车身用新型Al-Zn-Mg铝合金热变形本构方程及热加工图

Hot deformation constitutive equation and hot processing map of novel Al-Zn-Mg aluminum alloy for automobile body

设计了一种汽车车身结构件用Al-Zn-Mg中强铝合金,利用Gleeble-3500热模拟试验机测试了该合金在不同热变形条件下的应力-应变曲线,构建了峰值应力本构方程,绘制了不同应变量下合金的热加工图。结果表明:Al-Zn-Mg铝合金热变形过程呈现正的应变速率敏感性和负的温度敏感性;建立的以Z参数表示的Arrhenius本构方程所预测的峰值应力与实验值平均相对误差为8.4%,线性相关系数为0.987,说明拟合情况良好;根据不同应变量下的热加工图,发现流变失稳区及功率耗散低谷区均集中在高温高应变速率区和低温低应变速率区,且随着应变量的增大均逐渐缩小,最佳热变形工艺参数范围为350~500℃,0.01~0.1 s^-1。

Al-Zn-Mg aluminum alloy with medium strength for auto body structural part was designed,and the Gleeble-3500 thermal simulator was used to test the stress-strain curves of the alloy under different hot deformation conditions. The peak stress constitutive equation was established and the hot processing maps under different strains were drawn. The results show that the hot deformation process of the Al-Zn-Mg aluminum alloy shows positive strain rate sensitivity and negative temperature sensitivity. The average relative error between the predicted peak stress value by the established Arrhenius constitutive equation represented with parameter Z and experimental value is8. 4%,and the linear relative coefficient is 0. 987,which indicates the fitting situation is good. The rheological instability zone and power dissipation trough zone were focused on the high temperature-high strain rate zone and low temperature-low strain rate zone according to the hot processing maps under different strains,and diminishes gradually with the increase of strain. The optimal range of hot deformation process parameters is 350-500 ℃,0. 01-0. 1 s^-1.