铸态ZK60-1.0Er镁合金的热压缩变形行为

Hot Compression Deformation Behavior of As-cast ZK60-1.0Er Magnesium Alloy

采用Gleeble 1500D热模拟试验机对ZK60-1.0Er镁合金的热压缩变形行为进行了研究。热压缩参数应变速率?为0.0001,0.001,0.01和1.0 s^(-1);变形温度T为160,260,320和420℃。结果表明:ZK60-1.0Er镁合金的热压缩变形过程主要为动态回复DR和动态再结晶DRX。通过Zener-Hollomon参数建立了ZK60-1.0Er镁合金热压缩本构方程,根据本构方程计算的理论应力值与实际应力值吻合;同时还根据材料动态模型建立了该种合金的热加工图,并且通过对微观组织的观察和分析可知:该种镁合金的热加工图包含低温高应变速率和高温低应变速率2个失稳区域。该种镁合金适宜的热加工区间为:225~420℃,0.01~1.0 s^(-1),在该区域内存在1个功率耗散效率的峰值,η_(max)=45%。稀土相的存在促进了ZK60-1.0Er镁合金的动态再结晶形核,平均变形激活能Q=152.5 k J/mol,该合金的微观变形机制为晶界滑移和晶格自扩散导致的动态回复和动态再结晶。

Hot compressive deformation behavior of as-cast ZK60-1.0Er magnesium alloy with homogenization was studied by Gleeble-1500D thermal simulator at the strain rate of 0.0001, 0.001, 0.01 and 1.0 s^（-1）, the temperature of 160, 260, 320 and 420 °C. The results show that dynamic recovery and dynamic recrystallization are important processes of hot compression deformation of as-cast ZK60-1.0Er magnesium alloy. Constitutive equation of thermal compression of ZK60-1.0Er magnesium alloy was developed by the Zener-Hollomon parameter. Theoretical stress value which was calculated according to the constitutive equation is in accordance with the actual stress value. Meanwhile according to the material dynamic model, the processing map of this magnesium alloy was obtained. In addition, metallographic microstructure analysis shows that the processing map contains two instability areas： low temperature high strain rate and high temperature low strain rate. The optimal hot working range for this kind of alloy is 225~420 °C, 0.01~1.0 s^（-1）, and there is one peak efficiency η_（max）= 45%. The existence of rare earth promotes dynamic recrystallization nucleation（DRX） of ZK60-1.0Er magnesium alloy, the average deformation activation energy Q is 152.5 kJ/mol, and the main mechanisms are dynamic recovery and dynamic recrystallization caused by the grain boundary sliding and lattice self-diffusion.