AZ70镁合金热压缩变形特性

在温度为300℃～420℃、应变速率为0.001s-1～1s-1的变形条件下,采用Gleeble-1500热模拟机对AZ70镁合金热压缩变形特性进行了研究。结果表明,合金的流变应力随应变速率的增大而增大,随温度的升高而降低;在给定的变形条件下,计算出合金的变形激活能为132kJ/mol,应力指数为6.2;建立了合金高温变形的本构方程;降低变形温度和提高应变速率可使再结晶晶粒平均尺寸减小。根据实验分析得出,材料的最佳热加工工艺条件为变形温度340℃～400℃,应变速率0.001s-1～0.1s-1,并提出以低速为宜。

Hot compression deformation behavior of AZ70 magnesium alloy

Hot compression tests of AZ70 magnesium alloy were performed on Gleeble 1500 at deformation temperature ranged in 300℃~420℃ and strain rates 0.001s-1~1s-1.The results show that the relation between stress and strain is affected obviously by strain rate and deformation temperature.Flow stress becomes higher with increase of strain rate at constant temperature,and lowers with increase of deformation temperature at constant strain rate.The deformation activation energy 132kJ/mol and the corresponding stress exponent 6.2 were determined respec-tively.The constitutive equation was established at the elevated temperature.The average dynamically recrystallized grain size(drec)is decreased by the reduction of deformation temperature and the increase of strain rate.In the present work the good deformation condition is temperature of 340℃～400℃ with stain rate of 0.001s-1～0.1s-1 and the lower strain rate is preferred.