7050铝合金修正本构模型及Zener-Hollomon参数演化

Modified constitutive model and Zener-Hollomon parameter evolution of 7050 aluminum alloy

依据等温热压缩结果,研究了均匀化7050铝合金在变形温度为300~450℃、应变速率为0.001~1 s^(-1)及应变量为0.9下的变形行为。提出了一种考虑变形条件与材料参数耦合关系的修正Arrhenius本构模型。结果表明,该修正本构模型的平均绝对百分比误差和均方根误差分别为2.093%和1.983 MPa,说明该修正本构模型的预测精度较高。此外,由修正模型计算得到的拓展值与实验获得的真应力-真应变曲线的变化规律一致,也证明了修正本构模型具有较好的精确度与扩展性。最后,根据修正本构模型计算了7050铝合金在不同变形条件下的变形激活能Q和Zener-Hollomon参数(Z参数),分析了Z参数对变形组织的影响,结果表明,ln Z随变形温度和应变速率的增加而降低,并且随着ln Z的降低,其变形微观组织形态由动态回复逐渐转变为动态再结晶。

Based on the isothermal thermal compression results,the deformation behavior of 7050 aluminum alloy at deformation temperature of 300-450℃,strain rate of 0.001-1 s^(-1) and strain of 0.9 was investigated.A modified Arrhenius constitutive model considering the deformation conditions and coupling relationship of material parameters was proposed.The results show that the mean absolute percentage error and the root mean square error of the modified constitutive model are 2.093%and 1.983 MPa,respectively,which shows that the prediction accuracy of the modified constitutive model is high.Furthermore,the expanded values calculated by the modified model is consistent with the changing law of true stress-true strain curves obtained by experiments,which also proves that the modified constitutive model has better accuracy and expansibility.Finally,the deformation activation energy Q and Zener-Hollomon parameter(Z parameter)of 7050 aluminum alloy under different deformation conditions were calculated by the modified constitutive model,and the effect of Z parameter on the deformation microstructure was analyzed.The results show that ln Z decreases with the increase of deformation temperature and strain rate.And with the decrease of ln Z,the deformation microstructure morphology gradually changes from dynamic recovery to dynamic recrystallization.