Microstructure and properties of 6061/2A12 dissimilar aluminum alloy weld by laser oscillation scanning

Abstract

The development of high-power galvanometer provides a new way to solve Low weld strength of dissimilar aluminum alloy in the packaging of new energy power batteries. The effect of laser scanning frequency and amplitude on microstructure and properties of 6061/2A12 dissimilar aluminum alloy weld was studied in this paper. Scanning electron microscope (SEM), X-ray diffraction (XRD) and electron backscatter diffraction pattern (EBSD) were used to detect the microstructure morphology, composition and distribution of the weld. The results showed that increasing laser scanning frequency and amplitude was beneficial to increase the proportion of equiaxed grains in fusion zone and decrease the average diameter of equiaxed grains. The reason was that stirring action of scanning beam increased the heterogeneous nucleated particles in molten pool. The tensile test showed that scanning laser can't increase the hardness and tensile strength, but it was beneficial to increase the elongation, and the maximum is 120% higher than that of non-scanning weld. By increasing the scanning frequency and amplitude, the fracture location of weld gradually changed from fusion zone to the heat-affected zone. The analysis showed that scanning laser makes Cu element in the weld evenly distributed, and the θ-Al2Cu phase and s-Al2CuMg strengthening phase increase, which increased the strength of weld fusion zone. The research results provide a new way to improve the packaging strength, safety and service life of new energy power batteries.