Thermal stability of retained austenite in TRIP steels studied by synchrotron X-ray diffraction during cooling

Dijk, Niels van; Butt, Anum; Zhao, L.; Sietsma, Jilt; Offerman, S.E.; Wright, Jonathan P.; Zwaag, Sybrand van der

doi:10.1016/j.actamat.2005.08.017

Cited by 495 publications

(221 citation statements)

References 7 publications

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“…Therefore, several studies were carried out to reveal the deformation behavior of retained austenite in TRIP steels [7][8][9]. Experimental investigations showed that the austenite stability is affected by: (i) the constraining effect from the phases surrounding the retained austenite [10], (ii) the crystallographic orientation of grains with respect to the loading direction [11], (iii) the local carbon concentration in the austenite [12] and (iv) the grain volume of the retained austenite grains [14]. It has also been observed in these steels that the deformation behavior depends on the morphology of two types of retained austenite grains.…”

Section: Introductionmentioning

confidence: 99%

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: Introductionmentioning

confidence: 99%

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

et al. 2012

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“…where a 0 is the theoretical austenite lattice parameter (at 20°C) for pure iron, being 3.556 Å , [23] X C is the concentration of carbon in wt pct, X Mn is the concentration of manganese in wt pct, and k C and k Mn are determined to be 0.00453 nm/(wt pct) C and 0.000095 nm/(wt pct) Mn as indicated in Reference 23, respectively. The calculated carbon content of retained austenite is higher within the samples subjected to higher loads (Table III).…”

Section: Retained Austenitementioning

confidence: 99%

“…Volume fractions of the phases and austenite lattice parameters were acquired from the integrated intensities and the scattering angles of two austenite (c (200) and c (220) ) and two bcc (a (200) and a (211) ) phase rings. [23] Typical intensity-2h patterns of c (220) and a (211) at different times during cooling are shown in Figure 6, and these were used for volume fraction calculations. The bcc phases include several ferrite products such as grain boundary ferrite, Widmansta¨tten ferrite, bainitic ferrite, and also martensite.…”

Section: Experimental Approachmentioning

confidence: 99%

In-Situ Synchrotron X-ray Diffraction Studies on Effects of Plastic and Elastic Loading on bcc Phase Transformations of a 3rd Generation 1 GPa Advanced High Strength Steel

Eftekharimilani

Huizenga

Kim

et al. 2017

Metall Mater Trans A

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In this paper, we describe the effects of mechanical loading on bcc-to-bcc phase transformations of an Advanced High Strength Steel during cooling. In-situ synchrotron diffraction was employed to measure time-temperature-load diffraction patterns. Calculations were made of the volume fractions of the phases, the transformation kinetics, and the austenite lattice parameter during cooling and simultaneous loading. In addition, volume fractions and lattice parameters of retained austenite at room temperature under different loading conditions were obtained. The results show that applying a load during cooling of the fcc phase significantly increases the volume fraction of a bcc phase before the start of the martensitic transformation. The kinetics of phase transformations were affected by the applied loads. The volume fraction and lattice parameter of retained austenite at room temperature vary in different samples and the highest retained austenite and the largest lattice parameter were obtained in the sample subjected to the highest load.

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“…In the literature several factors affecting the martensitic transformation are given: (1) the local carbon concentration in austenite, [8] (2) the grain size of the austenite grains, [9] (3) the crystallographic orientation of austenite grains with respect to the loading direction, [10] and (4) the position of the austenite grains within the ferrite matrix [11]. The above four factors were also closely assessed for these grains with the help of EBSD and EPMA analysis.…”

mentioning

confidence: 99%

“…The concept of deformation-induced phase transformation has also been applied to polymers [5], brittle bulk metallic glasses [6] and very recently to titanium-based biomedical alloys [7]. In view of the technological importance there is a strong interest in understanding deformation-induced phase transformations, in particular to assess the role of various microstructural parameters such as the local chemical composition [8], grain size [9], crystal lattice orientation in relation to strain direction [10] and the location of the grain in relation to its surrounding grains [11]. An accurate understanding of all these factors and their interplay will allow fine tuning of phase transformations resulting in an enhanced control over the material properties [12].…”

mentioning

confidence: 99%

Unravelling the structural and chemical features influencing deformation-induced martensitic transformations in steels

Tirumalasetty¹,

Huis²,

Kwakernaak³

et al. 2014

Scripta Materialia

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Thermal stability of retained austenite in TRIP steels studied by synchrotron X-ray diffraction during cooling

Cited by 495 publications

References 7 publications

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

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

In-Situ Synchrotron X-ray Diffraction Studies on Effects of Plastic and Elastic Loading on bcc Phase Transformations of a 3rd Generation 1 GPa Advanced High Strength Steel

Unravelling the structural and chemical features influencing deformation-induced martensitic transformations in steels

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