轧制温度和后处理方式对AZ31镁合金显微组织和力学性能的影响

在不同的轧制温度下，对AZ31镁合金板进行轧制，然后取出轧板立即进行水冷、空冷和退火3种不同的后处理。探究轧制温度和后处理对镁合金显微组织和力学性能的影响。结果表明，轧制温度为250、300℃时，水冷和空冷处理后板材存在着大量的孪晶，350℃时由于轧制温度较高，孪晶的数量很少；水冷处理后的平均晶粒尺寸要小于空冷，空冷处理之后的孪晶数量略少于水冷，当轧制温度为350℃时，退火处理后，晶粒尺寸减小，晶粒趋于等轴状，晶格畸变程度低。在相同的轧制温度下，水冷处理的镁合金板材的屈服强度、抗拉强度和硬度较高；退火处理后可以显著提高板材的伸长率，但屈服强度、抗拉强度略有下降。轧制温度升高时，3种后处理方式之间屈服强度和抗拉强度的最大差值会减小。

Effect of rolling temperature and post-treatment on microstructure and mechanical properties of AZ31 magnesium alloy

AZ31 magnesium alloy plates were rolled at different temperatures, and the rolled plates were immediately subjected to different post-treatments (water cooling, air cooling and annealing). The effects of rolling temperature and post-treatment on microstructure and mechanical properties of the tested magnesium alloy were investigated. The results show that when rolled at 250 ℃ and 300 ℃, there are a lot of twins in the plates after water cooling and air cooling. When rolled at 350 ℃, the number of twins is small due to the higher rolling temperature, the average grain size after water cooling is smaller than that after air cooling, and the number of twins after air cooling is slightly smaller than that after water cooling. After annealing following the 350 ℃ rolling, the grains tend to be equiaxed and finer with low lattice distortion. At the same rolling temperature, the yield strength, tensile strength and hardness of the rolled alloy plate after water cooling are higher than that of other treatments. After annealing, the elongation of the plates can be significantly increased, but the yield strength and tensile strength are slightly decreased. When the rolling temperature increases, the maximum difference of yield strength and tensile strength between the three post-treatment methods decreases.