摘要
贝氏体碳化物有θ-Fe3C、ε-Fe2.4C两类,其形成机理至今没有搞清,且有学术论争。本文通过对P20钢、718钢、23MnNiCrMo钢等钢贝氏体碳化物的电镜观察和理论分析,表明:贝氏体铁素体中的碳原子是过饱和的,过饱和度约小于0.2%C。在铁素体内部不具备形成碳化物的条件。依靠碳原子的长程扩散和铁原子的热激活迁移,贝氏体碳化物在BF/γ相界面上形核,并沿着相界面长大,可以长入铁素体亚单元之间,或长入奥氏体中,碳化物停止长大后可被铁素体包围。贝氏体碳化物形成过程中,铁原子和替换原子的迁移是热激活的界面控制过程。
The bainite carbide have two types, θ-Fe3C and ε-Fe2.4 C, the formation mechanism of which hasnt been studied clearly and there still some disputes exist. TEM observation was used to study P20 steel,718 steel,23MnNiCrMo steel in this paper. The results show that the carbon atom of bainitic ferrite is supersaturated. The supersaturation degree is less than 0.2% C. It hasn＇t provided the condition with carbide formation inside the ferrite. Bainitic carbide nucleated by means of the long - range diffusion of carbon atoms and the thermal activation transition of iron atoms at phase interface of BF/γ and grow up into the sub - cell of bainitic carbide or austenite along interface, when the carbide stopped the growth it would be besieged by the ferrite. The transfer ways of iron atoms and substitution atoms were the interface control processes that by thermal activation transition method during the formation process of bainitic carbide.
出处
《热处理技术与装备》
2007年第4期19-23,共5页
Heat Treatment Technology and Equipment
基金
内蒙内自治区高等学校科学研究项目:NJ06073
关键词
贝氏体
碳化物
扩散
整合
热激活迁移
bainite
carbide
diffusion
integrate in a systematic way
thermal activation transition
