高应变率下AZ31镁合金焊接接头动态力学性能

Dynamic Mechanical Property of AZ31 Magnesium Alloy Welding Joint Under High Strain Rate

采用分离式Hopkinson压杆在应变速率为900-2500s^-1范围内对轧制态AZ31镁合金氩弧焊（TIG）和搅拌摩擦焊（FSW）焊接接头进行了高速冲击压缩实验,利用金相显微镜和扫描电子显微镜对压缩后的接头组织和断口进行了观察。结果表明：随着应变速率的增大,合金的真应力-应变曲线变化不大,说明AZ31镁合金两种焊接接头对应变速率的敏感性较小;在高应变速率下FSW焊接接头的强度及塑性均优于TIG焊接接头;两种接头在高应变速率下的断裂方式均为解理断裂,但相对于TIG焊接接头,FSW焊接接头更加平整光滑;两种接头的显微组织对应变率均不敏感,并且在高应变率压缩下的变形方式相同,主要为滑移。

The dynamic compression test was carried out for rolled AZ31 magnesium alloy welding joint of argon tungsten-arc welding （TIG） and friction stir welding （FSW） with the split Hopkinson pressure bar at the strain rates of 900-2500s^-1. The microstructure and fracture mechanism of the specimens were analyzed by scanning electron microscope （SEM） and optical microscope. The results show that with the increasing of the strain rate, the true stress-strain curves of AZ31 magnesium alloy welding joint have little change, implying the stress of AZ31 welding joints is not sensitive to the strain rate. The strength and plasticity of FSW joint are better than those of TIG joint under high strain rate. The fracture mode of AZ31 welding joints is cleavage under high strain rate, but compared to TIG joint, the FSW joint fracture is more smooth. The deformation microstructure analysis demon- strates that the microstructure is not sensitive to the strain rate, and the deformation mechanism of AZ31 welding joints is slipping under high stain rate compression.