通过对挤压态42CrMo高强钢在不同温度和应变速率下的热压缩实验获得真应力-应变曲线,作为研究其高温动态再结晶行为的底层数据。基于d#/dε-#曲线,识别了真应力-应变曲线上能表征动态再结晶演变过程的特征点：临界应变εc,峰值应变εp及最大软化速率应变ε＊。引入表征晶体动力学的双曲正弦模型,通过线性回归求解得到动态再结晶激活能Q,建立流变应力本构方程。设计无量纲参数Z/A,对已修正的Avrami方程作线性回归分析,表征了不同变形条件对挤压态42CrMo钢动态再结晶体积分数演变的影响,并详细描述了动态结晶对应力软化的影响。结果表明：在高应变速率下,发生剧烈的软化后趋于稳定;在低应变速率条件下,出现硬化和软化的周期性循环。
Based on the actual stress-strain curves obtained in isothermal compression experiments which were performed at different temperatures and strain rates,the dynamic recrystallization(DRX) behavior of as-extruded 42CrMo high-strength steel was studied.From the dσ/d ε-σ curves,the characteristic points including the critical strain for DRX initiation(εc),the strain for peak stress(εp),and the strain for maximum softening rate(ε*) were identified to express the evolution of DRX.By regression analysis for conventional hyperbolic sine equation,the activation energy Q was determined,and the flow stress constitutive equation was established.The regression analysis for a modified Avrami type equation by a dimensionless parameter Z/A was designed.The influence of deformation conditions on the evolution of DRX volume fraction was described in detail.The study of the effects of DRX on stress softening shows that at high strain rate,the stress is dramatic softening and steady,while at low strain rate,there is a cycle of hardening and softening.
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