AZ80镁合金热变形过程中的动态再结晶动力学和运动学模型

Dynamics and kinematics model of dynamic Recrystallization during Thermal Deformation of AZ80 Magnesium alloy

摘要:

采用热模拟实验方法测试了AZ80镁合金材料的真实应力-应变曲线, 变形温度范围533K - 683K, 应变速率范围0.001 - 10 s-1, 变形程度为50%。动态再结晶的晶粒尺寸随着变形温度的升高和应变速率的降低而增大。确定了AZ80镁合金的热激活能, 确定了AZ80镁合金材料热变形时的本构方程。根据Sellars方程, 确定了AZ80镁合金的动力学模型, 其定义为描述发生动态再结晶体积分数与变形温度和应变速率的函数关系。确定了AZ80镁合金的运动学模型, 其定义为描述动态再结晶晶粒尺寸与Z函数之间数学关系. 动态再结晶晶粒尺寸的模型计算结果与实验结果相吻合，相对误差小于11.8%。确定了临界应变和稳态应变与Z函数之间数学关系。

Abstract:

Abstract: The stress-strain curves of AZ80 magnesium alloy are tested by thermal simulation experiment, which the deformation temperature is from 533K to 683K, and strain-rate is from 0.001 to 10 s-1, and deformation degree is 50％. The grain size of dynamic recrystallization (DRX) increases with rising of deformation temperature and reducing of strain-rate. According to the Arrhenius equation and experiment data, the energy of thermal activation of AZ80 magnesium alloy is determined, and a kind of constitutive equation of AZ80 magnesium alloy is established. According to the Sellars equation, the dynamics model of AZ80 magnesium alloy is established, which is defined as the relationship between the volume fraction of DRX and deformation temperature and strain-rate. The kinematics model of AZ80 magnesium alloy is established, which is defined as the relationship between grain size of DRX and deformation temperature and strain-rate. The calculated results of grain size of DRX are in agreement with that of experiment, and relative errors are less than 11.8%. The relationship model between critical strain and steady strain of DRX with deformation temperature and strain-rate are established.