强冷条件下铝合金的变形行为

Deformation behavior of aluminum alloy under strong cooling

通过热模拟实验研究了铝合金在强冷条件下的变形行为和显微组织。结果表明,所得到的铝合金组织主要是树枝晶。树枝晶组织的凝固过程对外力施加的应变速率很敏感,ε·=0.10s-1是变形与凝固过程开始发生耦合作用的临界点。低于此值,变形对凝固过程无影响;高于此值时,变形作用于凝固过程,枝晶发生弯曲或断裂,凝固组织发生改变。随变形速率的增大,合金组织由枝晶密排的变形组织向破碎的枝晶组织转化,枝晶发生球化。应变速率越大,变形抗力越小,晶粒越细小,晶粒的球化特征越明显。

The deformation behavior and microstructure of Al alloy under strong cooling were investigated through thermal simulation. The results show that the microstructure of Al alloy solidified under strong cooling is mainly composed of dendrite structure. At a constant strain rate of ε·=0.117 s-1, no coupling process involving solidification and deformation occurs, and the microstructure belongs to deformed dendrite structure after solidification. The morphology of the dendrite structure is strongly sensitive to the strain rate. The coupling process of solidification and deformation occurs at a critical point when ε·=0.10 s-1. Above this point, the dendrite structure bends and fractures when solidifying. With the strain rate increasing, the alloy microstructure transforms from closelypacked and wellorganized dendrites to disintegrated and spheroidized dendrites. The larger the strain rate, the lower the deformation stress, and the finer the microstructure.