SAE9310钢动态再结晶临界条件的研究

Critical Strain of Dynamic Recrystallization in SAE9310 Steel

应用加工硬化理论探讨了SAE9310钢在大应变条件下的加工硬化率曲线及动态再结晶的拐点判据，根据在变形温度为900～1200℃、应变速率为0．01～10s。条件下的等温恒应变速率压缩实验，采用拐点判据方法和金相观察手段，研究了SAE9310钢发生动态再结晶的临界条件，建立了该钢的动态再结晶状态图。结果表明，在本实验条件下，SAE9310钢的流变曲线呈现两种特征类型；发生动态再结晶的临界应变εc，和临界应力αc均随应变速率的增大和变形温度的降低而增加；临界应变与峰值应变之间满足εc／εp=0．30～0．42；随着Z参数的增加，临界变形量增大，材料发生动态再结晶变得困难。

Based on the theory of work hardening, the curve of work hardening rate under large strain and inflection point criterion of dynamic recrystallization in SAE9310 steel were researched at deformation temperature from 900℃ to 1200% and strain rate from 0. 01 s^-1 to 10s^-1. By means of inflection point criterion and metallographic observation, the critical condition of dynamic recrystallization in SAE9310 steel was demonstrated and the dynamic recrystallization state diagram was established. The results indicate that two types of stress-strain curve is observed under the present deformation conditions. During dynamic recrystallization the critical strain εc and critical stress σc increase with strain rate increasing and deformation temperature decreasing. A certain correlation between critical strain εc and peak strain εp is according with εc/εp = 0.30 - 0.42. The critical deformation increases and the dynamic reerystallization for the material becomes more difficult with parameters Z increasing.