Effect of process parameters on the morphology of aluminum/copper alloy lap joints by red and blue hybrid laser welding

In order to overcome the problems of many pores, large deformation and unstable weld quality of traditional laser welded aluminum-copper alloy joints, a red-blue dual-beam laser source and a swinging laser were introduced for welding. T2 copper and 6063 aluminum thin plates were lap welded by coaxial dual-beam laser welding. The morphology of weld cross section was compared to explore the influence of process parameters on the formation of lap joints. The microstructure characteristics of the weld zone were observed and compared by optical microscope. The results show that the addition of laser beam swing can eliminate the internal pores of the weld. With the increase of the swing width, the weld depth decreases, and the weld width increases first and then decreases. The influence of welding speed on the weld cross section morphology is similar to that of swing width. With the increase of welding speed, the weld width increases first and then decreases, while the weld depth decreases all the time. This is because that the red laser is used as the main heat source to melt the base metals, with the increase of red laser power, the weld depth increases. As an auxiliary laser source, blue laser reduces the total energy consumption, consequently, the effective heat input increases and the spatter is restrained effectively. As a result, the increase of red laser power has an enhancement effect on the weld width and weld depth. When the swing width is 1.2 mm, the red laser power is 550 W, the blue laser power is 500 W, and the welding speed is 35 mm/s, the weld forming is the best. The lap joint of T2 copper and 6063 aluminum alloy thin plate can be connected stably with the hybrid of blue laser. The effect rules of laser beam swing on the weld formation were obtained, which improved the quality of the joints.