热轧工艺对AZ61镁合金铸轧板显微组织的影响

Microstructure Evolution of Hot Rolled AZ61 Magnesium Alloy Strip

通过研究不同温度下AZ61镁合金铸轧板坯的再加工性能,发现铸轧AZ61镁合金板坯在400、350℃时极限再加工变形量大于80%,而在300℃时减小到60%左右,在250℃时其极限再加工压下量下降到40%左右,200℃时进一步降低到20%～30%之间,在室温下极限压下量仅为10%左右。而从变形组织来看,在极限变形压下量范围内,冷轧微观组织与原始态的没有本质区别;200℃时轧制晶粒明显伸长,呈纤维状;在高于250℃轧制时,晶粒明显细化;在400℃轧制时,晶粒细化效果显著,晶粒平均尺寸达到5μm左右。

Effects of different temperature on re-deforming rate of cast-rolling AZ61 magnesium alloy strip were examined.The results reveal that the ultimate re-deforming rate of magnesium strip is more than 80% at 400℃ and 350℃,while it reaches 60% at 300℃ and it falls to about 40% at 250℃,furthermore,it drops down to 20%～30% at 200℃ and only 10% at room temperature.Deformed structure observation reveals that microstructure of cold rolled alloy is substantially similar to that of cast-rolling ones in range of ultimate re-deforming rate.Grain in rolled alloy at 200℃ exists in fibrous structure due to being elongated,and grain size can be evidently refined with rolling at more than 250℃.Grain with approximately 5μm in average size can be observed with rolling at 400℃.