Mg-6Gd-1.2Y-0.53Zr合金的热变形行为及热加工图

采用热模拟试验法研究了变形温度(340～500℃)和应变速率(0.01～25 s^-1)对均匀化态Mg-6Gd-1.2Y-0.53Zr合金动态再结晶(DRX)临界应变及体积分数的影响，通过构建热加工图优化了其热加工工艺参数范围。结果表明，在0.01～1 s^-1的低应变速率下，该合金的动态再结晶(DRX)临界应变量随变形温度的升高而升高，而在10～25 s^-1高应变速率下，DRX临界应变量随变形温度的升高而略微下降。应变速率及变形温度的升高都使DRX体积分数增大，在500℃、25 s^-1条件下，合金的动态再结晶体积分数最高，达90.0%。根据构建的热加工图，当变形量在30%～80%之间时，较佳的热加工工艺区间为400～500℃、0.01～1 s^-1以及420～500℃、10～25 s^-1。在10～25 s^-1应变速率下，当变形量为10%～80%时，合金最适宜的变形温度为460～500℃。

Hot deformation behavior and processing map of Mg-6Gd-1.2Y-0.53Zr alloy

Influence of deformation temperature (340-500 ℃) and strain rate (0.01-25 s^-1) on critical strain and volume fraction of dynamic recrystallization (DRX) of homogenized Mg-6Gd-1.2Y-0.53Zr alloy was studied by thermal simulation test. The range of hot processing parameters was optimized by constructing processing maps. The results show that the DRX critical strain increases with the increase of deformation temperature in the low strain-rate range of 0.01-1 s^-1, while it decreases slightly with the increase of deformation temperature in the high strain-rate range of 10-25 s^-1. The volume fraction of DRX increases with the increase of strain rate and deformation temperature. The dynamic recrystallization volume fraction is the highest and reaches 90.0% at 500 ℃, 25 s^-1. According to the constructed processing map, when the deformation is 30%-80%, the better hot processing range is 400-500 ℃, 0.01-1 s^-1 and 420-500 ℃, 10-25 s^-1. At the strain rate of 10-25 s^-1, when the deformation amount is 10%-80%, the most appropriate deformation temperature of the alloy is 460-500 ℃.