(1. 湖南大学 材料科学与工程学院，长沙 410082；2. 湖南大学 汽车车身先进设计制造国家重点实验室，长沙 410082)
摘 要: 在应变速率为0.01~50 s−1、温度为300~450 ℃的条件下，在Gleeble−3500热模拟机上对AZ80镁合金的高温热压缩变形特性进行研究。实验得出变形过程中的真应力应变曲线，并利用本构方程对流变应力值进行修正，进而利用修正后的应力值得出本实验本构方程中的系列常量；实验还分析温度、应变速率及应变量对微观组织的影响。结果表明：变形过程中的应力值随温度的升高而降低，随应变速率的升高而升高，且修正后的应力值高于未修正值；变形过程中发生动态再结晶且晶粒平均尺寸随变形参数的不同而改变，其自然对数随Zener-Hollomon(Z)参数的自然对数的升高呈线性降低。
关键字: AZ80镁合金；热变形；流变应力；本构方程
（1. College of Materials Science and Engineering, Hunan University,Changsha 410082, China;2. State Key Laboratory of Advanced Design and Manufacture for Vehicle Body,Hunan University, Changsha 410082, China）
Abstract:Hot compression tests of AZ80 magnesium alloy were performed on Gleeble-3500 at strain rates ranged in 0.01−50 s−1 and deformation temperature ranged in 300−350 ℃. The true stress/true strain curves were obtained in the tests. The flow stress was corrected by the constitutive equations and the constants in the constitutive equations were calculated using the corrected stress. The relation between stress and strain is obviously affected by strain rate and deformation temperature. The results show that the flow stress increases with the increase of strain rate at constant temperature, and decreases with the increase of deformation temperature at constant strain rate. The corrected flow stress is generally higher than the uncorrected value. The dynamic recrystallization takes place during the deformation process, and the average dynamically recrystallized grain size changes with deformation variables. A linear relationship between ln Z and ln dr is obtained (Z is Zener-Hollomon parameter and dr is average grain size
Key words: AZ80 magnesium alloy; hot compression deformation; flow stress; constitutive equation
