等通道角挤压AZ91D镁合金热压缩变形行为  

Elevated Temperature Compression Deformation Behavior of AZ91D Magnesium Alloy Processed by Equal Channel Angular Extrusion

作　　者：张继豪[1] 吴洋[2] 万元元[2] 柴舒心[2] 屈俊岑 

机构地区：[1]北京理工大学机电学院,北京100081 [2]西南技术工程研究所,重庆400039

出　　处：《精密成形工程》2017年第5期177-181,共5页Journal of Netshape Forming Engineering

摘　　要：在应变速率为0.005~1 s^(-1)、温度200~275℃条件下,利用Instron-5500热模拟机,对经过等通道角挤压(Equal Channel Angular Extrusion,ECAE)后的AZ91D镁合金的高温压缩特性进行了研究,得到了ECAE-ed态AZ91D镁合金真实应力-应变曲线,分析了挤压温度、应变速率等对其的影响,得出本构方程的一系列常量,建立了ECAE-ed态AZ91D镁合金在高温压缩中的本构方程关系式,并与铸态AZ91D镁合金进行了对比。结果表明:热压缩过程中,ECAE-ed态AZ91D镁合金与铸态一样,流动应力随温度的升高而降低,随应变速率的升高而升高;流动应力也可以用双曲正弦函数来描述,且双曲正弦值随Zener-Hollomon参数的自然对数的升高呈线性升高;两者同为正应变速率敏感材料,但ECAE-ed态AZ91D镁合金要比铸态应变速率敏感性小,其指数从铸态的m=0.14下降为0.096,变形激活能从182.65 kJ/mol上升为227.14 kJ/mol。研究结果对AZ91D镁合金进一步塑性成形和应用具有指导意义。Elevated temperature compression tests of AZ91D magnesium alloy were carried out on Instron-5500 at strain rates ranged from 0.005 s^（-1） to 1 s^（-1） and deformation temperature between 200℃ and 275℃. The true stress-strain curves were obtained and the influences of deformation temperature and strain rate on it were analyzed. Some constants of constitutive equation were gained and relations of constitutive equations of ECAE-ed AZ91D magnesium alloy in elevated temperature compression were established. At the same time, the results of ECAE-ed AZ91D were compared with that of cast. There were same processing between ECAE-ed AZ91D and cast： the lower the deformation temperature was, the higher the flow stress of AZ91D magnesium alloy would be; and the lower the strain rates was, the lower the flow stress would be. The flow stress could also be described with the hyperbolic sine function, and the hyperbolic sine value of flow stress increased linearly with the natural logarithm of Zener-Hollomon parameter. Both ECAE-ed and cast AZ91D are positive strain rate sensitivity materials, although the strain rate sensibility of AZ91D magnesium alloy in ECAE-ed was smaller than that of cast and the indexes reduced from 0.14 of cast to 0.096 of ECAE-ed. The value of deformation activated energy increased from 182.65 kJ/mol to 227.14 kJ/mol. The results have a guiding meaning for the further plastic deformation and industrial application of magnesium alloy.

关 键 词：AZ91D镁合金 高温压缩 流变应力 等通道角挤压 本构方程. 

分 类 号：TG146.2[一般工业技术—材料科学与工程]