)

    sulfate reduction. Then, the characterization of biodiversity of Tournemire argillite has shown the presence of bacteria within undisturbed argillite, as well as the potential development of exogenous microorganisms within disturbed areas. Indeed, the observed bacterial diversity tends to depend on the different oxygen and humidity conditions, and also probably on space availability. Furthermore, the interaction of argillite with steel coupons placed into boreholes filled with re-compacted argillite during 6 years has been described by Gaudin et al. (2009). This study highlighted that oxygen introduced in the boreholes during drilling was consumed slower than expected, but the presence of hematite tends to show that reducing conditions prevailing in the host rock may have been recovered within 6 years. Recently, the characterization of the microbial diversity at interfaces between steel coupons and argillite in similar boreholes after 10 years of interaction has been investigated. The bio-diversities differ depending on the steel type and the borehole considered, indicating the influence of both iron-clay interactions and in situ environmental conditions. Sulphate-reducing bacteria, iron-reducing bacteria and bacteria capable to develop at high temperatures were detected. These microorganisms can grow at the interfaces between materials in a very short period of time compared with planned durations of disposal. Experimental In this framework, in order to better understand the conditions favoring the formation of biofilm, as well as the impact of microorganisms on the durability of metallic components, an experimental methodology was designed to assess microbial corrosion of steel in contact with argillite. A synthetic solution representative of the Tournemire pore water percolates through cells containing steel coupons placed in contact with argillite. Various environmental conditions likely to prevail in a repository are tested. Different artificial communities of

  17. Investigation on the influence of flux density on RPV steel embrittlement

    International Nuclear Information System (INIS)

    Recent US results from surveillance programs indicate an influence of flux density on transition temperature shift induced by fast neutron irradiation. Own irradiation experiments on ASTM A533 gr B cl 1 steel from HSST plate 03 have been reevaluated but no flux density could be found. Taking into account the maximum experimental error upper limits have been estimated for the constants describing annealing according to simple models; corresponding ΔTT versus fluence curves for different flux densities have been calculated. To prove the assumptions and to better quantify the estimated constants an irradation experiment is being prepared in which the neutron flux density and the target fluence will be varied. The materials to be investigated are heats of 20MnMoNi55 and 22NiMoCr37 and corresponding weld material. (orig./HP)

  18. Influence of Post Weld Heat Treatment on the HAZ of Low Alloy Steel Weldments

    Directory of Open Access Journals (Sweden)

    S. Rasool Mohideen

    2010-06-01

    Full Text Available The heterogeneous nature of weldments demands an additional processing to retain and/or improve the joint properties. Heat Affected Zone, the zone Adjacent to the weld metal zone is critically affected by the sudden dissipation of heat from weld metal during welding. Toughness of this zone becomes weak as the grains get coarsened and the interface between the two regions is more prone to fracture. Post weld heat treatment is thus generally carried out on the weldments to relive the thermal residual stresses and to enhance the properties of welded joints. This paper discusses about the influence of post weld heat treatment on the fracture toughness of low alloy steel weldments. Fracture toughness of heat treated weldments was determined using standard CTOD test and the results were correlated.

  19. Shock imprint and rolling direction influence upon the breaking tenacity for 2P armor steel

    Science.gov (United States)

    Zichil, V.; Coseru, A.; Schnakovszky, C.; Herghelegiu, E.; Radu, C.

    2016-08-01

    The state of art in present literature shows that the breaking tenacity of a material is influenced by the integrity of the structure. Since armors used in aviation and to protect military vehicles are frequently impact loaded, through the contact between armor sheet and projectiles, or other foreign bodies, the authors have proposed to study the dependence between the breaking tenacity of 2P armor steel depending on the direction of the rolling of the armor plate, of the geometry (spherical imprint, pyramidal and linear imprint) and the depth of the deformation that results after impact. Tests were conducted upon CT (ASTM E- 399) specimen type, using the critical factor of stress intensity during the state of planar strain.

  20. Microbial consortium influence upon steel corrosion rate, using the electrochemical impedance spectroscopy technique

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Gayosso, M.J.; Ruiz-Ordaz, N. [Escuela Nacional de Ciencias Biologicas, Instituto Politecnico Nacional. Prolongacion de Carpio y Plan de Ayala, Mexico, D.F, C.P. 11340 (Mexico); Zavala-Olivares, G.; Garcia-Esquivel, R. [Instituto Mexicano del Petroleo, Grupo de Corrosion. Eje Central Lazaro Cardenas 152, Col. San Bartolo Atepehuacan, Mexico, D.F, C.P. 07730 (Mexico); Mora-Mendoza, J.L. [Petroleos Mexicanos, Marina Nacional 329, B-1, piso 8, Colonia Huasteca, CP 11311, Mexico, D.F. (Mexico)

    2004-09-01

    The Electrochemical Impedance Technique was used to evaluate the influence of a microbial consortium, isolated from a gas pipeline, upon API XL52 steel corrosion rate. The bacteria growth exhibited two different kinetics behavior, one for the planktonic and the other for the sessile phase. The sessile bacteria were found to be the main responsible for the corrosion rate increment observed during the experiments and no relationship between the planktonic microorganisms and the corrosion rate increment was found. The diagrams obtained from the electrochemical impedance measurements, indicated a biofilm formation and that the system changed from activation to diffusion control. Although the system was under diffusion control, an increment on the corrosion rate was detected, and a localized corrosion process was induced. The results were complemented with some surface analysis using Scanning Electron Microscopy. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  1. Simulating microbiologically influenced corrosion by depositing extracellular biopolymers on mild steel surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Roe, F.L.; Lewandowski, Z.; Funk, T. [Montana State Univ., Bozeman, MT (United States). Center for Biofilm Engineering

    1996-10-01

    Electrochemical properties of corroding mild steel (MS) surfaces were measured in real time using three closely spaced microelectrodes. Dissolved oxygen, pH, and ion currents were mapped simultaneously and noninvasively above a MS coupon partially coated with biopolymer gels. Calcium alginate (Ca-Alg [an extracellular biopolymer containing carboxylate functional groups]) and agarose (one without carboxylate functional groups) were tested. Corrosion occurred at approximately the same rate under the two biopolymer spots on the same coupon. Corrosion rates under these biopolymers were {approx} 4 mpy in a weak saline solution. Results suggested corrosion was not influenced by chemical properties of the biopolymer but possibly was controlled by oxygen reduction in noncoated regions of the coupon (i.e., a differential aeration cell).

  2. The influence of processing on the cryogenic mechanical properties of high strength high manganese stainless steel

    International Nuclear Information System (INIS)

    This paper describes the influence of the hot rolling condition and cold rolling on the mechanical properties of a nitrogen-strengthened high manganese steel of nominal composition 18Mn-5Ni-16Cr-0.02C-0.22N. The results show that grain refinement by low temperature hot rolling raises the strength of the alloy but decreases the toughness rapidly. Cold rolling at room temperature is an effective way to raise the strength without rapid deterioration of the toughness. Changing the hot rolling condition did not affect the fatigue crack growth rates, but the decrease in the fatigue crack growth rates was observed for cold rolled plates. This improvement in fatigue resistance might be attributed to the improvement of ductility through the suppression of the formation of the epsilon phase

  3. Influence of thermal history on corrosion resistance of duplex stainless steel linepipe

    International Nuclear Information System (INIS)

    Using NK CR22 duplex stainless steel 22%Cr-5.5%Ni-3%Mo, research has been carried out to analyze the influence of various thermal cycles on corrosion resistance. Special attention was paid to resistance to pitting corrosion in the weld heat affected zone (HAZ). The optimum range of welding heat input exists for the improvement of pitting corrosion resistance in the HAZ. Lower heat input brings about the deterioration of the resistance near the fusion line, higher one on the contrary degrades the HAZ apart from the fusion line. Both these phenomena are closely related to the sensitization of grain boundaries caused by the precipitation of chromium nitrides. Solution annealing is effective in giving pitting resistance in the HAZ. Annealing at temperatures over 11000C, increases susceptibility by sensitization of ferrite boundaries

  4. Analysis of laser cutting speed influence on the surface quality and shape deviation of steel parts

    Science.gov (United States)

    Kowalczyk, R.; Zebala, W.

    2014-11-01

    The results of laser cutting speed influence on the quality of machined surface, defined by the Ra roughness parameter and the shape errors, in case of machining two types of steel: i) P265GH, ii) 1.4307 are presented in the paper. Two CO2 laser cutters with maximum power of the laser beam 4000W and 3200W were used for the investigation. The characteristics of the roughness parameter Ra depending on the laser cutting speed vc are presented. The diagrams of shape deviation of the machined specimens for the greatest and lowest values of the Ra for the both laser cutters are also presented. The deviation values from the theoretical profile of the particular samples, taking into account the type of the cut-out shape profiles (circular, linear) are calculated.

  5. Influence of high deformation on the microstructure of low-carbon steel

    Institute of Scientific and Technical Information of China (English)

    Florin Popa; Ionel Chicina; Dan Frunz; Ioan Nicodim; Dorel Banabic

    2014-01-01

    Low-carbon steel sheets DC04 used in the automotive industry were subjected to cold rolling for thickness reduction from 20%to 89%. The desired thickness was achieved by successive reductions using a rolling mill. The influence of thickness reduction on the micro-structure was studied by scanning electron microscopy. Microstructure evolution was characterized by the distortion of grains and the occur-rence of the oriented grain structure for high cold work. A mechanism of grain restructuring for high cold work was described. The occur-rence of voids was discussed in relation with cold work. The evolution of voids at the grain boundaries and inside the grains was also consid-ered. To characterize the grain size, the Feret diameter was measured and the grain size distribution versus cold work was discussed. The chemical homogeneity of the sample was also analyzed.

  6. Influence of water cavitation peening with aeration on fatigue behaviour of SAE1045 steel

    Science.gov (United States)

    Han, B.; Ju, D. Y.; Jia, W. P.

    2007-10-01

    Water cavitation peening (WCP) with aeration is a recent potential method in the surface enhancement techniques. In this method, a ventilation nozzle is adopted to improve the process capability of WCP by increasing the impact pressure, which is induced by the bubble collapse on the surface of components in the similar way as conventional shot peening. In this paper, fatigue tests were conducted on the both-edge-notched flat tensile specimens to assess the influences of WCP on fatigue behaviour of SAE1045 steel. The notched specimens were treated by WCP, and the compressive residual stress distributions in the superficial layer were measured by X-ray diffraction method. The tension-tension ( R = Smin/ Smax = 0.1, f = 10 Hz) fatigue tests and the fracture surfaces observation by scan electron microscopy (SEM) were conducted. The experimental results show that WCP can improve the fatigue life by inducing the residual compressive stress in the superficial layer of mechanical components.

  7. The Influence of Heat Treatment on the Microstructure and Machinability of a Prehardened Mold Steel

    Science.gov (United States)

    Hoseiny, Hamed; Caballero, Francisca G.; M'Saoubi, Rachid; Högman, Berne; Weidow, Jonathan; Andrén, Hans-Olof

    2015-05-01

    The machinability performance of a modified AISI P20 steel, heat treated to have the same hardness but three different microstructures, lower bainite, tempered martensite, and primary spheroidized carbides in a tempered martensite matrix, was studied. The microstructures were characterized using light optical and scanning electron microscopy and X-ray diffraction, and mechanical properties were compared by means of tensile and Charpy V-notch impact tests. The influence of microstructure and the resultant mechanical properties on machinability was studied in the context of single tooth end milling operation. The results showed that the material containing primary spheroidized carbides exhibited a superior machinability at the expense of a marginal loss of tensile strength and impact toughness, with comparable yield strength to that of the material containing tempered martensite. By contrast, the material with bainitic microstructure showed the lowest yield strength and the poorest machinability performance while having the highest uniform elongation.

  8. Influence of water cavitation peening with aeration on fatigue behaviour of SAE1045 steel

    International Nuclear Information System (INIS)

    Water cavitation peening (WCP) with aeration is a recent potential method in the surface enhancement techniques. In this method, a ventilation nozzle is adopted to improve the process capability of WCP by increasing the impact pressure, which is induced by the bubble collapse on the surface of components in the similar way as conventional shot peening. In this paper, fatigue tests were conducted on the both-edge-notched flat tensile specimens to assess the influences of WCP on fatigue behaviour of SAE1045 steel. The notched specimens were treated by WCP, and the compressive residual stress distributions in the superficial layer were measured by X-ray diffraction method. The tension-tension (R = Smin/Smax = 0.1, f = 10 Hz) fatigue tests and the fracture surfaces observation by scan electron microscopy (SEM) were conducted. The experimental results show that WCP can improve the fatigue life by inducing the residual compressive stress in the superficial layer of mechanical components

  9. 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.

  10. Microbially influenced corrosion of stainless steel by marine bacterium Vibrio natriegens: (I) Corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Sha; Tian Jintao [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Chen Shougang, E-mail: sgchen@ouc.edu.cn [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Lei Yanhua; Chang Xueting; Liu Tao [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Yin Yansheng, E-mail: yys2006@ouc.edu.cn [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China)

    2009-04-30

    The microbially influenced corrosion of stainless steel (SS) by marine bacterium Vibrio natriegens (V. natriegens) was investigated using surface analysis (atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDXA)) and electrochemical techniques (the open circuit potential, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization curves ). AFM images corroborated the results from the EIS models which show biofilm attachment and subsequent detachment over time. The SEM images revealed the occurrence of micro-pitting corrosion underneath the biofilms on the metal surface after the biofilm removal. The presence of carbon, oxygen, phosphor and sulfur obtained from EDXA proved the formation of biofilm. The electrochemical results showed that the corrosion of SS was accelerated in the presence of V. natriegens based on the decrease in the resistance of the charge transfer resistance (R{sub ct}) obtained from EIS and the increase in corrosion current densities obtained from potentiodynamic polarization curves.

  11. Influence of zirconium on microstructure and toughness of low-alloy steel weld metals

    Science.gov (United States)

    Trindade, V. B.; Mello, R. S. T.; Payão, J. C.; Paranhos, R. P. R.

    2006-06-01

    The influence of zirconium on microstructure and toughness of low-alloy steel weld metal was studied. Weld metals with different zirconium contents were obtained adding iron-zirconium alloy in the welding flux formulation. Weld metal chemical composition proved that zirconium was able to be transferred from the flux to the weld metal. The addition of zirconium refined the weld metal microstructure, increasing the acicular ferrite content. Weld metal toughness, determined by means of impact Charpy-V tests, showed that the zirconium addition is beneficial up to a content of 0.005 wt.%. Above this level, zirconium was not able to produce further microstructure refinement, although the toughness was reduced, possibly due to the formation of microconstituent such as the martensite-austenite constituent (M-A), which is considered to be deleterious to the weld metal toughness.

  12. Influence of uniaxial, biaxial and plane strain pre-straining on the dynamic tensile properties of high strength sheet steels

    Science.gov (United States)

    Larour, P.; Verleysen, P.; Bleck, W.

    2006-08-01

    The influence of pre-straining and microstructure on the dynamic properties of car body high strength steels has been investigated at room temperature. The mechanical properties of a dual phase steel DP600, a TRIP steel TRIP700 and an austenitic steel AISI 301LN2B (1.4318) have been determined performing high speed servohydraulic and split-Hopkinson bar tensile tests in the strain rate range from 0.005s-1 up to 950s-1. The pre-straining modes and levels, respectively 10% uniaxial, 10% plane strain and 5% biaxial pre-straining, have been chosen in this investigation according to industrial use. 10% plane strain pre-straining brings the highest increase of yield and tensile strength values. 5% biaxial and 10% uniaxial pre-straining have similar effect on strength properties. The austenitic steel presents a pronounced minimum for tensile strength values at around 1/s. A combination of adiabatic heating and exothermic γ to α' transformation produces some significant softening effects in the austenitic steel grade.

  13. The influence of composition of heat affected zone toughness of C-Mn microalloyed steels

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, A.M.; Hart, P.H.M. [TWI, Cambridge (United Kingdom). Materials Dept.

    1996-12-01

    Bead-in-groove welds made at an arc energy of 2.4 kJ/mm in nineteen experimental steel casts, were made to study the influence of variations in C, Mn, P, Si, Nb, V, Al, and N. To facilitate study of the ICGCHAZ an intercritical thermal cycle was applied using a weld thermal simulator. Fracture toughness testing was subsequently carried out, accompanied by microstructural characterization, hardness testing and fractography. For the conditions studied, lowest toughness was consistently recorded for the as-welded ICGCHAZ, but for both the GC and ICGC HAZ regions, toughness was improved by PWHT. For the as-welded GCHAZ, increases in element concentration and carbon equivalent, generally led to reduced toughness, although increased Al and V (without Nb) were found to be beneficial. The trends were similar following PWHT, but only increases in Al were found to be beneficial. The as-welded ICGCHAZ toughness generally decreased as element concentrations were increased; the effect of each element was generally quite weak, although a powerful effect of Mn was recorded. In the PWHT condition the toughness was again reduced by increases in element concentration, but in this instance no influence of Mn was detected, and the overall toughness was similar to that of the PWHT GCHAZ. The quantitative data presented should assist in the design of steel compositions for improved toughness through the use of those data for elements appropriate to specific production routes. Of particular importance is the variation in elemental effects on whether the final application will be in the as-welded or stress relieved condition.

  14. Influence of tellurium sulfides` morphology and workability of constructional steel; Wplyw telluru na morfologie siarczkow i skrawalnosc stali konstrukcyjnej

    Energy Technology Data Exchange (ETDEWEB)

    Pytel, S.M.; Kadluczka, A.M. [Instytut Materialoznawstwa i Technologii Metali, Politechnika Krakowska, Cracow (Poland)

    1995-12-31

    The interactions of the tellurium additions on quantitative changes in sulfur geometry as well as the influence of such changes on workability improvement of low-alloyed construction steel have been investigated and discussed. (author). 7 refs, 3 figs, 2 tabs.

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

    International Nuclear Information System (INIS)

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

  16. Evaluation of radiation hardening in ion-irradiated Fe based alloys by nanoindentation

    International Nuclear Information System (INIS)

    Nanoindentation in combination with ion irradiation offers the possibility to quantify irradiation hardening due to radiation damage. Irradiation experiments for Fe–1.0wt.%Cu alloys, China A508-3 steels, and 16MND5 steels were carried out at about 100 °C by proton and Fe-ions with the energy of 240 keV, 3 MeV respectively. The constant stiffness measurement (CSM) with a diamond Berkovich indenter was used to obtain the depth profile of hardness. The results showed that under 240 keV proton irradiation (peak damage up to 0.5 dpa), Fe–1.0wt.%Cu alloys exhibited the largest hardening (∼55%), 16MND5 steels resided in medium hardening (∼46%), and China A508-3(2) steels had the least hardening (∼10%). Under 3 MeV Fe ions irradiation (peak damage up to 1.37 dpa), both China A508-3(1) and 16MND5 steels showed the same hardening (∼26%). The sequence of irradiation tolerance for these materials is China A508-3(2) > 16MND5 ≈ China A508-3(1) > Fe–1.0wt.%Cu. Based on the determination of the transition depth, the nominal hardness H0irr was also calculated by Kasada method

  17. Influence of Molybdenum Addition on Mechanical Properties of Low Carbon HSLA-100 Steel

    OpenAIRE

    Bogucki R.; Pytel S.M.

    2014-01-01

    The results of mechanical properties and microstructure observation of low carbon copper bearing steel with high addition of molybdenum are presented in this paper. This steels were characterized by contents of molybdenum in the range from 1% to 3% wt. After the thermo -mechanical processing the steels were subsequently quenched and tempered at different temperatures (500-800 °C) for 1h. The changes of mechanical properties as function of tempering temperature were typical for the steel with ...

  18. Studing the Influence of Six Main Industrial Losses on Overall Equipment Effectiveness in Cold Rolling Unit of Mobarakeh Steel Complex

    Directory of Open Access Journals (Sweden)

    seyed Akbar Nilipour Tabatabaei

    2011-03-01

    Full Text Available Overall Equipment Effectiveness (OEE is a key indicator and a basis for evaluating the effectiveness of equipments as well as assessing the effectiveness of the Total Productive Maintenance (TPM system. This indicator together with overall equipment performance can be used in production lines such as steel production. The aim of this article is to study the influence of six main industrial losses on the OEE indicator . For this purpose, the OEE has been calculated in the cold rolling production lines of Mobarakeh Steel Complex the gap between production lines and the global industrial standards has been studied the causes of production system inefficiency has been investigated and the effectiveness of TPM system, equipments' bottlenecks and the influence of the main industry losses on OEE have been studied. The findings imply that the influence of the variation of availability and performance rates on OEE is high, while the influence of the variation of quality rate on OEE is not considerable.

  19. Significance and influence of the ambient temperature as a rate factor of steel reinforcement corrosion

    Indian Academy of Sciences (India)

    V Živica

    2002-10-01

    The rate of corrosion of reinforcement being an electrochemical process, undoubtedly is dependent even on the level of the ambient temperature. Therefore, the ambient temperature seems to be an important factor of the corrosion rate and the durability of the reinforced concrete structures in aggressive environment. The present data on the influence and significance of the ambient temperature in the process of corrosion of reinforcement of the reinforced structures are surprisingly limited and poor. It seems that it is supposed to be a simple increase of corrosion rate when the ambient temperature is increased. The lack of information was a motivation for the present study. It was aimed at the experimental research of the influence of the increase of the ambient temperature on the rate of chloride induced corrosion of steel reinforcement. The results obtained show that the influence of the studied factor is more complex showing an acceleration effect till a temperature of 40°C diversified by the inhibition effects with further increase of the ambient temperature.

  20. Influence of the Microstructure of the Corrosion Performance of DP Steels

    NARCIS (Netherlands)

    Farias Moreno, D.E.

    2014-01-01

    Weight reduction of car bodies can be achieved by application of steel components with a lower thickness; however mechanical properties (for constructive and safety reasons) must be maintained, which can be achieved by using (U)HSS steels. These steels have been designed and optimized for improved m

  1. 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,

  2. Influence of Plastic Deformation on Low Temperature Surface Hardening of Austenitic and Precipitation Hardening Stainless Steels by Gaseous Nitriding

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas Lundin;

    2015-01-01

    This article addresses an investigation of the influence of plastic deformation on low temperature surface hardening by gaseous nitriding of three commercial austenitic stainless steels: AISI 304, EN 1.4369 and Sandvik Nanoflex® with various degrees of austenite stability. The materials were...... case included X-ray diffraction analysis, reflected light microscopy and microhardness. The results demonstrate that a case of expanded austenite develops and that, in particular, strain-induced martensite has a large influence on the nitrided zone....

  3. Influence of plastic deformation on CCT-diagrams of low-carbon and medium-carbon TRIP-steels

    Directory of Open Access Journals (Sweden)

    M. Opiela

    2008-07-01

    Full Text Available Purpose: The aim of the paper is to investigate the influence of plastic deformation and cooling conditions on a structure and a shape of CCT-diagrams of new-developed TRIP-aided microalloyed steels.Design/methodology/approach: The diagrams of undeformed and plastically-deformed supercooled austenite transformations for low-carbon and medium-carbon microalloyed steels were determined. A part of the specimens were austenitized at a temperature of 1100°C, then slowly cooled to 900°C and next cooled to ambient temperature with a various rate from 1 to 300°C/s. To investigate the influence of plastic deformation on a shape of CCT (Continuous Cooling Transformations diagrams, another part of the specimens were 50% deformed at 900°C and cooled to ambient temperature with a rate from 88 to 1°C/s. The DIL805A/D dilatometer, with a LVDT-type measuring head, was used to carry out dilatometric tests.Findings: It was found that a shape of CCT diagrams of elaborated steels predisposes them for multiphase sheets manufacturing. The new-developed steels possess ferritic and bainitic bays put forward to short times and pearlitic regions put aside. However, cooling the steel with a constant rate from austenitizing temperature doesn’t lead to obtaining proper participation of ferrite. Plastic deformation of steel has a profitable influence on the shape of supercooled austenite curves. The region of γ→α transformation is translated to the left at simultaneous raise of start temperature of austenite into ferrite transformation resulting in definitely higher ferrite fraction. Moreover, significant refinement of microstructure in a whole range of cooling rate was also obtained.Research limitations/implications: To increase the ferrite fraction, modification of the cooling after hot-working finishing should be applied. In the fist stage, steel should be rapidly cooled in order to enter the range of γ→α transformation and successively slowly cooled in a

  4. Study of Corrosion Behavior of a 2507 Super Duplex Stainless Steel : Influence of Quenched-in and Isothermal Nitrides

    OpenAIRE

    Bettini, Eleonora; Kivisäkk, Ulf; Leygraf, Christofer; Pan, Jinshan

    2014-01-01

    Precipitation of different types of chromium nitrides may occur during processing of super duplex stainless steels, affecting the properties of the material. In this study the influence of quenched-in (size range ca. 50-100 nm) and isothermal (size range ca. 80-250 nm) types of nitrides on the corrosion behavior of a 2507 super duplex stainless steel has been investigated at room temperature and at 90 degrees C (above the critical pitting temperature) in 1 M NaCl solution. The microstructure ...

  5. The influences of ultrasonic peening treatment on oxidization of designed F/M steels in supercritical water

    International Nuclear Information System (INIS)

    The influence of ultrasonic peening on oxidation of designed Ferritic/Martensitic (F/M) steels in supercritical water has been investigated with time range from 100 hours to 1000 hours. It was observed that in the tested time range, the weight gain of the samples with ultrasonic peening pre-treatment is much less than that of the ones without ultrasonic peening. Different oxide film formed on the surface after SCW exposure. These results indicate that designed F/M steels with ultrasonic peening have better oxidation resistant in 500°C, 25MPa supercritical water than the ones without ultrasonic peening. (author)

  6. Influence of some parameters on the stress corrosion of a ABNT 304 stainless steel in MgCl2

    International Nuclear Information System (INIS)

    The susceptibility to stress corrosion cracking of the austenitic stainless steel AISI 304 in MgCl, solution was studied. When changes on the surface film were produced like a prepassivation of the steel in HNO3 solution or chromate solution or even a previous cathodic reduction. A mixture of MgCl2 + NaCl was also used in such a way that the cation influence on the scc process could be analised. Results show that the surface film seems to have great importance in the see mechanism and that addition of Na+ ions inhibit cracks at the corrosion potencial. (Author)

  7. Use of Homogeneously-Sized Carbon Steel Ball Bearings to Study Microbially-Influenced Corrosion in Oil Field Samples

    OpenAIRE

    Gerrit eVoordouw; Priyesh eMenon; Tijan ePinnock; Mohita eSharma; Yin eShen; Amanda eVenturelli; Johanna eVoordouw; Aoife eSexton

    2016-01-01

    Microbially-influenced corrosion (MIC) contributes to the general corrosion rate (CR), which is typically measured with carbon steel coupons. Here we explore the use of carbon steel ball bearings, referred to as beads (55.0 ± 0.3 mg; Ø = 0.238 cm), for determining CRs. CRs for samples from an oil field in Oceania incubated with beads were determined by the weight loss method, using acid treatment to remove corrosion products. The release of ferrous and ferric iron was also measured and CRs ba...

  8. Microbiologically influenced corrosion of carbon steel from secondary circuit of nuclear power plant

    International Nuclear Information System (INIS)

    Microbiologically influenced corrosion (MIC) is the initiation or acceleration of the corrosion due to the interaction between the microbial activity and the corrosion processes. During 1980s , the electric power industry, particularly the nuclear industry , has devoted increased attention to MIC that affect reliability, operating and maintenance costs of plant systems. The economic impact of failures in such systems in large nuclear units can be extremely costly, about USD 1,000,000 per day. Costs for chemicals and delivery systems for water treatments to prevent MIC and biofouling can approach about USD 1,000,000 per year. Several plants have been forced to undertake replacement or to make extensive repairs of their service water system at a cost of about USD 30,000,000 per plant. Nuclear power plant can exhibit MIC as a result of their basic design philosophy. The large number of stand-by and redundant systems in nuclear plant design establishes stagnant or intermittent flow conditions, a situation in which a number of systems, some of which are safety-related, will be susceptible to MIC. The large size of nuclear generating facilities and the often prolonged licensing process has resulted in an extended construction phase, often with structural materials in contact with stagnant, untreated water used for hydrostat testing. This also produces a condition amenable to microbial growth. Carbon steels may experience random pitting, general corrosion, or severe degradation in flow as a result of MIC. Tubercles (comprising corrosion products, microbes, sticky exopolymer associated with both living and dead cells, and debris) often form on carbon steel pipes and other components. The tubercles create a hydraulic resistance to cooling water flow as well as sites for additional microbial activity. Tubercles can grow together, eventually becoming a severe impediment to cooling water flow. Pitting is also often observed beneath tubercles as mechanical and chemical

  9. Study of Influence of Heat Treatment on Cyclic Properties of L21HMF Cast Steel

    Science.gov (United States)

    Mroziński, Stanisław; Golański, Grzegorz

    2016-07-01

    This work presents the results of studies of CrMoV cast steel after long-term service and after regenerative heat treatment (RHT). The cast steel was investigated in the conditions of static and changeable load. The tests were carried out at room temperature and 550 °C. The fatigue lifetime curves were determined and described using the Basquin-Manson-Coffin relationship. It has been shown that the cast steel after RHT is characterized by smaller range of plastic strain and bigger range of stress amplitude, with the same value of total strain, compared with the cast steel after service. For the cast steel after RHT, the observed fatigue properties were different in comparison with the cast steel after service at small and large strains. At room temperature (20 °C) and at elevated temperature (550 °C), there is an increase in the life of samples of the cast steel after RHT in comparison with the samples of the cast steel after service only in the area of large strains ( ɛ ac > 1.2%). For small strains ɛ ac life of the cast steel after RHT at the examined temperatures is shorter than that of the cast steel after service. The paper shows that regardless of an explicit improvement in the strength properties (the static and cyclic ones), as a result of the performed RHT, a complete improvement in the fatigue properties of the cast steel does not occur.

  10. Influence of loading path on formability of 304 stainless steel tubes

    Institute of Scientific and Technical Information of China (English)

    ZHANG ShiHong; YUAN AnYing; WANG Bin; ZHANG HaiQu; WANG ZhongTang

    2009-01-01

    The loading path affects the metal formability remarkably in tube hydroforming,and it is also one of the research focuses.Recently,some scholars abroad proposed a new fluctuant hydraulic loading method,which can improve the formability of tubes in hydroforming.Related studies have shown that this new loading method can improve the tube formability,the distribution of deformation is more uniform and this is useful for avoiding excessive local thinning.In this paper,tube hydroforming experiments without axial feeding were carried out;the influences of the loading methods on formability of stainless steel tubes were studied.Through the comparison of the experimental results under the condition of monotonous increase loading and fluctuation hydraulic loading,the outside diameter distribution,the thickness distribution and the crack expansion forms of deformation zone all fully prove that the uniformity of the distribution of tube deformation and formability have been increased significantly under the condition of fluctuation loading without axial feeding,the reasons should be distinguished from the fluctuation hydroforming with axial feeding.In order to study the forming mechanism,uniaxial tensile test of tubes similar to fluctuation loading deformation is designed in this paper,namely intermittent tensile test.It is found that intermittent uniaxial stretch can improve the tube elongation at fracture by about 40% and the deformation distribution is more uniform than that through uniaxial tensile test of the stainless steel tube.In the process of intermittent tensile tests,changes of metal microstructures brought by the loading and unloading processes are the main reasons that improve the formability of the tubes.

  11. Influence of loading path on formability of 304 stainless steel tubes

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The loading path affects the metal formability remarkably in tube hydroforming, and it is also one of the research focuses. Recently, some scholars abroad proposed a new fluctuant hydraulic loading method, which can improve the formability of tubes in hydroforming. Related studies have shown that this new loading method can improve the tube formability, the distribution of deformation is more uniform and this is useful for avoiding excessive local thinning. In this paper, tube hydroforming experiments without axial feeding were carried out; the influences of the loading methods on formability of stainless steel tubes were studied. Through the comparison of the experimental results under the condition of monotonous increase loading and fluctuation hydraulic loading, the outside diameter distribution, the thickness distribution and the crack expansion forms of deformation zone all fully prove that the uniformity of the distribution of tube deformation and formability have been increased significantly under the condition of fluctuation loading without axial feeding, the reasons should be distinguished from the fluctuation hydroforming with axial feeding. In order to study the forming mechanism, uniaxial tensile test of tubes similar to fluctuation loading deformation is designed in this paper, namely intermittent tensile test. It is found that intermittent uniaxial stretch can improve the tube elongation at fracture by about 40% and the deformation distribution is more uniform than that through uniaxial tensile test of the stainless steel tube. In the process of intermittent tensile tests, changes of metal microstructures brought by the loading and unloading processes are the main reasons that improve the formability of the tubes.

  12. Influence of sodium on creep-rupture behaviour of type 304 stainless steel

    International Nuclear Information System (INIS)

    The influence of flowing liquid sodium at 550deg C on the creep-rupture behaviour of the structural material of the SNR 300 reactor, X6CrNi18 11 (DIN 1.4948, equivalent to Type 304 SS) was studied in two non-isothermal sodium loops. It was shown that the effects of sodium are dependent on the carbon activity of the sodium. Under normal (non-decarburizing) sodium conditions a limited reduction of times-to-rupture occurs. This reduction is due to a reduced ductility within the tertiary creep range. The minimum creep rate and the onset of tertiary creep are not influenced. Under decarburizing conditions, which are not expected to occur in the sodium of LMFBRS, an additional loss of creep strength was observed. The steel showed higher creep rates and an earlier onset of tertiary creep. This additional effect seems to be caused by sodium corrosion of surface-near layers reducing the unaffected cross section. It depends on the surface-to-volume ratio, and it was nearly suppressed, when thicker specimens (6 mm diameter) were used. (orig.)

  13. Research on key influence factors of laser overlap welding of automobile body galvanized steel

    Science.gov (United States)

    Chen, Genyu; Mei, Lifang; Zhang, Mingjun; Zhang, Yi; Wang, Zujian

    2013-02-01

    In views of structure characteristics of the auto-body parts, the influences of the beam incident angle and joint gap on the performance of laser overlap welded joints were investigated. The experimental results indicate that there were the critical values of beam incident angle and joint gap during laser overlap welding of galvanized steel. The thickness of sheet and the width of joint had a certain influence on the critical beam incident angle and the limit joint gap. With regard to thicker sheet, the limit joint gap can increase appropriately, but the critical beam incident angle should not be too big. With narrow weld width, the laser beam incident angle can increase appropriately, but the joint gap should not be bigger. Additionally, the critical beam incident angle and the limit joint gap were varied with the thickness of the upper sheet. The tensile-shear tests show that the maximum tensile-shear strength of the joint can be obtained with an optimized beam incident angle and joint gap.

  14. Influence of Martensite Fraction on the Stabilization of Austenite in Austenitic-Martensitic Stainless Steels

    Science.gov (United States)

    Huang, Qiuliang; De Cooman, Bruno C.; Biermann, Horst; Mola, Javad

    2016-05-01

    The influence of martensite fraction ( f α') on the stabilization of austenite was studied by quench interruption below M s temperature of an Fe-13Cr-0.31C (mass pct) stainless steel. The interval between the quench interruption temperature and the secondary martensite start temperature, denoted as θ, was used to quantify the extent of austenite stabilization. In experiments with and without a reheating step subsequent to quench interruption, the variation of θ with f α' showed a transition after transformation of almost half of the austenite. This trend was observed regardless of the solution annealing temperature which influenced the martensite start temperature. The transition in θ was ascribed to a change in the type of martensite nucleation sites from austenite grain and twin boundaries at low f α' to the faults near austenite-martensite (A-M) boundaries at high f α'. At low temperatures, the local carbon enrichment of such boundaries was responsible for the enhanced stabilization at high f α'. At high temperatures, relevant to the quenching and partitioning processing, on the other hand, the pronounced stabilization at high f α' was attributed to the uniform partitioning of the carbon stored at A-M boundaries into the austenite. Reduction in the fault density of austenite served as an auxiliary stabilization mechanism at high temperatures.

  15. Influence of the V microaddition on the structure and mechanical properties of 60CrV7 spring steel

    Directory of Open Access Journals (Sweden)

    M. Opiela

    2007-01-01

    Full Text Available Purpose: Influence of vanadium microaddition on structure and mechanical properties of the constructionalspring steel was investigated.Design/methodology/approach: Metallography, transmission electron microscope, tensile test, hardnessmeasurements have been used.Findings: Microaddition of V introduced to the steel allows to obtain the fine-grained structure, and gives elasticelements obtaining: apparent elastic limit Rp0.05 over 1800 MPa, proof stress Rp0.2 over 1900 MPa and ultimatetensile strength over 1960 MPa after tempering at 450 °C temperature.Research limitations/implications: TEM investigations on structure of the elastic elements after heat treatmentwere predicted.Practical implications: The carried out investigations showed a full suitability of the steel for production ofsprings and suspension springs witch high strength properties, operating under conditions of high elastic strains.Originality/value: Conditions of heat treatment of elastic elements with the high strength properties were presented.

  16. Influence of semi-solid isothermal treatment on eutectic carbide in Cr12MoV steel

    Directory of Open Access Journals (Sweden)

    Li Qingchun

    2014-11-01

    Full Text Available In-situ observation of eutectic solidification of Cr12MoV steel was conducted using high temperature confocal laser-scanning microscopy. The semi-solid isothermal treatment temperature of the steel was determined by thermodynamic calculation using Thermo-cal software. At the same time, the influences of isothermal treatment temperature and time on eutectic carbides in the steel were also studied. The results show that when the liquid metal cools at the rate of 47 °C·min-1, the eutectic reaction occurs rapidly at 1,214.7 °C in one second with the reticular liquid around austenite dendrites, transforming into a network of eutectic structure. After being held at 1,300 °C for 30 min, the carbide network is broken due to the impingement of refined primary austenite dendrites and secondary dendrites arms, and the thickness of eutectic structure is reduced.

  17. Influence of Al on the fatigue crack growth behavior of Fe–22Mn–(3Al)–0.6C TWIP steels

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Penghui [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004 (China); Qian, Lihe, E-mail: dlhqian@yahoo.com [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004 (China); Meng, Jiangying [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Liu, Shuai; Zhang, Fucheng [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004 (China)

    2015-10-01

    The influence of Al on fatigue crack growth (FCG) behavior of the high-Mn austenitic twinning-induced plasticity (TWIP) steel was investigated by conducting FCG tests on Fe–22Mn–0Al–0.6C and Fe–22Mn–3Al–0.6C TWIP steels (hereafter, referred to as 0Al and 3Al TWIP steel, respectively). The FCG tests were performed at stress ratio of 0.1 under the control of stress intensity factor range using three-point bending specimens. Excepting that the traditional two-dimensional (2D) observation methods (optical, scanning and transmission electron microscopes) were used to observe the crack paths, fracture surfaces and microstructure features, a high-resolution synchrotron X-ray computed tomography was also applied to observe the three-dimensional (3-D) crack morphology. The results indicate that the FCG resistance of the 0Al TWIP steel is superior to that of 3Al TWIP steel in the near threshold regime. Observed from the 2D crack paths and 3D crack morphologies, it can be found that the crack surface roughness and crack deflection of the 0Al steel are greater than those of 3Al steel. It is suggested that the degree of roughness-induced crack closure decreases with the addition of Al. And the 0Al steel shows much larger plastic zone sizes ahead of the crack tip than the 3Al steel, suggesting that plasticity-induced crack closure may also play an important role in decreasing the FCG rate in the 0Al steel. By excluding the crack closure effects, the 0Al steel still exhibits a higher effective crack growth threshold value than the 3Al steel; this is considered to be due to the higher planarity of slip in the 0Al steel than in the 3Al steel, and the mechanical twins generated in the 0Al steel reduce the stress concentration at crack tip.

  18. Influence of microstructure on the microbial corrosión behaviour of stainless steels

    Directory of Open Access Journals (Sweden)

    Moreno, Diego Alejandro

    2000-08-01

    Full Text Available Several stainless steels (Types UNS S30300, S30400, S30403, S31600, S31603 and S42000 with different microstructural characteristics have been used to study the influence of heat treatments on microbiologically influenced corrosion (MIC. Biocorrosion and accelerated electrochemical testing was performed in various microbiological media. Two species of sulphate-reducing bacteria (SRB have been used in order to ascertain the influence of microstructure. The morphology of corrosion pits produced in both chloride and chloride plus sulphide -SRB metabolites- was inspected by optical and scanning electron microscopy (SEM complemented with energy-dispersive X-ray (EDX analysis. Results have shown different behaviours regarding corrosion resistance in each case studied. Sensitized austenitic stainless steels were more affected by the presence of aggressive anions and pitting potential (Ep values were more cathodic than those of as-received state. A corrosion enhancement is produced by the synergistic action of biogenic sulphides and chloride anions. Pitting corrosion in martensitic stainless Steel Type UNS S42000 was found in a- biocorrosion test. The pitting morphology is correlated to the chemical composition, the microstructure and the electrolyte.

    Se han utilizado aceros inoxidables de los tipos UNS S30300, S30400, S30403, S31600, S31603 y S42000, en diferentes estados microestructurales, para estudiar la influencia de los tratamientos térmicos sobre la corrosión microbiana. Para ello, se han realizado ensayos electroquímicos y ensayos de biocorrosión, en diferentes medios microbiológicos, utilizándose dos especies de bacterias reductoras de sulfatos (SRB. La morfología de las picaduras, producidas en presencia de cloruros y en presencia de cloruros más sulfuros -metabolitos de SRB-, se ha analizado por microscopía óptica y por microscopía electrónica de barrido (SEM complementada con análisis por energía dispersiva de rayos X

  19. The influence of calcium on technological properties and micropurity of steel castings

    Directory of Open Access Journals (Sweden)

    J. Hampl

    2016-07-01

    Full Text Available The paper analyzes the technological parameters, micro-purity and mechanical properties of castings of steel alloyed with calcium. The effect of calcium on the steel was analyzed on samples taken in the process of casting heavy castings and ingots of the weight of ranging from 40 000 to 60 000 kg. Samples for the determination of the liquidus temperature and the solidus temperature of cast steels were analysed using differential thermal analysis (DTA. The production of low alloyed steel grades was performed on the EAF - ASEA-SKF facilities and the production of highalloyed steels on the EAF - ASEA-SKF - SS-VOD facilities. The purity calcium was added into the steel by the injection of a stuffed profile.

  20. Influence of Martensite Volume Fraction on Impact Properties of Triple Phase (TP) Steels

    Science.gov (United States)

    Zare, Ahmad; Ekrami, A.

    2013-03-01

    Ferrite-bainite-martensite triple phase (TP) microstructures with different volume fractions of martensite were obtained by changing heat treatment time during austempering at 300 °C. Room temperature impact properties of TP steels with different martensite volume fractions ( V M) were determined by means of Charpy impact testing. The effects of test temperature on impact properties were also investigated for two selected microstructures containing 0 (the DP steel) and 8.5 vol.% martensite. Test results showed reduction in toughness with increasing V M in TP steels. Fracture toughness values for the DP and TP steels with 8.5 vol.% martensite were obtained from correlation between fracture toughness and the Charpy impact energy. Fractography of Charpy specimens confirmed decrease in TP steels' toughness with increasing V M by considering and comparing radial marks and crack initiation regions at the fracture surfaces of the studied steels.

  1. The influence of sintering time on the properties of PM duplex stainless steel

    OpenAIRE

    Z. Brytan; L.A. Dobrzański; M. Actis Grande; M. Rosso

    2009-01-01

    Purpose: The purpose of this paper is to analyse the effect of sintering time on the pore morphology, microstructural changes, tensile properties and corrosion resistance of vacuum sintered duplex stainless steel.Design/methodology/approach: In presented study PM duplex stainless steels were obtained through mixing base ferritic stainless steel powder with controlled addition of elemental alloying powders and then sintered in a vacuum furnace with argon backfilling at 1250°C for different tim...

  2. Influence of grinding operations on surface integrity and chloride induced stress corrosion cracking of stainless steels

    OpenAIRE

    Zhou, Nian

    2016-01-01

    Stainless steels were developed in the early 20th century and are used where both the mechanical properties of steels and corrosion resistance are required. There is continuous research to allow stainless steel components to be produced in a more economical way and be used in more harsh environments. A necessary component in this effort is to correlate the service performance with the production processes. The central theme of this thesis is the mechanical grinding process.  This is commonly ...

  3. Influence of Tempering Temperature on Cyclic Viscoplastic Behaviour of 55NiCrMoV7 Steel

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhan-ping; DELAGNES Denis; BERNHART Gerard

    2004-01-01

    Low cycle fatigue behaviour of a steel 55NiCrMoV7 under four tempered conditions is reported. One special type of total strain controlled isothermal cyclic deformation tests were performed in the temperature range 20℃ to 600℃for the steel tempered 2h at 350℃, 460℃, 560℃ and 600℃. The influence of temperature on cyclic behaviour was investigated. Generally, the cyclic stress response shows an initial exponential softening for the first few cycles, followed by a gradual softening without cyclic softening saturation. At 10-2 strain rate, σmax. △σ/2 decrease with the test temperature for all hardness levels. They decrease linearly with tempering temperature when testing temperature is lower than that of tempering, but rest nearly constant when test temperature is equal to or exceed tempering temperature of steel. Cyclic softening intensity increases with testing temperature from 300℃ to 600℃, but the maximal softening intensity occurs at room temperature. The strain rate influences notably the cyclic behaviour when T≥500℃. The time dependence of cyclic behaviour is closely related to test temperature and the tempering history of the steel.

  4. Influence of the Magnetic High-speed Steel Cutting Tool on Cutting Capability

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The high-speed steel cutting tool has advantaged i n modern cutting tool for its preferable synthetical performance, especially, in a pplication of complicated cutting tools. Therefore, the study of the high-speed steel cutting tools that occupied half of cutting tools has become an importa nt way of studying on modern cutting technology. The cutting performance of hi gh speed-steel cutting tools will be improved by magnetization treating method. Microstructure of high-speed steel will be changed as a ...

  5. Efficiency of inhibitor for biocorrosion influenced by consortium sulfate reducing bacteria on carbon steel

    Science.gov (United States)

    Mahat, Nur Akma; Othman, Norinsan Kamil; Sahrani, Fathul Karim

    2015-09-01

    The inhibition efficiency of benzalkonium chloride (BKC) in controlling biocorrosion on the carbon steel surfaces has been investigated. The carbon steel coupons were incubated in the presence of consortium SRB (C-SRB) with and without BKC for the difference medium concentration. The corrosion rate and inhibition efficiency have been evaluated by a weight loss method. The morphology of biofilm C-SRB on the steel surfaces were characterized with variable pressure scanning electron microscopy (VPSEM). The results revealed that BKC exhibits a low corrosion rate, minimizing the cell growth and biofilm development on the carbon steel surfaces.

  6. Efficiency of inhibitor for biocorrosion influenced by consortium sulfate reducing bacteria on carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Mahat, Nur Akma; Othman, Norinsan Kamil [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Sahrani, Fathul Karim [School of Environment and Natural Resources Science, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

    2015-09-25

    The inhibition efficiency of benzalkonium chloride (BKC) in controlling biocorrosion on the carbon steel surfaces has been investigated. The carbon steel coupons were incubated in the presence of consortium SRB (C-SRB) with and without BKC for the difference medium concentration. The corrosion rate and inhibition efficiency have been evaluated by a weight loss method. The morphology of biofilm C-SRB on the steel surfaces were characterized with variable pressure scanning electron microscopy (VPSEM). The results revealed that BKC exhibits a low corrosion rate, minimizing the cell growth and biofilm development on the carbon steel surfaces.

  7. RESEARCH OF INFLUENCE OF THE HIGH-SPEED THERMAL PROCESSING REGIMES ON STRUCTURE AND MECHANICAL PROPERTIES OF PIPE STEEL 32G2

    Directory of Open Access Journals (Sweden)

    A. I. Gordienko

    2012-01-01

    Full Text Available Researches on influence of high-speed heating temperature, regimes of cooling and temperature of abatement on structure and mechanical properties of pipe steel 32G2 are carried out. Recommendations on the regimes of high-speed thermal processing of steel 32G2 which can be used at manufacturing of seamless pipes are given.

  8. Influence of steel composition and plastic deformation on the surface properties induced by low temperature thermochemical processing

    DEFF Research Database (Denmark)

    Bottoli, Federico

    Low-temperature thermochemical surface hardening by nitriding, carburizing and nitrocarburizing is used to improve the performance of stainless steels with respect to wear, fatigue and corrosion resistance.The dissolution of nitrogen and/or carbon atoms in the materials surface leads to the forma......Low-temperature thermochemical surface hardening by nitriding, carburizing and nitrocarburizing is used to improve the performance of stainless steels with respect to wear, fatigue and corrosion resistance.The dissolution of nitrogen and/or carbon atoms in the materials surface leads...... products. The activities carried out encompass the study and the characterization of the following aspects: ‐ Influence of plastic deformation prior to the low-temperature thermochemical process ‐ Influence of initial phase composition on the properties and morphology of thenitrided/nitrocarburized surface...... layer ‐ Influence of interstitial alloying on the mechanical properties of stainless steels ‐ Study of the corrosion performance of expanded austenite layer. ‐ Study of compressive residual stresses in expanded austenite and the influence of the material condition prior to nitriding/nitrocarburizing...

  9. Influence of dissolved hydrogen on the fatigue crack growth behaviour of AISI 4140 steel

    Science.gov (United States)

    Ramasagara Nagarajan, Varun

    Many metallic structural components come into contact with hydrogen during manufacturing processes or forming operations such as hot stamping of auto body frames and while in service. This interaction of metallic parts with hydrogen can occur due to various reasons such as water molecule dissociation during plating operations, interaction with atmospheric hydrogen due to the moisture present in air during stamping operations or due to prevailing conditions in service (e.g.: acidic or marine environments). Hydrogen, being much smaller in size compared to other metallic elements such as Iron in steels, can enter the material and become dissolved in the matrix. It can lodge itself in interstitials locations of the metal atoms, at vacancies or dislocations in the metallic matrix or at grain boundaries or inclusions (impurities) in the alloy. This dissolved hydrogen can affect the functional life of these structural components leading to catastrophic failures in mission critical applications resulting in loss of lives and structural component. Therefore, it is very important to understand the influence of the dissolved hydrogen on the failure of these structural materials due to cyclic loading (fatigue). For the next generation of hydrogen based fuel cell vehicles and energy systems, it is very crucial to develop structural materials for hydrogen storage and containment which are highly resistant to hydrogen embrittlement. These materials should also be able to provide good long term life in cyclic loading, without undergoing degradation, even when exposed to hydrogen rich environments for extended periods of time. The primary focus of this investigation was to examine the influence of dissolved hydrogen on the fatigue crack growth behaviour of a commercially available high strength medium carbon low alloy (AISI 4140) steel. The secondary objective was to examine the influence of microstructure on the fatigue crack growth behaviour of this material and to determine the

  10. Influence of gas pressure and substrate temperature on PIII nitrocarburizing process of AISI 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Abd El-Rahman, A.M. [Physics Department, Faculty of Science, South Valley University, Sohag Branch, Sohag (Egypt) and Institute of Ion Beam Physics and Material Research, FWII, Forschungszentrum Rossendorf, 01314 Dresden (Germany)]. E-mail: ahmedphys96@hotmail.com; El-Hossary, F.M. [Physics Department, Faculty of Science, South Valley University, Sohag Branch, Sohag (Egypt); Negm, N.Z. [Physics Department, Faculty of Science, South Valley University, Sohag Branch, Sohag (Egypt); Prokert, F. [Institute of Ion Beam Physics and Material Research, FWII, Forschungszentrum Rossendorf, 01314 Dresden (Germany); Richter, E. [Institute of Ion Beam Physics and Material Research, FWII, Forschungszentrum Rossendorf, 01314 Dresden (Germany); Moeller, W. [Institute of Ion Beam Physics and Material Research, FWII, Forschungszentrum Rossendorf, 01314 Dresden (Germany)

    2004-12-01

    Plasma immersion ion implantation (PIII) has been used to modify the surface properties of 304 austenitic stainless steel (AISI). The influence of working gas pressure, 0.2-1.0 Pa, and substrate temperature, 300-500 deg. C, on the microstructure, treating rate, nitrogen/carbon concentration depth profile, and surface microhardness was investigated. A gas composition of 25% C{sub 2}H{sub 2}, 75% N{sub 2}, r.f. plasma power input of 350 W, and a negatively biased potential of 30 kV were fixed during the experiment. The experimental results show that the substrate temperature and the diffusion process of nitrogen and carbon depend on the gas pressure inside the plasma chamber. The thickness of the modified layer has been found to be more than 30 {mu}m for samples were treated in the plasma for 60 min. The results show also that the values of diffusion coefficient and surface microhardness of the treated samples are high to be 3.4 x 10{sup -1} {mu}m{sup 2}/s and 1880 kg/mm{sup 2}, respectively.

  11. Influence of gas pressure and substrate temperature on PIII nitrocarburizing process of AISI 304 stainless steel

    Science.gov (United States)

    Abd El-Rahman, A. M.; El-Hossary, F. M.; Negm, N. Z.; Prokert, F.; Richter, E.; Möller, W.

    2004-12-01

    Plasma immersion ion implantation (PIII) has been used to modify the surface properties of 304 austenitic stainless steel (AISI). The influence of working gas pressure, 0.2-1.0 Pa, and substrate temperature, 300-500 °C, on the microstructure, treating rate, nitrogen/carbon concentration depth profile, and surface microhardness was investigated. A gas composition of 25% C2H2, 75% N2, r.f. plasma power input of 350 W, and a negatively biased potential of 30 kV were fixed during the experiment. The experimental results show that the substrate temperature and the diffusion process of nitrogen and carbon depend on the gas pressure inside the plasma chamber. The thickness of the modified layer has been found to be more than 30 μm for samples were treated in the plasma for 60 min. The results show also that the values of diffusion coefficient and surface microhardness of the treated samples are high to be 3.4 × 10-1 μm2/s and 1880 kg/mm2, respectively.

  12. Influence of deformation on structural-phase state of weld material in St3 steel

    International Nuclear Information System (INIS)

    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

  13. Influence of Light Rare Earth on Toughness of Welded Seam of LAHS Steel

    Institute of Scientific and Technical Information of China (English)

    李慕勤; 马臣; 刘冬梅

    2003-01-01

    The influence mechanism of light rare earth elements, which are transited to the welding seam of low-alloy high strength (LAHS) steel through the covering of the electrode, on the toughness of the welding seam was studied. The experimental results show that proper amount of rare earth elements can desulfurate, dehydrogenate, reduce inclusions and purify the structure of the welding seam. Rare earth element additions have the effect on welding seam and, at the same time, the transformation of side-batten ferrite is resisted while the pin-ferrite structure is promoted. The improvement of the toughness of the welding seam is due to the purifying action of rare earth elements as well as their refining effect on the structure. However, the toughness of the welding seam can decrease when the amount of light rare earth elements are added excessively because the crystal grains become coarser, porosities appear and the inclusions increase as well. The experimental results show that the suitable amount of light rare earth element additions is about 2%.

  14. Influence of cold rolling and annealing on mechanical properties of steel QStE 420

    Directory of Open Access Journals (Sweden)

    I. Schindler

    2006-08-01

    Full Text Available Purpose: was to investigate impact of cold reduction size and annealing on mechanical properties of HSLAsteel.Design/methodology/approach: Testing of strip steel QStE 420 was based on a combination of cold rolling,recrystallization annealing, mechanical testing and metallographic analyses.Findings: It was confirmed that by a suitable combination of size of previous cold deformation and parametersof the following annealing it is possible to influence considerably a complex of mechanical properties ofparticular strips. Strength properties were more or less decreasing with the rising annealing temperature, whereasplastic properties were increasing.Research limitations/implications: The experiment should be supplemented by additional modes of soft- andrecrystallization annealing.Practical implications: The results may be utilized for optimization of terms of heat treatment in a cold rollingmill, exactly in accordance with specific requirements for a relation between plastic and strength properties ofthe investigated material.Originality/value: Research possibilities of VSB-TUO in the sphere of cold rolling were introduced for thefirst time.

  15. The influence of electropolishing on the corrosion resistance of 316L stainless steel.

    Science.gov (United States)

    Sutow, E J

    1980-09-01

    A study was conducted which examined the influence of electropolishing on the corrosion resistance of a cold rolled 316L stainless steel. Test specimens were surface prepared to a final mechanical finish of wetted 600 grit SiC paper, prior to electropolishing. An o-H3PO4/Glycerol/H2O electropolishing solution was employed for times of 15, 20, and 25 min. Control specimens were surface prepared only to the final mechanical finish. Anodic polarization tests were performed in a deaerated Ringer's solution (37 degrees C) which was acidified to pH 1, with HCl. The electropolished specimens demonstrated increased corrosion resistance, when compared to the control specimens. This was evidenced for the former by more anodic corrosion and breakdown potentials, and the absence of a dissolution peak which was observed for the control specimens at the initial polarization potentials. Surface hardness measurements indicated that this increase in corrosion resistance was produced, in part, by the removal of the cold worked surface layer produced by the mechanical finish. In terms of increasing corrosion resistance, no optimum electropolishing time was found within the 15-25 min treatment period. PMID:7349665

  16. 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.

  17. Microbiologically Influenced Corrosion of 2707 Hyper-Duplex Stainless Steel by Marine Pseudomonas aeruginosa Biofilm

    Science.gov (United States)

    Li, Huabing; Zhou, Enze; Zhang, Dawei; Xu, Dake; Xia, Jin; Yang, Chunguang; Feng, Hao; Jiang, Zhouhua; Li, Xiaogang; Gu, Tingyue; Yang, Ke

    2016-02-01

    Microbiologically Influenced Corrosion (MIC) is a serious problem in many industries because it causes huge economic losses. Due to its excellent resistance to chemical corrosion, 2707 hyper duplex stainless steel (2707 HDSS) has been used in the marine environment. However, its resistance to MIC was not experimentally proven. In this study, the MIC behavior of 2707 HDSS caused by the marine aerobe Pseudomonas aeruginosa was investigated. Electrochemical analyses demonstrated a positive shift in the corrosion potential and an increase in the corrosion current density in the presence of the P. aeruginosa biofilm in the 2216E medium. X-ray photoelectron spectroscopy (XPS) analysis results showed a decrease in Cr content on the coupon surface beneath the biofilm. The pit imaging analysis showed that the P. aeruginosa biofilm caused a largest pit depth of 0.69 μm in 14 days of incubation. Although this was quite small, it indicated that 2707 HDSS was not completely immune to MIC by the P. aeruginosa biofilm.

  18. Influence of surface roughness of stainless steel on microbial adhesion and corrosion resistance

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel; Bagge-Ravn, Dorthe; Kold, John;

    2003-01-01

    Abstract The aim of this study was to evaluate if hygienic characteristics of stainless steel used in the food industry could be improved by smoothing surface roughness from an Ra of 0.9 to 0.01 ƒÝm. The adherence of Pseudomonas sp., Listeria monocytogenes and Candida lipolytica to stainless steel...

  19. On the Influence of Cross-Rolling on Shear Band Formation and Texture Evolution in Low Carbon Steel Sheets

    OpenAIRE

    Huh, M. Y.; Engler, O.; Raabe, D.

    1995-01-01

    In order to understand the influence of the crystallographic texture and the dislocation structure on the deformation mechanism in low carbon steels, the development of the texture and the microstructure in cross-rolled specimens was investigated by employing X-ray texture measurements and TEM observations. The cross-rolled specimens were obtained by rotating the rolling direction by various angles up to 90° after 30% initial straight-rolling of the hot rolled band. Whereas only few shear ban...

  20. Influence of Carbide Precipitation and Dissolution on the Microstructure of Ultra-Fine-Grained Intercritically Annealed Medium Manganese Steel

    Science.gov (United States)

    Lee, Sangwon; De Cooman, Bruno C.

    2016-07-01

    The influence of cementite precipitation and dissolution on the formation of the carbide-free, ultra-fine-grained, ferrite + austenite microstructure of medium manganese steel was analyzed. During heating to the intercritical temperature, cementite nucleates at low-angle lath martensite boundaries, austenite subsequently nucleates at ferrite/cementite boundaries, and the cementite is gradually replaced by the growing austenite grains. The intercritical austenite carbon is therefore due to cementite dissolution, rather than carbon partitioning between ferrite and austenite.

  1. Studing the Influence of Six Main Industrial Losses on Overall Equipment Effectiveness in Cold Rolling Unit of Mobarakeh Steel Complex

    OpenAIRE

    seyed Akbar Nilipour Tabatabaei; Abdolrahim Rostamzadeh; Mohammad Mehdi Rostamzadeh

    2011-01-01

    Overall Equipment Effectiveness (OEE) is a key indicator and a basis for evaluating the effectiveness of equipments as well as assessing the effectiveness of the Total Productive Maintenance (TPM) system. This indicator together with overall equipment performance can be used in production lines such as steel production. The aim of this article is to study the influence of six main industrial losses on the OEE indicator . For this purpose, the OEE has been calculated in the cold rolling produc...

  2. Beneficial influence of an intercritically rolled recovered ferritic matrix on the mechanical properties of TRIP-assisted multiphase steels

    OpenAIRE

    Godet, S.; Jacques, Pascal

    2015-01-01

    The present study deals with the microstucture and mechanical properties of intercritically rolled TRIP-assisted multiphase steels. It is shown that the occurrence of the TRIP effect in a recovered ferritic matrix brings about an improved strength-ductility balance with respect to a fully recrystallised ferrite matrix. On the other hand, the intercritical deformation does not influence the austenite transformation rate during straining at room temperature. The improvement of the mechanical pr...

  3. Complex influence of carbon, niobium and vanadium on the mechanical properties of the structural steel S355N

    OpenAIRE

    Рябікіна, Марина Анатоліівна; Ставровська, В. Є.

    2015-01-01

    The role of microalloying additions of V, Nb, Ti manifested mainly as a result of their influence on the formation of substitution solid solution; dispersion, shape and distribution of the carbides (carbonitrides); the structure of boundaries and the fine structure of the grains; reducing the negative impact of harmful impurities. It is important to precise knowledge of the required number of microalloying elements in the steel. The objective of the present article is to review the role of Nb...

  4. The influence of flection deformation on micro-mechanical properties of multilayer titanium-steel composite

    International Nuclear Information System (INIS)

    A systematic analysis of microhardness variation is performed to study structural-mechanical heterogeneity in 14-layer titanium-steel (titanium VT1-0 + steel 08kp) composite specimens, produced by explosion welding with subsequent rolling at 700 deg C. The specimens studied are subjected to bending under a symmetrical three-point loading. Substantial changes in microhardness are revealed depending on the value and the sign of deformation. Tensile deformation of 15-17 % gives rise to partial softening of both titanium and steel layers. In a range of 1-2 % of compressive load deformation the steel layers are softened. At deformation above 4 % the steel is prone to hardening. In the titanium layers the microhardness monotonically increases with deformation

  5. Influence of austenitizing temperature on apparent morphologies of as-quenched microstructures of steels

    Institute of Scientific and Technical Information of China (English)

    LIU Yue-jun; LI Yi-min; HUANG Bai-yun

    2006-01-01

    The effects of austenitizing temperature on the morphologies and substructures of as-quenched microstructure were investigated by using 13 medium and high carbon steels. The formation reasons of various morphologies of martensite quenched at different austenitizing temperatures were also studied. The results show that the packet martensite in medium and high carbon steels quenched at higher austenitizing temperature is entirely different from that in as-quenched low carbon steels, which is still plate martensite, and not lath martensite. All the change laws of as-quenched microstructures in medium and high carbon steels are identical with an increase in austenitizing temperature, and the austenitizing temperature can merely change the combined morphology of martensitic platelets,but cannot alter the type of product of martensitic transformation in commercial steels.

  6. Generation of a high temperature material data base and its application to creep tests with French or German RPV-steel. Technical report

    International Nuclear Information System (INIS)

    Considering the hypothetical core melt down scenario for a light water reactor (LWR) a possible failure mode of the reactor pressure vessel (RPV) and its failure time has to be investigated for a determination of the loadings on the containment. Numerous experiments have been performed accompanied with material properties evaluation, theoretical, and numerical work /REM 1993/, /THF 1997/, /CHU 1999/. For pre- and post-test calculations of Lower Head Failure experiments like OLHF or FOREVER it is necessary to model creep and plasticity processes. Therefore a Finite Element Model is developed at the FZR using a numerical approach which avoids the use of a single creep law employing constants derived from the data for a limited stress and temperature range. Instead of this a numerical creep data base (CDB) is developed where the creep strain rate is evaluated in dependence on the current total strain, temperature and equivalent stress. A main task for this approach is the generation and validation of the CDB. Additionally the implementation of all relevant temperature dependent material properties has been performed. For an evaluation of the failure times a damage model according to an approach of Lemaitre is applied. The validation of the numerical model is performed by the simulation of and comparison with experiments. This is done in 3 levels: starting with the simulation of single uniaxial creep tests, which is considered as a 1D-problem. In the next level so called ''tube-failure-experiments'' are modeled: the RUPTHER-14 and the ''MPA-Meppen''-experiment. These experiments are considered as 2D-problems. Finally the numerical model is applied to scaled 3D-experiments, where the lower head of a PWR is represented in its hemispherical shape, like in the FOREVER-experiments. This report deals with the 1D- and 2D-simulations. An interesting question to be solved in this frame is the comparability of the French 16MND5 and the German 20MnMoNi55 RPV-steels, which are

  7. Simulation study on factors influencing the entrainment behavior of liquid steel as bubbles pass through the steel/slag interface

    Institute of Scientific and Technical Information of China (English)

    Xiang Li; Yan-ping Bao; Min Wang; Lu Lin

    2016-01-01

    In this study, a water/silicone oil interface was used to simulate the steel/slag interface in a converter. A high-speed camera was used to record the entrainment process of droplets when air bubbles were passed through the water/silicone oil interface. Motion parameters of the bubbles and droplets were obtained using particle kinematic analysis software, and the entrainment rate of the droplets was calculated. It was found that the entrainment rate decreased from 29.5% to 0 when the viscosity of the silicone oil was increased from 60 mPa·s to 820 mPa·s in the case of bubbles with a 5 mm equivalent diameter passing through the water/silicone oil interface. The results indicate that in-creasing the viscosity of the silicone oil is conducive to reducing the entrainment rate. The entrainment rate increased from 0 to 136.3% in the case of silicone oil with a viscosity of 60 mPa·s when the equivalent diameter of the bubbles was increased from 3 mm to 7 mm. We there-fore conclude that small bubbles are also conductive to reducing the entrainment rate. The force analysis results for the water column indicate that the entrainment rate of droplets is affected by the velocity of the bubble passing through the water/silicone oil interface and that the en-trainment rate decreases with the bubble velocity.

  8. Influence of oxide scales on the corrosion behaviors of B510L hot-rolled steel strips

    Science.gov (United States)

    Man, Cheng; Dong, Chao-fang; Xue, Hui-bin; Xiao, Kui; Li, Xiao-gang; Qi, Hui-bin

    2016-07-01

    The influence of oxide scales on the corrosion behaviors of B510L hot-rolled steel strips was investigated in this study. Focused ion beams and scanning electron microscopy were used to observe the morphologies of oxide scales on the surface and cross sections of the hot-rolled steel. Raman spectroscopy and X-ray diffraction were used for the phase analysis of the oxide scales and corrosion products. The corrosion potential and impedance were measured by anodic polarization and electrochemical impedance spectroscopy. According to the results, oxide scales on the hot-rolled strips mainly comprise iron and iron oxides. The correlation between mass gain and test time follows a power exponential rule in the damp-heat test. The corrosion products are found to be mainly composed of γ-FeOOH, Fe3O4, α-FeOOH, and γ-Fe2O3. The contents of the corrosion products are different on the surfaces of the steels with and without oxide scales. The steel with oxide scales is found to show a higher corrosion resistance and lower corrosion rate.

  9. The influence of heating rate on reheat-cracking in a commercial 2 1/4Cr1Mo steel

    International Nuclear Information System (INIS)

    The effects of elevated heating rate on stress-relief cracking in a commercial 2 1/4 Cr1Mo steel have been investigated. A SEN bend-specimen stress-relaxation test was used to assess reheat cracking susceptibility and fracture mechanisms for an initial post-weld heating rate of 1000 Kh-1. Two factors controlling the influence of heating rate on the final severity of cracking were identified, i.e. the rate of stress-relaxation with respect to temperature, and the time available for crack-growth. The factors were found to counteract each other, but in the case of commercial 2 1/4 Cr1Mo steel, the crack-growth factor outweighed the relaxation factor, resulting in a reduction in the propensity to stress-relief cracking at the elevated heating rate. However, by reference to the results of a separate investigation concerning A508/2 MnMoNiCr steel it was demonstrated that the balance between these two factors may be reversed in other alloy systems, with the consequence that reheat cracking is exacerbated by increasing the initial heating rate. A computer model was addressed to the stress-relaxation test conditions using data from the commercial 2 1/4 Cr1Mo steel. The model predictions exhibited reasonable agreement with experimental test results for both 100 Kh-1 and 1000 Kh-1 heating rates. (author)

  10. Research of influence of gas nitriding duration on formation of diffusion layer of steel 20Kh2N4A

    Directory of Open Access Journals (Sweden)

    Kateryna O. Kostyk

    2015-06-01

    Full Text Available The research of the gas nitriding process, which allows to obtain a high surface quality of steel parts and has a wide application in mass production, is relevant. Aim of the research is to study the influence of gas nitriding modes on the structure and properties of alloy steel. The research material in this work is steel 20Kh2N4A. Nitriding of the samples is carried out in a shaft furnace at the temperature of 510…530 °C during 35, 40, 46 and 48 h. It is found that the alloy steel 20Kh2N4A preliminary heat treatment before nitriding provides the hardness of products core to 279...321 HV due to the formation of perlite-sorta structure with carbides of alloying elements. The results show that increasing the duration of nitriding from 35 to 48 hours at 510…530 °С increases the depth of nitrided layer from 0,35 to 0,55 mm with surface hardness up to 648 MPa at the maximum depth of the layer. The results of this research can be used in industry and research works.

  11. Influence of Microstructure, Produced by Heat Treatment and Sever Plastic Deformation, on Tribological Properties of Low-carbon Steel

    Directory of Open Access Journals (Sweden)

    V. I. Semenov

    2011-06-01

    Full Text Available This paper presents the results of tribological investigations conducted on steel 20 with the carbon content of up to 0.2%. The steel was studied in the three conditions: initial (hot-rolled, after heat-treatment (quenching+tempering and after heat treatment with subsequent severe plastic deformation (SPD performed by equal channel angular pressing technique (ECAP. It was stated that after various treatments the material acquires various structural conditions and possesses various strength properties and has a considerable difference in oxygen content in the surface layer. This influences the tribological properties during the contact with tool steel. The lowest values of adhesive bond shear strength, friction coefficient and wear rate are demonstrated in the material after martempering with subsequent SPD by ECAP technique. The surface of the investigated material after SPD treatment by the ECAP technique possesses a highest bearing capacity and requires more time for wearing-in in friction assemblies. Oxygen content increase in the form of metal oxides on the surface of low-carbon steels is accompanied by a decrease of the adhesive component of friction coefficien.

  12. Microbially influenced corrosion of stainless steel welds; Stainless ko yosetsubu no biseibutsu yuki fushoku no kisoteki kento

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Y.; Tomoto, K.; Okayama, C.; Matsuda, F. [Osaka University, Osaka (Japan). Joining and Welding Research Institute; Nishimura, M. [Mitsubishi Kakoki Kaisha Ltd., Tokyo (Japan); Sakane, T. [Institute for Fermentation, Osaka (Japan); Kaneko, Y. [Osaka University, Osaka (Japan). Faculty of Engineering

    1997-06-20

    This paper describes sensitivities of microbiologically influenced corrosion (MIC) for various stainless steels. The failure in the weld joint of SUS steel pipes occurred in about 60 days from the start-up of the sewage treatment plant. Any welding defects were not found, and the corrosion rate of welds was estimated to be 18 mm per year which was too fast. The corrosion was reproduced using the residual liquid from effluent treatment plant in laboratory. Corrosion pits and bacteria adhering around these were observed at the same time. For the experiments using boiled and sterilized waste water, corrosion did not occur. As a result, MIC was confirmed. Seven kinds of bacteria were separated and identified from the waste water. Among individual bacteria separated and incubated, Methylobacterium sp. and Arthrobacter sp. showed the most strong corrosion properties. It was estimated that these bacteria produced organic acid and its concentration became high locally at the site adhered by bacteria to generate the corrosion. The MIC was observed for several kinds of stainless steels used. There was not a significant difference in anti-corrosion due to the kind of steel. 19 refs., 10 figs., 4 tabs.

  13. Influence of flexural fatigue on chloride threshold value for the corrosion of steels in Ca(OH){sub 2} solutions

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Linhua, E-mail: hhulhjiang@gmail.com [College of Mechanics and Materials, Hohai University, 1 Xikang Rd., Nanjing, 210098 (China); Hydraulic Engineering Research Center for New Materials and Protection, Jiangsu Province, 1 Xikang Rd., Nanjing, 210098 (China); Liu, Hao; Wang, Yongliang; Zhang, Yan; Song, Zijian; Xu, Jinxia; Jin, Ming; Jiang, Peng; Xu, Yi; Gao, Hailang [College of Mechanics and Materials, Hohai University, 1 Xikang Rd., Nanjing, 210098 (China)

    2015-08-15

    The flexural fatigue was enforced on reinforced concrete beam with stress level of 0.6 and different fatigue life cycles. Steels removed from the beams were soaked in the saturated Ca(OH){sub 2} solution, which was used as a simulated concrete pore solution. The NaCl solution was chosen as the source of chloride ions. The Chloride Threshold Values (CTV) were detected by combining the open-circuit potentials (E{sub corr}) with the corrosion current densities (i{sub corr}), which were obtained by electrochemical impedance spectroscopy (EIS). The changes of microstructure caused by the flexural fatigue were observed by scanning electron microscopy (SEM). The results showed that as the fatigue cycle times increased, the CTV decreased under a certain stress level and range of fatigue life cycles. The grains became finer and cracks appeared on the surface of the steels. While the capacitive arcs under no flexural fatigue decreased gradually with the addition of chloride ions, the ones under flexural fatigue presented no regularity. Cracks at the surface were expanded because of sustaining flexural fatigue, which degenerated the later resistance to chloride ions of the steels. - Highlights: • The influence of flexural fatigue on chloride threshold value was examined. • The chloride threshold values vary with different fatigue life cycles. • The corrosion behavior depends on the surface integrity of the steels.

  14. Influence of flexural fatigue on chloride threshold value for the corrosion of steels in Ca(OH)2 solutions

    International Nuclear Information System (INIS)

    The flexural fatigue was enforced on reinforced concrete beam with stress level of 0.6 and different fatigue life cycles. Steels removed from the beams were soaked in the saturated Ca(OH)2 solution, which was used as a simulated concrete pore solution. The NaCl solution was chosen as the source of chloride ions. The Chloride Threshold Values (CTV) were detected by combining the open-circuit potentials (Ecorr) with the corrosion current densities (icorr), which were obtained by electrochemical impedance spectroscopy (EIS). The changes of microstructure caused by the flexural fatigue were observed by scanning electron microscopy (SEM). The results showed that as the fatigue cycle times increased, the CTV decreased under a certain stress level and range of fatigue life cycles. The grains became finer and cracks appeared on the surface of the steels. While the capacitive arcs under no flexural fatigue decreased gradually with the addition of chloride ions, the ones under flexural fatigue presented no regularity. Cracks at the surface were expanded because of sustaining flexural fatigue, which degenerated the later resistance to chloride ions of the steels. - Highlights: • The influence of flexural fatigue on chloride threshold value was examined. • The chloride threshold values vary with different fatigue life cycles. • The corrosion behavior depends on the surface integrity of the steels

  15. Influence of thermal treatment on structure and corrosion properties of high manganese triplex steels

    OpenAIRE

    S. Lasek; Mazancová, E.

    2013-01-01

    In this paper corrosion properties of X70MnAl28-9 TRIPLEX steel were tested after hot rolling and subsequent aging at 500 °C for 6, 30 and 60 min. and at 600 °C for the same times. For comparison related steels(X100MnAl28-12, X70Mn22, C20) were also used. The microstructure wascharacterized by light microscopy, SEM, energy disperse Xray microanalysis. The corrosion behaviour of steels wasexamined by light and scanning electron microscopy, electrochemical techniques (potenciodynamic polarizati...

  16. Return on shares of steel companies under the influence of mergers and acquisitions

    Directory of Open Access Journals (Sweden)

    J. Zuzik

    2015-01-01

    Full Text Available The present article intends to asses returns on shares of the steel companies that were formed based on either merger or acquisition. The analysis included 14 operations in the steel industry. Attention was paid to returns of the companies performing acquisitions, as well as to the returns on shares that presented the acquisition target. The analysis was performed based on the “event study” method, and the analysed event was the announcement or notification of realization of an acquisition. Shares of the target steel companies as well as acquirers are attaining higher returns, but the change was not statistical significant.

  17. Influence of form method on structure and properties of high speed steels

    International Nuclear Information System (INIS)

    In the paper it has been demonstrated that experimental steels of the HS 6-5-2 and HS 12-1-5-5 type made by the polymer-powder slurry forming (PIM) characterized by a lower sintering temperature, in relation to the same steel grades manufactured by compaction and sintering (PM). It has been found out that higher density, more homogeneous structure with fine precipitations of carbide phases are obtained during sintering of steels formed out of the slurry in the atmosphere of inert gases. (author)

  18. THE ELECTROCHEMICAL BEHAVIOR OF OCEANIC MICROBIOLOGICAL INFLUENCED CORROSION ON CARBON STEEL

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The corrosion behavior of carbon steel in the medium of marine microorganisms was investigated by electrochemical impedance spectra, polarization curves, and so on. Experimental results showed that the corrosion potential of carbon steel moved in a negative direction in the unpurified marine microorganism solution, and the polarization style of the cathodic process did not change. The electrochemical impedance spectra showed that the impedance value of the electrode decreased in the medium with bacteria, which indicated that the existence of microorganism could accelerate the corrosion progress of carbon steel.

  19. Influence of Molybdenum Addition on Mechanical Properties of Low Carbon HSLA-100 Steel

    Directory of Open Access Journals (Sweden)

    Bogucki R.

    2014-10-01

    Full Text Available The results of mechanical properties and microstructure observation of low carbon copper bearing steel with high addition of molybdenum are presented in this paper. This steels were characterized by contents of molybdenum in the range from 1% to 3% wt. After the thermo -mechanical processing the steels were subsequently quenched and tempered at different temperatures (500-800 °C for 1h. The changes of mechanical properties as function of tempering temperature were typical for the steel with the copper addition. The sudden drop of impact resistance after tempering from 575 °C to 600 °C was caused probably by precipitates of Laves phase of type Fe2Mo.

  20. Influence of thermal treatment on the caustic SCC of super austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Y.R.; Park, Y.B.; Chung, T.J.; Kim, Y.S. [School of Advanced Materials Engineering, Andong National Univ. (Korea); Chang, H.Y. [Korea Power Engineering Co. (Korea); Park, Y.S. [Dept. of Metallurgical Engineering, Yonsei Univ. (Korea)

    2005-07-01

    In general, thermal treatment at 500 C {proportional_to} 900 C ranges depending upon alloy composition of stainless steels can sensitize the steels and promote the intergranular cracking, and their intergranular corrosion resistance is decreased. These behaviors seem to be related to the change of microstructures. So, heat treatment at that temperature range should be avoided in fabrication, especially welding of stainless steels. In this work, it is focused on the effect of thermal treatment on caustic stress corrosion cracking of super austenitic stainless steel - S32050 The low temperature thermal treatment increased greatly the resistance to caustic SCC than those of annealed specimen. This enhancement might be closely related to the reduction of residual stress and slightly large grain, but its resistance was not affected by the anodic polarization behavior. (orig.)

  1. Influence of calcium content on solid ratio of inclusions in Ca-treated liquid steel

    Institute of Scientific and Technical Information of China (English)

    Fangming Yuan; Xinhua Wang; Xuefu Yang

    2006-01-01

    It has been found that Ca-treated liquid steel can be cast at a lower superheat. To ascertain the reason for the improved castability of Ca-treated liquid steel and to find the optimal range of calcium content, the behavior of calcium in liquid steel was studied in terms of the relationship between the calcium content and solid ratio of inclusions. The relationship between the calcium content and solid ratio of inclusions was obtained by means of the classification of nonmetallic inclusions in solid and liquid steels at casting temperature according to the A12O3-CaO-SiO2 phase diagram. The optimum calcium content should be 17-23 ppm.

  2. Influence of Silica Fume on Corrosion Behaviour of Reinforced Steel in Different Media

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Electrochemical and corrosion behaviour of reinforced steel embedded in cement pastes incorporating differentamounts of silica fume as a partial replacement of cement has been studied in chloride and sulphate solutionsby using different electrochemical techniques. The results indicate that, while steel passivity degree is Iow in thecontrol samples upon soaking in the corrosive media, it has been high in samples incorporating silica fume andincreased with increasing silica fume content. The improvement effect of silica fume may be attributed to the poresolution structure of the cement paste, which limits the mobility of aggressive ions near the surface of the steel. Themechanism of steel corrosion due to chloride and sulphate attack and passivation effect of silica fume are discussed.

  3. THE INFLUENCE OF CARBON STEEL STRUCTURAL COMPONENTS DISPERSION ON FRACTURE RESISTANCE

    OpenAIRE

    I. O. Vakulenko; M. A. Hryshchenko; O. M. Perkov

    2007-01-01

    The observed questions of estimate stress intensity coefficient, strength of fatique and toughness behavior is considered to be result of a directional variation in the grain size of austenite and size of ferrite pearlite in carbon steel.

  4. Influence of ph on corrosion control of carbon steel by peroxide injection in sour water

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, Martins Magda; Baptista, Walmar; Joia, Carlos Jose Bandeira de Mello [PROTEMP - PETROBRAS/CENPES, Cidade Universitaria, Quadra 7, Rio de Janeiro, CEP 21949-900 (Brazil); Ponciano, Gomes Jose Antonio da Cunha [Departamento de Engenharia Metalurgica e de Materiais-COPPE/UFRJ, Cidade Universitaria, Rio de Janeiro (Brazil)

    2004-07-01

    Sour hydrogen damage is considered the most important corrosive process in the light-ends recovery section of Fluid Catalytic Cracking Units (FCCU). Corrosion in this condition is due to heavy gas oil that originates great amount of contaminants, such as H{sub 2}S, NH{sub 3} and HCN. Hydrogen absorption is promoted by the presence of free cyanides in the environment. The attenuation of this process requires the use of some inhibitors, such as oxygen, hydrogen peroxide (H{sub 2}O{sub 2}) or commercial polysulfides. The effect of these compounds is to neutralize free cyanides (CN{sup -}) into thio-sulfides (SCN{sup -}). When peroxide injection is selected, cyanide concentration in sour water has been used as key parameter to start the peroxide introduction. However, the importance of pH in this system has been pointed out by many authors. The aim of this work is to investigate the influence of pH when peroxide injection is carried out in less alkaline conditions of sour water. Electrochemical techniques - like anodic polarization and hydrogen permeation tests - and weight loss measurements were used to evaluate the effectiveness of corrosion control of carbon steel. It was concluded that at pH 7.5 peroxide injection can drive to an increment of the corrosion rate. Besides that, it was concluded that hydrogen permeation into the metal is promoted. Both detrimental effects were due to elemental sulfur generation in this pH range. The adoption of pH as a key parameter for peroxide injection is then suggested. (authors)

  5. Heat affected zone microstructures and their influence on toughness in two microalloyed HSLA steels

    International Nuclear Information System (INIS)

    Microstructures and Charpy impact properties have been examined in two microalloyed steels following heat treatments to simulate weld heat affected zone (HAZ) structures over a range of heat input conditions, characterised by the cooling time from 800 to 500 °C (Δt8/5). The base materials were low carbon structural steel plates microalloyed with vanadium and nitrogen (V–N) and niobium (Nb), respectively. The toughnesses of the HAZs displayed remarkably different behaviours as shown by their impact transition temperatures. For the V–N steel, the toughness improved with increasingly rapid cooling (low heat input conditions) whereas the Nb steel showed an opposite trend. Some of this behaviour could be explained by the presence of coarse ferrite grains in the slowly cooled V–N steel. However, other conditions where all the structures were bainitic and rather similar in optical micrographs gave widely different toughness values. The recently developed method of five dimensional boundary analysis based on electron backscattering diffraction has been applied to these cases for the first time. This showed that the lath boundaries in the bainite were predominantly on {1 1 0} planes of the ferrite and that the average spacing of these boundaries varied depending on steel composition and cooling rate. Since {1 1 0} is also the slip plane in ferrite, it is considered that close spacing between the lath boundaries inhibits general plasticity at stress concentrations and favours initiation of fracture. The differences between the two steels are believed to be due to their transformation behaviours on cooling where precipitation of vanadium nitride in austenite accelerates ferrite formation and raises the temperature of the phase transformation in V–N steels.

  6. Influence of Material Compressibility on Displacement Solution for Structural Steel Plate Applications

    OpenAIRE

    Nelli Aleksandrova

    2014-01-01

    Displacement field calculations are necessary for many structural steel engineering problems such as cold expansion of holes, embedment of bolts and rivets, and installation and maintenance of external devices. To this end, rigorous closed form analytical displacement solution is obtained for structural steel open-hole plates with in-plane loading. The material of the model is considered to be elastic perfectly plastic obeying the von Mises yield criterion with its associated flow rule. On th...

  7. Influence of Heat Treatment on the Corrosion of Microalloyed Steel in Sodium Chloride Solution

    OpenAIRE

    Asiful Hossain Seikh

    2013-01-01

    Microalloyed Steels find wide application in car bodies and other engineering parts because of its high strength as well as high ductility. Very fine grained microstructure is the reason behind the combination of strength and ductility. It has been reported that repeated quenching leads to further refining of microstructure. In the present investigation, corrosion resistance property of E34 microalloy steel has been studied in 3.5% NaCl solution in different microstructural conditions such as...

  8. Parameters Influencing the Corrosion Protection Service Life of Epoxy Coated Reinforcing Steel in Virginia Bridge Decks

    OpenAIRE

    Wheeler, Megan Caroline

    2003-01-01

    This study is an evaluation of epoxy coated reinforcing steel (ECR) and its ability to effectively provide corrosion protection in reinforced concrete highway bridge decks. An analysis was conducted on 10 bridge decks built in the state of Virginia between the years 1981 and 1995. A total of 141 cores containing either ECR or bare steel were evaluated. A chloride solution was applied to the surface on a weekly cycle (for a total duration of 3.06 years) and a nondestructive electrochemica...

  9. The influence of thiosulphate ions on the localized corrosion of stainless steel

    International Nuclear Information System (INIS)

    The thiosulphate ion (S2O32-) can be formed either by microbial activity or by air-oxidation of metal sulphides, e.g. in blast-furnace slag. Since blast-furnace slag may be added to concrete for nuclear waste containment, information on the corrosion effects of thiosulphate on stainless steels such as are likely to be used for waste canisters in contact with such concrete has been reviewed and areas requiring further study identified. In neutral solutions, thiosulphate is extremely corrosive towards stainless steels. Pitting corrosion has been reported for Type 304 steel in solutions containing less than 10-5 molar thiosulphate ions, provided that an appropriate amount of sulphate is present. Chloride ions are not necessary for pitting of this alloy. Two mitigating circumstances lead to the conclusion that Type 316L steel will probably not suffer from thiosulphate corrosion under disposal conditions. First, the concrete environment has a high pH (≥ 12.5), and this has been shown to inhibit pitting. Second, no pitting of Type 316L steel has so far been detected in solutions where sulphate (rather than chloride) is the predominant anion. Experimental confirmation of the good resistance of Type 316L steel has been achieved using a scratching test. (author)

  10. Influence of boron on strain hardening behaviour and ductility of low carbon hot rolled steel

    International Nuclear Information System (INIS)

    Highlights: → Unique feature of low strain hardening exponent (n) with high total elongation has been discussed in industrially produced low carbon boron containing steel. → n has been correlated with the micro structural changes occurring during deformation of steel. → This feature of low n and high % elongation has potential for higher cold reducibility. → The work is being reported for the first time on industrially produced low carbon boron containing steel. - Abstract: The beneficial effect of boron on mechanical properties of low carbon Al-killed steel has been reported in recent past. However, the effect of boron on strain hardening exponent (n) and ductility has not been fully understood. This aspect has been discussed in present work. The results of mill trials with reference to n and ductility with boron added steel are compared to those for commercial grade. The lowering of 'n' with increased total elongation in boron bearing steel has been related to the microstructural evolution as a result of boron addition.

  11. The influence of deformation-induced residual stresses on the post-forming tensile stress/strain behavior of dual-phase steels

    Science.gov (United States)

    Hance, Brandon Michael

    It was hypothesized that, in dual-phase (DP) steels, strain partitioning between ferrite (alpha) and martensite (alpha') during deformation results in a distribution of post-deformation residual stresses that, in turn, affects the subsequent strength, work hardening behavior and formability when the strain path is changed. The post-forming deformation-induced residual stress state was expected to depend upon the microstructure, the amount of strain and the prestrain path. The primary objective of this research program was to understand the influence of deformation-induced residual stresses on the post-forming tensile stress/strain behavior of DP steels. Three commercially produced sheet steels were considered in this analysis: (1) a DP steel with approximately 15 vol. % martensite, (2) a conventional high-strength, low-alloy (HSLA) steel, and (3) a conventional, ultra-low-carbon interstitial-free (IF) steel. Samples of each steel were subjected to various prestrain levels in various plane-stress forming modes, including uniaxial tension, plane strain and balanced biaxial stretching. Neutron diffraction experiments confirmed the presence of large post-forming deformation-induced residual stresses in the ferrite phase of the DP steel. The deformation-alphainduced residual stress state varied systematically with the prestrain mode, where the principal residual stress components are proportional to the principal strain components of the prestrain mode, but opposite in sign. For the first time, and by direct experimental correlation, it was shown that deformation-induced residual stresses greatly affect the post-forming tensile stress/strain behavior of DP steels. As previously reported in the literature, the formability (residual tensile ductility) of the IF steel and the HSLA steel was adversely affected by strain path changes. The DP steel presents a formability advantage over the conventional IF and HSLA steels, and is expected to be particularly well suited for

  12. The Influence of Nano-Al2O3 Additive on the Adhesion between Epoxy Resin and Steel Substrate

    Institute of Scientific and Technical Information of China (English)

    ZHAILan-lan; LINGGuo-ping

    2004-01-01

    The influence of nano-A1203 additive on the adhesion between epoxy resin and steel substrate has been investigated. The results of tensile testing indicated that the adhesion strength was increased dramatically by addition of Al2O3 nanoparticles in epoxy resin compared with that of the unmodified resin. The highest adhesion strength was obtained with 1 wt% nano-Al2O3 added in epoxy adhesive, more than two times higher than that of the unmodified. Scanning electronic microscope (SEM) revealed that a boundary layer exists between epoxy and steel substrate, energy spectrum analysis indicates there is enrichment of the nano-Al2O3 particle. Those results confirmed that the nano-Al2O3 additive was closely related to the change of interface morphology and the improvement of adhesion strength. The reason for adhesion improvement was also be discussed.

  13. The Influence of Nano-Al2O3 Additive on the Adhesion between Epoxy Resin and Steel Substrate

    Institute of Scientific and Technical Information of China (English)

    ZHAI Lan-lan; LING Guo-ping

    2004-01-01

    The influence of nano-Al2O3 additive on the adhesion between epoxy resin and steel substrate has been investigated. The results of tensile testing indicated that the adhesion strength was increased dramatically by addition of Al2O3 nanoparticles in epoxy resin compared with that of the unmodified resin. The highest adhesion strength was obtained with 1 wt% nano-Al2O3 added in epoxy adhesive, more than two times higher than that of the unmodified. Scanning electronic microscope (SEM) revealed that a boundary layer exists between epoxy and steel substrate, energy spectrum analysis indicates there is enrichment of the nano-Al2O3 particle. Those results confirmed that the nano-Al2O3 additive was closely related to the change of interface morphology and the improvement of adhesion strength. The reason for adhesion improvement was also be discussed.

  14. Influence of cubic boron nitride grinding on the fatigue strengths of carbon steels and a nickel-base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Kawagoishi, N.; Chen, Q.; Kondo, E. [Kagoshima Univ. (Japan). Faculty of Engineering; Goto, M. [Oita Univ. (Japan). Faculty of Engineering; Nisitani, H. [Kyushu Sangyo Univ., Fukuoka (Japan). Faculty of Engineering

    1999-04-01

    The influence of cubic boron nitride (CBN) grinding on fatigue strength was investigated on an annealed carbon steel, a quenched and tempered carbon steel at room temperature, and a nickel-base superalloy, Inconel 718, at room temperature and 500 C. The results were discussed from several viewpoints, including surface roughness, residual stress, and work hardening or softening due to CBN grinding. The fatigue strength increased upon CBN grinding at room temperature, primarily because of the generation of compressive residual stress in the surface region. However, in the case of Inconel 718, this marked increase in the fatigue strength tended to disappear at the elevated temperature due to the release of compressive residual stress and the decrease of crack growth resistance at an elevated temperature.

  15. Study the influence of a new ball burnishing technique on the surface roughness of AISI 1018 low carbon steel

    Directory of Open Access Journals (Sweden)

    Abd Alkader Ibrahim

    2015-02-01

    Full Text Available Hard roller burnishing with a ball tool is a surface-finishing where a free-rotating tool rolls over the machined surface under high pressures and flattens the surface roughness peaks by cold work. In the present work, a new burnishing technique has been applied which enables both single and double ball burnishing process in site after turning without releasing the specimen. Sets of experiments are conducted to investigate the influence of burnishing force, feed, speed and number of tool passes on surface roughness of AISI 1018 Low Carbon Steel specimens. Burnishing results showed significant effectiveness of the new burnishing technique in the process. The results revealed that minimum surface roughness are obtained by applying the double ball burnishing process on AISI 1018 Low Carbon Steel specimens. Improvement in surface finish can be achieved in both single and double ball burnishing by increasing the number of burnishing tool passes. The results are presented in this paper.

  16. Influence of structural parameters on the tendency of VVER-1000 reactor pressure vessel steel to temper embrittlement

    Science.gov (United States)

    Gurovich, B.; Kuleshova, E.; Zabusov, O.; Fedotova, S.; Frolov, A.; Saltykov, M.; Maltsev, D.

    2013-04-01

    In this paper the influence of structural parameters on the tendency of steels to reversible temper embrittlement was studied for assessment of performance properties of reactor pressure vessel steels with extended service life. It is shown that the growth of prior austenite grain size leads to an increase of the critical embrittlement temperature in the initial state. An embrittlement heat treatment at the temperature of maximum manifestation of temper embrittlement (480 °C) shifts critical embrittlement temperature to higher values due to the increase of the phosphorus concentration on grain boundaries. There is a correlation between phosphorus concentration on boundaries of primary austenite grains and the share of brittle intergranular fracture (that, in turn, depends on impact test temperature) in the fracture surfaces of the tested Charpy specimens.

  17. Influences of silicon on the work hardening behavior and hot deformation behavior of Fe–25 wt%Mn–(Si, Al) TWIP steel

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dejun, E-mail: lidejun352@163.com [CNPC Tubular Goods Research Institute, Xi’an 710077 (China); The Key Lab for Petroleum Tubular Goods Engineering, CNPC, Xi’an 710077 (China); Feng, Yaorong; Song, Shengyin; Liu, Qiang; Bai, Qiang [CNPC Tubular Goods Research Institute, Xi’an 710077 (China); The Key Lab for Petroleum Tubular Goods Engineering, CNPC, Xi’an 710077 (China); Ren, Fengzhang [School of Material Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Shangguan, Fengshou [CNPC Tubular Goods Research Institute, Xi’an 710077 (China); The Key Lab for Petroleum Tubular Goods Engineering, CNPC, Xi’an 710077 (China)

    2015-01-05

    Highlights: • Influence of Si on work hardening behavior of Fe–25 wt%Mn TWIP steel was investigated. • Influence of Si on hot deformation behavior of Fe–25 wt%Mn TWIP steel was studied. • Si blocks dislocation glide and favors mechanical twinning in Fe–25 wt%Mn TWIP steel. • The addition of Si increases the hot deformation activation energy of Fe–25 wt%Mn TWIP steel. • The addition of Si retards the nucleation and growth of DRX grains of Fe–25 wt%Mn TWIP steel. - Abstract: The influence of silicon on mechanical properties and hot deformation behavior of austenitic Fe–25 wt%Mn TWIP steel was investigated by means of the comparison research between 25Mn3Al and 25Mn3Si3Al steel. The results show that the 25Mn3Si3Al steel has higher yield strength and higher hardness than that of 25Mn3Al steel because of the solution strengthening caused by Si atoms and possesses higher uniform deformation ability and tensile strength than that of 25Mn3Al steel due to the higher work hardening ability of 25Mn3Si3Al steel. 25Mn3Si3Al steel presents a clear four-stage curve of work hardening rate in course of cold compression. Quite the opposite, the 25Mn3Al steel presents a monotonic decline curve of work hardening rate. The difference of the work hardening behavior between 25Mn3Al and 25Mn3Si3Al steel can be attributed to the decline of stacking fault energy (SFE) caused by the addition of 3 wt% Si. The dislocation glide plays an important role in the plastic deformation of 25Mn3Al steel even though the mechanical twinning is still one of the main deformation mechanisms. The 3 wt% Si added into the 25Mn3Al steel blocks the dislocation glide and promotes the mechanical twinning, and then the dislocation glide characteristics cannot be observed in cold deformed microstructure of 25Mn3Si3Al steel. The hot compression tests reveal that the hot deformation resistance of the 25Mn3Si3Al steel is significantly higher than that of the 25Mn3Al steel due to the solid

  18. The influence of thermo - mechanical processing on deformability and structural changes of duplex steel

    Directory of Open Access Journals (Sweden)

    K. Radwański

    2007-01-01

    Full Text Available Purpose: In conventional hot deformation methods of duplex steels, low values of boundary strain are obtained,resulting from the disparate behaviour of ferrite and austenite. This paper analyses the capacity for enhancingdeformability of two-phase ferritic-austenitic steels of the “duplex” type via thermo mechanical processing.Design/methodology/approach: Steel specimens were subjected to cold deformation with a 70% rollingreduction. After a hot solution treatment beginning at 1350°C, the specimens were tensioned in the “Instron”strength-testing machine in temperatures ranging from 800 to 950°C at a rate of vr=15×10-3÷3×10-1mm/s ina 0.005Pa vacuum. Structural examination was carried out using light and electron microscopy. A quantitativeanalysis of structural changes was performed using the „MetIlo” image analysis programme.Findings: The process parameters at which the investigated steel shows the superplastic flow effect havebeen determined.Practical implications: The capacity for increased deformability through combined thermo - mechanicalprocesses, requiring a precise selection of the deformation parameters, has been indicated.Originality/value: The results obtained are vital for designing an effective thermo - mechanical processingtechnology for the investigated steel.

  19. Influence of sigma-phase formation on the localized corrosion behavior of a duplex stainless steel

    Science.gov (United States)

    Adhe, K. M.; Kain, V.; Madangopal, K.; Gadiyar, H. S.

    1996-08-01

    Because of their austenitic-ferritic microstructures, duplex stainless steels offer a good combination of mechanical and corrosion resistance properties. However, heat treatments can lower the mechanical strength of these stainless steels as well as render them susceptible to intergranular corrosion (IGC) and pitting corrosion. In this study, a low-carbon (0.02%) duplex stainless steel is subjected to various heat treatments at 450 to 950 °C for 30 min to 10 h. The heat-treated samples then undergo ASTM IGC and pitting corrosion tests, and the results are correlated with the microstructures obtained after each heat treatment. In the absence of Cr23C6 precipitation, σ-phase precipitates render this duplex stainless steel susceptible to IGC and pitting corrosion. Even submicroscopic σ-phase precipitates are deleterious for IGC resistance. Longer-duration heat treatments (at 750 to 850 °C) induce chromium diffusion to replenish the chromium-depleted regions around the σ-phase precipitates and improve IGC resistance; pitting resistance, however, is not fully restored. Various mechanisms of σ-phase formation are discussed to show that regions adjacent to σ-phase are depleted of chromium and molybdenum. The effect of chemical composition (pitting resistance equivalent) on the pitting resistance of various stainless steels is also noted.

  20. Influence of sigma-phase formation on the localized corrosion behavior of a duplex stainless steel

    International Nuclear Information System (INIS)

    Because of their austenitic-ferritic microstructures, duplex stainless steels offer a good combination of mechanical and corrosion resistance properties. However, heat treatments can lower the mechanical strength of these stainless steels as well as render them susceptible to intergranular corrosion (IGC) and pitting corrosion. In this study, a low-carbon (0.02%) duplex stainless steel is subjected to various heat treatments at 450 to 950 C for 30 min to 10 h. The heat-treated samples than undergo ASTM IGC and pitting corrosion tests, and the results are correlated with the microstructures obtained after each heat treatment. In the absence of Cr23C6 precipitation, σ-phase precipitates render this duplex stainless steel susceptible to IGC and pitting corrosion. Even submicroscopic σ-phase precipitates are deleterious for IGC resistance. Longer-duration heat treatments (at 750 to 850 C) induce chromium diffusion to replenish the chromium-depleted regions around the σ-phase precipitates and improve IGC resistance; pitting resistance, however, is not fully restored. Various mechanisms of σ-phase formation are discussed to show that regions adjacent to σ-phase are depleted of chromium and molybdenum. The effect of chemical composition (pitting resistance equivalent) on the pitting resistance of various stainless steels is also noted

  1. Influence of processing parameters on lattice parameters in laser deposited tool alloy steel

    International Nuclear Information System (INIS)

    Highlights: → Orientation relationships among phases in the DMD are given. → Martensite lattice parameters increased with laser specific energy. → Austenite lattice parameters decreased with laser specific energy. - Abstract: Laser aided direct metal deposition (DMD) has been used to form AISI 4340 steel coating on the AISI 4140 steel substrate. The microstructural property of the DMD coating was analyzed by means of scanning electron microscopy, transmission electron microscopy and X-ray diffractometry. Microhardness of the DMD was measured with a Vickers microhardness tester. Results indicate that DMD can be used to form dense AISI 4340 steel coatings on AISI 4140 steel substrate. The DMD coating is mainly composed of martensite and retained austenite. Consecutive thermal cycles have a remarkable effect on the microstructure of the plan view of the DMD coating and on the corresponding microhardness distribution. Orientation relationships among austenite, martensite and cementite in the DMD coating followed the ones in conventional heat treated steels. As the laser specific energy decreased, cooling rate increased, and martensite peaks broadened and shifted to a lower Bragg's angle. Also martensite lattice parameters increased and austenite lattice parameters decreased due to the above parameter change.

  2. Influence of processing parameters on lattice parameters in laser deposited tool alloy steel

    Energy Technology Data Exchange (ETDEWEB)

    Sun, G.F., E-mail: gfsun82@gmail.com [Center for Laser-Aided Intelligent Manufacturing, University of Michigan, Ann Arbor, MI, 48109 (United States); School of Mechanical Engineering, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Bhattacharya, S. [Center for Laser-Aided Intelligent Manufacturing, University of Michigan, Ann Arbor, MI, 48109 (United States); Dinda, G.P.; Dasgupta, A. [Center for Advanced Technologies, Focus: Hope, Detroit, MI, 48238 (United States); Mazumder, J. [Center for Laser-Aided Intelligent Manufacturing, University of Michigan, Ann Arbor, MI, 48109 (United States)

    2011-06-15

    Highlights: {yields} Orientation relationships among phases in the DMD are given. {yields} Martensite lattice parameters increased with laser specific energy. {yields} Austenite lattice parameters decreased with laser specific energy. - Abstract: Laser aided direct metal deposition (DMD) has been used to form AISI 4340 steel coating on the AISI 4140 steel substrate. The microstructural property of the DMD coating was analyzed by means of scanning electron microscopy, transmission electron microscopy and X-ray diffractometry. Microhardness of the DMD was measured with a Vickers microhardness tester. Results indicate that DMD can be used to form dense AISI 4340 steel coatings on AISI 4140 steel substrate. The DMD coating is mainly composed of martensite and retained austenite. Consecutive thermal cycles have a remarkable effect on the microstructure of the plan view of the DMD coating and on the corresponding microhardness distribution. Orientation relationships among austenite, martensite and cementite in the DMD coating followed the ones in conventional heat treated steels. As the laser specific energy decreased, cooling rate increased, and martensite peaks broadened and shifted to a lower Bragg's angle. Also martensite lattice parameters increased and austenite lattice parameters decreased due to the above parameter change.

  3. Modelling of Nb influence on phase transformation behaviours from austenite to ferrite in low carbon steels

    Science.gov (United States)

    Wang, L.; Parker, S. V.; Rose, A. J.; West, G. D.; Thomson, R. C.

    2016-03-01

    In this paper, a new model has been developed to predict the phase transformation behaviours from austenite to ferrite in Nb-containing low carbon steels. The new model is based on some previous work and incorporates the effects of Nb on phase transformation behaviours, in order to make it applicable for Nb-containing steels. Dissolved Nb atoms segregated at prior austenite grain boundaries increase the critical energy for ferrite nucleation, and thus the ferrite nucleation rate is decreased. Dissolved Nb atoms also apply a solute drag effect to the moving transformation interface, and the ferrite grain growth rate is also decreased. The overall transformation kinetics is then calculated according to the classic Johnson-Mehl-Avrami-Kolmogorov (JMAK) theory. The new model predictions are quite consistent with experimental results for various steels during isothermal transformations or continuous cooling.

  4. Influence of ferrite decomposition mechanisms on the corrosion resistance of an aged duplex stainless steel

    International Nuclear Information System (INIS)

    The effect of long term aging of a duplex stainless steel type X6 CrNiMoCu25-6 on pitting and intergranular corrosion was investigated by various electrochemical methods including cyclic potentiodynamic tests, potentio-kinetic tests and DL-EPR (Double Loop Electrochemical Potentio-kinetic Reactivation) tests. It was established that the spinodal decomposition of ferrite (α' + G) after aging at 400 C during 1000 h leads to localized chromium depletion (wavelength 20 nm) without any detrimental effect on the pitting and intergranular resistance of this steel in synthetic sea water, compared to the annealed steel. However, aging at 500 C for 1000 h generates carbides and intermetallic phases by nucleation and growth producing larger chromium depleted areas, which results in lower pitting and intergranular corrosion resistance in synthetic sea water. (authors)

  5. Influence of vanadium on static recrystallization in warm worked microalloyed steels

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Mateo, C.; Lopez, B.; Rodriguez-Ibabe, J.M.

    1999-12-31

    Warm forging of steels, in the range from 600 to 900 C, offers some important advantages over traditional forging procedures, with a better dimensional accuracy as well as surface quality in comparison with hot forging, and lower flow stress and therefore lower press loads in comparison with cold forging. It is well established that in hot working of V microalloyed steels, the vanadium in solid solution has a little effect on the static recrystallization kinetics between passes. In contrast, if strain induced precipitation takes place the static recrystallization is notably modified. The objective of this work is to study the effects that the application of warm working can have on the austenite static recrystallization process of vanadium microalloyed steels, considering a range of temperatures in which different precipitate volume fractions can remain undissolved in the austenite prior to deformation. The static recrystallization kinetics were determined by stress relaxation tests following the deformation by plain strain compression.

  6. Influence of Heat Treatment on the Corrosion of Microalloyed Steel in Sodium Chloride Solution

    Directory of Open Access Journals (Sweden)

    Asiful Hossain Seikh

    2013-01-01

    Full Text Available Microalloyed Steels find wide application in car bodies and other engineering parts because of its high strength as well as high ductility. Very fine grained microstructure is the reason behind the combination of strength and ductility. It has been reported that repeated quenching leads to further refining of microstructure. In the present investigation, corrosion resistance property of E34 microalloy steel has been studied in 3.5% NaCl solution in different microstructural conditions such as the as rolled one and three repeated quenched conditions. Weight loss, potentiodynamic polarization method, and electrochemical impedance spectroscopy (EIS techniques have been used. To reveal the corrosion resistance of different treated steels, some significant characterization parameters such as Ecorr, Icorr, Rp, and Rct in linear polarization and EIS curves were analyzed and compared. It is found that with repeated recrystallization grains become finer, and corrosion rate increases suggesting that a compromise has to strike between high mechanical property and corrosion rate.

  7. Fatigue Property of Open-Hole Steel Plates Influenced by Bolted Clamp-up and Hole Fabrication Methods

    Directory of Open Access Journals (Sweden)

    Zhi-Yu Wang

    2016-08-01

    Full Text Available Steel plates with open holes are commonly used in structural assemblies. The fatigue properties of such details are influenced by bolted clamp-up and hole fabrication methods. The fracture surface, stiffness degradation and fatigue life of test specimens are investigated in detail and compared with the contemporary test data. The analysis results show that the presence of draglines greatly influences the fatigue crack initiation at the open-hole cut by laser. The bolted clamp-up condition greatly enhances the stiffness and the fatigue life of the open-hole details. A discussion is also made from a comparison with the referred fatigue life of hole fabrication details, such as the influence of plate thickness and plasma cutting, drilling and oxy-fuel gas cutting, with the details studied herein. This work could enhance the understanding of the fatigue property and design of such details.

  8. The influence of aluminum and carbon on the abrasion resistance of high manganese steels

    Science.gov (United States)

    Buckholz, Samuel August

    Abrasive wear testing of lightweight, austenitic Fe-Mn-Al-C cast steel has been performed in accordance with ASTM G65 using a dry sand, rubber wheel, abrasion testing apparatus. Testing was conducted on a series of Fe-30Mn-XAl-YC-1Si-0.5Mo chemistries containing aluminum levels from 2.9 to 9.5 wt.% and carbon levels from 0.9 to 1.83 wt.%. Solution treated materials having an austenitic microstructure produced the highest wear resistance. Wear resistance decreased with higher aluminum, lower carbon, and higher hardness after age hardening. In the solution treated condition the wear rate was a strong function of the aluminum to carbon ratio and the wear rate increased with a parabolic dependence on the Al/C ratio, which ranged from 1.8 to 10.2. Examination of the surface wear scar revealed a mechanism of plowing during abrasion testing and this method of material removal is sensitive to work hardening rate. Work hardening behavior was determined from tensile tests and also decreased with increasing Al/C ratio and after aging hardening. The loss of wear resistance is related to short range ordering of Al and C in the solution treated materials and kappa-carbide precipitation in age hardened materials and both contribute to planar slip and lower work hardening rates. A high carbon tool steel (W1) and a bainitic low alloy steel (SAE 8620) were also tested for comparison. A lightweight steel containing 6.5 wt.% Al and 1.2 wt.% C has wear resistance comparable to within 5% of the bainitic SAE 8620 steel forging currently used for the Bradley Fighting Vehicle track shoe and this cast Fe-Mn-Al-C steel, at equivalent tensile properties, would be 10% lighter.

  9. Extracellular Electron Transfer Is a Bottleneck in the Microbiologically Influenced Corrosion of C1018 Carbon Steel by the Biofilm of Sulfate-Reducing Bacterium Desulfovibrio vulgaris.

    Directory of Open Access Journals (Sweden)

    Huabing Li

    Full Text Available Carbon steels are widely used in the oil and gas industry from downhole tubing to transport trunk lines. Microbes form biofilms, some of which cause the so-called microbiologically influenced corrosion (MIC of carbon steels. MIC by sulfate reducing bacteria (SRB is often a leading cause in MIC failures. Electrogenic SRB sessile cells harvest extracellular electrons from elemental iron oxidation for energy production in their metabolism. A previous study suggested that electron mediators riboflavin and flavin adenine dinucleotide (FAD both accelerated the MIC of 304 stainless steel by the Desulfovibrio vulgaris biofilm that is a corrosive SRB biofilm. Compared with stainless steels, carbon steels are usually far more prone to SRB attacks because SRB biofilms form much denser biofilms on carbon steel surfaces with a sessile cell density that is two orders of magnitude higher. In this work, C1018 carbon steel coupons were used in tests of MIC by D. vulgaris with and without an electron mediator. Experimental weight loss and pit depth data conclusively confirmed that both riboflavin and FAD were able to accelerate D. vulgaris attack against the carbon steel considerably. It has important implications in MIC failure analysis and MIC mitigation in the oil and gas industry.

  10. Microbiologically influenced corrosion of stainless steel tubing and piping in the service water system at North Anna Nuclear Power Station

    International Nuclear Information System (INIS)

    Since original plant construction in the 1970's, the carbon steel piping of the service water system (SWS) of Virginia Power's North Anna Nuclear Power Station has experienced general corrosion and pitting due to microbiologically influenced corrosion (MIC). Corrosion of the carbon steel piping was combatted by the implementation of chemical treatment of the SWS and by repair/replacement of portions of the piping utilizing type 316L stainless steel (SS) on 10 in. and smaller piping and 100% solids epoxy coating on the rest of the piping. Only recently, in early 1994, MIC was discovered on the 18 gage 304 S welded tubes in the Component Cooling Heat Exchangers (CCHXs). Earlier, MIC was discovered on 316L SS pipe base metal adjacent to several socket weld locations on small diameter piping. This paper will concentrate on the Virginia Power action plan to combat further degradation due to MIC and to maintain operable SS piping and equipment with SS tubing which is exposed to service water

  11. Influence of phosphorus content and quenching/tempering temperatures on fracture toughness and fatigue life of SAE 5160 steel

    Directory of Open Access Journals (Sweden)

    Danilo Borges Villarino de Castro

    2010-12-01

    Full Text Available This study investigates the influence of quenching/tempering temperatures on the fracture toughness and fatigue life of SAE 5160 steel, considering different phosphorus contents. Quenching and tempering treatments were applied to samples removed from different bars of commercial SAE 5160 steel with different P content. Three different austenitizing temperatures for quenching: 850, 900 and 1000 ºC and a constant holding time of 15 minutes were used. The oil temperature for quenching was kept at 66 ºC and the tempering conditions were 470, 500 and 530 ºC with the necessary time for a final hardness of 45 ± 3 HRC. Therefore, the heat treatments cycles were applied to specimens containing low (0.012 wt. (%, medium (0.017 wt. (% and high (above 0.025 wt. (% phosphorus contents, in order to observe the effects of this element on the susceptibility of these steels to enhance quench and tempering embrittlements. The Charpy tests results showed that the phosphorus content analyzed in this work has caused embrittlement, even in the bars with the lowest P content, leading to intergranular fracture. However, if the nucleation life is taken into consideration, this embrittlement has no effect on the nucleation fatigue life of the component.

  12. Microbially Influenced Corrosion of 304 Stainless Steel and Titanium by P. variotii and A. niger in Humid Atmosphere

    Science.gov (United States)

    Zhang, Dawei; Zhou, Feichi; Xiao, Kui; Cui, Tianyu; Qian, Hongchong; Li, Xiaogang

    2015-07-01

    Microbially induced corrosion (MIC) poses significant threats to reliability and safety of engineering materials and structures. While most MIC studies focus on prokaryotic bacteria such as sulfate-reducing bacteria, the influence of fungi on corrosion behaviors of metals has not been adequately reported. In this study, 304 stainless steel and titanium were exposed to two very common fungi, Paecilomyces variotii, Aspergillus niger and their mixtures under highly humid atmosphere. The initial corrosion behaviors within 28 days were studied via scanning Kelvin probe, which showed marked surface ennoblement and increasingly heterogeneous potential distribution upon prolonged fungus exposure. Using stereomicroscopy, fungus growth as well as corrosion morphology of 304 stainless steel and titanium were also evaluated after a long-term exposure for 60 days. The presence of fungi decreased the corrosion resistance for both 304 stainless steel and titanium. Titanium showed higher resistance to fungus growth and the induced corrosion. Exposure to the mixed strains resulted in the highest fungus growth rate but the mildest corrosion, possibly due to the decreased oxygen level by increased fungal activities.

  13. INFLUENCE OF CARBON CONTENT OF MARTENSITE STEELS ON HARDNESS RE-DISTRIBUTION NEAR WORN SURFACE

    Institute of Scientific and Technical Information of China (English)

    Y.P. Ma

    2002-01-01

    After three-body abrasion, the hardness re-distribution near the worn surface has aclose relationship with the carbon content of martensite steel. It is considered thatthere is a competition between the work-hardening and the temper softening, whichresults from deformation and friction heat of material. When the carbon content ofmartensite steel is below about 0.6%, the subsurface hardness distribution of materialis a softened layer sandwiched between two hardened layers, but above 0.6%C, nosoftened region appears on the hardness re-distribution curve.

  14. Influence of cooling intensity on the structure formation in stripe steel by thermomechanical treatment

    OpenAIRE

    Goryany V.; Khlyntseva T.; Mamuzić I.; Radsinsky V.

    2004-01-01

    The results of research of microstructure of the strips from low carbon steel 45x6 and 30x8 mm in hot-rolling condition and after accelerated cooling of different intencity and schemes of the coolers movement in the cooling chambers are shown. The strengthening layer is spread unevenly along the perimeter of the rolled steel. The formation character of the structure and its spreading along the cross-section depends on intensity of cooling and the ratio of the width of the stripe to its thickn...

  15. Influence of Impact Energy on Impact Corrosion-abrasion of High Manganese Steel

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The impact corrosion-abrasion properties and mechanism of high manganese steel were investigated under different impact energies. The result shows that the wearability of the steel decreases with the increase of the impact energy. The dominant failure mechanism at a lower impact energy is the rupture of extrusion edge along root and a slight shallow-layer spalling. It transforms to shallow-layer fatigue flaking along with serious corrosion-abrasion when the impact energy is increased, and finally changes to bulk flaking of hardened layer caused by deep work-hardening and heavy corrosion-abrasion.

  16. THE VERIFICATION OF THE INFLUENCE OF HEATING STEEL CHARGE PARAMETERS ON THE THICKNESS OF SCALE LAYER

    Directory of Open Access Journals (Sweden)

    Agnieszka Benduch

    2013-06-01

    Full Text Available Parameters of heating are understood as the conditions in which heating process is conducted to obtain the required steel properties. During the heating process, on the surface of heated elements, layer of scale is formed as a by-product,. The selection of appropriate heating parameters allows for achieving the required layer of scale, and thus the predictability of the process effects . The article presents sample calculations of heating parameters for the charge of steel and the analysis of the results of conducted experiments.

  17. Influence Of Heat Treatment On Duplex Stainless Steel To Study The Material Properties

    Directory of Open Access Journals (Sweden)

    Jithin M

    2015-02-01

    Full Text Available Abstract The various heat treatment processes are annealing normalizing hardening tempering spheroidising surface hardening flame and induction hardening nitriding cyaniding carbonitriding carburizing etc Heat treatment on duplex stainless steel is to improve ductility toughness strength hardness and to relieve internal stress developed in the material. Here basically the experiment of hardness test impact test wear test and compression is done to get idea about heat treated duplex stainless steel which has extensive uses in all industries and scientific research and development fields.

  18. Influence Of Tool Geometry, Tool Coating And Process Parameters In Thixoextrusion Of Steel

    International Nuclear Information System (INIS)

    Thixoextrusion could become one possibility to enlarge the complexity of extruded profiles made of steel. Accordingly semi-solid extrusion experiments of X210CrW12 tool steel using round dies of approximately 15 mm diameter were performed in order to achieve first information concerning possible process windows and process limits. For liquid fractions between 38% and 10%, extrusion press velocities from 10 mm/s to 50 mm/s and dies with novel PVD-coatings no complete solidification during extrusion was achieved. However the collected pieces of the extruded bars showed a fine and evenly distributed globular microstructure

  19. Low friction slip-rolling contacts. Influences of alternative steels, high performance thin film coatings and lubricants

    Energy Technology Data Exchange (ETDEWEB)

    Scholz, Christian

    2013-02-01

    and NC310YW (Aubert and Duval) as well as CSS-42L (Latrobe Specialty Steel Company), in combination with thin film coatings, even if they compete in the uncoated state, the Hertzian contact pressures could be increased up to P{sub 0max} = 4.2 GPa (F{sub N} = 5,000 N) without any surface failures of coating or substrate. It was shown that selected thin film coatings can minimize the wear rates down to nearly 'zero-wear' in highly stressed contacts [Woy08] [Woy11]. In addition, the studies revealed not only the high potential in slip-rolling resistance, but also a possible friction reduction down to 0.047 by use of uncoated steels with increased toughness. Compared to steels like 100Cr6H and Cronidur 30 this means a reduction in friction of approximately 40% under identical testing conditions. Different test series with newly developed base oil-additive formulations were investigated with specific emphasis on the frictional behavior of selected bio-no-tox EP/AW additives and friction modifiers. Additional influencing factors like the structural and surface conditions of the steels/coatings before and after the tests were analyzed by means of REM, EDX, XRD and TEM.

  20. The influence of the martensitic transformation on the fatigue of an AISI type 316 metastable stainless steel

    International Nuclear Information System (INIS)

    The influence of the martensitic transformation on the process of pulse tension fatigue of a AISI type 316 metastable stainless steel was studied at 250 and 1960c. The fatigue tests were performed on annealed and cold worked specimens in order to separate the effects of static transformation, dynamic transformation and work hardening. The fatigue limits obtained from the corresponding Wohler curves were compared for the different test conditions. The results showed that the fatigue is not affected by the dynamically induced martensite. On the other hand the static martensite, previously induced, appears to decrease the resistance to fatigue. The reasons for these effects are discussed. (Author)

  1. Materials Selection Criteria for Nuclear Power Applications: A Decision Algorithm

    Science.gov (United States)

    Rodríguez-Prieto, Álvaro; Camacho, Ana María; Sebastián, Miguel Ángel

    2016-02-01

    An innovative methodology based on stringency levels is proposed in this paper and improves the current selection method for structural materials used in demanding industrial applications. This paper describes a new approach for quantifying the stringency of materials requirements based on a novel deterministic algorithm to prevent potential failures. We have applied the new methodology to different standardized specifications used in pressure vessels design, such as SA-533 Grade B Cl.1, SA-508 Cl.3 (issued by the American Society of Mechanical Engineers), DIN 20MnMoNi55 (issued by the German Institute of Standardization) and 16MND5 (issued by the French Nuclear Commission) specifications and determine the influence of design code selection. This study is based on key scientific publications on the influence of chemical composition on the mechanical behavior of materials, which were not considered when the technological requirements were established in the aforementioned specifications. For this purpose, a new method to quantify the efficacy of each standard has been developed using a deterministic algorithm. The process of assigning relative weights was performed by consulting a panel of experts in materials selection for reactor pressure vessels to provide a more objective methodology; thus, the resulting mathematical calculations for quantitative analysis are greatly simplified. The final results show that steel DIN 20MnMoNi55 is the best material option. Additionally, more recently developed materials such as DIN 20MnMoNi55, 16MND5 and SA-508 Cl.3 exhibit mechanical requirements more stringent than SA-533 Grade B Cl.1. The methodology presented in this paper can be used as a decision tool in selection of materials for a wide range of applications.

  2. Influence of flowing sodium on the creep properties of ferritic steel R8 (EM 12)

    International Nuclear Information System (INIS)

    Uniaxial creep rupture tests have been performed on the ferritic steel R8 (type EM12) both in vacuum and in flowing sodium. The effect of sodium exposure on the creep parameters is discussed in terms of the structural and chemical changes observed. The role played by non-metallic and metallic impurities is treated in more detail. (orig.)

  3. Influence of Citric Acid on the Metal Release of Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Mazinanian, N.; Wallinder, I. Odnevall; Hedberg, Y. S. [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, Stockholm (Sweden)

    2015-08-15

    Knowledge of how metal releases from the stainless steels used in food processing applications and cooking utensils is essential within the framework of human health risk assessment. A new European standard test protocol for testing metal release in food contact materials made from metals and alloys has recently been published by the Council of Europe. The major difference from earlier test protocols is the use of citric acid as the worst-case food simulant. The objectives of this study were to assess the effect of citric acid at acidic, neutral, and alkaline solution pH on the extent of metal release for stainless steel grades AISI 304 and 316, commonly used as food contact materials. Both grades released lower amounts of metals than the specific release limits when they were tested according to test guidelines. The released amounts of metals were assessed by means of graphite furnace atomic absorption spectroscopy, and changes in the outermost surface composition were determined using X-ray photoelectron spectroscopy. The results demonstrate that both the pH and the complexation capacity of the solutions affected the extent of metal release from stainless steel and are discussed from a mechanistic perspective. The outermost surface oxide was significantly enriched in chromium upon exposure to citric acid, indicating rapid passivation by the acid. This study elucidates the effect of several possible mechanisms, including complex ion- and ligand-induced metal release, that govern the process of metal release from stainless steel under passive conditions in solutions that contain citric acid.

  4. Influence of NaCl Deposition on Atmospheric Corrosion of A3 Steel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Regularity of the initial atmospheric corrosion of A3 steel in the presence of NaCl was investigated. The results showed that NaCl can accelerate the corrosion of A3 steel. Dry mass gain of A3 steel in the presence of NaCl deposition increases with the exposure time, which can be correlated by using exponential decay function. The relationship between dry mass gain and amount of NaCl deposition at a certain exposure time follows a quadratic function. More amount of NaCl deposition will slow down the corrosion rate to some extent after exposure for a certain time. SEM/EDAX was used to characterize the corrosion surface and products. The surfaces of the NaCl treated A3 steel were obviously uneven, and some tiny crevices appear in the corrosion products that could help O2 transmit to the inner layer. The amount of oxygen in atomic percentage in the corrosion products increases with the amount of NaCl deposition.

  5. Influence of surface texture on the galling characteristics of lean duplex and austenitic stainless steels

    DEFF Research Database (Denmark)

    Wadman, Boel; Eriksen, J.; Olsson, M.;

    2010-01-01

    Two simulative test methods were used to study galling in sheet forming of two types of stainless steel sheet: austenitic (EN 1.4301) and lean duplex LDX 2101 (EN 1.4162) in different surface conditions. The pin-on-disc test was used to analyse the galling resistance of different combinations...

  6. Influence Of Large Non-Metallic Inclusions On Bending Fatigue Strength Hardened And Tempered Steels

    Directory of Open Access Journals (Sweden)

    Lipiński T.

    2015-09-01

    Full Text Available The article discusses the effect of large oxide impurities (a diameter larger than 10 μm in size on the fatigue resistance of structural steel of high purity during rotary bending. The study was performed on 7 heats produced in an industrial plant. The heats were produced in 140 ton electric furnaces. All heats were desulfurized.

  7. Influence of surface oxides on the hydrogen permeability of steels at room and medium temperatures

    International Nuclear Information System (INIS)

    Up- and/or down-stream faces of typical steels disks are naturally or purposedly oxidized, cleaned by hot H2 or Pd-coated prior to their exposure to D2 or T2, under various stresses. Strategically selected permeation and outgassing tests enable to illustrate the monitoring processes and their relative importance

  8. The influence of tooth preparation and crown manipulation on the mechanical retention of stainless steel crowns.

    Science.gov (United States)

    Rector, J A; Mitchell, R J; Spedding, R H

    1985-01-01

    The belief that close adaptation of the metal margins to tooth surfaces in the undercut areas is the most important retentive feature, was borne out in this study. The type of preparation did not affect the retention of stainless steel crowns.

  9. Influence of Ni-electrodeposited Pretreatment on Galvanized Coatings of Reactive Steels

    Institute of Scientific and Technical Information of China (English)

    CHE Chunshan; LU Jingtang; KONG Gang; XU Qiaoyu; SUI Runzhou

    2007-01-01

    Four types of steel sheets containing 0.04%, 0.09%, 0.14% and 0.36% Si, respectively, were electrodeposited with a nickel layer of 3 μm in thickness and then galvanized in molten Zn at 450℃ for various periods of time. The formation and growth of intermetallic compound layers on the surface of the samples were investigated by SEM and EDS. The experimental results show that the method of Ni-electrodeposited pretreatment can distinctively restrain the over-growth of the galvanized coatings of reactive steels and get eligible coatings with a proper thickness, bright appearance and strong adherence. EDS results indicate that a series of Ni-Zn intermetallic compounds γ',γ and δ2 are first formed on the surface of the samples. With a prolonged immersion time, the Г2-Fe-Zn-Ni and δ-Fe-Zn are formed accompanied by the gradual disappearance of γ',γ and δ2 layer. After a longer immersion time, the lumpy ζ- Fe-Zn occurs between δ and liquid Zn and the Г-Fe-Zn does between steel substrate and δ. Subsequently, ζ is in the form of a continuous and compact layer. The method of Ni-electrodeposited pretreatment changes the formation of Fe-Zn intermetallic compounds, which delay the growth of lumpy ζ and promote the growth of compact δ. Consequently, the abnormal growth of reactive steels is eliminated.

  10. Influence of burnishing on stress corrosion cracking susceptibility of duplex steel

    Directory of Open Access Journals (Sweden)

    J. Łabanowski

    2006-09-01

    Full Text Available Purpose: of the current study was to investigate the usability of burnishing-inducted surface enhancement method for improve the stress corrosion cracking resistance of duplex stainless steel.Design/methodology/approach: The surface layers upon round in cross section specimens were performed through burnishing treatment. Corrosion tests were performed with the use of Slow Strain Rate Test technique in inert (glycerin and aggressive (boiling 35% MgCl2 solution environments.Findings: It was shown that burnishing treatment increases corrosion resistance of the steel. Stress corrosion cracking resistance depends on the magnitude of cold work at surface layers. High level of cold work decreases corrosion resistance.Research limitations/implications: This study does not indicate the optimum stress level and stress distribution in surface layers for the best corrosion resistance. It is necessary to continue the research to determine burnishing parameters for demanded properties of duplex steel surface layers.Practical implications: The burnishing treatment can significantly improve stress corrosion resistance of specified parts of chemical installations working in the contact with aggressive media. Such parts as valve parts or propeller shafts can be successfully protected against corrosion attack.Originality/value: Burnishing surface enhancement for constructional parts made of duplex stainless steels exposed to corrosive environments has not been reported in literature. Application of this technology can increase life-time of chemical installation devices and improve their reliability.

  11. Stainless steels with low contents in residual elements for nitric acid environments. Influence of melting processes

    International Nuclear Information System (INIS)

    Nitric acid solutions, as they are for instance employed in the chemical treatment of nuclear fuels, do not apparently pose any more corrosion problems and the safe use of the several steels is well documented. The most difficult corrosion problems are next those related to ''tunnel'' penetrations, in the hot-rolling direction (longitudinal). This phenomenon can be quite important such as to imperial complex structures. Up to the last few years, the only manner to eliminate such ''tunnel'' corrosions was to carry out special operations of remelting and refining under careful selected slag (Electro Slag Remelting or ESR). It turns out indeed that non metallic inclusions are the prime factors in this type of corrosion. Well adapted ladle refining processes made possible to obtain equivalent results at lower costs, while purity and cleanliness are improved to such a degree that a steel of type Cr 18 - Ni 10 thus produced exhibit a nearly absolute resistance to intergranular corrosion in the 14 N (65%) boiling nitric acid (the Huey test) whatever the ''sensitization'' treatment, between 10000C and 6000C. In view of its very high tolerance to varied thermal cycles and of the near complete disappearance of any ''tunnel'' corrosion, such a steel is of great interest when complex parts are produced, by machining forged or rolled metal, which is then assembled by welding techniques or procedures which would be forbidden in the case of usual Cr 18 -Ni 10 steels. Similar improvements are also obtained on the two other special steels used in nitric environments: Cr 25 - Ni 20 - C <= 0,020 (Nb) and Cr 17 - Ni 14 - Si 4 - C <= 0,015 (Nb)

  12. Normal Force Influence on 3D Texture Parameters Characterizing the Friction Couple Steel – PBT + 10 % PTFE

    Directory of Open Access Journals (Sweden)

    C. Georgescu

    2014-03-01

    Full Text Available This study presents the influence of the normal force on the surface quality of the friction couple steel – polybutylene terephthalate (PBT + 10 % polytetrafluoroethylene (PTFE. There were calculated the average values of the amplitude and functional parameters, as obtained from investigating square areas on the wear tracks, with the help of a proposed methodology, for initial and tested surfaces generated on the blocks and on counterpart ring made of rolling bearing steel, for the following test conditions: three normal forces (F = 1 N, F = 2.5 N and F =5 N, three sliding speeds (v = 0.25 m/s, v = 0.50 m/s and v = 0.75 m/s and a sliding distance of L = 7500 m. The conclusion of the research study was that the tested normal force range has an insignificant influence on the surface quality for the tested materials and parameters. This friction couple could be recommended for variable conditions (speed and load in dry regimes.

  13. Influence of Sulfate-Reducing Bacteria on the Corrosion Behavior of High Strength Steel EQ70 under Cathodic Polarization

    Science.gov (United States)

    Guan, Fang; Zhai, Xiaofan; Duan, Jizhou; Zhang, Meixia; Hou, Baorong

    2016-01-01

    Certain species of sulfate-reducing bacteria (SRB) use cathodes as electron donors for metabolism, and this electron transfer process may influence the proper protection potential choice for structures. The interaction between SRB and polarized electrodes had been the focus of numerous investigations. In this paper, the impact of cathodic protection (CP) on Desulfovibrio caledoniens metabolic activity and its influence on highs trength steel EQ70 were studied by bacterial analyses and electrochemical measurements. The results showed that EQ70 under -0.85 VSCE CP had a higher corrosion rate than that without CP, while EQ70 with -1.05 VSCE had a lower corrosion rate. The enhanced SRB metabolic activity at -0.85 VSCE was most probably caused by the direct electron transfer from the electrode polarized at -0.85 VSCE. This direct electron transfer pathway was unavailable in -1.05 VSCE. In addition, the application of cathodic protection led to the transformation of sulfide rusts into carbonates rusts. These observations have been employed to provide updated recommendations for the optimum CP potential for steel structures in the presence of SRB. PMID:27603928

  14. Investigation of the Influence Factors on Distortion in Induction-Hardened Steel Shafts Manufactured from Cold-Drawn Rod

    Science.gov (United States)

    Dong, Juan; Epp, Jeremy; Rocha, Alexandre da Silva; Nunes, Rafael Menezes; Zoch, Hans Werner

    2016-02-01

    In this study, the distortion of steel shafts was investigated before and after induction hardening. Several essential influencing factors in the manufacturing process chain regarding cold drawing, cutting method, notches on the shafts, and induction hardening were analyzed by design of experiment (DoE). Further necessary examinations of microstructures, hardness profile, segregation of chemical composition, and residual stress state were conducted for understanding the distortion behavior. The results of the statistical analysis of the DoE showed that the drawing process is the most important factor influencing distortion. The surface hardening depth of induction hardening is the second main factor. The relationship between inhomogeneities in the work pieces and the distortion was finally discussed.

  15. Microbially influenced corrosion on stainless steels in natural seawater; Kaisuichu ni okeru sutenresu ko no biseibutsu fushoku

    Energy Technology Data Exchange (ETDEWEB)

    Amaya, H.; Miyuki, H. [Sumitomo Metal Industries Ltd., Osaka (Japan)

    1995-04-05

    The influence of microbes on the corrosion of steels in natural seawater is introduced laying stress on elucidated points. Biofilm consisting of various kinds of microbes is formed on the surface immersed in natural seawater. Adhered bacteria in this biofilm are isolated, and corrosion potential (Ecorr) in an experimental pure cultured system has been also investigated. Metabolic reaction of bacteria plays a part in microbially influenced corrosion (MIC), and reproduction of ennoblement of Ecorr is attempted by artificial means which simulates the breathing reaction of bacteria using refined oxidizing enzyme. It is made clear that corrosion behavior in natural seawater can be reproduced experimentally in a short period of time. This test method simulates the environment of the actual natural seawater well, and environmental MIC can be easily reproduced, which has been difficult in tests where conventional isolated bacteria are employed. 32 refs., 6 figs., 2 tabs.

  16. Influence of Plastic Deformation on Low-Temperature Surface Hardening of Austenitic Stainless Steel by Gaseous Nitriding

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas Lundin;

    2015-01-01

    This article addresses an investigation of the influence of plastic deformation on low-temperature surface hardening by gaseous nitriding of two commercial stainless steels: EN 1.4369 and AISI 304. The materials were plastically deformed to several levels of equivalent strain by conventional...... tensile straining, plane strain compression, and shear. Gaseous nitriding of the strained material was performed in ammonia gas at atmospheric pressure at various temperatures. Microstructural characterization of the as-deformed state and the nitrided case produced included X-ray diffraction analysis......, reflected-light microscopy, and microhardness testing. The results demonstrate that a case of expanded austenite develops and that the presence of plastic deformation has a significant influence on the morphology of the nitrided case. The presence of strain-induced martensite favors the formation of Cr...

  17. Use of Homogeneously-Sized Carbon Steel Ball Bearings to Study Microbially-Influenced Corrosion in Oil Field Samples.

    Science.gov (United States)

    Voordouw, Gerrit; Menon, Priyesh; Pinnock, Tijan; Sharma, Mohita; Shen, Yin; Venturelli, Amanda; Voordouw, Johanna; Sexton, Aoife

    2016-01-01

    Microbially-influenced corrosion (MIC) contributes to the general corrosion rate (CR), which is typically measured with carbon steel coupons. Here we explore the use of carbon steel ball bearings, referred to as beads (55.0 ± 0.3 mg; Ø = 0.238 cm), for determining CRs. CRs for samples from an oil field in Oceania incubated with beads were determined by the weight loss method, using acid treatment to remove corrosion products. The release of ferrous and ferric iron was also measured and CRs based on weight loss and iron determination were in good agreement. Average CRs were 0.022 mm/yr for eight produced waters with high numbers (10(5)/ml) of acid-producing bacteria (APB), but no sulfate-reducing bacteria (SRB). Average CRs were 0.009 mm/yr for five central processing facility (CPF) waters, which had no APB or SRB due to weekly biocide treatment and 0.036 mm/yr for 2 CPF tank bottom sludges, which had high numbers of APB (10(6)/ml) and SRB (10(8)/ml). Hence, corrosion monitoring with carbon steel beads indicated that biocide treatment of CPF waters decreased the CR, except where biocide did not penetrate. The CR for incubations with 20 ml of a produced water decreased from 0.061 to 0.007 mm/yr when increasing the number of beads from 1 to 40. CRs determined with beads were higher than those with coupons, possibly also due to a higher weight of iron per unit volume used in incubations with coupons. Use of 1 ml syringe columns, containing carbon steel beads, and injected with 10 ml/day of SRB-containing medium for 256 days gave a CR of 0.11 mm/yr under flow conditions. The standard deviation of the distribution of residual bead weights, a measure for the unevenness of the corrosion, increased with increasing CR. The most heavily corroded beads showed significant pitting. Hence the use of uniformly sized carbon steel beads offers new opportunities for screening and monitoring of corrosion including determination of the distribution of corrosion rates, which allows

  18. Use of Homogeneously-Sized Carbon Steel Ball Bearings to Study Microbially-Influenced Corrosion in Oil Field Samples

    Directory of Open Access Journals (Sweden)

    Gerrit eVoordouw

    2016-03-01

    Full Text Available Microbially-influenced corrosion (MIC contributes to the general corrosion rate (CR, which is typically measured with carbon steel coupons. Here we explore the use of carbon steel ball bearings, referred to as beads (55.0 ± 0.3 mg; Ø = 0.238 cm, for determining CRs. CRs for samples from an oil field in Oceania incubated with beads were determined by the weight loss method, using acid treatment to remove corrosion products. The release of ferrous and ferric iron was also measured and CRs based on weight loss and iron determination were in good agreement. Average CRs were 0.022 mm/yr for 8 produced waters with high numbers (105/ml of acid-producing bacteria (APB, but no sulfate-reducing bacteria (SRB. Average CRs were 0.009 mm/yr for 5 central processing facility (CPF waters, which had no APB or SRB due to weekly biocide treatment and 0.036 mm/yr for 2 CPF tank bottom sludges, which had high numbers of APB (106/ml and SRB (108/ml. Hence, corrosion monitoring with carbon steel beads indicated that biocide treatment of CPF waters decreased the CR, except where biocide did not penetrate. The CR for incubations with 20 ml of a produced water decreased from 0.061 to 0.007 mm/yr when increasing the number of beads from 1 to 40. CRs determined with beads were higher than those with coupons, possibly also due to a higher weight of iron per unit volume used in incubations with coupons. Use of 1 ml syringe columns, containing carbon steel beads and injected with 10 ml/day of SRB-containing medium for 256 days gave a CR of 0.11 mm/yr under flow conditions. The standard deviation of the distribution of residual bead weights, a measure for the unevenness of the corrosion, increased with increasing CR. The most heavily corroded beads showed significant pitting. Hence the use of uniformly sized carbon steel beads offers new opportunities for screening and monitoring of corrosion including determination of the distribution of corrosion rates, which allows

  19. Use of Homogeneously-Sized Carbon Steel Ball Bearings to Study Microbially-Influenced Corrosion in Oil Field Samples

    Science.gov (United States)

    Voordouw, Gerrit; Menon, Priyesh; Pinnock, Tijan; Sharma, Mohita; Shen, Yin; Venturelli, Amanda; Voordouw, Johanna; Sexton, Aoife

    2016-01-01

    Microbially-influenced corrosion (MIC) contributes to the general corrosion rate (CR), which is typically measured with carbon steel coupons. Here we explore the use of carbon steel ball bearings, referred to as beads (55.0 ± 0.3 mg; Ø = 0.238 cm), for determining CRs. CRs for samples from an oil field in Oceania incubated with beads were determined by the weight loss method, using acid treatment to remove corrosion products. The release of ferrous and ferric iron was also measured and CRs based on weight loss and iron determination were in good agreement. Average CRs were 0.022 mm/yr for eight produced waters with high numbers (105/ml) of acid-producing bacteria (APB), but no sulfate-reducing bacteria (SRB). Average CRs were 0.009 mm/yr for five central processing facility (CPF) waters, which had no APB or SRB due to weekly biocide treatment and 0.036 mm/yr for 2 CPF tank bottom sludges, which had high numbers of APB (106/ml) and SRB (108/ml). Hence, corrosion monitoring with carbon steel beads indicated that biocide treatment of CPF waters decreased the CR, except where biocide did not penetrate. The CR for incubations with 20 ml of a produced water decreased from 0.061 to 0.007 mm/yr when increasing the number of beads from 1 to 40. CRs determined with beads were higher than those with coupons, possibly also due to a higher weight of iron per unit volume used in incubations with coupons. Use of 1 ml syringe columns, containing carbon steel beads, and injected with 10 ml/day of SRB-containing medium for 256 days gave a CR of 0.11 mm/yr under flow conditions. The standard deviation of the distribution of residual bead weights, a measure for the unevenness of the corrosion, increased with increasing CR. The most heavily corroded beads showed significant pitting. Hence the use of uniformly sized carbon steel beads offers new opportunities for screening and monitoring of corrosion including determination of the distribution of corrosion rates, which allows

  20. Influence of cooling intensity on the structure formation in stripe steel by thermomechanical treatment

    Directory of Open Access Journals (Sweden)

    Goryany V.

    2004-01-01

    Full Text Available The results of research of microstructure of the strips from low carbon steel 45x6 and 30x8 mm in hot-rolling condition and after accelerated cooling of different intencity and schemes of the coolers movement in the cooling chambers are shown. The strengthening layer is spread unevenly along the perimeter of the rolled steel. The formation character of the structure and its spreading along the cross-section depends on intensity of cooling and the ratio of the width of the stripe to its thickness. Regimes, that provide the high level of steel’s strength with the smallest changing of the mechanical properties by the length of the rolled strip were defined.

  1. Analysis of the influence of electrolyte on surface finish in electropolished stainless steel

    Science.gov (United States)

    Hernando, M.; Núñez, P. J.; García, E.; Trujillo, R.

    2012-04-01

    Electropolishing is a surface finishing process of metals and alloys that enhances brilliant surface finishes with low surface roughness values. The most widely used electrolytes for the electropolishing of stainless steel are varying concentrations of phosphoric and sulphuric acid, and occasionally additives such as chromic acid. The objective of this study was to assess the performance of three commonly used industrial electrolytes in terms of the surface finish of electropolished stainless steel AISI 316L. Each electrolyte had varying sulphuric-phosphoric acid combinations with or without chromic acid. The following electropolishing conditions were assessed: current density, bath temperature, electropolishing time, and initial surface texture. The results revealed that adding chromic acid to the electrolyte did not significantly enhance surface finish, and electropolishing ranges were quite similar for all three electrolytes.

  2. The influence of fabricating conditions and stability of austenite on forming behaviour of austenitic stainless steels

    International Nuclear Information System (INIS)

    The object of the investigation is the effect of various conditions of cold rolling austenitic stainless steels on the mechanical and technological properties and on the behaviour during forming with requirements in stretching and deep drawing. Fabricating 3 coils of various stability of austenite the degree of cold forming between the annealing processes is varied by cold rolling from the thickness of hot rolled coil to final thickness without or with one or two intermediate annealings. The most important results for cold forming sheets are: most favourable stretch forming behaviour is gained with instable austenitic steels, becomes better with increasing sheet thickness most favourable deep drawing behaviour is gained with highest degrees of cold rolling before final annealing, is undependent from the stability of austenite. Favourable is cold rolling to the highest degree before intermediate annealing, whilst the deformation before final annealing is of greater importance. According to the results conditions can be given for cold rolling to get best forming behaviour. (orig.)

  3. Influence of Material Compressibility on Displacement Solution for Structural Steel Plate Applications

    Directory of Open Access Journals (Sweden)

    Nelli Aleksandrova

    2014-01-01

    Full Text Available Displacement field calculations are necessary for many structural steel engineering problems such as cold expansion of holes, embedment of bolts and rivets, and installation and maintenance of external devices. To this end, rigorous closed form analytical displacement solution is obtained for structural steel open-hole plates with in-plane loading. The material of the model is considered to be elastic perfectly plastic obeying the von Mises yield criterion with its associated flow rule. On the basis of this solution, two simplified engineering formulae are proposed and carefully discussed for practical engineering purposes. Graphical representations of results show validity of each formula as compared with rigorous solution and other studies.

  4. Influence of electrical Field on Pulsed Laser beam welding of Stainless Steel (304)

    OpenAIRE

    FAWZİ, Salah A. H.; ARİF, RAZ N.

    1999-01-01

    Pulsed laser beam welding experiment were carried out on stainless steel (SUS 304), using vertical and horizontal electric fields of different intensities to study its effectiveness on the welding process, regarding depth and weld quality. Pulsed Nd: YAG laser emitting 10 ms pulses in the TEM00 mode at 1.06 m m wave length was employed, microstructure of welded zone and defect were investigated using optical and scanning electron microscopes. Tensile test and microhardness measuremen...

  5. Influence of Texture and Microstructure Inhomogeneities on the Origin of Goss Texture in Silicon Steel

    OpenAIRE

    Seidel, L.; Lücke, K.

    1991-01-01

    Development of texture and microstructure of commercial high permeability silicon steel during rolling and recrystallization were studied by Orientation Distribution Functions (ODFs) and optical and electron microscopy. The present results confirm former single crystal results that large {111}-oriented cold rolled grains containing shear bands are the origin of the Goss texture after primary and secondary recrystallization. The formation of {111}-oriented grains during intermediate cold-rolli...

  6. The influence of heterogenous porosity on silicon nitride/steel wear in lubricated rolling contact

    OpenAIRE

    KANG, J; Hadfield, M

    2000-01-01

    Heterogeneous porosity is detected on the surface and subsurface of hot isostatically pressed (HIPed) silicon nitride spherical rolling elements. The extent of the localised porosity accounts for an area of 6% of the rolling element surface and 4% of the material volume. An experimental investigation using a rotary tribometer is described to compare the lubricated rolling wear mechanisms and performance of HIPed silicon nitride with heterogeneous porosity defect in contact with steel. A brief...

  7. Influences of passivating elements on the corrosion and biocompatibility of super stainless steels.

    Science.gov (United States)

    Yoo, Young-Ran; Jang, Soon-Geun; Oh, Keun-Taek; Kim, Jung-Gu; Kim, Young-Sik

    2008-08-01

    Biometals need high corrosion resistance since metallic implants in the body should be biocompatible and metal ion release should be minimized. In this work, we designed three kinds of super stainless steel and adjusted the alloying elements to obtain different microstructures. Super stainless steels contain larger amounts of Cr, Mo, W, and N than commercial alloys. These elements play a very important role in localized corrosion and, thus, their effects can be represented by the "pitting resistance equivalent number (PREN)." This work focused on the behavior which can arise when the bare surface of an implant in the body is exposed during walking, heavy exercise, and so on. Among the experimental alloys examined herein, Alloy Al and 316L stainless steels were mildly cytotoxic, whereas the other super austenitic, duplex, and ferritic stainless steels were noncytotoxic. This behavior is primarily related to the passive current and pitting resistance of the alloys. When the PREN value was increased, the passivation behavior in simulated body solution was totally different from that in acidic chloride solution and, thus, the Cr(2)O(3)/Cr(OH)(3) and [Metal oxide]/[Metal + Metal oxide] ratios of the passive film in the simulated body solution were larger than those in acidic chloride solution. Also, the critical current density in simulated body solution increased and, thus, active dissolution may induce metal ion release into the body when the PREN value and Ni content are increased. This behavior was closely related to the presence of EDTA in the simulated body solution. PMID:18161790

  8. Influence of burnishing on stress corrosion cracking susceptibility of duplex steel

    OpenAIRE

    J. Łabanowski; A. Ossowska

    2006-01-01

    Purpose: of the current study was to investigate the usability of burnishing-inducted surface enhancement method for improve the stress corrosion cracking resistance of duplex stainless steel.Design/methodology/approach: The surface layers upon round in cross section specimens were performed through burnishing treatment. Corrosion tests were performed with the use of Slow Strain Rate Test technique in inert (glycerin) and aggressive (boiling 35% MgCl2 solution) environments.Findings: It was s...

  9. Heat treatment influence on mechanical properties of structural steels for quenching and tempering

    OpenAIRE

    L.A. Dobrzański; R. Honysz

    2012-01-01

    Purpose: This paper introduces analysis results of heat treatment conditions inuence on mechanical properties of alloy structural steels for quenching and tempering.Design/methodology/approach: Investigations were performed in virtual environment with use of materials science virtual laboratory. Virtual investigations results were verified in real investigative laboratory.Findings: Performed verification investigations presented in this paper on selected mechanical properties modelling example...

  10. Influence of ultra-high strength infill in slender concrete-filled steel tubular columns

    OpenAIRE

    PORTOLES FLAJ, JOSÉ MANUEL; Serra Mercé, Enrique; Romero, Manuel L.

    2013-01-01

    This paper describes 24 tests conducted on slender circular tubular columns filled with normal, high, and ultra-high strength concrete for plain, bar reinforced and steel fiber reinforced columns. These were reinforced and subjected to both concentric and eccentric axial load. It is a continuation of a previous research paper (Portoles et al., 2011 [1]), which presented test results on eccentrically loaded plain concrete columns. The test parameters are nominal strength of concrete (30, 90...

  11. The Influence of heat treatment in orthodontic arches made of stainless steel wire

    Directory of Open Access Journals (Sweden)

    de Biasi R.S.

    2000-01-01

    Full Text Available The austenitic stainless steel of orthodontic wires may undergo phase transformation induced by plastic deformation and heat treatment for stress relief. In order to study these changes, arches were made with 0.0215 x 0.027" orthodontic wires and ferromagnetic resonance measurements were performed. The results showed that the best heat treatment for recovery of the austenitic phase seems to be at 450 °C for 3 min.

  12. Influence Of Heat Treatment On Duplex Stainless Steel To Study The Material Properties

    OpenAIRE

    Jithin M; Anees Abdul Hameed; Ben Jose; Anush Jacob

    2015-01-01

    Abstract The various heat treatment processes are annealing normalizing hardening tempering spheroidising surface hardening flame and induction hardening nitriding cyaniding carbonitriding carburizing etc Heat treatment on duplex stainless steel is to improve ductility toughness strength hardness and to relieve internal stress developed in the material. Here basically the experiment of hardness test impact test wear test and compression is done to get idea about heat treated duplex stainless ...

  13. Influence of Strain-rate Effects on the Analysis of Steel Sections under Blast Loads

    OpenAIRE

    KARLOS VASILEIOS; SOLOMOS George

    2014-01-01

    The response of structural steel components under explosive loading is numerically investigated. First the procedure for determining the pressure loads to be applied on a structure after an explosion is briefly described. The importance of the material model and its capability of including the high strain-rate effects in the numerical analysis is studied by comparing simulations by the FEM code EUROPLEXUS with published data of real blast experiments. These comparisons are made with respect t...

  14. Influence of Brick Walls on the Temperature Distribution in Steel Columns in Fire

    Directory of Open Access Journals (Sweden)

    António J. P. Moura Correia

    2009-01-01

    Full Text Available This paper reports on a study of steel columns embedded in walls in fire. Several fire resistance tests were carried out at the Laboratory of Testing Materials and Structures of the University of Coimbra, in Portugal. The temperatures registered in several points of the experimental models are compared with those obtained in numerical simulations carried out with the SUPERTEMPCALC finite element program. 

  15. The influence of Cr and Al pack cementation on low carbon steel to improve oxidation resistance

    Science.gov (United States)

    Prasetya, Didik; Sugiarti, Eni; Destyorini, Fredina; Thosin, Kemas Ahmad Zaini

    2012-06-01

    Pack chromizing and aluminizing has been widely used for many years to improve hot temperature oxidation and corrosion resistance of metals. The coating process involves packing the steel in a powder mixture which contain aluminum and chromium source, and inert filler (usually alumina), and halide activator NH4Cl. Al and Cr were deposited onto carbon steel by pack cementation process using elemental Al and Cr powder as Al and Cr source, whereas NiCo alloys codeposited by electrodeposition. The position of Al and Cr could be under or over Ni-Co alloys deposited. Pack cementation was heated on dry inert gas at temperature 800 °C about 5 hours and 20 minute for Cr and Al respectively. Al and Cr was successfully deposited. Laying down effect of Al and Cr onto carbon steel whether up and down toward NiCo alloys coating have affected to oxidation resistance. The pack aluminizing as top layer given best resitance to restrain excessive oxide scale, in contrast pack chromizing reveal bad oxidation resistance, moreover occured spallation on layer.

  16. Microstructure and creep properties of 9-12 % Cr-steels. The influence of Co

    Energy Technology Data Exchange (ETDEWEB)

    Kauffmann, F.; Zies, G.; Maile, K. [Stuttgart Univ. (Germany). MPA; Straub, S. [ALSTOM Power Systems, Mannheim (Germany); Mayer, K.H. [ALSTOM Power System, Nuernberg (Germany)

    2008-07-01

    The martensitic 9-12 wt. % Cr steels currently developed for the application in steam power plants are aimed for service temperatures above 600 C and steam pressures above 250 bar. The creep strength of these steels strongly depends on the microstructure and thereby on the chemical composition. In the present work, a combination of various microscopy techniques is used to study the microstructural changes of creep relevant features like subgrain-size, dislocation density, the chemical composition and crystallographic structure of the occurring precipitates as well as their density and size distribution in dependence of the addition of Co for several steels developed in the frame of the COST programs. These features are then correlated with the creep strength of the materials. The behavior of the alloy CB6 with a high Co content is compared to the low Co containing CB2 and the Co free B0 at 650 C. Similar comparisons are made for the alloy FN2, FN3 and FN 4 at 600 C. (orig.)

  17. The Influence of Surface Processing on Outgassing Measurements of High-Mn Stainless Steel

    Science.gov (United States)

    Fukaya, Masuhiro; Teraoka, Shin-Ichi; Sato, Yoshihiro; Uota, Masahiko; Saito, Yoshio

    An outgassing rate was measured for a stainless steel material of YUS130S, having a high-mangany content (Fe-18Cr-7Ni-11Mn-0.3N), and compared with that for a stainless steel of SUS304L. A surface processing of both electropolished and electrochemical buffing followed by an in-air oxidation was examined in order to investigate the outgas reduction effect in the case of with and without baking. Further, a depth profile of the surface composition was analyzed by glow-discharge emission spectroscopy (GDS). Based on the results, the outgassing rate of YUS130S was 35% lower than that of SUS304L, when electropolished and electrochemical buffing. The oxidation process in air at 723 K in the case of electrochemical buffing showed effect on the outgassing reduction in both YUS130S and SUS304L. The GDS observation shows that, by electropolishing, Cr-Mn-rich and Cr-rich passive films were formed on the YUS130S and SUS304L surface, respectively. By electrochemical buffing, passive films changed to more Fe-rich films. The further process of in-air-oxidation causes a change in oxide films to Fe-Mn-rich and Fe-rich characteristics for YUS130S and SUS304L respectively. The stainless steel with Mn-rich and Cr-poor passive films shows low outgassing rate.

  18. Influence of metal addition to BWR water on contamination and corrosion of stainless steel

    International Nuclear Information System (INIS)

    Oxide layers grown on stainless steel under modified BWR conditions with or without addition of different bivalent metal ions have been characterised using methods like SIMS and photo-electrochemistry. The Co-58 activity of the samples depends strongly on the thickness of the oxide film. Low pHT values generally favour dominance of p-type semiconductivity, implying a corrosion process controlled by cation transport through the oxide layer. High pHt values normally result in a change of semiconducting properties from predominantly p-type to n-type, which can be used as an indicator for a change in the corrosion mechanism. The metal ions added to high-temperature water do not significantly affect the specific activity of the different stainless steel samples after exposure. The aim of the described tests was to identify possible alternatives to zinc and to elucidate underlying mechanisms controlling the incorporation of radio-isotopes of cobalt in the oxide layer on stainless steel. Manganese has been identified in the described short-term exposure tests as a possible alternative to zinc. The positive effect of manganese must be confirmed by long-term tests. During these tests, the concentration of dissolved manganese should be reduced to 10 ppb maximum and the other water chemistry parameters should be also adjusted more closely to reactor coolant conditions. (orig./MM)

  19. The influence of Cr content on the mechanical properties of ODS ferritic steels

    Science.gov (United States)

    Li, Shaofu; Zhou, Zhangjian; Jang, Jinsung; Wang, Man; Hu, Helong; Sun, Hongying; Zou, Lei; Zhang, Guangming; Zhang, Liwei

    2014-12-01

    The present investigation aimed at researching the mechanical properties of the oxide dispersion strengthened (ODS) ferritic steels with different Cr content, which were fabricated through a consolidation of mechanical alloyed (MA) powders of 0.35 wt.% nano Y2O3 dispersed Fe-12.0Cr-0.5Ti-1.0W (alloy A), Fe-16.0Cr-0.5Ti-1.0W (alloy B), and Fe-18.0Cr-0.5Ti-1.0W (alloy C) alloys (all in wt.%) by hot isostatic pressing (HIP) with 100 MPa pressure at 1150 °C for 3 h. The mechanical properties, including the tensile strength, hardness, and impact fracture toughness were tested by universal testers, while Young's modulus was determined by ultrasonic wave non-destructive tester. It was found that the relationship between Cr content and the strength of ODS ferritic steels was not a proportional relationship. However, too high a Cr content will cause the precipitation of Cr-enriched segregation phase, which is detrimental to the ductility of ODS ferritic steels.

  20. Influence of Mo addition on the tempered properties of 13Cr martensitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Byong Ho; Ahn, Yong Sik [Pukyong National Univ., Busan (Korea, Republic of)

    1998-11-01

    In order to investigate the effect of Mo addition on the mechanical properties of 13Cr-0.2C martensitic stainless steel, tensile test and Charpy V-notch test were performed after tempering at the temperature range of 200{approx}700 .deg. C following austenitizing at 1100 .deg. C. The yield strength and hardness of the steel were increased with the increase of Mo content at all tempering conditions, because Mo causes retardation of precipitation and coarsening of carbides and solid solution strengthening of matrix. Except 500 .deg. C of tempering temperature, the Charpy impact energy was significantly increased with Mo content and showed the highest value at 1.5 wt% addition. The increase of impact energy of the steel containing Mo is thought to be caused by {delta}-ferrite formed in the tempered martensitic matrix. At 500 .deg. C tempering, Charpy impact energy was decreased drastically due to temper embrittlement and it was not possible to prevent it even though Mo was added up to 1.5 wt%.

  1. INFLUENCE OF SHOCK VOLTAGE FROM THE ELECTRIC DISCHARGE ON THE FATIGUE ENDURANCE OF CARBON STEEL IN WATER

    Directory of Open Access Journals (Sweden)

    I. O. Vakulenko

    2015-09-01

    Full Text Available Purpose. The research supposes the explanation of influence of stress impulses from an electrical discharge in water on the level of the limited endurance at a cyclic loading of the thermally work-hardened carbon steel. Methodology. Material for research was steel 45 (0,45 % carbon with сoncentration of chemical elements within the limits of steel composition. Specimens for tests are made as plates in 1 thick, width 15 and length 120-180 mm. The structural state of steel corresponded to quenching on a martensite from the normal temperatures of annealing and tempering at 300C, duration of 1 h. Microstructure was investigated with the use of electronic microscopy, the density of dislocations was estimated on the methods of X-ray analysis. Hardness was measured on the method of Rockwell (scale of «C». A cyclic loading was carried out in the conditions of symmetric bend on a tester «Saturn-10» at a temperature +20C. The treatment by shock voltage from the electrical discharge was carried out in water on setting of bath type «Iskra-23», used for cleaning of castings manufactures. Electric impulses were formed at 15-18 kV with energy of 10-12 kJ and amplitude of 1-2 GPа. Findings. As a result of processing pulses of a pressure wave of heat-strengthened steel 45 found the increase of endurance under the cyclic loading corresponds to an increased amount of accumulated dislocations on the fracture surface. The use of Coffin–Manson Equation allowed finding the decrease of deformation per cycle of loading as a result of arising stress from an electrical discharge in water. On the fracture surface (after pulse exposure was found the increased number of dislocations, located in different crystallographic systems, that is a testament to the rather complicated development of dislocation transformations in the structure of steel, which provide an increase of endurance at a fatigue. The increase of the limited endurance became as a result of impulsive

  2. A Study of the Influence of Thermomechanical Controlled Processing on the Microstructure of Bainite in High Strength Plate Steel

    Science.gov (United States)

    Liang, Xiaojun; DeArdo, Anthony J.

    2014-10-01

    , equiaxed austenite to deformed, pancaked austenite, which were followed by seven different cooling rates ranging between 0.5 K/s (0.5 °C/s) and 40 K/s (40 °C/s). The CCT curves showed that the transformation behaviors and temperatures varied with starting austenite microstructure and cooling rate, resulting in different final microstructures. The EBSD results and the thermodynamics and kinetics analyses show that in low carbon bainite, the nucleation rate is the key factor that affects the bainitic ferrite morphology, size, and orientation. However, the growth of bainite is also quite important since the bainitic ferrite laths apparently can coalesce or coarsen into larger units with slower cooling rates or longer isothermal holding time, causing a deterioration in toughness. This paper reviews the formation of bainite in this steel and describes and rationalizes the final microstructures observed, both in terms of not only formation but also for the expected influence on mechanical properties.

  3. Intergranular brittle fracture of a low alloy steel induced by grain boundary segregation of impurities: influence of the microstructure

    International Nuclear Information System (INIS)

    The study contributes to improve the comprehension of intergranular embrittlement induced by the phosphorus segregation along prior austenitic grain boundaries of low alloy steels used in pressurized power reactor vessel. A part of this study was performed using a A533 steel which contains chemical fluctuations (ghost lines) with two intensities. Axi-symmetrically notched specimens were tested and intergranular brittle de-cohesions were observed in the ghost lines. The fracture initiation sites observed on fracture surfaces were identified as MnS inclusions. A bimodal statistic obtained in a probabilistic model of the fracture is explained by the double population of ghost lines' intensities. A metallurgical study was performed on the same class of steel by studying the influence of the microstructure on the susceptibility to temper embrittlement. Brittle fracture properties of such microstructures obtained by dilatometric experiments were tested on sub-sized specimens to measure the V-notched fracture toughness. Fraction areas of brittle fracture modes were determined on surface fractures. A transition of the fracture mode with the microstructure is observed. It is shown that tempered microstructures of martensite and lower bainite are more susceptible to intergranular embrittlement than tempered upper bainitic microstructure. The intergranular fracture is the most brittle mode. The analysis of crystalline mis-orientations shows a grain boundary structure appreciably more coherent for tempered microstructures of martensite and lower bainite. The higher density of random grain boundaries is susceptible to drag the phosphorus in the upper bainitic matrix and to make the quantity of free phosphorus decreasing. Microstructure observations show a difference in the size and the spatial distribution of carbides, essentially cementite, between tempered martensite and upper bainite. It can explain the bigger susceptibility of this last microstructure to cleavage mode

  4. Influence of heat treatment on the Al-Si coating adhesion to steel strips

    OpenAIRE

    K. Żaba

    2010-01-01

    A division of methods of coatings adhesion investigations, with special emphasis on qualitative methods is presented in the paper. Theobtained results the Al-Si coating adhesion to a steel strips of DX52D grade are given. This strip was examined before and after the heattreatment in temperatures 250-700oC during 30-1440 minutes. Methods of thermal shock, bending, filing, network of cuts and tensile wereapplied in examinations. The assessment of the method adequacy was performed. Structure cha...

  5. Influence of heat treatment on mechanical properties of 300M Steel

    Science.gov (United States)

    Youngblood, J. L.; Raghavan, M. R.

    1975-01-01

    The plane strain fracture toughness and tensile strength response of 300M Steel to a wide variety of austenitizing and tempering temperatures were investigated. The results make it possible for one to select heat treatments which provide an optimum combination of strength and toughness for a variety of structural applications. In particular, improvements in toughness on the order of 20% were found possible with no loss in tensile properties by increasing the austenitizing temperature from the currently employed 1144 K to 1255 K or higher, and this change in heat treatment therefore appears worthy of general implementation.

  6. Influence of Carbon Content on Fatigue Strength of Drawn Steel Tubes for Small Once-Through Boiler

    Science.gov (United States)

    Yonekura, Daisuke; Fujie, Yuta; Murakami, Ri-Ichi; Tokunaga, Yukihiro

    Tension-tension fatigue tests were performed to examine the influence of carbon content on the fatigue properties of drawn specific steel tube (STB340) with/without post heat treatment for small once-through boiler. Two different carbon content steel tubes, C=0.06 and 0.12% were prepared. The as-received, as-drawn and post drawing heat treated series for each carbon content tube were prepared for fatigue test. The hardness, grain size and residual stress were measured for each series. As a result, the fatigue strength of as-received and as-drawn series showed a small difference between C=0.06 and 0.12% specimens. However, the post drawing heat treatment series showed obvious difference in the fatigue strength. The fatigue strength of higher carbon content tubes significantly decreased by the post drawing heat treatment, whereas the decrease of fatigue strength was little for lower carbon content heat treated tubes. The difference of fatigue strength was mainly caused by the degree of relaxation of work hardening by post heat treatment.

  7. Influence of the static strain ageing on the ductile-to-brittle transition in C-Mn steel

    International Nuclear Information System (INIS)

    Ferritic steels for industrial structures have a brittle-ductile transition toughness and impact energy with temperature. Their resistance to the brittle fracture plays an essential role in the safety certification of industrial structures. Nowadays, the performance and the durability are key issues for major players such as EDF. In these approaches ductile-to-brittle transition toughness and impact energy, toughness is predicted from resilience. Several previous studies have shown that the probability of cleavage fracture can be adequately described in brittle plateau by a local approach to fracture. However, these studies assume that the material does not undergo strain aging, which is rarely relevant for low carbon steels and low calmed down. The work consisted firstly to characterize the behavior and secondly to propose a robust and explicit modeling of the observed phenomena. Characterization consisted of performing tensile tests between -150 C and 20 C for several strain rates. A model able to simulate the static aging is identified by implementing an appropriate and systematic strategy. Impact resistance test allows us to build the curve of ductile-to-brittle transition of the material for different conditions to understand and observe the influence of static strain aging on the failure. Finally, the modeling of the brittle fracture has been described for all experimental conditions tested using the model developed and identified in the previous section to predict the transition for different material conditions. (author)

  8. Deformability analysis of the AISI 304 DDQ stainless steel under deep drawing multiaxial condition. Evaluation of the initial strain influence

    International Nuclear Information System (INIS)

    The deep drawing formability of a material is established as a function of standard indexes, as strength coefficient and anisotropy coefficient. But these indexes are determined in different conditions to those that take place in the forming process. The simulative assays do not separate the actions due to the different variables that work in the process, as for example, the rolling direction. In the present work a test that uses a wedge shape die is considered in order to obtain the strength and anisotropy coefficients as a function of rolling direction. This way, the assays are carried out under a tensile-biaxial compression stress state similar to that one taking place in the flange zone in deep drawing. The experimented material is a deep drawing quality stainless steel AISI 304. The influence of initial strengthened states, rolling and uniaxial tensile on the steel behaviour are also studied. The results permits the authors establish the validity of the assay from the point of view of the strains produced in the sheet. The initial strain has a higher effect on the material than that one obtained from the tensile-biaxial of the state than the tensile-biaxial compression causes. The anisotropy coefficient changes with the strain for the sheet rolling direction. (Author).

  9. Influence of microstructure on stress corrosion cracking of mild steel in synthetic caustic-nitrate nuclear waste solution

    International Nuclear Information System (INIS)

    The influence of alloy microstructure on stress corrosion cracking of mild steel in caustic-nitrate synthetic nuclear waste solutions was studied. An evaluation was made of the effect of heat treatment on a representative material (ASTM A 516 Grade 70) used in the construction of high activity radioactive waste storage tanks at Savannah River Plant. Several different microstructures were tested for susceptibility to stress corrosion cracking. Precracked fracture specimens loaded in either constant load or constant crack opening displacement were exposed to a variety of caustic-nitrate and nitrate solutions. Results were correlated with the mechanical and corrosion properties of the microstructures. Crack velocity and crack arrest stress intensity were found to be related to the yield strength of the steel microstructures. Fractographic evidence indicated pH depletion and corrosive crack tip chemistry conditions even in highly caustic solutions. Experimental results were compatible with crack growth by a strain-assisted anodic dissolution mechanism; however, hydrogen embrittlement also was considered possible

  10. Dynamic study of passive layers formed on stainless steels in chloride environment. Correlation with stress corrosion behaviour - influence of some alloying elements

    International Nuclear Information System (INIS)

    This research thesis reports the study of the nature and stability of passive films formed on stainless steels in chloride solutions in order to predict the conditions under which some forms of localized corrosion may occur. It aims at understanding the influence of surface preparation, of temperature, of strain rate, and, above all, of alloying elements on the reconstruction kinetics of the passive film after a disturbance induced by a mechanical action. After a discussion of the various techniques used to study passive films, and of their results, the author presents the experimental method (potentiostatic test and mechanical de-passivation test) and the obtained results which are then interpreted, more particularly in terms of influence of alloying elements (nickel, molybdenum, copper, titanium, austeno-ferritic steel). Correlations are established between the dynamic behaviour of passive films formed on the studied steels, and their sensitivity to stress corrosion cracking

  11. Influence of metastable retained austenite on macro and micromechanical properties of steel processed by the Q and P process

    Energy Technology Data Exchange (ETDEWEB)

    Jirková, Hana, E-mail: h.jirkova@email.cz [University of West Bohemia, Research Centre of Forming Technology – FORTECH, Univerzitni 22, 306 14 Pilsen (Czech Republic); Mašek, Bohuslav [University of West Bohemia, Research Centre of Forming Technology – FORTECH, Univerzitni 22, 306 14 Pilsen (Czech Republic); Wagner, Martin F.-X. [Chemnitz University of Technology, Materials Engineering Group, Erfenschlager Str. 73, 09125 Chemnitz (Germany); Langmajerová, Danuše; Kučerová, Ludmila [University of West Bohemia, Research Centre of Forming Technology – FORTECH, Univerzitni 22, 306 14 Pilsen (Czech Republic); Treml, Ruth; Kiener, Daniel [Montanuniversität Leoben, Department Materials Physics, Jahnstrasse 12/I, 8700 Leoben (Austria)

    2014-12-05

    Highlights: • New methods of heat treatment were applied at low alloyed high strength steel. • High UTS of 1907 MPa with ductility of 17% were obtained for low alloyed steel. • Test of deformation behavior of martensite–austenite microstructure in micro-volumes. • Plastic deformation higher than 17% was obtained for martensite microstructure RA. - Abstract: By stabilising metastable austenite with a suitable morphology in a martensitic structure, it is possible to impart to multi-phase steels high ductility combined with tensile strengths exceeding 2000 MPa. One way to achieve such mixed structures consisting of martensite and retained austenite (RA) is the Q and P (quenching and partitioning) process. The resulting structure contains metastable austenite in the form of thin foils located between martensite laths or plates. The stability of austenite under mechanical loading is the essential factor contributing to the extraordinary plasticity of such materials during cold deformation. A steel with 0.43% of carbon, alloyed with manganese, silicon and chromium was chosen for the experiment described in the present paper. Using the Q and P process, a martensitic structure with 20% of retained austenite was obtained. As cold plastic deformation causes the austenite to transform, 10% cold deformation was applied after the Q and P process. This deformation reduced the RA fraction to 11%. Materials prepared by this method were examined using micro-pillar compression experiments. Using the focused ion beam (FIB) method, pillars of 3 × 3 μm cross-section and 8 μm length were fabricated. These were afterwards mechanically tested in situ in an electron microscope in quasi-static compression at a true strain rate of 3 × 10{sup −4} s{sup −1} to different amounts of plastic strain. The experiment showed that mechanical properties of the two conditions of material differ in terms of yield strength and the strain hardening exponent. An additional metallographic

  12. Influence of technetium on the microstructure of a stainless steel-zirconium alloy

    International Nuclear Information System (INIS)

    Stainless steel-zirconium alloys are being developed for the disposal of metallic waste generated during the electrometallurgical treatment of spent Experimental Breeder Reactor (EBR-II) fuel. The metallic waste contains the fission product technetium, which must be incorporated into a stable waste form matrix to prevent its release into the environment. The baseline waste form for metallic waste from EBR-II fuels is a stainless steel-15 wt% zirconium (SS-15Zr) alloy. The microstructure of SS-15Zr alloys containing 2 wt% technetium was characterized using a combination of microscopy, spectroscopy, diffraction, and chemical analysis techniques. Peaks corresponding to the iron solid solutions ferrite and austenite, ZrFe2-type Laves polytypes C36 and C15, and an Fe23Zr6-type intermetallic were identified in diffraction patterns of the alloy. Discrete technetium-rich phases were not observed either in diffraction patterns or in the microstructure; the element partitioned into various phases of the SS-15Zr alloy. Technetium favors ferrite and austenite over the Zr-based intermetallics. The lattice parameters of the Zr-based intermetallics are smaller than those in an alloy without technetium, which appears to substitute at the zirconium sites of the intermetallic lattice

  13. Influence of High Strength Steel Microstructure on Fatigue Crack Growth Rate

    Directory of Open Access Journals (Sweden)

    Enefola S. Ameh

    2016-07-01

    Full Text Available This study examines the effect of high strength steel microstructure morphology on fatigue crack growth rate (FCGR. To achieve this aim, three different heat treatment methods (normalizing, austempering quenching and tempering were considered and all the steel specimens were initially heated to 9500C austenization temperature for ninety minutes and then processed via the different heat treatment methods before viewing the resultant microstructures under light optical microscope (LOM. Fatigue crack growth rate tests were conducted on the resultant microstructures with compact tension specimens at room temperature as prescribed by American standard testing method E647. Results of FCGR tests showed normalized microstructure has the lowest FCGR (6.2698E-06, followed by quenched and tempered (7.9519E-06, asreceived (8.15E-06 and austempered (9.6667E-06 microstructure considering a low stress intensity factor range. The trend of results showed insignificant effect of microstructure over the Paris regime growth indicating fatigue crack growth rate is not a reliable parameter for correlating rate of crack propagation to microstructure

  14. Influence of fluence rate on radiation-induced mechanical property changes in reactor pressure vessel steels

    Energy Technology Data Exchange (ETDEWEB)

    Hawthorne, J.R.; Hiser, A.L. (Materials Engineering Associates, Inc., Lanham, MD (USA))

    1990-03-01

    This report describes a set of experiments undertaken using a 2 MW test reactor, the UBR, to qualify the significance of fluence rate to the extent of embrittlement produced in reactor pressure vessel steels at their service temperature. The test materials included two reference plates (A 302-B, A 533-B steel) and two submerged arc weld deposits (Linde 80, Linde 0091 welding fluxes). Charpy-V (C{sub v}), tension and 0.5T-CT compact specimens were employed for notch ductility, strength and fracture toughness (J-R curve) determinations, respectively. Target fluence rates were 8 {times} 10{sup 10}, 6 {times} 10{sup 11} and 9 {times} 10{sup 12} n/cm{sup 2} {minus}s{sup {minus}1}. Specimen fluences ranged from 0.5 to 3.8 {times} 10{sup 19} n/cm{sup 2}, E > 1 MeV. The data describe a fluence-rate effect which may extend to power reactor surveillance as well as test reactor facilities now in use. The dependence of embrittlement sensitivity on fluence rate appears to differ for plate and weld deposit materials. Relatively good agreement in fluence-rate effects definition was observed among the three test methods. 52 figs., 4 tabs.

  15. Influence of PWHT on Toughness of High Chromium and Nickel Containing Martensitic Stainless Steel Weld Metals

    Science.gov (United States)

    Divya, M.; Das, Chitta Ranjan; Mahadevan, S.; Albert, S. K.; Pandian, R.; Kar, Sujoy Kumar; Bhaduri, A. K.; Jayakumar, T.

    2015-06-01

    Commonly used 12.5Cr-5Ni consumable specified for welding of martensitic stainless steels is compared with newly designed 14.5Cr-5Ni consumable in terms of their suitability for repair welding of 410 and 414 stainless steels by gas tungsten arc welding process. Changes in microstructure and austenite evolution were investigated using optical, scanning electron microscopy, X-ray diffraction techniques and Thermo-Calc studies. Microstructure of as-welded 12.5Cr-5Ni weld metal revealed only lath martensite, whereas as-welded 14.5Cr-5Ni weld metal revealed delta-ferrite, retained austenite, and lath martensite. Toughness value of as-welded 12.5Cr-5Ni weld metal is found to be significantly higher (216 J) than that of the 14.5Cr-5Ni weld metal (15 J). The welds were subjected to different PWHTs: one at 923 K (650 °C) for 1, 2, 4 hours (single-stage PWHT) and another one at 923 K (650 °C)/4 h followed by 873 K (600 °C)/2 h or 873 K (600 °C)/4 h (two-stage heat treatment). Hardness and impact toughness of the weld metals were measured for these weld metals and correlated with the microstructure. The study demonstrates the importance of avoiding formation of delta-ferrite in the weld metal.

  16. Influence of combined thermomechanical treatment on impurity segregation in ferritic-martensitic and austenitic stainless steels

    Science.gov (United States)

    Ilyin, A. M.; Neustroev, V. S.; Shamardin, V. K.; Shestakov, V. P.; Tazhibaeva, I. L.; Krivchenkoa, V. A.

    2000-12-01

    In this study 13Cr2MoVNb ferritic-martensitic steel (FMS) and 16Cr15Ni3MoNb austenitic stainless steel (ASS) tensile specimens were subjected to standard heat treatments and divided into two groups. Specimens in group 1 (FMS only) were aged at 400°C in a stress free and in an elastically stressed state with a tensile load (100 MPa) then doped with hydrogen in an electrolytic cell. Specimens in group 2 were subjected to cold work (up to 10%) and exposed to short-time heating at 500° for 0.5 h. All specimens were fractured at room temperature in an Auger spectrometer and Auger analysis of the fracture surfaces was performed in situ after fracturing. A noticeable increase of N and P segregation levels and a widening of the depth distribution on the grain boundary facets were observed in the FMS after aging in the stressed state. Cold-worked FMS and ASS showed a ductile dimple mode of fracture, but relatively high levels of S, P and N were observed on the dimple surfaces. We consider the origin of such effects in terms of the stressed state and plastic-deformation-enhanced segregation.

  17. Influence of defect states on band gaps in the two-dimensional phononic crystal of 4340 steel in an epoxy

    Institute of Scientific and Technical Information of China (English)

    Kong Xiao-Yan; Yue Lei-Lei; Chen Yu; Liu Ying-Kai

    2012-01-01

    The band structures of a new two-dimensional triangle-shaped array geometry of 4340 steel cylinders of square cross section in an epoxy resin were studied by the plane-wave expansion and supercell calculation method.The band gaps of this type of phononic crystals with different defects were calculated such as defect-free,60° crystal linear defect states,120° crystal linear defect states,and 180° crystal linear defect states.It was found that the band gap will emerge in different linear defects of the phononic crystals and the bandwidth of linear defect states is larger than that of the free-defect crystal by about 2.14 times within the filling fraction F = 0.1-0.85.In addition,the influence of the filling fraction on the relative width of the minimum band gap is discussed.

  18. Influence of the finish rolling temperatures on the microstructure and texture evolution in the ferritic stainless steels

    Institute of Scientific and Technical Information of China (English)

    Fei GAO; Zhen yu LIU; Haitao LIU; Guodong WANG

    2011-01-01

    The influence of the finish rolling temperature on the microstructure and texture evolution of Nb and B micro-alloyed ultra purified Cr17 ferritic stainless steels was investigated.The hot rolled bands were produced by conventional rolling process and the finish rolling at relatively low temperatures or “warm rolling”.The microstructure was observed by optical microscopy,scanning electron microscopy and transmission electron microscopy,and X-ray diffraction was used to characterize the texture evolution processes.The results showed that as compared to conventional hot rolling process,the warm rolling has led to the refined and homogeneous microstruc ture and uniform recrystallization texture along γ-fiber in final sheets,indicating that the finish rolling at relatively low temperatures can be the effective way to improve significantly the formability of final sheets.

  19. Mechanosynthesis of zinc ferrite in hardened steel vials: Influence of ZnO on the appearance of Fe(II)

    International Nuclear Information System (INIS)

    Nanocrystalline ZnFe2O4 spinel powders are synthesized by high-energy ball milling, starting from a powder mixture of hematite (α-Fe2O3) and zincite (ZnO). The millings are performed under air using hardened steel vials and balls. X-ray diffraction and Moessbauer spectrometry are used to characterize the powders. A spinel phase begins to appear after 3 h of milling and the synthesis is achieved after 9 h. Phase transformation is accompanied by a contamination due to iron coming from the milling tools. A redox reaction is also observed between Fe(III) and metallic iron during milling, leading to a spinel phase containing some Fe(II). The mechanism for the appearance of this phase is studied: ZnO seems to have a non-negligeable influence on the synthesis, by creating an intermediate wuestite-type phase solid solution with FeO

  20. Factors influencing the growth of cracks from defects in CDFR specification 316 stainless steel thermal shock specimens

    International Nuclear Information System (INIS)

    The growth of cracks from spark machined slits and gouged grooves has been studied in a CDFR specification cast of 316 stainless steel under thermal shock conditions using sodium as the heat transfer medium. Comparative uniaxial creep fatigue tests have also been performed in servohydraulic machines under isothermal conditions. The cycles used for the thermal shock tests consisted of step increases in temperatures of between 75 and 300 C followed by tensile holds at 600 C of duration 0.05 to 24 hours, and finally slow cooling to the initial temperature ready for the next cycle. The results are presented showing the influence on crack growth of strain range, hold time, number of cycles, types of defect and ferrite stringer direction. (author)

  1. The influence of low oxygen and contaminated sodium environments on the fatigue behaviour of solution treated AISI 316 stainless steel

    International Nuclear Information System (INIS)

    The influence of air and sodium environments on the fatigue properties of solution treated AISI 316 steel was studied by predictive methods and by conducting tests in air, in high temperature sodium, or following pre-exposure to sodium. The sodium environments studied included contaminated sodium or the products of sodium/water flames possibly typical of fast water reactor fault conditions, and low oxygen sodium more appropriate to normal plant operation. Generally, fatigue properties were reduced by contaminated sodium or the products of sodium/water flames and improved by low oxygen sodium when compared with similar tests conducted in air. However, complex effects were observed with respect to crack initiation. The experimental results are discussed and generally follow trends predicted by physically based fatigue models. (author)

  2. Influence of additives on electrodeposition of bright Zn–Ni alloy on mild steel from acid sulphate bath

    Indian Academy of Sciences (India)

    S Shivakumara; U Manohar; Y Arthoba Naik; T V Venkatesha

    2007-10-01

    The influence of a condensation product (CP) of veratraldehyde (VRTD) and -amino benzoic acid (PABA) on Zn–Ni alloy electrodeposited onto mild steel was studied in acidic sulphate solutions. Ethylenediaminetetraaceticacid (EDTA) and cetyltrimethylammoniumbromide (CTAB) were used as complexing and wetting agents, respectively. The effect of bath constituents, pH, current density and temperature on nature of deposit were studied through Hull cell experiments. The bath constituents and operating parameters were optimized. Deposit properties and corrosion resistance were discussed. Throwing power, current efficiency and polarization studies were carried out. SEM photomicrographs of the deposit obtained from optimum bath revealed fine-grained deposit of the alloy in the presence of condensation product and hence modified the morphology of zinc–nickel alloy deposit. IR spectrum of the scrapped deposit showed inclusion of addition agent.

  3. Influence of heat treatment on microstructure and properties of GX12CrMoVNbN9-1 cast steel

    Directory of Open Access Journals (Sweden)

    G. Golański

    2010-07-01

    Full Text Available The paper presents results of research on the influence of multistage heat treatment on microstructure and properties of high-chromiummartensitic GX12CrMoVNbN9 – 1 (GP91 steel. The material under investigation were samples taken out from a test coupon. Heattreatment of GP91 cast steel was performed at the parameters of temperature and time typical of treatment for multi-ton steel casts. The research has proved that in the as-received condition (as-cast state GP91 cast steel was characterized by a coarse grain, martensitic microstructure which provided the required standard mechanical properties. The heat treatment of GP91 cast steel contributed to obtainment of a fine grain microstructure of high tempered martensite with numerous precipitations of carbides of diverse size. The GP91 cast steel structure received through heat treatment made it possible to obtain high plastic properties, particularly impact strength, maintaining strength properties on the level of the required minimum.

  4. Criterion of cleavage crack propagation and arrest in a nuclear PWR vessel steel

    International Nuclear Information System (INIS)

    The purpose of this PhD thesis is to understand physical mechanisms of cleavage crack propagation and arrest in the 16MND5 PWR vessel steel and to propose a robust predicting model based on a brittle fracture experimental campaign of finely instrumented laboratory specimens associated with numerical computations. First, experiments were carried out on thin CT25 specimens at five temperatures (-150 C, -125 C, -100 C, -7 C, -50 C). Two kinds of crack path, straight or branching path, have been observed. To characterize crack propagation and to measure crack speed, a high-speed framing camera system was used, combined with the development of an experimental protocol which allowed to observe CT surface without icing inside the thermal chamber and on the specimen. The framing camera (520 000 fps) has allowed to have a very accurate estimation of crack speed on the complete ligament of CT (∼ 25 mm). Besides, to analyse experiments and to study the impact of viscosity on the mechanical response around the crack tip, the elastic-viscoplastic behavior of the ferritic steel has been studied up to a strain rate of 104 s-1 for the tested temperatures.The extended Finite Element Method (X-FEM) was used in CAST3M FE software to model crack propagation. Numerical computations combine a local non linear dynamic approach with a RKR type fracture stress criterion to a characteristic distance. The work carried out has confirmed the form of the criterion proposed by Prabel at -125 C, and has identified the dependencies of the criterion on temperature and strain rate. From numerical analyzes in 2D and 3D, a multi-temperature fracture stress criterion, increasing function of the strain rate, was proposed. Predictive modeling were used to confirm the identified criterion on two specimen geometries (CT and compressive ring) in mode I at different temperatures. SEM observations and 3D analyzes made with optical microscope showed that the fracture mechanism was the cleavage associated

  5. Influence of Steel Slag Fineness and Mixture Amount on Composite Cement Containing Steel Slag Powders%钢渣细度和掺量对钢渣复合水泥力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    赵鸿

    2012-01-01

    为找出在钢渣复合水泥中钢渣的最佳细度和最佳掺量,从钢渣的粉磨时间、掺量、不同助磨剂的作用和水泥配比等方面研究钢渣细度及掺量对复合水泥力学性能的影响,分析各个影响因素的作用.结果表明,随着磨细钢渣粒度的减小,钢渣复合水泥的抗折、抗压强度会有不同程度的提高;磨细钢渣的掺量为10%和20%时,钢渣复合水泥的力学性能较好,抗折、抗压强度甚至超过纯水泥;当掺量为30%和40%时,复合水泥力学强度下降幅度较大,3d抗折强度不符合国家标准规定.%In order to get the optimal steel slag fineness and the best mixture amount of steel slag powders in the composite cement containing steel slag, the influence of fineness and mixture amount of steel slag powders on the mechanical property of composite cement were studied based on the grinding time of steel slag, mixture amount, application of different grinding agent and proportion of cement and ground steel slag powders. The effect of each factor was analyzed. The results show that the flexible strength and compressive strength of composite cement increase to some extent with the decrease of particle size of ground steel slag. When the mass fraction of ground steel slag powders in composite cement is 10% and 20%, the mechanical property of the composite cement improve, its flexible strength and compressive strength exceed the pure cement. When the mass fraction of ground steel slag powders is 30% and 40% , the mechanical strength of the composite cement decrease obviously, 3 d flexible strength does not meet the requirements of the national standard.

  6. Modelling Cr depletion under a growing Cr2O3 layer on austenitic stainless steel: the influence of grain boundary diffusion

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Hattel, Jesper Henri; Dahl, Kristian Vinter;

    2009-01-01

    The oxidation behaviour of austenitic stainless steels in the temperature range 723–1173K is strongly influenced by the grain size of the oxidizing alloy. In this work the evolution of the concentration profiles of Cr, Ni and Fe in the substrate below a growing Cr2O3 layer is simulated...

  7. The quenching influence on defect structure and far acting stress fields of the 30CrNi3MoVA steel

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ The determination of the quenching influence on defect structure and far acting stress fields of the cast constructional steel 30CrNi3MoVA (0.3%C, 1%Cr, 3%Ni, 1%Mo, 1%V) was the purpose of this work.

  8. The quenching influence on defect structure and far acting stress fields of the 30CrNi3MoVA steel

    Institute of Scientific and Technical Information of China (English)

    Kozlov; E.; V.; Popova; N.; A.; Klimashin; S.; I.; Tsellermaer; V.V.; Konovalov; S.; V.; Gromov; V.; E.

    2005-01-01

    The determination of the quenching influence on defect structure and far acting stress fields of the cast constructional steel 30CrNi3MoVA (0.3%C, 1%Cr, 3%Ni, 1%Mo, 1%V) was the purpose of this work.……

  9. The influence of pluronic P123 micelles on corrosion behaviour of steel in cement extract and bulk matrix properties of cement paste

    NARCIS (Netherlands)

    Koleva, D.A.; Denkova, A. .G.; Hu, J.; van Breugel, K.

    2012-01-01

    The influence of Pluronic P123 (PEO20-PPO20-PEO70) micelles (of 10 nm size) on the corrosion behaviour of low carbon steel in cement extract (CE) was studied using electrochemical impedance spectroscopy (EIS) and potentio-dynamic polarisation (PDP). Additionally, mercury intrusion porosimetry (MIP)

  10. Influence of alumina and titanium dioxide coatings on abrasive wear resistance of AISI 1045 steel

    Science.gov (United States)

    Santos, A.; Remolina, A.; Marulanda, J.

    2016-02-01

    This project aims to compare the behaviour of an AISI 1045 steel's abrasive wear resistance when is covered with aluminium oxide (Al2O3) or Titanium dioxide (TiO2), of nanometric size, using the technique of thermal hot spray, which allows to directly project the suspension particles on the used substrate. The tests are performed based on the ASTM G65-04 standard (Standard Test Method for Measuring Abrasion Using the Dry Sand/Rubber Apparatus). The results show that the amount of, lost material increases linearly with the travelled distance; also determined that the thermal treatment of hardening-tempering and the alumina and titanium dioxide coatings decrease in average a 12.9, 39.6 and 29.3% respectively the volume of released material during abrasive wear test.

  11. Influence of cryogenic treatment on the wear characteristics of 100Cr6 bearing steel

    Institute of Scientific and Technical Information of China (English)

    R Sri Siva; D Mohan Lal; P Kesavan Nair; M Arockia Jaswin

    2014-01-01

    A series of reciprocating wear tests were performed on the deep cryogenically treated and conventionally heat-treated samples of 100Cr6 bearing steel to study the wear resistance. The worn surfaces as well as the wear debris were analyzed by scanning electron micros-copy. The improvement in wear resistance of the deep cryogenically treated samples ranges from 49%to 52%. This significant improvement in wear resistance can be attributed to finer carbide precipitation in the tempered martensitic matrix and the transformation of retained aus-tenite into martensite. X-ray diffraction analysis shows that the volume fraction of retained austenite in the conventionally heat-treated sam-ples is 14%and that of the deep cryogenically treated samples is only 3%.

  12. The Influence of Method of Carburizing and Nitrocarburizing on the Microstructure and Properties of Tool Steels

    Institute of Scientific and Technical Information of China (English)

    Tomasz Babul; Natalia Kucharieva; Aleksander Nakonieczny; Jan Senatorski

    2004-01-01

    The paper presents the results of wear and metallography tests of tool steel grades: ASTM A681, Chl2M and Ch12FS per GOST, AMS 6437E i BS X46Cr13, all surface hardened by the Carbo process (carburizing) and by the NiCar process (nitrocarburizing). The thermo-chemical treatment was conducted in powder pack for a duration of 6 h (carburizing)and for 4 h in the case of nitrocarburizing. Factors investigated were: morphology, depth and microhardness of the cases obtained, their microstructure, as well as phase composition. Wear tests were conducted by the three cylinder-cone method.Wear velocity was 0.58 m/s, unit load was 50 MPa and 400Mpa, wear path was 3470 m. Oil SAE30 was applied at the rate of 30 drops per minute.

  13. Influence of weld structure on cross-weld creep behavior in P23 steel

    Energy Technology Data Exchange (ETDEWEB)

    Allen, D.J.; Degnan, C.C. [E.ON Engineering (United Kingdom); Brett, S.J. [RWE npower (United Kingdom); Buchanan, L.W. [Doosan Babcock (United Kingdom)

    2010-07-01

    A thick section pipe weld in low alloy steel P23 has been characterised by cross-weld creep rupture testing at a range of stresses, together with all-weld-metal and parent material testing, under the auspices of the UK High Temperature Power Plant Forum. The results generally show that the weld metal can be weak when tested in the transverse (cross-weld) orientation, and can fail with limited overall ductility by cracking in the zone of refined weld metal beneath the fusion boundary of the superposed weld bead. However, one specimen showed a much superior performance, which could be understood in terms of its locally more creep resistant weld macrostructure. The implications for P23 performance and weld manufacture are discussed. (orig.)

  14. Phase transformation and cooling curves of the mild steel influenced by previous hot rolling

    Directory of Open Access Journals (Sweden)

    S. Rusz

    2016-10-01

    Full Text Available Rods from mild steel S235JR were intensively rolled in the laboratory continuous mill. Specifically defined temperature of phase transformation Ar was determined from the free cooling curves measured by the temperature scanner. The Ar value increased from 763 to 786 °C with rolling temperature descending from 1 200 to 800 °C. The value of Ar = 730 °C was obtained at free cooling of the non-deformed rod of the same diameter 9,8 mm from heating temperature 1 000 °C. The obtained results were compared with continuous cooling transformation (CCT and deformation continuous cooling transformation (DCCT diagrams based on the dilatometric tests.

  15. Influence of thermal aging on the reactivity of duplex stainless steel surfaces

    Science.gov (United States)

    Amadou, T.; Rhouma, A. Ben; Sidhom, H.; Braham, C.; Ledion, J.

    2000-08-01

    The annealing of large cast pieces in duplex stainless steel (SS) and the different heat cycles resulting from repairs involve significant structural changes characterized by carbide and intermetallic phase precipitation. This yields to lower local corrosion resistance in sea water due to changes in the local content of alloying elements. The precipitation of chromium carbide affects the resistance to the intergranular corrosion and the repassivation behavior. The eutectoidal decomposition of ferritic phase into regenerated austenite and in sigma phase ( α → γ r + σ) results in weakening the resistance to pit nucleation in synthetic sea water. In contrast, such precipitation will not have any significant effect when the treatment temperature is high enough to involve a rapid rehomogenization of depleted zones and ensure a self-healing.

  16. Influence of Sample Pretreatment Methods on the Determination of Trace Oxygen in Iron and Steel

    Science.gov (United States)

    Yasuhara, H.; Shimura, M.; Yoshioka, K.

    1997-04-01

    Removing the oxide film from the sample surface is an important process in analyzing trace oxygen in iron and steel. The depth profiles of oxygen on the surface after electropolishing in CH3COOH - HClO4, CrO3 - H3PO4, and HCl, and chemical polishing by HF- H2O2 are investigated. The thickness of the oxide layer after electropolishing is estimated to be about 3 nm, which is approximately equivalent to 1 mass ppm oxygen. This indicates that the currently available surface polishing methods are inadequate for the analysis of mass ppm or sub-ppm oxygen levels. A surface without an oxide layer is obtained by Ar ion sputtering in a vacuum, but the oxide layer reappears within 1 min when the sample comes into contact with air.

  17. INFLUENCE OF COLD ROLLING TECHNOLOGY ON TEXTURE EVOLUTION OF IF STEEL

    Institute of Scientific and Technical Information of China (English)

    J.X. Li; X.H. Liu; G.D. Wang

    2002-01-01

    Two kinds of cold rolling experiments, single cold rolling and double cold rolling, werecarried out on one titanium stabilized interstitial free (IF) steel that has been warmrolled at ferrite temperature. The main aim was to investigate the evolution of rollingand annealing textures from the well known behavior observed under single cold rollingcondition to the less understood double cold rolling by using orientation distributionfunction (ODF). In the twice cold rolled samples, the annealing texture comprises onlyfirst round of rolling. Accordingly both the once cold rolled sample and the twice coldrolled sample with heavy reduction in the first round of rolling have much complextexture components. They are related to the formation of initial {111} subgrain andthe priority growth of stable {111} nucleus.

  18. The influence of drawing parameters on the properties high-manganese TWIP steel wires

    Directory of Open Access Journals (Sweden)

    Z. Muskalski

    2013-01-01

    Full Text Available The paper presents an experimental analysis of the effect of single draft magnitude in the multi-stage drawing process on the mechanical properties of the wire, and a theoretical process analysis aimed at identifying the causes of the variations in mechanical properties, made using Drawing 2D, a FEM-relying software program of high manganese TWIP steel rolling and stamping processes. It was found that wires drawn with small partial drafts (Gp%=11 % had a larger plasticity reserve, as defined by the R0.2/Rm ratio, as compared with wires drawn with large partial drafts (Gp = 26 %. A drop both in tensile strength Rm and in proof stress R0.2 was also found to occur after a total draft of Gc = 80 % had been exceeded, which was caused by the “strain softening” phenomenon.

  19. Factors influencing the Zn and Mn extraction from pyrometallurgical sludge in the steel manufacturing industry.

    Science.gov (United States)

    Mocellin, J; Mercier, G; Morel, J L; Blais, J F; Simonnot, M O

    2015-08-01

    In this laboratory study, a process has been developed for selectively leaching zinc and manganese from pyrometallurgical sludge produced in the steel manufacturing industry. In the first part, the yield of Zn extraction was studied using four factors and four levels of the Box-Behnken response surface design. The optimum conditions for the step of Zn leaching were determined to be a sulfuric acid concentration of 0.25 mol/L, a pulp density of 10%, an extraction temperature of 20 °C, and three stages of leaching. Under such conditions, 75% of the Zn should be leached. For Mn leaching, the optimum conditions were determined to be a sulfuric acid concentration of 0.25 mol/L, a Na2S2O5/Mn stoichiometry of 1, a leaching time of 120 min and two leaching steps. In this case, 100% of the Mn should be leached. PMID:25958078

  20. Shielding gas influences on laser weldability of tailored blanks of advanced automotive steels

    International Nuclear Information System (INIS)

    The effects of shielding gas types and flow rates on CO2 laser weldability of DP600/TRIP700 steel sheets were studied in this work. The evaluated shielding gases were helium (He), argon (Ar) and different mixtures of He and Ar. Weld penetration, tensile strength and formability (Erichsen test) of laser welds were found to be strongly dependent upon the shielding gas types. The ability of shielding gas in removing plasma plume and thus increasing weld penetration is believed to be closely related to ionization potential and atomic weight which determine the period of plasma formation and disappearance. It was found that the higher helium shielding gas flow rate, the deeper weld penetration and the lower weld width.

  1. Shielding gas influences on laser weldability of tailored blanks of advanced automotive steels

    Energy Technology Data Exchange (ETDEWEB)

    Reisgen, Uwe; Schleser, Markus; Mokrov, Oleg [RWTH Aachen University, Welding and Joining Institute, Pontstr. 49, Aachen (Germany); Ahmed, Essam, E-mail: essam.ahmed@rwth-aachen.de [RWTH Aachen University, Welding and Joining Institute, Pontstr. 49, Aachen (Germany)

    2010-12-15

    The effects of shielding gas types and flow rates on CO{sub 2} laser weldability of DP600/TRIP700 steel sheets were studied in this work. The evaluated shielding gases were helium (He), argon (Ar) and different mixtures of He and Ar. Weld penetration, tensile strength and formability (Erichsen test) of laser welds were found to be strongly dependent upon the shielding gas types. The ability of shielding gas in removing plasma plume and thus increasing weld penetration is believed to be closely related to ionization potential and atomic weight which determine the period of plasma formation and disappearance. It was found that the higher helium shielding gas flow rate, the deeper weld penetration and the lower weld width.

  2. Influence of Heat Treatment on Mercury Cavitation Resistance of Surface Hardened 316LN Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, Steven J [ORNL; Hsu, Julia [Massachusetts Institute of Technology (MIT)

    2010-11-01

    The cavitation-erosion resistance of carburized 316LN stainless steel was significantly degraded but not destroyed by heat treatment in the temperature range 500-800 C. The heat treatments caused rejection of some carbon from the carburized layer into an amorphous film that formed on each specimen surface. Further, the heat treatments encouraged carbide precipitation and reduced hardness within the carburized layer, but the overall change did not reduce surface hardness fully to the level of untreated material. Heat treatments as short as 10 min at 650 C substantially reduced cavitation-erosion resistance in mercury, while heat treatments at 500 and 800 C were found to be somewhat less detrimental. Overall, the results suggest that modest thermal excursions perhaps the result of a weld made at some distance to the carburized material or a brief stress relief treatment will not render the hardened layer completely ineffective but should be avoided to the greatest extent possible.

  3. 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.

  4. Shielding gas influences on laser weldability of tailored blanks of advanced automotive steels

    Science.gov (United States)

    Reisgen, Uwe; Schleser, Markus; Mokrov, Oleg; Ahmed, Essam

    2010-12-01

    The effects of shielding gas types and flow rates on CO 2 laser weldability of DP600/TRIP700 steel sheets were studied in this work. The evaluated shielding gases were helium (He), argon (Ar) and different mixtures of He and Ar. Weld penetration, tensile strength and formability (Erichsen test) of laser welds were found to be strongly dependent upon the shielding gas types. The ability of shielding gas in removing plasma plume and thus increasing weld penetration is believed to be closely related to ionization potential and atomic weight which determine the period of plasma formation and disappearance. It was found that the higher helium shielding gas flow rate, the deeper weld penetration and the lower weld width.

  5. Influence of the austenitic stainless steel microstructure on the void swelling under ion irradiation

    Directory of Open Access Journals (Sweden)

    Rouxel Baptiste

    2016-01-01

    Full Text Available To understand the role of different metallurgical parameters on the void formation mechanisms, various austenitic stainless steels were elaborated and irradiated with heavy ions. Two alloys, in several metallurgical conditions (15Cr/15Ni–Ti and 15Cr/25Ni–Ti, were irradiated in the JANNUS-Saclay facility at 600 °C with 2 MeV Fe2+ ions up to 150 dpa. Resulting microstructures were observed by Transmission Electron Microscopy (TEM. Different effects on void swelling are highlighted. Only the pre-aged samples, which were consequently solute and especially titanium depleted, show cavities. The nickel-enriched matrix shows more voids with a smaller size. Finally, the presence of nano-precipitates combined with a dense dislocation network decreases strongly the number of cavities.

  6. Influence of cryogenic treatment on the wear characteristics of 100Cr6 bearing steel

    Science.gov (United States)

    Sri Siva, R.; Mohan Lal, D.; Kesavan Nair, P.; Jaswin, M. Arockia

    2014-01-01

    A series of reciprocating wear tests were performed on the deep cryogenically treated and conventionally heat-treated samples of 100Cr6 bearing steel to study the wear resistance. The worn surfaces as well as the wear debris were analyzed by scanning electron microscopy. The improvement in wear resistance of the deep cryogenically treated samples ranges from 49% to 52%. This significant improvement in wear resistance can be attributed to finer carbide precipitation in the tempered martensitic matrix and the transformation of retained austenite into martensite. X-ray diffraction analysis shows that the volume fraction of retained austenite in the conventionally heat-treated samples is 14% and that of the deep cryogenically treated samples is only 3%.

  7. Researches Regarding the Influence of Cu Content on Static and Dynamic Properties of Sintered Steels

    Directory of Open Access Journals (Sweden)

    Liviu BRÂNDUŞAN

    2004-02-01

    Full Text Available The utilisation of iron powder in sintered steels subjected to variable loadings was confined because of their low fatigue resistance and the fact that this kind of loading is unknown for the users. Lately, a lot of effort was made to determine the fatigue behaviour and to identify new methods for improving these properties.In this paper are analyse the behaviour of elaborate materials from iron powder, DWP 200.28 with cooper addition, pressed at 600 MPa and sintered at 1120°C for 30 minutes in endogas. The cooper is add to improve the mechanical characteristics, by forming some favourable microstructures and more round pores from the material macrostructure. For this materials tensile resistance, elongation, Young modulus and the number of cycles until failure are analysed. We find that the cooper add say in a different way these properties.

  8. Influence of Gas Flow Rate on the Deposition Rate on Stainless Steel 202 Substrates

    Directory of Open Access Journals (Sweden)

    M.A. Chowdhury

    2012-12-01

    Full Text Available Solid thin films have been deposited on stainless steel 202 (SS 202 substrates at different flow rates of natural gas using a hot filament thermal chemical vapor deposition (CVD reactor. In the experiments, the variations of thin film deposition rate with the variation of gas flow rate have been investigated. The effects of gap between activation heater and substrate on the deposition rate have also been observed. Results show that deposition rate on SS 202 increases with the increase in gas flow rate within the observed range. It is also found that deposition rate increases with the decrease in gap between activation heater and substrate. In addition, friction coefficient and wear rate of SS 202 sliding against SS 304 under different sliding velocities are also investigated before and after deposition. The experimental results reveal that improved friction coefficient and wear rate is obtained after deposition than that of before deposition.

  9. Thermal fatigue of austenitic stainless steel: influence of surface conditions through a multi-scale approach

    International Nuclear Information System (INIS)

    Some cases of cracking of 304L austenitic stainless steel components due to thermal fatigue were encountered in particular on the Residual Heat Removal Circuits (RHR) of the Pressurized Water Reactor (PWR). EDF has initiated a R and D program to understand assess the risks of damage on nuclear plant mixing zones. The INTHERPOL test developed at EDF is designed in order to perform pure thermal fatigue test on tubular specimen under mono-frequency thermal load. These tests are carried out under various loadings, surface finish qualities and welding in order to give an account of these parameters on crack initiation. The main topic of this study is the research of a fatigue criterion using a micro:macro modelling approach. The first part of work deals with material characterization (stainless steel 304L) emphasising the specificities of the surface roughness link with a strong hardening gradient. The first results of the characterization on the surface show a strong work-hardening gradient on a 250 microns layer. This gradient does not evolved after thermal cycling. Micro hardness measurements and TEM observations were intensively used to characterize this gradient. The second part is the macroscopic modelling of INTHERPOL tests in order to determine the components of the stress and strain tensors due to thermal cycling. The third part of work is thus to evaluate the effect of surface roughness and hardening gradient using a calculation on a finer scale. This simulation is based on the variation of dislocation density. A goal for the future is the determination of the fatigue criterion mainly based on polycrystalline modelling. Stocked energy or critical plane being available that allows making a sound choice for the criteria. (author)

  10. Influence of additional alloying with nitrogen on structure and properties of high chromium steel Kh17 after hot rolling

    International Nuclear Information System (INIS)

    A study was made into the structure and mechanical properties of steel Kh17 with 0.16% N after hot rolling under various conditions. It is shown that nitrogen alloying promotes steel transition into a two-phase state (α+γ) in heating above 850 deg C and affects mechanical properties of the steel in a hot rolled state. Impact strength is at its maximum in nitrogen containing steel kh17 if the rolling is in the temperature range of α-phase solid solution. Depending on the temperatures of hot rolling beginning and completion the distinctions in steel microstructure are investigated

  11. Influence of cubic texture intensity of hot rolled ferritic non-oriented electrical steels on the microstructure and texture in the final processed material

    Science.gov (United States)

    Stöcker, A.; Schneider, J.; Scholze, T.; Franke, A.; Hermann, H.; Kawalla, R.

    2015-04-01

    The magnetic properties of non-oriented electrical steels are determined by the microstructure and texture of the material. Besides optimum grain size (microstructure) for low values of specific magnetic losses, a high intensity of θ-fibre texture and low intensity of γ-fibre and α-fibre texture is desirable. Each of the processing steps influences the intensity of the θ-fibre in the final processed material. In this paper the interplay of the various processing steps on the intensity of the θ-fibre is regarded for ferritic Iron-Silicon steels with 2.4 wt.% Si and 3.0 wt.% Si.

  12. Influence of crystallographic texture in X70 pipeline steels on toughness anisotropy and delamination

    Science.gov (United States)

    Al-Jabr, Haytham M.

    The effects of microstructure and crystallographic texture in four commercially-produced API X70 pipeline steels and their relation to planar anisotropy of toughness and delamination were evaluated. The experimental steels were processed through either a hot strip mill, a Steckel mill, or a compact strip mill. Different processing routes were selected to obtain plates with potential variations in the microstructure and anisotropic characteristics. Tensile and Charpy impact testing were used to evaluate the mechanical properties in three orientations: longitudinal (L), transverse (T) and diagonal (D) with respect to the rolling direction to evaluate mechanical property anisotropy. The yield and tensile strengths were higher in the T orientation and toughness was lower in the D orientation for all plates. Delamination was observed in some of the ductile fracture surfaces of the impact samples. To further study the splitting behavior and effects on impact toughness, a modified impact test (MCVN) specimen with side grooves was designed to intensify induced stresses parallel to the notch root and thus facilitate evaluation of delamination. Scanning electron microscopy combined with electron backscattered diffraction (EBSD) were used to evaluate the grain size, microstructural constituents, and crystallographic texture to determine the factors leading to delamination and the anisotropy in toughness. The ferrite grain size is mainly responsible for the differences in DBTTs between the L and T orientations. The higher DBTT in the D orientation observed in pipeline steels is attributed to crystallographic texture. The higher DBTT in the D direction is due to the higher volume fraction of grains having their {100} planes parallel or close to the primary fracture plane for the D orientation. An equation based on a new "brittleness parameter," based on an assessment of grain orientations based on EBSD data, was developed to predict the changes in DBTTs with respect to sample

  13. Influence of localized plasticity on Stress Corrosion Cracking of austenitic stainless steel. Application to IASCC of internals reactor core vessels

    International Nuclear Information System (INIS)

    The surface conditions of the 316L screw connecting vessel internals of the primary circuit of PWR (pressurized water reactor) corresponds to a grinding condition. These screws are affected by the IASCC (Irradiation Assisted Stress Corrosion Cracking). Initiation of cracking depends on the surface condition but also on the external oxidation and interactions of oxide layer with the deformation bands. The first objective of this study is to point the influence of surface condition on the growth kinetic of oxide layer, and the surface reactivity of 304, 316 stainless steel grade exposed to PWR primary water at 340 C. The second objective is to determine influence of strain localization on the SCC of austenitic stainless steels in PWR primary water. Indeed, the microstructure of irradiated 304, 316 grades correspond to a localized deformation in deformation bands free of radiation defects. In order to reproduce that microstructure without conducting irradiations, low cycle fatigue tests at controlled stain amplitude are implemented for the model material of the study (A286 austenitic stainless steel hardened by the precipitation of phase γ'Ni3(Ti, Al)). During the mechanical cycling (after the first hardening cycles), the precipitates are dissolved in slip bands leading to the localization of the deformation. Once the right experimental conditions in low cycle fatigue obtained (for localized microstructure), interactions oxidation / deformation bands are studied by oxidizing pre deformed samples containing deformation bands and non deformed samples. The tensile tests at a slow strain rate of 8 x 10-8 /s are also carried out on pre deformed samples and undeformed samples. The results showed that surface treatment induces microstructural modifications of the metal just under the oxide layer, leading to slower growth kinetics of the oxide layer. However, surface treatment accelerates development of oxides penetrations in metal under the oxide layer. As example, for

  14. 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.

  15. Influence of nickel additions on the corrosion behaviour of low nitrogen 22% Cr series duplex stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Potgieter, J.H. [DST/NRF Centre of Excellence in Strong Materials, School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Private Bag 2050, WITS, Johannesburg (South Africa); Olubambi, P.A. [DST/NRF Centre of Excellence in Strong Materials, School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Private Bag 2050, WITS, Johannesburg (South Africa)], E-mail: peter.olubambi@students.ac.za; Cornish, L.; Machio, C.N. [DST/NRF Centre of Excellence in Strong Materials, School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Private Bag 2050, WITS, Johannesburg (South Africa); Sherif, El-Sayed M. [DST/NRF Centre of Excellence in Strong Materials, School of Physics, University of the Witwatersrand, Johannesburg (South Africa)

    2008-09-15

    Four 22% Cr duplex stainless steel alloys containing varying nickel contents of approximately 5%, 7%, 9% and 13% were melted in a vacuum induction furnace, hot rolled, solution annealed and water quenched. Their corrosion behaviour was investigated in sulphuric acid and sodium chloride solutions using potentiodynamic polarization and chronoamperometric techniques. Increasing nickel contents have an appreciable influence on the observed corrosion behaviour. Polarization curves show similarities in the uniform corrosion behaviour of the alloys in the various solutions, but significant differences in their pitting resistance in chloride environments. Alloy 2209 (22% Cr - 9% Ni) generally exhibited the highest resistance to uniform corrosion, while alloy 2213 (22% Cr - 13% Ni) displayed the best pitting corrosion resistance. X-ray diffraction analysis of the surfaces of the alloys after corrosion in the different media revealed different corrosion products. Scanning electron micrographs revealed that the alloys were differently attacked by chloride ions, with different pit depths and morphologies. The corrosion behaviour exhibited by the alloys was attributed to the influence of nickel on phase modification, microstructural refinement, and the types of films formed in different environments. Uniform corrosion behaviour of the alloys was concluded to be predominantly controlled by phase composition and ratio, while pitting resistance was chiefly controlled by an alloy's nickel contents.

  16. Influence of flowing sodium on creep deformation and rupture behaviour of 316L(N) austenitic stainless steel

    Science.gov (United States)

    Ravi, S.; Laha, K.; Mathew, M. D.; Vijayaraghavan, S.; Shanmugavel, M.; Rajan, K. K.; Jayakumar, T.

    2012-08-01

    The influence of flowing sodium on creep deformation and rupture behaviour of AISI 316L(N) austenitic stainless steel has been investigated at 873 K over a stress range of 235-305 MPa. The results were compared with those obtained from testing in air environment. The steady state creep rates of the material were not influenced appreciably by the testing environments. The time to onset of tertiary stage of creep deformation was delayed in sodium environment. The creep-rupture lives of the material increased in sodium environment, which became more pronounced at lower applied stresses. The increase in rupture life of the material in flowing sodium was accompanied by an increase in rupture ductility. The creep damage on specimen surface as well as inside the specimen was less in specimen tested in sodium. SEM fractographic investigation revealed predominantly transgranular dimple failure for the specimen tested in sodium, whereas predominantly intergranular creep failure was observed in the air tested specimens. Almost no oxidation was observed in the specimens creep tested in the sodium environment. Absence of oxidation and less creep damage cavitation extended the secondary state in liquid sodium tests and lead to increase in creep rupture life and ductility of the material as compared to in air.

  17. Influences of Thermal Martensites and Grain Orientations on Strain-induced Martensites in High Manganese TRIP/TWIP Steels

    Institute of Scientific and Technical Information of China (English)

    Fayun Lu; Ping Yang; Li Meng; Fenge Cui; Hua Ding

    2011-01-01

    Strain-induced martensites in high manganese TRIP/TWIP steels were investigated in the presence of thermal martensites and under the influence of austenitic grain orientation by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). Before deformation, the morphology of α′-M depended mainly on the number of variants and growing period. Regardless of martensite morphologies and deformation, the Kurdjumov-Sachs (K-S) orientation relationships always maintained. The 6 α′-M variants formed from a plate of ε-M were of 3 pairs of twins with a common axis <110>α′ parallel to the normal of {111}γ habit plane to minimize transformation strain. When α′-M could be formed only by deformation, it nucleated at the intersection of ε-M variants and grew mainly in thick ε-M plates. Thick ε plates promoted significantly the α′-M and weakened the influence of grain orientations. During tension, the transformation in <100>-oriented grains was observed to be slower than that in <111>-oriented grains. Deformation twins promoted ε-M formation slightly and had no apparent effect on α′-M. Deformation increased the number of ε-M variants, but reduced that of α′-M variants.

  18. Influence of nickel additions on the corrosion behaviour of low nitrogen 22% Cr series duplex stainless steels

    International Nuclear Information System (INIS)

    Four 22% Cr duplex stainless steel alloys containing varying nickel contents of approximately 5%, 7%, 9% and 13% were melted in a vacuum induction furnace, hot rolled, solution annealed and water quenched. Their corrosion behaviour was investigated in sulphuric acid and sodium chloride solutions using potentiodynamic polarization and chronoamperometric techniques. Increasing nickel contents have an appreciable influence on the observed corrosion behaviour. Polarization curves show similarities in the uniform corrosion behaviour of the alloys in the various solutions, but significant differences in their pitting resistance in chloride environments. Alloy 2209 (22% Cr - 9% Ni) generally exhibited the highest resistance to uniform corrosion, while alloy 2213 (22% Cr - 13% Ni) displayed the best pitting corrosion resistance. X-ray diffraction analysis of the surfaces of the alloys after corrosion in the different media revealed different corrosion products. Scanning electron micrographs revealed that the alloys were differently attacked by chloride ions, with different pit depths and morphologies. The corrosion behaviour exhibited by the alloys was attributed to the influence of nickel on phase modification, microstructural refinement, and the types of films formed in different environments. Uniform corrosion behaviour of the alloys was concluded to be predominantly controlled by phase composition and ratio, while pitting resistance was chiefly controlled by an alloy's nickel contents

  19. Rare earth metals influence on mechanical properties and crack resistance of GP240GH and G17CrMo5-5 cast steels

    Directory of Open Access Journals (Sweden)

    M. Gajewski

    2009-10-01

    Full Text Available This paper presents results of research on modification influence of REM on mechanical properties and crack resistance of GP240GH cast carbon steel and G17CrMo5-5 high-temperature cast steel. The tests have been performed on successive industrial melts. The rare earth metals were put into the ladle during tapping of heat melt from the furnace. Each time ca 2000 kg of liquid metals were modified. Because of this the amount of sulphur in the cast steel was decreased and the non-metallic inclusion morphology was significantly changed. There were tested mechanical properties (Re,Rm, plastic properties (A5,Z and impact strength (KV, and on the basis of the three-point bend test the KJC stress intensity factor was evaluated. It was noticed that the REM modification brings essential increase of impact strength as well as fracture toughness determined by KJC factor.

  20. Update of the water chemistry effect on the flow-accelerated corrosion rate of carbon steel: influence of hydrazine, boric acid, ammonia, morpholine and ethanolamine

    International Nuclear Information System (INIS)

    The influence of the water chemistry on Flow-Accelerated Corrosion (FAC) affecting carbon steel components has been studied for many years and is relatively well known and taken into account by the models. Nonetheless, experimental studies were conducted in the last few years at EDF on the CIROCO loop in order to check the influence of the water chemistry parameters (hydrazine, boric acid, ammonia, morpholine and ethanolamine) on the FAC rate of carbon steel in one phase flow conditions. The hydrazine impact on the FAC rate was shown to be minor in EDF's chemistry recommendation range, compared to other parameters' effects such as the pH effect. The presence of boric acid in the nominal secondary circuit conditions was negligible. Finally, as expected, the nature of the chemical conditioning (ammonia, morpholine or ethanolamine) did not modify the FAC rate, the influencing chemical variable being the at-temperature pH in one-phase flow conditions. (author)

  1. The influence of loading on the corrosion of steel in cracked ordinary Portland cement and high performance concretes

    Science.gov (United States)

    Jaffer, Shahzma Jafferali

    Most studies that have examined chloride-induced corrosion of steel in concrete have focused on sound concrete. However, reinforced concrete is seldom uncracked and very few studies have investigated the influence of cracked concrete on rebar corrosion. Furthermore, the studies that have examined the relationship between cracks and corrosion have focused on unloaded or statically loaded cracks. However, in practice, reinforced concrete structures (e.g. bridges) are often dynamically loaded. Hence, the cracks in such structures open and close which could influence the corrosion of the reinforcing steel. Consequently, the objectives of this project were (i) to examine the effect of different types of loading on the corrosion of reinforcing steel, (ii) the influence of concrete mixture design on the corrosion behaviour and (iii) to provide data that can be used in service-life modelling of cracked reinforced concretes. In this project, cracked reinforced concrete beams made with ordinary Portland cement concrete (OPCC) and high performance concrete (HPC) were subjected to no load, static loading and dynamic loading. They were immersed in salt solution to just above the crack level at their mid-point for two weeks out of every four (wet cycle) and, for the remaining two weeks, were left in ambient laboratory conditions to dry (dry cycle). The wet cycle led to three conditions of exposure for each beam: (i) the non-submerged region, (ii) the sound, submerged region and (iii) the cracked mid-section, which was also immersed in the solution. Linear polarization resistance and galvanostatic pulse techniques were used to monitor the corrosion in the three regions. Potentiodynamic polarization, electrochemical current noise and concrete electrical resistance measurements were also performed. These measurements illustrated that (i) rebar corroded faster at cracks than in sound concrete, (ii) HPC was more protective towards the rebar than OPCC even at cracks and (iii) there

  2. The influence of strain rate on the microstructure transition of 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Chen, A.Y. [School of Material Science and Engineering, Shanghai Institute of Technology, 201400 (China); Department of Mechanical Engineering, Hong Kong Polytechnic University (Hong Kong); Ruan, H.H.; Wang, J.; Chan, H.L.; Wang, Q. [Department of Mechanical Engineering, Hong Kong Polytechnic University (Hong Kong); Li, Q. [Physics Department, Chinese University of Hong Kong (Hong Kong); Lu, J., E-mail: jianlu@cityu.edu.hk [Department of Manufacturing Engineering and Engineering Management, City University of Hong Kong (Hong Kong)

    2011-05-15

    In the top-down approach to tailor the microstructures of materials via plastic deformation, the strain rate plays a significant role. This paper systematically investigates the deformation mechanisms of 304 stainless steel subjected to surface impacts over a wide range of strain rates (10-10{sup 5} s{sup -1}). Based on comprehensive analysis of X-ray diffraction and electron microscopy observations, we found that the strain rate between 10 and 10{sup 3} s{sup -1} only activated dislocation motions and {alpha}'-martensite transformations, resulting in nanocrystallines and ultra-fine grains. However, higher strain rates (10{sup 4}-10{sup 5} s{sup -1}) produced a high density of twin bundles with nanoscale thickness in the bulk material. The transition from dislocation-mediated mechanism to twinning-mediated mechanism was interpreted in terms of the magnitude of the applied stress, which was calculated from the explicit finite-element simulation with the use of the Johnson-Cook model. A critical twinning stress, determined from the infinite separation of Shockley partials, renders the transition point. Deformation twinning occurs when the applied stress exceeds this critical twinning stress. Larger stress leads to thinner and denser twin lamellae. Conversely, the stress below the transition point can only induce dislocation motions and {alpha}'-martensite transformations.

  3. Influence of yttrium on laser surface alloying organization of 40Cr steel

    Institute of Scientific and Technical Information of China (English)

    WU Anqi; LIU Qibin; QIN Shuijie

    2011-01-01

    In order to improve the performance of the metal rollers,Mo+Y2O3 alloy powders were used to coat uniformly on the surface of 40Cr steel roller substrates for the laser surface alloying treatment by a CO2 laser,The results showed that many good consequences were obtained after adding the rare earth oxide Y2O3.The crystal grains of the alloy layer were significantly refine& The boundary of crystal grains was strengthened.The uniformity and density of the rnicrostructure were increased.The hardness and wearing resistance of the alloy layer were considerably improved.The valence electron structure analysis of the alloy layer was made by the empirical electron theory of solids and molecules (EET).The calculated results demonstrated that Y should be mixed in the first stage and Fe should be in the eighteenth hybrid bands.The analyzed outcomes illustrated that the electron theory of the solid solution shows the strengthening effect on the alloying layer,which has enhanced bond and confirmed the experimental results.

  4. Recrystallization in ultra low carbon (ULC) steel: influence of the as-deformed microstructure and texture

    Energy Technology Data Exchange (ETDEWEB)

    Verlinden, B.; Samajdar, I.; Houtte, P. van [KU Leuven, Heverlee (Belgium). Dept. MTM; Kestens, L.

    1998-10-01

    Development of recrystallization texture in an ultra low carbon (ULC) steel was studied at four (50-90%) different cold rolling reductions. During deformation, a steady increase in {alpha} fibre (RD// left angle 110 right angle) was observed, while {gamma} fibre (ND// left angle 111 right angle) increased from 0-50% reduction but then did not change significantly. In the recrystallization texture, however, a steady and significant increase of {gamma} fibre, but no changes in {alpha}, was noted with increased reductions. Based on the as deformed state, two physical parameters were identified, which may explain the changes in recrystallization texture with strain. Those being: (1) spacings (as measured along ND) of {gamma}/{alpha} oriented deformed bands and (2) relative ability of such bands to form recrystallized grains. An estimation of (2) for different orientations may be obtained from their respective nucleation factors (N{sub i}, defined as the number of grains of a particular orientation per deformed band of the same orientation, measured/estimated along normal direction). Evidently, a decrease in {gamma} band spacing and/or an increase/decrease in {gamma}/{alpha} nucleation factors will strengthen the {gamma} recrystallization texture. With increased reductions, spacings of the {gamma} bands decreased - mainly from the geometrical considerations. On the other hand, above 70% reduction, nucleation factors for {alpha} bands, especially for I {l_brace}112{r_brace} left angle 110 right angle component, dropped significantly. (orig.) 12 refs.

  5. Influence of Workpiece Material on Tool Wear Performance and Tribofilm Formation in Machining Hardened Steel

    Directory of Open Access Journals (Sweden)

    Junfeng Yuan

    2016-04-01

    Full Text Available In addition to the bulk properties of a workpiece material, characteristics of the tribofilms formed as a result of workpiece material mass transfer to the friction surface play a significant role in friction control. This is especially true in cutting of hardened materials, where it is very difficult to use liquid based lubricants. To better understand wear performance and the formation of beneficial tribofilms, this study presents an assessment of uncoated mixed alumina ceramic tools (Al2O3+TiC in the turning of two grades of steel, AISI T1 and AISI D2. Both workpiece materials were hardened to 59 HRC then machined under identical cutting conditions. Comprehensive characterization of the resulting wear patterns and the tribofilms formed at the tool/workpiece interface were made using X-ray Photoelectron Spectroscopy and Scanning Electron Microscopy. Metallographic studies on the workpiece material were performed before the machining process and the surface integrity of the machined part was investigated after machining. Tool life was 23% higher when turning D2 than T1. This improvement in cutting tool life and wear behaviour was attributed to a difference in: (1 tribofilm generation on the friction surface and (2 the amount and distribution of carbide phases in the workpiece materials. The results show that wear performance depends both on properties of the workpiece material and characteristics of the tribofilms formed on the friction surface.

  6. Influence of stress on creep deformation properties of 9-12Cr ferritic creep resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, K.; Sawada, K.; Kushima, H. [National Institute for Materials Science (Japan)

    2008-07-01

    Creep deformation property of 9-12Cr ferritic creep resistant steels was investigated. With decrease in stress, a magnitude of creep strain at the onset of accelerating creep stage decreased from about 2% in the short-term to less than 1% in the longterm. A time to 1% total strain was observed in the transient creep stage in the short term regime, however, it shifted to the accelerating creep stage in the long-term regime. Life fraction of the times to 1% creep strain and 1% total strain tended to increase with decrease in stress. Difference in stress dependence of the minimum creep rate was observed in the high- and low-stress regimes with a boundary condition of 50% of 0.2% offset yield stress. Stress dependence of the minimum creep rate in the high stress regime was equivalent to a strain rate dependence of the flow stress evaluated by tensile test, and a magnitude of stress exponent, n, in the high stress regime decreased with increase in temperature from 20 at 550 C to 10 at 700 C. On the other hand, n value in the low stress regime was about 5, and creep deformation in the low stress regime was considered to be controlled by dislocation climb. Creep rupture life was accurately predicted by a region splitting method by considering a change in stress dependence of creep deformation. (orig.)

  7. Influence of weld discontinuities on strain controlled fatigue behavior of 308 stainless steel weld metal

    International Nuclear Information System (INIS)

    Detailed investigations have been performed for assessing the importance of weld discontinuities in strain controlled low cycle fatigue (LCF) behavior of 308 stainless steel (SS) welds. The LCF behavior of 308 SS welds containing defects was compared with that of type 304 SS base material and 308 SS sound weld metal. Weld pads were prepared by shielded metal arc welding process. Porosity and slag inclusions were introduced deliberately into the weld metal by grossly exaggerating the conditions normally causing such defects. Total axial strain controlled LCF tests have been conducted in air at 823 K on type 304 SS base and 308 SS sound weld metal employing strain amplitudes in the range from ±0.25 to ±0.8 percent. A single strain amplitude of ±0.25 percent was used for all the tests conducted on weld samples containing defects. The results indicated that the base material undergoes cyclic hardening whereas sound and defective welds experience cyclic softening. Base metal showed higher fatigue life than sound weld metal at all strain amplitudes. The presence of porosity and slag inclusions in the weld metal led to significant reduction in life. Porosity on the specimen surface has been found to be particularly harmful and caused a reduction in life by a factor of seven relative to sound weld metal

  8. Influence of Surface Nano-structured Treatment on Pack Boriding of H13 Steel

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In order to lower the boriding temperature of hot work steel H13, method of surface mechanical attrition treatment (SMAT), which can make the grain size of the surface reach nano-scale, was used before pack boriding. The growth of the boride layer was studied in a function of boriding temperature and time. By TEM (transmission electron microscopy), SEM (scanning electron microscopy), XRD (x-ray diffraction) and microhardness tests, the grain size, thermal stability of the nano-structured (NS) surface and the thickness,appearance, phases of the surface boride layer were studied. Kinetic of boriding was compared between untreated samples and treated samples. Results showed that after SMAT, the boride layer was thicker and the hardness gradient was smoother. Furthermore, after boriding at a low temperature of 700℃ for 8 h, a boride layer of about 5 μm formed on the NS surface. This layer was toothlike and wedged into the substrate, which made the surface layer combine well with the substrate. The phase of the boride layer was Fe2B. Research on boriding kinetics indicated that the activation energy was decreased for the treated samples.

  9. Influence of reverted austenite on the texture and magnetic properties of 350 maraging steel

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, Hamilton F.G., E-mail: hamilton@ufc.br [Universidade Federal do Ceará, Campus do Pici-Bloco 729, CEP 60440-554 Fortaleza, CE (Brazil); Silva, Jean J. [Universidade Federal do Ceará, Campus do Pici-Bloco 729, CEP 60440-554 Fortaleza, CE (Brazil); Silva, Manoel R. [Universidade Federal de Itajubá, Campus Sede Itajubá/IFQ- Instituto de Física e Química, Itajubá, MG (Brazil); Gomes da Silva, Marcelo J., E-mail: mgsilva@ufc.br [Universidade Federal do Ceará, Campus do Pici-Bloco 729, CEP 60440-554 Fortaleza, CE (Brazil)

    2015-11-01

    The aging temperature to improve magnetic properties in Maraging-350 steel (Mar-350) is limited by the onset of austenite reversion. The traditional process of cooling after aging is to remove the piece from the oven and then to air cool it. The purpose of this research was to characterize the reverted austenite and to investigate the effect of cooling below the martensite start temperature (M{sub s}) on the magnetic properties. The Mar350 samples aged at temperatures above 550 °C, and subsequently cooled in liquid nitrogen presented less austenite than samples cooled in air, resulting in higher magnetization saturation and a lower coercive force. A combination of optical microscopy (OM), X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) techniques were used to characterize the presence of reverted austenite. The crystallographic texture of both martensite and reverted austenite were analyzed. The texture of the reverted austenite coincides with the texture of the parent austenite indicating that a phenomenon of texture memory is present. - Highlights: • Cooling maraging samples in liquid nitrogen reduces reverted austenite fraction. • Retained austenite increases coercive force and decreases saturation magnetization. • Reverted and parent austenites have the same crystallographic texture. • Memory effect found during reversion transformation.

  10. Extrinsic Influence of Environment-Induced Degradation on Load Carrying Capacity of Steel Beams

    Science.gov (United States)

    Gowda, Sunil; Patnaik, A.; Payer, J.; Srivatsan, T. S.

    2015-11-01

    In this paper, the results of a study aimed at evaluating the strength of wide-flanged beams subjected to corrosion-induced damage, modeled using a standard finite element program (ABAQUS) is presented and discussed. Typical beams in consideration were subjected to different cases of corrosion-induced damage, such as non-uniform and varying degree of material loss that simulates pitting corrosion. Many variables, such as (a) shape of pitting damage, (b) location of pits along the length of the beam, (c) number of pits, and (d) depth of pits, were considered to facilitate a better understanding of the load carrying capacity of steel I-beams having damage quite similar to pitting damage to the web. The results are compared with an "as-new" beam for purpose of evaluation of the reduction in strength due to environment-induced deterioration. A "corrosion strength reduction factor (CSRF)" is introduced to help identify the reduction in load carrying capacity as a consequence of both height and depth of the damage due to corrosion. The results are presented in charts for purpose of practical beam design.

  11. Influence of delta ferrite content and welding variables on notch toughness of austenitic stainless steel weldments

    International Nuclear Information System (INIS)

    Two series of austenitic stainless steel weld deposits are evaluated to explore the separate contributions of delta ferrite content and welding variables to apparent notch toughness. Charpy-V and Dynamic Tear test determinations are used for weld deposit comparisons. The investigation represents the first part of a two part study of variable weld notch toughness in preirradiation and postirradiation conditions for the temperature range 750F (240C) to 11000F (5930C). Weld Series 1, represented by four 21/2-in. thick AISI Type 308 weld deposits (shielded metal arc) exhibited delta ferrite contents ranging from ferrite number 5.2 to 19.0. Variations in delta ferrite content within this range did not appear to be a major factor in observed toughness trends. Weld Series 2, formed of six 1-in. thick AISI Type 316 weld deposits (submerged arc), indicated that welding parameters and minor differences in flux lot formulations can contribute to variable notch toughness. Initial radiation tests demonstrate that a fluence of 8 to 9 x 1019 n/cm2 greater than 0.1 MeV at 500 to 5500F (260 to 2880C) can produce large reductions in Charpy-V notch ductility for Types 308 and 316 weld deposits

  12. Development of accelerated evaluation method for microbially influenced corrosion resistance of stainless steels; Sutenresu ko no taibiseibutsu fushokusei jinsoku hyoka shikenho no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Amaya, H.; Miyuki, H. [Sumitomo Metal Industries Ltd., Osaka (Japan). Iron and Steel Research Lab.

    1995-02-15

    Mechanism of microbially influenced corrosion (MIC) of stainless steels in natural sea water was clarified and based on this mechanism, accelerated evaluation method for MIC resistance was developed experimentally. In regard to the artificial simulation of corrosion behavior of natural sea water, the ennoblement of corrosion potential of stainless steel in natural sea water was simulated by adding oxidizing enzyme glucose oxidase (GOD) with glucose in artificial sea water. The most appropriate test conditions to simulate MIC experimentally and in a short time were GOD concentration 1mg/l, glucose concentration 10g/l and temperature less than 50{degree}C. The results of multi crevice test of stainless steel under calculated optimum condition showed good agreement with the crevice corrosion behavior in natural sea water in a short time. This accelerated evaluation method may be used to study the MIC behavior of SUS304 steel in fresh water. In future, it is expected that this method can be used for the evaluation of MIC behavior of other materials except stainless steel. 26 refs., 10 figs., 3 tabs.

  13. Influence of Cu alloying on hot ductility of C-Mn-Al and Ti-Nb microalloyed steels

    Directory of Open Access Journals (Sweden)

    Comineli, O.

    2005-12-01

    Full Text Available A beneficial effect of the copper on the hot ductility was observed in Ti-Nb microalloyed steels over the temperature range 800-1,000 °C at the cooling rate of 0.4 °C/s, but no influence at the cooling rate of 4 °C/s. Precipitates containing Nb and Ti were present whose size was coarser in the Cu-bearing grade as cooled at 0.4 °C/s. Cu-bearing precipitates were not found. In the C-Mn-Al steel, no influence of the copper on the hot ductility was recorded, but CuS particles were detected. Two mechanisms are proposed to explain the positive influence of the copper in the microalloyed steel. The first is that the copper atoms in the solid solution affect the activity of the carbon and the nitrogen analogically to the previously observed effect of the silicon, enhancing the precipitation at high temperatures, and another mechanism that the copper atoms can prolong the lifetime of vacancies generated by straining assisting the formation of TiNb-vacancy complexes and thereby coarsening the precipitates.

    Se ha observado un efecto beneficioso del cobre sobre la ductilidad en caliente del acero microaleado al Ti-Nb, en el rango de temperaturas 800-1.000 °C. La influencia fue observada a velocidades de enfriamiento bajas, 0,4 °C/s, mientras que a 4 °C/s no se aprecia. En el acero C-Mn-Al, la influencia de cobre no fue detectada. En el acero microaleado se detectó la presencia de precipidados que contienen niobio y titanio, la dimensión de los cuales es mayor cuando se enfría a 0,4 °C/s. En este acero no se detectó la presencia de precipitados con contenidos de cobre, en contraste con el acero C-Mn-Al, donde sí se observaron partículas de CuS. Se proponen dos mecanismos para explicar la influencia positiva del cobre en aceros microaleados. El primero es el aumento de la actividad de carbono y nitrógeno en austenita debido a presencia de átomos de cobre en solución sólida, con el mismo efecto que el silicio, el cual aumenta la

  14. The influence of delta (a) ferrite on the irradiation effects in type-304 stainless steel weldment

    International Nuclear Information System (INIS)

    Differences in the high energy ion induced defects microstructure of BCC a-ferrite and FCC austenite matrix, and the effects of a-ferrite on the Vickers micro-hardness increase after irradiation were investigated for Type 304 stainless steel weldments containing two different a-ferrite contents: ferrite number(FN) 5.5 and 8.5, respectively. Specimens were irradiated to 1.5 dpa by 8 MeV Fe+4 ions using a Tandem Vande-Graft accelerator (flux : 4.3 x 1010 ion/cm2. sec, fluence : 0.83 x 1015 ion/cm2) at room temperature. TRIM 95 results showed that a peak damage appeared at 1.5 μm in depth with 0.7 μm full width at half maximum (FWHM), and these results could have been confirmed by TEM on irradiation induced defects (IID) distribution. Clear differences in the size and number of IID in the form of black dots (size: 5-10 nm) and loops were observed between the austenitic matrix and a-ferrite, where the size of IID was far larger in FCC matrix than BCC a-ferrite. Vickers micro-hardness (Hv) test results showed that a -ferrite has increased about five times higher than austenitic matrix after irradiation. This observation was used to explain the higher Vickers micro-hardness increase due to irradiation in the high FN weldment than the lower FN weldment, i.e., 44% increase for 8.5 FN to 36% increase for 5.5 FN after irradiation

  15. Influence of Temperature on Typical Texture Distribution in Primary Recrystallization Matrix of 3% Si CGO Silicon Steel

    OpenAIRE

    Li, Zhi-Chao; Dang, Ning; Mi, Zhen-li

    2016-01-01

    OM (optical microscopy) and EBSD (electron backscatter diffraction) techniques were used to study microstructure and texture distribution during primary recrystallization under different intermediate annealing temperatures in CGO silicon steels. The effect of intermediate annealing temperature on texture distribution in 3% Si electrical steel was analyzed. The results indicate that the microstructure in primary recrystallization matrix of CGO silicon steel is comprised of equiaxed ferrite gra...

  16. Light-weight steels based on iron-aluminium - influence of micro alloying elements (B, Ti, Nb) on microstructures, textures and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Bruex, U.; Frommeyer, G. [Dept. of Materials Technology, Max-Planck-Inst. fuer Eisenforschung GmbH, Duesseldorf (Germany); Jimenez, J. [Centro Nacional de Investigaciones Metalurgicas (C.S.I.C.), Madrid (Spain)

    2002-12-01

    The influence of the micro alloying elements B, Ti and Nb on the recrystallization texture and mechanical properties of iron aluminium light-weight steels, particularly with reference to their improved deep drawing properties was investigated. Depending on the combination of the alloying elements the microstructures of the investigated micro alloyed Fe-6Al steels are influenced by grain refinement. Likewise, variable combinations of micro alloying elements differently affect the texture. Generally, the mechanical properties are improved. However, small amounts of B, Ti and Nb cause superior deep drawing and stretch forming properties of these iron aluminium light-weight steels. The microstructures of various micro alloyed cold rolled Fe-6Al steel sheets were evaluated by optical microscopy, scanning electron microscopy (SEM) inclusively EDAX and X-ray diffraction. Texture measurements were performed using a goniometer with a closed Eulerian cradle and analysed by ODF calculations. Tensile tests were carried out at room temperature and 200 C, respectively. The deep drawing behaviour was determined by performing cupping tests and digitalised strain analysis. (orig.)

  17. Influence of Water Pollution on MIC of Stainless Steel 304L

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The influence of water pollution and welding defects on MIC (microbiologically influenced corrosion) was studied. The open circuit potential (OCP) was measured during MIC test. It was found that OCP shifted to a higher level when the system was inoculated with bacteria while the OCP of those samples in water without bacteria was kept at a low level. The OCP decreased dramatically when MIC started in polluted water. Combination of weld defect-heat tint, polluted water and adding bacteria causes MIC happen at high rate. Some elements inside the tubercle were analyzed with EDXA. The pits and biofilm were observed with SEM. Microbiological analysis revealed the difference of bacteria between corroded and uncorroded samples.

  18. Influence of nitrogen on the stress corrosion cracking resistance of austenitic stainless steels in chloride environment; Influence de l'azote sur la resistance a la corrosion sous contrainte d'aciers inoxydables austenitiques en milieu chlorure

    Energy Technology Data Exchange (ETDEWEB)

    Teysseyre, S

    2001-11-01

    The aim of this study is to investigate the influence of nitrogen additions on the Stress Corrosion Cracking (SSC) resistance of austenitic stainless steel in chloride environment. The investigation was carried out in two part: first, an experimental investigation with model industrial steels was carried out and secondly, numerical simulations based on the Corrosion Enhanced Plasticity Model were developed. Both slow strain rate tensile tests and constant load test of the different steels in boiling MgCl{sub 2} (153 deg C) at free potential show that, for a given plastic strain rate, nitrogen addition increases the critical stress for crack initiation without influencing the crack propagation rate. We observed that the creep rate under constant load was affected by the nitrogen content. As a consequence, the SCC behaviour (cracks density and propagation rate) depends on the nitrogen content. We thus confirm that the nitrogen content influences the corrosion - deformation interaction mechanisms via its positive contribution to the flow stress. These experimental results are reproduced semi-quantitatively by means of numerical simulations at the scale of crack. - dislocation interactions. The presence of nitrogen is modelled by an increased lattice friction stress, which in turn affects the dynamics of crack tip shielding by dislocation pile-ups. We conclude that nitrogen addition in austenitic stainless steels increases the SC crack initiation stress in proportion of the increased flow stress, without penalty in terms of SC crack propagation rate. (author)

  19. The influence of organic structure and rare earth metal cation on the corrosion efficiency observed on AS1020 steel compared with La(4OHCin3

    Directory of Open Access Journals (Sweden)

    Marianne Seter

    2015-01-01

    Full Text Available Whilst the corrosion protection of steel in aqueous chloride environments by the rare earth inhibitor lanthanum 4-hydroxycinnamate is well known, the influence of the structural variation of the organic component as well as the nature of the metal centre has not previously been addressed. Herein we show that praseodymium 4-hydroxy cinnamate is comparable to its lanthanum counterpart in aqueous solution. On the other hand, cerium 4-hydroxycinnamate and lanthanum 2-hydroxycinnamate show poor corrosion protection performance while lanthanum 3-hydroxycinnamate provides a level of inhibition between these. These differences are shown to be related to the speciation in solution and are postulated to be linked to steric influences which are likely to affect the bonding environment within the rare earth compound itself, as well as its bonding with the steel substrate.

  20. Influence of rare earth elements on solidification behavior of a high speed steel for roll using differential scanning calorimetry

    Institute of Scientific and Technical Information of China (English)

    WANG Mingjia; CHEN Lei; WANG Zixi; BAO Er

    2011-01-01

    The influence of rare earths (RE) on solidification behavior of a high speed steel for roll was investigated by using differential scanning calorimetry (DSC) in combination of microstructure analysis.It was found that the sequence of solidification was L→γ,L→γ+MC,L→γ+M2C,L→γ+M6C,respectively.The start temperature and the latent heat liberated by unit mass of L→γ and L→γ+MC increased with increase of RE addition,indicating that RE could trigger the crystallization of the primary γ and the MC carbide more effectively.The promoting effect of RE on the heterogeneous nucleation was believed to be an important cause of this effect.Grain refinement,discontinuous network of eutectic carbides and disperse and finer MC were observed in the samples with RE addition,moreover,RES could act as the heterogeneous nucleus of the MC.RE addition was favorable for stable M6C at the expense of the metastable M2C.

  1. Influence of tempered microstructures on the transformation behaviour of cold deformed and intercritically annealed medium carbon low alloy steel

    Directory of Open Access Journals (Sweden)

    Kenneth Kanayo Alaneme

    2010-06-01

    Full Text Available This research is focused on understanding the role of microstructural variables and processing parameters in obtaining optimised dual phase structures in medium carbon low alloy steels. Tempered Martensite structures produced at 300, 500, and 650 °C, were cold rolled to varied degrees ranging from 20 to 80% deformation. Intercritical annealing was then performed at 740, 760, and 780 °C for various time duration ranging from 60 seconds to 60 minutes before quenching in water. The transformation behaviour was studied with the aid of optical microscopy and hardness curves. From the results, it is observed that microstructural condition, deformation, and intercritical temperatures influenced the chronological order of the competing stress relaxation and decomposition phase reactions which interfered with the rate of the expected α → γ transformation. The three unique transformation trends observed are systematically analyzed. It was also observed that the 300 and 500 °C tempered initial microstructures were unsuitable for the production of dual structures with optimized strength characteristics.

  2. Analysis of the variation in nanohardness of pearlitic steel: Influence of the interplay between ferrite crystal orientation and cementite morphology

    International Nuclear Information System (INIS)

    The influence of the relative orientation of the ferrite crystallite lattice and the cementite lamellae on the hardness of pearlitic steel has been investigated by a combination of nanoindentation and electron microscopy (electron back scatter diffraction (EBSD) and scanning electron microscopy (SEM)). Three pearlitic samples, each with a different interlamellar spacing, and one ferritic sample were nanoindented. Although the hardness of the ferritic sample is very similar at different spots on the sample, a large variation in hardness is obtained on each of the pearlitic samples. It has been found that this variation cannot be accounted for solely by the variation in interlamellar spacing and is related to differences in ferrite crystal orientation. As to explain the observed large variation in hardness, the ferrite crystal orientation was considered relative to the cementite lamellae orientation by calculation of the distance dislocations can glide between adjacent lamellae in the slip direction. However, no clear correlation was found for a scaling of this orientation factor with the hardness. Possible interpretations of this discrepancy are suggested

  3. Influence and role of ethanol minor constituents of fuel grade ethanol on corrosion behavior of carbon steel

    International Nuclear Information System (INIS)

    Highlights: • The pitting factors of the minor contents of ethanol are acetic acid, Cl and H2O. • Formic acid in ethanol promotes general corrosion. • The H2O content in fuel-grade-ethanol (FGE) affects the corrosion morphology. • Acetic acid generates iron acetate, which has high solubility in FGE environments. • A pitting mechanism based on the rupture of passive film is proposed. - Abstract: The influences of organic acids, chloride and water on the corrosion behavior of carbon steel in fuel grade ethanol (FGE) environments were investigated by immersion testing in simulated FGE. The roles of acetic acid, chloride and water in pitting corrosion were studied by using X-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES) and electrochemical experiments. The results indicated that iron acetate is generated on oxide film. Iron(II) acetate shows high solubility in FGE environments. The sites where iron(II) acetate is existed become preferential anodic sites, and chloride promotes anodic dissolution at such sites

  4. Influence of the electrical sliding speed on friction and wear processes in an electrical contact copper stainless steel

    Science.gov (United States)

    Bouchoucha, A.; Chekroud, S.; Paulmier, D.

    2004-02-01

    Among the various parameters that influence the friction and wear behaviour of a copper-stainless steel couple crossed by an electrical current and in a dry contact is the sliding speed. The tests were carried out under ambient environment and the sliding speed was in the range of 0.2-8 ms -1. The electrical current intensity was varied from 0 to 40 A and held constant during each experiment. The normal load was maintained constant corresponding to an average Hertzian stress of 10 7 Pa. It appears that the friction coefficient and the wear rate increase at first with the speed, reach their maximums, then slowly decrease and tend to constant values. Over the entire range of sliding speeds two types of wear are observed. These latters are essentially mild wear as long as hard debris do not appear at the interface and severe wear when debris consisting of oxides or oxide metal mixture become big enough, they are removed from the surface and have abrasive effect. The results are discussed in terms of observations of wear debris size and composition, wear track study, metallographic study of worn surfaces and friction and electrical contact resistance records.

  5. Microbial Corrosion in Linepipe Steel Under the Influence of a Sulfate-Reducing Consortium Isolated from an Oil Field

    Science.gov (United States)

    AlAbbas, Faisal M.; Williamson, Charles; Bhola, Shaily M.; Spear, John R.; Olson, David L.; Mishra, Brajendra; Kakpovbia, Anthony E.

    2013-11-01

    This work investigates microbiologically influenced corrosion of API 5L X52 linepipe steel by a sulfate-reducing bacteria (SRB) consortium. The SRB consortium used in this study was cultivated from a sour oil well in Louisiana, USA. 16S rRNA gene sequence analysis indicated that the mixed bacterial consortium contained three phylotypes: members of Proteobacteria ( Desulfomicrobium sp.), Firmicutes ( Clostridium sp.), and Bacteroidetes ( Anaerophaga sp.). The biofilm and the pits that developed with time were characterized using field emission scanning electron microscopy (FE-SEM). In addition, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and open circuit potential (OCP) were used to analyze the corrosion behavior. Through circuit modeling, EIS results were used to interpret the physicoelectric interactions between the electrode, biofilm and solution interfaces. The results confirmed that extensive localized corrosion activity of SRB is due to a formed biofilm in conjunction with a porous iron sulfide layer on the metal surface. X-ray diffraction (XRD) revealed semiconductive corrosion products predominantly composed of a mixture of siderite (FeCO3), iron sulfide (Fe x S y ), and iron (III) oxide-hydroxide (FeOOH) constituents in the corrosion products for the system exposed to the SRB consortium.

  6. Analysis of the variation in nanohardness of pearlitic steel: Influence of the interplay between ferrite crystal orientation and cementite morphology

    Energy Technology Data Exchange (ETDEWEB)

    Debehets, Jolien, E-mail: jolien.debehets@mtm.kuleuven.be [Department of Materials Engineering, KU Leuven, University of Leuven, Kasteelpark Arenberg 44 bus 2450, B-3001 Leuven (Belgium); Tacq, Jeroen [Department of Materials Engineering, KU Leuven, University of Leuven, Kasteelpark Arenberg 44 bus 2450, B-3001 Leuven (Belgium); Favache, Audrey; Jacques, Pascal [Institute of Mechanics, Materials and Civil Engineering, Université catholique de Louvain, Place Sainte Barbe 2 L5.02.02, 1348 Louvain-la-Neuve (Belgium); Seo, Jin Won; Verlinden, Bert; Seefeldt, Marc [Department of Materials Engineering, KU Leuven, University of Leuven, Kasteelpark Arenberg 44 bus 2450, B-3001 Leuven (Belgium)

    2014-10-20

    The influence of the relative orientation of the ferrite crystallite lattice and the cementite lamellae on the hardness of pearlitic steel has been investigated by a combination of nanoindentation and electron microscopy (electron back scatter diffraction (EBSD) and scanning electron microscopy (SEM)). Three pearlitic samples, each with a different interlamellar spacing, and one ferritic sample were nanoindented. Although the hardness of the ferritic sample is very similar at different spots on the sample, a large variation in hardness is obtained on each of the pearlitic samples. It has been found that this variation cannot be accounted for solely by the variation in interlamellar spacing and is related to differences in ferrite crystal orientation. As to explain the observed large variation in hardness, the ferrite crystal orientation was considered relative to the cementite lamellae orientation by calculation of the distance dislocations can glide between adjacent lamellae in the slip direction. However, no clear correlation was found for a scaling of this orientation factor with the hardness. Possible interpretations of this discrepancy are suggested.

  7. Influence of Thermal Homogenization Treatment on Structure and Impact Toughness of H13 ESR Steel

    Institute of Scientific and Technical Information of China (English)

    MA Dang-shen; ZHOU Jian; CHEN Zai-zhi; ZHANG Zhong-kan; CHEN Qi-an; LI De-hui

    2009-01-01

    The as-cast microstrueture of H13 ESR ingot and the influence of high temperature diffusion treatment on the structure and impact toughness have been investigated. The results show that the dendrite arm spacing gradually becomes wide from the surface to the center of ingot, and the large primary carbide particles always exist in interdendritic segregation areas; by means of high temperature diffusion treatment of ingot prior to hot forging, the banded segregation is nearly eliminated, the annealed structure is more uniform and the isotropic properties have been improved remarkably.

  8. Influence of chemistry and hot rolling conditions on high permeability non-grain oriented silicon steel

    International Nuclear Information System (INIS)

    This paper discusses the influence of chemical composition on the final electromagnetic properties in higher permeability material. Furthermore, the effect of the hot rolling practice and the end of austenite transformation temperature range on the hot band microstructure is described. The magnetic polarization J 5000 better than 1.7 T, using hot rolling conditions 40 mm transfer bar thickness, finish mill entry temperature 1000 deg. C, and finishing temperature 800-840 deg. C and after decarburization heat treatment and grain growth treatment, was obtained

  9. The influence of non-metallic elements in the mechanical properties of 20 Mn Mo Ni 55 steel

    International Nuclear Information System (INIS)

    Usual methods for determining non-metallic elements in steels are studied. Those methods are: a) Standard methods of ASTM and ISO and b) Modern and fast methods of detection, non-standard. The steel used was 20 Mn Mo Ni 55. (E.G.)

  10. Influence of silver additions to type 316 stainless steels on bacterial inhibition, mechanical properties, and corrosion resistance

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Tseng, I-Sheng; Møller, Per;

    2010-01-01

    Bacterial contamination is a major concern in many areas. In this study, silver was added to type 316 stainless steels in order to obtain an expected bacteria inhibiting property to reduce the occurrence of bacterial contamination. Silver-bearing 316 stainless steels were prepared by vacuum melti...

  11. Investigation of the influence of different cutting procedures on the global and local magnetic properties of non-oriented electrical steel

    Energy Technology Data Exchange (ETDEWEB)

    Naumoski, H., E-mail: Hristian.Naumoski@daimler.com [Daimler AG, R& D, 89081 Ulm (Germany); Riedmüller, B.; Minkow, A.; Herr, U. [Institute of Micro- and Nanomaterials, University Ulm, 89069 Ulm (Germany)

    2015-10-15

    The process of manufacturing iron cores for electric machines out of electrical steel sheets can strongly affect the magnetic properties of the material. In order to better understand the influence of cutting on the iron losses, a characterization of the magnetization behavior near the cutting edge is needed. The local magnetic properties of the material are modified by the cutting process which leads to an increase in the iron losses measured for 5 mm wide ring core samples by nearly 160% at low inductions. We present investigations on the effect of cutting by observation of the magnetic domain structure of 0.35 mm thick non-oriented electrical steel. By using the magneto-optical Kerr-effect on a ring samples the local magnetic properties of the material after processing are characterized in the form of domain wall displacements under an applied external ac-field. The influence of various cutting techniques on the magnetic properties was studied before and after stress relief annealing. This method allows a quantitative analysis of the influence of different cutting techniques on the micro-magnetic properties of non-oriented electrical steel for rotating machines. - Highlights: • The influence of cutting on the magnetic properties of electrical steel was studied. • The magnetic behavior at the cut edge was investigated using the Kerr-effect. • The micro-magnetic results correlate well with the integral magnetic measurements. • Stress relief annealing recovers the magnetic properties of the cut material. • The method allows quantitative determination of the extension of the affected zone.

  12. The influence of the hardening coolant agent on the properties of hot rolled bars of the steel 42CrMo4

    Directory of Open Access Journals (Sweden)

    M. Stańczyk

    2014-10-01

    Full Text Available In the work the influence results of two different hardening coolant agents on the basic mechanical proprieties and microstructure of the round hot rolled bars were presented. The bars of 42CrMo4 steel were exposed to analysis, and for those bars in the hardening process, water and modern pro-ecological polymer cooling agents Aqua Quench MK were used.

  13. The Influence of Microalloying and Thermal Treatment on Mechanical Properties of Billets and Pipes Prepared from Microalloyed Steel C0.2Mn2Cr1

    International Nuclear Information System (INIS)

    The influence of doping with Ca, Ba and B on processing and mechanical properties of tubes prepared from steel C0.2Mn2Cr1 was investigated. Significant increase of plasticity and impact strength was observed. Optimal technological parameters of broaching and reducing processes for obtaining high strength was established and the critical reduction needed for cavity formation at the tip of mandrel was determined. Cavity formation parameters were established via hot-twisting and tapered sample rolling tests. (author)

  14. Influence of pH on the electrochemical behaviour of a duplex stainless steel in highly concentrated LiBr solutions

    OpenAIRE

    Guiñon Pina, Virginia; Igual Muñoz, Anna Neus; García Antón, José

    2011-01-01

    The objective is to study the influence of pH on the corrosion and passive behaviour of duplex stainless steels (DSS) using potentiodynamic measurements, potentiostatic tests and electrochemical impedance spectroscopy (EIS). DSS are spontaneously passive in heavy brine LiBr solutions. Under potentiostatic conditions at applied anodic potentials within the passive domain an equivalent circuit with two time constants is the most suitable model to describe the corrosion mechanism in the interfac...

  15. The influence of pluronic P123 micelles on corrosion behaviour of steel in cement extract and bulk matrix properties of cement paste

    OpenAIRE

    Koleva, D.A.; Denkova, A.G.; Hu, J.; van Breugel, K

    2012-01-01

    The influence of Pluronic P123 (PEO20-PPO20-PEO70) micelles (of 10 nm size) on the corrosion behaviour of low carbon steel in cement extract (CE) was studied using electrochemical impedance spectroscopy (EIS) and potentio-dynamic polarisation (PDP). Additionally, mercury intrusion porosimetry (MIP) was emplo ed to derive the impact of admixed micelles on porosity and pore-size distribution of cement paste. The motivation for carrying out this investigation has two main aspects: first, previou...

  16. Strain rate sensitivity of automotive sheet steels : influence of plastic strain, strain rate, temperature, microstructure, bake hardening and pre-strain

    OpenAIRE

    Larour, Patrick

    2010-01-01

    This experimental work shows the different parameters influencing the strain rate sensitivity behaviour of automotive sheet steel grades in crash conditions. Most investigations have been performed in the strain rate range [0,001-200/s] and temperature range [233-373K] with servohydraulic tensile testing machines. Additional Split-Hopkinson bar testing results up to 1000/s have also been included at room temperature. The focus has been laid on the “apparent” strain rate sensitivity, determine...

  17. Influence of respiratory substrate in carbon steel corrosion by a Sulphate Reducing Prokaryote model organism.

    Science.gov (United States)

    Dall'agnol, Leonardo T; Cordas, Cristina M; Moura, José J G

    2014-06-01

    Sulphate Reducing Prokaryotes (SRP) are an important group of microorganisms involved in biocorrosion processes. Sulphide production is recognized as a fundamental cause of corrosion and nitrate is often used as treatment. The present work analyses the influence of respiratory substrates in the metal, from off-shore installations, SRP influenced corrosion, using Desulfovibrio desulfuricans ATTC 27774 as model organism, since this can switch from sulphate to nitrate. Open Circuit Potential over 6days in different conditions was measured, showing an increase around 200 and 90mV for the different media. Tafel plots were constructed allowing Ecorr and jcorr calculations. For SRP in sulphate and nitrate media Ecorr values of -824 and -728mV, and jcorr values of 2.5 and 3.7μAcm(-2), respectively, were attained indicating that in nitrate, the resultant corrosion rate is larger than in sulphate. Also, it is shown that the equilibrium of sulphide in the solution/gas phases is a key factor to the evolution of corrosion Nitrate prevents pitting but promotes general corrosion and increases the corrosion potential and iron dissolution 40 times when compared to sulphate. Our results demonstrate that nitrate injection strategy in oil fields has to be considered carefully as option to reduce souring and localized corrosion.

  18. The influence of the structure of the metal load removal from liquid steel in electric arc furnaces

    Science.gov (United States)

    Pǎcurar, Cristina; Hepuť, Teodor; Crisan, Eugen

    2016-06-01

    One of the main technical and economic indicators in the steel industry and steel respectively the development it is the removal of liquid steel. This indicator depends on several factors, namely technology: the structure and the quality metal load, the degree of preparedness of it, and the content of non-metallic material accompanying the unit of drawing up, the technology for the elaboration, etc. research has been taken into account in drawing up steel electric arc furnace type spring EBT (Electric Bottom taping), seeking to load and removing components of liquid steel. Metal load has been composed of eight metal grades, in some cases with great differences in terms of quality. Data obtained were processed in the EXCEL spreadsheet programs and MATLAB, the results obtained being presented both graphically and analytically. On the basis of the results obtained may opt for a load optimal structure metal.

  19. The influence of arc plasma electric and laser treatment on the structure and properties of the high speed steel

    Directory of Open Access Journals (Sweden)

    W. Bochnowski

    2009-07-01

    Full Text Available The examination of the structure, hardness and abrasion resistance of surface layer of high speed steel: HS 2-10-1-8, HS 6-5-2 and HS 10-2-5-8 after arc plasma and laser welding are presented in the paper. They are compared with the properties obtained after conventional hardening. Diode laser of continuous operation and GTAW (Gas Tungsten Arc Welding method were used. As a result of concentrated energy beam treatment applied to a steels surface layer, the structures characteristic of rapid solidification / crystallization process were obtained. The treatment of the steel by arc plasma electric with a single remelted track about 7 mm width does not lead to growth of the mechanical and tribological properties of high speed steels. The growth of microhardness as well as low the coefficient Archard of the high speed steel after remelting on the surface single track about 6 mm width by diode laser using can be obtained.

  20. The Influence of Calcined Clay Pozzolan, Low-Cao Steel Slag and Granite Dust On the Alkali-Silica Reaction in Concrete

    Directory of Open Access Journals (Sweden)

    James Sarfo-Ansah

    2015-08-01

    Full Text Available The influence of low CaO steel slag, calcined clay and granite dust on the alkali-silica reaction was investigated over a period of 35 days under accelerated curing conditions. The mineral admixtures were used to replace varying portions of high alkali Portland limestone cement up to an admixture content of 25% in order to study their effect on the alkali-silica reaction (ASR. Portland limestone cement used for the study had a total Na2Oeq of 4.32. XRD analysis of hydrated mortar bar samples confirmed the formation of an expansive sodium silica gel in the reference Portland cement mortar bar as the agent responsible for ASR. Stable calcium silicates were formed in the mortar bars containing calcined clay in increasing quantities whilst the presence of the sodium silicate gel decreased.The occurrence of these stable silicates in hydrated samples containing steel slag and granite dust was however minimal, compared to calcined clay cement mortars. The highest expansion was recorded for granite dust mortar bars, reaching a maximum of 25.98% at 35 days. Mortar-bar expansion decreased as calcined clay content in the cement increased;mortar bars with 25% calcined clay were the least expansive recording expansion less than 0.1% at all test ages. Whilst the expansion was reduced by between 42.5% and 107.8% at 14 days with increasing calcined clay content, expansion rather increased between 36.8% and 169.5% at 14 days with increasing granite dust content.Steel slag mortar bars experienced reduction in 14 days expansion between 14.3% - 46.2%.The study confirms that steel slag and calcined clay pozzolan have greater influence on ASR in mortar bars than granite dust and shows that calcined clay and low CaO steel slag could be considered as remedial admixtures for ASR at replacement levels of 25% and 15% respectively.

  1. Influence of temperature histories during reactor startup periods on microstructural evolution and mechanical properties of austenitic stainless steel irradiated with neutrons

    Science.gov (United States)

    Kasahara, Shigeki; Kitsunai, Yuji; Chimi, Yasuhiro; Chatani, Kazuhiro; Koshiishi, Masato; Nishiyama, Yutaka

    2016-11-01

    This paper addresses influence of two different temperature profiles during startup periods in the Japan Materials Testing Reactor and a boiling water reactor upon microstructural evolution and mechanical properties of austenitic stainless steel irradiated with neutrons to about 1 dpa and 3 dpa. One of the temperature profiles was that the specimens experienced neutron irradiation in both reactors, under which the irradiation temperature transiently increased to 290 °C from room temperature with increasing reactor power during reactor startup periods. Another was that the specimens were pre-heated to about 150 °C prior to the irradiation to suppress the transient temperature increase. Tensile tests at 290 °C and Vickers hardness tests at room temperature were carried out, and their microstructures were observed by FEG-TEM. Difference of the temperature profiles was observed obviously in interstitial cluster formation, in particular, growth of Frank loops. Although influence of neutron irradiation involving transient temperature increase to 290 °C from room temperature on the yield strength and the Vickers hardness is buried in the trend curves of existing data, the influence was also found certainly in increment of in yield strength, existence of modest yield drop, and loss of strain hardening capacity and ductility. As a result, Frank loops, which were observed in austenitic stainless steel irradiated at doses of 1 dpa or more, seemed to have important implications regarding the interpretation of not irradiation hardening, but deformation of the austenitic stainless steel.

  2. The influence of drawing speed on structure changes in high carbon steel wires

    Directory of Open Access Journals (Sweden)

    M. Suliga

    2015-01-01

    Full Text Available In the paper the influence of the drawing speed on structure changes has been assessed. The Scanning Electron Microscope investigation confirmed that for wires drawn with high total draft, exceeding 80 %, makes it impossible to clearly assess the impact of drawing technology on structural changes in the drawn wires. Thus, to assess the structural changes necessary to apply quantitative methods. On the basis of examination of the wire structure by measuring of electrical resistance, the structure changes in drawn wires has been determined. It has been shown that the increase of drawing speed, especially above 15 m/s, causes an increase in structure defect, with a decline in platelet orientation of cementite in drawn wires.

  3. Influence of HVOF coating on the HCF of 300M low alloy steel

    Institute of Scientific and Technical Information of China (English)

    DENG; Chun-ming; LIU; Min; ZHOU; Ke-song; SONG; Jin-bing; WU; Chao-qun; KUANG; Min

    2005-01-01

    The ultimate methods for solving the contamination of Cr6+ is to replace the Cr electroplating with other techniques, thermal spray provides one of the best choices among those alternative techniques. The influence of coatings upon the fatigue performance of substrate, however,should be labeled as an important factor at some high level applications. The effects of both coatings manufactured by HVOF and Cr electroplating respectively on the fatigue performance of substrate are investigated in this article. These results show that the fatigue limit strength at P= 50 %of thermal spray coating is 750 MPa in comparing with fatigue limit 726 MPa for substrate, and the fatigue life increase 25%- 150% when comparing with fatigue life of substrate at different stress levels. The fatigue life increases in the stress scope of 750-850 MPa even the area of thermal spray coating is subtracted. Cr eleetroplating coating reduces the fatigue life by 70%- 95% and the fatigue limit is only 600 MPa. Fracture analysis reveals that the main fracture is initiated at the subsurface, which is 0.2-0.5 mm away from substrate surface. The analysis also observes that the crack in the Cr electroplating propagates through the interface and finally into the substrate which hastens the formation of crack origin and the extension of crack in the substrate, however, the crack in the thermal spray coating deflects at the interface, spreads along the interface, as a result,the crack forming in the coatings has no negative influence on the main crack initiator and crack extension in the substrate.

  4. The influence of cyclic straining on the work hardening behavior of AISI 304 stainless steel bars in multiple-pass drawing

    Energy Technology Data Exchange (ETDEWEB)

    Carballo Siqueira Correa, Elaine [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais, Rua Espirito Santo 35, Centro, 30160-030 Belo Horizonte, Minas Gerais (Brazil)], E-mail: elaine@demet.ufmg.br; Aguilar, Maria Teresa Paulino [Department of Materials and Civil Construction, Federal University of Minas Gerais, Rua Espirito Santo 35, Centro, 30160-030 Belo Horizonte, Minas Gerais (Brazil); Cetlin, Paulo Roberto [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais, Rua Espirito Santo 35, Centro, 30160-030 Belo Horizonte, Minas Gerais (Brazil)], E-mail: pcetlin@demet.ufmg.br

    2007-11-15

    The occurrence of strain softening in drawn low carbon steel bars, as a consequence of cyclic torsion, was previously observed in terms of changes in the mechanical properties of the bars and in the drawing stress, bringing out the possibility of employing cyclic straining in order to improve multiple-stage forming operations. In the present paper, the influence of the structural features of the drawn material on the strain softening phenomenon was analyzed. A commercial AISI 304 stainless steel was used in the experiments. Drawing was carried out in five passes. Cyclic torsion was conducted between the last two stages of drawing and between every drawing pass. In addition to the evaluation of the drawing stress, microstructural and X-ray diffraction analyses were performed, allowing the examination and the calculation of the amount of martensite formed during plastic deformation. Contrasting with the low carbon steel investigation, torsion did not lead to changes in the drawing stress of the AISI 304 stainless steel, for both experimental procedures. The quantitative phase analysis revealed that, even though a considerable deformation value was applied to the material, the amount of martensite formed in cyclic torsion was very low.

  5. Maraging steel - highest strength steels with simple heat treatment for difficult application purposes

    International Nuclear Information System (INIS)

    The lecture concerns the composition of the 18% NiCoMo (maraging) steels, the conversion behaviour and influence of various alloy elements, thermal treatment and its influence on the change of dimension behaviour; comparison of the thermal treatment of maraging steels with tempering steels, influence of trace elements and the way of melting on the mechanical properties, advantages and disadvantages of this group of steel, introduction of newer high-strength maraging steels, their composition and mechanical properties. (orig.)

  6. 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.)

  7. CHANGES IN DISTRIBUTION OF STEEL PRODUCTS

    OpenAIRE

    Beata Œlusarczyk

    2009-01-01

    Steel industry is one of the most globalized branch, globalization has had the influence on iron ore supply, steel production and distribution as well. In last years, steel products distribution process has changed significantly, because of rising competitiveness due to common world market influence and main global players actions. The paper presents changes in steel products distribution in Poland focusing on main steel producers activity in distribution as well as distributors response on n...

  8. Microbiologically influenced corrosion of galvanized steel by Desulfovibrio sp. and Desulfosporosinus sp. in the presence of Ag–Cu ions

    Energy Technology Data Exchange (ETDEWEB)

    Ilhan-Sungur, Esra, E-mail: esungur@istanbul.edu.tr [Istanbul University, Faculty of Science, Department of Biology, 34134 Vezneciler, Istanbul (Turkey); Unsal-Istek, Tuba [Istanbul University, Faculty of Science, Department of Biology, 34134 Vezneciler, Istanbul (Turkey); Cansever, Nurhan [Yıldız Technical University, Faculty of Chemistry-Metallurgy, Metallurgical and Materials Engineering Department, 34210 Esenler, Istanbul (Turkey)

    2015-07-15

    The effects of Ag–Cu ions on the microbiologically induced corrosion of galvanized steel in the presence of Desulfovibrio sp. and Desulfosporosinus sp. were investigated. The corrosion behavior of galvanized steel was analyzed by potentiodynamic polarization and electrochemical impedance spectroscopy. The biofilm, corrosion products and Ag–Cu ions on the surfaces were investigated by using scanning electron microscopy, energy dispersive X-ray spectrometry and elemental mapping. The biofilm layer formed by the Desulfovibrio sp. was stable covering the all surface of galvanized steel coupons, while that by Desulfosporosinus sp. was intermittent, highly porous and heterogeneous. It was found that both of the sulfate reducing bacteria species accelerated corrosion of the galvanized steel. However, it was detected that Desulfosporosinus sp. was more corrosive for galvanized steel than Desulfovibrio sp. Scanning electron microscopy images showed that Desulfovibrio sp. and Desulfosporosinus sp. in biofilm clustered into patches on the galvanized steel surface when the culture contained toxic Ag–Cu ions. The ions affected the growth of the sulfate reducing bacteria strains in different ways and hence the corrosion behaviors. It was observed that the Ag–Cu ions affected negatively growth of Desulfosporosinus sp. especially after 24 h of exposure leading to a decrease in the corrosion rate of galvanized steel. However, Desulfovibrio sp. showed more corrosive effect in the presence of the ions according to the ions-free culture. Energy dispersive X-ray spectrometry analysis showed that corrosion products on the surfaces were mainly composed of Zn, S, Na, O and P. - Highlights: • Galvanized steel was corroded by Desulfosporosinus sp. and Desulfovibrio sp. • Desulfosporosinus sp. is more corrosive than Desulfovibrio sp. • The Ag–Cu ions affected corrosion behavior of Desulfosporosinus sp. and Desulfovibrio sp. on galvanized steel.

  9. Influence of the carbon content on the phase composition and mechanical properties of P92-type steel

    Science.gov (United States)

    Dudko, V. A.; Fedoseeva, A. E.; Belyakov, A. N.; Kaibyshev, R. O.

    2015-11-01

    The deformation behavior and the microstructure evolution under the creep of 10Kh9V2MFBR steel (Russian analog of the P92 steel) (in wt %, Fe-8.9% Cr-0.05% Si-0.2% Mn-1.9% W-0.5% Mo-0.25% V-0.07Nb-0.08% N-0.01% B) with the standard (0.1%) and lowered (0.018%) carbon contents have been investigated. After the heat treatment, which included normalizing at 1050°C and tempering at 720-750°C, carbides M 23 C 6 and carbonitrides M(C,N) are formed in the 10Kh9V2MFBR steel, while in the 02Kh9V2MFBR steel (modified P92 steel), carbides M 23 C 6, nitrides M 2N, and carbonitrides M(C,N) as well as δ-ferrite (23%) were found. The measurements of hardness and tensile tests at room and elevated temper-atures did not reveal substantial distinctions in the short-term mechanical properties of both steels. The hardness of steels after tempering was 220 HB. At the same time, the creep characteristics of the steels were found to be different. A decrease in the carbon content leads to an increase in the long-term creep strength and creep limit at 650°C for short-term tests with time-to-fracture shorter than 103 h. The time to fracture of steels with various carbon contents is almost the same in long-term creep tests. Factor responsible for such effect of carbon on the creep strength are discussed.

  10. Influence of Axial Load Ratio on Shear Behavior of Through-Diaphragm Connections of Concrete-Filled Square Steel Tubular Columns

    Institute of Scientific and Technical Information of China (English)

    Zhang Guangtai张广泰; Han Jianhong韩建红; Rong Bin荣 彬; Apostolos Fafitis

    2015-01-01

    Nonlinear finite element analysis and parametric studies were carried out to study the influence of axial load ratio on the shear behavior of the through-diaphragm connections of concrete-filled square steel tubular col-umns. The analysis reveals that smaller axial load ratio can improve the shear bearing capacity and ductility while larger axial load ratio will decrease the shear behavior of the through-diaphragm connections. The parametric stud-ies indicate that the axial load ratio should be limited to less than 0.4 and its influence should be considered in the analysis and design of such connections.

  11. The influence of cooling rate on the microstructure of stainless steel alloys

    International Nuclear Information System (INIS)

    The emergence of high energy density welding, laser surface modification and rapid solidification as commonly used metallurgical processing techniques has greatly increased the range of cooling rates that can be accessed during the solidification of metals and alloys. The microstructures which develop during these rapid cooling conditions may be significantly different from those which develop during low cooling rate conditions as the result of access to new metastable phases with the additional kinetic limitations that accompany rapid solidification. This investigation explores the influence of cooling rate on a series of seven ternary alloys which span the line of two-fold saturation in the Fe-Ni-Cr system. High speed electron beam surface melting was used to resolidify these alloys at scan speeds up to 5 m/s. The resulting cooling rates were estimated from dendrite arm spacing measurements and were confirmed by heat flow modeling to vary from 7 x 100 degree C/s to 8 x 106 degree C/s. The microstructures that developed from each solidification condition were examined using optical metallography, electron microprobe analysis, scanning electron microscopy and a vibrating sample magnetometer. These results were used to create diagrams to predict the primary mode of solidification, the ferrite content and the complex microstructural morphologies which develop as a function of interface velocity and composition. 158 refs., 90 figs., 45 tabs

  12. Exploration of the influence of welding variables on notch ductility of irradiated austenitic stainless steel welds

    International Nuclear Information System (INIS)

    Postirradiation notch ductility and fracture toughness (K/sub J/) trends of AISI Type 308 weld deposits were explored for radiation exposures in the range of 260 to 6490C. The welds were produced by the shielded metal arc (SMA) process and represented compositional variations (CRE vs non-CRE) and controlled delta ferrite content variations. Fracture toughness determinations were made with fatigue precracked Charpy-V specimens and J-Integral assessment procedures. Specimen irradiations were conducted in EBR-II and UCRR reactors. Large postirradiation decreases in Charpy-V (C/sub V/) energy absorption and fracture toughness were observed. The possibility for K/sub J/ values to be reduced below 88 MPa√m (80 ksi√in.) by moderate fluence exposures was demonstrated. The SMA weld with CRE appeared more sensitive to radiation than a non-CRE Type 308 submerged arc (S/A) weld. An influence of delta ferrite content on 260 or 6490C radiation resistance was not found. Fracture toughness assessments revealed high weld sensitivity to testing rate: a 2 : 1 difference in K/sub J/ level was observed between static vs dynamic test conditions

  13. The influence of the oxygen equivalent in a gas-mixture on the structure and toughness of microalloyed steel weldments

    OpenAIRE

    RADICA PROKIC-CVETKOVIC; ANDJELKA MILOSAVLJEVIC; ALEKSANDAR SEDMAK; OLIVERA POPOVIC

    2006-01-01

    Testings were carried out on two steels. The first was microalloyed with Nb and second with Ti, Nb and V. The impact toughness of weld metals of these steels was evaluated using an instrumented Charpy pendulum. Five different gas mixtures (Ar, CO2, O2) were used to determine the optimal gas shielded metal arc process for both steels. The oxygen equivalent was used as a representative parameter of a mixture to follow, in particularly, its effect on the microstructure, toughness and crack propa...

  14. Influence of high pressure hydrogen environment on tensile and fatigue properties of stainless steels at low temperatures

    Science.gov (United States)

    Ogata, T.

    2012-06-01

    Hydrogen environment embrittlement (HEE) of stainless steels in the environment of high pressure and low temperature hydrogen gas was evaluated using a very simple mechanical properties testing procedure. In the method, the high-pressure hydrogen environment is produced just inside the hole in the specimen. In this work, the effects of HEE on fatigue properties for austenitic stainless steels SUS304L and SUS316L were evaluated at 298 and 190 K. The effects of HEE on the tensile properties of higher strength stainless steels, such as strain-hardened 316, SUS630, and other alloys, SUH660 and Alloy 718 were also examined. The less effect of HEE on fatigue properties of SUS316L and tensile properties of strain-hardened 316 were observed compared with SUS304L and other steels at room temperature and 190 K.

  15. Influence of niobium on the hardening phenomenon and wear in the manganese steel (12% Mn destined for the railway

    Directory of Open Access Journals (Sweden)

    Maouche Hichem

    2014-06-01

    Full Text Available This study relates to the manufacture of austenitic manganese steel for the heart switching crossings of railways in all industrial countries where heavy loads are moved by rail. This steel is characterized by a high surface hardness service yard caused by the phenomenon of hardening. According to the microstructure formed after quenching, the transformation of austenite into martensite during working, determine the operating life. The rate of transformation of austenite into martensite can force a compromise between ductility and wear resistance of the steel in order to withstand large forces without breaking. The objective of this study is to improve the resistance to abrasion and friction to cast state and after heat treatment by the addition of niobium. This study permitted to develop a new shade of manganese steel can be integrated into the production of heart of railway switches with better lifecycle.

  16. The influence of the oxygen equivalent in a gas-mixture on the structure and toughness of microalloyed steel weldments

    Directory of Open Access Journals (Sweden)

    RADICA PROKIC-CVETKOVIC

    2006-03-01

    Full Text Available Testings were carried out on two steels. The first was microalloyed with Nb and second with Ti, Nb and V. The impact toughness of weld metals of these steels was evaluated using an instrumented Charpy pendulum. Five different gas mixtures (Ar, CO2, O2 were used to determine the optimal gas shielded metal arc process for both steels. The oxygen equivalent was used as a representative parameter of a mixture to follow, in particularly, its effect on the microstructure, toughness and crack propagation energy of the weld metal. For these investigated steels, the optimum gas mixture was established (5 % CO2, 0.91 % O2, balance Ar, which provided the maximum crack propagation energy, due to the microstructurewhich consisted dominantly of acicular ferrite.

  17. Analysis the influence of drawing process parameters on the amount of retained austenite in trip steel wires

    Directory of Open Access Journals (Sweden)

    Z. Muskalski

    2013-01-01

    Full Text Available The paper presents a theoretical analysis of the process of drawing TRIP-effect steel wires involving simulation of the drawing process. The process was run following two variants, with small and large partial drafts for three drawing speeds: 1,11; 0,23 and 0,005 m/s. The investigations carried out allowed a relationship between the amount of retained austenite and strain intensity and strain rate to be established for TRIP steel wires drawn.

  18. Influence of phosphorous and boron on dynamic recrystallization and microstructures of hot-rolled interstitial free steel

    International Nuclear Information System (INIS)

    This paper examines the effects of phosphorous (P) and boron (B) of Nb-Ti added interstitial free (IF) steel on dynamic recrystallization, mechanical properties and microstructures. For this purpose, four Nb-Ti added IF steels that contain different contents of P and B were selected. The dynamic recrystallization behavior was investigated using hot compression testing. Mechanical properties and microstructures of pilot hot-rolled IF steel sheet were analyzed as well using uni-axial tensile test and electron back-scattered diffraction (EBSD) following pilot hot rolling experiment. It has been found that B strongly retarded dynamic recrystallization of the IF steel in the temperature range of 900-1100 deg. C. However, P did not delay dynamic recrystallization at 1100 deg. C. The effect of P on dynamic recrystallization was less than that of B. EBSD analysis revealed that absence of P and B induced fine ferrite grain size and many high angle grain boundaries. The ferrite grain size of P and B free IF steel was 46.4% smaller than that of IF steel having 0.1% of P and 0.001% of B

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

    Energy Technology Data Exchange (ETDEWEB)

    Hald, J. [DONG Energy (Denmark)]|[Vattenfall Europe AG, Berlin (Germany)]|[DTU Mechanical Engineering (Denmark); Danielsen, H.K. [DTU Mechanical Engineering (Denmark)

    2008-07-01

    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 hightemperature 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. The Z-phase nucleation process by Cr-diffusion into pre-existing MN nitrides is rate controlling for the Z-phase transformation. More work is needed before effects of chemical composition on the nucleation process can be reliably modeled. Careful control of the Z-phase precipitation process has led to the design of experimental 12%Cr martensitic steels strengthened by Z-phase. 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.)

  20. Analysis on the Deflection Angle of Columnar Dendrites of Continuous Casting Steel Billets Under the Influence of Mold Electromagnetic Stirring

    Science.gov (United States)

    Wang, Xincheng; Wang, Shengqian; Zhang, Lifeng; Sridhar, Seetharaman; Conejo, Alberto; Liu, Xuefeng

    2016-11-01

    In the current study, the deflection angle of columnar dendrites on the cross section of steel billets under mold electromagnetic stirring (M-EMS) was observed. A mathematical model was developed to define the effect of M-EMS on fluid flow and then to analyze the relationship between flow velocities and deflection angle. The model was validated using experimental data that was measured with a Tesla meter on magnetic intensity. By coupling the numerical results with the experimental data, it was possible to define a relationship between the velocities of the fluid with the deflection angle of high-carbon steel. The deflection angle of high-carbon steel reached maximum values from 18 to 23 deg for a velocity from 0.35 to 0.40 m/s. The deflection angles of low-carbon steel under different EM parameters were discussed. The deflection angle of low-carbon steel was increased as the magnetic intensity, EM force, and velocity of molten steel increased.

  1. Measuring the Influence of Pearlite Dissolution on the Transient Dynamic Strength of Rapidly Heated Plain Carbon Steels

    Science.gov (United States)

    Mates, Steven; Stoudt, Mark; Gangireddy, Sindhura

    2016-05-01

    Carbon steels containing ferrite-pearlite microstructures weaken dramatically when pearlite dissolves into austenite on heating. The kinetics of this phase transformation, while fast, can play a role during dynamic, high-temperature manufacturing processes, including high-speed machining, when the time scale of this transformation is on the order of the manufacturing process itself. In such a regime, the mechanical strength of carbon steel can become time dependent. The present work uses a rapidly heated, high-strain-rate mechanical test to study the effect of temperature and time on the amount of pearlite dissolved and on the resulting transient effect on dynamic strength of a low and a high carbon (eutectoid) steel. Measurements indicate that the transient effect occurs for heating times less than about 3 s. The 1075 steel loses about twice the strength compared to the 1018 steel (85 MPa to 45 MPa) owing to its higher initial pearlite volume fraction. Pearlite dissolution is confirmed by metallographic examination of tested samples. Despite the different starting pearlite fractions, the kinetics of dissolution are comparable for the two steels, owing to the similarity in their initial pearlite morphology.

  2. Study of structural transformations occuring in low carbon chromium-molybdenum ferritic steels: influence of small additions of vanadium and niobium

    International Nuclear Information System (INIS)

    This study has been carried out on several low carbon chromium-molybdenum ferritic steels: 2,25%0C to 13000C. In the case of alloys with high chromium concentration and additions of vanadium and niobium, the austenitic transformation is partial, and heat treating at higher temperatures results in increased delta transformation, a phenomenon which is accentuated by an important sensitivity to decarburization. Austenitic transformation during cooling leads to two types of CCT curves according to chromium content. Variations in chemical composition and austenitizing temperature significantly modify these diagrams, in particular those of the niobium stabilized steels. The morphology of the structures produced are very diverse, without important presence of residual austenite. The tempering behaviour in anisothermal and isothermal conditions was followed, and the temperature range limits within which precipitation reactions occur were determined in view of characterizing for each alloy the different types of precipitates formed and their influence on the mechanical resistance of the alloy after tempering

  3. Influence of the pulsed plasma treatment on the corrosion resistance of the low-alloy steel plated by Ni-based alloy

    Science.gov (United States)

    Dzhumaev, P.; Yakushin, V.; Kalin, B.; Polsky, V.; Yurlova, M.

    2016-04-01

    This paper presents investigation results of the influence of high temperature pulsed plasma flows (HTPPF) treatment on the corrosion resistance of low-alloy steel 0.2C-Cr-Mn- Ni-Mo cladded by the rapidly quenched nickel-based alloy. A technique that allows obtaining a defect-free clad layer with a good adhesion to the substrate was developed. It is shown that the preliminary treatment of steel samples by nitrogen plasma flows significantly increases their corrosion resistance in the conditions of intergranular corrosion test in a water solution of sulfuric acid. A change of the corrosion mechanism of the clad layer from intergranular to uniform corrosion was observed as a result of sub-microcrystalline structure formation and homogeneous distribution of alloying elements in the plasma treated surface layer thus leading to the significant increase of the corrosion resistance.

  4. Study of the influence of liquid sodium on the mechanical behavior of T91 steel in liquid sodium

    International Nuclear Information System (INIS)

    We studied the sensitivity of T91 steel to embrittlement by liquid sodium. An experimental procedure was set up to proceed to mechanical testing in sodium under an inert atmosphere. The introduction of a liquid sodium pre-exposure step prior to mechanical testing enabled the study of both the wettability of T91 by sodium and the structure of the sodium steel/interface as a function of the exposure parameters. The mechanical properties of T91 steel are significantly reduced in liquid sodium provided the wetting conditions are good. The use of varying oxygen and hydrogen concentrations suggests that oxygen plays a major role in enhancing the wettability of T91. The sensitivity of the embrittlement to strain rate and temperature was characterized. These results showed the existence of a ductile to brittle transition depending on both parameters. Its characterization suggests that a diffusion step is the limiting rate phenomenon of this embrittlement case. TEM and EBSD analysis of arrested cracks enabled us to establish that the fracture mode is inter-lath or intergranular. This characteristic is coherent with the crack path commonly reported in liquid metal embrittlement. A similar procedure was applied to the unalloyed XC10 steel. The results show a behavior which is similar to the one of T91 steel and suggest a common mechanism for liquid sodium embrittlement of body centered cubic steels. Moreover, they confirm that the ductile to brittle transition seems associated with a limited crack propagation rate. The propagation is thermally activated with activation energy of about 50 kJ/mol. Finally, it was shown that 304L austenitic steel is sensitive to liquid sodium embrittlement as well. Some fracture surfaces testify of an intergranular fracture mode, but some questions still remain about the crack path. (author)

  5. Oxygen influence on water chemistry and steel corrosion in its injection in the low temperature part of the condensate/feed train of NPS with a RBMK-1000 reactor

    International Nuclear Information System (INIS)

    Injection of gaseous oxygen in condensate reduces steel corrosion. However, the information is lacking on possible influence of oxygen on the corrosion of steels with different chrome content and water iron concentration in the low-temperature part of the condensate/feedwater train of NPS with a RBMK-1000 reactor. A 1600 h.test experiment was carried out at the Leningrad NPS with water oxygen concentration of 200 mg/kg, and conductivity not higher than 0.2 ms/cm. All the steels tested demonstrated the 10-fold reduction of corrosion and release of corrosion products into water. The 2.5% chrome alloying of steel results in strong reduction (in respect to steel 20) of corrosion product release. (author)

  6. Influence of Surface Modification on Properties of Stainless Steel Used for Implants / Wpływ Modyfikacji Powierzchni Na Właściwości Stali Nierdzewnej Stosowanej Na Implanty

    Directory of Open Access Journals (Sweden)

    Basiaga M.

    2015-12-01

    Full Text Available The aim of the study was assessment of the influence of stainless steel 316 LVM surface modification on its functional properties. The analyzed steel undergone a surface treatment consisting of the following processes: mechanical polishing, chemical passivation and deposition of Al2O3 layers by Atomic Layer Deposition method. The proposed variant of surface treatment will undoubtedly contribute to improving the functional properties of stainless steel intended for implants. In order to assess functional properties of the steel, electrochemical studies, adhesion (scratch test, wetting angle tests and topography of surface (AFM method were performed. The obtained results of the study showed clearly that the proposed by the authors way of surface treatment including: mechanical polishing, chemical passivation and deposition of Al2O3 layer by means of the ALD method effectively improves the corrosion resistance of stainless steel.

  7. Investigations Into the Influence of Weld Zone on Formability of Fiber Laser-Welded Advanced High Strength Steel

    Science.gov (United States)

    Bandyopadhyay, K.; Panda, S. K.; Saha, P.

    2014-04-01

    In this study, two different dual phase steel grades DP980 and DP600, and IFHS steel sheets were laser welded by a 2-kW fiber laser. The weld quality of these three different LWBs was assessed with the help of microstructure, micro-hardness and transverse tensile tests. Tensile testing of longitudinal and miniature samples was performed to evaluate the mechanical properties of the weld zone. Formability of parent materials and LWBs were assessed in bi-axial stretch forming condition by Erichsen cupping test. To validate the weld zone properties, 3-D finite element models of Erichsen cupping test of LWBs was developed, and the failures in the deformed cups were predicted using two theoretical forming limit diagrams. It was observed that hardness of the fusion zone and HAZ in laser welded DP600 and IFHS steels was more compared to the respective parent metal. However, 29% reduction in hardness was observed at the outer HAZ of DP980 steel weldments due to tempering of martensite. Reduction of formability was observed for all the LWBs with two distinct failure patterns, and the maximum reduction in formability was observed in the case of DP980 LWBs. The presence of the soft zone is detrimental in forming of welded DP steels.

  8. The influence of compressive stress applied by hard coatings on the power loss of grain oriented electrical steel sheet

    International Nuclear Information System (INIS)

    To reduce the core loss of electrical steel the vacuum arc ion plating technique has been used to deposit titanium nitride (TiN) layers on highly grain oriented electrical steel sheets. The layer thickness, the stresses of layers and coated sheets and the achieved reduction in core losses have been measured as functions of coating duration and applied bias voltage. Well adhered layers with high compressive stress up to 6.8 GPa have been produced. With increasing bias voltage the layer thickness decreases and the intrinsic stress of the layers increase. A further increase of bias voltage leads to a drop in stress due to thermal relaxation. In general, the tensile stress of the coated sheets rises with increasing layer thickness while the core loss of the coated material decreases with increasing tensile stress of the steel sheet and increasing bias voltage. The highest reduction of core loss has been found to be 28% (from P1.7=0.86 W/kg for commercially coated HGO electrical steel sheet with glass film to 0.62 W/kg for TiN coated material) and is due to the reduction of excess loss only. - Highlights: → Power loss of HGO electrical steel can be significantly reduced by tensile stress. → Tensile stress can be applied by hard coatings showing compressive stress like TiN. → The power loss can be decreased by 28%. → The reduction in loss is mainly due to the decrease of excess loss.

  9. Influence of Heat Treatment on the Microstructure and Corrosion Resistance of 13 Wt Pct Cr-Type Martensitic Stainless Steel

    Science.gov (United States)

    Lu, Si-Yuan; Yao, Ke-Fu; Chen, Yun-Bo; Wang, Miao-Hui; Ge, Xue-Yuan

    2015-12-01

    The effect of heat treatment on the microstructure and the electrochemical properties of a typical corrosion-resistant plastic mold steel in Cl--containing solution were studied in this research. Through X-ray diffraction patterns, SEM and TEM analysis, it was found that the sequence of the precipitates in the steels tempered at 573 K, 773 K, and 923 K (300 °C, 500 °C, and 650 °C) was θ-M3C carbides, nano-sized Cr-rich M23C6 carbides, and micro/submicron-sized Cr-rich M23C6 carbides, respectively. The results of the electrochemical experiments showed that the pitting potential of the as-quenched martensitic stainless steels increased with the austenitizing temperature. However, the corrosion resistance of the steels would decreased after tempering, especially when tempered at 773 K (500 °C), no passivation regime could be found in the polarization curve of the MSSs and no effective passive film could be formed on the steels in Cl--containing environments. The present results suggested that the temperature around 773 K (500 °C) should be avoided for tempering process of MSS used as plastic molds.

  10. Can the Point Defect Model Explain the Influence of Temperature and Anion Size on Pitting of Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Blackwood, Daniel J. [National University of Singapore, Singapore (Singapore)

    2015-12-15

    The pitting behaviours of 304L and 316L stainless steels were investigated at 3 °C to 90 °C in 1 M solutions of NaCl, NaBr and NaI by potentiodynamic polarization. The temperature dependences of the pitting potential varied according to the anion, being near linear in bromide but exponential in chloride. As a result, at low temperatures grades 304L and 316L steel are most susceptible to pitting by bromide ions, while at high temperatures both stainless steels were more susceptible to pitting by small chloride anions than the larger bromide and iodide. Thus, increasing temperature appears to favour attack by smaller anions. This paper will attempt to rationalise both of the above findings in terms of the point defect model. Initial findings are that qualitatively this approach can be reasonably successful, but not at the quantitative level, possibly due to insufficient data on the mechanical properties of thin passive films.

  11. INFLUENCE OF NaC1 DEPOSITION ON ATMOSPHERIC CORROSION OF A3 STEEL IN THE PRESENCE OF SO2

    Institute of Scientific and Technical Information of China (English)

    Q. Qu; C.W. Yan; L. Zhang; Y. Wan; C.N. Cao

    2002-01-01

    The regularities of atmospheric corrosion of A3 steel deposited with different amountof NaCl exposed to the air containing 1ppm SO2 at 80% RH and 25℃ were studied inlaboratory. NaCl can accelerate the corrosion of A3 steel obviously under such con-dition. The relationship between the weight loss of A3 steel and the amount of NaCldeposition can be well described by using a quadratic function. Fourier transform in-frared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopyand electron dispersion X-ray analysis (SEM/EDAX) were used to characterize thecorrosion products. In the absence of NaCl, FeSO4 xH2O is the dominant corro-sion products, while Fe3O4, FeSO4@ H2O, β-FeOOH and γ-FeOOH dominate in thepresence of NaCl.

  12. The influence of oxygen partial pressure on the kinetics of duplex scale formation on 316 stainless steel

    International Nuclear Information System (INIS)

    A previous study of iron tracer diffusion in duplex scale grown on vacuum annealed 316 steel had suggested that Fe cation diffusion was slower in the outer Fe3O4 layer than in the inner spinel. In order to obtain additional information on the location of the rate controlling step during duplex oxidation of 18 Cr-8 Ni type stainless steels, vacuum annealed 316 steel was oxidized at 6000C in atmospheres of controlled oxygen partial pressure covering the whole of the Fe3O4 stability range at that temperature. An oxygen partial pressure dependence of the primary parabolic rate of duplex scale formation of ksub(p) varies as Psub(O2)sup(0.135) was observed, providing further evidence that the rate controlling process is located in the outer Fe3O4 layer. (author)

  13. Influence of Cu and Ni on the morphology and composition of the rust layer of steels exposed to industrial environment

    Energy Technology Data Exchange (ETDEWEB)

    Ocampo C, L. M., E-mail: lmocampo@unalmed.edu.co [Universidad Nacional de Colombia, Facultad de Minas, Escuela de Ingenieria de Materiales (Colombia); Mattos, O. R., E-mail: hercilio@macbeth.if.usp.br [Federal University of Rio de Janeiro, EE/COPPE/PEMM (Brazil); Margarit-Mattos, I. C. P., E-mail: margarit@metalmat.ufrj.br [Federal University of Rio de Janeiro, Department of Inorganic Processes, School of Chemistry (Brazil); Fabris, J. D., E-mail: jdfabris@ufmg.br; Pereira, M. C., E-mail: mcpqui@ufmg.br [Federal University of Minas Gerais, Campus Pampulha, Department of Chemistry, ICEx (Brazil); Rechenberg, H. R., E-mail: hercilio@macbeth.if.usp.br [Institute of Physics, University of Sao Paulo (Brazil); Faria, D. L. A. de [Institute of Chemistry, University of Sao Paulo (Brazil)

    2006-01-15

    Four samples of steels with alloying elements were exposed to an industrial environment during 1,955 days, aiming to elucidate the effect of the alloying elements Cu and Ni on the resistance of weathering steels to corrosion processes. The samples were characterized with optical microscopy, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), saturation magnetization measurements and with energy dispersive (EDS), infrared, Moessbauer and Raman spectroscopies. All the steels originated orange and dark corrosion layers; their thicknesses were determined from the SEM images. EDS data of such rust layers showed that the alloying element content decreases from the steel core towards the outer part of the rust layer. Moreover, in the dark rust layer some light-gray regions were identified in the W and Cu-alloy steel, where relatively higher Cr and Cu contents were found. XRD patterns, infrared, Raman and Moessbauer spectra (298, 110 and 4 K) indicated that the corrosion products are qualitatively the same, containing lepidocrocite ({gamma}FeOOH; hereinafter, it may be referred to as simply L), goethite ({alpha}FeOOH; G), feroxyhite ({delta}'FeOOH; F), hematite ({alpha}Fe{sub 2}O{sub 3}; H) and magnetite (Fe{sub 3}O{sub 4}; M) in all samples; this composition does not depend upon the steel type, but their relative concentrations is related to the alloying element. Moessbauer data reveal the presence of (super)paramagnetic iron oxides in the corrosion products. Saturation magnetization measurements suggest that feroxyhite may be an occurring ferrimagnetic phase in the rust layer.

  14. The influence of martensitic transformation on mechanical properties of cast high alloyed CrMnNi-steel under various strain rates and temperatures

    International Nuclear Information System (INIS)

    Metastable austenitic steels show excellent mechanical properties, such as high strength combined with excellent ductility and toughness due to martensitic transformation under mechanical loading (transformation induced plasticity effect). A good energy consumption, and, in the case of high-alloyed metastable austenitic steels, a high corrosion resistance, increase the potential of these materials for diverse applications, also in regard of safety requirements. Up to now, numerous wrought alloys were investigated concerning mechanical behaviour, TRIP-effect, martensitic transformation behaviour and modelling of transformation kinetics or stress-strain behaviour. New high alloyed cast CrMnNi-steels, developed at Technical University Bergakademie Freiberg, provide the chance to reduce processing steps, production time and costs. In order to understand the influence of temperature on the martensitic phase transformation behaviour and therefore on mechanical properties and failure, the mechanical response under tensile loading in a temperature range between -700C and 2000C was investigated. The mechanical behaviour under compressive loading was also examined in a wide range of strain rates between 10-4 s-1 and 103 s-1 to obtain information about the strain rate effect on stress-strain behaviour and microstructural changes.

  15. Effect of the surface treatment on microbially influenced corrosion resistance of stainless steels; Taibiseibutsu fushokusei ni oyobosu stainless ko no hyomen shori no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Amaya, H.; Miyuki, H. [Sumitomo Metal Industries, Ltd., Osaka (Japan)

    1997-06-20

    This paper describes the corrosion potential ennoblement behavior of stainless steel with various surface treatments and the effects of surface treatment on the microbially influenced corrosion (MIC) by means of simulated MIC reproduction test method in the laboratory. SUS316L steels were polished, passivated, electropolished, and electrolyzed in Fe(III)Cr(VI) containing solution and in sulfuric acid. For the specimens polished, passivated, electropolished and electrolyzed in sulfuric acid, the corrosion potential was ennobled in the MIC test solution, and crevice corrosion was generated in the seawater. For the specimen electrolyzed in Fe(III)Cr(VI) containing solution, the corrosion potential was ennobled only in a degree of standard electrode, and crevice corrosion was not observed. The film on the steel surface had a double layer structure composing of the Fe hydride outer layer and the Cr oxide inner layer. The cathodic polarization reaction of the bipolar membrane, which consisted of outer anion selective layer and inner cation selective layer, was suppressed. The corrosion potential ennoblement due to the promotion of cathodic polarization reaction by bacteria was suppressed. Thus, excellent anti-MIC property was demonstrated. 17 refs., 11 figs., 5 tabs.

  16. Influence of a doping by Al stainless steel on kinetics and character of interaction with the metallic nuclear fuel

    Science.gov (United States)

    Nikitin, S. N.; Shornikov, D. P.; Tarasov, B. A.; Baranov, V. G.

    2016-04-01

    Metallic nuclear fuel is a perspective kind of fuel for fast reactors. In this paper we conducted a study of the interaction between uranium-molybdenum alloy and ferritic- martensitic steels with additions of aluminum at a temperature of 700 ° C for 25 hours. The rate constants of the interaction layer growth at 700 °C is about 2.8.10-14 m2/s. It is established that doping Al stainless steel leads to decrease in interaction with uranium-molybdenum alloys. The phase composition of the interaction layer is determined.

  17. CHANGE OF CONNECTION BETWEEN MAGNETIC PARAMETERS OF CAST IRON IN COMPARISON WITH STEEL UNDER INFLUENCE OF INTERNAL DEMAGNETIZATION

    Directory of Open Access Journals (Sweden)

    S. G. Sandomirsky

    2014-01-01

    Full Text Available Connection of maximum magnetic permeability µm of cast irons with coercive force Нс and residual magnetism Мr is established in all size of changing of the magnetic characteristics of cast iron. Differences of this connection for steels and cast irons are revealed. Formula for calculation µm of steels by Нс and Мr is corrected for calculation µm of cast irons. As a result of correction the calculation error of cast irons µm is diminished. The results can be used in magnetic structural analysis instead of labor-consuming measurement µm.

  18. The influence of reinforcing particles on mechanical and tribological properties and microstructure of the steel-TiB2 composites

    OpenAIRE

    I. Sulima; L. Jaworska; P. Wyżga; M. Perek-Nowak

    2011-01-01

    Purpose: The present work aims to investigate the effect of the reinforcing ceramic particles on the mechanical and tribological properties and microstructure of the steel-TiB2 composites.Design/methodology/approach: The austenitic AISI316L stainless steel reinforced with 10 vol.% and 20 vol.% TiB2 particles was produced using the high temperature-high pressure (HT-HP) method. The sintering process was carried out at pressure of 7.0±0.2 GPa and temperature of 1200°C for 60 seconds. Density of...

  19. Influence of temperature of test on the mechanical properties for rail wheel steel with new system of alloyage

    OpenAIRE

    Babachenko, A. I.; Kononenko, A A; Knysh, А. V.; Dement′eva, Zh. A.; Shpak, E. A.; Klinovaya, О. F.

    2016-01-01

    Purpose.  Comparative studies of the mechanical properties of steels at different temperatures for testing of railway wheels of different chemical composition. Methods. Pull test at stretching by high temperatures at GOST 9651, test the percussion bend at low temperatures were made according at GOST 9454 specimen taken from the rims of solid-rolled railway wheels of steel “2”, “T” and “K”, manufacture of PJSC “Interpipe NTRP". Results. Increasing temperature pull test results in reduced stren...

  20. The effect of pre-oxidation and the influence of deformation on the corrosion behaviour of two heat resistant steels in a sulphur-oxygen-carbon bearing environment

    International Nuclear Information System (INIS)

    The influence of pre-oxidation on the corrosion resistance of the austenitic steels AC 66 (Fe-32Ni-27Cr-0.07Ce) and alloy 800H (Fe-32Ni-20Cr) was studied in a sulphur-oxygen-carbon bearing atmospheric at 700oC. For AC 66 the corrosion resistance was significantly improved by preoxidation, whereas this effect was less marked for Alloy 800H. This can be explained by a much better adherence of the preformed oxide scale for AC 66. The corrosion resistance was shown to decrease by superimposed deformation which leads to deeply penetrating intergranular corrosion paths. (Author)

  1. Influence of the feed rate and the lateral beam displacement on the joining quality of laser-welded copper-stainless steel connections

    Science.gov (United States)

    Weigl, M.; Schmidt, M.

    The present article deals with the laser-welding of copper and stainless steel connections for applications in power electronics. Here, the particular demand for such dissimilar connections is caused by the increasing implementation of electronics in areas with contact to corrosive fluids, which copper cannot resist. In this context the influence of a lateral displacement of the laser beam and the feed rate on the metallurgical properties of the dissimilar materials' connection is highlighted. The effects of these parameters are discussed on the base of metallographic specimen, micro-hardness measurements and element analysis.

  2. The Influence of Calcined Clay Pozzolan, Low-Cao Steel Slag and Granite Dust On the Alkali-Silica Reaction in Concrete

    OpenAIRE

    James Sarfo-Ansah; Eugene Atiemo

    2015-01-01

    The influence of low CaO steel slag, calcined clay and granite dust on the alkali-silica reaction was investigated over a period of 35 days under accelerated curing conditions. The mineral admixtures were used to replace varying portions of high alkali Portland limestone cement up to an admixture content of 25% in order to study their effect on the alkali-silica reaction (ASR). Portland limestone cement used for the study had a total Na2Oeq of 4.32. XRD analysis of hydrated mortar...

  3. Vpliv meje tečenja in temperature na odpornostne krivulje J-R jekel s povišano trdnostjo: Influence of yield strength and temperature on J-R resistance curves of HSLA steels:

    OpenAIRE

    Legat, Janko; Vojvodič-Tuma, Jelena; Gubeljak, Nenad

    1998-01-01

    The aim of this research program was to study the influence of yield strength and temperature on the ductile crack growth resistance (J-R resistance curves) of a common construction steel and three HSLA (high strength low alloy) steels. Three different material conditions were observed: normalized condition (as-delivered), deformed state and aged state. The experiments were carried out on standard CT specimens at room temperature and at the temperature of nonductile tearing. The unloading com...

  4. Influence of Different Surface Treatments of H13 Hot Work Die Steel on Its Thermal Fatigue Behaviors

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Thermal fatigue checking is the general failure of hot work die steels, which is relative with the structures and properties of the steels and the stress alternated during the employment. The Uddeholm test method on thermal fatigue is used to compare the behaviors of different samples, which are treated with plasma nitriding、plasma sulfur-carbon-nitriding、 boronizing or not treated. The results show that the nitriding improves the thermal fatigue property of the tool steel, while the plasma sulfur-carbon-nitriding and the boronizing impair the property. The mechanisms are induced as follows. By increasing the hardness and changing the stress distribution in the surface layer, surface treatment can decrease the plastic deformation and the tensile stress during the cycling. Therefore,the generation and growth of the cracks are restrained. On the other hand, as results of surface treating, in the surface layer the toughness declines and the expanding coefficient ascendes; the latter change caused the strengthening of the tensile and compressive stress during the cycling. Thus the resistance to thermal fatigue is weakened. Whether or not the surface treatment is favor to thermal fatigue of tool steels relies on which factor is dominant.

  5. Influence of hot rolling and high speed hydrostatic extrusion on the microstructure and mechanical properties of RAF ODS steel

    International Nuclear Information System (INIS)

    Argon gas atomized, pre-alloyed Fe-14Cr-2W-0.3Ti oxide dispersion strengthened (ODS) ferritic steel powder was mechanically alloyed with 0.3Y2O3 (wt.%) nano-particles in attritor ball mill and consolidated by hot isostatic pressing (HIP) at 1150 deg. C under pressure of 200 MPa for 3 hrs. To improve mechanical properties of as HIPped ODS ingots the material was undergone further thermo-mechanical treatment (TMT), namely: hot rolling (HR) at 850 deg. C or high speed hot extrusion (HSHE) at 850 deg. C. After TMT both materials were annealed at 1050 deg. C for 1 h in vacuum. Transmission electron microscopy (TEM) observations of the ODS alloys after TMT and heat treatment exhibited elongated in a longitudinal direction grains with an average size of 75 μm. However, an equiaxed, smaller than 500 nm grains were also found in the microstructure of both materials. Different size and morphology of oxides particles were also observed. Bigger, about 150 nm Ti-Al-O particles were usually located at grain boundaries whereas Y-Ti-O nanoclusters of about 5 nm were uniformly distributed in ODS steel matrix. The Charpy impact tests revealed significantly better about 90% (5.8 J) upper shelf energy (USE) of material after HSHE but ductile to brittle transition temperature (DBTT) of both alloys was unsatisfactory. As-HR ODS steel has shown DBTT of about 55 deg. C whereas HSHE ODS steel has about 75 deg. C. This relatively high values of transition temperature were probably caused by oxides particles present at grain boundaries of the ODS alloys which decreased fracture properties of the ODS steels. High temperature tensile properties of both ODS alloys are found to be satisfactory in full range of the testing temperature from 23 up to 750 deg. C. However, about 15% better UTS and YS0.2 (1350 MPa and 1285 MPa, respectively) as well as ductility were measured in the case of the as-HSHE ODS steel. These results indicates that HSHE process of the ODS steel can be considered as more

  6. Nuclear transmutation in steels

    Science.gov (United States)

    Belozerova, A. R.; Shimanskii, G. A.; Belozerov, S. V.

    2009-05-01

    The investigations of the effects of nuclear transmutation in steels that are widely used in nuclear power and research reactors and in steels that are planned for the application in thermonuclear fusion plants, which are employed under the conditions of a prolonged action of neutron irradiation with different spectra, made it possible to study the effects of changes in the isotopic and chemical composition on the tendency of changes in the structural stability of these steels. For the computations of nuclear transmutation in steels, we used a program complex we have previously developed on the basis of algorithms for constructing branched block-type diagrams of nuclide transformations and for locally and globally optimizing these diagrams with the purpose of minimizing systematic errors in the calculation of nuclear transmutation. The dependences obtained were applied onto a Schaeffler diagram for steels used for structural elements of reactors. For the irradiation in fission reactors, we observed only a weak influence of the effects of nuclear transmutation in steels on their structural stability. On the contrary, in the case of irradiation with fusion neutrons, a strong influence of the effects of nuclear transmutation in steels on their structural stability has been noted.

  7. The influence of low-strain thermo-mechanical processing on grain boundary network characteristics in type 304 austenitic stainless steel.

    Science.gov (United States)

    Engelberg, D L; Humphreys, F J; Marrow, T J

    2008-06-01

    Grain boundary engineering of austenitic stainless steel, through the introduction of plastic strain and thermal annealing, can be used to develop microstructures with improved resistance to inter-granular degradation. The influence of low-strain thermo-mechanical processing on grain boundary network development, with systematic variations of annealing treatments, has been investigated. Three stages of the microstructure development during grain boundary engineering in low-strain processing conditions are identified, and correlated with changes in grain boundary character and deviation distributions. Low-energy connected length segments at triple junctions, which have been proposed to be responsible for crack bridging during inter-granular stress corrosion cracking, can be influenced by the choice of the annealing treatment parameters. The development of individual grain boundary length segments of different character showed consistent trends with increasing grain size. Crack length predictions are consistent with the beneficial effect of designing microstructures with high fractions of twin grain boundaries and smaller grain size. PMID:18503670

  8. Influence of the Surface Layer when the CMT Process Is Used for Welding Steel Sheets Treated by Nitrooxidation

    Directory of Open Access Journals (Sweden)

    I. Michalec

    2012-01-01

    Full Text Available Nitrooxidation is a non-conventional surface treatment method that can provide significantly improved mechanical properties as well as corrosion resistance. However, the surface layer is a major problem during the welding process, and welding specialists face many problems regarding the weldability of steel sheets. This paper deals with the properties of a nitrooxidized surface layer, and evaluates ways of welding steel sheets treated by nitrooxidation using a Cold Metal Transfer (CMT process. The limited heat input and the controlled metal transfer, which are considered as the main advantage of the CMT process, have a negative impact on weld joint quality. An excessive amount of porosity is observed,probably due to the high content of nitrogen and oxygen in the surface layer of the material and the fast cooling rate of the weld pool.

  9. Bauschinger Effect in Microalloyed Steels: Part II. Influence of Work Softening on Strength Development During UOE Line-Pipe Forming

    Science.gov (United States)

    Kostryzhev, Andrii G.; Strangwood, Martin; Davis, Claire L.

    2011-10-01

    The Bauschinger effect (a reduced yield stress at the start of reverse deformation following forward prestrain) is an important factor of strength development for cold metal forming technology. In steels, the magnitude of the Bauschinger effect depends on composition, through the presence of microalloy precipitates, and prior processing, through the size and distribution of the microalloy precipitates and the presence of retained work hardening. In this article, the parameters of the Bauschinger effect and work hardening (coefficient and exponent) in forward and reverse deformations were quantitatively related to the particle number density and dislocation density for two high-strength low-alloy (HSLA) steels. An example of the application of the obtained dependences is discussed with respect to the strength development during UOE forming of large diameter line pipes.

  10. Influence of sulphur content and inclusion distribution on the hydrogen induced blister cracking in pressure vessel and pipeline steels

    Energy Technology Data Exchange (ETDEWEB)

    Domizzi, G.; Anteri, G.; Ovejero-Garcia, J. [Comision de Energia Atomica, Beunos Aires (Argentina). Depto. Materiales Gerencia Desarollo

    2001-07-01

    In previous works, extensive desulphurisation, including shape control and low hardness in segregation zones, were pointed out as effective ways for increasing resistance to hydrogen induced cracking (HIC) in steels exposed to wet H{sub 2}S environment. In this study, the behaviour of eight plates was evaluated by immersing samples in H{sub 2}S-saturated NACE solution. HIC susceptibility was assessed by an ultrasonic method and correlated with the elongated MnS inclusion distribution. The results allow us to remark that an extremely low sulphur level is not necessary to reach good HIC resistance, provided that no hard bands are present in the steel. Under this condition, a relationship to calculate the minimum average sulphide length which provides low HIC susceptibility was found. (author)

  11. The Influence Of Load History On Durability Of P92 Steel Used For The Construction Of Energy Pipelines

    Directory of Open Access Journals (Sweden)

    Cieśla M.

    2015-09-01

    Full Text Available The research material used in the study was the martensitic creep-resistant steel P92 used for the manufacture of pipes being part of power generation units subject to heavy load. The research problem focused on two issues. The first one was to analyze how the plastic deformation cumulated in the material in low-cycle fatigue conditions affects the characteristics of the material in creep conditions in a temperature of 600ºC. The other one was concerned with analysis of a reverse situation, i.e. how the initial plastic deformation of the material in creep conditions changes the mechanical characteristics of the steel under low-cycle fatigue conditions in a temperature of 600ºC.

  12. Influence of / ratio on rate of chloride induced corrosion of steel reinforcement and its dependence on ambient temperature

    Indian Academy of Sciences (India)

    V Živica

    2003-08-01

    The permeability of the embedding cement material for the rate of chloride induced corrosion when the ambient temperature is increased has found a dominant position. The importance of the given permeability in the process is based on the fact that it represents a factor conditioning the possibility of the escaping of the unambiguous reaction partners, oxygen and water vapour, from the system embedding cement material-steel, as the ambient temperature is increased. The resulting effect is a slowing down of the corrosion rate when the / ratio over the value 0.6 and the ambient temperature over the value 40°C are increased. Due to the similarity of the chemism of the corrosion process of steel reinforcement, independent of the action of aggressive species, the found relationships are generally valid, e.g. for the corrosion due to carbonation.

  13. Influence of the austenite-martensite transformation in the dimensional stability of a new tool steel alloyed with niobium (0.08% wt.) and vanadium (0.12% wt.)

    International Nuclear Information System (INIS)

    Austenite-martensite transformation influence on the dimensional stability of a new experimental tool steel alloyed with niobium (0.08% wt.) and vanadium (0.12% wt.) has been studied. The dimensional stability of this new steel was compared with the dimensional stability of commercial steel, after and before two thermal treatments, T1 (860 degree centigrade) and T2 (900 degree centigrade). The thermal treatments consisted on heating and cooling, at 1 atmosphere of pressure, in N2 atmosphere furnace, following by heating in a conventional furnace at 180 degree centigrade during 1 hour. Initially, the experimental steel composition and Ac1 and Ac3 transformation temperatures were determined by glow-discharge luminescence (GDL) and dilatometric tests, respectively, in order to select the austenization temperatures of T1 and T2 treatments. After hardness measurement, the microstructure of both steels was characterized by X-Ray Diffraction (XRD) and optical metallography, before and after of T1 and T2 thermal treatments. Finally, longitudinal and angular dimensional stability analyses were realized for both commercial and experimental steels. After a contrastive hypothesis analysis, the results showed that the longitudinal relative variation of the experimental steel calculated was around 0.2% and the angular relative variation was not significant. (Author)

  14. The influence of fibre orientation on the post-cracking tensile behaviour of steel fibre reinforced self-compacting concrete

    OpenAIRE

    A. Abrishambaf; V.M.C.F. Cunha; Barros, J. A. O

    2015-01-01

    Adding fibres to concrete provides several advantages, especially in terms of controlling the crack opening width and propagation after the cracking onset. However, distribution and orientation of the fibres toward the active crack plane are significantly important in order to maximize its benefits. Therefore, in this study, the effect of the fibre distribution and orientation on the post-cracking tensile behaviour of the steel fibre reinforced self-compacting concrete (SFRSCC) specimens is i...

  15. Influence of Subsurface Layers on Goss-Texture Development in Secondary Recrystallization of RGO Electrical Steel Sheet

    OpenAIRE

    Börttcher, A.; Hastenrath, M.; Lücke, K.

    1991-01-01

    Regular grain oriented (RGO) electrical steel sheet used for power transformer cores is produced by a two stage cold rolling process with intermediate annealing and a subsequent decarburizing primary recrystallization. Its beneficial magnetic properties originate from a sharp Goss-texture developed by the following secondary recrystallization. By controlled thinning of the material the sharpness of this Goss-texture will be shown to strongly depend on texture and structure of the subsurface l...

  16. Influence of Ferrite Content on Fatigue Strength of Quenched and Tempered 42CrMoS4 Steel

    OpenAIRE

    Hanno, Mithaq Elias

    2012-01-01

    Specimens of steel 42CrMoS4 were quenched from the austenite (γ) and the ferrite (α) + austenite + cementite phase fields to produce fully martensitic matrices with 0 – 14 % ferrite dispersed in the matrix. After tempering at 300°C or 600°C mechanical and fatigue properties were determined. As expected yield strength, tensile strength and hardness decreased with increased tempering temperature and ferrite content. Quite unexpected, the fatigue properties were mildly affected. A small amount o...

  17. The Influence of Shielding Gas and Heat Input on the Mechanical Properties of Laser Welds in Ferritic Stainless Steel

    Science.gov (United States)

    Keskitalo, M.; Sundqvist, J.; Mäntyjärvi, K.; Powell, J.; Kaplan, A. F. H.

    Laser welding of ferritic steel in normal atmosphere gives rise to weld embrittlement and poor formability. This paper demonstrates that the addition of an argon gas shield to the welding process results in tough, formable welds. Post weld heat treatment and microscopic analysis has suggested that the poor ductility of welds produced without a gas shield is, to some extent, the result of the presence of oxides in the weld metal.

  18. Use of an Electrochemical Split Cell Technique to Evaluate the Influence of Shewanella oneidensis Activities on Corrosion of Carbon Steel.

    Science.gov (United States)

    Miller, Robert Bertram; Sadek, Anwar; Rodriguez, Alvaro; Iannuzzi, Mariano; Giai, Carla; Senko, John M; Monty, Chelsea N

    2016-01-01

    Microbially induced corrosion (MIC) is a complex problem that affects various industries. Several techniques have been developed to monitor corrosion and elucidate corrosion mechanisms, including microbiological processes that induce metal deterioration. We used zero resistance ammetry (ZRA) in a split chamber configuration to evaluate the effects of the facultatively anaerobic Fe(III) reducing bacterium Shewanella oneidensis MR-1 on the corrosion of UNS G10180 carbon steel. We show that activities of S. oneidensis inhibit corrosion of steel with which that organism has direct contact. However, when a carbon steel coupon in contact with S. oneidensis was electrically connected to a second coupon that was free of biofilm (in separate chambers of the split chamber assembly), ZRA-based measurements indicated that current moved from the S. oneidensis-containing chamber to the cell-free chamber. This electron transfer enhanced the O2 reduction reaction on the coupon deployed in the cell free chamber, and consequently, enhanced oxidation and corrosion of that electrode. Our results illustrate a novel mechanism for MIC in cases where metal surfaces are heterogeneously covered by biofilms.

  19. Influence of hydroxyis, carbonates and chiorides ions on the pitting corrosión of steel in concrete

    Directory of Open Access Journals (Sweden)

    Chaussadent, Thierry

    1992-06-01

    Full Text Available The electrochemical process of steel corrosion in concrete are studied by simulating its liquid phase with synthetical solutions in a large range of hydroxyls, carbonates and chlorides ions.The steel specimen is either under or without an electrical polarization. The present analysis has made it possible to define a new relevant parameter, which is the [CΓ]/[AIK] ratio (where AIK is the total alkalinity. It characterizes the conditions of the polarized steel pitting corrosion. Furthermore, the investigation showed out that a polarization at potentials lower than — 700 mVSCE, stops the corrosion processes.

    Los procesos electroquímicos de corrosión de las armaduras de acero del hormigón son estudiados simulando su fase líquida mediante disoluciones sintéticas que cubren playas importantes en iones hidróxilos, carbonates y cloruros. El acero está sometido o no a una polarización eléctrica. Este análisis ha permitido definir un nuevo parámetro significativo, la relación [CΓ]/[AIK] (siendo AIK la alcalinidad total, que caracteriza las condiciones de corrosión por picaduras del acero polarizado. Además, el estudio ha mostrado que una polarización, a un potencial más bajo que — 700 mVSCE impide los mecanismos de corrosión.

  20. Nanosecond laser surface modification of AISI 304L stainless steel: Influence the beam overlap on pitting corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Pacquentin, Wilfried, E-mail: wilfried.pacquentin@cea.fr [CEA, DEN/DANS/DPC/SEARS/LISL, F-91191 Gif-sur-Yvette (France); Caron, Nadège [CEA, DEN/DANS/DPC/SEARS/LISL, F-91191 Gif-sur-Yvette (France); Oltra, Roland [Laboratoire Interdisciplinaire Carnot de Bourgogne, Université de Bourgogne, UMR CNRS 5209, 21078 Dijon Cedex (France)

    2014-01-01

    Surface modifications of AISI 304L stainless steel by laser surface melting (LSM) were investigated using a nanosecond pulsed laser-fibre doped by ytterbium at different overlaps. The objective was to study the change in the corrosion properties induced by the treatment of the outer-surface of the stainless steel without modification of the bulk material. Different analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and glow discharge optical emission spectrometry (GDOES) were used to characterize the laser-melted surface. The corrosion resistance was evaluated in a chloride solution at room temperature by electrochemical tests. The results showed that the crystallographic structure, the chemical composition, the properties of the induced oxide layer and consequently the pitting corrosion resistance strongly depend on the overlap rate. The most efficient laser parameters led to an increase of the pitting potential by more than 300 mV, corresponding to a quite important improvement of the corrosion resistance. This latter was correlated to chromium enrichment (47 wt.%) at the surface of the stainless steel and the induced absence of martensite and ferrite phases. However, these structural and chemical modifications were not sufficient to explain the change in corrosion behaviour: defects and adhesion of the surface oxide layer must have been taken into consideration.