Research on the "∞"-shaped laser scanning welding process for aluminum alloy

To solve the problems of poor quality and insufficient joint strength of aluminum alloy weld, a laser scanning welding test platform for aluminum alloy was built. Taking the butt welding of 5052 aluminum alloy with 5 nun and 3 mm thick specimens as the research objects, the study of a "infinity"-shaped laser scanning welding process was conducted, and the similarities and differences between the welding process and that of single pass laser welding were compared. The influence of "infinity"-shaped laser scanning welding parameters on the weld formation was investigated by the factor variable method. The change of the surface morphology and dynamic evolution of the molten pool was observed by a high-speed camera system. The optimal combination of the welding parameters was obtained by an orthogonal test. The research showed that the "infinity"-shaped laser scanning welding pool had good stability and a good weld quality. Under suitable welding parameters, the length and width of the molten pool could be increased significantly compared with those of the single pass laser welding. The growth rate of the length and width could reach 110.19% and 57.69%, respectively. The surface of the weld was evenly distributed with dense fish scales, and the porosity was less than 1%. The tensile strength of the specimen could reach 205.242 MPa, which was 93% that of the base metal; the topography of fracture was full of dimples, and the metallographic structure of the weld was fine and distributed with equiaxed dendrites.