搅拌摩擦加工AZ31细晶镁合金超塑性行为研究

Superplasticity of Fine-grained AZ31 Magnesium Alloy Prepared by Friction Stir Processing

摘要:

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0.94μm~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。

Abstract:

Using friction stir processing to produce fine-grained microstructure in AZ31 magnesium alloy. The superplasticity of base metal and fine-grained AZ31 magnesium alloy with different grain sizes were compared. The results show that microstructure of the AZ31 hot-rolled plate with an average grain size of 7.67μm is refined to 0.94μm~3.21μm. The maximum elongation of the BM is 630% at 450℃ and 5×10-4/s-1, The maximum elongation of the FSP AZ31 alloy is 405% in the same situation. Grain size have no linear relationship with superplastic performance. Superplastic deformation mechanism is mainly based on grain boundary sliding. Twin crystal also affects the deformation. The failure mechanism is cavity generation, growth and coalescence.