Dual nanoprecipitation and nanoscale chemical heterogeneity in a secondary hardening steel for ultrahigh strength and large uniform elongation  

作　　者：Shidong Wang Jinhua Wang Shijie Zhang Daixiu Wei Yang Chen Xuequan Rong Wu Gong Stefanus Harjo Xiaochun Liu Zengbao Jiao Zhigang Yang Gang Sha Chunxu Wang Guang Chen Hao Chen 

机构地区：[1]Key Laboratory for Advanced Materials of Ministry of Education,School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China [2]School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience,Nanjing University of Science and Technology,Nanjing 210094,China [3]National Key Laboratory of Advanced Casting Technologies,MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology,Engineering Research Center of Materials Behavior and Design,Ministry of Education,Nanjing University of Science and Technology,Nanjing 210094,China [4]J-PARC Center,Japan Atomic Energy Agency,Ibaraki 319-1195,Japan [5]Institute of Metals,College of Materials Science and Engineering,Changsha University of Science&Technology,Changsha 410114,China [6]Department of Mechanical Engineering,Research Institute for Advanced Manufacturing,The Hong Kong Polytechnic University,Hong Kong 999077,China [7]Central Iron and Steel Research Institute,Beijing 100081,China

出　　处：《Journal of Materials Science & Technology》2024年第18期245-258,共14页材料科学技术（英文版）

基　　金：Z.G.Yang acknowledges financial support from the National Key R&D program of China(grant No.2022YFB3705200);National Natural Science Foundation of China(grant No.52171008);H.Chen acknowledges financial support from the National Natural Science Foundation of China(grant No.51922054);Tsinghua University Initiative Scientific Research Program(No.20233080002);the Mobility Programme from the Sino-German Center(Grant No.M-0319).

摘　　要：Nanoprecipitates and nanoscale retained austenite(RA)with suitable stability play crucial roles in deter-mining the yield strength(YS)and ductility of ultrahigh strength steels(UHSSs).However,owing to the kinetics incompatibility between nanoprecipitation and austenite reversion,it is highly challenging to si-multaneously introduce high-density nanoprecipitates and optimized RA in UHSSs.In this work,through the combination of austenite reversion treatment(ART)and subsequent flash austenitizing(FA),nanoscale chemical heterogeneity was successfully introduced into a low-cost UHSS prior to the aging process.This chemical heterogeneity involved the enrichment of Mn and Ni in the austenite phase.The resulting UHSS exhibited dual-nanoprecipitation of Ni(Al,Mn)and(Mo,Cr)_(2)C and nanoscale austenite stabilized via Mn and Ni enrichment.The hard martensitic matrix strengthened by high-density dual-nanoprecipitates con-strains the plastic deformation of soft RA with a relatively low fraction of-15%,and the presence of relatively stable nanoscale RA with adequate Mn and Ni enrichment leads to a marginal loss in YS but keeps a persistent transformation-induced plasticity(TRIP)effect.As a result,the newly-developed UHSS exhibits an ultrahigh YS of-1.7 GPa,an ultimate tensile strength(UTS)of-1.8 GPa,a large uniform elongation(UE)of-8.5%,and a total elongation(TE)of-13%.The strategy of presetting chemical heterogeneity to introduce proper metastable phases before aging can be extended to other UHSSs and precipitation-hardened alloys.

关 键 词：Ultrahigh strength steels Dual-nanoprecipitation Austenite stability TRIP effect Phase transformation 

分 类 号：TG178[金属学及工艺—金属表面处理]