等温处理对新型高强钢力学性能和绝热剪切行为的影响

为了使新型高强钢更好地在冲击领域得到应用，采用等温盐浴方法对新型高强度钢进行热处理.通过OM、SEM、TEM对材料的微观组织进行观察，采用万能试验机对材料进行准静态拉伸力学性能测试，通过分离式霍普金森压杆（SHPB）对材料进行动态性能测试并捕捉临界应变率下萌生发展的绝热剪切带形貌.研究结果表明:随着等温温度的升高，对应材料的主要组织由马氏体+下贝氏体，马氏体+下贝氏体+上贝氏体变化为马氏体+上贝氏体，材料的屈服强度和塑性逐渐降低.330℃等温处理的材料绝热剪切带萌生的临界应变率为3种等温处理材料中最低，上贝氏体组织的出现使材料对绝热剪切变形的敏感性降低. 

Isothermal Heat Treatment on Mechanical Properties and Adiabatic Shear Behavior of a New High-Strength Steel

To make a new high strength steel be better applied in impacting environment, an isothermal salt bath method was proposed for its heat treatment. The microstructure of the material was observed by OM,SEM and TEM. The quasi-static tensile properties were tested by a universal testing machine and the dynamic properties were tested by split Hopkinson pressure bar (SHPB). Meanwhile the nucleation of adiabatic shear bands (ASBs) under critical strain rates was obtained. Experimental results show that, with the increasing of isothermal temperature, the main microstructure is changed from martensite+lower bainite, martensite+lower bainite+upper bainite to martensite+upper bainite, and the yield stresses and toughnesses decline gradually. The critical strain rate for the nucleation of ASBs of the steel treated at 330℃ isothermal temperature is the lowest. The appearance of upper bainite makes the high strength steel less sensitive to the nucleation of adiabatic shear bandings.