基于Z参数金属热变形分段流变应力模型研究

考虑峰值应力后的稳态应力的软化机制,构建了包括动态回复和动态再结晶过程的基于Z参数的金属热成形分段流变应力数学模型,在Gleeble-3500热力模拟试验机上采用圆柱试样对金属材料进行了进行恒温和恒速热压缩变形试验,研究其在高温塑性变形过程中流变应力的变化规律,确定其形变表观激活能Q和应变硬化指数n,得到了峰值应力,峰值应变,稳态应力与lnZ的线性关系以及动态回复参数和动态再结晶动力学的数学模型,分段流变应力模型的模拟结果与试验结果吻合较好.

Investigation on Segmented Model of Flow Stress During Hot Deformation of Metal Based on Z Parameter

Considering the softening mechanism of steady state stress after peak stress, segmented model of flow stress for metal hot forming including dynamic recovery and dynamic recrystallization process was established based on Z parameter. The flow stress behaviors of cylindrical samples were investigated in the temperature range of 950-1100?? and strain rate of 0. 01-0. 5s-1 on Gleeble-3500 thermo-simulation machine. The strain hardening exponent and deformation activation energy were evaluated by linear regression analysis. The peak stress/strain and steady stress were all in linear ralationship with lnZ. In addition, dynamic recovery parameter and dynamic recrystalliazation kinetics were formulated. The flow stress constitutive equation of steel during hot compression was obtained taking the dynamic recovery and dynamic recrystalliazation into account. The results show that the dynamic recover and dynamic recrystallization occur obviously during hot compression of the test steel. The flow stress of test steel predicted by the proposed models well agrees with experimental results.