Influence of Plastic Deformation on Thermal Stability of Low Carbon Bainitic Steel

作     者：Chao SUN Shan-wu YANG Rui ZHANG Xian WANG Hui GUO 

作者机构：School of Materials Science and EngineeringUniversity of Science and Technology Beijing 

出 版 物：《Journal of Iron and Steel Research International》 (国际钢铁研究杂志)

年 卷 期：2015年第22卷第1期

页      面：60-66页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：Sponsored by National Natural Science Foundation of China(50671016) National Basic Research Program of China(2010CB630801) 

主　　题：bainite thermal stability plastic deformation compression torsion 

摘      要：Bainite is metastable due to its high dislocation density, and consequently bainitic steel structures have the problem of thermal stability. Plastic deformation of bainite can further increase dislocation density and change dislo- cation configuration at the same time. The influence of plastic deformation on thermal stability of low carbon bainitic steel during isothermal holding at 650 ℃ was investigated with hardness analysis, in-situ tracing metallographic analysis and transmission electron microscopy, Bainite in the low carbon steel evolves into polygonal ferrite via recov- ery and reerystallization during isothermal holding at 650 ℃. There is a considerably long period （about 20 h） be tween end of recovery and commencement of recrystallization of undeformed bainite, in which the hardness of the sample maintains a constant value slightly lower than that before reheating. Slight plastic deformation of bainite in- duces rearrangement of pre existing dislocations and forming of low-energy dislocation cells inside bainite laths, which has little influence on thermal stability of bainite, whereas heavy plastic deformation results in obvious dislocation multiplication and accelerates recrystallization of bainite. Recrystallization of heavily-deformed bainite occurs preferen tially at prior austenite grains boundaries. The samples subjected to heavy torsion exhibit obviously higher thermal stability than the samples subjected to heavy compression despite their same initial hardness, which can be attributed to different influences of torsion and compression on dislocations and boundaries of bainite.