Accelerating bainite transformation by concurrent pearlite formation in a medium Mn steel:Experiments and modelling  

作　　者：L.K.Huang F.Liu M.X.Huang 

机构地区：[1]Department of Mechanical Engineering,The University of Hong Kong,Pokfulam Road,Hong Kong,China [2]State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi’an,Shaanxi,710072,China

出　　处：《Journal of Materials Science & Technology》2024年第9期211-223,共13页材料科学技术（英文版）

基　　金：support from National Key Research and Development Program of China(No.2019YFA0209900);National Natural Science Foundation of China(No.52130102);Research Grants Council of Hong Kong(No.R7066–18);Guangzhou Municipal Science and Technology Project(No.202007020007);Guangdong Basic and Applied Basic Research Foundation of China(No.2020B1515130007);support from National Natural Science Foundation of China(No.52130110);support from National Natural Science Foundation of China(No.52271116);Hong Kong Scholars Program(No.XJ2019029).

摘　　要：Bainite transformation has yet to be utilized and even thoroughly studied in medium Mn steels.Here,we investigate the isothermal bainite transformation in a 10Mn steel at 450°C experimentally and theoretically,focusing on the effect of dislocations introduced by warm deformation.We show that the bainite transformation in the studied medium Mn steel exhibits extremely sluggish kinetics(on a time scale of days),concurrent with the pearlite formation.The introduced dislocations can significantly accelerate bainite transformation kinetics while also facilitating the pearlite reaction.This is likely the first report on the simultaneous occurrence of these two solid-state reactions in medium Mn steels.With respect to the roles of dislocations in the acceleration of bainite transformation observed in this work,we propose a new‘carbon depletion mechanism’,in which dislocations-stimulated pearlite formation makes a twofold contribution:facilitating the formation of bainitic ferrite sub-units to further enhance the autocatalytic effect and preventing the carbon enrichment in the remaining austenite.On this basis,a physical model is developed to quantitatively understand the bainite transformation kinetics considering the effect of concurrent pearlite formation,revealing good agreements between model descriptions and experiment results.Our findings,herein,offer fundamental insights into the bainite transformation in medium Mn steels and uncover a previously unidentified role played by introduced dislocations in influencing the kinetics of bainite formation,which may guide its future application in manipulating microstructure for the development of advanced high-strength steels.

关 键 词：Medium Mn steels BAINITE THERMODYNAMICS Kinetics Phase transformation 

分 类 号：TG142[一般工业技术—材料科学与工程]