文献类型：期刊文献

英文题名：Enhancing the Hydrogen Embrittlement Resistance of Medium Mn Steels by Designing Metastable Austenite with a Compositional Core-shell Structure

作者：Zhang, Jun[1];Sun, Binhan[2];Yang, Zhigang[1];Zhang, Chi[1];Chen, Hao[1]

机构：[1]Tsinghua Univ, Sch Mat Sci & Engn, Key Lab Adv Mat, Minist Educ, Beijing 100084, Peoples R China;[2]East China Univ Sci & Technol, Sch Mech & Power Engn, Key Lab Pressure Syst & Safety, Minist Educ, Shanghai 200237, Peoples R China

年份：2023

卷号：36

期号：7

起止页码：1059

外文期刊名：ACTA METALLURGICA SINICA-ENGLISH LETTERS

收录：;EI(收录号：20224513070408);WOS:【SCI-EXPANDED(收录号:WOS:000879270800001)】；

基金：H. Chen acknowledges financial support from the National Natural Science Foundation of China (Nos. 51922054, U1860109 and U1808208) and the National Key Research and Development Program of China (2022YFE0110800). Z.G. Yang acknowledges financial support from the National Natural Science Foundation of China (No. 52171008). B. Sun acknowledges financial support from the National Natural Science Foundation of China (No. 52275147).

语种：英文

外文关键词：Medium Mn steels; Hydrogen embrittlement; Core-shell austenite; Chemical heterogeneity; Deformation-induced martensite transformation

摘要：Deformation-induced martensite transformation from metastable retained austenite is one of the most efficient strain-hardening mechanisms contributing to the enhancement of strength-ductility synergy in advanced high-strength steels. However, the hard transformation product (often alpha'-martensite) and the H redistribution associated with phase transformation essentially decrease materials' resistance to hydrogen embrittlement. To solve this fundamental conflict, we introduce a new microstructure architecting strategy based on an accurately design of core-shell compositional distribution inside the austenite phase. We employed this approach in a typical medium Mn steel (8 wt.% Mn) with an ultrafine grained austenite-ferrite microstructure. We produced a high Mn content (15-16 wt.%) in the austenite shell region and a low Mn content (similar to 12 wt.%) in the core region, through a thermodynamics-guided two-step austenite reversion treatment. During room-temperature deformation, the austenite core transforms continuously starting from a low strain, providing a high and persistent strain-hardening rate. The transformation of Mn-rich austenite shell, on the other hand, occurs only at the latest regime of the deformation, thus effectively inhibiting the nucleation of H-induced cracks at ferrite/deformation-induced martensite interfaces as well as suppressing their growth and percolation. This step-wise transformation, tailored directly targeted to protect the hydrogensensitive microstructure defects (interfaces), results in a significantly enhanced hydrogen embrittlement resistance without sacrificing the mechanical performance in hydrogen-free condition. The design of compositional core-shell structure is expected to be applicable to, at least, other multiphase advanced high-strength steels containing metastable austenite.