Laser-MIG Hybrid Keyhole Welded 6mm Steel/Aluminum Butt Joints

At present, the connection of steel/aluminum joints has been widely used in industrial fields such as aerospace, marine and automotive.Although the joints with excellent performance can be obtained by the solid phase welding methods such as explosion welding and friction welding, the production process is complicated and the efficiency is low, and the practical application is limited.Laser welding has attracted a lot of attention from researchers because of its advantages of high energy density, small welding deformation and fast welding speed.However, in the single-beam laser welding process, there are problems such as high joint assembly precision, excessive energy density, and easy formation of depressions in the weld.The newly developed laser-MIG (Metal Inert Gas) hybrid welding not only retains the advantages of laser welding, but also fully exploits the advantages of MIG welding, improves weld formation, improves the stability of the welding process, and helps solve the single-beam laser welding problems.In this paper, the laser deep penetration welding process of 5.5 mm thick E36 steel and 6 mm thick 5083 aluminum alloy butt joint was studied by laser-MIG composite welding heat source. Compared with the single laser welding process, the influence of wire feed speed on the welded steel/aluminum joint, joint interface structure and joint mechanical properties was studied.The results show that the laser-MIG composite deep-melt welding can obtain good steel/aluminum butt joint performance. At a laser power of 3.25 kW, a wire feed speed of 1.5 m / min, a laser offset of 0.5 mm and a defocus of 0 mm, the tensile strength of the steel/aluminum butt joint is as high as 85.0 MPa.Laser-MIG hybrid welding can improve the dent defects of a single laser welded steel/aluminum butt joint. The amount of acicular Fe4Al13 phase in the intermetallic compound was significantly reduced, and the resistance of the steel/aluminum joint was increased from 8.6 kN to 12.7 kN.