Metal spattering in laser scanning welding of T2 copper and welding quality

Considering that copper laser welding tends to produce spattering with poor weld formation, and porosity defects, the single-mode fiber laser was employed to conduct conventional laser linear welding and scanning welding experiments on T2 copper in this study. Using high-speed photography and image processing technology, the metal spattering during welding was studied. Then, the effect of different welding paths on the stability of the laser welding copper process was investigated. Besides, the welding quality of the samples under different welding paths was compared and explored from the perspectives of surface morphology, internal porosity, microstructure, mechanical properties and electrical conductivity of the joints. The results show that: compared with the conventional laser linear welding, laser scanning welding of “O” shape, “8” shape and “∞” shape trajectories can extend the cycle variation of keyhole, reduce the metal vapor and intensity of plasma eruption, improve the welding process stability, and inhibit the production of metal spattering, thus enhancing the welding formation and lowering the welding defects. Among them, the “O” shape scanning trajectory has the best inhibiting effect on metal spattering during welding, which reduces the spattering of the molten metal by 48.8% in the laser linear welding sample. The scanning welding samples under the “O” shape trajectory have flat, continuous, fine and uniform welding seam, with optimal shape, and narrow heat affected zone. The joint has the highest tensile strength of 234 MPa, which can reach 97.5% of the base metal strength. The porosity is the lowest of 1.33%, which is only 38% of the conventional laser linear welding sample. In addition, the highest conductivity is 71.79 mS/m, reaching 91.5% of base metal conductivity.