加工参数对铸态AZ31B镁合金热变形行为及组织演变的影响

Effects of processing parameters on hot deformation behavior and microstructure revolution of as-cast AZ31B magnesiumSalloy

摘要:

本文借助热压缩实验研究了变形温度、应变速率和变形量对铸态AZ31B镁合金热变形行为及组织演变的影响规律。结果表明：(1) 峰值应力随着应变速率的降低和温度的升高而减小,主要的形核机制为晶界弓出形核、亚晶旋转形核、孪生诱发形核,以及连续再结晶；(2) 低于400℃变形时,温度的升高有利于再结晶的发生及晶粒细化；高于400℃时,晶粒尺寸开始迅速增大；(3) 在小于等于400℃变形时,低速率0.1s_-1更有利于再结晶晶粒细化；当变形温度高于400℃时,中速率1s_-1更有利于再结晶晶粒细化；(4) 高温低速率变形时,变形量主要影响的是晶粒尺寸的大小,而高温高速率变形时,变形量主要影响的是动态再结晶程度的大小。

Abstract:

In this paper, the effects of deformation temperature, strain rate and height reduction on hot deformation behavior and microstructure revolution of as-cast AZ31B magnesiumSalloy were researched in terms of hot compression tests. The results show that the peak stress decreases with the decreasing strain rate and increasing deformation temperature, and the main nucleation mechanism consists of initial grain boundary bulging nucleation, sub-grain rotation nucleation, twinning induced nucleation as well as continuous recrystallization. Moreover, the deformation temperature is below 400_oC, the increase of temperature will beneficial to recrystallization and grain refinement, while as above 400_oC, grain sizeSincreases rapidly. Furthermore, the deformation temperature is equal or lesser than 400_oC, the lower strain rate of 0.1s_-1 is more beneficial to the recrystallized grain refinement, while above 400_oC, medium strain rate of 1s_-1 is more advantageous. In addition, it is found that at higher temperature and lower strain rate, height reduction primarily affects the grain size, and at higher temperature and higher strain rate, height reduction primarily affects the dynamic recrystallization degree.