宽幅AZ31B铸轧镁合金温轧工艺条件的组织性能

Microstructure and mechanical properties of casting broadloom AZ31B magnesium alloy under warm rolling process conditions

在温度范围为300~450℃,压下率为20%~40%,轧制速度为0.1~0.8 m/s工艺条件下对宽幅AZ31B铸轧镁合金进行了多组温轧试验,而后对轧后的镁板分别进行室温拉伸,并用光学显微镜观察各条件轧制后的组织形态,用SEM观察拉伸试样断口形貌,同时进行往复摩擦实验。研究表明:轧制温度为350℃,轧制速度为0.1 m/s,压下率为30%时可以获得很好的断裂强度,在此温轧条件下镁合金板材的耐磨损系数增加了80%;温度为450℃,轧制速度为0.8 m/s,压下率为40%时可以获得很好的塑性变形能力;压下率超过30%之后,晶界处容易产生位错塞积,导致累积变形量增加及内应力激增,是镁合金边部产生微裂纹进而形成断裂失效的主要原因。

Warm rolling process for broadloom AZ31 B magnesium alloy casting plate was carried out under temperature range of 300-450 ℃,reduction rate of 20% to 40% and speed from 0. 1 m / s to 0. 8 m / s,and then the room temperature tensile experiment was taken. The microstructure morphology of the alloy was observed under different rolling conditions by optical microscope and the fracture morphology of tensile specimens was studied by SEM,while reciprocating friction experiments and corrosion experiments were tested. The results show that a better fracture strength can be obtained under rolling temperature of 350 ℃ and rolling speed of 0. 1 m / s,reduction rate of 30%. The wear resistance coefficient of the magnesium alloy sheet is improved by nearly 80% under the same warm rolling condition. A better plastic deformation can be obtained under rolling temperature of 450 ℃,rolling speed of 0. 8 m / s and reduction rate of 40%. After the reduction rate exceeded 30%,the grain boundary is easy to produce dislocation pile and result in increased accumulation surge in the amount of deformation and internal stress,this is the main reason for magnesium alloy edge micro-cracks and the formation of fracture failure.