Effect of Laser Power on Microstructure and Properties of Aluminum/Steel Laser Butt Welding-Brazing Joint

Laser butt welding-brazing was conducted on 6061-T6 aluminum alloy and galvanized Q235A steel at different laser powers (1.0-1.4 kW) with Er2319 wire as filler metal. The effect of laser power on microstructure and tensile properties of the joint was studied. The results show that aluminum alloy and steel could be effectively connected at the laser power of 1.1-1.3 kW, and when the laser power was 1.2 kW, the forming quality was the best. At the laser power of 1.1, 1.2 kW, a large number of equiaxed crystals and a small number of broken dendrites were formed in the weld, and at the laser power of 1.3 kW, the microstructure mainly consisted of coarse acicular crystals. The thickness of the intermetallic compound layer at the interface of the joint at the laser power of 1.2 kW was less than that at the laser power of 1.1 kW. The tensile strength of the joints increased first and then decreased with increasing laser power, and was the largest (107.43 MPa) at the laser power of 1.2 kW; the joint showed a mixed fracture mode of ductile and brittle.