(1. 河南科技大学材料科学与工程学院，洛阳 471023；
2. 河南科技大学有色金属共性技术河南省协同创新中心，洛阳 471023)
摘 要: 采用Gleeble-1500D型热/力模拟试验机在变形温度300~450 ℃、应变速率0.005~1 s-1条件下对AZ41M镁合金进行热模拟压缩试验。用计算加工硬化率的方法处理试验数据，再结合lnθ-ε曲线的拐点及–？(lnθ)/？ε-ε曲线最小值判据，建立合金热变形过程中的动态再结晶临界应变模型。根据热压缩实验数据，分析温度和应变速率等工艺参数对合金动态再结晶的影响。结果表明：在该实验条件下，AZ41M镁合金的lnθ-ε曲线均具有拐点特征，对应的-？(lnθ)/？ε-ε曲线均出现最小值，该最小值所对应的应变即为临界应变εc，得到合金临界应变预测模型；临界应变随变形温度的降低和应变速率的增加而增大，且峰值应变εp和临界应变εc的比值满足εp/εc = 1.97。
关键字: AZ41M镁合金；加工硬化率；动态再结晶；临界条件；组织演变
（1. School of Materials Science and Engineering,
Henan University of Science and Technology, Luoyang 471023, China;
2. Collaborative Innovation Center of Nonferrous Metals of Henan Province,
Henan University of Science and Technology, Luoyang 471023, China）
Abstract:The hot simulation compression tests of AZ41M magnesium alloy were conducted at deformation temperature in the range of 300-450 ℃ and strain rate in the range of 0.005-1 s-1 with the Gleeble-1500D thermal-mechanical simulation test machine. The critical strain model of dynamic recrystallization for AZ41M magnesium alloy during hot deformation was obtained by computing the work hardening rate θ from initial experimental data and combining with the inflection point criterion of lnθ-ε curves and the minimum value criterion of -？(lnθ)/？ε-ε curves. The influences of temperature and strain rate on the dynamic recrystallization were investigated based on the experimental data. The results show that an inflection point presents in the lnθ-ε curve and a minimum value appears in the corresponding –？(lnθ)/？ε-ε curve when the critical state of AZ41M magnesium alloy is attained, the strain that relates to the minimum value is the critical strain εc. The predicting model of critical strain is described. The critical strain increases with the decrease of deformation temperature and the increase of strain rate, and the ratio of peak strain (εp) and critical strain εc is 1.97.
Key words: AZ41M magnesium alloy; work hardening rate; dynamic recrystallization; critical condition; microstructure evolution
