2024A铝合金高温流变行为及本构关系研究

采用Gleeble-3500热模拟试验机对2024A铝合金进行等温热轧,对其高温流变行为进行了研究。通过试验获得2024A铝合金在温度为300~450℃、应变速率为0.01~10s-1时的真应力-真应变曲线。结果表明,2024A铝合金的流变应力与温度、应变速率和变形量之间呈非线性关系,流变应力随着应变速率增大而升高,随着变形温度的升高而降低。基于试验数据,分别建立考虑应变补偿的Arrhenius和修正的Johnson-Cook(M-JC)本构模型,引入统计学方法对模型精度进行量化评估:Arrhenius模型的平均相对误差和均方根误差分别为5.02%和5.88MPa,M-JC模型的平均相对误差和均方根误差分别为3.72%和5.27MPa,可见M-JC模型预测精度优于Arrhenius模型,说明M-JC模型能更为准确地描述2024A铝合金的高温轧制过程中的流变行为。

Hot Deformation Behavior and Constitutive Equation of 2024A Aluminum Alloy

The high-temperature flow behavior of 2024 Aaluminum alloy was investigated by isothermal hot rolling tests with a Gleeble-3500 thermal simulator.The true stress-strain curves of 2024 Awere obtained by isothermal hot compression tests at the temperature of 300~450℃and the strain rate of 0.01~10 s-1.The results reveal that the flow stress of 2024 Ahas a nonlinear relationship with temperature,strain rate and strain,where it is increased with the increase of strain rate and decrease of deformation temperature.The modified Arrhenius constitutive equation considering the compensation of strain and modified Johnson-Cook(M-JC)model were established based on the experimental data,respectively.Then,the statistical method was introduced to quantitatively evaluate the accuracy of the two models.The average absolute relative error(AARE)and root mean square error(RMSE)of the modified Arrhenius model are 5.02%and 5.88 MPa,and the corresponding values of the M-JC model are 3.72%and 5.27 MPa,respectively.Therefore,the prediction accuracy of M-JC model is superior to that of the modified Arrhenius model,so it can be applied to describe hot flow behavior of 2024 Aaluminum alloy during rolling process.