Al-9.4Zn-1.9Mg-2.0Cu合金的热变形流变行为与本构方程

Flow behaviors and corresponding constitutive equation of the Al-9.4Zn-1.9Mg-2.0Cu alloy

摘要:

本文对Al-9.39Zn-1.92Mg-1.98Cu合金做等温热模拟压缩实验，变形温度为300 ℃~460 ℃，应变速率为0.001 s-1~10 s-1，变形量为60%。结果表明：变形时,合金的流变应力力随着变形温度的降低或应变速率的增大而增大。由于热变形时存在摩擦影响，对流变应力曲线进行修正.结果发现摩擦修正后的应力值低于实验值，摩擦力对流变应力的影响程度随着温度的降低和应变速率的增大而增大。基于经典的Arrhenius方程，考虑应变量对材料常数(α，n，Q和A)的影响，构建该合金在热变形时的本构方程。评价改进的本构方程预测能力发现流变应力值与实测值吻合度较高，其相关度高达93.5%。

Abstract:

Hot compression tests of the Al-9.39Zn-1.92Mg-1.98Cu alloy are carried out in the temperature range from 300 ?C to 460 ?C and the strain rate range from 0.001 s-1 to 1 s-1, and the height reduction degree is 70%. The flow stress is corrected because of the effect of friction. Results show the flow stress decreases with increasing the temperature increasing or decreasing the strain rate. The friction effect is more and more obvious when the temperature is low and the strain rate is high. A revised constitutive equation considering the influence of strain is established based on the Arrhenius-type model. Compared with the experimental and predicted flow stresses, the revised constitutive equation has a higher accuracy. Their correlation coefficient and average absolute relative error is 0.95 and 2.45%, respectively.