Al-Zn-Mg-Sc-Zr合金的热变形行为及加工图

Hot deformation behavior and processing map of Al-Zn-Mg-Sc-Zr alloy

在Gleeble-1500热模拟试验机上对Al-5.5Zn-1.5Mg-0.2Sc-0.1Zr铝合金进行高温等温压缩实验,研究该合金在变形温度为300-500℃、应变速率为0.01-10 s-1条件下的流变行为,建立合金高温变形的本构方程和加工图,采用电子背散射衍射（EBSD）分析变形过程中合金的组织特征。结果表明：流变应力随变形温度的升高而降低;当应变速率ε=10 s-1,变形温度为300-500℃时,合金发生了动态再结晶。Al-5.5Zn-1.5Mg-0.2Sc-0.1Zr合金的高温流变行为可用Zener-Hollomon参数描述。在热变形过程中,随着真应变增加,合金的变形失稳区域增大。该合金适宜的变形条件如下：变形温度300-360℃、应变速率0.01-0.32 s-1,或变形温度380-500℃、应变速率0.56-10 s-1。

The flow stress features of Al-5.5Zn-1.5Mg-0.2Sc-0.1Zr aluminum alloy were studied by the isothermal compression of cylindrical specimen in the temperature range of 300-500 ℃ and strain rate range of 0.01-10 s-1 with Gleeble-1500 simulated machine.The high temperature deformation constitutive equations and processing map were established,furthermore,the microstructure characteristics were studied by electron back-scattered diffraction（EBSD） analysis.The results show that the flow stress decreases with increasing deformation temperature.The dynamic recrystallization occurs at the strain rate of 10 s-1 and in the temperature range of 300-500 ℃.The flow stress of Al-5.5Zn-1.5Mg-0.2Sc-0.1Zr alloy during high temperature deformation can be represented by Zener-Hollomon parameter.In the hot deformation process,the flow instability zone increases with increasing the true strain.The feasible deformation temperature and strain rate are 300 ℃t360 ℃ and 0.01 s-1 0.32 s-1 or 380 ℃t500 ℃ and 0.56 s-1 10 s-1.