Academic literature on the topic 'Ferritic steel Metallography'
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Journal articles on the topic "Ferritic steel Metallography"
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Anisovich, A. G. "Measurement of Steel Structure Elements in the Specialized Module of the IMAGE-SP Image Processing Software." Devices and Methods of Measurements 11, no. 4 (December 17, 2020): 279–88. http://dx.doi.org/10.21122/2220-9506-2020-11-4-279-288.
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Grain size is one of the most important characteristics of the microstructure of metals and alloys. Determination of the grain size of steel is regulated by Standart 5639-82 "Steels and alloys. Methods for detection and determination of the grain size". Standart includes determining the grain score by comparison with reference scales, as well as manual measurement methods. The use of image processing software opens up new opportunities for the materials analysis, including for the quantitative metallographic analysis of steels and alloys. The purpose of this work was to test the specialized "Metallography" module to determine the grain score of the image processing software "IMAGE – SP", as well as to check the reliability of the obtained results using the example of ferritic and austenitic steels.In the "Metallography" module, the analysis of standard images of annex No. 3 of Standart 5639-82, as well as real images of the structures of ferritic and austenitic steel, is carried out. It is shown that the results correspond to the definition of the Standart grain score. The divergence in the results is 1 point, which is acceptable.The active development of software products for the quantitative analysis of images in metallography will make it possible to legitimize the methods of computer measurement of parameters of the structures of metals and alloys by creating appropriate standards. Successful testing of the specialized "Metallography" module demonstrates opportunities and prospects for further development of specialized software products for measuring quantitative values of metal and alloy structures. The active development of software for quantitative analysis of the images in metallography will make it possible to legalize methods for measuring parameters of metal and alloy structures by computer techniques.
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Arumugham Akilan, Arulselvan, Ravi K. Enneti, Vamsi Krishna Balla, and Sundar V. Atre. "Effects of Hot Isostatic Pressing on the Properties of Laser-Powder Bed Fusion Fabricated Water Atomized 25Cr7Ni Stainless Steel." Lubricants 10, no. 12 (December 1, 2022): 340. http://dx.doi.org/10.3390/lubricants10120340.
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25Cr7Ni stainless steel (super duplex stainless steels) exhibits a duplex microstructure of ferrite and austenite, resulting in an excellent combination of high strength and corrosion resistance. However, Laser-Powder Bed Fusion fabrication of a water-atomized 25Cr7Ni stainless steel of novel chemical composition resulted in a purely ferritic microstructure and over 5% porosity. The current study investigated the effects of two hot isostatic pressing parameters on the physical, mechanical, and corrosion properties as well as microstructures of water-atomized 25Cr7Ni stainless steel of novel composition fabricated by L-PBF for the first time in the literature. The corrosion behaviour was studied using linear sweep voltammetry in a 3.5% NaCl solution. The Hot Isostatic Pressing-treated sample achieved over 98% densification with a corresponding reduction in porosity to less than 0.1% and about 3~4% in annihilation of dislocation density. A duplex microstructure of ferrite 60% and austenite 40%was observed in the X-Ray Diffraction and etched metallography of the HIP-treated samples from a purely ferritic microstructure prior to the HIP treatment. With the evolution of austenite phase, the HIP-treated samples recorded a decrease in Ultimate Tensile Strength, yield strength, and hardness in comparison with as-printed samples. The variation in the morphology of the evolved austenite grains in the HIP-treated samples was observed to have a significant effect on the elongation. With a reduction in porosity and the evolution of the austenite phase, the HIP-treated samples showed a higher corrosion resistance in comparison with the as-printed samples.
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Wen, Yu Ren, Yong Liu, Dong Hua Liu, and Bei Tang. "Preparation and Thermal Stability of a Mechanically Alloyed Oxide Dispersion Strengthened Ferritic Steels." Materials Science Forum 715-716 (April 2012): 605–10. http://dx.doi.org/10.4028/www.scientific.net/msf.715-716.605.
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Oxide dispersion strengthened ferritic steels (so-called nanostructured ferritic alloys, NFAs), which are candidate structural materials in next generation nuclear power plant, have attracted much attention during recent years. In this work, iron oxide as oxygen carrier and titanium, yttrium hydrides were together mechanically milled with Fe-14Cr-3W gas-atomized powder. The thermal stability and recrystallization behaviour of the as-milled ferritic powder were studied by means of metallography, SEM, TEM and microhardness test. After ball milling for 48h, complete solid solution of bcc-Fe was formed in the as-milled powder. The thermal analysis results show that dispersed oxides with an average diameter of 5nm precipitate from the supersaturated matrix at about 850 °C. During annealing at temperatures from 800 to 1000 °C, a large number of equiaxed grains as fine as few hundreds of microns were found embedding in the matrix; the recrystallized grains stay quite stable and show minor dependence on annealing temperature and time. After being heated to 1200 °C for extended time, abnormal grain growth took place and resulted in bimodal grained structure. The effect of secondary particles on the thermal stability and recrystallization behavior of the ferritic steel was also discussed.
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Doomra, Akash, Sandeep Singh Sandhu, and Beant Singh. "Effect of post weld heat treatment on metallurgical and mechanical properties of electron beam welded AISI 409 ferritic steel." Metallurgical and Materials Engineering 26, no. 3 (September 30, 2020): 279–92. http://dx.doi.org/10.30544/545.
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The applicability of ferritic stainless steel is restricted due to its low weldability, and this can be attributed to the severe grain growth in the weld zone during the solidification of the weld pool and formation of fully ferritic structure. This study aims to investigate the weldability of 18 mm thick AISI 409 ferritic stainless steel plates using an electron beam welding process without the use of filler metal. The joints were investigated for metallography characterization (microstructure, macrostructure, and microhardness) and mechanical behavior (tensile strength and impact toughness) in as-welded condition and after post-weld heat treatment at 550 ºC for 75 minutes. The weld zone exhibited large columnar grains in the direction perpendicular to the weld centerline and got refined after post-weld heat treatment. The ultimate tensile strength, yield strength, and microhardness of the weld zone were found higher than the base metal. The impact toughness of weld zone was found to be reduced by 45%, but the post-weld heat treatment improved the toughness by 40%. Results revealed that the electron beam welding process could be successfully employed for welding of AISI 409 ferritic stainless steel, which will increase its application range that requires thicker section of welded plates. Post-weld heat treatment was found to be advantageous for improving the microstructure and mechanical properties.
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Pei, Yu, Zhe Gao, Yi Liu, Shi Qian Zhao, Chang Yu Xu, Li Yong Ren, and Xing Liang Li. "Continuous Cooling Transformation Behavior and the Phase Transformation Model in Low Carbon High Strength Sheet Steel." Advanced Materials Research 1035 (October 2014): 27–35. http://dx.doi.org/10.4028/www.scientific.net/amr.1035.27.
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Phase transformation of austenite continuous cooling process in low carbon high strength sheet steel has been researched by DIL805 thermal mechanical simulate. The Austenite continuous cooling transformation (CCT) diagram of steel has been determined by dilatometry and metallography. With the increase of cooling rate, ferritic transformation, perlitic transformation, bainite transformation and martensitic transformation have produced in the organization. Mathematical equations of phase transformation point-cooling rate and phase variable-cooling rate have been established and phase transformation model of high fit degree has been gained by regression calculation. The results show that calculated value and experimental value are nearly similar, so the phase transformation model is feasible.
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Guo, Jin, Shui Ping Hu, Zhen Li Mi, and Dong Bin Zhang. "Effect of Different Cooling Paths on the Microstructure and Properties of a Plain Carbon Steel." Materials Science Forum 762 (July 2013): 171–75. http://dx.doi.org/10.4028/www.scientific.net/msf.762.171.
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The effect of different cooling paths on the microstructure and properties of a plain carbon steel was carefully investigated by thermal simulation, hot rolling, tensile tests and quantitative metallography. Experimental results indicate that the more rapid the cooling rate is, the smaller the average ferritic grain size is and the higher the mechanical properties are. Both ultra fast cooling method and ultra fast cooling+accelerated controlled cooling method could refine grain size and improve mechanical properties. Without any alloy addition, using the ultra fast cooling immediately after hot rolling process, the yield strength of the plain carbon steel could reach 360 MPa and the elongation is 32%.
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Subramanian, Chidambaram. "Experimental in-situ metallographic investigations of industrial hydrocarbon processed fired heater tubes." Metallurgical Research & Technology 116, no. 2 (2019): 203. http://dx.doi.org/10.1051/metal/2018062.
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In the present investigations, the coker unit heater tube has been evaluated using in-situ metallography, after an exposure at a temperature of 615 °C for around 52 000 h. The heater tubes in petroleum industries are mostly damaged by creep failures; hence metallography assessments are conducted for safe operation of industrial units. The primary material of construction for fired heater tubes is ASTM A213 GrT9 chromium molybdenum ferritic steel and maximum primary creep strains are estimated as 11.2761 × 10−2 and 11.2802 × 10−2 for temperature 888 and 923 K, respectively. In-situ metallography test was conducted at finish pass surface on one butt weld joint section of two different passes (pass I and pass II) of heater tubes. Hardness is within limit and chemical composition stands confirmed within material standards. A heater tube weld joint comprising weldment metal, heat affected zone and base metal were found in good condition, and no indications of creep were observed. Tempered martensite is observed only in weld metal and heat affected zone which aids in high temperature creep strength of metal at weld joint and heat affected zone. No martensitic structure was observed on the base metal; however base metal creep strength was ascertained by fine precipitated alloy carbides within the ferritic matrix base metal structure. Recommendations were further provided to monitor the performance of heater tubes and for an early prediction of secondary creep.
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Lhabitant, Solène, Alain Toufine, and Anis Hor. "Heat Treatments of P295GH Steel Made by Directed Energy Deposition: Metallography and Hardness." Materials Science Forum 1046 (September 22, 2021): 65–70. http://dx.doi.org/10.4028/www.scientific.net/msf.1046.65.
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Directed energy deposition (DED) is an Additive Manufacturing process deposing fused metal powder on a preexisting substrate. This document shows the influence of heat treatment on P295GH deposit made by DED, for hybridization process. The heat treatment must reduce the macroscopic differences between the rolled substrate and the deposited DED material. The experimental plan has been defined around AC3 temperature, according to P295GH existing literature. XRD analysis, hardness measurements and metallographic inspections have been performed on samples before and after heat treatment. XRD analysis and hardness measurements have shown an isotropic material. The as-built microstructure is ferritic and acicular, but coarsens after the heat treatment. The study promotes a heat treatment at 800°C during 3 hours to obtain the best compromise between properties, impact on the substrate and differences with the rolled substrate.
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Costa Viana, Carlos Sergio da, F. S. Candido, and Andre Luiz Pinto. "An EBSD Analysis of the Origins of Ridging in AISI 430 Steel Sheets." Materials Science Forum 495-497 (September 2005): 173–78. http://dx.doi.org/10.4028/www.scientific.net/msf.495-497.173.
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In the present work the characterisation of both the microstructure and the microtexture of two ferritic stainless steel sheets - AISI 430 (Fe17% Cr) and AISI 434 (17% Cr, 1% Mo) - known to display different ridging behaviours, was carried out by optical metallography, EBSD and OIM techniques. It was concluded that severe ridging is a consequence of: (a) presence of {111}<uvw> and {001}<uvw> colonies of grains alternating throughout the sheet plane; (b) through thickness texture inhomogeneity with layers of {001}<110> oriented large grains of low Rvalues sandwiched between layers of higher R-value textured material.
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Liang, Xiao Jun, Ming Jian Hua, C. Isaac Garcia, and Anthony J. DeArdo. "The Thermomechanical Controlled Processing of High-Strength Steel Plate: A New View of Toughness Based on Modern Metallography." Materials Science Forum 762 (July 2013): 38–46. http://dx.doi.org/10.4028/www.scientific.net/msf.762.38.
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Modern thermomechanical controlled processing (TMCP) of advanced steels is now an important processing route in the production of engineering structures and products that are of value to society. The principles of TMCP are now practiced in the hot mill, cold mill and press forming shops around the world. Successful TMCP means that the proper metallurgical microstructure has been obtained in the required areas of the steel. The ideal microstructure is often defined by the correct phase balance and dimensions either of the parent austenite or final ferritic phase. Technological and economic demands have led to ever increasing levels of strength, especially for applications such as large diameter linepipe. The operative yield strengths in 18mm hot rolled plate have increased from X52(ferrite pearlite) in 1970 to X80(ferrite-bainite) today. The next frontier is the X100-X120 strength range, where bainitic or martensitic microstructures are required. It is clear that achieving a high-strength bainitic microstructure in heavy plate requires a high Carbon Equivalent value (C. E. II or Pcm), a rapid cooling rate, and a low water-end temperature. The requirement of high toughness and good weldability also means a low carbon content. This paper will describe the results of a research program where a steel of C. E. 0.56 and Pcm 0.23 was reheated, rough rolled for grain refinement, finish rolled for austenite pancaking, and direct quenched to below the Bs temperature. It was found that the strength and especially the toughness of the fully processed plates could not be explained using conventional metallographic techniques in conjunction with known structure-property relationships. However, the application of modern metallographic techniques based on FEG-SEM incorporating OIM led to microstructural characterization that more fully explained the observed mechanical properties. Of particular importance were the amount of MA micro-constituent, the crystallographic packet size of the bainite, and the high angle boundary character, especially the CSL boundaries, found in the microstructure. In the future, improved modeling of microstructural evolution and attendant mechanical properties will incorporate these important features.
Dissertations / Theses on the topic "Ferritic steel Metallography"
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Smith, Gillian. "Modelling fracture in ferritic steel." Thesis, University of Surrey, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250880.
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Benchouieb, Rachid. "Effect of multi-pass hot rolling on recrystallisation behaviour of ferritic stainless steel." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389668.
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Mahmoody, Sam. "Micromechancal modeling of dual-phase steel using a rate-dependent crystal plasticity model." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99778.
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Dual-phase (DP) steels consisting of a ferrite matrix with dispersed martensite particles have attracted a significant interest due to their combination of high work hardening and ductility. A great deal of experimental work has been done to obtain a better comprehension of the relation of their mechanical behaviour to their microstructural characteristics. In the present work, a micromechanical study of ferrite-martensite DP steels is conducted. The deformation of ferrite is described by a rate-dependent crystal plasticity theory, which relates the stress-strain field equations on the grain level to the macroscopic behaviour of the material. The crystal plasticity theory assumes that slip is the only deformation mechanism. Martensite, on the other hand, is considered an elastic-plastic isotropic solid. The interfaces of the grains are taken into account through an idealized form of grain boundaries. A FORTRAN program was coupled with the finite element method to solve the stress equations of the crystal plasticity. Including the grain boundaries made it possible to examine the effect of ferrite grain size on the strength of the material. It is shown that by decreasing the grain size, the yield stress increases according to Hall-Petch equation. Additionally, the effects of the volume fraction of martensite (Vm) on the onset strain, i.e. the strain at which martensite deforms plastically, and of the distribution of martensite on the stress are studied. The former showed that the onset strain of the DP steel declines linearly with increasing Vm up to 36%, beyond which the onset strain becomes independent of V m. The latter revealed that when martensite particles are formed as islands in the ferrite grains, the material exhibits higher strength and hardening rate; compared to when martensite is distributed as large blocks among the ferrite grains.
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Sierra, Robinson. "Investigation of the mechanical behaviour of TRIP steels using FEM." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99793.
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The need to develop light-weight and high strength materials for car frames which improve fuel efficiency and provide increased passenger safety during dynamic events such as automobile crashes has been the focus of the steel and automobile industries for the past 30 years. In recent years, the development of high strength steels such as multi-phase TRIP (Transformation-Induced Plasticity)-aided steels have shown great promise due to their excellent combination of high strength and ductility. The savings in automobile weight is provided by the inherent strength of TRIP steels which allows for the use of thinner sections. The TRIP effect is characterized by the phenomenon known as strain-induced martensitic transformation (SIMT) which enhances the work hardenability of such steels as the austenite phase transforms to the much harder martensite phase during plastic straining. This results in a resistance to local necking which subsequently enhances the strength, ductility, and formability of such steels. However, various factors exist which affect the mechanical behaviour of TRIP steels. This study will aim, through the use of finite element models, to investigate the role and influence of each of these factors on the TRIP effect in type 304 austenitic and multi-phase TRIP steels. These factors include the rate at which the martensitic transformation proceeds, the state of stress to which the material is subjected to, the interaction between the surrounding matrix and embedded retained austenite islands in multi-phase TRIP steels, and the volume fraction and morphology of the retained austenite islands. Investigation of these factors will provide further insight on each of their contributions to the TRIP effect in order to exploit the potential benefits offered by these steels.
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Morgan, Terence S. "Microstructural effects of neutron irradiation on ferritic/martensitic stainless steels." Thesis, Loughborough University, 1992. https://dspace.lboro.ac.uk/2134/13768.
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A commercial grade 12%CrMo VNb ferritic/martensitic stainless steel in the form of parent plate and high-nickel off-normal weld material has been fast neutron irradiated to equivalent damage levels of 33 and 50 dpa at 400 and 465°C respectively. The microstructural and microchemical changes induced in the irradiated material, together with as-tempered and thermal control material, have been determined to high resolution by conventional transmission electron microscopy and the use of a field emission gun scanning transmission electron microscope (FEGSTEM). Equilibrium (co )segregation of chromium, molybdenum and phosphorus was detected at boundary planes in thermally aged material, with greater enrichment at the higher ageing temperature. The relative magnitudes of apparent phosphorus segregation at the two temperatures were in accordance with McLean's model governing the kinetic approach to equilibrium. The electron probe I segregant interaction was modelled in an attempt to deconvolute true segregant concentrations from derived concentration profiles: these 'deconvoluted' concentrations approximated those predicted by McLean's model. The net effects of irradiation on parent plate interfacial microchemistry were found to be to: (i) inhibit the (co )segregation of chromium, molybdenum and phosphorus, (ii) cause chromium depletion from adjacent to boundary planes, (iii) cause enrichment of silicon at prior austenite and lath boundaries during irradiation at 400°C and (iv) cause enrichment of nickel at lath boundary planes only, at both temperatures. The radiationinduced precipitates ~C and G phase, both nickel- and silicon-rich, were observed. The fully martensitic off-normal weld metal transformed to a duplex austenite!ferrite structure during irradiation at 465°C; in contrast the thermal control was at least metastable. The transformation was thought to be a martensitic reversion, facilitated by radiation-generated dislocation loops acting as nucleation sites. The austenite was heavily voided (-15 vol.%); the ferrite was relatively void-free. Depletion of the oversized solutes chromium, manganese and molybdenum and enrichment of nickel, silicon, aluminium and traces of titanium were detected at void interfaces in the austenite: little segregation could be discerned at voids in the ferrite. Overall, the results within this work and in comparison to previous studies highlight the sensitivity to initial composition, microstructure and heat treatment that the 12%Cr ferritic/martensitic steels display in their response to irradiation.
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Essadiqi, E. "Effect of deformation on the [gamma] to [alpha] transformation in three microalloyed steels." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74008.
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Saied, Mahmoud. "Experimental and numerical modeling of the dissolution of delta ferrite in the Fe-Cr-Ni system : application to the austenitic stainless steels." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI016/document.
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La ferrite résiduelle δ est présente dans les microstructures de coulée des aciers inoxydables austénitiques. Elle résulte de la transformation incomplète δ→γ ayant lieu l'étape de solidification. Sa présence peut nuire à la forgeabilité à chaud des aciers inoxydables et peut conduire à la formation de criques de rives et de pailles en J lors du laminage à chaud des brames. Ce travail de thèse a pour but de comprendre les mécanismes de la transformation δ→γ à haute température dans les aciers inoxydables austénitiques via une modélisation expérimentale et numérique. La transformation a été étudié dans un alliage ternaire Fe-Cr-Ni coulé par lingot et de composition proche de celle des alliages industriels. Trois morphologies de ferrite ont été mises en évidence à l'état brut de solidification: lattes au bord du lingot, vermiculaire et lattes au centre. Leur cinétique de dissolution est étudiée à des températures allant de 1140°C à 1340°C et caractérisée en termes de fraction de ferrite et profils de composition du Cr et du Ni. La dissolution de la ferrite vermiculaire comprend trois étapes : une croissance initiale transitoire suivie par deux régimes de dissolution à haute puis à faible taux de transformation. D'un autre côté, il a été possible d'étudier la dissolution de la ferrite dans des microstructures multicouches élaborées par l'empilement de plaques de ferrite et d'austénite du système Fe-Cr-Ni et soudées à l'état solide par Compression Isostatique à Chaud puis réduits en épaisseurs par laminages successifs. L'étude et la caractérisation de la cinétique de dissolution de la ferrite est plus facile dans ces microstructures étant donnée la planéité initiale des interfaces δ/γ. L'analyse des résultats expérimentaux a été menée via le développement d'un modèle numérique, à interface mobile, de la transformation de phases δ→γ pilotée par la diffusion. La diffusion peut être traitée dans les géométries plane, cylindrique et sphérique. En guise de validation, le modèle a été utilisé pour analyser la dissolution de la ferrite dans les microstructures multicouches. Par la suite il a été appliqué au cas de la ferrite vermiculaire en usant d'une approche novatrice où la morphologie des dendrites est approximée par une combinaison de cylindres et de sphères. Malgré la simplicité des hypothèse sous-jacentes, le modèle a permis d'expliquer les mécanismes de croissance initiale et de changement de régime de dissolution. D'autre part, via une étude paramétrique, l'effet des données d'entrée a été étudié et les plus pertinentes d'entre eux en termes de prédiction quantitative ont été mises en avant, en particulier la description thermodynamique du digramme Fe-Cr-Ni, le gradient initial et la distribution des rayons des particules de ferriteResidual δ-ferrite is widely encountered in the as-cast microstructure of austenitic stainless steels. It stems from the incomplete high temperature solid-state δ→γ transformation occurring upon the solidification stage. Its presence has a detrimental effect the hot workability of stainless steels, leading to the formation of edge cracks and sliver defects during slabs hot rolling. This PhD work aims at bringing more understanding of the kinetics of high temperature δ→γ transformation in austenitic stainless steels via experimental and numerical modeling. The transformation was studied in a ternary Fe-Cr-Ni ingot-cast alloy with composition close to the industrial alloys. Three ferrite morphologies were identified: lathy at the edge of the ingot, vermicular and lathy at the center. Their dissolution kinetics were established at temperatures ranging from 1140°C to 1340°C and characterized in terms of ferrite fraction and Cr and Ni diffusion. The vermicular ferrite undergoes a transient growth followed by a high then a low rate dissolution regimes. On the other hand, ferrite dissolution was also studied in the multilayered microstructures. such microstructures were elaborated by alternating ferrite and austenite sheets of the Fe-Cr-Ni system, diffusion-bonded by Hot isostatic Pressing and reduced in thickness by successive rollings. Dissolution is easier to handle in such microstructures thanks to the initial planar δ/γ interfaces. Analysis of the experimental results were carried out with a numerical moving-boundary model of diffusion-controlled δ→γ transformation. Diffusion can be treated in the planar, cylindrical and spherical geometries. As a preliminary validation, the model was used to analyze kinetics of ferrite dissolution in the multilayered microstructures. It was then applied to the cast alloy using an original descriptive approach combining spheres and cylinders as equivalent morphology of dendritic ferrite. Although based on simplifying assumptions, the model was able to reproduce experimental results with satisfactory agreement. Mechanisms underlying the initial growth of vermicular ferrite and the transition in dissolution regimes were outlined. The effect of a wide range of input parameters has been considered and relevant parameters for quantitative calculations were brought to light, such as thermodynamical descriptions of the Fe-Cr-Ni system, composition gradients and distribution of ferrite's radii
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Pappas, Adlreburg Nickolas. "To Make Iron of Iron : A Comprehensive Analytical Study of Spade Shaped Iron Bars." Thesis, Stockholms universitet, Arkeologiska forskningslaboratoriet, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-145694.
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This thesis aims to provide adequate analytical information on the spade shaped iron bars of Norrland and central Sweden. While their significance has been thoroughly debated for decades, analytical research on them has been confined to cases of single artefacts or theoretical interpretations of their value, meaning and origin. In this study a comprehensive approach is taken into consideration. Based on X-Ray fluorescence (XRF), scanning electron microscopy (SEM) and metallographical analysis this thesis seeks to facilitate new interpretations on quality, production centres and usage based on analytical results. Aiming to settle some of the long lasting questions regarding the artefacts while producing results which can further the discussion by raising new questions, previously unasked.
Conference papers on the topic "Ferritic steel Metallography"
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Yescas, Miguel, Pierre Joly, and François Roch. "Thermal Aging Assessment and Microstructural Investigations of Alloy 52 Dissimilar Metal Welds for Nuclear Components." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93120.
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Abstract Dissimilar Metal Welds (DMW) are commonly found between the ferritic low alloy steel heavy section components and the austenitic stainless steel piping sections in nuclear power plants. In the EPR™ design which is the latest FRAMATOME Pressurized water reactor (PWR) these DMW involve a narrow gap technology with no buttering, and only one bead per layer of a nickel base alloy weld filler metal (Alloy 52). In order to assess the thermal aging performance of this relatively new narrow gap DMW design, a significant internal R&D program was launched some years ago. Several representative mock-ups were thoroughly characterized in the initial condition as well as in the thermal aged condition, up to 50,000 hours aging at 350°C. The characterisations were focused on the fusion line between the ferritic low alloy steel (LAS) and the nickel base alloy since a particular microstructure is present in this area, especially in the carbon depleted area of the Heat Affected Zone (HAZ) which is often regarded as the weak zone of the weld joint. Metallography, hardness, nanohardness, chemical analyses, and Atom Probe Tomography, as well as fracture toughness tests were carried out on different specimens in different thermal aging conditions. The results show that the fracture toughness behaviour in the ductile-brittle domain of the low alloy steel carbon depleted HAZ at the interface with the alloy 52 weld metal of the DMWs is excellent, even for a thermal ageing equivalent to 60 years at service temperature. This was found in spite of the carbon depleted zone of the HAZ, the variations of hardness, chemical composition, particularly the carbon gradients, and the thermal aging effect induced by phosphorous segregation at grain boundaries.
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Ruggieri, Claudio, and Andrey P. Jivkov. "A Local Approach to Assess Temperature Effects on Fracture Toughness Incorporating the Measured Distribution of Microcracks." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93186.
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Abstract This work describes a local approach to cleavage fracture (LAF) incorporating the statistics of microcracks to characterize the cleavage fracture toughness distribution in structural steels. Fracture toughness testing conducted on standard compact tension C(T) specimens for a 22NiMoCr37 pressure vessel steel provides the cleavage fracture resistance data needed to determine the measured toughness distribution. Metallographic examination of etched surfaces for the tested steel also provides the distribution of carbides, which are assumed as the Griffith fracture-initiating particles, dispersed in the material from which the cleavage fracture toughness distribution is predicted. Overall, the analyses conducted in the present work show that LAFs incorporating the statistics of microcracks are a viable engineering procedure to describe the dependence of fracture toughness on temperature in the DBT region for ferritic steels.
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Shao, Shanshan, Guodong Jia, Luowei Cao, and Guide Deng. "Research on Post-Fire Metallographic Structure and Hardness of Quenched and Tempered High Strength Steel 07MnMoVR." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93423.
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Abstract Quenched and tempered high strength steel 07MnMoVR provides an excellent combination of strength and toughness potentially providing significant cost savings in petrochemical industry. Exposure to fire will subject steel to thermal conditions that may alter the material’s microstructure and properties. The extent of the fire damage and the potential reusability of the components can be evaluated by fitness-for-service (FFS) assessment after a fire event. According to API 579-1/ASME FFS-1, metallurgical investigation and mechanical testing are the chief means for the assessment of fire damage. This paper presents the details of an experimental investigation on the post-fire metallographic structure and hardness of 07MnMoVR steel. Metallographic analyses and hardness testing were performed on coupons exposed to elevated temperatures varying from 550°C to 850°C for half an hour to 8 hours and then naturally cooled in air or cooled by water. The results show that the microstructure of as-received 07MnMoVR steel consisted of tempered sorbite and bainite. With increasing heat exposure temperature, bainite disappeared gradually. The recovery and recrystallization of ferrite began to occur after heat exposure at 650°C for 5hrs. When the heat exposure temperature exceeded 750°C, the effects of duration time and cooling rate on microstructure were both significant. A linear correlation is indicated by fitting the ultimate tensile strength and hardness. Due to the drastically degradation of impact toughness of 07MnMoVR steel after heat exposure exceeded 650°C, it is suggested that the removal and testing of material samples shall be utilized to evaluate the fire damage of components, besides replication or in-situ field metallography and hardness testing. This study can provide basis data and guidelines for the fitness-for-service assessment of 07MnMoVR steel suffered from a fire event.
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Stone, David J., Boian T. Alexandrov, and Jorge A. Penso. "Control of Retained Delta Ferrite in Type 410 Stainless Steel." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65543.
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Type 410 stainless steel is used in petro-chemical refineries for its high resistance to halide stress corrosion cracking, sulfide corrosion cracking, and sulfur attack at elevated temperatures. Along with its adequate corrosion resistance 410SS also exhibits low cost and hardenability making it an ideal material for hydro-processing applications. Problems related to meeting toughness and hardness code requirements within the weld metal and heat effected zone (HAZ) have been experienced during fabrication of 410SS welded components. The loss of toughness has been related to excessive amounts of delta ferrite in the weld metal and HAZ. The objective of this study was to quantify the effect of cooling rate and alloying compositions within ASTM and AWS specifications for 410SS on delta ferrite formation. C, Cr, Ni, and Mo, were used as factors in a model-based design of experiment (DOE) within CALPHAD based software DICTRA™ to simulate the effects of composition and cooling rate on delta ferrite formation. Based on the DOE results, a predictive model for quantification of retained delta ferrite in 410SS welds was developed along with evidence for cooling rate effect on retained delta ferrite. Optical metallography was also used to demonstrate possible ferrite content within the 410 composition range.
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Schroer, Carsten, and Juergen Konys. "Quantification of the Long-Term Performance of Steels T91 and 316L in Oxygen-Containing Flowing Lead-Bismuth Eutectic at 550°C." In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75770.
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The long-term performance of ferritic/martensitic steel T91 and austenitic 316L in oxygen-containing flowing lead-bismuth eutectic at 550°C was investigated by exposing the materials for up to 15000 h in the CORRIDA loop. The velocity of the liquid-metal flow was 2 m/s and the concentration of dissolved oxygen averaged 1.6×10−6 mass%. The resulting corrosion processes and products were analyzed and quantified using metallographic methods.
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Schroer, Carsten, Valentyn Tsisar, Olaf Wedemeyer, Aleksandr Skrypnik, and Jürgen Konys. "Corrosion in Steel T91 Caused by Flowing Lead–Bismuth Eutectic at 400°C and 10−7 Mass% Solved Oxygen." In 2016 24th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icone24-60845.
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Specimens produced from two different heats of ferritic/martensitic steel T91 were exposed to oxygen-containing flowing lead–bismuth eutectic (LBE) at 400 °C, 10−7 mass% solved oxygen and flow velocity of 2 m/s, for exposure times between around 1000 and 13,000 h. The occurring phenomena were analyzed and quantified using metallographic cross sections prepared after exposure. Oxidation causes a material loss of <10 μm after 13,000 h, while corrosion initiated by the solution of the steel elements may generally proceed around 15 to 30 μm deep into the material in the same amount of time. Oxide scales formed on both heats of T91 tend to buckle and detach. In the case of one of the investigated heats, a singular event of exceptionally severe solution-based corrosion was observed, with associated local material loss around 1.2 mm after 13,000 h. The results are compared especially with findings at 450 and 550 °C and otherwise similar conditions as well as austenitic steels tested in the identical experimental run.
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Mei-fang, Chen, Cao Sheng-qiang, and Tao Zhi-yong. "Study on Forging Cracks and Manufacturing Process of 022Cr19Ni10N Austenitic Stainless Steel Rod Travel Housing Forging for Control Rod Drive Mechanism." In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-67286.
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In order to gain high strength, fine grain size, stronger anti-corrosion property, and especially low permeability, the material 022Cr19Ni10N was chosen to manufacture the Rod Travel Housing Forging (RTHF) for Control Rod Drive Mechanism (CRDM). But, cracks were found in some forgings failing to meet the requirements of ultrasonic testing (UT). The causes of the forging cracks of this austenitic stainless steel forging were investigated by means of metallography, scanning electron microscopy (SEM) and other experimental methodology. The results indicated that the second δ-ferrite phase leads to the forging cracks between γ-δ interface during the low temperature forging process, and finally leads to the forging failure. It’s found that the cracks are distributing along the stripe δ-ferrite, and almost distributing in the same area as the large size δ-ferrite by metallography & SEM microstructure observation. The δ-ferrite is firstly found in the electroslag ingot, and in which, the distribution and size is different from the case to the core. The largest size δ-ferrite is around the core area, and this characteristic passes on to the final forging microstructure, although the shape, quantity & distribution of the δ-ferrite changed during the manufacturing process. Most forging cracks were found around the core area of the forging by UT examination. In the final forging process, when the forging temperature drops to 750∼850°C, the δ-ferrite have been forged to stripe shape and hundreds-micron size while the plasticity of the austenite reduce. What’s more, there are large hot plasticity differences between the δ-ferrite and the austenite, so the forging cracks initiate between γ-δ interface and extend to the area around to be a long crack in the low temperature forging process. In order to avoid the forging cracks in the Rod Travel Housing Forging, it’s necessary to reduce the content of δ-ferrite or improve the final forging temperature. Improving the final forging temperature, to guarantee the plasticity of the δ-ferrite and austenite, is another process to reduce the cracks. But while the temperature improves, the grain size grows rapidly, and may form mixed structure. So the most effective mean to reduce the content of δ-ferrite is to redesign the chemical components, mainly by increasing the nitrogen content from 0.06 (wt, %) to 0.12(wt, %), which makes the low temperature forging process for fine grain size possible. In the high-nitrogen-content forging, the δ-ferrite distributed sporadically and no δ-ferrite strip is found. By increasing the austenite forming elements (especially nitrogen), the cracks during low temperature forging process are avoided. What’s more, owning to the optimization of chemical compositions and manufacturing processes, the Rod Travel Housing Forging got fine grain size, low relative permeability, and good comprehensive mechanical properties with the ultimate tensile strength up to 570MPa.
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Huang, Zhijun, Kai Miao, Xiudi Cao, and Yutao Wang. "Experimental Study on High Performance Welding Materials for Pipeline Steels." In 2004 International Pipeline Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ipc2004-0611.
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West-to-East Natural Gas Transmission Project is in great need of high quality steels of API grade X70 and suitable high quality welding materials. The weld of pipe should have high strength, high toughness and low sulphur and arsenic contents (less than or equal to 0.005 wt % respectively). The work performed in WISCO concerning welding wires of SAW, GMAW and SMAW and weldability of pipe steel is reported in this article. Steel grade X70 is a TMCP high strength and high toughness steel with low carbon equivalent. It has good weldability and is less susceptible to cold cracking in the heat-affected zone. Generally in order for weld to gain the same strength as the base metal, more alloying elements should be added into the weld. Therefore, it is likely that the weld is expected to be more susceptible to cold cracking. The mechanism of strengthening and toughening of the weld should be carefully investigated. WISCO has made great progress in both property improvement and manufacturing of welding materials. Through the addition of alloying elements, the influences of some alloying elements on the strength and toughness of welds, especially on the low temperature toughness were carried out. The results show that the upper shelves of the Charpy V transition curves for the weld metals remain high despite the different alloying elements. However, the influence of alloying degree on the low-temperature toughness is significant. The weld metals micro-alloyed with Ti,B and Ni, etc. have high acicular ferrite volume fractions in the metallographs, thereby possessing high strengths and high toughness. For SAW weld, the strength is more than 590MPa, the Charpy impact energy at −40°C above 180J; for the weld of gas metal arc welding, the Charpy impact energy at −30°C reaches 190J which are far better than some current specifications. If the welding is performed with caution, no cracks were found. HIC and SSCC test for corrosion resistance of the welds were also performed and the results fully met the requirements concerned. With respect to strength and toughness, chemistry and metallography, the HIC performance of welds was analysed.
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Polishetty, Ashwin, Guy Littlefair, Thomas Musselwhite, and Chinmay Sonavane. "A Preliminary Study on Machinability Assessment of Nanobainite Steel." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64004.
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The demand for high strength materials and improvements in heat treatment techniques has given rise to this new form of high strength steel known as nanobainite steel. The production of nanobainite steel involves slow isothermal holding of austenitic steel around 200°C for 10 days, in order to obtain a carbon enriched austenite and cooling to room temperature using austempering. The microstructure of nanobainite steel is dual phase consisting of alternate layers of bainitic ferrite and austenite. The experimental design consists of face milling under 12 combination of Depth of Cut (DoC)-1, 2 and 3mm; cutting speed-100 and 150m/min; constant feed- 0.15mm/rev and coolant on/off. The machinability of the material is assessed by means of analysis such as metallography and cutting force analysis. The results obtained are used to assess the most favorable condition to machine this new variety of steel. Future work involves study on phase transformation by quantifying the microstructural phase before and after milling using XRD.
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Богданов, Роман Александрович. "IMPACT STRENGTH OF WAGON CASTINGS IN THE ASPECT OF THE INFLUENCE OF THE HARDNESS OF FERRITE AND PERLITE OF STEEL 20GL OPEN-HEARTH SMELTS." In Наука. Исследования. Практика: сборник избранных статей по материалам Международной научной конференции (Санкт-Петербург, Февраль 2021). Crossref, 2021. http://dx.doi.org/10.37539/srp295.2021.91.64.002.
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Методом оптической микроскопии провели металлографический анализ микроструктуры феррита (Фе) и перлита (II) различных образцов низколегированной стали 20ГЛ для вагонных отливок «Рама боковая» и «Балка надрессорная». Metallographic analysis of the microstructure of ferrite (Fe) and perlite (P) of various samples of low-alloy steel 20GL for the "Side frame" and "Spring beam" car castings was performed by optical microscopy.
Reports on the topic "Ferritic steel Metallography"
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Pressly, G. Quantitative metallographic method for determining delta ferrite content in austenitic stainless steels. Final report. Office of Scientific and Technical Information (OSTI), January 1986. http://dx.doi.org/10.2172/6239282.
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