挤压态ZK61M镁合金热压缩变形行为与本构方程建立

Hot compression deformation behavior of extruded ZK61M magnesium alloy and establishment of constitutive equation

为研究挤压态ZK61M镁合金的热变形行为,采用Gleeble-3800热模拟机在温度为300～450℃、应变速率为0. 001～0. 5 s^(-1)的条件下进行热压缩实验,分析了变形温度、应变速率对流变应力的影响,并对铸态镁合金和挤压态镁合金的变形激活能进行了研究对比,最终将本构方程应用于模拟软件中进行量化验证。结果表明,该合金的流变应力与变形温度负相关,与应变速率正相关,应力-应变曲线拥有动态回复和再结晶的特点。Mg-Zn-Zr系变形镁合金相对类似成分的铸造镁合金,具有更低的变形激活能,如ZK61M,大约为120 kJ·mol^(-1),且Mg-Zn-Zr系镁合金成分是决定变形激活能大小的主要因素,成分相同时,材料的变形激活能基本相近,模拟曲线与实验曲线趋势具有一致性,应力峰值接近。通过Arrenhenius本构方程计算出挤压态ZK61M镁合金的变形激活能Q=122. 685 kJ·mol^(-1),应力指数n=4. 13652,为Mg-Zn-Zr系变形镁合金的热加工工艺参数和制备提供了理论指导。

In order to study the hot deformation behavior of extruded ZK61M magnesium alloy,the hot compression test under the condition of the temperature of 300-450℃and the strain rate of 0.001-0.5 s-1 was carried out by Gleeble-3800 thermal simulator,and the effects of deformation temperature and strain rate on the flow stress were analyzed.And the deformation activation energies of cast magnesium alloy and extruded magnesium alloy were studied and compared,and the constitutive equation was finally applied to the simulation software for quantitative validation.The results show that the flow stress of alloy is negatively correlated with the deformation temperature and positively correlated with the strain rate.The stress-strain curves are found to have the characteristics of dynamic recovery and recrystallization.Compared with the cast magnesium alloy of similar components,the deformation activation energy of Mg-Zn-Zr wrought magnesium alloy is lower,like ZK61M,it is about 120 kJ·mol-1.And for Mg-Zn-Zr magnesium alloys,the alloy composition is the main factor that determines the value of deformation activation energy,when the compositions are same,the deformation activation energies are basically similar.Both the simulated curve and the test curve have the same trend,and the peak stresses are closed.Applied by Arrenhenius equation,the deformation activation energy of extruded ZK61M magnesium alloy is Q=122.685 kJ·mol-1,and the stress exponent is n=4.13652,which provides theoretical guidance for the thermal processing parameters and preparation of Mg-Zn-Zr wrought magnesium alloy.