初始组织对电脉冲处理逆变奥氏体晶粒细化效果的影响  

Effect of starting microstructure on refining potency of electro-pulsing on reverse austenite grain

作　　者：张家陶[1] 赵宇光[1] 谭娟[1] 

机构地区：[1]吉林大学材料科学与工程学院,长春130022

出　　处：《吉林大学学报（工学版）》2016年第1期193-198,共6页Journal of Jilin University:Engineering and Technology Edition

基　　金：国家自然科学基金项目(51071075)

摘　　要：通过金相组织观察、显微硬度测试,研究了电脉冲处理条件下,不同初始组织对逆变奥氏体晶粒细化效果的影响。结果表明:回火马氏体初始组织电脉冲奥氏体化过程为α+Fe_3C→γ扩散型逆相变,逆变奥氏体晶粒获得超细化(d_γ<5μm),这证实了脉冲电流促进奥氏体形核率提高的理论分析;马氏体初始组织电脉冲奥氏体化过程为α′→γ位移型逆相变;初始马氏体的原奥氏体晶界在逆相变过程中未发生变化,形成晶粒粗大的位移型逆变奥氏体;从位移型逆变奥氏体淬火得到的马氏体获得再次强化;升高电脉冲处理峰值温度,位移型逆变奥氏体发生再结晶;再结晶形核始于位移型逆变奥氏体晶界这唯一具有大角度位相差的区域;再结晶完成后,奥氏体平均晶粒直径为11μm。The influence of starting microstructure on the austenite grain refining potency in ElectroPulsing（EP）was investigated by microstructure observation and hardness testing.Results indicate that the mechanism of austenite formation from the starting tempered martensite during ElectroPulsing Treatment（EPT）is occurred by theα ＋ Fe3 C →γdiffusional transformation,and austenite grains are ultra-refined（dγ〈5μm）.This verifies the analysis that the austenite nucleation rate can be increased by EPT.However,the reverse transformation from martensite during EPT occurs by theα′→ γ displacive transformation process.The prior austenite grain boundaries of the starting martensite are not changed during the reverse transformation,leading to the formation of coarse grained Displacive Reverse Austenite（DRA）.Martensite transformed from DRA after quenching is strengthened.As the peak temperature is increased during EPT,the recrystallization of DRA is occurred.The nucleation recrystallization is started at the boundaries of DRA,where the high anglemicrostructure is only reversed after displacive reverse transformation.The mean size of the austenite grains is 11μm after recrystallization.

关 键 词：金属材料 逆相变 脉冲电流处理 晶粒细化 

分 类 号：TG161[金属学及工艺—热处理]