Prediction of martensitic transformation and deformation behavior in the TRIP steel sheet forming

Shan, Tikun; Li, S.H.; Zhang, W.G.; Xu, Zhenming

doi:10.1016/j.matdes.2008.03.023

Cited by 63 publications

(18 citation statements)

References 19 publications

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“…As the orientation of ferrite grains is different from that of its neighboring grains, each of these grains tends to deform differently resulting in higher stresses at the grain boundaries. In the general case, this will result in a triaxial state of stress on the grains of austenite and these are apparently more likely to transform during the deformation as suggested by Shan et al [19]. In principle, apart from triple junctions, austenite grains can also be present at quadruple junctions within these steels.…”

Section: Austenite Grains At Ferrite Triple Junctionsmentioning

confidence: 87%

Deformation-induced austenite grain rotation and transformation in TRIP-assisted steel

et al. 2012

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Uniaxial straining experiments were performed on a rolled and annealed Si-alloyed TRIP (transformation-induced plasticity) steel sheet in order to assess the role of its microstructure on the mechanical stability of austenite grains with respect to martensitic transformation. The transformation behavior of individual metastable austenite grains was studied both at the surface and inside the bulk of the material using electron back-scattered diffraction (EBSD) and X-ray diffraction (XRD) by deforming the samples to different strain levels up to about 20%. A comparison of XRD-and EBSD-results revealed that the retained austenite grains at the surface have a stronger tendency to transform than the austenite grains in the bulk of the material.The deformation-induced changes of individual austenite grains before and after straining were monitored with EBSD. Three different types of austenite grains can be distinguished that have different transformation behaviors: austenite grains at the grain boundaries between ferrite grains, twinned austenite grains, and embedded austenite grains that are completely surrounded by a single ferrite grain. It was found that twinned austenite grains and the austenite grains present at the grain boundaries between larger ferrite grains typically transform first, i.e. are less stable, in contrast to austenite grains that are completely embedded in a larger ferrite grain. In the latter case, straining leads to rotations of the harder austenite grain within the softer ferrite matrix before the austenite transforms into martensite. The analysis suggests that austenite grain rotation behavior is also a significant contributing factor for enhancement of the ductility.

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Section: Austenite Grains At Ferrite Triple Junctionsmentioning

confidence: 87%

Deformation-induced austenite grain rotation and transformation in TRIP-assisted steel

et al. 2012

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“…Hecker et al (1982) and Murr et al (1982) investigated the influence of strain rate and strain state on deformation-induced tranformation in 304 stainless steel and developed a model for TRIP steel depending on the strain rate. The gradual transformation of austenite to strain induced martensite increases the work-hardening of these steels, which is desirable for the high formability because the onset of the necking is delayed, as explained by Shan et al (2008) and by for TRIP steels forming. As a consequence, these steels are commonly used * Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

Deep drawing simulation of a metastable austenitic stainless steel using a two-phase model

Gallée¹,

Pilvin²

2010

Journal of Materials Processing Technology

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“…However, bainitic ferrite and ferrite in the present steel have both the same crystallographic structure, bcc, and need further work to be able to be distinguished. In this work, a quantification of the amount of RA in the SZ carried out by considering an area of approximately 80 µm x 70 µm for EBSD, in the case of XRD diffraction the section exanimated was of 2mm 2 and finally the sample of the optical microscopy was 80 µm 2 . The results of these determinations are plotted in Figure 7 and compared with the ones found by OM and XRD.…”

Section: Microstructural Development In a Trip-780 Steel Joined By Frmentioning

confidence: 99%

“…Typical AHSS microstructures consist of mixtures of bainite (B), ferrite (F), martensite (M), and retained austenite (RA) [1]. In recent years these steels have been the subject of extensive work due to their relatively high toughness [2,3]. When AHSS are joined by friction stir welding (FSW), a precise characterization of the welded microstructures is of great importance as they account for the weld toughness [4].…”

Section: Introductionmentioning

confidence: 99%

Microstructural Development in a TRIP-780 Steel Joined by Friction Stir Welding (FSW): Quantitative Evaluations and Comparisons with EBSD Predictions

Medina¹,

Ferreira

Zambrano‐Robledo

et al. 2016

Soldag. insp.

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The present work describes the effect of FSW on the result microstructure in the stir zone (SZ), thermo-mechanically affected zone (TMAZ), heat affected zone (HAZ) and base metal (BM) of a TRIP-780 steel. X-ray diffraction (XRD), optical microscopy (OM) and EBSD were used for determinations retained austenite (RA) in the SZ, It was found that the amount of RA developed in SZ was relatively large, (approximately 11% to 15%). In addition, recrystallization and the formation of a grain texture were resolved using EBSD. During FSW, the SZ experienced severe plastic deformation which lead to an increase in the temperature and consequently grain recrystallization. Moreover, it was found that the recrystallized grain structure and relatively high martensite levels developed in the SZ lead to a significant drop in the mechanical properties of the steel. In addition, microhardness profiles of the welded regions indicated that the hardness in both the SZ and TMAZ were relatively elevated confirming the development of martensite in these regions. In particular, to evaluate the mechanical strength of the weld, lap shear tensile test was conducted; exhibited the fracture zone in the SZ with shear fracture with uniformly distributed elongation shear dimples.Key-words: AHSS; TRIP steel; XRD; EBSD; FSW. Microstructural Desenvolvimento em um Aço TRIP-780 Unido por Soldagem por Atrito com Pino Não Consumível (FSW): Comparações e Avaliações Quantitativas com EBSD PrediçõesResumo: O presente trabalho descreve o efeito do processamento FSW na microestrutura resultante na zona soldada, zona termomecanicamente afetada (TMAZ), zona afetada pelo calor (ZAC) e no metal base (MB) de um aço TRIP-780. Difração de raios-X (DRX), microscopia óptica (MO) e EBSD foram utilizados para a determinação de austenita retida (RA) na SZ. Verificou-se que a quantidade de RA desenvolvida na SZ foi relativamente grande, (cerca de 11% a 15%). Além disso, a recristalização e a formação de textura de grão foram resolvidas usando EBSD. Durante friction stir welding, FSW (Soldagem por Atrito com Pino Não-consumível), a SZ experimentou severa deformação plástica que conduziu a um aumento na temperatura e, consequentemente, recristalização dos grãos. Verificou-se que a estrutura do grão recristalizado e níveis relativamente elevados de martensita desenvolvidos na SZ, conduziram a uma redução significativa nas propriedades mecânicas do aço. Além disso, os perfis de microdureza das regiões soldadas indicam que a dureza, tanto na SZ como na TMAZ foi elevada, confirmando o desenvolvimento de martensita nestas regiões. Em particular, foi visualidade na zona fundida trincas alongadas em perfil y, distribuída uniformetente.

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Prediction of martensitic transformation and deformation behavior in the TRIP steel sheet forming

Cited by 63 publications

References 19 publications

Deformation-induced austenite grain rotation and transformation in TRIP-assisted steel

Deformation-induced austenite grain rotation and transformation in TRIP-assisted steel

Deep drawing simulation of a metastable austenitic stainless steel using a two-phase model

Microstructural Development in a TRIP-780 Steel Joined by Friction Stir Welding (FSW): Quantitative Evaluations and Comparisons with EBSD Predictions

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