Deformation mechanisms for a new medium-Mn steel with 1.1 GPa yield strength and 50% uniform elongation  

作　　者：Wei Wang Yanke Liu Zihan Zhang Muxin Yang Lingling Zhou Jing Wang Ping Jiang Fuping Yuan Xiaolei Wu 

机构地区：[1]State Key Laboratory of Nonlinear Mechanics,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China [2]School of Engineering Sciences,University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Journal of Materials Science & Technology》2023年第1期110-118,共9页材料科学技术（英文版）

基　　金：supported by the National Key R&D Pro-gram of China(No.2017YFA0204402);the NSFC Basic Science Cen-ter Program for“Multiscale Problems in Nonlinear Mechanics”(No.11988102);the National Natural Science Foundation of China(Nos.11790293 and 52192591).

摘　　要：A new medium-Mn steel was designed to achieve unprecedented tensile properties,with a yield strength beyond 1.1 GPa and a uniform elongation over 50%.The tensile behavior shows a heterogeneous deforma-tion feature,which displays a yield drop followed by a large Lüders band strain and several Portevin-Le Châtelier bands.Multiple strain hardening mechanisms for excellent tensile properties were revealed.Firstly,non-uniform martensite transformation occurs only within a localized deformation band,and ini-tiation and propagation of every localized deformation band need only a small amount of martensite transformation,which can provide a persistent and complete transformation-induced-plasticity effect dur-ing a large strain range.Secondly,geometrically necessary dislocations induced from macroscopic strain gradient at the front of localized deformation band and microscopic strain gradient among various phases provide strong heter-deformation-induced hardening.Lastly,martensite formed by displacive shear trans-formation can inherently generate a high density of mobile screw dislocations,and interstitial C atoms segregated at phase boundaries and enriched in austenite play a vital role in the dislocation multipli-cation due to the dynamic strain aging effect,and these two effects provide a high density of mobile dislocations for strong strain hardening.

关 键 词：Medium-Mn steel Strain hardening DUCTILITY Martensite transformation Strain gradient Mobile dislocations 

分 类 号：TG142.1[一般工业技术—材料科学与工程]