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Open AccessArticle

In Situ Neutron Diffraction Study of Phase Transformation of High Mn Steel with Different Carbon Content

1
Department of Materials Science and Engineering, Chungnam National University, Daejeon 34134, Korea
2
Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
3
Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
4
Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 34134, Korea
*
Author to whom correspondence should be addressed.
Crystals 2020, 10(2), 101; https://doi.org/10.3390/cryst10020101
Received: 22 December 2019 / Revised: 5 February 2020 / Accepted: 6 February 2020 / Published: 10 February 2020
In situ neutron diffraction was employed to examine the phase transformation behavior of high-Mn steels with different carbon contents (0.1, 0.3, and 0.5 wt.%C). With increasing carbon contents from 0.1 C to 0.5 C, the austenite phase fraction among the constituent phases increased from ~66% to ~98%, and stacking fault energy (SFE) increased from ~0.65 to ~16.5 mJ/m2. The 0.1 C and 0.3 C steels underwent phase transformation from γ-austenite to ε-martensite or α’-martensite during tensile deformation. On the other hand, the 0.5 C steel underwent phase transformation only from γ-austenite to ε-martensite. The 0.3 C steel exhibited a low yield strength, a high strain hardening rate, and the smallest elongation. The high strain hardening of the 0.3 C alloy was due to a rapid phase transformation rate from γ-austenite to ε-martensite. The austenite of 0.5 C steel was strengthened by mechanical twinning during loading process, and the twinning-induced plasticity (TWIP) effect resulted in a large ductility. The 0.5 wt.% carbon addition stabilized the austenite phase by delaying the onset of the ε-martensite phase transformation.
Keywords: High Mn steel; phase transformation; carbon; stacking fault energy; neutron diffraction High Mn steel; phase transformation; carbon; stacking fault energy; neutron diffraction
MDPI and ACS Style

Kim, Y.; Choi, W.; Choo, H.; An, K.; Choi, H.-S.; Lee, S.Y. In Situ Neutron Diffraction Study of Phase Transformation of High Mn Steel with Different Carbon Content. Crystals 2020, 10, 101.

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