Grain size altering yielding mechanisms in ultrafine grained high-Mn austenitic steel:Advanced TEM investigations

Chang-Yu Hung ¹Yu Bai ²Nobuhiro Tsuji ³Mitsuhiro Murayama⁴

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作者信息

1. Department of Materials Science and Engineering,Virginia Tech,Blacksburg,VA,24061,USA
2. Department of Materials Science and Engineering,Kyoto University,Yoshida-honmachi,Sakyo-ku,Kyoto,606-8501,Japan
3. Department of Materials Science and Engineering,Kyoto University,Yoshida-honmachi,Sakyo-ku,Kyoto,606-8501,Japan;Elements Strategy Initiative for Structural Materials,Kyoto University,Yoshida-honmachi,Sakyo-ku,Kyoto,606-8501,Japan
4. Department of Materials Science and Engineering,Virginia Tech,Blacksburg,VA,24061,USA;Institute for Materials Chemistry and Engineering,Kyushu University,Kasuga,Fukuoka,8168580,Japan
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Abstract

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 atmo-sphere 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.

Key words

Ultrafine grains/TWIP steel/Yield-drop phenomenon/Deformation twin nucleation/Structural defects/Transmission electron microscopy

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基金项目

authors would like to thank W.T.Reynolds at Virginia Tech for useful discussions.This study was partly conducted in the Nano()

a division of Institute for Critical Technology and Applied Sci-ence(ICTAS)at Virginia Tech,and used shared facilities at the Vi()

a member of the National Nanotechnology Coordinated Infrastructure(NNCI)()

supported by NSF(ECCS 1542100)

supported by NSF(2025151)

N.T.and M.M.greatly appreci-ate the financial support by the JST CREST(JPMJCR1994)

M.M.acknowledges a financial support by JSPS KAKENHI Grant Num-bers(19H02029)

M.M.acknowledges a financial support by JSPS KAKENHI Grant Num-bers(20H02479)

N.T.acknowledges a financial support by Elements Strategy Initiative for Structural Materials(ESISM)

N.T.acknowledges a financial support by Elements Strategy Initiative for Structural Materials(JPMXP0112101000)

Grant-in-Aid for Scientific Research(S)(15H05767)

and the Grant-in-Aid for Scientific Research(A)(20H00306)

all through the Ministry of Education,Culture,Sports,Science and Technology(MEXT),Japan()

出版年

2021

材料科学技术(英文版)

中国金属学会中国材料研究学会中国科学院金属研究所

材料科学技术(英文版)

CSTPCDCSCDSCI

影响因子：0.657

ISSN：1005-0302

被引量1

参考文献量61

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