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借助搅拌摩擦加工工艺制备了AZ31细晶镁合金,研究对比了原始母材和各种晶粒尺寸细晶镁合金的超塑性行为。结果表明:AZ31板材平均晶粒尺寸由7.67μm细化到0.94~3.21μm。在450℃,应变速率5×10~(-4) s~(-1)时原始母材最大延伸率为630%,搅拌摩擦加工后的材料最大延伸率为405%,说明晶粒尺寸与超塑性性能没有线性关系。超塑性变形机制主要是晶界滑移,孪生对变形也有一定影响。断裂机制是晶间微小空洞的形成、长大和连接。
The AZ31 fine grain magnesium alloy was prepared by the friction stir process. The superplastic behavior of the original base metal and fine grain magnesium alloys with different grain sizes was compared. The results show that the average grain size of AZ31 plate is refined from 7.67μm to 0.94 ~ 3.21μm. The maximum elongation of the original base metal at 630 ℃ and strain rate of 5 × 10 ~ (-4) s ~ (-1) is 630%, and the maximum elongation of the material after the friction stir processing is 405% Plasticity has no linear relationship. Superplastic deformation mechanism is mainly grain boundary slip, the twin also have a certain impact on the deformation. Fracture mechanism is the formation of small intergranular cavity, growth and connection.