摘要
对 Fe-C-Mn 系亚共析钢在临界区退火时奥氏体的体积分数和成分分布的变化规律作计算机模拟和实验研究。结果表明:(1)奥氏体长大第一阶段体系处于伸平衡状态。(2)第二阶段初期体系处于局部平衡,后期过渡到全平衡状态;这一阶段 J_(mn)^(āb)>J_(Υb)^(mn),锰和碳在新生成的Υ相中富集。当 J_(mn)^(ab)=J_(mn)^(Υb)时,这一阶段结束。(3)第三阶段在全平衡状态下进行,动力学特征是J_(mn)^(Υb)>J_(mn)^(ab)这一阶段,Υ相发生体积收缩。
A model for the diffusion controlled austenite growth during intercriti- cal annealing of Fe-C-Mn low carbon low alloy steels was developed by ap- plying the concepts of paralocal,and full-equilibrium and the law of mass balance to the description of the austenite/ferrite interface conditions,the movement rate of the interface and the concentration profiles in austenite. The diffusion of Mn and C was determined with the aid of Onsager's exten- sion of Fick's first law.Caculations were made for a 0.08-1.43Mn and a 0.06-1.5Mn steels.It has been concluded that: (1)During the first stage of austenite growth,the system was in the para-equilibrium state. (2)During the early period of the second stape,the system maintained the local-equilibrium state.Later,it proceeded to the full-equilibrium one as the diffusion of Mn extended to the center of austenite phase.Both Mn and C were enriched in the newly-formed austenite.This stage came to the end when J_(mn)^(ab)=J_(mn)^(γb). (3)The third stage was characterized by J_(mn)^(γb)>J_(mn)^(ab).During thia stage, the system was in the full-equilibrium state and the austenite shrinkaged.
关键词
FeCMn钢
亚共析钢
监界区
奥氏体
Fe-C-Mn steel
austenite growth
diffusion
controlled phase transformation diffusion in multicomponent
