AZ31镁合金板材弯曲行为的研究

Bending Behavior of AZ31 Magnesium Alloy Plate

对AZ31镁合金轧制过后的中厚板进行弯曲行为研究,以探究温度对镁合金板材的弯曲的影响以及弯曲过程中镁合金板材组织变化。结果发现,弯曲断裂应力随温度升高而大幅下降,其主要原因是温度升高导致非基面滑移和孪生被激活使得板材的变形抗力下降。通过模拟弯曲过程得到镁板内侧主要受压应力,外侧主要受拉应力,实际卷取过程中断裂应变大于弯曲断裂应变。在100℃弯曲过程中镁板的拉伸区产生孪晶数量远少于压缩区,拉伸区再结晶晶粒占比为2.10%,变形晶粒占比高,大部分晶界为小角度晶界,位错密度大,(0001)极密度点在轧制接触面法向(ND)方向聚集,晶粒c轴取向向ND方向转动,导致拉伸区变形程度大、协调性差,更易发生断裂。

The bending behavior of medium and thick plates after magnesium alloy rolling was analyzed.The influence of temperature on the bending of magnesium alloy plate and the microstructure evolution of magnesium alloy plate during bending were explored.The results reveal that bending fracture stress is decreased greatly with increasing in tem perature,which is attributed to the increase of temperature leading to the activiation of non-primary sliding and twins to decrease the deformation resistance.Bending simulation shows that the inner side is subjected to pressing stress while outer side is subjected to tensile stress,and fracture strain is higher than bending fracture strain during rolling process.Twins in tensile zone is far less than that in compressive zone of the magnesium plate during bending at 100℃,and recrystallization grain is 2.10%in tensile zone with high fractions of deformed grain and major of lower angle boundary as well as high dislocation density.Density point of(0001)pole is concentrated in ND direction,and c axis is rotated to ND direction,resulting in the poor coordination and large deformation of tensile zone,tending to crack.