Comparative Study of Laser Welding and Laser-Metal Inert Gas (MIG) Hybrid Welding of 5052 Aluminium Alloy

It was found that both laser welding and laser-metal inert gas (MIG) hybrid welding with a fibre laser could be applied to join 5052 aluminium alloy plates successfully; however, the quality of welds from two processes can be quite different. To understand the impacts of the welding processes on the quality of welds, a comparative study was conducted to look into how a welding process can be selected to meet the expected quality of welds. The quality of welds was measured by weld appearance, microstructure and mechanical properties. The reported work has shown the quality difference of welds at the following aspects: (i) on the appearance of welds, the laser-MIG hybrid welding process led to fully reinforced welds, and the laser welding process resulted in uniformly underfilled welds with root sagging; (ii) On the porosity, the welds from the laser-MIG hybrid welding process was larger than that of the laser welding process; (iii) On bead microstructure, the welds from the laser-MIG hybrid welding process were equiaxed dendritic, and the grain sizes in the fusion zone (FZ) were coarser than that from laser welding process; (iv) On the distribution of microhardness, the microhardness at the heat affected zone (HAZ) was lower than that at the FZ and the base metal (BM) in the laser welding process, while the microhardness at the FZ was higher than that in BM; and (v) Finally, the tensile strengths of welds from laser welding process and the laser-MIG hybrid welding process were 174 and 114 MPa, respectively. The tensile strength of welds from the laser welding process was up to 71.71% of that of the substrate.