采用Gleeble-1500热模拟试验机进行压缩实验,研究了ZK60镁合金在变形温度为473～723K、应变速率为0.001～1s~(-1)范围内变形过程中的组织演变.分析了变形程度、变形温度、变形速率对其动态再结晶行为的影响,探讨了其动态再结晶的形核机制.结果表明:ZK60合金高温塑性变形时的主要软化机制为动态再结晶,变形温度623K,应变量超过0.24时,在原晶界处出现大量的动态再结晶晶粒,并形成易延展的剪切区.变形温度是影响ZK60合金动态再结晶晶粒尺寸的主要因素,变形温度高于623K时,动态再结晶晶粒超过25μm.ZK60合金动态再结晶晶核在晶界弓弯处形成,随着应变量增加,出现亚晶界合并长大,长条状亚晶快速长大以及在剪切带变形区形核等.
The mtcrostructure evolution of ZK60 magnesium alloy was investigated by hot compressive tests on Gleeble-1500 thermal simulation test machine in temperatures range from 473K to 723K and strain rates of 0. 001-1s~(-1). The effect of deformed degree, temperature and rate on the behavior of dy-namic recrystallization was analyzed. The mechanism of dynamic recrystallization nucleation was dis-cussed. The result shows that dynamic recrtystallization is the mainly softened mechanism when ZK60 Mg alloy was deformed at high temperature. Many dynamic recrystallization grains that formed easy ductile shear zone were observed on the grain boundaries when ε>0.24 and T=623K. The deformed temperature has an important effect on the grain size of ZK60 Mg alloy dynamic recrystallization. The grain size of dynamic recrystallization is larger than 25μm at T>623K. The dynamic crystallization nucleus of ZK60 Mg alloy form on the grain boundaries arched zone. The combination and growth of subgrain occurred with strain capacity increasing. The long banding subgrains quickly grow and nucle-ate on the shear zone.
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