An investigation on plasma-MIG hybrid welding of 5083 aluminum alloy

Plasma-MIG (metal inert-gas) hybrid welding is an advanced welding technology of aluminum alloys, which integrates the advantages of deep penetration in plasma arc welding and excellent filling ability in MIG welding. In this paper, the 5083 aluminum alloy plates with 6-mm thickness were welded using paraxial plasma-MIG hybrid welding. The influence of processing parameters such as the welding speed, plasma current, MIG current, and plasma gas flow rate on the weld forming was investigated, and the microstructure and mechanical behavior of welded joint under the typical parameters were studied. Both the penetration depth and weld width decreased with the increase of welding speed, increased with the increase of MIG current. While plasma arc current and plasma gas flow rate mainly affected penetration depth. The welding joint underwent the different thermal cycles in the different regions, which resulted in the different microstructure. Compared with the lower part of welding joint, the secondary phases in the upper part were bulkier and the dendrite arm spacing was wider, and the width in the partially melted zone (PMZ) was smaller. The tensile strength and the elongation of the welding joint were 274 MPa and 12.42%, which is approximately 85.63 and 95% of that of base metal, respectively.