AZ81E镁合金的高温流变应力模型及热加工图研究

在应变速率为0．003—3．0s^-1、温度为340～430℃的变形条件下，采用Gleeble-1500热模拟机对AZ81E镁合金进行高温热压缩变形特性研究。结果表明：流变应力随变形温度的升高和应变速率的降低而减小，峰值应力随温度的降低和应变速率的升高向应变较大处转移，进入稳态阶段的临界应变明显增大。结合Arrhenius方程并引入Zener-Hollomon参数，构建AZ81E镁合金的高温流变应力模型，其平均变形激活能为166．15kJ／mol。根据材料动态模型，计算并分析AZ81E镁合金的热加工图。利用热加工图确定热变形的流变失稳区，获得试验参数范围内的热变形过程最佳工艺参数：热加工温度范围为380～420℃，应变速率范围为0．01～0．03S^-1.

Research on the High Temperature Flow Stress Model and Processing Map of AZ81 E Magnesium Alloy

The isothermal compressive deformation characteristics of AZ81E magnesium alloy were researched by Gleeble-1500 thermal simulator at the strain rate of 0. 003 - 3.0 - 1, the temperature of 340 - 430 degrees Celsius. The simulation results show that the flow stress decreased with increase in deformation temperature and decrease in strain rate, the peak stress transfer to the greater strain area with the decrease in temperature and increase in strain rate. When entering the steady-state phase, the critical strain increased obviously. Combined with the Arrhenius equation and introduction of the Zener-Hollomon parameter, high temperature AZ81E magnesium alloy flow stress model was developed and the average deformation activation energy was 166. 15 kJ/mol. According to the material dynamic model, hot working diagram of the AZ81E magnesium alloy was calculated and analysised. The flowing thermal deformation of rheological instability region was determined by the hot working diagram and the optimum technological parameters of the hot thermal deformation process were proposed as follows： the hot processing temperature range,was 380 to 420 degrees Celsius, the strain rate range was 0. 01 to 0. 03 s^-1.