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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. 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.

  3. 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.)

  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. 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...

  19. 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.

  20. 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.

  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 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.

  6. 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)

  7. 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)

  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. 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)

  15. 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.

  16. 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.

  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 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 ...

  2. 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...

  3. 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...

  4. 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 ...

  5. 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....

  6. 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 ...

  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. 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.

  19. 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

  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. 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.

  6. 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...

  7. 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.

  8. 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.

  9. 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.)

  10. 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)

  11. 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...

  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. 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...

  14. 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)

  15. 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.

  16. 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

  17. 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

  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. 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.

  6. 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

  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

    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.

  15. 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

  16. 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

  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. 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.

  20. 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

  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. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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

  14. 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.

  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. 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.

  4. 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)

  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 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

  7. 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.

  8. 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.

  9. 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.

  10. 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)

  11. 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.

  12. 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)

  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. 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.

  16. 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.

  17. 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)

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. 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)

  8. 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

  9. 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...

  10. 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.

  11. 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

  12. 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.

  13. 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)

  14. 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

  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 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

  4. 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

  5. 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.

  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. 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.

  9. 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.

  10. 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.

  11. 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

  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. 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...

  20. 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)

  1. 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.

  2. 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.)

  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. 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)

  11. 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.

  12. 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

  13. 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.

  14. 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)

  15. 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.

  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 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.

  18. 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

  19. 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.)

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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)

  6. 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.)

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  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 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

  15. 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.

  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.