The laser-metal inert gas composite welding test of aluminum alloy bottom plate profile of high-speed train was carried out,and the hardness,morphology,mechanical property and microstructure of the welded joint ware analyzed.The result shows that the internal fusion of the welded joint is good,there is no porosity defect,and the shape of the weld is narrow and long,with a wide upper and narrow lower morphology.The average tensile strength of the welded joint is 230 MPa,which reaches 73.5％of the strength of the base metal,and the tensile fracture is in the heat-affected zone.The weld and the heat-affected zone softening zone are the weak points of the welded joint.Under the action of laser welding,the weld structure is equiaxed and columnar,and the structure is evenly distributed and fine.
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