两种唯象型本构方程描述AZ80镁合金高温流动应力的比较研究

A comparative study of two phenomenological constitutive equations to describe high temperature flow stress of AZ80 magnesium alloy

基于铸态AZ80镁合金热压缩实验数据,建立了两种唯象型本构方程(应变补偿的Arrhenius模型和动态回复(DRV)+动态再结晶(DRX)的两阶段模型)来描述AZ80镁合金在变形温度523~673 K和应变速率0.001~1 s^-1下的热变形行为。模型材料参数由线性拟合方法确定,对模型拟合精度进行定量分析表明:应变补偿的Arrhenius方程对流动应力的预测效果较好,相关系数R和平均相对绝对误差AARE的计算值分别为0.9930和5.26%;DRV+DRX两阶段本构方程预测结果相对较差,其R值和AARE值分别为0.9916和6.62%。比较分析表明,应变补偿的Arrhenius方程具有良好的适应性,可以在较大的温度和应变速率范围内准确预测不同变形条件下的流动应力曲线,工程适用范围广;DRV+DRX两阶段本构模型具有一定的物理意义,但是不能够很好地预测稳态流动应力,因而预测精度略低。

Based on the thermal compression test data of as-cast AZ80 magnesium alloy,two phenomenological constitutive equations(strain-compensated Arrhenius model and dynamic recovery(DRV)+dynamic recrystallization(DRX)two-stage model)were established to describe the thermal deformation behavior of AZ80 magnesium alloy at deformation temperature of 523-673 K and strain rate of0.001-1 s^-1.The material parameters of model were determined by the linear fitting method.The quantitative analysis of the model fitting accuracy shows that the strain-compensated Arrhenius equation has a good predictive effect on the flow stress.The calculated values of correlation coefficient R and average relative absolute error AARE are 0.9930 and 5.26%,respectively;the two-stage constitutive equation of DRV+DRX is relatively poor,and its R and AARE values are 0.9916 and 6.62%,respectively.The comparative analysis shows that the strain-compensated Arrhenius equation has good adaptability.It can accurately predict the flow stress curve under different deformation conditions in a wide range of temperature and strain rate and its engineering application range is wide.The DRV+DRX twostage constitutive model has clear physical meaning,but the prediction accuracy is slightly lower because the model cannot predict the steady state flow stress.