AZ81-1Y镁合金热加工行为和本构方程构建

Hot working behavior and constitutive equation construction of AZ81-1Y magnesium alloy

在变形温度为250~400℃,应变速率为0.003~1 s^(-1)的条件下,采用热模拟试验机对AZ81-1Y镁合金进行了热压缩实验,研究其热变形行为,分析了其微观组织演变规律及真应力-真应变曲线,并结合双曲正弦本构模型建立了其流变应力本构方程,并对流变应力本构方程进行了验证。结果表明:在一定的应变速率下,AZ81-1Y镁合金的流变应力随着变形温度的升高而降低;在同一变形温度下,流变应力随着应变速率的增大而增大;AZ81-1Y镁合金对温度及应变速率十分敏感,且有明显的再结晶现象;通过真应力-应变曲线得到AZ81-1Y镁合金的双曲正弦本构方程,计算其热激活能为153.23 kJ/mol;通过本构方程计算出的峰值应力与实验值具有较好吻合性,平均相对误差最大仅为2.294%。

Under the conditions of deformation temperature of 250-400℃and strain rate of 0.003-1 s^(-1),the thermal compression experiment of AZ81-1Y magnesium alloy was carried out by using a thermal simulation test machine,and its hot deformation behavior was studied.The microstructure evolution law and true stress-strain curve of the alloy were analyzed,the flow stress constitutive equation was established combined with the hyperbolic sinusoidal constitutive model,and the flow stress constitutive equation was verified.The results show that the flow stress of the AZ81-1Y magnesium alloy decreases with the increase of deformation temperature at a certain strain rate.At the same deformation temperature,the flow stress increases with the increase of strain rate.The AZ81-1Y magnesium alloy is very sensitive to temperature and strain rate,and has obvious recrystallization phenomenon.The hyperbolic sinusoidal constitutive equation of the AZ81-1Y magnesium alloy is obtained from the true stress-strain curves,and its thermal activation energy is 153.23 kJ/mol.The peak stress calculated by the constitutive equation is in good agreement with the experimental value,and the maximum average relative error is only 2.294%.