基于材料参数修正的6013铝合金热变形本构模型优化

摘要

In order to develop a precise constitutive model to describe the relationships among material thermodynamic parameters during hot deformation, the hot plane compression deformation behavior of 6013 aluminum alloy was investigated on Gleeble-3500 thermal­mechanical simulating tester in the temperature range from 340 to 500 ℃ and strain rate range from 0.001 to 10 s-1. The influences of material parameters on the accuracies of the power function (PF) and hyperbolic sine (HS) constitutive model (CM) were discussed. Additionally, the advantages of two kinds of optimized constitutive models were comparatively analyzed. The results show that the corrected value of temperature coefficient (b) has an obvious effect on the parameter (a) obtained by an inverse method, and directly impacts the accuracy of PFCM. It is indicated that the computational­workload can be reduced significantly with high accuracy, through modifying the material parameters of HSCM by power function instead of polynomial function. Under the deformation condition (ε&≥0.01 s-1), the developed method of PFCM has higher precision of prediction, and the average relative error is only 5.209%; on the contrary, the proposed method of HSCM has higher precision of prediction under the deformation condition (ε&≤0.01 s-1), and the average relative error is only 5.226%.%为建立精确描述材料变形时热力学参数间重要关系的数学模型，采用 Gleeble-3500热模拟机测试研究6013铝合金在温度为340~500℃、应变速率为0.001~10 s-1范围内的平面应变热压缩变形行为，讨论材料参数对幂函数(PF)和双曲正弦函数(HS)本构模型(CM)精度的影响，对比分析优化后两类本构模型各自的优势。结果表明：温度系数(b)的修正对反求参数(a)的优化效果显著，将直接影响 PFCM 的预测精度；通过指数函数替换多项式对HSCM参数进行修正，可在保证预测精度的同时大幅减少计算工作量；PFCM在ε&≥0.01 s-1时的预测精度较高，平均相对误差仅为5.209%；HSCM在ε&≤0.01 s-1时的预测精度较高，平均相对误差仅为5.226%。