Cu-Ag合金高温流变特性及其改进的本构模型

High temperature deformation properties and the modification of constitutive model of Cu-Ag alloy

摘要:

在变形温度为973～1123K和应变速率0.01～10s_-1条件下对Cu-6 wt.% Ag合金进行等温热压缩实验。利用实验所得流变应力—应变曲线,分析了高应变速率下Cu-6 wt.% Ag合金高温塑性变形时微观组织的演变行为；研究了高温塑性变形中材料的塑性变形机制；构建了一种简化的本构模型,并引入Arrhenius方程及Z参数对模型进行改进。研究结果表明：Cu-6 wt.% Ag合金在热塑性变形过程中发生了明显的动态回复和动态再结晶,在应变速率为0.1s_-1、1s_-1温度为1123K变形条件下发生孪生行为,造成流变应力突变而升高,出现应力谷值；经改进后的本构模型,集成了变形温度、变形速率及应变对流变特性的影响,预测精度高,更利于通过计算机语言写入有限元软件分析计算。

Abstract:

The hot deformation behavior of Cu-6 wt.% Ag alloy was described by hot compression tests in the temperature range of 973～1123K and stain rates of 0.01～10s_-1. The microstructure evolution of the alloy was investigated in this paper. The true stress-strain curves were studied to reveal the hot deformation mechanism of Cu-6 wt.% Ag alloy. A simple constitutive model was established. The Arrhenius equation and Z were quoted in this investigation to modified the model. The results show that the dynamic recovery, dynamic recrystallization occurred in Cu-6 wt.% Ag alloy during hot deformation. And twinning behavior was observed at the strain rates of 0.1s_-1 and 1s_-1 temperature of 1123K. This twining behavior result in sharp changing of flow stress. With the increase of flow stress, a valley of stress was observed directly. The modified model which integrated the influence of temperature, strain rates, strain on flow characteristic could predict the stress accurately and be compiled easily.