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Sample records for 16mnd5 steel influence

  1. Microstructural influence on the local behaviour of 16MND5 steel

    16MND5 Steel or A508 Cl3 is used for manufacture by forging of nuclear reactor vessels. This material presents a good compromise in term of tenacity and yield stress, its microstructure is mainly bainitic tempered. Because of the chemical composition local variation and process of development, this material presents microstructural heterogeneities which can locally modify the properties of damage. In particular, some zones present a martensitic microstructure. The goal of this thesis is to bring some explanations on the influence of the microstructure; more particularly, size of the crystallographic entities and their spatial distribution on the local behaviour of 16MND5 steel. Two microstructures were elaborated for this purpose, a tempered bainitic microstructure and a tempered martensitic microstructure. An experimental characterization was carried out on the two microstructures in order to determine morphology, spatial distribution of the crystallographic orientations and tensile behaviour. A deposit of micro grid was carried out on tensile specimens to determine the experimental deformation field on a beforehand EBSD analyzed zone. The determination of the tensile behaviour allowed the identification of a multi crystalline behaviour law by a reverse method using the density of dislocation on each system of slip. This behaviour law was used in simulations with a finite element method to simulate the local mechanical field of the two microstructures and to compare with the obtained experimental deformation fields. It results, a good adequacy between simulations and experiments and the description of the influence of the neighbor grain's orientation on the local behaviour. (author)

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

    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

  3. A micro-mechanical analysis and an experimental characterisation of the behavior and the damaging processes of a 16MND5 pressure vessel steel at low temperature

    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 {100} 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)

  4. 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

    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)

  5. Dislocation structures in 16MND5 pressure vessel steel strained in uniaxial tension at -196 °C

    Obrtlík, Karel; Robertson, Christian; Marini, Bernard

    96 2005, č. 8 (2005), s. 909-912. ISSN 0044-3093 R&D Projects: GA AV ČR(CZ) 1QS200410502 Keywords : Bainitic steel * Dislocation structure * Tension test Subject RIV: JG - Metallurgy Impact factor: 0.842, year: 2005

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

    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)

  7. 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

    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)

  8. Experimental study and simulation of transformation induced plasticity, and multiphase behaviour of the 16MND5 vessel steel under aniso-thermal multiaxial loading

    This work deals with the aniso-thermal multiphase behaviour of the French vessel steel and more specially about the transformation plasticity in the cases of multiaxial non-proportional loadings paths. The first part of this report is devoted to the presentation of a high temperature tension-torsion experimental device enable of obtaining a large range of cooling rate. This experimental set-up is used to explore the transformation plasticity under proportional or non-proportional loading paths, during austenitic, bainitic and martensitic transformations. The results of the tests are compared to the Leblond's model. In the last part, we propose a two-scale behaviour model in which the type of each phase behaviour can be different. This meso-model is finally used to simulate two real tests on structures. (author)

  9. 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

    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

  10. Microbially Influenced Corrosion of Stainless Steels

    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.

  11. Microbially influenced corrosion of carbon steels

    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.

  12. Formation mechanism of solute clusters under neutron irradiation in ferritic model alloys and in a reactor pressure vessel steel: clusters of defects

    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)

  13. FACTORS INFLUENCING THE WEAR BEHAVIOR OF PM STEELS

    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.``

  14. 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

    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)

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

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

    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

  17. The influence of tool steel microstructure on galling

    Karlsson, Patrik

    2014-01-01

    In sheet metal forming (SMF) of materials such as stainless steels there is a major problem with transfer and accumulation of sheet material to the metal forming tool surface. The problem is known as galling; a sort of severe adhesive wear, which results in severe scratching of produced parts. In this thesis, the overall aim was to gain knowledge of the influence of tool steel microstructure on galling initiation under sliding conditions. It was discovered that material transfer and tool stee...

  18. Monitoring Techniques for Microbially Influenced Corrosion of Carbon Steel

    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...... carbon steel must be monitored on-line in order to provide an efficient protection and control the corrosion. A number of monitoring techniques is industrially used today, and the applicability and reliability of these for monitoring MIC is evaluated. Coupons and ER are recommended as necessary basic...... techniques even though localised corrosion rate cannot be measured. FSM measures general corrosion and detects localised corrosion, but the sensitivity is not high enough for monitoring initiation of pitting and small attacks. Electrochemical techniques as LPR and EIS give distorted data and unreliable...

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

    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. Microbially influenced corrosion of stainless steels in nuclear power plants

    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.

  1. Monitoring Techniques for Microbially Influenced Corrosion of Carbon Steel

    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 and...... control the corrosion. A number of monitoring techniques is industrially used today, and the applicability and reliability of these for monitoring MIC is evaluated. Coupons and ER are recommended as necessary basic techniques even though localised corrosion rate cannot be measured. FSM measures general...... corrosion and detects localised corrosion, but the sensitivity is not high enough for monitoring initiation of pitting and small attacks. Electrochemical techniques as LPR and EIS give distorted data and unreliable corrosion rates, when biofilm and corrosion products cover the steel surface. However, EIS...

  2. Influence of HIP treatment on aluminised ferritic-martensitic steels

    Coatings on low activation steels are required in fusion technology in order to reduce the tritium permeation rate through the steel into the cooling water system by a factor of at least 100. Alumina seems to be a promising coating material. However, an appropriate coating system must also have the potential for self healing since the ceramic alumina scale tends to fail if mechanical stress is applied. Hot-dip aluminising is an applicable technology to coat ferritic-martensitic steels which consists of two main process steps: firstly, hot dip aluminising of the steel (700 C, 30 s) Secondly, transformation of the very hard intermetallic scale Fe2Al5 into FeAl and α-Fe(Al) phase during a subsequent heat treatment (1040 C, 30 min). The pressure chosen for the HIP experiment was 1000, 2000 and 3000 bar. Compared to a heat treatment without superimposed high pressure pores formation due to the Kirkendall effect could be suppressed successfully. The influence of the high pressure on the heat treatment (1040 C, 30 min) will be discussed in this paper. (orig.)

  3. Anticorrosive Influence of Acetobacter aceti Biofilms on Carbon Steel

    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.

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

    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.

  5. Factors influencing the surface quality of polished tool steels

    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)

  6. INFLUENCE OF ELECTRIC SPARK ON HARDNESS OF CARBON STEEL

    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

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

    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

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

    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.

  9. Alloys influence in ferritic steels with hydrogen attack

    Materials exposed to a corrosive environment and high temperatures, are associated with a decrease of their mechanical properties and embitterment.At room temperatures atomic hydrogen diffuses easily through metals structure, it accumulates in lattice defects forming molecular hydrogen and generating cracking due to internal stresses.Under high temperatures the phenomenon is more complex.The steels in these conditions present different structures of precipitates, that the change under creep conditions period.In this work it is determined the influence of Cr and V alloys, the changes of ferritic steel resistance in a corrosive environment and high temperatures.1.25 Cr 1 Mo 0.25 V and 2.25Cr 1 Mo under different loads and temperatures previously attacked by hydrogen environment.The hydrogen is induced by the electrolytic technique, optimizing the choice of temperatures, current density, electrolyte, etc. In order to control an adequate cathode charge, a follow up procedure is carried out by electronic barrier microscopy.After the attack, the material is settled at room temperatures for certain period of time, to allow the hydrogen to leave and evaluate the residual damage.Creep by torsion assays, under constant load and temperature is used as an experimental technique.With the outcome data curves are drawn in order to study the secondary creep rate, with the applied load and temperature, determining the value of stress exponent n and the activation energy Q.Comparing to equal assays to the same ferritic steels but non attacked by hydrogen, these values allows the prediction of microstructure changes present during these tests

  10. Influence of mean stress on fatigue strength of stainless steel

    In order to incorporate the mean stress effect in the design fatigue curve for designing nuclear power plant components, change in fatigue strength due to the mean stress and root causes of the change were investigated for Type 316 stainless steel. First, 20% cold work was applied to specimens of Type 316 stainless steel in order to reduce the cyclic strain hardening and softening during fatigue tests, and then, the specimens were subjected to stress controlled fatigue tests under the mean stress in air at room temperature. Although the mean stress tended to show a beneficial effect on the fatigue life under the same stress amplitude, it had a detrimental effect under the same strain range. It was shown that the reduction in fatigue life was brought about by the change in the effective strain, which was caused not only by the rise in the crack opening point but also by ratcheting deformation during the fatigue tests. The mean stress had little influence on the fatigue limit for the strain range. It was concluded that, although the mean stress reduced the fatigue life in the stress controlled fatigue tests, its effect did not need to be considered in the design fatigue curve because no significant change in the effective strain range occur in actual components. (author)

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

    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.)

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

    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.)

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

    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.

  14. Influence of the Zr and Ce on the structure of experimental hot-work tool steel

    L.A. Dobrzański; J. Mazurkiewicz; E. Hajduczek

    2006-01-01

    Purpose: of this paper was to examine of the influence of the Zr i Ce on the structure of the newly developed complex hot-work tool steel 47CrMoWVTiCeZr16-26-8 in relation to standard hot-work tool steel X40CrMoV5-1.Design/methodology/approach: The investigations steels were made using the specimens made from the experimental steel, for which the working 47CrMoWVTiCeZr16-26-8 denotation was adopted, similar to the ones used in the ISO Standard on using the standard alloy hot-work tool steel X...

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

    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.)

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

    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.

  17. Influence of titanium on the tempering structure of austenitic steels

    The microstructure of titanium-stabilized and initially deformed (approximately 20%) austenitic stainless steels used in structures of fast neutrons reactors has been studied after one hour duration annealings (500 0C) by X-ray diffraction, optical microscopy, microhardness and transmission electron microscopy. The studied alloys were either of industrial type CND 17-13 (0.23 to 0.45 wt% Ti) or pure steels (18% Cr, 14% Ni, 0 or 0.3 wt% Ti). During tempering, the pure steels presented some restauration before recristallization. In the industrial steels, only recristallization occurred, and this only in the most deformed steel. Precipitation does not occur in the titanium-free pure steel. In industrial steels, many intermetallic phases are formed when recristallization starts

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

    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.

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

    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.

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

    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...

  1. Influence of stress on passive behaviour of steel bars in concrete pore solution

    Research highlights: → The influence of load on passivity of steel in concrete pore solution is studied. → The passivity of steel in pore solution decreased as the load amplitude increased. → A micro-crack model is presented to explain passive behaviour of steel under loads. - Abstract: The influence of stress on passive behaviour of steel bars in concrete pore solution was studied with electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The passive ability of steel decreased as the applied load increased and higher load had much greater influence on passivation than repeated loading of small magnitude. A micro-crack model was presented to explain the damage of passive layer by loads. Lower load caused micro-cracks in the passive film which might be completely recovered after unloading. Under higher load more micro-cracks were produced in the passive film and some may penetrate the film, leading to irreversible damages.

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

    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.

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

    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

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

    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.

  5. Influence of carbide precipitation upon hydrogen fragilization of an AISI 304 steel

    The present work deals with austenitic stainless steels for a family of steels that is renowned for its high resistance to hydrogen fragilization. Nevertheless, these steels may suffer hydrogen fragilization under severe working conditions. This fact is strongly dependent on many factors -composition, grain size, other phases present, corrosion sensitivity, etc.-. While there are studies that show how intergranular corrosion is influenced by corrosion sensitivity -mainly due to carbide precipitation in grain boundaries-, there are no reports about the effect of the carbide precipitation itself on hydrogen fragilization for these steels. (Author)

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

    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)

  7. Influence of the impurities on the depth of penetration with carbon steel weldings

    O. Savytsky

    2014-04-01

    Full Text Available In this paper the results of the research about the influence of the impurities on the depth of penetration with carbon steels weldings of different chemical composition are presented. These data suggest that presence of those impurities, such as sulphure and oxygen, in the steel, increases the depth of penetration to 1,3 - 1,5 times compared to welding refined steels. Applying activating fluxes for welding high tensile steels, provides an increase in the depth of penetration of 2 - 3 times.

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

    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)

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

    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.

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

    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.

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

    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.

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

    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

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

    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

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

    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.

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

    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)

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

    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.

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

    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.

  18. THE INFLUENCE OF THE INCREASE RATE OF TEMPERATURE SURFACE OF STEEL CHARGE ON CO2 EMISSION

    Kieloch, Marian; Boryca, Jaroslav

    2011-01-01

    CO2 emission is one of the factors, which in addition to the consumption of thermal energy and the loss of steel by oxidation also affect the costs of heating process in a reheating furnace. The analysis of influence of the increase rate of temperature surface of steel charge on the CO2 emission and the furnace productivity was conducted with regard to the increase in heating costs. The results of numerical modelling of the heating process in the pusher type steel reheating furnace were prese...

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

    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.

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

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

    2003-01-01

    resistance was evaluated in a commercial disinfectant and in 1 M NaCl. Electropolished and grit 4000 polished steel proved more corrosion resistant as opposed to grit 80 and 120 polished surfaces. In conclusion, the surface finish did not influence bacterial attachment, colonisation, or removal, but is an...... was not affected by surface roughness (Ra) ranging from grit 4000 polished stainless steel (Ra <0.01) to ground stainless steel (Ra 0.9). Neither adhesion of Ps. aeruginosa nor its removal by an alkaline commercial cleaner in a flow system was affected by surface roughness. Pitting corrosion...... important parameter for the corrosion resistance of the surface....

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

    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 ...

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

    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....

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

    A. Kurc-Lisiecka; M. Kciuk

    2013-01-01

    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 ...

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

    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 ...

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

    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...

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

    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...

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

    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...

  8. Influence of tempering on mechanical properties of ferritic martensitic steels

    In the mid-1980s research programs for development of low activation materials began. This is based on the US Nuclear Regulatory Commission Guidelines (10CFR part 61) that were developed to reduce long-lived radioactive isotopes, which allows nuclear reactor waste to be disposed of by shallow land burial when removed from service. Development of low activation materials is also key issue in nuclear fusion systems, as the structural components can became radioactive due to nuclear transmutation caused by exposure to high dose neutron irradiation. Reduced-activation ferritic martensitic (RAFM) steels have been developed in the leading countries in nuclear fusion technology, and are now being considered as primary candidate material for the test blanket module (TBM) in the international thermonuclear experiment reactor (ITER). RAFM steels developed so far (e.g., EUROFER 97 and F82H) meet the requirement for structural application in the ITER. However, if such alloys are used in the DEMO or commercial fusion reactor is still unclear, as the reactors are designed to operate under much severe conditions (i.e., higher outlet coolant temperature and neutron fluences). Such harsh operating conditions lead to development of RAFM steels with better creep and irradiation resistances. Mechanical properties of RAFM steels are strongly affected by microstructural features including the distribution, size and type of precipitates, dislocation density and grain size. For a given composition, such microstructural characteristics are determined mainly by thermo-mechanical process employed to fabricate the final product, and accordingly a final heat treatment, i.e., tempering is the key step to control the microstructure and mechanical properties. In the present work, we investigated mechanical properties of the RAFM steels with a particular attention being paid to effects of tempering on impact and creep properties

  9. FE-simulation of the viscoplastic behaviour of different RPV steels in the frame of in-vessel melt retentions scenarios

    Assuming the hypothetical scenario of a severe accident with subsequent core meltdown and formation of a melt pool in the reactor pressure vessel (RPV) lower plenum of a Light Water Reactor (LWR) leads to the question about the behavior of the RPV. One accident management strategy could be to stabilize the in-vessel debris configuration in the RPV as one major barrier against uncontrolled release of heat and radio nuclides. To get an improved understanding and knowledge of the melt pool convection and the vessel creep and possible failure processes and modes occurring during the late phase of a core melt down accident the FOREVER-experiments (Failure Of REactor VEssel Retention) have been performed at the Division of Nuclear Power Safety of the Royal Institute of Technology Stockholm. These experiments are simulating the behavior of the lower head of the RPV under the thermal loads of a convecting melt pool with decay heating, and under the pressure loads that the vessel experiences in a depressurization scenario. The geometrical scale of the experiments is 1:10 compared to a common LWR. This paper deals with the experimental, numerical, and metallographical results of the creep failure experiment EC-FOREVER-4, where the American pressure vessel steel SA533B was applied for the lower head. For comparison the results of the experiment EC-FOREVER-3B, build of the French 16MND5 steel, are discussed, too. Emphasis is put on the differences in the viscoplastic behaviour of different heats of the RPV steel. For this purpose, the creep tests in the frame of the LHF/OLHF experiments are reviewed, too. As a hypothesis it is stated that the sulphur content could be responsible for differences in the creep behaviour. (orig.)

  10. Influenced prior loading on the creep fatigue damage accumulation of heat resistant steels

    On two heat resistant power plant steels the influence of prior strain cycling on the creep rupture behaviour and the influence of prior creep loading on the strain cycling behaviour is investigated. These influences concern the number of cycles to failure and the rupture time being the reference values of the generalized damage accumulation rule and they are used for a creep fatigue analysis of the results of long term service-type strain cycling tests. (orig.)

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

    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...

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

    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.

  13. Hydrogen attack - Influence of hydrogen sulfide. [on carbon steel

    Eliezer, D.; Nelson, H. G.

    1978-01-01

    An experimental study is conducted on 12.5-mm-thick SAE 1020 steel (plain carbon steel) plate to assess hydrogen attack at room temperature after specimen exposure at 525 C to hydrogen and a blend of hydrogen sulfide and hydrogen at a pressure of 3.5 MN/sq m for exposure times up to 240 hr. The results are discussed in terms of tensile properties, fissure formation, and surface scales. It is shown that hydrogen attack from a high-purity hydrogen environment is severe, with the formation of numerous methane fissures and bubbles along with a significant reduction in the room-temperature tensile yield and ultimate strengths. However, no hydrogen attack is observed in the hydrogen/hydrogen sulfide blend environment, i.e. no fissure or bubble formation occurred and the room-temperature tensile properties remained unchanged. It is suggested that the observed porous discontinuous scale of FeS acts as a barrier to hydrogen entry, thus reducing its effective equilibrium solubility in the iron lattice. Therefore, hydrogen attack should not occur in pressure-vessel steels used in many coal gasification processes.

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

    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...

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

    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.

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

    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

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

    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

  18. Steel

    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

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

    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.

  20. Influence of additional elements on thermoelectric power of cast duplex stainless steel

    The mechanical properties of cast duplex stainless steel, which is used for main coolant pipes of pressurized water reactor type nuclear power plants, change due to thermal aging. Therefore it is advisable to evaluate these changes non-destructively for the maintenance of the plant components. In previous studies, it has been shown that thermoelectric power (TEP) measurement is an effective method for evaluating thermal aging of cast duplex stainless steel, and the change in TEP calculated from a model which simulates Cr concentration fluctuation was qualitatively corresponding to the change in measured TEP. But the TEP calculated from this model is different from the measured TEP. One of the reasons for this difference is considered to be the influence of other elements added in cast duplex stainless steel. In this study, the influence of C, Si, Mn, and Mo contained in stainless steel on TEP was investigated experimentally from the measurement results of Fe-Cr-Ni ternary alloys and Fe-Cr-Ni alloys containing one element of C, Si, Mn, and Mo. It was found that the addition of C, Si, and Mn changed TEP in a negative direction and addition of Mo changed TEP in a positive direction. In addition, calculated TEP of stainless steel from its chemical composition and the influence of C, Si, Mn and Mo based on the measurement results of model alloys became close to measured TEP. (author)

  1. INFLUENCE OF MICROSTRUCTURAL ANISOTROPY ON THE SPALLATION OF 1080 EUTECTOID STEEL

    While the influence of crystallographic texture on elastic and plastic constitutive response has seen extensive investigation in recent years, the influence of texture on the dynamic fracture of engineering materials remains less extensively explored. In particular, the influence of anisotropy, both textural and morphological, on the spallation behavior of materials remains poorly quantified. In this study, the spallation response of 1080-steel has been studied as a function of microstructural morphological anisotropy. In this study the influence of elongated MnS stringers, resident within a crystallographically isotropic eutectoid steel, on the spallation response of 1080 steel was investigated. That of a fully-pearlitic 1080 steel loaded to 5 GPa was found to be dominated by the heterogeneous nucleation of damage normal and orthogonal to the MnS stringers. Delamination between the matrix pearlitic microstructure and the MnS stringers was seen to correlate to a significantly lower pull-back signal during transverse loading than to that parallel to the stringer axis. The ''pull-back'' signals and post-spallation metallographic observations are discussed with reference to the influence of microstructural anisotropy on void nucleation and growth

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

    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.

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

    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

  4. Influence of the Zr and Ce on the structure of experimental hot-work tool steel

    L.A. Dobrzański

    2006-04-01

    Full Text Available Purpose: of this paper was to examine of the influence of the Zr i Ce on the structure of the newly developed complex hot-work tool steel 47CrMoWVTiCeZr16-26-8 in relation to standard hot-work tool steel X40CrMoV5-1.Design/methodology/approach: The investigations steels were made using the specimens made from the experimental steel, for which the working 47CrMoWVTiCeZr16-26-8 denotation was adopted, similar to the ones used in the ISO Standard on using the standard alloy hot-work tool steel X40CrMoV5-1. Both investigated steels were melted in a vacuum electric furnace. Specimens made from the investigated steels were heat treated with austenitizing in salt bath furnaces for 30 minutes in the temperature range of 970-1180°C with gradation of 30°C. Next, the specimens were tempered twice in the temperature range of 450-660°C for 2 hours.Findings: The 47CrMoWVTiCeZr16-26-8 steel quenched from the temperature of 1120°C has the martensitic structure with the small portion of the retained austenite and alloy carbides partially dissolved during austenitizing (about 3.5%, including the MC type carbides (based on ZrC, TiC, (Ti,VC and VC, with differing chemical compositions and crystallographic lattice parameter and of the M2C3 type (based on Ce2C3.Research limitations/implications: Basing on the investigations of the newly developed 47CrMoWVTiCeZr16-26-8 steel and the standard X40CrMoV5-1 steel, the most advantageous heat treatment conditions were determined to obtain thesis most advantageous structure and mechanical properties: for the 47CrMoWVTiCeZr16-26-8 steel quenching at the temperature of 1120°C and tempering at the temperature of 540°C, and for the X40CrMoV5-1 one quenching at the temperature of 1060°C and tempering at the temperature of 510°C.Originality/value: The newly developed hot-work tool steel include Zr and Ce characterizations good structure and can be used to hot work small-size tools which requires higher strength properties

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

    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)

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

    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.

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

    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 plas...

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

    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.)

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

    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.

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

    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.

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

    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)

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

    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...... demonstrate that a case of expanded austenite develops and that, in particular, strain-induced martensite has a large influence on the nitrided zone....

  13. Influence of Surface Finish on Fatigue Life of Steel Specimens Subjected to Pure Bending

    Roushdy, E. H.; Kandeil, A. Y.

    1990-01-01

    It has long been appreciated that surface conditions exert significant influence on fatigue behavior. The new capabilities of identifying and measuring surface parameters together with the significant development in data analysis by computers have facilitated the establishment of analytical models to quantify this influence. This paper displays the effect of surface Amplitude, Spacing and Hybrid parameters on the number of cycles to failure of standard steel specimens subjected to pure bendin...

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

    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...

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

    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

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

    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.

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

    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

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

    Solgaard, Anders Ole Stubbe; Michel, Alexander; Stang, Henrik; Geiker, Mette Rica; Küter, André; Edvardsen, Carola

    2009-01-01

    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...... resistivity of steel fibre reinforced concrete (SFRC). The parameters investigated in the following are the fibre geometry, the fibre volume and the transitional resistance. On basis of the experimental results, a model, taking the resistivity of the fibres and the concrete matrix into account is proposed....

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

    M. Opiela; W. Zalecki; A. Grajcar

    2012-01-01

    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...

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

    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.

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

    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...

  2. Influence of Silicon on Swelling and Microstructure in Russian Austenitic Stainless Steels Irradiated to High Neutron Doses

    Porollo, S.I.; Shulepin, S.V.; Konobeev, Y.V.; Garner, F. [Pacific Northwest National Laboratory, P.o. Box 999, Richland WA, AK 99352 (United States)

    2007-07-01

    Full text of publication follows: For some applications in fusion devices austenitic stainless steels are still considered to be candidates for use as structural components, but high neutron exposures must be endured by the steels. Operational experience of fast reactors in Western Europe, USA and Japan provides evidence of the possible use of austenitic steels up to {approx} 150 dpa. Studies aimed at improvement of existing Russian austenitic steels are being carried out in Russia. For improvement of irradiation resistance of Russian steels it is necessary to understand the basic mechanisms responsible for deterioration of steel properties. This understanding can be achieved by continuing detailed investigations of the microstructure of cladding steels after irradiation to high doses. By investigating the evolution of radiation-induced microstructure in neutron irradiated steels of different chemical composition one can study the effect of chemical variations on steel properties. Silicon is one of the most important chemical elements that strongly influence the behavior of austenitic steel properties under irradiation. In this paper results are presented of investigations of the effect of silicon additions on void swelling and microstructure of base austenitic stainless steel EI-847 (0.06C-16Cr-15Ni- 3Mo-Nb) irradiated as fuel pin cladding of both regular and experimental assemblies in the BOR-60, BN-350 and BN-600 fast reactors to neutron doses up to 49 dpa. The possible mechanisms of silicon's effect on void swelling in austenitic stainless steels are presented and analyzed. (authors)

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

    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.

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

    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).

  5. On factors influencing fatigue process in steel 316L used in hydrogen energy technologies

    Full text: Investigations of fatigue in steels exposed to hydrogen media is extremely important problem, hi this work, an austenitic stainless steel ASTM 316L resistant to hydrogen destructive influence is examined. The experiments presented have used hydrogen charged and uncharged specimens and were carried out under rotating bending and tension-compression fatigue in three different laboratories: at The University of Chemical Technology and Metallurgy, Sofia, Bulgaria; at Sandia National Laboratory, California and The University of Tufts, Medford, Massachusetts, USA; The Institute Hydrogenous at Kyushu University, Japan. The results are presented in Wohler curves complemented by 'Short fatigue crack length - Number of cycles' curves and 'Frequency - Lifetimes' plots, and compared respectively. key words: fatigue, hydrogen fatigue, stainless steel, Wohler curve, short fatigue crack

  6. Influence of selected rare earth metals on structural characteristics of 42CrMo4 steel

    J. Drápala

    2016-10-01

    Full Text Available The influence of rare earth metals (REM addition on solidification structure of the low-carbon 42CrMo4 steel was investigated. Alloys were prepared by means of a centrifugal casting. The addition of cerium, praseodymium or mischmetal in the steel produced greatly improved solidification structure with a suppressed columnar grain zone, finer grain size in the equiaxed grain zone. The additions occurred in the steel bath in the form of REM oxide and/or oxide-sulphide inclusions and as dissolved REM segregated along with other elements at prior grain boundaries and interdendritic spaces. Microstructure (light microscope, SEM/EDX chemical microanalysis, and TOF-SIMS analysis – mapping of elements in the structure of alloys were obtained.

  7. Researches concerning influence of magnesium, aluminum and titanium lime on steel desulfurization

    Putan, V.; Putan, A.; Josan, A.; Vilceanu, L.

    2016-02-01

    The paper presents the results of laboratory experiments on steel desulphurisation with slag from the system MgO-Al2O3-TiO2. To determine the influence, on the desulphurisation process, of the titanium oxide added in calcium aluminate slag, we experimented, in the laboratory phase, the steel treatment with a mechanical mixture consisting of lime, aluminous slag and slag obtained from the titanium making process through the aluminothermic technology. The steel melting was carried out in an induction furnace of 10 kg capacity, existent in the "Metallic Melts" laboratory of the Engineering Faculty of Hunedoara. During the research, we aimed to establish correlation equations between the sulphur distribution coefficient and the slag components (MgO, Al2O3, TiO2). The data obtained in the experiments were processed in MATLAB programs, resulting multiple correlation equations, which allowed the elucidation of some physical-chemical phenomena specific to the desulphurisation processes.

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

    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.

  9. Case histories of microbiologically influenced corrosion of austenitic stainless steel weldments

    Microbiologically influenced corrosion (MIC) is initiated or accelerated by microorganisms and is currently recognized as a serious problem affecting the construction and operation of many industrial facilities, including nuclear power plants. The purpose of this paper is to review how biofouling and MIC can occur and discuss current mechanistic theories. A case history of MIC attack in power plants is examined with emphasis on the role of welding and heat treatment variables using laboratory electrochemical analyses. Although MIC can occur on a variety of alloys, pitting corrosion failures of austenitic stainless steels are often associated with weldments. MIC occurs as the result of a consortium of microorganisms colonizing on the metal surface and their variety (fungi, bacteria, algae, mold, and slimes) enables them to form support systems for cross feeding to enhance survival. The metabolic processes influence corrosion behaviour of materials by destroying protective coatings, producing a localized acid environment, creating corrosive deposits, or altering anodic and cathodic reactions. On stainless steels, biofilms destroy the passive oxide film on the surface of the steels and subject them to localized forms of corrosion. Many of the MIC failures in industry result in pitting to austenitic stainless steel weldments. Pitting primarily occurs in the weld metal, heat affected zones, and adjacent to the weld in the base metal. Depending on the conditions of the concentration cell created by the biofilm, either phase of the two-phase duplex stainless steel, austenite or delta ferrite, may be selectively attacked. Theories have been proposed about the mechanism of MIC on austenitic stainless steel and and a general understanding is that some function associated with the biofilm formation directly affects the electrochemical process

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

    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...

  11. The Influence of Microstructure on Hydrogen Diffusion and Embrittlement of Multiphase Fine-Grained Steels with Increased Plasticity and Strength

    Begić Hadžipašić, A.; Malina, J.; Malina, M.

    2011-01-01

    The influence of microstructure on hydrogen diffusion and embrittlement of multiphase fine-grained structural steels with increased plasticity and strength was studied with electrochemical experiments which provide the hydrogenation of specimens in conditions simulating practice requirements. By means of all experimental data obtained from permeation experiments, mechanical investigations, SEM and EDS analyses, TRIP steel has shown greater resistance to hydrogen embrittlement than DP steel...

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

    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...

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

    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.

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

    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

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

    Jin, Hyun Ju; Kim, Ki Baik; Choi, Byoung Kwon; Kang, Suk Hoon; Noh, Sang Hoon; Kim, Ga Eon; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    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.

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

    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

  17. The influence of sigma phase on erosion and corrosion properties of duplex steel

    Z. Stradomski

    2010-07-01

    Full Text Available The paper presents the results of investigations concerning the influence of σ phase precipitating on the erosion and corrosion properties of ferritic-austenitic cast steel. The object of investigation have been two grades of corrosion-resistant cast steel: GX2CrNiMoCuN25-6-3-3 and GX2CrNiMoN25-6-3. The examinations have involved measurements for obtaining potentiodynamic curves, examination of erosion and corrosion resistance, and microstructural analysis. The supersaturated cast steel and the material after heat treatment have been examined. It has been found that the tribological properties of supersaturated cast steel are worse than those of the supersaturated and annealed cast steel. The highest erosion and corrosion resistance has been achieved as a result of ferrite decomposition δ → γ’+ σ. The examinations of corrosion resistance have revealed that the ageing process after supersaturation do not cause significant changes in the anti-corrosive properties.

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

    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 ...

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

    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

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

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

    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)

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

    Daniel Januário Cordeiro Gomes

    2015-04-01

    Full Text Available 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 influence of surface roughness of turned surfaces of AISI 4140 steel specimens on fatigue strength in the giga cycle or ultra-high-cycle fatigue range is evaluated. The fatigue experiments were carried out at room temperature, with zero mean stress, on a rotating-bending fatigue testing machine of the constant bending moment type. The fatigue strength of the specimens were determined using the staircase (or up-and-down method.

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

    Kateryna O. Kostyk

    2015-01-01

    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 ...

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

    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...

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

    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...

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

    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...

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

    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...

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

    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...

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

    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.

    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. The Influence of Gas Heating on Material Properties of P92 Steel During Boiler Tube Alignment

    Kladarić, Ivica; SAMARDŽIĆ, Ivan; Stoić, Antun

    2009-01-01

    The pipes and the pipe walls are of the utmost importance to all power plant facilities. Under exploitation, they are subjected to effects of aggressive media, high temperature corrosion and possible mechanical damage. Consequently, special attention is paid to the control of material properties during the power plant construction in order to minimize the risk of flaws or failures. In this paper, the influence of gas heating on the structure and properties of P 92 martensite steel is examined...

  12. Al and Si Influences on Hydrogen Embrittlement of Carbide-Free Bainitic Steel

    Yanguo Li; Cheng Chen; Fucheng Zhang

    2013-01-01

    A first-principle method based on the density functional theory was applied to investigate the Al and Si influences on the hydrogen embrittlement of carbide-free bainitic steel. The hydrogen preference site, binding energy, diffusion behaviour, and electronic structure were calculated. The results showed that hydrogen preferred to be at the tetrahedral site. The binding energy of the cell with Si was the highest and it was decreased to be the worst by adding hydrogen. The diffusion barrier of...

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

    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.

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

    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

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

    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

    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 carbon steel and its corrosion products on the leaching of elements from a simulated waste glass. Research document

    The influence of carbon steel and its corrosion products on leaching of elements from simulated high level radioactive waste glass (P0798) has been investigated in batch-type experiments of up to one year at 25±3degC under argon atmosphere (-1. For each series, a polished glass cube or glass particles were immersed in double distilled deoxidized water with powder of carbon steel or of magnetite, as an assumed carbon steel corrosion product, in the ratio of 10 gram carbon steel (or magnetite) to 1 litter of water. Normalized mass losses of Si, B, Na and Cs in the system of glass-carbon steel-water and of glass-magnetite-water apparently increased compared with those in the glass-water system. The glass dissolution could be accelerated by increasing hydroxyl ion resulting from hydrolysis of carbon steel or of magnetite. The pH values of leachate become eventually almost constant and it indicates that a steady state has been attained between these hydroxyl ion releases and its consumption, which is a disruption process of siloxane bond by hydroxyl ion in solution. The influence of carbon steel and its corrosion products on leaching of elements from the waste glass can be predominantly attributed to a pH effect in this experiment. The increase of glass corrosion rate, however, could be assessed within one order as an influence of the existence of carbon steel and/or its corrosion products. (author)

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

    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

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

    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.

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

    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.

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

    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

  2. Influence of the heat treatment on the mechanical properties and structure of TWIP steel in wires

    .W. Pilarczyk

    2007-06-01

    Full Text Available Purpose: The aim of this paper is to determine influence of the drawing process of TWIP steel wires on their mechanical properties and the structure changes.Design/methodology/approach: The heat treatment of steel containing 29.4 % manganese and little amount of carbon (0.0049%C allows to obtain TWIP effect, and the austenitic structure for this type of steel was realized. In order to investigate the structure changes, the optical microscopy was used. Mechanical properties were determined by the compression test and drawing process.Findings: The analyses of changes of mechanical properties and the structure after particular drawings stages was carried out. At the total draft of 93.4 % the value of drawing stress was 1060MPa, however further deformations of the wire brought relation Rm/R0.2 to be above 1.6.Research limitations/implications: Continuation of the investigations with the use of transmission electron microscopy makes it possible to identify all phases that appear in this steel.Practical implications: Drawn products characterized by high strength properties together with good plasticity might be used for production of connecting elements because they can absorb large quantity of energy.Originality/value: For the first time there were obtained so high hardening level as well as so high plasticity in the drawing process.

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

    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)

  4. Influence of the strain rate on the mechanical and technological properties of steel sheets

    M. Buršák

    2010-10-01

    Full Text Available The paper analyses the influence of strain rate on the behaviour of un-alloyed steels with Re (yield strength in the range of 210 … 550 MPa in the deformation process. It analyses the results of the influence of strain rate ranging from 10-3 to 2,5•102s-1 on the yield strength, the ultimate tensile strength (Rm, the elongation (A and the reduction of area (Z. Achieved results of strain rate in relationship on values of Erichsen number IE are also given. By increasing of strain rate ranging from 10-3 to 2,5•102s-1 the ratio Re/Rm is increased, whereas it was observed more intensively for steels with the lower value of Re. By increasing of strain rate up to 1 s-1 are IE values of tested steels increased, whereas the ratio Re/Rm was equal 0,82. After exceeding of this strain rate was the ratio Re/Rm increased and IE value is remarkable decreased.

  5. Microbiologically influenced corrosion of stainless steels - What is required for pitting?

    Hakkarainen, T.J. [VTT Industrial Systems, P.O. Box 1704, FIN-02044 VTT (Finland)

    2003-07-01

    Pitting of stainless steels in environments normally regarded as completely harmless is often attributed to microbial activity. In this paper, attention is drawn on one hand to the basic requirements for pitting of stainless steels to be possible, and on the other hand to various ways how microbial activity could contribute to a fulfilment of these requirements. For pit growth to be possible, three basic requirements must be fulfilled: (1) the environment must contain anions that can form an aggressive solution into the pit, (2) there must be a potential difference between the interior of the pit and the open surface outside the pit, (3) the temperature must exceed a critical value. The main factors that normally influence the possibility of pitting are the chloride content and the oxidising power of the environment, presence of anions other than chloride, temperature, possible presence of deposits on the steel surface, and the composition of the steel. Anions other than chloride in the bulk solution, including sulphate, usually have an inhibiting effect. Thiosulphate, however, is known to promote pitting under certain conditions. The possible ways of microbial activity to enhance pitting could include deposit formation leading to crevice type of attack, local modification of the composition of the environment to a more concentrated one, raising the electrode potential of the steel surface (''ennoblement''), or formation of reaction products that permit active dissolution inside a pit at lower potentials. Special attention is drawn to the possible action of thiosulphate by enhancing the anodic reaction at low potentials of the dissolving surface inside the pits. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  6. Influence of electro slag remelting (esr) slags on remelted tool steel

    CaF/sub 2/ base synthetic slag is used during the electroslag remelting technique. ESR slags are refining components of steel. They are usually ionic conductors and in the liquid state conduct electrical current due to mobility of the ions. Physical properties of the slag such as electrical conductivity, viscosity, melting point, density, surface tension and chemical stability at operating temperature influence the removal of inclusions from the metal and subsequent chemical composition of the alloy. Three different type of molten slags system were used in the ESR process to produce different grades of tool steel. It was concluded that the selected lumps of fluorspar (CaF/sub 2/=98%) can be prefused to decrease the level of impurities and can be used in combination with other three-component slag to achieve the similar properties of end product as in the case of imported CaF/sub 2/ base slag. (author)

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

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

    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.

  9. Carbon content influence on the peritectic reaction path in stainless steels

    J. Głownia

    2013-01-01

    Full Text Available An important role for the peritectic reaction path in castings of stainless steel play small changes in a carbon content (e.g. from 0,02 to 0,06 % C, at maintaining constant chromium and nickel values. An influence of the carbon content on the peritectic reaction stages constitutes the subject of studies. The calculations of the steel solidification pathways in the four-component system, of a constant chromium and nickel content of 18 % and 9 % – respectively and of various carbon content from 0,01 to 0,06 %, were performed. It was proved by means of the PANDAT program that the carbon concentration increases the Cr segregation and thereby changes the solidification path under actual conditions.

  10. Wide – Ranging Influence of Mischmetal on Properties of GP240GH Cast Steel

    J. Kasińska

    2012-12-01

    Full Text Available This paper presents influence of rare earth metals (REM on the properties of GP240GH cast carbon steel. The research has beenperformed on successive industrial melts. Each time ca 2000 kg of liquid metal was modified. The rare earth metals were put into the ladle during tapping of heat melt from the furnace. Because of this the amount of sulphur in the cast steel was decreased and the non-metallic inclusion morphology was significantly changed. It was found that non metallic inclusions the cracking mechanism of Charpy specimens and the impact strength were all changed. The following properties were tested: mechanical properties (y, UTS, plastic properties (necking, elongation and impact strength (SCI. In the three-point bend test the KJC stress intensity factor was evaluated.

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

    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)

  12. Influence of hydrogen-oxidizing bacteria on the corrosion of low carbon steel: Local electrochemical investigations.

    Moreira, Rebeca; Schütz, Marta K; Libert, Marie; Tribollet, Bernard; Vivier, Vincent

    2014-06-01

    Low carbon steel has been considered a suitable material for component of the multi-barrier system employed on the geological disposal of high-level radioactive waste (HLW). A non negligible amount of dihydrogen (H2) is expected to be produced over the years within the geological repository due to the anoxic corrosion of metallic materials and also to the water radiolysis. The influence of the activity of hydrogen-oxidizing bacteria (HOB) and iron-reducing bacteria (IRB) on carbon steel corrosion is considered in this study because of the high availability of energetic nutriments (H2, iron oxides and hydroxides) produced in anoxic disposal conditions. Local electrochemical techniques were used for investigating the activity of IRB as a promoter of local corrosion in the presence of H2 as electron donor. A local consumption of H2 by the bacteria has been evidenced and impedance measurements indicate the formation of a thick layer of corrosion products. PMID:24177135

  13. Influences of Spray Parameters on the Structure and Corrosion Resistance of Stainless Steel Layers Coated on Carbon Steel by Plasma Spray Treatment

    Stainless steel powders were sprayed on the grit-blasted SM45C carbon steel substrates using a plasma spray method. The influences of the spray parameters on the structure and corrosion resistance of the layers coated on the carbon steel were investigated. Corrosion behavior of the layers were analyzed by the anodic polarization tests in deaerated 0.1 M NaCl + 0.01 M NaOH solution at 80 .deg. C. The surface roughness and porosity were observed to decrease with decreasing the particle size. The surface hardness of the coating was always higher than that of the matrix, SM45C, implying that the higher resistance of the coating to erosion-corrosion than that of matrix, and increased as the spray power and the spray distance increase. Stainless steel coats showed more corrosion resistance than the carbon steel did, due to their passivity. The corrosion resistance of the coats, however, were inferior to that of the bulk stainless steels due to the inherent defects formed in the coats. The defects such as rough surface and pores provided the occluded sites favorable for the initiation of localized corrosion, resulting in the conclusion that finer the powder is, higher the corrosion resistance is. And the Cr oxides formation resulting in Cr depletion around the oxides reduced the corrosion resistance of the coats

  14. Influence of steel fibres on bond and development length of deformed bars in normal strength concrete

    Tenzey, Ugyen

    Transverse reinforcement (stirrups) plays an important role in improving bond and anchorage of deformed bars in reinforced concrete structures. Steel fibres or steel fibre reinforced concrete (SFRC) can be used in lieu of stirrups to provide a similar beneficial effect. The application of steel fibres in lieu of stirrups is not recognized in codes of practice for concrete structures because of limited research for this type of application. The results of this study are based on 18 large scale test beams (250 mm wide by 300 mm high and 3.4 m long). Control cylinders and flexure prisms are used to obtain the required concrete material properties together with tension tests of the steel rebar. The focus of this research is to investigate the influence of steel fibres to enhance bond and development of deformed reinforcing bars in normal strength reinforced concrete beams. An attempt is also made to develop an understanding and rationale of the effect SFRC has on improving bond. Longitudinal reinforcement in most of the beams is lap spliced with different types of confinement in the spliced region (plain concrete, plain concrete with stirrups, SFRC, and SFRC with stirrups), and evaluated under third point loading to ensure the spliced bars are subjected to a constant tensile force in the region of constant moment. All of the beams with spliced reinforcement failed in bond before yielding of the longitudinal reinforcement. The SFRC mix uses steel fibres at an 80 kg/m3 dosage (1% by volume). The plain concrete beams without any transverse reinforcement failed suddenly without any warning. The presence of steel fibres did not affect the flexural cracking load of the specimens, but did provide a consistent increase in the load capacity at bond failure and ensure a more controlled failure. The spliced beams with SFRC exhibited a 22.5% increase in the bond failure load capacity compared with the plain concrete beams. The combined effect of fibres and transverse reinforcement

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

    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)

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

    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.

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

    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 N2-fixation actually promoted the corrosion of 303 SS; however, the influence of the produced NH3 was negligible. It can be speculated that the electron transfer and/or the nitrogenase catalyzing the process may influence the corrosion.

  18. Influence of cooling rate on phase formation in spray-formed H13 tool steel

    McHugh, K.M. [Industrial Technology Department, Idaho National Laboratory, Idaho Falls, ID 83415-2050 (United States)], E-mail: kevin.mchugh@inl.gov; Lin, Y.; Zhou, Y.; Lavernia, E.J. [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States)

    2008-03-25

    Spray forming is an effective way to process many tool steels into near-net-shape molds, dies, and related tooling. The general approach involves depositing atomized droplets onto a refractory pattern in order to image the pattern's features. The pattern is removed and the die insert is mounted in a standard mold base or holding block. This approach results in significant cost and lead-time savings compared to conventional machining. Spray-formed dies perform well in many industrial forming operations, oftentimes exhibiting extended die life compared to conventional dies of the same material and design. Care must be exercised when spray forming tool steel dies to minimize porosity and control the nature and distribution of phases and residual stresses. Selection of post-deposition heat treatment is important to tailor the die's properties (hardness, strength, impact energy, etc.) for a particular application. This paper examines how the cooling rate during spray processing and heat treatment of H13 tool steel influences phase formation. Porosity and hardness were evaluated over a range of deposit cooling rates and residual stresses were evaluated for a die in the as-deposited condition. Finally, the performance of spray-formed dies during production runs in forging, extrusion, and die casting is described.

  19. Influence of Cooling Rate on Phase Formationin Spray-Formed H13 Tool Steel

    K. M. Mchugh; Y. Lin; Y. Zhou; E. J. Lavernia

    2006-04-01

    Spray forming is an effective way to process many tool steels into near-net-shape molds, dies and related tooling. The general approach involves depositing atomized droplets onto a refractory pattern in order to image the pattern’s features. The pattern is removed and the die is fitted into a standard holding fixture. This approach results in significant cost and lead-time savings compared to conventional machining, Spray-formed dies perform well in many industrial forming operations, oftentimes exhibiting extended die life over conventional dies. Care must be exercised when spray forming tool steel dies to minimize porosity and control the nature and distribution of phases and residual stresses. Selection of post-deposition heat treatment is important to tailor the die’s properties (hardness, strength, impact energy, etc.) for a particular application. This paper examines how the cooling rate and other processing parameters during spray processing and heat treatment of H13 tool steel influence phase formation. Results of case studies on spray-formed die performance in forging, extrusion and die casting, conducted by industry during production runs, will be described.

  20. Influence of cooling rate on phase formation in spray-formed H13 tool steel

    Spray forming is an effective way to process many tool steels into near-net-shape molds, dies, and related tooling. The general approach involves depositing atomized droplets onto a refractory pattern in order to image the pattern's features. The pattern is removed and the die insert is mounted in a standard mold base or holding block. This approach results in significant cost and lead-time savings compared to conventional machining. Spray-formed dies perform well in many industrial forming operations, oftentimes exhibiting extended die life compared to conventional dies of the same material and design. Care must be exercised when spray forming tool steel dies to minimize porosity and control the nature and distribution of phases and residual stresses. Selection of post-deposition heat treatment is important to tailor the die's properties (hardness, strength, impact energy, etc.) for a particular application. This paper examines how the cooling rate during spray processing and heat treatment of H13 tool steel influences phase formation. Porosity and hardness were evaluated over a range of deposit cooling rates and residual stresses were evaluated for a die in the as-deposited condition. Finally, the performance of spray-formed dies during production runs in forging, extrusion, and die casting is described

  1. Influence of Punch Velocity on Gas Hydrogen Embrittlement Behaviors in SA372 Steel

    When using hydrogen gas as an ecofriendly energy sources, it is necessary to conduct a safety assessment and ensure the reliability of the hydrogen pressure vessel against hydrogen embrittlement expected in the steel materials. In this study, by applying the in-situ SP test method, the gas hydrogen embrittlement behaviors in SA372 steel, which is commonly used as a pressurized hydrogen gas storage container, were evaluated. To investigate the hydrogen embrittlement behavior, SP tests at different punch velocities were conducted for specimens with differently fabricated surfaces at atmospheric pressure and under high-pressure hydrogen gas conditions. As a result, the SA372 steel showed significant hydrogen embrittlement under pressurized hydrogen gas conditions. The effect of punch velocity on the hydrogen embrittlement appeared clearly; the lower punch velocity case indicated significant hydrogen embrittlement resulting in lower SP energy. The fractographic morphologies observed after SP test also revealed the hydrogen embrittlement behavior corresponding to the punch velocity adopted. Under this pressurized gas hydrogen test condition, the influence of specimen surface condition on the extent of hydrogen embrittlement could not be determined clearly

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

    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.

  3. Experimental investigation of microbiologically influenced corrosion of selected steels in sugarcane juice environment.

    Wesley, Sunil Bala; Maurya, Devendra Prasad; Goyal, Hari Sharan; Negi, Sangeeta

    2013-12-01

    In the current study, ferritic stainless grades AISI 439 and AISI 444 were investigated as possible construction materials for machinery and equipment in the cane-sugar industry. Their performance in corrosive cane-sugar juice environment was compared with the presently used low carbon steel AISI 1010 and austenitic stainless steel AISI 304. The Tafel plot electrochemical technique was used to evaluate general corrosion performance. Microbiologically influenced corrosion (MIC) behaviour in sugarcane juice environment was studied. Four microbial colonies were isolated from the biofilms on the metal coupon surfaces on the basis of their different morphology. These were characterized as Brevibacillus parabrevis, Bacillus azotoformans, Paenibacillus lautus and Micrococcus sp. The results of SEM micrographs showed that AISI 439 and AISI 304 grades had suffered maximum localized corrosion. MIC investigations revealed that AISI 444 steel had the best corrosion resistance among the tested materials. However from the Tafel plots it was evident that AISI 1010 had the least corrosion resistance and AISI 439 the best corrosion resistance. PMID:23764955

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

    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.

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

    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

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

    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...

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

    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

  8. Operating conditions influence corrosion of carbon steel in a freshwater distribution system

    The influence of operating conditions (flow and no flow situations) on the corrosion of carbon steel (CS) were simulated and investigated. Conventional microbial culture methods and molecular tools were used to characterize the biofilm and corrosion causing bacteria. Denaturing gradient gel electrophoresis showed significant diversity and variation in the bacterial community. Raman spectroscopy was used to characterize the corrosion deposits, the following iron oxide phases were identified; lepidocrocite, goethite, hematite and magnetite. Transformation of two iron oxides hematite and magnetite vice versa was noticed in the experimental system. In conclusion a plausible CS corrosion control method was described. (author)

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

    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

  10. The influence of sulphate-reducing bacteria biofilm on the corrosion of stainless steel AISI 316

    This work investigates microbially-influenced corrosion (MIC) of stainless steel AISI 316 by two sulphate-reducing bacteria, Desulfovibrio desulfuricans and a local marine isolate. The biofilm and pit morphology that developed with time were analyzed using atomic force microscopy (AFM). Electrochemical impedance spectroscopy (EIS) results were interpreted with an equivalent circuit to model the physicoelectric characteristics of the electrode/biofilm/solution interface. D. desulfuricans formed one biofilm layer on the metal surface, while the marine isolate formed two layers: a biofilm layer and a ferrous sulfide deposit layer. AFM images corroborated results from the EIS modeling which showed biofilm attachment and subsequent detachment over time

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

    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.

  12. Evaluation of the Microbiologically Influenced Corrosion in a carbon steel making use of electrochemical techniques

    The Microbiologically Influenced Corrosion (MIC) has been identified as a problem of the nuclear plants systems in the last years. The electrochemical behavior of metal coupons of carbon steel submitted to the action of sulfate reducing bacteria (SRB) was evaluated, making use of the electrochemical techniques of direct current as well as electrochemical noise. The generated results show a little variation in the corrosion velocities which obtained by Tafel extrapolation and resistance to the linear polarization, whereas the electrochemical noise technique presented important differences as regards the registered behavior in environment with and without microorganisms. (Author)

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

    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.

  14. Al and Si Influences on Hydrogen Embrittlement of Carbide-Free Bainitic Steel

    Yanguo Li

    2013-01-01

    Full Text Available A first-principle method based on the density functional theory was applied to investigate the Al and Si influences on the hydrogen embrittlement of carbide-free bainitic steel. The hydrogen preference site, binding energy, diffusion behaviour, and electronic structure were calculated. The results showed that hydrogen preferred to be at the tetrahedral site. The binding energy of the cell with Si was the highest and it was decreased to be the worst by adding hydrogen. The diffusion barrier of hydrogen in the cell containing Al was the highest, so it was difficult for hydrogen to diffuse. Thus, hydrogen embrittlement can be reduced by Al rather than Si.

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

    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.)

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

    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.

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

    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 × 10−4 s−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

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

    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.

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

    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.

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

    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.

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

    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...

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

    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 ...

  3. Influence of non-metallic inclusions on fatigue strength of high manganese steel

    Six series of high manganese austenitic steel, which contain different inclusion quantity, were prepared. Fatigue experiments, tensile tests and Charpy tests were carried out. Influence of non-metallic inclusion and of temperature on the stress intensity threshold, fatigue crack propagation behavior, elastic-plastic fracture toughness and Charpy value were studied at room temperature and low temperature. In general, strength of this high manganese steel was reduced with increase of inclusion content. Influences of the direction of elongated inclusion with regard to the rolling direction on their strengths were also discussed based on SEM observation and numerical analysis for the stress concentration at a crack tip when an inclusion was near by the tip. According to these results, an inclusion acted as an obstacle to crack propagation for LT specimen. The roughness of fracture surface of ST specimen was larger than that of SL specimen, and the crack growth rate of the former was less than that of the latter. Fatigue life was increased with decrease of temperature, and mechanical parameters such as ΔKth and J1c were decreased with increase of temperature. The Charpy value decreased clearly with decrease of temperature

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

    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.

  5. Influence of crack depth on the fracture toughness of reactor pressure vessel steel

    The Heavy Section Steel Technology Program (HSST) at Oak Ridge National Laboratory (ORNL) is investigating the influence of flaw depth on the fracture toughness of reactor pressure vessel (RPV) steel. Recently, it has been shown that, in notched beam testing, shallow cracks tend to exhibit an elevated toughness as a result of a loss of constraint at the crack tip. The loss of constraint takes place when interaction occurs between the elastic-plastic crack-tip stress field and the specimen surface nearest the crack tip. An increased shallow-crack fracture toughness is of interest to the nuclear industry because probabilistic fracture-mechanics evaluations show that shallow flaws play a dominant role in the probability of vessel failure during postulated pressurized-thermal-shock (PTS) events. Tests have been performed on beam specimens loaded in 3-point bending using unirradiated reactor pressure vessel material (A533 B). Testing has been conducted using specimens with a constant beam depth (W = 94 mm) and within the lower transition region of the toughness curve for A533 B. Test results indicate a significantly higher fracture toughness associated with the shallow flaw specimens compared to the fracture toughness determined using deep-crack (a/W = 0.5) specimens. Test data also show little influence of thickness on the fracture toughness for the current test temperature (-60 degree C). 21 refs., 5 figs., 3 tabs

  6. INFLUENCE OF COLD WORK ON SIGMA PHASE FORMATION IN DUPLEX STAINLESS STEEL

    Rodrigo Magnabosco

    2012-09-01

    Full Text Available The formation of sigma phase in duplex stainless steels during isothermal aging is widely reported in the literature, but the influence of strain hardening prior to aging on the kinetics of formation of this phase was not a subject of systematic studies so far. The objective of this paper is to study the influence of cold work degree and aging time in aging at 650°C or 850°C of an UNS S31803 steel. Cold rolling was conducted, resulting in four sets of samples with 0%, 10%, 30% or 80% cross sectional area reduction. Those samples were submitted to isothermal aging between 10 minutes and 96 hours, followed by water quenching. Sigma phase quantification is possible after selective electrolytic etching with 10% KOH solution, and the volume fraction of ferrite is obtained with the aid of ferritscope. It is observed that increasing the strain hardening increases the possibility of heterogeneous nucleation of sigma phase within the ferrite grains, leading to increased rate of formation of sigma and consumption of ferrite with increasing aging time at both temperatures studied.

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

    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)

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

    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

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

    Liu, Xiangbing; Wang, Rongshan; Ren, Ai; Jiang, Jing; Xu, Chaoliang; Huang, Ping; Qian, Wangjie; Wu, Yichu; Zhang, Chonghong

    2014-01-01

    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.

  10. The influence of heat treatnemnt on the abrasive wear resistnace of a construction and a tool steel

    M. Orečný

    2015-01-01

    Full Text Available The paper deals about the influence of heat and chemical-heat treatment of construction steel 100Cr6 and alloy steel X210Cr12, which were treated according to their corresponding norms. The steel X210Cr12 was also treated in an unconventional way. The influence of the material structures and hardness on the abrasion wear resistance was studied. The influence of nitridation was considered in a way how to increase the abrasion wear resistance and how the heat treatment affects the hardness and the quality of the nitrided layer. The nitridation with diffusion annealing of the tested materials caused a decrease and also an increase of the materials wear resistances.

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

    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.

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

    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.

  13. Influence of proof stress, composition, and microstructure on acoustic emission during ductile fracture in medium- and high-strength steels

    Factors which influence high-amplitude acoustic emission during ductile crack extension in quenched and tempered low-alloy steel are discussed. A systematic approach was adopted to isolate the effects of compositional variables, microstructural variables, and strength level. Experimental steels were used to avoid the effects of uncontrolled changes in composition and manufacturing process which are inevitable when comparing steels which have been produced commercially. The effect on acoustic emission of the following variables was evaluated: 0.2% proof stress, carbon content, sulphur content, and sulphide morphology. It appears that proof stress is the most important factor governing the amount of high-amplitude acoustic emission generated as the result of ductile cracking in steels; a secondary influence is exerted by the sulphur content in steels which contain elongated manganese sulphide inclusions. The results indicated that very low levels of high-amplitude acoustic emission would be expected during the ductile cracking of steels with proof stress levels below about 1000 N mm-2. (author)

  14. INFLUENCE OF THERMAL DIFFUSION CARBONITRATION AND STRUCTURE OF DIFFUSION COATINGS ON MECHANICAL PROPERTIES OF P6M5 TOOL STEEL

    N. G. Kouhareva

    2014-12-01

    Full Text Available The paper investigates micro-structure, distribution of chemical elements in diffusion carbonitride coatings on P6M5 steel that have been obtained in powder cyanoless media at temperature 450–550 °C, distribution of micro-hardness and also results of the experiments on wear resistance executed at loads of 50 and 400 MPa.Influence of  machining temperature on  dimension and shape of  hardening phases is shown in the paper. The paper also considers influence of these characteristics on mechanical properties of carbonitrated P6M5 steel.

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

    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...

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

    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.

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

    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.

  18. Influence of annealing conditions on microstructure and phase occurrence in high-alloy CrMnN steels

    The influence of annealing at 750, 800, 850, 900 and 950 deg. C for 4 h on the microstructure and the phase occurrence in two high-alloy CrMnN austenitic stainless steels was investigated using light microscopy, transmission electron microscopy, and thermodynamic calculations. Austenite, σ, and Cr2N were identified in both steels experimentally. The experimental results were found to be in good agreement with the thermodynamic predictions. In one of the steels, M23C6 as a non-equilibrium probably residual phase was found. Cr2N appeared in the steels either in the form of discrete particles or as a part of cells consisting of alternate lamellae of Cr2N and austenite.

  19. Rupther: a simulation approach applied to a PWR vessel failure during a severe accident

    The Rupther program (Rupture Under Thermal Conditions) is a part of the international researches on severe accidents in the PWR type reactors. The aim of the program is the definition of failure simulation validated by experimental data on vessel steel 16MND5 mechanical properties. The paper presents the program and the first results. (A.L.B.)

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

    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...

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

    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)

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

    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.

  3. Influence of microstructure and load ratio on cyclic fatigue and final fracture behavior of two high strength steels

    Highlights: • The study was aimed at understanding effects of load ratios on fatigue properties. • The steels have better mechanical properties in comparison with rest in this category. • The steels were cyclically deformed at two different load ratios. • SEM was used to characterize the intrinsic features on the fracture surface. - Abstract: The results of a recent study aimed at understanding the conjoint influence of load ratio and microstructure on the high cycle fatigue properties and resultant fracture behavior of two high strength alloy steels is presented and discussed. Both the chosen alloy steels, i.e., AerMet® 100 and PremoMet™ 290 have much better strength and ductility properties to offer in comparison with the other competing high strength steels having near similar chemical composition. Test specimens were precision machined from the as-provided stock of each steel. The machined specimens were deformed in both uniaxial tension and cyclic fatigue under conditions of stress control. The test specimens of each alloy steel were cyclically deformed over a range of maximum stress at two different load ratios and the number of cycles to failure recorded. The specific influence of load ratio on cyclic fatigue life is presented and discussed keeping in mind the maximum stress used during cyclic deformation. The fatigue fracture surfaces were examined in a scanning electron microscope to establish the macroscopic mode and to concurrently characterize the intrinsic features on the fracture surface. The conjoint influence of nature of loading, maximum stress and microstructure on cyclic fatigue life is discussed

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

    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

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

    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.

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

    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)

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

    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

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

    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.

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

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

    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

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

    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.

  12. Influence of microstructure on the room temperature flow behaviour of Mod. 9Cr-1Mo steel

    The normalizing heat treatment conditions of T-91 grade steel were altered in order to get different austenite/martensite packet grain sizes. Tempering of the steel was carried out at (1) peak hardening temperature and (2) at temperature closer to commercial treatment. Tempering of these specimens, austenitized at a chosen temperature, at the two tempering temperatures resulted in the modification of the fine scale structure by the formation of different carbide types and their distribution. Tensile testing of these specimens (under all the three conditions) was conducted at ambient temperature in order to study the influence of the microstructures on the deformation behaviour. The flow stress, hardness and room temperature impact toughness showed an inverse relation with the martensite packet/austenite grain size. The deformation behavior of the specimens under the three heat treatment conditions was analyzed according to Ashby's model was made assuming. The slip length, λg, was estimated from the σ-ε1/2 plot and compared with the relevant microstructure parameters. The as-received material was seen to undergo aligatoring damage during cold rolling and a modification in their microstructure could render a defect free product. (author)

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

    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.

  14. Influence of Chemical Composition on Phase Transformation Temperature and Thermal Expansion Coefficient of Hot Work Die Steel

    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.

  15. Influence of surface mechanical activation of the X40Cr13 steel on roughness after ion and gas nitriding

    The article describes the problem of the thermal and mechanical activation of the surface of the X40Cr13 steel on the state of the ion and gas nitriding. in order to determine the nitriding influence and make the analysis of results, the steel was subjected to: soft annealing, hardening with subsequent tempering at T = 550 oC and also mechanical activation of the surface consisting in peripheral grinding with abrasive papers of the grain size 60, 360, 1000 and mechanical polishing. The main aim of this work was to establish the influence of different surface geometrical structure, depending on X40Cr13 steel structure, on the roughness profile after ion and gas nitriding. With regard to the above, the examinations of basic roughness parameters prior to and after thermochemical processes and the analysis of utilitarian usefulness of activations applied were carried out. (author)

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

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

    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.

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

    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)

  19. Influence of Cr content on the creep strength of modern 9 - 12%Cr steels

    Ferritic-martensitic 9-12% Cr steels have a key role in power plants as they permit thermally flexible operation. The goal is a delta ferrite free martensitic structure which ensures high strength. In long-term fatigue tests, the influence of the alloying elements Mo, W, Cu, Co, V, Nb, N, B were investigated while the Cr and C concentrations were varied at the same time. The investigations are accompanied by extensive microstructural investigations before and after application of the creep load. Computer-assisted programs like Thermocalc, DICTRA and MTDATA were applied at the same time for determining the equilibrium states of the structural phases and for simulating the kinetic structural changes under creep stress. (orig.)

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

    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.

  1. Influence of Laser Peening on Phase Transformation and Corrosion Resistance of AISI 321 steel

    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.

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

    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.

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

    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.

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

    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.)

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

    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

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

    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

  7. Influence of crystal orientation on hardness and nanoindentation deformation in ion-irradiated stainless steels

    Miura, Terumitsu; Fujii, Katsuhiko; Fukuya, Koji; Takashima, Keisuke

    2011-10-01

    The influence of crystal orientation on hardness and the range of plastic deformation caused by nanoindentation was investigated in a solution annealed type 316 stainless steel irradiated with Fe 2+ ions. The hardness was a function of grain orientation and was correlated with the Taylor factor averaged over three normal directions of the contact surface of the Berkovich indenter. The transmission electron microscope observations of the deformation microstructure under the indentations showed that the range of plastic deformation reached up to 10 times the indent depth for unirradiated material and depended on the orientation relation between the contact surface of the indenter and the slip directions. The range of plastic deformation decreased as the damage structure developed in ion irradiation.

  8. Influence of crystal orientation on hardness and nanoindentation deformation in ion-irradiated stainless steels

    Miura, Terumitsu, E-mail: miura@inss.co.jp [Institute of Nuclear Safety System, Incorporated, 64 Sata, Mihama-cho, Mikata-gun, Fukui 919-1205 (Japan); Fujii, Katsuhiko, E-mail: fujiik@inss.co.jp [Institute of Nuclear Safety System, Incorporated, 64 Sata, Mihama-cho, Mikata-gun, Fukui 919-1205 (Japan); Fukuya, Koji, E-mail: fukuya@inss.co.jp [Institute of Nuclear Safety System, Incorporated, 64 Sata, Mihama-cho, Mikata-gun, Fukui 919-1205 (Japan); Takashima, Keisuke, E-mail: maestro@mech.fukui-u.ac.jp [Graduate School of Nuclear Power and Energy Safety Engineering, University of Fukui, 910-8507, 3-9-1 Bunkyo, Fukui (Japan)

    2011-10-01

    The influence of crystal orientation on hardness and the range of plastic deformation caused by nanoindentation was investigated in a solution annealed type 316 stainless steel irradiated with Fe{sup 2+} ions. The hardness was a function of grain orientation and was correlated with the Taylor factor averaged over three normal directions of the contact surface of the Berkovich indenter. The transmission electron microscope observations of the deformation microstructure under the indentations showed that the range of plastic deformation reached up to 10 times the indent depth for unirradiated material and depended on the orientation relation between the contact surface of the indenter and the slip directions. The range of plastic deformation decreased as the damage structure developed in ion irradiation.

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

    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

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

    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.

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

    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.

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

    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 (Rct) obtained from EIS and the increase in corrosion current densities obtained from potentiodynamic polarization curves.

  13. The influence of the deposition parameters on the porosity of thin alumina films on steel

    DUSAN KICEVIC

    2004-03-01

    Full Text Available The influence of the deposition parameters on the porosity of thin alumina films electrophoretically deposited on steel from aqueous suspensions was investigated. The effects of the applied voltage, deposition time, suspension temperature and the solid content of the aqueous suspension on the porosity of the obtained alumina films have been determined using optical microscopy coupled with image analysis. It was shown that the lowest film porosity was obtained from a suspension containing 20 wt.% alumina powder at the lowest applied voltage (30 V, for a longer deposition time (10 min using a suspension temperature of 30 ºC. This behavior can be explained by the smaller amount of hydrogen evolved on the cathode during the electrophoretic deposition process.

  14. Influence of crystal orientation on hardness and nanoindentation deformation in ion-irradiated stainless steels

    The influence of crystal orientation on hardness and the range of plastic deformation caused by nanoindentation was investigated in a solution annealed type 316 stainless steel irradiated with Fe2+ ions. The hardness was a function of grain orientation and was correlated with the Taylor factor averaged over three normal directions of the contact surface of the Berkovich indenter. The transmission electron microscope observations of the deformation microstructure under the indentations showed that the range of plastic deformation reached up to 10 times the indent depth for unirradiated material and depended on the orientation relation between the contact surface of the indenter and the slip directions. The range of plastic deformation decreased as the damage structure developed in ion irradiation.

  15. Microbiologically influenced corrosion of stainless steel in a nuclear waste facility

    Corrosion in stainless steel cooling water piping in a nuclear waste processing facility occurred during an extended system lay-up. The failure characteristics indicated microbiologically influenced corrosion (MIC). The corrosion occurred at welds as pinhole penetrations in the surfaces, which opened into large subsurface void formations. Corrosive attack started in the heat-affected zones of the assembly welds, usually adjacent to fusion lines. Stepwise grinding, polishing, and etching in the affected areas revealed that voids generally grew in the wrought material as uniform, general corrosion. Tunneling (wormholing) erosion was also present. Selective attack occurred within the two-phase weld filler zone. The result was a void wall that was rough and porous-appearing, a consequence of preferential attack on the austenite. The three-dimensional spongy surface was studied optically and with the scanning electron microscope

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

    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.

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

    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.

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

    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)

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

    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.

  20. Influence of hard particle addition and chemical interdiffusion on the properties of hot extruded tool steel compounds

    Low alloyed steel bars were co-extruded with pre-sintered tool steel powders with the addition of tungsten carbides (W2C/WC) as hard particles. During the hot extrusion process of these massive and powdery materials, an extrudate is formed consisting of a completely densified wear resistant coating layer and a bulk steel bar as the tough substrate core. This work combines experimental measurements (EPMA) and diffusion calculations (DICTRATM) to investigate the effect of hard particle addition and its dissolution, as well as the formation of M6C carbides on the properties of two different PM tool steel coatings hot extruded with a 1.2714 steel bar. A carburization effect resulting from the W2C hard particles is responsible for an increase of the 1.2344 steel matrix hardness. The mechanical properties of the interface region between coating matrix and substrate are influenced by chemical interdiffusion of carbon and other alloying elements occurring during heat treatment.

  1. Influence of hard particle addition and chemical interdiffusion on the properties of hot extruded tool steel compounds

    Silva, P.A. [Max-Planck-Institut fuer Eisenforschung GmbH, MPIE, Max-Planck-Strasse 1, D-40237 Duesseldorf (Germany); Weber, S., E-mail: weber@wtech.rub.de [Institut fuer Werkstoffe, Ruhr-Universitaet Bochum, Universitaetsstrasse, D-44780 Bochum (Germany); Helmholtz-Zentrum Berlin, Glienicker Strasse 100, D-14109 Berlin (Germany); Inden, G. [Max-Planck-Institut fuer Eisenforschung GmbH, MPIE, Max-Planck-Strasse 1, D-40237 Duesseldorf (Germany); Pyzalla, A.R. [Helmholtz-Zentrum Berlin, Glienicker Strasse 100, D-14109 Berlin (Germany)

    2009-08-15

    Low alloyed steel bars were co-extruded with pre-sintered tool steel powders with the addition of tungsten carbides (W{sub 2}C/WC) as hard particles. During the hot extrusion process of these massive and powdery materials, an extrudate is formed consisting of a completely densified wear resistant coating layer and a bulk steel bar as the tough substrate core. This work combines experimental measurements (EPMA) and diffusion calculations (DICTRA{sup TM}) to investigate the effect of hard particle addition and its dissolution, as well as the formation of M{sub 6}C carbides on the properties of two different PM tool steel coatings hot extruded with a 1.2714 steel bar. A carburization effect resulting from the W{sub 2}C hard particles is responsible for an increase of the 1.2344 steel matrix hardness. The mechanical properties of the interface region between coating matrix and substrate are influenced by chemical interdiffusion of carbon and other alloying elements occurring during heat treatment.

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

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

    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 ...

  4. The influence of thermomechanical processing on the microstructure and mechanical properties of 13.5Cr ODS steels

    He, P., E-mail: pei.he@kit.edu [Institute for Applied Materials – Applied Materials Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); Lindau, R.; Moeslang, A. [Institute for Applied Materials – Applied Materials Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); Sandim, H.R.Z. [Departamento de Engenharia de Materiais, Escola de Engenharia de Lorena, University of Sao Paulo, Lorena, SP (Brazil)

    2013-10-15

    Highlights: • The influence of TMP on microstructure and mechanical properties has been studied. • The HIP + TMP ODS steel has a sharp rotated-cube {1 0 0} 〈1 1 0〉 texture component. • The microstructure of HIP + TMP ODS steel is partially recrystallized. • Total elongation is more orientation-dependent compared with the tensile strength. • USE is slightly increased from 1.5 to 2.1 J by TMP. -- Abstract: Reduced activation oxide dispersion strengthened (ODS) ferritic steels are the most promising structural materials for future fusion power plants and innovative fission nuclear reactors. The structure and mechanical properties of fine-grained 13.5% Cr ODS ferritic steels, processed by hot cross rolling to large strains of 70% and subsequent annealing have been investigated. The microstructure after hot cross rolling is partially recrystallized. The texture of the ODS ferritic steel after rolling and annealing has a sharp rotated cube ({1 0 0} 〈1 1 0〉) texture component. The γ-fiber component (〈1 1 1〉||normal direction) typical of recrystallized rolled ferritic steels is absent. Similar values of tensile strength are obtained for rolled samples regardless of the sample orientation in comparison with hot isostatically pressed samples whereas a substantial enhancement in total elongation (22%) is present at 500 °C. Cross-rolled ODS steels represent an increase in upper shelf energy to 2 J compared with hot isostatically pressed samples. The relatively poor toughness properties, compared to 9Cr ODS RAFM steel EUROFER ODS, can be attributed mainly to the absence of the γ-fiber texture component, bimodal grain size distribution and high amounts of interstitial impurities (O, N)

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

    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

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

    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

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

    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

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

    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 ...

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

    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)

  10. Influence of Low-Alloy Cast Steel Modification on Primary Structure Refinement, Type and Shape of Non-Metallic Inclusions

    Bartocha D.

    2015-04-01

    Full Text Available In the article there are presented methods and results of investigation which main aim were determination of influence of melting technology (gas extraction, vacuum refining, slag refining and extraction, deoxidation and degassing and type of used modifiers on the type and shape of non-metallic inclusions and the primary structure refining. Low alloy cast steel melted in laboratory conditions, in an inductive furnace was investigated. Additions of FeNb, FeV, FeTi and FeZr modifiers were applied. The contents of oxygen and nitrogen in obtained cast steel were determined.

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

    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...

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

    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)

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

    2014-01-01

    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 tem...

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

    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.

  15. Establishment of a cold cracking numerical criteria

    Low alloy steels present certain sensitivity to the so called cold cracking risk at welding. That risk takes place in the quenched martensitic zones, with the presence of hydrogen coming from the welding operation and appearance of the residual stresses at cooling. Facing that risk, welders have to take operating precautions to get safe welds. Besides the return of experience, the specification of the welding parameters often comes from standardized cracking tests, generally very conservative and empirical. Improvements of the numerical simulation offer new perspectives for a better mastering of the influential parameters involved in cold cracking. In the end it can also become of great help for the definition and justification for the use of specific welding precautions where the empirical tests may not fit the need due to excessive conservatism. The paper presents the work done within the framework of the development of a predictive numerical tool for the assessment of cold cracking risk during multipass welding of 16MND5 (SA 508 Gr3 Cl1) type steels. The first developments presented here are based on the mono-pass standardized 'implant test' on a 16MND5 steel with covered electrodes. The characterization of the heat affected zone obtained in that configuration is first set in terms of microstructure and microhardness, these data being essential regarding cold cracking risk. The influence of the presence of hydrogen on the martensite's mechanical characteristics is also discussed as the first inputs for setting a numerical cracking criterion. Some results of the numerical simulation using SYSWELD (thermo-metallurgical and mechanical tool with hydrogen diffusion) are compared with those from the experimentation. Thus are emphasized the metallurgical data needed for the development of such numerical simulation even if the tool used has already been proved to be reliable when used to predict strains and residual stresses after welding. (authors)

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

    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.

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

    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.)

  18. Influence of austenitic orientation on martensitic transformations in a compressed high manganese steel

    Highlights: → Parent orientation affects product kinetics, variant, size and orientation. → Martensite, like austenite twinning, forms fastest in compressed austenite. → The only one martensite variant formed in austenite leads to grain coarsening. → Both transformation and deformation contribute to final texture in martensite. - Abstract: High manganese TRIP/TWIP steels contain two types of martensite and the morphology, size, variant selection and texture of both types of martensite are influenced by the parent austenite grain orientation. In the present paper the TRIP effect was investigated in a compressed high manganese steel, focusing on the crystallographic behavior by means of X-ray diffraction and the electron back scatter diffraction (EBSD) technique. It is observed that γ austenite oriented with close to the compression axis (CA) transformed more easily into α'-martensite with only one variant, whereas the transformation in CA// and -oriented austenite was sluggish and often yielded several variants. This orientation dependency was ascribed to the ease of either deformation twinning or Shockley dislocation movement. Similarly, ε-M was also observed to transform smoothly into α'-M in nearly -oriented austenite and more sluggishly in other austenite grains of other orientations. However, the number of ε-M variants detected by EBSD was higher than direct observation. In contrast to thermally induced martensitic transformations, the TRIP effect during compression failed to cause grain refinement in the transformed α'-M. The rapid formation of α'-M in -oriented γ promoted the formation of a texture of the α'-M, whereas the texture developed in the austenite at high level of compression led to a restricted transformation into martensite. The reasons for the occurrence of a texture in the α'-M and for the behavior of the ε-M are discussed.

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

    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.

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

    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.

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

    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.

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

    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.

  3. Carbon steel protection in G.S. (Girlder sulfide) plants. Influence of the material surface state. Pt. 2

    The passivation on carbon steels, in particular ASTM A 516 Degree 60 and ASTM A 333 steels is made, submitting it to the action of H2S/H2O1,2 corrosive medium. The steel is rapidly corroded by H2S in aqueous solution, forming iron sulfides on the metallic surface in a crystalline layer of various μm of thickness. During this process, various types of iron sulfides at different phases, with different sulfur and iron contents are formed. The influence of temperature, the pH, the exposure time and the corrosive medium composition on formation and quality of the iron sulfides protective layer was also studied. (Author)

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

    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

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

    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.

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

    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

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

    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.

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

    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

  9. Mechanical behaviour of austenitic stainless steels in inert environment and in hot chloride environment: influence of molybdenum addition

    This research thesis reports the study of the influence of molybdenum addition. It is based on an experimental method which brings to the fore correlations between mechanical and electrochemical parameters of the phenomenon of stress corrosion cracking of austenitic stainless steels. After having recalled some characteristics of dry corrosion and electrochemical corrosion, presented austenitic stainless steels (mechanical properties such as elastic modulus, yield strength, tensile strength, ultimate elongation, creep behaviour, inter-crystalline and pitting corrosion, stress corrosion cracking behaviour), the author addresses the stress corrosion cracking behaviour of these steels in chloride environment (general characteristics, parameters, proposes theories to explain stress corrosion cracking), reports the study of the influence of molybdenum in these steels, notably on corrosion resistance and on stress corrosion cracking. Experimental method and results are described and discussed: tensile tests and creep tests in inert environment, stress corrosion cracking test in chloride environment with analysis based either on corrosion potential evolution or on sample elongation evolution. Results are notably discussed in terms of crack situation within metal lattice, crack growth rate, and scanning electronic microscopy observations

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

    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.

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

    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...

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

    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 ...

  13. Contribution on the influence of steel ladle processing (LF) upon the nitrogen removal rate

    Nitrogen, which is present in the composition of steel either dissolved or as a gas, represents an element, which is generally unwanted, except for the cases when the aim is to obtain nitrides or to increase the austenitic domain in stainless steels. The paper shows the results obtained in increasing the nitrogen removal rate during the secondary treatment of steel meant for oil industry pipes, into a Ladle Furnace-type installation. The processed data allowed the determination of variation domains, respectively graphical and analytical correlations between the nitrogen removal rate and the parameters of the secondary treatment process (bubbling duration, steel temperature and argon pressure)

  14. Influence of kinetics of supercooled austenite decomposition on structure formation in sparingly-alloyed tool steel

    Krylova, S. E.; Yakovleva, I. L.; Tereshchenko, N. A.; Priimak, E. Yu.; Kletsova, O. A.

    2013-10-01

    The decomposition of supercooled austenite in 70Kh3G2VTB steel under isothermal conditions and continuous cooling have been studied. The isothermal and continuous cooling tranformation curves of the decomposition of austenite in the experimental steel have been constructed. The effect of alloying elements on phase transformations in the steel under heating and cooling have been established. The features of the formation of a microstructure in the 70Kh3G2VTB steel after different regimes of heat treatment have been described. The optimal parameters of hardening heat treatment have been developed.

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

    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.

  16. A Study on the Influence of Steel, Slag or Gas on Refractory Reactions

    Jansson, Sune

    2008-01-01

    During the production of steel the oxide inclusion content partly depends on the reaction of the melt with the furnace lining, the ladle lining and the pouring system. The refractory material may be eroded by the molten steel and slag as well as corroded through chemical reactions with the slag and molten steel and the deoxidation products. In this report the effects of revolution speed, temperature and steel composition on the rate of dissolution of commercial MgO-C refractory samples into A...

  17. Assessment of molybdenum influence on long-term heat resistance of selected austenitic steel grades

    Analysis gave evidence that an increase in the long-term heat resistance by addition of approximately 2.5% molybdenum is, in the long run, more efficient in unstabilized austenitic CrNiMo(N) steels of the AISI 316 type than in stabilized X 6 CrNiMoTi 17 12 steel. The effect of molybdenum can be intensified or reduced by factors such as the stabilization ratio and grain size in stabilized CrNiMoTi steels, and the boron, nitrogen and carbon contents in unstabilized CrNiMo(N) steels. (Z.S.). 6 tabs., 6 figs., 62 refs

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

    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 ...

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

    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

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

    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.

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

    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.

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

    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

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

    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

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

    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.

  5. Influence of gaseous environments on rates of near-threshold fatigue crack propagation in nicrmov steel

    Liaw, Peter K.; Hudak, S. J.; Donald, J. Keith

    1982-09-01

    The influence of hydrogen environment (448 kPa) on near-threshold fatigue crack propagation rates was examined in a 779 MPa yield strength NiCrMoV steel at 93 °C. An automatically decreasing and increasing stress intensity technique was employed to generate crack growth rates at three load ratios (R = 0.1, 0.5, and 0.8). Results show that the crack propagation rates in hydrogen are slower than those in air for levels of stress intensity range, ΔK, below about 12 MPa√m. The crack closure concept does not explain the slower crack growth rates in hydrogen than in air. Near-threshold growth rates appear to be controlled by the levels of residual moisture in the environments. In argon and air, the fracture morphology is transgranular, while in H2 the amount of intergranularity varies with ΔK and achieves a maximum when the cyclic plastic zone is approximately equal to the prior austenite grain size.

  6. The Influence of Hydrogen on the Microstructure and Dynamic Strength of Lean Duplex Stainless Steel

    Silverstein, Ravit; Glam, Benny; Eliezer, Dan; Moreno, Daniel; Eliezer, Shalom

    2015-06-01

    In this research the dynamic strength of lean duplex stainless steel (LDS) with and without hydrogen was investigated. The LDS was chosen since it has a mixed structure of ferrite (BCC) and austenite (FCC) which allows an attractive combination of high strength and plasticity. Data collection was performed by VISAR and metallurgical analysis by post mortem observation. In addition, a thermal desorption process (TDS) was carried out in order to observe the influence of hydrogen charging on LDS crystal structure and to determine the hydrogen trapping mechanism before and after the plate impact experiments. Several assessments can be made based on the results of this study. TDS analysis revealed that even after hydrogen desorption, some hydrogen remained trapped in the austenitic phase causing a small lattice expansion. After impact, a brittle spall mechanism was seen, which occurred through crack progression along both phases grain boundaries. It was found that even small hydrogen content affects the dynamic strength of LDS. The relation between the microstructure and the dynamic strength of the LDS in the presence of hydrogen will be discussed. This work was supported by the Pazi foundation.

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

    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.

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

    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.

  9. Magnetic Barkhausen Noise and hysteresis loop in commercial carbon steel: influence of applied tensile stress and grain size

    The influence of applied tensile stress and grain size on Magnetic Barkhausen Noise and hysteresis loops in 1005 commercial steel is studied in this work. The peak amplitude of the Barkhausen voltage increases with the applied stress, reaching a maximum value and then beginning to decrease at higher tensile stress. This behavior is explained regarding the domain wall dynamics by the combined effect of the magnetic field and applied stress on the domain wall motion. The present study also reveals that the stress dependence on the MBN voltage and on the magnetic hysteresis loop is influenced by the grain size of the samples. The results show that MBN can be utilized to evaluate changes in the microstructural and mechanical properties of commercial carbon steels

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

    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...

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

    Lee, Sangwon; De Cooman, Bruno C.

    2016-04-01

    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.

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

    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.

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

    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...

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

    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...

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

    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...

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

    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.

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

    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

  18. Influence o the microstructure of duplex stainless steels on their failure characteristics during hot deformation

    Reis G.S.

    2000-01-01

    Full Text Available Two types of duplex stainless steels were deformed by torsion at a temperature range of 900 to 1200 °C and strain rate of 1.0 s-1 and their final microstructures were observed. The austenite volume fraction of steel A (26.5Cr - 4.9Ni - 1.6Mo is approximately 25% at room temperature, after conventional annealing, while that of steel B (24Cr - 7.5Ni - 2.3Mo is around 55%. Experimental data show that steel A is ductile at high temperatures and displays low ductility at low temperatures, while steel B has low ductility in the entire range of temperatures studied. At high temperatures, steel A is essentially ferritic and shows dynamic recrystallized grains after deformation. When steel A is strained at low temperatures and displays low austenite volume fraction, microstructural observations indicate that failure is triggered by grain boundary sliding due to the formation of an austenite net structure at the ferrite grain boundaries. At intermediate volume fraction, when austenite forms a dispersed second-phase in steels A and B, failure begins at the ferrite/ferrite boundaries since some of the new ferrite grains may become immobilized by the austenite particles. When steel B is strained at volume fraction of around 50% of austenite and both phases percolate the microstructure, failure occurs after low straining as a consequence of the different plastic behaviors of each of the phases. The failure characteristics of both steels are correlated not only with the volume fraction of austenite but also with its distribution within the ferrite matrix, which limits attainable strain without failure.

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

    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.

  20. The influence of elastic deformation on the properties of the magnetoacoustic emission (MAE) signal for GO electrical steel

    Magnetic properties of the grain oriented (GO) electrical steels are strongly affected by the stresses, both external and internal. The change is important even for the deformation resulting in stress level much lower than their yield limits. In this paper we present the results of investigation of the influence of compression and tension on the magnetoacoustic emission (MAE) signal properties. The experiment was performed with the help of bending machine in which the samples (0.3 mm thick, M140-30 S GO electrical steel) glued to the non-magnetic (austenitic steel) 8 mm thick bars were bent. The samples cut out in two directions (parallel and perpendicular to the rolling direction) were investigated. The elongation was measured directly with the help of tensometric bridge. Various parameters of the MAE signal, such as e.g. signal intensity and MAE peaks separation, have been examined. - Highlights: ► Magnetic properties of the GO electrical steels are strongly affected by stress. ► The non-destructive method of investigation of the ready-made components is needed. ► Magnetoacoustic emission is sensitive to stress-induced domain structure changes. ► Advanced signal analysis allows to determine the stress level in an unambiguous way.

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

    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.

  2. Influence of nitrogen on the structure and properties of chromium, chromium-molybdenum and chromium-manganese steels

    Phase transformations, precipitation processes and properties of the chromium, chromium-molybdenum and chromium-manganese steels with a high content of nitrogen as the dependence on thermal treatment were investigated. In case of Fe-0.08C-18Cr-18Mn-N and Fe-0.08C-18Cr-18Mn-2Mo-N steels the samples in the state after solution at temperature 1050oC and 1150oC and 1250oC and after subsequent annealing in 600oC and 800oC were investigated. heat treatment of the Fe-0.5C-10Cr-N and Fe-0.5C-10Cr-1Mo-N steels included austenitizment from 1000oC with air cooling and hardening from 1000oC with oil cooling and tempering in 650oC and 750oC in two hours with cooling in the air. These investigations show that the influence of nitrogen as an alloy element on the phase transformations, precipitation processes, mechanical and corrosion properties is connected with the presence of molybdenum and chromium in the steel. Nitrogen with these elements creates complex ions with the coordinate number 6. This statement is formed on the base of both calculations and investigation results. (author)

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

    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)

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

    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.

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

    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.

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

    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.

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

    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

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

    L.A. Dobrzański

    2009-08-01

    Full Text Available 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. Possible is also to examine the dependence among the selected steel property and chosen input parameters, which describes this property.Findings: There is no necessity of carrying out any additional material tests. The results correlations between calculated and measured values are very good and achieve even the level of 98%. Practical implications: Presented programme can be an effective replace of the real experimental methods of properties determination in laboratory examinations. It can be applied as the enlargement of experimental work. Possible is also the investigation of models coming from new steel species, that wasn’t produced yet.Originality/value: The ability of the mechanical properties estimation of the ready, or foreseen to the use, material is unusually valuable for manufacturers and constructors. This signifies the fulfilment of customer’s quality requirements as well as measurable financial advantages for material manufacturers.

  9. Influence of alloying elements on the corrosion properties of shape memory stainless steels

    Highlights: ► The corrosion properties of three Fe–Mn–Si–Cr–Ni–(Co) shape-memory stainless steels (SMSSs) were compared with those of a type 304 (SS 304) austenitic stainless steel. ► A considerably high Si content (about 40 at%) is present in the anodic passive films formed on SMSSs in 0.5 M H2SO4 solution. ► The high protectiveness of the anodic passive film formed on SMSSs in 0.5 M H2SO4 solution results from a protective film consisting of a (Fe, Cr)–mixed silicate. ► The SMSSs exhibited higher corrosion resistance than SS 304 in highly oxidizing environments. ► The SMSSs showed poor corrosion resistance in 3.5% NaCl solution compared to that of SS 304. - Abstract: The corrosion properties of three Fe–Mn–Si–Cr–Ni–(Co) shape memory stainless steels were studied based on X-ray photoelectron spectroscopy (XPS) analyses, immersion and polarization tests. The test results were compared with those of a type 304 austenitic stainless steel. The XPS analyses indicated substantial Si content in the anodic passive films formed on shape memory stainless steels in sulfuric acid solution and that the high protectiveness of these films results from a protective film consisting of a (iron, chromium)–mixed silicate. The corrosion rate of the shape memory stainless steels in boiling nitric acid solution was lower than that of austenitic stainless steel. The high silicon content was found to play an important role in the corrosion behavior of these shape memory alloys in highly oxidizing environments. Due to their high manganese content, the shape memory stainless steels showed poor corrosion behavior in 3.5% sodium chloride solution when compared with austenitic stainless steel.

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

    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...

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

    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)

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

    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.

  13. Influence of the counter-pressure casting on the macrostructure of high nitrogen steel industrial blocks

    The problem of high nitrogen steel (HNS) sheets production has not yet been solved. Sheets represent 90% of the world output of stainless and other steels, but there are no published data about HNS technologies and production of sheets on an industrial scale. The big steel bath (BSB) method and the counter-pressure casting (CPC) have proved the possibility of producing highly homogeneous ingots (1.3 and 10 tons) with all alloying elements, including nitrogen. In this way, the BSB and CPC methods have proved themselves to be universal ones for the production of shaped castings, HNS electrodes for remelting and sort, as well as, of sheets. (orig.)

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

    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.

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

    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)

  16. Evolution of mechanical properties of boron/manganese 22MnB5 steel under magnetic pulse influences

    Falaleev, A. P.; Meshkov, V. V.; Vetrogon, A. A.; Shymchenko, A. V.

    2016-02-01

    The boron/manganese 22MnB5 steel can be noted as the widely used material for creation of details, which must withstand high amount of load and impact influences. The complexity and high labor input of restoration of boron steel parts leads to growing interest in the new forming technologies such as magnetic pulse forming. There is the investigation of the evolution of mechanical properties of 22MnB5 steel during the restoration by means of magnetic pulse influence and induction heating. The heating of 22MnB5 blanks to the temperature above 9000C was examined. The forming processes at various temperatures (800, 900 and 9500C) were performed during the experiments. The test measurements allowed to obtain the relationships between the strain and the operation parameters such as induced current, pulse discharge time and the operation temperature. Based on these results the assumption about usage of these parameters for control of deformation process was made. Taking into account the load distribution and the plasticity evolution during the heating process, the computer simulation was performed in order to obtain more clear strain distribution through the processed area. The measurement of hardness and the comparison with the properties evolution during hot stamping processes confirmed the obtained results.

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

    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.

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

    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 of...... industrial tool used for high volume production of pump components, to compare forming of LDX 2101 and austenitic stainless steel with equal thickness. The forming forces, the geometry and the strains in the sheet material were compared for the same component. It was found that LDX steels can be formed to...... high strain levels in tools normally applied for forming of austenitic steels, but tool adaptations are needed to comply with the higher strength and springback of the material....

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

    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.

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

    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 Silica Fume on Corrosion Behaviour of Reinforced Steel in Different Media

    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.

  2. Influence on ultrasonic incident angle and defect detection sensitivity by cast stainless steel structure

    It is well known that ultrasonic waves are affected strongly by macro-structures in cast stainless steel, as in the primary pipe or other components in pressurized water reactors (PWRs). In this work, ultrasonic refractive angles and defect detection sensitivities are investigated at different incident angles to cast stainless steel. The aims of the investigation are to clarify the transmission of ultrasonic waves in cast stainless steel and to contribute to the transducer design. The results are that ultrasonic refractive angles in cast stainless steel shift towards the 45-degree direction with respect to the direction of dendritic structures by 11.8 degrees at the maximum and that the sensitivity of transducer for inner surface breaking cracks increases with decreasing incident angle. However, in an ultrasonic inspection of actual welds at smaller incident angles, a trade-off occurs between increased defect detection sensitivity and decreased defect discrimination capability due to intense false signals produced by non-defective features. (orig.)

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

    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.

  4. Study of reactions between nuclear fuel and cladding (316 stainless steel) in reactors. Influence of oxygen

    We have studied oxidation of 316 steel in close contact with oxides (Usub(0,74)Pusub(0,26)O2 or UO2), the stoichiometry of oxygen ranging from 2.00 to 2.5. Experiments are carried out either in a closed isothermal system or in an opened isothermal system with a fixed oxygen potential of uranium oxide. We have realized a potentiostatic device using a solid state electrotyte galvanic cell. In a closed system, the sensitized austenitic steel shows intergranular and volume oxidation probably enhanced by migration of steel components towards the fuel. Evidence of the usefulness of passivation have been obtained. We conclude that in a fast reactor sensitized cladding steel is oxydized by the constant potential of oxygen of UPuO2. Deposits observed in fuel can be explain by evaporation and cyclic transport phenomena that can be differents from VAN-ARKEL mechanism taking place through fission products

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

    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. RESEARCH OF INFLUENCE OF LIQUID ALUMINUM ON RESISTANCE OF THE STEEL AND CAST-IRON TOOL

    S. S. Zhizhchenko; I. A. Shpareva; M. A. Turchanin; P. G. Agraval

    2015-01-01

    The study of the interaction of steel and cast iron with aluminum was performed by immersion, and isothermal holding. By optical and electron microscopy, the microstructure of the reaction zone was investigated. The partial enthalpy of dissolution of iron, steel and cast iron in liquid aluminum has been investigated by high-temperature calorimetry at 1773 K. X-ray analysis and microhardness measurements was used to study the phase composition of the reaction zone. The thermodynamic descriptio...

  7. Influence of microstructure and environment on the fatigue behaviour of duplex stainless steels alloyed with nitrogen

    The favourable effect of nitrogen on the mechanical properties and the resistance to corrosion, now recognised for the austenitic stainless steels, aroused the interest for the development of dual - phase stainless steels constituted by austenite and ferrite (also labelled duplex steels) with high nitrogen content of which the interest lies in the lowest quantities of expensive alloying elements. The main purpose of this work is the study of the low cycle fatigue (LCF) behaviour of new grades of duplex steels and the determination of the microstructural scale conferring the best properties. LCF tests carried out in air on two duplex steels, with 0.24 wt% and 0.4 wt% of nitrogen and phase proportions of 50%α/50%γ and 30%α/70%γ respectively, led to the conclusion of a dependence of materials behaviour as a function of the strain level. The observations of samples by scanning electron microscopy showed that, for the lowest amplitudes, the plastic deformation is essentially accommodate by the austenite. Beyond a certain deformation, both phases alternatively accommodate this plastic deformation. In the presence of corrosive media, a general decrease of material fatigue lives has been noticed, except for the 0.4 wt% nitrogen containing steel which is less sensible. In the same way, an ageing treatment at 475 C for 200 hours lowers considerably the fatigue lives of the 0.24 wt% nitrogen steel while the resistance of the 0.4% nitrogen alloy is nearly unchanged. Whatever the conditions, the reductions of fatigue lives were systematically attributed to the ferritic phase behaviour. Then, elaborating these grades of duplex steels with 0.4 wt% of nitrogen favours a structure with 70% of austenite and leads to a very interesting fatigue behaviour. (O.M.)

  8. Influence of impact energy on work hardening ability of austenitic manganese steel and its mechanism

    Li Xiaoyun; Wu Wei; Zu Fangqiu

    2012-01-01

    To further understand the hardening mechanism of austenitic manganese steel under actual working conditions, the work hardening ability was studied and the microstructures of austenitic manganese steel were observed under different impact energies. The work hardening mechanism was also analyzed. The results show that the best strain hardening effect could be received only when the impact energy reaches or exceeds the critical impact energy. The microstructural observations reveal that disloca...

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

    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...

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

    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...

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

    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...

  12. Influence of the tritium in type 316L stainless steel on corrosion

    It is shown that the tritium in stainless steel induces stress corrosion by the effects of embrittlement due to both the tritium itself and the helium formed by its decay. These also cause local breakdown of the oxide layer, though this breakdown is also brought about by the β- ray energy, which can be estimated to be between 4 X 103 and 105 MeV/cm2 of the steel surface per second. 19 refs., 6 figs., 1 tab

  13. Influence of the pH and Temperature on Carbon Steel in the Secondary System of Nuclear Power Plants

    The broken pipes events occurred in the Surry unit 2 nuclear power plant in USA at 2004 and the Mihama unit 3 nuclear power plant in Japan at 1986 caused many casualties. It is mainly generated in the carbon steel pipe of the single-phase or two-phase. Also, most important influential factors of the FAC are known to be flow rate of the fluid, flow, pH, temperature, material contents and shape of the piping. The FAC is caused by the interaction of hydraulics factors and water chemistry factors. It can be mitigated effectually by the control of influential factors. In this study, the corrosion rate influenced by pH and temperature is evaluated in the single-phase by using the secondary system of power plant carbon steel. In this study, the pH and temperature effects on the carbon steel used in nuclear power plant secondary system were evaluated. Most effective factor on the corrosion rate is a solubility of magnetite and hematite produced by reaction between carbon steel and oxygen. The solubility of magnetite and hematite decreases for increasing pH, and it shows the highest value at 150 .deg. C temperature condition and decreases for higher temperature condition than 150 .deg. C. In this study, the experimental tests were performed for nuclear power plant operating condition of high temperature water chemistry environment using carbon steel specimen and static autoclave. The test results are showing consistent with the magnetite solubility trend. The static autoclave test is not able to consider the FAC phenomenon completely

  14. Parameters influencing the transgranular stress corrosion cracking behaviour of austenitic stainless steels in systems conveying reactor coolant

    During replacement of an auxiliary system in the German PWR KKS (NPP Stade) a damage was detected in a valve housing and in the connected piping both made from stabilised austenitic stainless steel. During operation stagnant conditions are present in this area. Based on the failure analysis chloride induced stress corrosion cracking (SCC) was found as the dominating root cause. In the open literature many cases of corrosion observed in the water/steam interface in valve components as well as in adjacent portions of auxiliary circuits made of un-stabilized stainless steels are mentioned. A common feature of the reported cases is that transgranular cracking was found. Extensive laboratory investigations revealed that non-stabilised austenitic stainless steels are also sensitive to transgranular cracking in boric acid solutions particularly in concentrated solutions. Often these solutions are contaminated with chlorides and/or oxygen is present. Taking into account the literature data the question could arise whether the above mentioned cracking may be also caused by boric acid attack. Thus, for stabilised stainless steels laboratory exposure tests at 80 C in saturated aerated boric acid solution and at 300 C in (at 100 C) saturated, oxygen free boric acid solution have been performed. Double-U-bend specimens and wedge loaded 1T-CT specimens made of Ti- and Nb-stabilised austenitic stainless steels were used. The results revealed no evidence of crack initiation and crack growth. Based on the laboratory results and the literature data an attempt is undertaken to separate parameters influencing chloride induced SCC from the effect of boric acid. (authors)

  15. Influence of sulfate-reducing bacteria on the corrosion of steel in seawater: laboratory and in situ study

    A fouling reactor was designed to study, the influence of a mixed bio-film on AISI 316 L stainless steel. The bio-film was formed on the steel surface by the fermentative bacterium Vibrio natriegens. The sulfate-reducing bacterium Desulfovibrio vulgaris was then introduced in the reactor and colonized the surface, constituting approximately 5 % of the total population. The settlement of an anaerobic bacterium in the bio-film shows in it the existence of anaerobic micro-niches. Stainless steel electrochemical behavior was analyzed using open circuit potential and potentiodynamic polarization curves. Growth of the bio-film does not induce corrosion, but seems to change the cathodic oxygen reduction kinetics, diminishing the corrosion hazard. This effect increases when D. vulgaris grows in the bio-film. An ennobling of the open circuit potential was observed, similar to field cases already described. A case of drilling corrosion of carbon steel in a harbour area showed the characteristics of anaerobic corrosion related to sulfate-reducing bacteria. The total cultivatable SRB population was quantified and metabolic types were enumerated using specific electron donors. A maximum cell density of 1,1 x 108 cells/ cm2 was estimated, revealing a very important growth of SRB on surfaces. Population structure was different in corroded and non-corroded areas. In corroded area, SRB utilizing benzoate and propionate were more abundant. A strain belonging to the sporulating genus Desulfotomaculum was isolated using these substrates, suggesting a partial aeration in the area of hole appearance. However, in vitro corrosion assays showed that the bacterial population sampled in this area induced a consequent weight loss of steel coupons, in the absence of oxygen. This was observed only with a diversified population, similar to that present in situ. It could not be reproduced with a mixed culture of two purified strains. (author)

  16. Influence of microelement addition on the pitting corrosion resistance of nitrogen-containing stainless steel

    To improve the performance of stainless steel, we subjected solid-state steel to a nitrogen absorption treatment. In the fabrication process, a commercially available high-chromium ferritic stainless steel (Fe-22Cr-1Mo) was heat-treated at 1423 K in a nitrogen atmosphere. The heat-treatment transformed the ferric phase into the austenite phase. This process loaded over 1 mass% of nitrogen into the steel material. Most of the added nitrogen formed a solid solution in the matrix, but a minor portion formed nitrides with the very small quantities of elements such as titanium and aluminum that pre-existed in the steel. The nitrogen-containing steels were then analyzed by pitting potential measurements and ferric chloride corrosion examination. The pitting corrosion resistance of Fe-22Cr-1Mo-1N exceeded that of conventional materials such as Fe-18Cr-12Ni and Fe-22Cr-1Mo. However in the ferric chloride corrosion tests, pits developed in Fe-22Cr-1Mo-1N at temperatures above 323 K. These pits were possibly initiated at the sites of minute nitride resulting from the nitrogen absorption process. (author)

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

    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)

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

    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.

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

    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.

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

    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.

  1. Microbiologically influenced corrosion evaluation on brass (UNS C68700, UNS C443) and AISI 316 stainless steel

    Microorganisms may play an important role in the corrosion process and generate conditions which affect the rate and/or the mechanism of deterioration. They become visible by the formation of bio films: clusters of microorganisms and extracellular polymers. These bio films affect not only the durability of the material, but also reduce the heat transfer. The present work studied the growth of aerobic and anaerobic heterotrophic microorganisms and sulfate reducing bacteria on aluminum brass (Uns C.a.), admiralty brass (Uns C.a.) and stainless steel Asi 316 in exposure experiments held in the Bay of Montevideo (Uruguay). The influence of the biofilm growth on the corrosion behavior was studied by electrochemical techniques: polarization curves and Electrochemical Impedance Spectroscopy (Ei). The selection of the most suitable material for the exposure conditions is discussed and hypotheses of the corrosion mechanism are presented. Although stainless steel Asi 316 presented the lowest corrosion rate it showed localized deterioration. (Author)

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

    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.

  3. Influence of external magnetic field on the etching of a steel ball in an aqueous solution of nitric acid

    The effect of change of shape of a steel ball was revealed as a result of its etching in an aqueous solution of nitric acid under influence of an external magnetic field. The elongation of a ferromagnetic ball was observed along the direction of an external magnetic field while etching took place uniformly in all the directions without magnetic field application. The steel ball etching in a magnetic field is characterized by formation of three cylindrically symmetric regions with different etching rates and surface structures, divided from each other by clear borders (namely, the pole, equator and transition regions are formed). The non-monotone dependences of etching rate, surface structure of a sample and sample shape after etching on an external magnetic field are observed.

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

    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.

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

    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

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

    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

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

    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

  8. Influence of Steel Fibers on the Structural Performance of a Prestressed Concrete Containment Building

    A large number of previous experimental investigations indicate that the use of steel fibers in conventional reinforced concrete (RC) can enhance the structural and functional performance of prestressed concrete containment buildings (PCCBs) in nuclear power plants. A prevention of through-wall cracks and an increase of the post-cracking ductility will improve the ultimate internal pressure capacity, and a high shear resistance under cyclic loadings will increase the seismic resisting capacity. In this study, the effects of steel fiber reinforced concrete (SFRC) on the ultimate pressure and seismic capacities of a PCCB are investigated. The effects of steel fibers on the ultimate pressure and shear resisting capacities of a PCCB are investigated. It is revealed that both of the ultimate pressure capacity and the shear resisting capacity of a PCCB can be greatly enhanced by introducing steel fibers in a conventional RC. Estimation results indicate that the ultimate pressure capacity and maximum lateral displacement of a PCCB can be improved by 16% and 64%, respectively, if a conventional RC contains hooked steel fibers in a volume fraction of 1.0%

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

    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.

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

    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.

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

    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

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

    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.

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

    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.

  14. Influence of microstructure of different stainless steels on their low cycle fatigue damage mechanisms

    The present study is focused on understanding low cycle fatigue damage mechanisms in three different kind of stainless steels. In all structures, crack propagation is conditioned by microstructural barriers. In single phase austenitic alloys, short cracks initiation and growth are crystallographic. Cracks are arrested by grain and twin boundaries both at surface and in the bulk. Grain size refinement improve the fatigue life at applied Δεp. The second barrier in the bulk is shown to be very efficient because of the important number of misoriented grains. In the metastable austenitic alloy, the martensitic transformation induced by cyclic straining leads to significant modifications of damage mechanisms. The fatigue behaviour has been investigated between -50 deg. C and 120 deg. C. The γ→α' transformation takes place at the surface, in the bulk (except at 120 deg. C) and locally at the crack tip. At all temperatures, the amount of martensite formed and the fatigue life increase as the grain size decreases, even if at the same Δεp, the maximal stresses are considerably higher than in a stable γ. Short cracks growth takes place in transformed regions, γ→α' transformation being assisted by strain concentrations at the crack tip. This mechanism consumes a part of plastic deformation, which would have been available for crack propagation. Such a dynamic barrier can decrease crack propagation rate. The austenite grain size is shown to have a decisive influence both on the amount of martensite formed and on the fatigue resistance through the effect of γ grain boundaries as indirect barriers to the crack propagation. The fatigue life of the 475 deg. C aged α/γ alloy decreases sharply at high applied Δεp compared to the solution annealed one. This behaviour is explained by the modification of short cracks nucleation sites. Indeed, cleavage occurs in the hard and brittle α phase, even if plastic deformation is concentrated in γ phase. Then, easy growth

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

    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.

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

    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)

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

    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.

  18. The influence of reinforcing steel bars on the apparent longitudinal ultrasonic pulse velocity in concrete: a simple mathematical model

    Low ultrasonic frequencies must be used in non-destructive testing of heterogeneous materials, such as plain and reinforced concrete,cast iron or timber.When frequencies are low enough,size and shape of tested bodies may influence the measured longitudinal pulse velocities.An approach which is named quasi fluid is applied to discuss the longitudinal pulse propagation in reinforcing steel bars embedded in concrete.Wave propagation is described by a spatially-averaged dilatation al field.An approximate formula is obtained which relates group velocity with and effective radius of the embedded bars with transducer frequency,and with the asymptotic P-wave velocity in steel and concrete,amongst other parameters.The evolution of a typical ultrasonic pulse is described using stationary-phase methods.Several known experimental facts are thus explained.finally,common use empirical correlation between the measured longitudinal pulse velocity and the diameter of embedded steel bars are discussed using the model developed in this paper

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

    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

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

    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.

  1. Enzymatic mechanism in low chloride media: influence of glucose oxidase on the electrochemical behaviour of AISI 316L stainless steel

    The open circuit potential (OCP) of stainless steels immersed in natural waters generally increases with time. This phenomenon is strongly linked to the formation of a bio-film on the surface. Several studies have proved that the bio-film modifies the reaction of reduction of dissolved oxygen and that it acts mainly on the cathodic processes. One of the hypotheses explaining the action of the bio-film involves certain bacteria which use dissolved oxygen and extracellular enzymes to produce reactive oxygen species. Among this kind of metabolites is hydrogen peroxide H2O2. This compound interacts with the passive layer of stainless steels and affects their electrochemical behaviour, even when the chloride concentration is low. The aim of this work is to study the influence of an enzymatic reaction (of the oxidoreductase type) on anodic and cathodic processes on AISI 316L stainless steel. Experiments are carried out in two artificial electrolytes simulating natural fresh waters, with two different chloride concentrations. The role of enzymatically-produced hydrogen peroxide is shown by OCP measurements and volt-amperometric methods. (authors)

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

    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.

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

    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.

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

    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...

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

    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

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

    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.

  7. Influence of Rare Earth Metals on Microstructure and Inclusions Morphology G17CrMo5-5 Cast Steel

    Kasińska J.

    2014-10-01

    Full Text Available This paper presents influence of rare earth metals (REM on the microstructure and morphology of non-metallic inclusions of G17CrMo5-5 cast carbon steel The research has been performed on successive industrial melts. Each time about 2000 kg of liquid metal was modified. The REM was in the form of mishmetal of the composition 49, 8% Ce, 21, 8% La, 17, 1% Nd, 5, 5% Pr and 5, 35% the rest of REM. Therareearth metals were put into the ladle during tapping of heat melt from the furnace.

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

    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)

  9. Influence of pre-deformation and oxidation in high temperature water on corrosion resistance of type 304 stainless steel

    Jinlong, Lv; Hongyun, Luo; Tongxiang, Liang

    2015-11-01

    The passivation properties of deformed 304 stainless steels after immersion in borate buffer solution containing 0.2821 mol/L Cl- at 288 °C were investigated. The spinel and magnetite oxides were formed on all the samples. However, the hematite oxides reduced significantly with the increasing of strain. The sample with maximum strain possessed the poorest corrosion resistance. The hematite oxide could offer high corrosion resistance, while magnetite evidently deteriorated corrosion resistance. Moreover, the influence of the donors in outer layer of oxide film on corrosion resistance was more important than that of the acceptors in inner layer.

  10. Laboratory investigation of microbiologically influenced corrosion of C1018 carbon steel by nitrate reducing bacterium Bacillus licheniformis

    Nitrate injection is used to suppress reservoir souring in oil and gas fields caused by Sulfate Reducing Bacteria (SRB) through promotion of nitrate respiration by Nitrate Reducing Bacteria (NRB). However, it is not well publicized that nitrate reduction by NRB can cause Microbiologically Influenced Corrosion (MIC) because nitrate reduction coupled with iron oxidation is thermodynamically favorable. NRB benefits bioenergetically from this redox reaction under biocatalysis. This work showed that the Bacillus licheniformis biofilm, when grown as an NRB biofilm, caused a 14.5 μm maximum pit depth and 0.89 mg/cm2 normalized weight loss against C1018 carbon steel in one-week lab tests

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

    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.

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

    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.

  13. The influence of rapid solidification on the microstructure of the 17Cr–9Ni–3Mo precipitation hardened steel

    Highlights: • Model of the microstructures formed at different cooling rates was proposed. • Effect of cooling rate on the massive formation of austenite was defined. • Influence of sub-zero treatment on the volume fraction of austenite was shown. - Abstract: The 17Cr–9Ni–3Mo precipitation hardened (PH) steel was processed after re-melting using different cooling rates including copper plate chilling and the melt-spinning. The effect of different cooling rates and the sub-zero treatment on the microstructure of the 17Cr–9Ni–3Mo steel was studied. The microstructure and the phase composition of the steel was investigated using light microscopy (LM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), the X-ray diffraction (XRD) and Mössbauer spectroscopy. The results show that the microstructure of 17Cr–9Ni–3Mo steel after rapid solidification consists of austenite and δ-ferrite. The quantity of austenite increases with the increase of cooling rate. Sub-zero treatment of the samples cooled at the rate of 4 × 104 K/s and 2 × 105 K/s reduces the quantity of austenite as a result of austenite → martensite transformation. For the samples cooled at the rate of 2 × 106 K/s the quantity of austenite in the microstructure does not change when compared to the state before and after sub-zero treatment. The model for the formation of microstructures during rapid cooling was proposed

  14. Influence of hot bending on microstructure changes of thick-walled P92 steel pipe

    Král, Petr; Sklenička, Václav; Kuchařová, Květa; Kvapilová, Marie; Svobodová, M.

    Toulouse : Institut Carnot CIRIMAT, 2015. s. 182-183. [CREEP 2015 - International Conference on Creep and Fracture of Engineering Materials and Structures /13./. 31.05.2015-04.06.2015, Toulouse] R&D Projects: GA TA ČR TA02010260 Institutional support: RVO:68081723 Keywords : hot bending * P92 steel pipe * creep behaviour * microstructure * EBSD Subject RIV: JG - Metallurgy

  15. Influence of the chemical composition on transformation behaviour of low carbon microalloyed steels

    In order to design thermomechanical schedules for processing low carbon microalloyed steels, the various critical transformation temperatures, i.e. the start and finish of the austenite transformation (Ar3, Ar1) and the non-recrystallization temperature (Tnr), must be determined. Continuous cooling torsion and compression testing are useful ways to measure these values. In this study six low carbon microalloyed steels with different additions (Nb, Cu, Si and Mo) were examined using these techniques. Moreover, the equilibrium phase diagrams for each alloy were calculated using FactSage. The comparison of the thermomechanical testing results with the thermodynamic calculations leads to a better understanding of the effect of the different elements on the transformation behaviour of pipeline steels. Regarding transformation temperatures, Cu in residual contents showed a strong effect on decreasing both Ar3 and Ar1, which indicates a hardenability effect of this element. On the other hand, increasing Nb contents increased Tnr by accelerating Nb(C,N) precipitation. However, when Si was added to a Nb-microalloyed steel, the Tnr decreased.

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

    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.

  17. The influence of heat treatment on microstructure and crack resistance of boron microalloyed steel plates

    M. Opiela

    2010-11-01

    Full Text Available crack resistance of C-Mn constructional steels with microaddition of boron assigned to be used in production of high strength steel plates.Design/methodology/approach: Metallographic observations, heat treatment, hardness measurements, impact strength examinations, fractographic analyses of fracture surfaces of test pieces have been performed.Findings: Dispersive particles of interstitial phases formed on dislocations during the plastic deformation, limiting grain growth of austenite, create the possibility to obtain metallurgical products with fine-grained microstructure giving them high strength and guaranteed crack resistance, also at low temperature.Research limitations/implications: Further research of microstructure in transmission electron microscope as well as complementary impact resistance tests at the temperature lower than -60°C are foreseen to be performed.Practical implications: Obtained results of examinations, especially detailed fractographic analysis of fracture surfaces of test pieces together with chemical composition analysis of revealed non-metallic inclusions and precipitations of secondary phases will make contribution to better understanding of cracking mechanisms in the group of high-strength steels.Originality/value: Performed research revealed that investigated steels present high crack resistance also at low temperature. It can be achieved through proper selection of chemical composition and adequate conditions of heat treatment and plastic working. The presence of microadditions of transition metals deriving from IVb and Vb group of periodic classification of the elements with high chemical affinity to nitrogen and carbon allows producing rolled products with high exploitation properties.

  18. Influence of plasma nitriding on the hardness of AISI 304 and low carbon steel

    Nitriding with plasma/ion nitriding technique for surface treatment of AISI 304 and low carbon steel as a machine component material has been done. Surface treatment is meant to improve the surface quality of metal especially its hardness. To reach the optimum condition it has been done a variation of nitriding pressure, while to analyse the result it has been done the hardness and microstructure test, and the nitrogen content. Result of the test indicates that: the optimum hardness obtained at 1.8 mbar of pressure that is 624.9 VHN or 2.98 times while the initial hardness is 210.3 VHN for AISI 304 and 581.6 VHN or 3.07 times compare with initial hardness 142.9 VHN for low carbon steel. The thickness of nitride layer for AISI 304 and low carbon steel is around 30 µm. Nitrogen contents after nitriding are 10.74% mass or 30.32% atom for AISI 304 and 6.81% mass or 21.76% atom for low carbon steel. (author)

  19. Influence of increasing notch radius on properties of nitrided hot work tool steels

    Rosso, M.; Scavino, G.; Ugues, D. [Politecnico di Torino - Dipt. di Scienza dei Materiali e Ingegeneria Chimica (Italy); Bennani, A. [COGNE Acciai Speciali - Aosta (Italy)

    2000-07-01

    Tool steels are a very large group of complex alloys which have evolved for many diverse hot and cold forming applications and they constitute a class of strategic materials. Hot work tool steels fall into groups which have either chromium, tungsten, or molibdenum as the major alloying element. The medium carbon and the relatively high alloy content make these steels air hardenable and resistant to impact and softening during repeated exposure to hot working operations. In this work the impact properties of Charpy U-notch samples with increasing notch radius are presented and discussed. The samples were manufactured with AISI H13 hot working tool steel and a modified composition, and were tested in the as quenched state and after nitriding. After the impact test, the microhardness properties were evaluated and correlated to the heat treatment. The notch radius strongly affect the impact resistance of the samples, namely at the lowest values. The microstructure details and the fracture morphology were observed by light microscopy and SEM. (orig.)

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

    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

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

    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.

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

    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.

  3. Influence of the surface finishing on electrochemical corrosion characteristics of AISI 316L stainless steel

    Dundeková, S.; Hadzima, B.; Fintová, Stanislava

    2015-01-01

    Roč. 22, č. 2 (2015), s. 77-84. ISSN 1335-0803 Institutional support: RVO:68081723 Keywords : AISI 316L stainless steel * EIS * Corrosion Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://ojs.mateng.sk/index.php/Mateng/article/view/167/278

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

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

    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.)

  6. Influence of non-metal inclusions on mechanical properties of Clam steel

    Full text of publication follows: With good irradiation swelling resistance, thermo-physical and thermo-mechanical properties, the RAFMs (Reduced Activation Ferritic / Martensitic steels) have been considered as the primary candidate structural materials for application in fusion systems in the near future. The China Low Activation Martensitic steel (CLAM) based on the nominal compositions of 9Cr1.5WVTa is being developed in Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) under wide collaboration with many other institutes and universities in domestic and overseas. The heat treatment of CLAM is quenching at 980 deg. C for 30 minutes and then cooled by air or water and tempering at 760 deg. C for 90 minutes and then cooled by air. Mechanical properties of CLAM were strongly affected by the size and distribution of non-metal inclusions as most steels, and its effects on mechanical properties of CLAM steel has been investigated. The evaluation of the non-metallic inclusions in CLAM has been done by optical microscopy observation, electron microscopy observation and Energy Dispersive X-ray Spectroscopy (EDS) analysis. The results showed that most of the non-metal inclusions in CLAM were brittle alumina phase with large size and non-uniform distribution and those were no good to the mechanical properties of CLAM. So electroslag remelting process was chosen to remelt the ingot which was smelted previously by vacuum induction furnace. Inclusion detection by optical microscopy showed that both of the dimensions and quantity of the inclusions decreased and their distributions became more uniform compared with the case before. And the tensile tests and Charpy V-notch impact tests indicated that electroslag remelting improved the tensile properties and impact toughness of CLAM steel. (authors)

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

    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)

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

    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.

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

    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.

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

    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.

  11. Influence of cold rolling on the corrosion resistance of austenitic steel

    A. Kurc

    2010-02-01

    Full Text Available Purpose: The paper analyzes the effects of plastic deformation in cold working process on the corrosion resistance, micro-hardness and mechanical properties of austenitic stainless steel X5CrNi18-10.Design/methodology/approach: Corrosion resistance of X5CrNi18-10 steel was examined using weight and potentiodynamic methods. In the weight method, the specimens were immersed in the prepared solution for 87 days. The evaluation of the corrosion behaviour of investigated steel in the potentiodynamic method was realized by registering of anodic polarization curves. The VoltaLab® PGP 201 system for electrochemical tests was applied. The tests were carried out at room temperature in electrolyte simulating artificial sea water (3.5% NaCl. Registering of anodic polarization curves was conducted at the potential rate equal to 1 mV/s. As the reference electrode the saturated calomel electrode (SCE was applied, the auxiliary electrode was platinum electrode. Mechanical properties were evaluated on the basis of the static tensile and Vickers micro-hardness test. The observations of the surface morphology after corrosive tests were carried out using Scanning Electron Microscope SUPRA™25.Findings: According to the results of potentiodynamic analyses it was found that plastic deformation in a cold working of austenitic steel grade X5CrNi18-10 affected to lower its corrosion resistance in 3.5% NaCl solution, what has an essential meaning in industrial applications of this group of materials.Research limitations/implications: The microscope observations of the surface samples subjected to corrosion resistance test in 3.5% NaCl solution permitted to evaluate types and the rate of corrosion damages.Practical implications: The obtained results can be used for searching the appropriate way of improving the corrosion resistance of a special group of steels.Originality/value: The corrosion behaviour in chloride solution of a Cr-Ni austenitic stainless steel was

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

    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

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

    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

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

    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

  15. Influence of impact energy on work hardening ability of austenitic manganese steel and its mechanism

    Li Xiaoyun

    2012-08-01

    Full Text Available To further understand the hardening mechanism of austenitic manganese steel under actual working conditions, the work hardening ability was studied and the microstructures of austenitic manganese steel were observed under different impact energies. The work hardening mechanism was also analyzed. The results show that the best strain hardening effect could be received only when the impact energy reaches or exceeds the critical impact energy. The microstructural observations reveal that dislocations, stacking faults and twins increase with raising impact energy of the tested specimens. The hardening mechanism changes at different hardening degrees. It is mainly dislocation and slip hardening below the critical impact energy, but it changes to the twinning hardening mechanism when the impact energy is above the critical impact energy.

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

    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.)

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

    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.

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

    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.

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

    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.

  20. Influence of the grain size on deleterious phase precipitation in superduplex stainless steel UNS S32750

    In the present work, the effect of grain size on deleterious phase precipitation in a superduplex stainless steel was investigated. The materials studied were heat treated isothermally at 800 deg. C, 850 deg. C and 900 deg. C for times up to 120 min. Hardness tests, light optical microscopy, scanning electron microscopy and X-ray diffraction were carried out to detect sigma and other harmful precipitate phases. The ferritic and austenitic grain sizes in the solution treated condition of the two steels analyzed were measured by electron backscattered diffraction (EBSD). Cyclic polarization corrosion tests were performed to evaluate the effect of grain size on the corrosion resistance. The results presented show that the precipitation of deleterious phases such as χ, σ and γ2, which can occur during welding and forming operations, is retarded by grain growth

  1. Influence of EPS isolated from thermophilic sulphate-reducing bacteria on carbon steel corrosion.

    Dong, Ze Hua; Liu, Tao; Liu, Hong Fang

    2011-05-01

    Extracellular polymeric substances (EPS) were isolated by centrifugation of thermophilic sulphate-reducing bacteria (SRB) grown in API-RP38 culture medium. The protein and polysaccharide fractions were quantified and the highest concentrations were extracted from a 14-day old culture. The effect of EPS on carbon steel corrosion was investigated by electrochemical techniques. At 30°C, a small amount of EPS in 3% NaCl solution inhibited corrosion, whilst excessive amounts of EPS facilitated corrosion. In addition, the inhibition efficiency of EPS decreased with temperature due to thermal desorption of the EPS. The results suggest that adsorbed EPS layers could be beneficial to anti-corrosion by hindering the reduction of oxygen. However, the accumulation of an EPS film could stimulate the anodic dissolution of the underlying steel by chelation of Fe2+ ions. PMID:21604218

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

    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.

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

    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...

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

    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...

  5. Influence of nitrogen on the corrosion fatigue behaviour of duplex stainless steels

    Combining a well adapted morphological texture to obtain a wavy crack propagation front with the effect of nitrogen which promotes slip reversibility in the austenitic phase, one can improve the corrosion fatigue resistance of duplex stainless steels in NaCl solutions. These structural factors allows to decrease the detrimental effect of hydrogen on the corrosion fatigue behaviour of the duplex alloys at imposed cathodic potentials. (authors). 3 figs

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

    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...

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

    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...

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

    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...

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

    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

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

    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...

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

    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 ...

  12. Influence of the surface finishing on the corrosion behaviour of AISI 316L stainless steel

    Dundeková, S.; Zatkalíková, V.; Fintová, Stanislava; Hadzima, B.; Škorík, Viktor

    2015-01-01

    Roč. 22, č. 1 (2015), s. 48-53. ISSN 1335-0803 R&D Projects: GA MŠk(CZ) EE2.3.30.0063 Institutional support: RVO:68081723 Keywords : AISI 316L stainless steel * Corrosion * Immersion test * Corrosion rate Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://ojs.mateng.sk/index.php/Mateng/article/view/166/251

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

    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 atmosphere on small punch testing of P91 steel

    Dymáček, Petr; Dobeš, Ferdinand

    Ostrava - Vítkovice : Ocelot, s.r.o, 2012 - (Matocha, K.; Hurst, R.; Sun, W.), s. 75-78 ISBN 978-80-260-0079-2. [Determination of Mechanical Properties of Materials by Small Punch and Other Miniature Techniques. Ostrava (CZ), 02.10.2012-04.10.2012] R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : small punch * steel P91 * creep Subject RIV: JG - Metallurgy

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

    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.

  16. Influence of non-metallic second phases on fatigue behaviour of high strength steel components

    To assess the real effect of the inclusion type on fatigue life of ultra clean high strength steels mechanical components made of 100Cr6 steel were fatigue tested and fracture surfaces analysed to determine the origin of fatigue cracks.Two heats proceedings from different steelmaking routes were taken for the tests. The material were forged into ring shape components which were fatigue tested under compression-compression loads. Failures were analysed by SFEM (Scanning field Emission Microscopy), proving that most of failures at high loads were originated by manganese sulphides of small size (10-70 micros), while less than 40% of all fatigue cracks due to inclusions were caused by titanium carbonitrides and hard oxides. It has been demonstrated that once number and size of hard inclusions have been reduced, the hazardous effect of oxides and carbonitrides on the fatigue life decreases also. However, softer inclusions as manganese sulphides, currently considered as less hazardous, play a more relevant role as direct cause of fatigue failure and they should be taken into account in a deeper way in order to balance both machinability and fatigue life requirements in high strength steel components. (Author) 11 refs

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

    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

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

    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.)

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

    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.

  1. Dislocation dynamics simulations of plasticity in Fe laths at low temperature

    Chaussidon, Julien [SIMaP-GPM2, Grenoble INP, CNRS/UJF, 101 rue de la Physique, BP46, 38402 Saint Martin d' Heres cedex (France); Robertson, Christian [Service de Recherches Metallurgiques Appliquees, CEA/Saclay, Building 455, 91191 Gif-sur-Yvette (France)], E-mail: christian.robertson@cea.fr; Rodney, David; Fivel, Marc [SIMaP-GPM2, Grenoble INP, CNRS/UJF, 101 rue de la Physique, BP46, 38402 Saint Martin d' Heres cedex (France)

    2008-11-15

    Plastic deformation in 16MND5 steel made of Fe laths is investigated using three-dimensional dislocation dynamics (DD) simulations, adapted to treat the body-centred cubic crystalline structure, strained in the ductile to brittle transition temperature range. In that regime, the edge segment velocity is proportional to the local effective resolved shear stress, whereas the screw segments follow a thermal activation scheme. The adopted cross-slip rules are derived from atomistic simulations, implemented in the DD code using a kinetic Monte Carlo algorithm. Specific loading and boundary conditions are worked out, with a view to accounting for the bainitic microstructure of the steel and its specific deformation mode. In these conditions, the implemented cross-slip behaviour is shown to play an essential role in the development of specific dislocation arrangements forming at different temperatures, also observed in 16MND5 steel. The presented results also provide insights on dislocation-based deformation mechanisms possibly involved in damage initiation.

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

    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

    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. Criterion of cleavage crack propagation and arrest in a nuclear PWR vessel steel

    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 molybdenum content on transformation behavior of high performance bridge steel during continuous cooling

    Highlights: ► The bainite transformation field was refined. ► The empirical equation to estimate the GFs was established. ► Transformation behavior was studied with serially increasing Mo addition. ► The molybdenum content can be lowered as the cooling rate is increased. ► GF transformation field is also shifted to right by increasing Mo content. - Abstract: The continuous-cooling-transformation (CCT) diagrams of high performance bridge steel with different molybdenum content were plotted by means of a combined method of dilatometry and metallography. The results show that the molybdenum addition of 0.17 wt% does not noticeably alter the transformation behavior, whereas 0.38 wt% significantly. In addition, the molybdenum addition of 0.38 wt% completely eliminates the formation of polygonal ferrite (PF) and significantly lower the granular ferrite (GF) transformation starting temperatures throughout the range of cooling rates studied. At lower cooling rates, with the increase of the molybdenum content, the martensite/austenite (M/A) constituents are noticeably refined, whereas the effects are not obvious at higher cooling rates. Moreover, the molybdenum addition of 0.38 wt% can significantly increase the Vickers hardness, but the Vickers hardness increments (by comparison of Mo-0.17wt% steel and Mo-0.38wt% steel) are sharply reduced at the cooling rate of 30 °C/s, indicating that at higher cooling rate, the molybdenum usage can be saved and the higher strengthen can be also gained. It could be found the GF transformation starting temperature is linear with the cooling rate. The empirical equation was established to calculate GF transformation starting temperatures, and the calculated values are in good agreement with measured ones

  6. Influence of strain rate and temperature on the mechanical behaviour of austenitic steel

    The mechanical behaviour of austenitic steel Z 6 NCTD 25-15 has been studied in regard to three parameters: strain-rate, temperature and precipitation state. After a structural study to determine the more convenient precipitation states, tensile and compressive tests have been performed between -1960C. and +8000C, in a strain-rate range laying between 10-5 s-1 and 103 s-1. Strain-rate temperature equivalence has been verified, but in some case, other phenomenons in deformation mechanism can occur, such twinning or Portevin Le Chatelier effect, wich make difficult this extrapolation

  7. Mechanical properties of austenitic stainless steel single crystals: Influence of nitrogen and hydrogen content

    Sucre, Y.R.; Iost, A.; Vogt, J.B.; Najjar, D.; Chumlyakov, Y.I.

    2000-01-01

    The effect of cathodically charged hydrogen in austenitic stainless steels with or without nitrogen addition was studied by microhardness experiments carried out on single crystals. With the authors experimental conditions, it can be demonstrated that hydrogen penetration depth is near 25 {micro}m and induced a higher apparent hardness. In fact, the hardness improvement is mainly a consequence of the residual stresses induced by hydrogen diffusion. By studying the variation of hardness with the reciprocal length of the indentation print obtained with load varying between 0.5 and 200 N, it was observed that the slope (VHN vs 1/d) only depends on the aging time.

  8. Influence of shadow effect on the strength of steel beams exposed to fire

    Virdi, Kuldeep; Wickström, Ulf

    2013-01-01

    -alone columns with I-cross section. In this paper, the temperature distributions in a steel beam with or without considering the shadow effect are calculated using the program TASEF. The resulting temperatures are then used to determine the fire duration under loading using a finite difference based computer...... in or in direct contact with concrete are not considered appropriately - only the reduction of the exposed area is taken into account. In addition, the shadow effect is rarely considered in structures with both concrete and asteel elements such as composite floors. It has been mainly used for stand...

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

    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...

  10. Influence of interstitial nitrogen on low cycle plastic fatigue behaviour of austenitic stainless steels

    Effect of interstitial nitrogen on austenitic steels tensile properties and low cycle fatigue is examined. Nitrogen content increases elasticity and strength by reducing ductility. Cyclic hardening shows a softening for low deformation and a hardening for high deformations. Stress evolution during cycling is discussed, especially in the accommodation phase. This phase comprises a initial hardening growing with nitrogen content up to 0.1% and a softening for higher contents. Life span in low cycle fatigue increases continuously with N content, for an imposed deformation over 1%. Analysis structure shows that nitrogen make dislocations flat, homogeneous and that arrangement in cells is delayed

  11. On the influence of cold rolling parameters for 14CrW-ODS ferritic steel claddings

    Oxide dispersion strengthened (ODS) steels, produced by powder metallurgy, are considered as promising material for high burn up cladding tubes for future Sodium Cooled Fast reactors. They present superior radiation resistance compared with austenitic steels and high creep strength due to reinforcement by the homogeneous dispersion of hard nano-sized particles. The aim of this study is to investigate several possible cold rolling routes for a Fe-14Cr-1W-0.3Ti-0.3Y2O3 ODS ferritic grade by comparing the effects of annealing temperature on cold-workability, microstructure evolution and mechanical properties. A three-roll type HPTR rolling mill is used to manufacture ODS steel claddings. Cold rolling passes and intermediate annealing are repeated until reaching the final geometry: 10.73 mm external diameter and 500 μm thick. Optical and TEM observations, hardness measurements and tensile tests are conducted to characterize three different cladding tubes. Microstructure of hot extruded mother tubes is highly anisotropic with equiaxed grains in the transverse direction but with significant elongation in the longitudinal direction. Despite the high temperature used for annealing during fabrication route, the elongated grain structure induced by the hot extrusion process is retained all along the cold manufacturing. Tensile tests are carried out on both longitudinal and circumferential directions by mean of respectively tile and ring tensile specimens for temperatures between 20 C and 700 C. The tensile properties obtained for the final tubes are dependent on the processing route, i.e. on the initial annealing temperature applied on the mother tube. For the lowest annealing temperature (1150 C), UTS values measured at room temperature are of about 1500 MPa in the longitudinal direction and of about 1300 MPa in the circumferential one. For higher annealing temperature (1250 C), UTS values are found around 1000 MPa in the both directions, showing a less pronounced

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

    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)

  13. Influence of long-term strain hold on creep-fatigue life of Mod.9Cr-1Mo steel

    Modified 9Cr-1Mo steel is the principal candidate material of a steam generator in a fast breeder reactor because of its superior high-temperature property. In this study, the influence of long-term strain hold on the failure life of Mod.9Cr-1Mo steel was investigated and the applicability of existing creep-fatigue life evaluation methods was discussed based on the experimental results. Creep-fatigue tests with hold time up to 10 hours per cycle at either tension or compression maximum strain were conducted under strain control of 0.5% and 1.0% at 550degC. Although failure life reduction occurred by introducing short hold period in the compression hold tests, the degree of reduction became smaller with increasing hold period. On the other hand, the failure life reduction became larger with increasing hold period in the tension hold tests. It was found that the failure life reduction in the compression hold tests was mainly due to the accumulation of tensile strain at the center of a specimen and that in the tension hold tests it was caused by intergranular damage in terms of creep cavity nucleation and growth from observation of the failure specimens. The time fraction rule adopted in a design code gave longer life compared to the experimental life, especially at low strain level. The failure life was well predicted by the ductility exhaustion method and the nonlinear damage accumulation model. (author)

  14. Influence of Surface Preparation on the Kinetics of Controlled Gas-Nitrided AISI H13 Steels Used in Extrusion Dies

    Akhtar, S. S.; Arif, A. F. M.; Yilbas, B. S.; Sheikh, A. K.

    2010-04-01

    In the aluminum extrusion practice, gas nitriding represents an important factor in enhancing the service life of AISI H13 steel dies. It is observed that if the die-bearing surface is not adequately prepared before nitriding, a nonuniform and shallow nitrided layer develops with reduced hardening effect. The focus of this paper is to investigate the influence of different surface conditions in terms of roughness on the kinetics of nitrided layer developed during gas-nitriding process under controlled nitriding potential. Four samples made of AISI H13 steel properly heat treated (quenched and tempered) were considered: without surface preparation, ground, polished, and lapped. All the samples were gas nitrided under the same conditions and examined after being nitrided. The nitrided layers were characterized using different techniques including optical microscopy, scanning electron microscopy, x-ray diffraction analysis, energy dispersive spectrometry mapping, and microhardness analysis. It was found that the surface preparation prior to nitriding significantly enhanced the nitriding kinetics, which in turn resulted in even and deep nitrided case depth. This provided high load-bearing capacity due to increased and deep hardening effect as compared to unprepared sample. A thinner and uniform compound layer with well-resolved phases was achieved in comparison with unprepared sample.

  15. The Influence of Temperature on the Frictional Behavior of Duplex-Coated Die Steel Rubbing Against Forging Brass

    Ebrahimzadeh, I.; Ashrafizadeh, F.

    2015-01-01

    Improvement of die life under hot forging of brass alloys is considered vital from both economical and technical points of view. One of the best methods for improving die life is duplex coatings. In this research, the influence of temperature on the tribological behavior of duplex-coated die steel rubbing against forging brass was investigated. The wear tests were performed on a pin-on-disk machine from room temperature to 700 °C; the pins were made in H13 hot work tool steel treated by plasma nitriding and by PVD coatings of TiN-TiAlN-CrAlN. The disks were machined from a two-phase brass alloy too. The results revealed that the friction coefficient of this tribosystem went through a maximum at 550 °C and decreased largely at 700 °C. Furthermore, the formation of Cr2O3 caused the reduction of friction coefficient at 700 °C. PVD coatings proved their wear resistance up to 550 °C, well above the working temperature of the brass forging dies.

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

    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

  17. Influence of C, N and Ti concentration on the intergranular corrosion resistance of AISI 316 Ti stainless steel

    The influence of Ti, C, and N concentration on the intergranular corrosion resistance of AISI 316 Ti stainless steel has been studied. A kinetic study of the corrosion process has been carried out using gravimetric tests according to ASTM A-262 practices B and C (Streicher and Huey, respectively). The TTS diagrams were drawn as a function of alloying elements concentration (C, N and Ti). Materials characterization under several test conditions was carried out using Scanning Electron Microscopy (SEM) analysing microstructural characteristics and the attack microstructure. The chemical resistance of these steels to intergranular test was function of N, C and Ti concentration. High Ti and N concentration favoured the precipitation of TiN during the material manufacture process. N forms TiN very stable, causing the removal of Ti from the matrix and, indirectly, favouring the Cr23C6 precipitation during the sensitization process and increasing the corrosion rate. In order to inhibit the intergranular corrosion in these materials the N and Ti concentrations must be optimised. (authors)

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

    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).

  19. Influence of original microstructure on the transformation behavior and mechanical properties of ultra-high-strength TRIP-aided steel

    Yin, Hong-xiang; Zhao, Ai-min; Zhao, Zheng-zhi; Li, Xiao; Li, Shuang-jiao; Hu, Han-jiang; Xia, Wei-guang

    2015-03-01

    The transformation behavior and tensile properties of an ultra-high-strength transformation-induced plasticity (TRIP) steel (0.2C-2.0Si-1.8Mn) were investigated by different heat treatments for automobile applications. The results show that F-TRIP steel, a traditional TRIP steel containing as-cold-rolled ferrite and pearlite as the original microstructure, consists of equiaxed grains of intercritical ferrite surrounded by discrete particles of M/RA and B. In contrast, M-TRIP steel, a modified TRIP-aided steel with martensite as the original microstructure, containing full martensite as the original microstructure is comprised of lath-shaped grains of ferrite separated by lath-shaped martensite/retained austenite and bainite. Most of the austenite in F-TRIP steel is granular, while the austenite in M-TRIP steel is lath-shaped. The volume fraction of the retained austenite as well as its carbon content is lower in F-TRIP steel than in M-TRIP steel, and austenite grains in M-TRIP steel are much finer than those in F-TRIP steel. Therefore, M-TRIP steel was concluded to have a higher austenite stability, resulting in a lower transformation rate and consequently contributing to a higher elongation compared to F-TRIP steel. Work hardening behavior is also discussed for both types of steel.

  20. Dynamic study of passive layers formed on stainless steels in chloride environment. Correlation with stress corrosion behaviour - influence of some alloying elements

    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

  1. Influence of metastable retained austenite on macro and micromechanical properties of steel processed by the Q and P process

    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

  2. Influence of PWHT on Toughness of High Chromium and Nickel Containing Martensitic Stainless Steel Weld Metals

    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.

  3. The influence of microstructural anisotropy on the delamination of duel phase steels

    Delamination is a well known phenomenon that occurs in dual-phase steels. This phenomenon is also evident in 3CR12, which has a dual-phase structure after hot rolling, and this often causes problems when thick plates are cut by shearing. Work on dual-phase and low alloy steels ascribed this delamination to the pancake shape of the grains, which is essentially an anisotropy in grain shape. In work on the delamination of 3CR12 it was shown that this grain shape anisotropy also contributes to the delamination. Crystallographic texture measurements on 3CR12 show that the material has a strong, preferred-orientation in the hot-rolled condition. Texture measurements were carried out with an x-ray diffractometer using Mo radiation. It was found that 3CR12 delaminates as a result of anisotropy in grain shape and the presence of bands of orientations of {100}(uvw) and {111}(uvw) type textures. However, brittle cleavage was found at an angle of 45 degrees to the rolling direction, which indicates an effect from the crystallographic preferred-orientation. At lower temperatures this effect is enhanced by the formation of large brittle areas at angles of 45 degrees to the rolling plane, a result that can only be explained in terms of crystallographic texture. 12 refs., 14 figs., 1 tab

  4. Influence of technetium on the microstructure of a stainless steel-zirconium alloy

    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

  5. Influence of fluence rate on radiation-induced mechanical property changes in reactor pressure vessel steels

    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.

  6. Influence of Thermal Aging on Primary Water Stress Corrosion Cracking of Cast Duplex Stainless Steels

    In order to evaluate the SCC (stress corrosion cracking) susceptibility of cast duplex stainless steels which are used for the main coolant piping material of pressurized water reactors (PWRs), the slow strain rate test (SSRT) and the constant load test (CLT) were performed in simulated PWR primary water at 360 C. The main coolant piping materials contain ferrite phase with ranging from 8 to 23 % and its mechanical properties are affected by long time thermal aging. The 23% ferrite material was prepared for test as the maximum ferrite content of main coolant pipes in Japanese PWRs. The brittle fracture in the non-aged materials after SSRT is mainly caused by quasi-cleavage fracture in austenitic phase. On the other hand, a mixture of quasi-cleavage fracture in austenite and ferrite phases was observed on long time aged material. Also on CLT, (2 times σy), after 3,000 hours exposure, microcracks were observed on the surface of non-aged and aged for 10,000 hours at 400 C materials. The crack initiation site of CLT is similar to that of SSRT. The SCC susceptibility of the materials increases with aging time. It is suggested that the ferrite hardening with aging affect SCC susceptibility of cast duplex stainless steels. (authors)

  7. The influence of low oxygen and contaminated sodium environments on the fatigue behavior of solution treated AISI 316 stainless steel

    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 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)

  8. Mechanosynthesis of zinc ferrite in hardened steel vials: Influence of ZnO on the appearance of Fe(II)

    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

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

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

  10. Influence of some additives to the kinetics of Zn-crystal growth onto continuous hot dip galvanized steel

    In this work we made attempt on determination of the gefree, of influence, of the different types of additives on zinc spangle growth during forming of zinc coating, at the process of continues hot deep galvanizing of steel strip. All investigations were made at cold rolling mill plant 'Ladna Valavnica'-Skopje - HDG line, Additives were implied manually using hand pump directly on full hard strip, just before annealing furnace. Three types of additives were used in unchanged state as well as their mixtures. Analysis of the results included macro photograph of the surface, microphotograph of the zinc coating as well as different attempts of mathematical models. During investigation all technological parameters (cleanness of the strip from the emulsion marks, temperatures of the different zones of the furnace, temperature of the molten zinc and chemical composition of the zinc pot) remained at their constant values. (Original)

  11. Factors influencing the growth of cracks from defects in CDFR specification 316 stainless steel thermal shock specimens

    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)

  12. Influence of additives on electrodeposition of bright Zn–Ni alloy on mild steel from acid sulphate bath

    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.

  13. The influence of low oxygen and contaminated sodium environments on the fatigue behaviour of solution treated AISI 316 stainless steel

    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)

  14. Influence of defect states on band gaps in the two-dimensional phononic crystal of 4340 steel in an epoxy

    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.

  15. The influence of titanium interlayers on the adhesion of PVD TiN coatings on oxidized stainless steel substrates

    It has been shown that the use of thin titanium interlayers improves the coating-substrate adhesion of physical vapour deposition (PVD) titanium nitride thin films on a stainless steel substrate. This improvement arises from a combination of chemical gettering and mechanical compliance effects. The improved adhesion of plasma-assisted chemical vapour deposition TiN coatings with increasing interlayer thickness has been shown to be largely attributable to the compliance effect. The development of practical methods to improve adhesion is hampered by the difficulties involved in quantitative measurements of the effect. To avoid the influence of the intrinsic and extrinsic parameters involved in scratch test and microhardness measurements, efforts have been made to apply fracture mechanical testing methods to the determination of the adhesion strength of the film on the substrate (S. Berg, S. W. Kim, V. Grajewski and E. Fromm, Mater. Sci. Eng. A, 139 (1991) 345). In our study the influence of Ti interlayers on the adhesion of PVD TiN coatings on oxidized stainless steel substrates was investigated using a pull-off test for adhesion measurements and scanning tunnelling microscopy and secondary ion mass spectrometry for analysis of the fractured surfaces. It was shown that the thickness of the Ti layer must be chosen according to the thickness of the oxide layer. An excess of Ti leads to lower adhesion values due to failure in the Ti layer, while a shortage of Ti leads to unreacted oxide and minimum adhesion due to brittle fracture in the oxide layer, which was shown to be amorphous. (orig.)

  16. The quenching influence on defect structure and far acting stress fields of the 30CrNi3MoVA steel

    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.

  17. The quenching influence on defect structure and far acting stress fields of the 30CrNi3MoVA steel

    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.……

  18. The influence of pluronic P123 micelles on corrosion behaviour of steel in cement extract and bulk matrix properties of cement paste

    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)

  19. Influence of heat treatment on microstructure and properties of GX12CrMoVNbN9-1 cast steel

    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.

  20. Study by factorial analysis of the influence of chemical composition on the stress corrosion cracking of austenitic stainless steels

    The stress corrosion cracking of austenitic stainless steels has been treated by factorial correspondence analysis. This statistical method gives a relationship between chemical characteristics and the susceptibility of the steels to the phenomenon

  1. Influence of alumina and titanium dioxide coatings on abrasive wear resistance of AISI 1045 steel

    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.

  2. Influence of cryogenic treatment on the wear characteristics of 100Cr6 bearing steel

    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%.

  3. Factors influencing the Zn and Mn extraction from pyrometallurgical sludge in the steel manufacturing industry.

    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

  4. Influence of annealing on grain boundary segregation of neutron irradiated type 316L stainless steel

    Type 316L stainless steel was neutron irradiated (8x1025 n/m2, E>1MeV) and annealed at 673 K - 973 K for 1 hour. After the annealing, intergranular fracture ratio measurement by SSRT, grain boundary analysis by FE-TEM with EDS and simulation of grain boundary Cr depletion healing were performed in order to consider an effect of segregation healing on IASCC. The intergranular fracture ratio was healed to 0% by annealing above 723 K, but the healing of grain boundary Cr depletion of 723 K annealed specimen was not recognized by EDS analysis. Considering about the EDS analysis result and analysis probe diameter, concentration profiles were calculated. As a result, it was considered that grain boundary segregation which depleted to about 8 mass% by neutron irradiation, healed to about 12 mass% by annealing at 723 K, so that IASCC susceptibility was decreased. (author)

  5. Influence of localized plasticity on oxidation behaviour of austenitic stainless steels under primary water reactor

    Cissé, Sarata [CEA Saclay, DEN/DANS/DMN/SEMI, 91191 Gif-sur-Yvette Cedex (France); Laffont, Lydia, E-mail: lydia.laffont@ensiacet.fr [Institut CARNOT, CIRIMAT-ENSIACET, 4 allée Emile Monso, 31030 Toulouse Cedex 4 (France); Lafont, Marie-Christine [Institut CARNOT, CIRIMAT-ENSIACET, 4 allée Emile Monso, 31030 Toulouse Cedex 4 (France); Tanguy, Benoit [CEA Saclay, DEN/DANS/DMN/SEMI, 91191 Gif-sur-Yvette Cedex (France); Andrieu, Eric [Institut CARNOT, CIRIMAT-ENSIACET, 4 allée Emile Monso, 31030 Toulouse Cedex 4 (France)

    2013-02-15

    The sensitivity of precipitation-strengthened A286 austenitic stainless steel to stress corrosion cracking was studied by means of slow-strain-rate tests. First, alloy cold working by low cycle fatigue (LCF) was investigated. Fatigue tests under plastic strain control were performed at different strain levels (Δε{sub p}/2 = 0.2%, 0.5%, 0.8% and 2%) to establish correlations between stress softening and the deformation microstructure resulting from the LCF tests. Deformed microstructures were identified through TEM investigations. The interaction between oxidation and localized deformation bands was also studied and it resulted that localized deformation bands are not preferential oxide growth channels. The pre-cycling of the alloy did not modify its oxidation behaviour. However, intergranular oxidation in the subsurface under the oxide layer formed after exposure to PWR primary water was shown.

  6. Phase transformation and cooling curves of the mild steel influenced by previous hot rolling

    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.

  7. Influence of thermal aging on the reactivity of duplex stainless steel surfaces

    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.

  8. Influence of Sample Pretreatment Methods on the Determination of Trace Oxygen in Iron and Steel

    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.

  9. Influence of localized plasticity on oxidation behaviour of austenitic stainless steels under primary water reactor

    The sensitivity of precipitation-strengthened A286 austenitic stainless steel to stress corrosion cracking was studied by means of slow-strain-rate tests. First, alloy cold working by low cycle fatigue (LCF) was investigated. Fatigue tests under plastic strain control were performed at different strain levels (Δεp/2 = 0.2%, 0.5%, 0.8% and 2%) to establish correlations between stress softening and the deformation microstructure resulting from the LCF tests. Deformed microstructures were identified through TEM investigations. The interaction between oxidation and localized deformation bands was also studied and it resulted that localized deformation bands are not preferential oxide growth channels. The pre-cycling of the alloy did not modify its oxidation behaviour. However, intergranular oxidation in the subsurface under the oxide layer formed after exposure to PWR primary water was shown

  10. INFLUENCE OF COLD ROLLING TECHNOLOGY ON TEXTURE EVOLUTION OF IF STEEL

    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.

  11. Influence of Heat Treatment on Mercury Cavitation Resistance of Surface Hardened 316LN Stainless Steel

    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.

  12. Influence of the austenitic stainless steel microstructure on the void swelling under ion irradiation

    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.

  13. The influence of drawing parameters on the properties high-manganese TWIP steel wires

    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.

  14. Shielding gas influences on laser weldability of tailored blanks of advanced automotive steels

    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.

  15. Shielding gas influences on laser weldability of tailored blanks of advanced automotive steels

    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.

  16. Influence of Gas Flow Rate on the Deposition Rate on Stainless Steel 202 Substrates

    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.

  17. Thermal fatigue of austenitic stainless steel: influence of surface conditions through a multi-scale approach

    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)

  18. Influence of carbon content on properties of carburized steel using different quenchants

    The problem of creating on of case and core structure and properties of carburized and hardened elements is still present. The analysis of literature showed that using the polymer quenching media to hardened carburized parts with structure martensite-retained austenite, as carbides-martensite - retained austenite is still not known very well. Using as a quenching medium of hardened, water polymer solution let through changing the capacity polymer in solution, circulation and temperature cooling media by watering changes its cooling abilities and let the uniformity of the quenching process. The quenching of elements in water let very often to distortion of brakes of the hardened elements after the carburized and quenching in the oil cannot give these elements the right core structure. In the present work the structure and choice of properties of hardened carburized layers were introduced for chromium and chromium-manganese steel after gas carburizing process (850oC/1-10 h) and direct hardening (center cooling: water polymer solution-polyglycol oxyalkylen) and tempering. The results of investigations permitted of affirm that layer with structure martensite - retained austenite and carbides - martensite - retained austenite produced in process of hardening with polymer solution applying as quenchant give profitable hardness of the element and impact strength of the element with the right layer thickness, the right hardness and microhardness as well as changes in microhardness on section in comparison to layers produced during cooling in water or oil. The results of the mechanical properties of hardened carburized layers created on the chromium-manganese and chromium steels do not show significant differences. (author)

  19. 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

    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.

  20. Influencing parameters of crack initiation and crack growth in low-alloy fine-grained structural steels in high-temperature water

    Reactor pressure vessel steels of the types 22NiMoCr37 and 20MnMoNi5 5 were tested. The corrosive medium depended on the type of power plant. Deionate with 0.2 ppm O2 was used for a boiling-water reactor and for conventional power plants. A medium with a very low content of O2 was used for pressurized-water reactor tests. Great influence on corrosion-initiated crack growth have the following factors: a) the flow rate of the medium, b) the medium's content of SO42- and of O2, and c) the sulphur content of the steel. (MM)

  1. Influence of cubic texture intensity of hot rolled ferritic non-oriented electrical steels on the microstructure and texture in the final processed material

    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.

  2. Bainite transformation of low carbon Mn-Si TRIP-assisted multiphase steels: influence of silicon content on cementite precipitation and austenite retention

    Studies dealing with TRIP-assisted multiphase steels have emphasized the crucial role of the bainite transformation of silicon-rich intercritical austenite in the achievement of a good combination of strength and ductility. The present work deals with the bainite transformation in two steels differing in their silicon content. It is shown that both carbon enrichment of residual austenite and cementite precipitation influences the kinetics of the bainite transformation. A minimum silicon content is found to be necessary in order to prevent cementite precipitation from austenite during the formation of bainitic ferrite in such a way as to allow stabilisation of austenite by carbon enrichment. (orig.)

  3. Influence of additional alloying with nitrogen on structure and properties of high chromium steel Kh17 after hot rolling

    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

  4. Influence of localized plasticity on Stress Corrosion Cracking of austenitic stainless steel. Application to IASCC of internals reactor core vessels

    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

  5. Key factors influencing the stability of silane solution during long-term surface treatment on carbon steel

    Highlights: •The corrosion-resistance time of silane films decreases with increasing cycle numbers. •The morphology of silane films prepared from aged solution is inhomogeneous. •Introduction of contamination ions is one reason for the poor property of aged solution. •Consumption of silane is the other reason for the poor property of aged solution. •Fe3+ accumulated is the key factor influencing the property of silane solution. -- Abstract: The mixtures of bis-[trimethoxysilylpropyl]amine and vinyltriacetoxysilane were used for surface treatment of carbon steel, aiming to investigate the factors influencing the stability of silane solution during long-term experiment from two aspects. One is the concentrations of contamination ions, and the other is mass of silane consumed per cycle which is calculated according to concentration of Si measured by silicon molybdenum blue photometry. The results indicate that the accumulation of contamination ions, especially Fe3+, is the main factor leading to the condensation between the Si–OH groups in silane solution, which is responsible for the downward stability of silane solution

  6. Influence of nickel additions on the corrosion behaviour of low nitrogen 22% Cr series duplex stainless steels

    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.

  7. Influence of nickel additions on the corrosion behaviour of low nitrogen 22% Cr series duplex stainless steels

    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

  8. Update of the water chemistry effect on the flow-accelerated corrosion rate of carbon steel: influence of hydrazine, boric acid, ammonia, morpholine and ethanolamine

    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)

  9. Influence of delta ferrite content and welding variables on notch toughness of austenitic stainless steel weldments

    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

  10. Influence of Workpiece Material on Tool Wear Performance and Tribofilm Formation in Machining Hardened Steel

    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.

  11. Influence of reverted austenite on the texture and magnetic properties of 350 maraging steel

    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.

  12. The influence of strain rate on the microstructure transition of 304 stainless steel

    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 (10-105 s-1). Based on comprehensive analysis of X-ray diffraction and electron microscopy observations, we found that the strain rate between 10 and 103 s-1 only activated dislocation motions and α'-martensite transformations, resulting in nanocrystallines and ultra-fine grains. However, higher strain rates (104-105 s-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 α'-martensite transformations.

  13. Influence of Surface Nano-structured Treatment on Pack Boriding of H13 Steel

    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.

  14. Influence of reverted austenite on the texture and magnetic properties of 350 maraging steel

    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 (Ms) 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

  15. Influence of Y on microstructures and mechanical properties of high strength steel weld metal

    Highlights: • The loss of yttrium oxide very low when it transited from welding materials to weld metal deposits. • The yttrium element could refine and spheroidize inclusions, and the nucleation of acicular ferrites would be promoted. • Proper yttrium oxide could reduce the content of diffusible hydrogen in weld metal deposits. • Mechanical properties such as tensile strength and low-temperature toughness were acceptable. - Abstract: A comprehensive investigation is conducted into the effect of yttrium oxide on microstructures of weld metal deposits and mechanical properties of high strength steel electrode measured in the Ni–Cr–Mo–V alloy system. The results demonstrate a gradual decrease of the content of proeutectoid ferrites and a gradual increase of acicular ferrites, as the content of yttrium oxide increases from 0% to 0.02%. However, as the content of yttrium oxide surpasses 0.02%, the content of acicular ferrites reduces significantly. Meanwhile, the toughness under low-temperature impact increases and then decreases, as the content of yttrium varies from 0% to 0.03%, reaching the maximum of 102J at the field of 0.02%. However, the strength fails to change significantly. The results also indicate that the cold cracking sensitivity is lower when the content of yttrium oxide is 0.02%, but the values would increase as the content of yttrium oxide fluctuates

  16. Recrystallization in ultra low carbon (ULC) steel: influence of the as-deformed microstructure and texture

    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.

  17. Extrinsic Influence of Environment-Induced Degradation on Load Carrying Capacity of Steel Beams

    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.

  18. Influence of weld discontinuities on strain controlled fatigue behavior of 308 stainless steel weld metal

    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

  19. Moessbauer spectroscopy of corrosion products of mild steel due to microbiologically influenced corrosion

    Corrosion products of mild steel exposed to four different cultures of sulfur reducing bacteria (SRB) grown in a synthetic medium have been studied by transmission Moessbauer spectroscopy (TMS). Cultures of SRB studied are two hydrogenase positive strains, Desulfovibrio desulfuricans (DD) and Desulfovibrio vulgaris (DV) and two hydrogenase negative strains Desulfotomaculum orientis (DO) and Desulfotomaculum nigrificans (DN). The corrosion products generated on the coupons as well as in the broth were studied. In all the cases, the corrosion products removed from coupons showed the presence of green rust 2 (GR2), ferrous sulfides, γ-FeOOH and superparamagnetic (SPM) α-FeOOH in different proportions. The corrosion products from the broth showed a symmetrical central doublet, which indicates the presence of γ-FeOOH and SPM α-FeOOH along with ferrous sulfides. The corrosion products from coupons suspended in sewage water also showed the presence of GR 2 and ferrous sulfides together with oxyhydroxides. FTIR spectrum supports the presence of these phases in corrosion products. The formation of GR 2 on coupons seems to be the first step for the SRB induced corrosion. The corrosion rate has been found in the order of DO > DN > DV > DD. (author)

  20. Influence of stress on creep deformation properties of 9-12Cr ferritic creep resistant steels

    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.)