7020铝合金搅拌摩擦焊与MIG焊接对比试验

Study on the FSW process of 7020 aluminum alloy comparing with the MIG welding

采用搅拌摩擦焊(FSW)和MIG焊对高速客车车体材料7020铝合金板进行焊接,分别测试焊接接头的拉伸和冲击性能,观察焊接接头的金相组织,并进行接头的硬度分布测试。结果表明,搅拌摩擦焊接头抗拉强度高达309 MPa,是母材的78%,与MIG焊接头相当。焊接接头软化状况比MIG焊程度弱。焊接接头各区组织的不均匀性造成了接头硬度分布不均匀和冲击韧性差异,焊核区为等轴晶粒是该区韧性比MIG焊焊缝高一倍的重要原因。

In this paper,7020 ＇aluminum alloy plates used in super-speed vehicle are jointed by friction stir welding（FSW） and MIG welding. The mechanical property of the joints is tested.The microstructure is observed.And the distribution of the hardness of the joints is tested too.The results show that the tensile strength of the FSW joint is 309 MPa which reaches the 78% strength of the base material which equals to the MIG joint.The level of softening of the MIG joint is more serious than that of FSW joint.The nonuniform of the microstructure conduces to the nonuniform distribution of the hardness.The highest tenacity of the FSW joint is in weld-core zone for the equal-axle grain which compares with the MIG joint.