几种典型铝合金应变率敏感性及其塑性流动本构模型

Strain rate sensitivity and constitutive models of several typical aluminum alloys

建立了塑性流动本构模型，对A13003-H12、2219-T87、7050-T7451、2024-T351和LY12-cz 5种典型的铝合金在应变率从10^-4／s到8000／s，初始温度从77K到800K以及真实应变超过0．50条件下进行系统实验，并对塑性流动行为进行分析。结果表明：这些铝合金材料具有应变率效应；铝合金材料应变率敏感性可归于短程障碍对热激活位错运动的影响；在200～600K时，这些材料存在第三类动态应变时效现象。基于热激活位错运动机制，推出一个物理概念的本构模型，比较得出的模型预测结果和实验结果一致，可方便用于工程应用。

In order to evaluate the strain rate sensitivity and set up the constitutive model of aluminum alloys, five types of aluminum alloys as A13003-H 12, 2219-T87, 7050-T7451, 2024-T351 and LY12-cz were systematically tested under strain rate range of 10-4-8 000/s, initial temperature of 77-800 K and the true strain exceeding 0.50. The plastic flow behavior of these materials was also analyzed. The results show that the plastic flow stress of these aluminum alloys is really sensitive on the strain rates. The aluminum alloys have strain rate sensitivity due to a thermally-activated resistance effect of short-range barriers. The third kind of dynamic strain aging occurs at temperature of 200-600 K. Finally, based on the mechanism of dislocation motion, a physically based model is established. The theoretical predictions agree well with the experimental results, and it can be easily used in the engineering application.