固溶强化FeCrNi合金塑性变形机制探讨

Plastic Deformation Mechanism of Solid Solution Hardened FeCrNi Alloy

采用万能材料试验机和分离式霍普金森压杆对氮固溶强化的FeCrNi合金进行了不同温度下的准静态和动态力学试验,研究了温度和应变速率对FeCrNi合金力学性能的影响。结果表明：由于氮固溶强化原子的本征势垒△G_0较低,使FeCrNi合金在准静态下热激活应力为零时的临界温度T_c小于非热应力的失稳温度T_c,这时流变应力-温度曲线出现平台区；而在高应变速率时,T_c大于T_c,使平台区消失；在室温至600K之间存在的退火孪晶对非热应力和热激活应力均产生影响,随着温度的升高,退火孪晶逐渐消失,使得非热应力和热激活应力明显下降。

Using versatile material test machine and split Hopkinson pressure bar （SHPB）, quasi-static and dynamic mechanical tests of FeCrNi alloy were carried out, the effect of temperature and strain rate on mechanical properties was investigated. The small AGo of solid solution hardening nitrogen atom made the therrnally activated critical temperature T~ lower than the critical descend temperature Te of athermal stress, which resulted in a platform in the quasi-static flow-stress-temperature curve at 573--900 K. But high strain rate made Tc higher than Te′, the platform disappeared. A large mount of annealing twins affected both athermally and thermally activated stresses. The twins disappear as temperature was elevated from room temperature to about 600 K, which made the two kinds of stress all descend dramatically in this temperature region.