Nano-scale observation on the transformation behavior and mechanical stability of individual retained austenite in CMnSiAl TRIP steels

Park, Hyoung Seok; Han, Jong Chan; Lim, Nam Suk; Seol, Jae Bok; Park, Chan Gyung

doi:10.1016/j.msea.2015.01.005

Cited by 92 publications

(37 citation statements)

References 24 publications

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“…This means that the thermal stability of film-type or lath-type RA grains is lower than that of blocky-type RA for the present steels. It is noteworthy that prior to the tempering (in as-received state), fully decomposed film-type RA and partially decomposed blocky-type RA grains were not detected [28]. In this study, TEM result reflects two controversial findings.…”

Section: Microstructure Characterizationmentioning

confidence: 61%

“…First, it was generally reported that lath-type or film-type RA grains were found to be mechanically more stable and were transformed more constantly against mechanical deformation, compared to blocky-type RA grains [29,30]. Recent experimental approaches using APT and nanoindentation confirmed that the retardation of martensite transformation under external stress resulted from higher carbon contents of film-type RA grains than those of blocky-type RA [28]. Second, the mechanical stability of metastable RA can be generally controlled by its size (called constraining effect) [31].…”

Section: Microstructure Characterizationmentioning

confidence: 99%

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Study of the decomposition behavior of retained austenite and the partitioning of alloying elements during tempering in CMnSiAl TRIP steels

et al. 2015

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Section: Microstructure Characterizationmentioning

confidence: 61%

Section: Microstructure Characterizationmentioning

confidence: 99%

Study of the decomposition behavior of retained austenite and the partitioning of alloying elements during tempering in CMnSiAl TRIP steels

et al. 2015

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“…It indicated that the multi-phase microstructure had good thermal stability upon high-temperature tempering. 20 kV. After SEM observation, samples were ground and electron-polished to determine the volume fraction of the retained austenite by X-ray diffraction (XRD).…”

Section: Experimental Materials and Proceduresmentioning

confidence: 99%

Thermal Stability of Retained Austenite and Properties of A Multi-Phase Low Alloy Steel

Xie

Xiong

Han

et al. 2018

Metals

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In this work, we elucidate the effects of tempering on the microstructure and properties in a low carbon low alloy steel, with particular emphasis on the thermal stability of retained austenite during high-temperature tempering at 500–700 °C for 1 h. Volume fraction of ~14% of retained austenite was obtained in the studied steel by two-step intercritical heat treatment. Results from transmission electron microscopy (TEM) and X-ray diffraction (XRD) indicated that retained austenite had high thermal stability when tempering at 500 and 600 °C for 1 h. The volume fraction was ~11–12%, the length and width remained ~0.77 and 0.21 μm, and concentration of Mn and Ni in retained austenite remained ~6.2–6.6 and ~1.6 wt %, respectively. However, when tempering at 700 °C for 1 h, the volume fraction of retained austenite was decreased largely to ~8%. The underlying reason could be attributed to the growth of austenite during high-temperature holding, leading to a depletion of alloy contents and a decrease in stability. Moreover, for samples tempered at 700 °C for 1 h, retained austenite rapidly transformed into martensite at a strain of 2–10%, and a dramatic increase in work hardening was observed. This indicated that the mechanical stability of retained austenite decreased.

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“…Aside from the crystal orientation, the required driving force is also a function of RA present within the material. This is most clearly demonstrated from results produced by Zhirafar et al and Park et al In order to capture this phenomenon within the model, as the volume fraction of austenite decreases towards zero, the energy requirement is modified by an assumed relationship of the initial volume fraction of austenite divided by the current volume fraction of austenite present

((), \frac{V_{f, italicinitial}}{V_{f}})

. This is applied to represent increasing energy requirements for transformations as less RA is present in the material.…”

Section: Driving Force Variationmentioning

confidence: 99%

“…Dommarco et al was able to demonstrate similar results in 52100 steel utilizing a modified 3 ball and rod testing apparatus. Distinguishing between bulk and lathe or film RA, Park et al observed phase transformations in steel as a function of strain. They demonstrated that bulk type RA, typically larger than lathe and situated between or inside ferrite grains, more readily transforms compared with lathe type distributed along martensitic grain boundaries.…”

Section: Introductionmentioning

confidence: 99%

A novel approach for modeling retained austenite transformations during rolling contact fatigue

Sadeghi

Chen

Wang

et al. 2017

Fatigue Fract Eng Mat Struct

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Retained austenite (RA) transformation in martensitic steels subjected to rolling contact fatigue (RCF) is a well‐established phenomenon. In this investigation, a novel approach is developed to predict martensitic transformations of RA in steels subjected to RCF. In order to achieve the objectives, a 2‐dimensional finite element model was developed to determine subsurface stresses due to rolling contact. These stresses are utilized within a continuum damage mechanics framework to determine RA transformations as a function of depth and cycles. Phase transformations were determined by comparing the required thermodynamic driving force for transformations to the energy dissipation of the microstructure. The results obtained from the combined FEA and continuum damage mechanics model were corroborated to the experimental results for RA decomposition as a function of depth and cycle for SAE 52100 steel. The results obtained are in good agreement with observed RA decomposition and DER formation as compared with the experimental results.

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Nano-scale observation on the transformation behavior and mechanical stability of individual retained austenite in CMnSiAl TRIP steels

Cited by 92 publications

References 24 publications

Study of the decomposition behavior of retained austenite and the partitioning of alloying elements during tempering in CMnSiAl TRIP steels

Study of the decomposition behavior of retained austenite and the partitioning of alloying elements during tempering in CMnSiAl TRIP steels

Thermal Stability of Retained Austenite and Properties of A Multi-Phase Low Alloy Steel

A novel approach for modeling retained austenite transformations during rolling contact fatigue

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