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在Gleeble-3500热模拟试验机上进行了挤压态Al-12Zn-2.4Mg-1.2Cu合金的等温压缩试验,获得了温度523~723 K、真应变0.1~0.6和应变速率0.001,0.01,0.1和1 s-1下的应力应变试验数据。基于Arrhenius本构模型,采用了含有Zener-Holloman参数的幂指数方程来描述温度和应变速率对流变行为的影响。采用线性回归分析的方法,研究了不同温度和应变速率下,材料常数随应变的变化规律。结果表明:除加工硬化率n外,其他材料常数Q,α,β和ln A3的数值均随着应变数值的增大而呈现出增大趋势;同时拟合出不同试验条件下不同材料常数的应变补偿方程,并借助于调整判定系数进行了应变补偿材料常数方程的拟合优度分析,在此基础上建立了试验合金的应变补偿本构模型。通过对比,分析了不同试验条件下的真实应力-应变曲线和建立模型的预测应力-应变曲线,并以相关系数R和平均绝对误差(AARE)为评价因子研究了考虑应变补偿Arrhenius本构模型的可靠性和适宜性,预测结果与试验结果相比较的R和AARE数值分别为0.995 82和6.66%,表明该模型精度高,可靠性好。
The isothermal compression tests of the extruded Al-12Zn-2.4Mg-1.2Cu alloy were carried out on a Gleeble-3500 thermal simulator. The results obtained were as follows: temperature 523-723 K, true strain 0.1-0.6 and strain rate 0.001, 0.01, 0.1 and 1 s-1 under the stress and strain test data. Based on the Arrhenius constitutive model, the power exponent equation with the Zener-Holloman parameter is used to describe the effect of temperature and strain rate on the rheological behavior. The linear regression analysis method was used to study the variation of material constants with strain at different temperatures and strain rates. The results show that the numerical values of Q, α, β and ln A3 of all other materials except for the work hardening rate n increase with the increase of the strain value. At the same time, the different material constants under different test conditions Strain compensation equation, and by means of adjusting the coefficient of determination, the goodness of fit of the constant strain compensation material equation is analyzed. Based on this, the strain compensation constitutive model of the test alloy is established. By comparison, the real stress-strain curve under different test conditions and the predicted stress-strain curve of the model are analyzed. The correlation coefficient R and the average absolute error (AARE) are taken as the evaluation factors to study the effect of Arrhenius constitutive model Reliability and suitability. The R and AARE values of the predicted result and the experimental result are 0.995 82 and 6.66% respectively, which shows that the model has high precision and good reliability.