软取向AZ80+0.4%Ce镁合金热拉伸变形行为研究

Hot tensile deformation behavior of soft-oriented AZ80+0.4%Ce magnesium alloys

借助万能材料试验机、光学显微镜和扫描电镜,研究软取向AZ80+0.4%Ce镁合金挤压板材在变形温度为300~420℃、应变速率为0.000 5~0.5 s-1条件下的热拉伸变形行为。结果表明:随温度的升高流变应力逐渐下降,晶体内孪晶逐渐消失,动态再结晶增强;随应变速率的增加流变应力增大,晶粒尺寸减小。由断口分析可知:随着温度的升高、应变速率的降低,韧窝数量逐渐变少且深度变得越来越深,合金表现出较好的塑性变形行为。根据Arrhenius本构关系模型,建立AZ80+0.4%Ce镁合金的流变应力本构模型,峰值应力的试验值与计算值的相对误差仅为5.793%。

The hot tensile deformation behavior of soft-oriented AZ80＋0.4%Ce magnesium alloy was investigated by means of universal testing machine,optical microscope and scanning electron microscope. The hot tensile deformation behavior of the alloy extruded sheet was studied at deformation temperature of 300-420 ℃ and strain rate of 0.000 5-0.5 s-1. The results show that the flow stress gradually decreases with the increase of temperature,the twins in the crystal gradually disappear,and the dynamic recrystallization increases. With the increase of strain rate,the flow stress increases and the grain size decreases. Based on the fracture analysis,it can be seen that as the temperature increases and the strain rate decreases,the number of dimples gradually decreases and the depth becomes deeper,and the alloy performs better in plastic deformation behavior. According to the Arrhenius constitutive model,the flow stress constitutive model of AZ80＋0.4%Ce magnesium alloy was established. The relative error between the experimental and calculated values of peak stress is only 5.793%.