挤压态镁合金动态再结晶临界模型

Critical model on dynamic recrystallization of as-extruded magnesium alloys

采用变形温度200~500℃,应变速率为0.005~5 s-1时在Gleeble1500热模拟试验机上对AZ31挤压态镁合金热变形行为进行试验研究。运用单参数法并引入温度补偿应变速率因子Z,构建挤压态镁合金动态再结晶临界表征模型,通过观察典型变形条件下微观组织的动态再结晶情况验证模型正确性。结果表明:发生动态再结晶所需的激活能为171.15 kJ/mol。此外,得到峰值应变与Z参数的定量关系。临界应变与临界应力随着温度升高和应变速率降低而减小,减小Z值可促进挤压态镁合金动态再结晶的发生。

The hot deformation behavior of AZ31 as-extruded magnesium alloy at 200~500℃and 0.005~5 s-1 was studied by Gleeble1500 thermal simulation machine.With single parameter method and temperature compensated strain rate factor Z,the critical characterization model of dynamic recrystallization of as-extruded magnesium alloy was constructed.The validity of the model was verified by observing the dynamic recrystallization of microstructure under typical deformation conditions.The activation energy required for dynamic recrystallization was 171.15 kJ/mol.In addition,the quantitative relationship between the peak strain and parameter Z was obtained.The critical strain and critical stress decreased with the increase of temperature and the decrease of strain rate,indicating that the smaller Z value could promote the dynamic recrystallization of as-extruded magnesium alloy.