Stability of Ultra-fine Microstructures during Tempering

作     者：Shanwu Yang, Chengjia Shang,Xinlai He, Xuemin Wang, Yi Yuan (Material Science and Engineering School, University of Science and Technology Beijing, Beijing 100083, China) 

作者机构：Univ Sci & Technol Beijing Mat Sci & Engn Sch Beijing 100083 Peoples R China 

出 版 物：《Journal of University of Science and Technology Beijing》 (北京科技大学学报（英文版）)

年 卷 期：2001年第8卷第2期

页      面：119-122页

核心收录：

学科分类：080503[工学-材料加工工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0802[工学-机械工程] 080201[工学-机械制造及其自动化] 

主　　题：microalloyed steel bainite tempering 

摘      要：The stability of ultra-fine microstructure during tempering at 650 degreesC was investigated on a Nb-containing steel. The steel had undergone 5 passes controlled rolling, then was relaxed lair cooled) to 730 degreesC: and cooled in water. The evolution of microstructure was that, in early stage of tempering, no obvious change was detected by means of optical microscopy while dislocation cells were formed inside bainitic laths. With further tempering, bainitic laths started to coalesce in some regions. Finally, polygonal ferrite was formed while hardness decreased dramatically. Some samples taken from the same primary plate were reheated at 930 degreesC for 0.5 h followed by quenching into water before tempering. Despite their lower original hardness, the reheated samples softened Faster during tempering. Ferrite was quickly formed in the reheated samples. These results indicate that the evolution of microstructures towards equilibrium during tempering of the steel is mainly determined by whether dislocations are pinned rather than the dislocation density.