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Littérature scientifique sur le sujet « Transformation de phase austénite-Ferrite »

Auteur : Grafiati

Publié le 1 février 2025

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Articles de revues sur le sujet "Transformation de phase austénite-Ferrite"

Kanter, Daniel, Yves Bolender, Christophe Rapin et Marie-Pierryle Filleul. « L’effet mémoire de forme est-il une réalité clinique pour le 35° Copper Ni-Ti® ? Étude par calorimétrie différentielle à balayage ». L'Orthodontie Française 84, n^o 3 (septembre 2013) : 259–69. http://dx.doi.org/10.1051/orthodfr/2013057.

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Introduction : Les alliages à base de nickel-titane-cuivre sont censés exprimer un effet mémoire de forme : refroidis en phase basse température puis soumis à une déformation apparemment plastique, ils devraient retrouver leur forme initiale par simple réchauffage en phase haute température. Les alliages à base de nickel-titane peuvent présenter différentes phases cristallographiques : martensite, austénite et une phase intermédiaire inconstante, la phase R. L’effet mémoire de forme est généralement associé à la transformation de martensite en austénite mais il peut aussi accompagner la transformation de phase R en austénite. Les températures buccales n’étant pas compatibles avec un alliage totalement martensitique, la présente étude vise, pour le 35° Copper Ni-Ti®, à rechercher la présence de phase R aux températures buccales et donc la possibilité d’exploiter l’effet mémoire de forme de la phase R en clinique. Matériels et méthodes : Trente fils 35° Copper Ni-Ti® provenant de deux lots distincts ont été consécutivement examinés par calorimétrie différentielle à balayage en cycles partiels, limités aux températures rencontrées dans la cavité buccale (de 0 °C à 50 °C). La présence d’une phase cristallographique intermédiaire a été recherchée sur les thermogrammes. Les températures de transformation ont été déterminées et les deux lots ont été comparés par le test U de Mann et Whitney. Résultats : Au chauffage, tous les fils sont passés directement de martensite en austénite. Af (moyenne = 33,5 °C, écart-type = 0,8 °C) était généralement inférieure à la température indiquée par le fabricant et une différence statistiquement significative (p ≤ 0,01) a été observée entre les deux lots. Conclusions : La présence de phase R n’a pas été détectée et les températures de transformation n’étaient pas constantes. Cette étude met en question la réalité clinique d’un effet mémoire de forme pour les fils 35° Copper Ni-Ti®.

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Padilha, Angelo Fernando, D. J. M. Aguiar et R. L. Plaut. « Duplex Stainless Steels : A Dozen of Significant Phase Transformations ». Defect and Diffusion Forum 322 (mars 2012) : 163–74. http://dx.doi.org/10.4028/www.scientific.net/ddf.322.163.

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During processing or use, duplex stainless steels are subject to a great number of significant phase transformations, such as solidification, partial ferrite transformation to austenite, ferrite eutectoid decomposition to sigma phase plus austenite, chi phase precipitation, chromium carbide precipitation, chromium nitride precipitation, ferrite spinodal decomposition, phase dissolution during solution annealing, forming of two types (epsilon and alpha prime) of strain induced martensite, martensite reversion to austenite, ferrite and austenite recrystallization. This paper summarizes the phase transformations that occur (individually or combined) in duplex stainless steels and presents some new results.

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Li, Li Zhang, He Wei, Lin Lin Liao, Yin Li Chen, Hai Feng Yan, Guang Hua Liu et Zhi Wei Sun. « Continuous Cooling Phase Transformation Rule of 20CrMnTi Low-Carbon Alloy Steel ». Materials Science Forum 944 (janvier 2019) : 303–12. http://dx.doi.org/10.4028/www.scientific.net/msf.944.303.

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Gear steel is a ferritic steel. In the rolling process, the ideal structure is ferrite + pearlite, and bainite or martensite is not expected. However, due to the high alloy content, the hardenability is good, and the bainite or martensite structure is very likely to be generated upon cooling after rolling. In this paper, phase transformation rules during continuous cooling of 20CrMnTi with and without deformation were studied to guide the avoidance of the appearance of bainite or martensite in steel. A combined method of dilatometry and metallography was adopted in the experiments, and the dilatometer DIL805A and thermo-simulation Gleeble3500 were used. Both dynamic and static continuous cooling transformation (CCT) diagrams were drawn by using the software Origin. The causes of those changes in starting temperature, finishing temperature, starting time and transformation duration in ferrite-pearlite phase transformation were analyzed, and the change in Vickers hardness of samples with different cooling rate was discussed. The results indicate that with different cooling rate, there are three phase transformation zones: ferrite-pearlite, bainite and martensite. Deformation of austenite accelerates the occurrence of transformation obviously and moves CCT curve to left and up direction. When the cooling rate is lower than 1 °C/s, the phases in samples are mainly ferrite and pearlite, which is the ideal microstructure of experimental steel. As the cooling rate increases, starting temperature of ferrite transformation in steel decreases, starting time reduces, transformation duration gradually decreases, and the Vickers hardness of samples increases. Under the cooling rate of 0.5 °C/s, ferrite transformation in deformed sample starts at 751.67 °C, ferrite-pearlite phase transformation lasts 167.9 s, and Vickers hardness of sample is 183.4 HV.

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Cheng, Wei Chun, Kun Hsien Lee, Shu Mao Lin et Shao Yu Chien. « The Observation of Austenite to Ferrite Martensitic Transformation in an Fe-Mn-Al Austenitic Steel after Cooling from High Temperature ». Materials Science Forum 879 (novembre 2016) : 335–38. http://dx.doi.org/10.4028/www.scientific.net/msf.879.335.

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Fe-Mn-Al steels with low density have the potential to substitute for TRIP (transformation induced plasticity) steels. For the development of Fe-Mn-Al TRIP steels, phase transformations play an important role. Our methods of studying the phase transformations of the Fe-16.7 Mn-3.4 Al (wt%) austenitic steel include heating and cooling. We have studied the martensitic transformation of the ternary Fe-Mn-Al steel. Single austenite phase is the equilibrium phase at 1373 K, and dual phases of ferrite and austenite are stable at low temperatures. It is noteworthy that lath martensite forms in the prior austenite grains after cooling from 1373 K via quenching, air-cooling, and/or furnace-cooling. The crystal structure of the martensite belongs to body-centered cubic. The formation mechanism of the ferritic martensite is different from the traditional martensite in steels. Ferrite is the stable phase at low temperature.

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Spiridonova, K. V., I. Yu Litovchenko, N. A. Polekhina, V. V. Linnik, T. A. Borisenko, V. M. Chernov et M. V. Leont’eva-Smirnova. « Structural-phase transformations of 12% chromium ferritic-martensitic steel EP-823 ». Izvestiya. Ferrous Metallurgy 66, n^o 6 (29 décembre 2023) : 725–32. http://dx.doi.org/10.17073/0368-0797-2023-6-725-732.

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The features of phase transformations of 12 % chromium ferritic-martensitic steel EP-823 under heating and cooling conditions in the temperature range from 30 to 1100 ℃ were studied by the methods of high-temperature X-ray diffraction analysis (XRD) in situ and differential scanning calorimetry (DSC). According to XRD in situ data, upon heating, the temperatures of the beginning and end of the (α → γ) transformation of ferrite (martensite – austenite) are Ac1 ≈ 880 °C, Ac3 ≈ 1000 °C, respectively. Upon cooling, a diffusion (γ → α) transformation occurs with critical points – Аr1 ≈ 860°С (beginning temperature) and Аr3 ≈ 840 °С (end temperature). According to DSC data, during heating, the critical points of the (α → γ) transformation are Ac1 ≈ 840 °C and Ac3 ≈ 900 °C. During cooling, a martensitic (γ → α) transformation is realized with critical points of the beginning of Ms = 344 ℃ and the end of Mf = 212 ℃ of this transformation. The XRD in situ analysis revealed no precipitation of carbide phases under heating and cooling conditions of steel EP-823. Position of the critical points of phase transformations depends on the research method (XRD in situ or DSC), which is determined by the difference in effective (taking into account the time for shooting in the XRD method) heating-cooling rate. The effect of elemental composition on the position of critical points of phase transformations and the formation of structural-phase states of ferritic-martensitic steels is discussed. It is shown that the increased content of ferrite-stabilizing elements (Cr, Mo, Nb) in composition of EP-823 steel, compared with other steels of the same class, expands the region of existence of the ferrite phase, which can contribute to an increase in the temperature of Ac1 .

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Xia, Pei Pei, Liu Qing Yang, Xiao Jiang Guo et Ye Zheng Li. « Continuous Cooling Phase Transformation Rules of High Nb X80 Pipeline Steel ». Materials Science Forum 850 (mars 2016) : 916–21. http://dx.doi.org/10.4028/www.scientific.net/msf.850.916.

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The microstructural evolution of the high Nb X80 pipeline steel in Continuous Cooling Transformation (CCT) by Gleeble-3500HS thermal mechanical simulation testing system was studied, the corresponding CCT curves were drawn and the influence of some parameters such as deformation and cooling rate on microstructure of high Nb X80 pipeline steel was analyzed. The results show that as cooling rate increased, the phase transformation temperature of high Nb X80 steel decreased, with the microstructure transformation from ferrite-pearlite to acicular ferrite and bainite-ferrite. When cooling rate was between 20°C/s and 30°C/s, the microstructure was comparatively ideal acicular ferrite, thermal deformation accelerates phase transformation notably and made the dynamic CCT curves move upward and the initial temperature of phase transformation increase obviously. Meanwhile the thermal deformation refined acicular ferrite and extended the range of cooling rate accessible to acicular ferrite.

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Wang, Qihui, Kun Chen, Kejia Liu, Lianbo Wang, Yu Chu et Bichen Xie. « Study on Characterization of Phase Transition in Continuous Cooling of Carbon Steel Using In Situ Thermovoltage Measurement ». Coatings 14, n^o 8 (3 août 2024) : 980. http://dx.doi.org/10.3390/coatings14080980.

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In this paper, a self-designed and enhanced thermovoltage measuring device was built to capture thermovoltage curves of 45 steel during continuous cooling. The phase zones of the thermovoltage curve were interpreted based on the Engel–Brewer electron theory and Fe-Fe3C phase diagram. The results show that the curve was stratified into three homogeneous phase zones and two-phase transition zones as follows: Zone Ι: single-phase austenite (A) zone; Zone III: austenite and ferrite (A+F) homogeneous phase zone; Zone V: ferrite and pearlite (P+F) homogeneous phase zone; Zone II: austenite to ferrite (A-F) phase transition zone; and Zone IV: austenite to pearlite (A-P) phase transition zone. Notably, the deflection point marked the transition temperature, which indicates that the thermovoltage curve can quantitatively characterize phase formation and transformation, as well as the phase transformation process. Furthermore, the sample was quenched at the measured ferrite phase transition temperature. Microstructure observations, electron probe microanalyzer (EPMA) and microhardness measurements corroborated our findings. Specifically, our experiments reveal ferrite precipitation first from the cold end at the phase transition temperature, leading to increased carbon content in adjacent austenite. The results of this study achieved the in situ characterization of bulk transformations during the materials heat treatment process, which expands the author’s research work conducted previously.

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Villalobos Vera, Doris Ivette, et Ivan Mendoza Bravo. « Effect of annealing temperature on the microstructure of hyperduplex stainless steels ». Ingeniería Investigación y Tecnología 20, n^o 2 (1 mars 2019) : 1–6. http://dx.doi.org/10.22201/fi.25940732e.2019.20n2.024.

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Samples of hyperduplex stainless steels were produced experimentally and exposed to different conventional annealing heat treatments in order to obtain the microstructural balance of 50% ferrite and 50% austenite. To differentiate the ferrite and austenite from any secondary phase, selective etching was used and quantitative metallography was performed to measure the percentage of phases. Results showed that conventional annealing heat treatments promote the transformation from ferrite to sigma phase and secondary austenite, suggesting a higher occurrence of sigma phase in the experimental hyperduplex alloys compared to other duplex alloys due to the superior content of chromium and molybdenum. On the other hand, a balanced microstructure free of secondary phases was accomplished increasing the temperature of the annealing heat treatment, which allowed the transformation of ferrite into austenite during cooling.

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Bilovol, V., et R. Martínez-García. « Phase transformation of strontium hexagonal ferrite ». Journal of Physics and Chemistry of Solids 86 (novembre 2015) : 131–37. http://dx.doi.org/10.1016/j.jpcs.2015.07.006.

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Hug-Amalric, Aurélie, Xavier Kleber, Jacques Merlin, Hélène Petitgand et Philip Meilland. « Characterization of Metallurgical Transformations in Multi-Phase High Strength Steels by Barkhausen Noise Measurement ». Materials Science Forum 539-543 (mars 2007) : 4283–88. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.4283.

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The potentialities of using the magnetic Barkhausen noise measurement in characterization of metallurgical transformations have been highlighted in multi-phase High Strength (HS) steels. This kind of steels are composed of different metallurgical constituents, such as ferrite, bainite, martensite or residual austenite. Recently, we found that it was possible to assess the proportion of phases in ferrite-martensite steels and in industrial Dual-Phase steels too. In this work, we show that the Barkhausen noise measurements can be also suitable to follow bainitic transformation in a TRIP steel.

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Thèses sur le sujet "Transformation de phase austénite-Ferrite"

Borges, Gomes Lima Yuri. « Μοdélisatiοn atοmistique de la transfοrmatiοn de phase austénite-ferrite dans les aciers ». Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMR086.

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Cette thèse applique l'approche des Quasiparticles (QA) pour étudier les mécanismes à l'échelle atomique qui conduisent à la transformation de phase CFC à CC dans le fer. Dans un premier temps, cette étude se concentre sur le fer pur, fournissant des résulats détaillés sur la nature et le rôle des dislocations à l'interface CFC-CC. Il a été montré que l'interface CFC-CC est semi-cohérente, avec des marches, et contient deux réseaux de dislocations de transformations. L'approche des Quasiparticles a permis de révéler l'influence de la relation d'orientation sur les caractéristiques de l'interface. Bien que les relations d'orientation étudiées ont montré diférentes structures d'interface, il a été démontré que toutes suivent le même chemin de transformation atomique, dû au glissement des dislocations de transformation à l'interface. Il a été conclu que la transformation complète de CFC à CC implique le mécanisme de transformation de Kurdjumov-Sachs (KS) en deux variantes le long des lignes de dislocations, avec le mécanisme de transformation de Kurdjumov-Sachs-Nishiyama (KSN) qui émerge comme la moyenne de l'action des deux mécanismes KS. Cette description détaillée a servi de base pour l'étude des systèmes Fe-C, où la ségrégation du carbone à l'interface a été observée. De plus, il a été montré que les profils de concentration de carbone sont cohérents avec des conditions d'équilibre local à l'interface
This thesis applies the Quasiparticle Approach (QA) to investigate the atomic scale mechanisms driving the phase transformation from FCC to BCC structures in iron. Initially, the study focuses on pure iron, providing detailed results into the nature and role of dislocations, at the FCC-BCC interface. It was shown that the FCC-BCC interface is semi-coherent and stepped, with two sets of transformations dislocations at the interface. The QA framework reveals how each orientation relationship (OR) influences the interface characteristics. Although the ORs displayed different interface structures, all were ultimately found to follow the same atomic transformation path, driven by the glide of transformation dislocations at the interface. It was concluded that the complete FCC to BCC phase transformation involves the action of the Kurdjumov-Sachs (KS) transformation mechanism in two variants along the two sets of dislocations, with the Kurdjumov-Sachs-Nishiyama (KSN) mechanism emerging as the average of the two KS mechanisms. This detailed description served as a basis for the study of Fe-C systems, where carbon segregation at the interface was observed. Moreover, it was shown that the carbon concentration profiles were consistent with local equilibrium conditions at the interface

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Perevoshchikova, Nataliya. « Modeling of austenite to ferrite transformation in steels ». Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0342/document.

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La thèse porte sur la modélisation de la transformation de l'austénite en ferrite dans les aciers en mettant l'accent sur les conditions thermodynamiques et cinétiques aux interfaces alpha/gamma en cours de croissance de la ferrite. Dans une première partie, la thèse se concentre sur la description des équilibres thermodynamiques entre alpha et gamma à l'aide de la méthode CalPhad. Nous avons développé un nouvel algorithme hybride combinant la construction d'une enveloppe convexe avec la méthode classique de Newton-Raphson. Nous montrons ses possibilités pour des aciers ternaire Fe-C-Cr et quaternaire Fe-C-Cr-Mo dans des cas particulièrement difficiles. Dans un second chapitre, un modèle à interface épaisse a été développé. Il permet de prédire l'ensemble du spectre des conditions à l'interface alpha/gamma au cours de la croissance de la ferrite, de l'équilibre complet au paraéquilibre avec des cas intermédiaires des plus intéressants. Nous montrons que de nombreux régimes cinétiques particuliers dans les systèmes Fe-C-X peuvent être prévus avec un minimum de paramètres d'ajustement, principalement le rapport entre les diffusivités de l'élément substitutionnel dans l'interface épaisse et dans le volume d'austénite. Le troisième chapitre porte sur l'étude d'un modèle de champ de phase. Une analyse approfondie des conditions à l'interface données par le modèle est réalisée en utilisant la technique des développements asymptotiques. En utilisant les connaissances fournies par cette analyse, le rôle de la mobilité intrinsèque d'interface sur la cinétique et les régimes de croissance est étudié, à la fois dans le cas simple d'alliages binaires Fe-C et dans le cas plus complexe d'alliages Fe-C-Mn
Transformation in steels focusing on the thermodynamic and kinetics conditions at the alpha/gamma interfaces during the ferrite growth. The first chapter deals with the determination of thermodynamic equilibria between alpha and gamma with CalPhad thermodynamic description. We have developed a new hybrid algorithm combining the construction of a convex hull to the more classical Newton-Raphson method to compute two phase equilibria in multicomponent alloys with two sublattices. Its capabilities are demonstrated on ternary Fe-C-Cr and quaternary Fe-C-Cr-Mo steels. In the second chapter, we present a thick interface model aiming to predict the whole spectrum of conditions at an alpha/gamma interface during ferrite growth, from full equilibrium to paraequilibrium with intermediate cases as the most interesting feature. The model, despite its numerous simplifying assumptions to facilitate its numerical implementation, allows to predict some peculiar kinetics in Fe-C-X systems with a minimum of fitting parameters, mainly the ratio between the diffusivities of the substitutional element inside the thick interface and in bulk austenite. The third chapter deals with the phase field model of austenite to ferrite transformation in steels. A thorough analysis on the conditions at the interface has been performed using the technique of matched asymptotic expansions. Special attention is given to clarify the role of the interface mobility on the growth regimes both in simple Fe-C alloys and in more complex Fe-C-Mn alloys

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Thuillier, Olivier. « Transformation austénite-ferrite dans un alliage modèle Fe-C-Mn : modélisation et étude expérimentale à l'échelle nanométrique ». Rouen, 2007. http://www.theses.fr/2007ROUES082.

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Le travail présenté dans ce manuscrit a pour objectif d'étudier les conditions d'équilibre chimique local près d'une interface en mouvement lors de la transformation austénite ferrite dans un alliage ternaire Fe-C-Mn en cours de transformation. Nous avons modélisé thermocinétiquement le système, pour prédire les taux de ferrite formée en fonction du mode de transformation. Ces résultats ont été comparés à des résultats expérimentaux obtenus par tomographie atomique. Aucun des modes classiques ne permettant de décrire les résultats expérimentaux, nous nous sommes intéressés à un mode hybride, dit CRH, qui décrit mieux la cinétique observée. Nous avons ensuite raffiné ce modèle. Les résultats obtenus montrent un excellent accord avec les résultats expérimentaux. La comparaison des profils de concentration obtenus par tomographie atomique avec ceux du modèle montre encore une fois un accord quasi-parfait, validant ainsi les hypothèses utilisées pour la modélisation.

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Liebaut, Christophe. « Rhéologie de la déformation plastique d'un acier Fe-C durant sa transformation de phase "austenite-->ferrite + perlite" ». Vandoeuvre-les-Nancy, INPL, 1988. http://www.theses.fr/1988NAN10451.

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Schmidt, Marek Wojciech, et Marek Schmidt@rl ac uk. « Phase formation and structural transformation of strontium ferrite SrFeOx ». The Australian National University. Research School of Physical Sciences and Engineering, 2001. http://thesis.anu.edu.au./public/adt-ANU20020708.190055.

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Non-stoichiometric strontium iron oxide is described by an abbreviated formula SrFeOx (2.5 ≤ x ≤ 3.0) exhibits a variety of interesting physical and chemical properties over a broad range of temperatures and in different gaseous environments. The oxide contains a mixture of iron in the trivalent and the rare tetravalent state. The material at elevated temperature is a mixed oxygen conductor and it, or its derivatives,can have practical applications in oxygen conducting devices such as pressure driven oxygen generators, partial oxidation reactors in electrodes for solid oxide fuel cells (SOFC). ¶ This thesis examines the behaviour of the material at ambient and elevated temperatures using a broad spectrum of solid state experimental techniques such as: x-ray and neutron powder diffraction,thermogravimetric and calorimetric methods,scanning electron microscopy and Mossbauer spectroscopy. Changes in the oxide were induced using conventional thermal treatment in various atmospheres as well as mechanical energy (ball milling). The first experimental chapter examines the formation of the ferrite from a mixture of reactants.It describes the chemical reactions and phase transitions that lead to the formation of the oxide. Ball milling of the reactants prior to annealing was found to eliminate transient phases from the reaction route and to increase the kinetics of the reaction at lower temperatures. Examination of the thermodynamics of iron oxide (hematite) used for the reactions led to a new route of synthesis of the ferrite frommagnetite and strontium carbonate.This chapter also explores the possibility of synthesis of the material at room temperature using ball milling. ¶ The ferrite strongly interacts with the gas phase so its behaviour was studied under different pressures of oxygen and in carbon dioxide.The changes in ferrite composition have an equilibrium character and depend on temperature and oxygen concentration in the atmosphere. Variations of the oxygen content x were described as a function of temperature and oxygen partial pressure, the results were used to plot an equilibrium composition diagram. The heat of oxidation was also measured as a function of temperature and oxygen partial pressure. ¶ Interaction of the ferrite with carbon dioxide below a critical temperature causes decomposition of the material to strontium carbonate and SrFe12O19 . The critical temperature depends on the partial pressure of CO2 and above the critical temperature the carbonate and SrFe12O19 are converted back into the ferrite.The resulting SrFe12O19 is very resistant towards carbonation and the thermal carbonation reaction does not lead to a complete decomposition of SrFeOx to hematite and strontium carbonate. ¶ The thermally induced oxidation and carbonation reactions cease at room temperature due to sluggish kinetics however,they can be carried out at ambient temperature using ball milling.The reaction routes for these processes are different from the thermal routes.The mechanical oxidation induces two or more concurrent reactions which lead to samples containing two or more phases. The mechanical carbonation on the other hand produces an unknown metastable iron carbonate and leads a complete decomposition of the ferrite to strontiumcarbonate and hematite. ¶ Thermally and mechanically oxidized samples were studied using Mossbauer spectroscopy. The author proposes a new interpretation of the Sr4Fe4O11 (x=2.75) and Sr8Fe8O23 (x=2.875)spectra.The interpretation is based on the chemistry of the compounds and provides a simpler explanation of the observed absorption lines.The Mossbauer results froma range of compositions revealed the roomtemperature phase behaviour of the ferrite also examined using x-ray diffraction. ¶ The high-temperature crystal structure of the ferrite was examined using neutron powder diffraction.The measurements were done at temperatures up to 1273K in argon and air atmospheres.The former atmosphere protects Sr2Fe2O5 (x=2.5) against oxidation and the measurements in air allowed variation of the composition of the oxide in the range 2.56 ≤ x ≤ 2.81. Sr2Fe2O5 is an antiferromagnet and undergoes phase transitions to the paramagnetic state at 692K and from the orthorhombic to the cubic structure around 1140K.The oxidized formof the ferrite also undergoes a transition to the high-temperature cubic form.The author proposes a new structural model for the cubic phase based on a unit cell with the Fm3c symmetry. The new model allows a description of the high-temperature cubic form of the ferrite as a solid solution of the composition end members.The results were used to draw a phase diagramfor the SrFeOx system. ¶ The last chapter summarizes the findings and suggests directions for further research.

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Pariser, Gerhard Carolus. « Modeling the austenite to ferrite phase transformation for steel development / ». Aachen : Shaker, 2006. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014913109&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.

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Guiheux, Romain. « Comportement d’aciers à transformation de phase austénite-martensite pour la simulation du grenaillage de précontrainte ». Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0055/document.

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Le grenaillage de précontrainte est un procédé couramment utilisé dans l’industrie (automobile, aréonautique, …) pour augmenter la durée de vie des pièces mécaniques et de structure : des contraintes de compression sont générées par déformation plastique de la surface. Dans le cas des aciers TRIP (TRansformation Induced Plasticity), qui possèdent une microstructure complexe, l’austénite métastable est susceptible de se transformer en martensite lors du grenaillage. L’état de contraintes obtenu est donc complexe : il résulte de l’effet combiné de la déformation plastique induite par le procédé et de la transformation martensitique qui conduit à une redistribution des contraintes entre l’austénite et la martensite. Ce travail a pour objectif de caractériser expérimentalement l’état mécanique, à l’échelle des phases, de différents aciers TRIP (AISI 301LN, TRIP 780 et 23MnCrMo5) ainsi que leurs fractions de phase respectives après grenaillage et d’en proposer une modélisation par éléments finis pouvant être, à terme, utilisée en bureaux d’études. Le modèle élastoplastique à transformation de phase, développé dans cette thèse, permet de prédire l’évolution des différents champs mécaniques, de manière macroscopique mais également à l’échelle des phases, ainsi que l’évolution de la fraction d’austénite résiduelle
Shot-peening is commonly used in mechanical industries to increase life duration of mechanical and structural parts: residual compressive stresses are developed at the sub-surface of the material by plastic stretching of the surface. In the case of TRIP-effect steels (TRansformation Induced Plasticity), the metastable austenite can transform into martensite during shot-peening. The final distribution of stress is then more complex than for “standard steels” as it results from the mechanical strain imposed by the process and the martensitic transformation leading to a stress redistribution between austenite, martensite and the other phases. This work aims to characterize experimentally the mechanical state, at phase scale, of different TRIP steels (AISI 301LN, TRIP 780 and 23MnCrMo5) as well as the fraction of each phase after shot-peening and to propose a numerical model by finite elements which could be used in the future by engineering offices. An elastoplastic model with phase transformation was developed in this thesis which permits to predict the evolution of mechanical variables, macroscopically and at the phase scale, as well as the evolution of austenite volume fraction

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Pariser, Gerhard C. [Verfasser]. « Modeling the Austenite to Ferrite Phase Transformation for Steel Development / Gerhard C Pariser ». Aachen : Shaker, 2006. http://d-nb.info/1170529216/34.

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Rampelberg, Cécile. « Characterization and modeling of Carbide-Free Bainite transformations along isothermal and anisothermal heat treatments ». Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0202.

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Les bainites sans carbure sont des microstructures multiphasées obtenues par décomposition de l'austénite à basse température (généralement entre 450 °C et 200 °C) dans les aciers alliés. Ces microstructures sont très intéressantes en raison de leurs propriétés mécaniques élevées et de leur bonne ténacité, notamment pour les pièces forgées destinées au marché automobile. Grâce à un choix judicieux de leur composition chimique, elles sont constituées d'une fine matrice ferritique sans carbure, d'austénite résiduelle stabilisée par enrichissement en carbone lors de la transformation et de martensite. L'austénite résiduelle peut se transformer en martensite lors de sollicitations mécaniques ultérieures à température ambiante (strain induced transformation). Une des grandes nouveautés de ce travail a été de comprendre les mécanismes de formation de ces microstructures en conditions de refroidissement continu. Ces microstructures ont été étudiées depuis de nombreuses années, mais leurs mécanismes de formation restent un sujet qui continue de diviser la communauté métallurgique, entre approches « diffusive » et « diffusionless ». Le phénomène de transformation incomplète rencontré dans ce processus est l'un des points de discorde.Dans ce travail, nous avons étudié l'évolution des microstructures au cours de différents traitements thermiques (maintiens isothermes, traitements étagés et traitements de refroidissement continu) par Diffraction des Rayons X à Haute Energie (DRXHE) in situ sur ligne de lumière synchrotron. Ces expériences permettent la mesure simultanée de la cinétique de transformation de phase, des paramètres de maille des différentes phases et la détection d'éventuels processus de précipitation des carbures. Sur cette base, des bilans massiques de carbone très précis entre les phases constituant la microstructure ont été établis pour la première fois, ce qui a permis de conclure que la bainite ferritique est encore plus sursaturée en carbone que prévu. Les expériences par traitements étagés et de refroidissement continu ont également prouvé que la transformation bainitique ne respecte pas la règle d'additivité des transformations purement diffusives et est très sensible aux séquences de transformation. Les microstructures après traitements thermiques ont été systématiquement étudiées post mortem par microscopie électronique à balayage (MEB) couplée à la diffraction des électrons rétrodiffusés (EBSD). Cela a permis d'expliquer les microstructures observées après un refroidissement continu, qui présentent des distributions étendues de taille, de morphologie et de microtexture du fait de leur formation à différentes températures.Un modèle de transformation de phase basé sur l'approche sans diffusion de Van Bohemen (2019) a finalement été développé et calibré sur les données expérimentales disponibles. Ce modèle est non seulement capable de simuler la cinétique de la transformation bainitique le long d'un maintien isotherme et de refroidissements continus, mais aussi les compositions respectives des phases. Les capacités et les limites de la nouvelle approche sont analysées et discutées
Carbide-Free Bainites are multiphase microstructures obtained from austenite decomposition at low temperatures (typically between 450 °C and 200 °C) in alloyed steels. These microstructures are very attractive owing to their high mechanical properties and good toughness especially for forged parts dedicated to the automotive market. They are made of a fine ferritic matrix without carbide thanks to a judicious chemical composition, retained austenite stabilized by carbon partitioning during the transformation and martensite. The high fraction of retained austenite may transform in martensite during further mechanical solicitations at room temperature (strain induced transformation). These microstructures have been studied since many years, but their formation mechanisms are still a subject that continues to divide the metallurgy community, between diffuse and diffusionless approaches. The incomplete transformation phenomenon encountered in this process is one of the bones of contention. One of the great novelties of this work was to elucidate the mechanisms of formation of these microstructures in continuous cooling conditions.In this work, we have investigated the evolution of microstructures along different thermal treatments (isothermal holdings, multistep and continuous cooling treatments) by in situ High Energy X-Ray Diffraction (HEXRD) on synchrotron beamlines. Such experiments make possible the simultaneous measurement of phase transformation kinetics, of the lattice parameters of the different phases and the detection of possible carbide precipitation processes. On this basis, very precise carbon mass balances between the constituting phases have been established for the first time leading to the conclusions that the ferritic bainite is even more supersaturated in carbon that expected. The multistep and continuous cooling experiments have also proved that the bainitic transformation doesn’t respect the additivity rule of purely diffusive transformations and is highly sensitive to the transformation sequences. The microstructures after thermal treatments have been systematically studied post mortem by Scanning Electron microscopy (SEM) coupled with Electron Back Scattered Diffraction (EBSD). It has served to explain the observed microstructures after continuous cooling which show large distributions of size, morphology and microtexture as they are formed progressively at different temperatures.A phase transformation model based on the diffusionless-type approach of Van Bohemen (2019) was finally developed and calibrated on available experimental data. This model is not only able to simulate bainite kinetics along isothermal holding and continuous cooling but also the respective compositions of the phases. The capabilities and limits of the new approach are analyzed and discussed

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Liebaut, Christophe. « Rhéologie de la déformation plastique d'un acier Fe-C durant sa transformation de phase "austénite-ferrite + perlite" ». Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376152470.

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Chapitres de livres sur le sujet "Transformation de phase austénite-Ferrite"

An, Dong, Shiyan Pan, Qing Yu, Chen Lin, Ting Dai, Bruce Krakauer et Mingfang Zhu. « Modeling of Ferrite-Austenite Phase Transformation ». Dans TMS2015 Supplemental Proceedings, 791–98. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2015. http://dx.doi.org/10.1002/9781119093466.ch96.

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An, Dong, Shiyan Pan, Qing Yu, Chen Lin, Ting Dai, Bruce Krakauer et Mingfang Zhu. « Modeling of Ferrite-Austenite Phase Transformation ». Dans TMS 2015 144th Annual Meeting & ; Exhibition, 791–98. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-48127-2_96.

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López-Baltazar, Alejandro, Armando Salinas-Rodríguez et Enrique Nava-Vázquez. « Austenite-Ferrite Transformation in Hot Rolled Mn-Cr-Mo Dual Phase Steels ». Dans Advanced Structural Materials III, 79–84. Stafa : Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-446-4.79.

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Gamsjäger, Ernst. « Kinetics of the Austenite-to-Ferrite Phase Transformation - From the Intrinsic to an Effective Interface Mobility ». Dans THERMEC 2006, 2570–75. Stafa : Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-428-6.2570.

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Neidel, A., B. Fischer, S. Riesenbeck, E. Cagliyan et E. Engert. « Transformation of Delta Ferrite Into Sigma Phase in Metastable Austenitic Stainless Steels After Long-Term High-Temperature Service Exposure ». Dans Schadensfallanalysen metallischer Bauteile, 267–89. München, Germany : Carl Hanser Verlag GmbH & Co. KG, 2015. http://dx.doi.org/10.1007/978-3-446-44609-0_21.

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Neidel, A., B. Fischer, S. Riesenbeck, E. Cagliyan et E. Engert. « Transformation of Delta Ferrite Into Sigma Phase in Metastable Austenitic Stainless Steels After Long-Term High-Temperature Service ExposureUmwandlung von Deltaferrit in Sigma-Phase in metastabilen rostfreien austenitischen Stählen nach Langzeitbeanspruchung durch Hochtemperaturen ». Dans Schadensfallanalysen metallischer Bauteile, 267–89. München : Carl Hanser Verlag GmbH & Co. KG, 2015. http://dx.doi.org/10.3139/9783446446090.021.

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Jaber, Hassanen, et Tunde Kovacs. « Dissimilar Resistance Spot Welding of Ferrite-Martensite Dual Phase Steel/Low Carbon Steel : Phase Transformations and Mechanical Properties ». Dans Lecture Notes in Mechanical Engineering, 709–18. Cham : Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-75677-6_60.

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Choi, Sangwoo, Il-Heon Son, Joong-Ki Hwang, Young Soo Chun, Nam-Suk Lim Lim, Hyun-Ho Kim et Jang-Yong Yoo. « A New Method to Compute the Behavior of Phase Transformations and Depth of the Decarburized Ferrite Layer, Scale Thickness of Steel from Measured Temperatures ». Dans HSLA Steels 2015, Microalloying 2015 & ; Offshore Engineering Steels 2015, 427–32. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2015. http://dx.doi.org/10.1002/9781119223399.ch49.

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Choi, Sangwoo, Il-Heon Son, Joong-Ki Hwang, Young Soo Chun, Nam-Suk Lim, Hyun-Ho Kim et Jang-Yong Yoo. « A New Method to Compute the Behavior of Phase Transformations and Depth of the Decarburized Ferrite Layer, Scale Thickness of Steel from Measured Temperatures ». Dans HSLA Steels 2015, Microalloying 2015 & ; Offshore Engineering Steels 2015, 427–32. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48767-0_49.

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RÉGLÉ, Hélène, et Brigitte BACROIX. « Anisotropie et propriétés mécaniques ». Dans Le développement des aciers à très haute résistance, 53–78. ISTE Group, 2022. http://dx.doi.org/10.51926/iste.9122.ch2.

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Ce chapitre traite de l’influence du développement de textures cristallographiques sur l’anisotropie. Un rappel est fait des composantes de texture dans les phases ferrite et austénite, présentes dans les nouveaux aciers. Les textures héritées lors de la transformation de phase sont décrites. L’impact des textures est modélisé sur l’anisotropie du module d’Young, du coefficient de Langford et de la surface de plasticité.

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Actes de conférences sur le sujet "Transformation de phase austénite-Ferrite"

Hatakeyama, Tomotaka, Kota Sawada, Masaru Suzuki et Makoto Watanabe. « Microstructure of Modified 9Cr-1Mo Steel Manufactured via Laser Powder Bed Fusion ». Dans AM-EPRI 2024, 365–72. ASM International, 2024. http://dx.doi.org/10.31399/asm.cp.am-epri-2024p0365.

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Abstract Modified 9Cr-1Mo steel was manufactured via laser powder bed fusion (LPBF) using gas atomized powders under various building conditions. Dense samples were obtained at an energy density of 111-125 J/mm3. As-built samples were subjected to a normalization and tempering heat treatments. The microstructure of the as-built sample exhibits a duplex structure, comprising coarse columnar δ-ferrite grains and fine martensite grains. In addition, a small amount of retained austenite phase was observed at the interface between δ-ferrite and martensite. The formation of δ-ferrite is attributed to the extremely rapid solidification that occurs during the LPBF process, while martensite is obtained through the phase transformation because of the thermal cycles experienced during the process. The area fraction of δ-ferrite and martensite can be controlled by adjusting the LPBF parameters. Typical as-built microstructure morphology characterized by the columnar δ- ferrite was eliminated after the heat treatments, resulting in a tempered martensitic microstructure that is identical with that obtained through the conventional process. However, an increase in prior austenite grain size was observed when the area fraction of δ-ferrite in the as-built condition was high, due to faster phase transformation kinetics of martensite than that of δ-ferrite during the normalization. This suggests that the prior austenite grain size can be controlled by optimizing the area fraction of δ-ferrite and martensite in the as-built microstructure.

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Li, Zhichao (Charlie), B. Lynn Ferguson, Edward Lee, Stefan Habean et Jason Meyer. « Sources of Heat Treatment Distortion and Approaches for Distortion Reduction during Quench Hardening Process ». Dans IFHTSE 2024, 132–38. ASM International, 2024. http://dx.doi.org/10.31399/asm.cp.ifhtse2024p0132.

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Abstract Heat treatment of steels is a process of modifying the mechanical properties by solid-state phase transformations or microstructural changes through heating and cooling. The material volume changes with phase transformations, which is one of the main sources of distortion. The thermal stress also contributes to the distortion, and its effect increases with solidstate phase transformations, as the material stays in the plastic deformation field due to the TRIP effect. With the basic understanding described above, the sources of distortion from a quench hardening process can be categorized as: 1) nonuniform austenitizing transformation during heating, 2) nonuniform austenite decomposing transformations to ferrite, pearlite, bainite or martensite during quenching, 3) adding of carbon or nitrogen to the material, and forming carbides or nitrides during carburizing or nitriding, 4) coarsening of carbide in tempered martensite during tempering, 5) stress relaxation from the initial state, 6) thermal stress caused by temperature gradient, and 7) nonhomogeneous material conditions, etc. With the help of computer modeling, the causes of distortion by these sources are analyzed and quantified independently. In this article, a series of modeling case studies are used to simulate the specific heat treatment process steps. Solutions for controlling and reducing distortion are proposed and validated from the modeling aspect. A thinwalled part with various wall section thickness is used to demonstrate the effectiveness of stepped heating on distortion caused by austenitizing. A patented gas quenching process is used to demonstrate the controlling of distortion with martensitic transformation for high temperature tempering steels. The effect of adding carbon to austenite on size change during carburizing is quantified by modeling, and the distortion can be compensated by adjusting the heat treat part size.

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P., Sumangala T., Mahender C., Venkataramani N. et Shiva Prasad. « Temperature dependent phase transformation in nano sized magnesium ferrite ». Dans NANOFORUM 2014. AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4917771.

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Mochizuki, Masahito, et Yoshiki Mikami. « Heterogeneous Microstructure Effect on Residual Stress and Fatigue Crack Resistance in Dual-Phase Materials ». Dans ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77446.

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The effect of transformation-induced microscopic residual stress on fatigue crack propagation behaviour of ferrite-martensite lamellar steel was discussed. Fatigue tests of prestrained and non-prestrained specimens were performed. Inflections and branches at ferrite-martensite boundaries were observed in the non-prestrained specimens. On the other hand, less inflections and branches were found in the prestrained specimens. The experimental results showed that the transformation induced microscopic residual stress has influence on the fatigue crack propagation behaviour. To estimate the microscopic residual stress distribution, a numerical simulation of microscopic residual stress induced by martensitic transformation was performed. The simulation showed that compressive residual stress was generated in martensite layer, and the result agree with the experimental result that inflections and branches were observed at ferrite-martensite boundaries. In addition, the change in the microscopic residual stress distribution by prestraining was also calculated to show the compressive residual stress changed to tensile by prestraining. This also agree with the experimental result of the observation of fatigue crack path.

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Stritch, Kyle, et Boian T. Alexandrov. « Microstructural Evolution and Mechanical Properties in Simulated Heat Affected Zone Regions of Grade 91 Welds ». Dans AM-EPRI 2016, sous la direction de J. Parker, J. Shingledecker et J. Siefert. ASM International, 2016. http://dx.doi.org/10.31399/asm.cp.am-epri-2016p1160.

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Abstract Grade 91 steel has been found to be susceptible to Type IV cracking in the base metal heat affected zone (HAZ). In order to better understand this type of failure, a study on the metallurgical reactions occuring within the HAZ was conducted, particularly within the fine grained (FG) and intercritical (IC) regions where Type IV cracking is most commonly found to occur. The course grained (CG), FG and IC regions of the HAZ in Grade 91 steel were simulated using a Gleeble 3800 Thermo-Mechanical Simulator. A dilatometer was used to determine the phase transformations occuring during simulation of weld thermal histories. For the first time, it was shown that ferrite can form in the IC HAZ of Grade 91 steel welds. The magnitude of the ferrite transformation was observed to decrease with faster cooling rates. The presence of ferrite in the simulated IC HAZ microstructure was shown to decrease the high temperature tensile strength and increase the high temperature elongation compared to HAZ regions that did not undergo ferrite transformation. Welding parameters such as heat input, preheat and interpass temperature can be selected to ensure faster cooling rates and reduce or potentially avoid formation of ferrite in the IC HAZ.

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Cabo Rios, Alberto, Eduard Hryha, Eugene Olevsky et Mats Persson. « Modelling Of Delta-ferrite Transformation Effect On The Sintering Behavior Of 316L Binder Jetting Components ». Dans World Powder Metallurgy 2022 Congress & Exhibition. EPMA, 2022. http://dx.doi.org/10.59499/wp225371818.

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The main objective of this study is to develop a simulation methodology that accounts for phase transformation (δ-ferrite) during the sintering of 316L stainless steel binder jetted (BJ) components. The model was based on the continuum theory of sintering develop by Skorohod and Olevsky. Dilatometry sintering tests at different heating rates up to 1370°C were performed. The constitutive parameters for the sintering model were obtained by dilatometry data analysis. Dilatometry results at different heating rates showed minor influence of the δ-ferrite transformation kinetics on the material viscosity. Thus, a new temperature-dependent material viscosity function was proposed to include the δ-ferrite transformation. The new model proposed was used to predict the densification behaviour of 316L BJ samples subjected to dilatometry experiments at different temperatures and times. The influence of δ-ferrite on the densification was accurately predicted for the material and sintering conditions studied.

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Toloui, Morteza, et Matthias Militzer. « Phase Field Modelling of Microstructure Evolution in the HAZ of X80 Linepipe Steel ». Dans 2012 9th International Pipeline Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ipc2012-90378.

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The heat affected zone (HAZ) during welding experiences a very steep temperature gradient which results in significant microstructure gradients. Thus, model approaches on the length scale of the microstructure, i.e. the so-called mesoscale, are useful to accurately simulate microstructure evolution in the HAZ. In this study, a phase field model (PFM) is employed to simulate austenite grain growth and austenite decomposition in the HAZ of an X80 linepipe steel microalloyed with Nb and Ti. The interfacial mobilities and nucleation conditions are obtained by benchmarking the PFM with experimental data from austenite grain growth and continuous cooling transformation tests. An effective grain boundary mobility is introduced for austenite grain growth to implicitly account for dissolution of NbC. Subsequently, austenite decomposition into polygonal ferrite and bainite is considered. For this purpose the PFM is coupled with a carbon diffusion model. Ferrite nuclei are introduced at austenite grain boundaries and suitable interfacial mobilities are selected to reproduce experimental ferrite formation kinetics. Bainite nucleation occurs for a sufficiently high undercooling at available interface sites (i.e. austenite grain boundaries and/or austenite-ferrite interfaces). For simplicity, the formation of carbide-free bainite is considered and a suitable anisotropy approach is proposed for the austenite-bainite interface mobility. The model is then used to predict austenite grain growth and phase transformation in the HAZ.

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Yuan, Zhetao, Satoru Kobayashi et Masao Takeyama. « Microstructure Control Using the Formation of Laves Phase through Interphase Precipitation in Ferritic Heat Resistant Steels ». Dans AM-EPRI 2019, sous la direction de J. Shingledecker et M. Takeyama. ASM International, 2019. http://dx.doi.org/10.31399/asm.cp.am-epri-2019p0090.

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Abstract The formation of periodically arrayed rows of very fine Fe2Hf Laves phase particles was recently found in 9 wt. % chromium ferritic matrix through interphase precipitation along a reaction path of δ-ferrite → γ-austenite + Fe2Hf with a subsequent phase transformation of the γ phase into the α-ferrite phase. One of the problems on the formation of the fine Laves phase dispersion is a poor heat treatability; the interphase precipitation (δ-Fe→γ-Fe+Fe2Hf) is competitive with the precipitation of Laves phase from the δ phase in the eutectoid-type reaction pathway (δ→δ+Fe2Hf). In the present work, the effect of supersaturation on the precipitation of Laves phase from δ phase (δ→δ+Fe2Hf) and the δ→γ transformation in the reaction pathway was investigated by changing the Hf and Cr contents. The results obtained suggest that it is effective to have a high supersaturation for the precipitation of Laves phase and an adequately high supersaturation for the δ→γ transformation at the same time in order to widen the window of the interphase precipitation

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Liu, Dehao, Gang Wang, Zhenguo Nie et Yiming (Kevin) Rong. « Numerical Simulation of the Austenitizing Process in Hypoeutectoid Fe-C Steels ». Dans ASME 2014 International Manufacturing Science and Engineering Conference collocated with the JSME 2014 International Conference on Materials and Processing and the 42nd North American Manufacturing Research Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/msec2014-3948.

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For predicting of diffusive phase transformations during the austenitizing process in hypoeutectoid Fe-C steels, a two-dimensional model has been developed. The diffusion equations are solved within each phase (α and γ) using an explicit finite volume technique formulated using a square grid. The discrete α/γ interface is represented by special volume elements α/γ. The result showing the dissolution of ferrite particles in the austenite matrix are presented at different stages of the phase transformation. Specifically, the influence of the microstructure scale and heating rate on the transformation kinetics has been investigated. Final austenitization temperature calculated with this 2D model is compared with predictions of a simpler one dimensional (1D) front-tracking calculation.

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Silva, Edgard, ANA SILVA SOUZA ANDRADE, Francildo de Oliveira, Michelline Nery Azevedo Lima, Josinaldo Leite, João Leite et Mickael Messias Rodrigues da Silva. « Detection of ferrite phase transformation by induced magnetic field on a duplex stainless steel ». Dans 24th ABCM International Congress of Mechanical Engineering. ABCM, 2017. http://dx.doi.org/10.26678/abcm.cobem2017.cob17-1035.

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