TY - JOUR
T1 - Grain size altering yielding mechanisms in ultrafine grained high-Mn austenitic steel
T2 - Advanced TEM investigations
AU - Hung, Chang Yu
AU - Bai, Yu
AU - Tsuji, Nobuhiro
AU - Murayama, Mitsuhiro
N1 - Funding Information:
The authors would like to thank W. T. Reynolds at Virginia Tech for useful discussions. This study was partly conducted in the Nanoscale Characterization and Fabrication Laboratory (NCFL), a division of Institute for Critical Technology and Applied Science (ICTAS) at Virginia Tech, and used shared facilities at the Virginia Tech National Center for Earth and Environmental Nanotechnology Infrastructure (NanoEarth), a member of the National Nanotechnology Coordinated Infrastructure (NNCI), supported by NSF (ECCS 1542100, 2025151). N.T. and M.M. greatly appreciate the financial support by the JST CREST (JPMJCR1994). M.M. acknowledges a financial support by JSPS KAKENHI Grant Numbers (19H02029, 20H02479). N.T. acknowledges a financial support by Elements Strategy Initiative for Structural Materials (ESISM, No. JPMXP0112101000), the Grant-in-Aid for Scientific Research (S) (No. 15H05767), and the Grant-in-Aid for Scientific Research (A) (No. 20H00306), all through the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.
Publisher Copyright:
© 2021
PY - 2021/9/30
Y1 - 2021/9/30
N2 - The underlying mechanism of discontinuous yielding behavior in an ultrafine-grained (UFG) Fe-31Mn-3Al-3Si (wt.%) austenitic TWIP steel was investigated by the use of advanced TEM technique with taking the plastic deformation mechanisms and their correlation with grains size near the macroscopic yield point into account. Typical yield drop mechanisms such as the dislocation locking by the Cottrell atmosphere due to the presence of interstitial impurities cannot explain the origin of this phenomenon in the UFG high-Mn austenitic TWIP steel. Here, we experimentally revealed that the plastic deformation mechanisms in the early stage of deformation, around the macroscopic yield point, show an obvious association with grain size. More specifically, the main mechanism shifts from the conventional slip in grain interior to twinning nucleated from grain boundaries with decreasing the grain size down to less than 1 μm. Our observation indicates that the grain size dependent deformation mechanisms transition is also deeply associated with the discontinuous yielding behavior as it could govern the changes in the grain interior dislocation density of mobile dislocations around the macroscopic yield point.
AB - The underlying mechanism of discontinuous yielding behavior in an ultrafine-grained (UFG) Fe-31Mn-3Al-3Si (wt.%) austenitic TWIP steel was investigated by the use of advanced TEM technique with taking the plastic deformation mechanisms and their correlation with grains size near the macroscopic yield point into account. Typical yield drop mechanisms such as the dislocation locking by the Cottrell atmosphere due to the presence of interstitial impurities cannot explain the origin of this phenomenon in the UFG high-Mn austenitic TWIP steel. Here, we experimentally revealed that the plastic deformation mechanisms in the early stage of deformation, around the macroscopic yield point, show an obvious association with grain size. More specifically, the main mechanism shifts from the conventional slip in grain interior to twinning nucleated from grain boundaries with decreasing the grain size down to less than 1 μm. Our observation indicates that the grain size dependent deformation mechanisms transition is also deeply associated with the discontinuous yielding behavior as it could govern the changes in the grain interior dislocation density of mobile dislocations around the macroscopic yield point.
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U2 - 10.1016/j.jmst.2021.01.031
DO - 10.1016/j.jmst.2021.01.031
M3 - Article
AN - SCOPUS:85102400709
VL - 86
SP - 192
EP - 203
JO - Journal of Materials Science and Technology
JF - Journal of Materials Science and Technology
SN - 1005-0302
ER -