Study Of High Power CO₂ Laser Welding Technique On T-Lap Joint Of 5083 Alumium Alloy

With the development of weldable aluminum alloy and global light-duty trend of transport facility,T-joint of aluminum alloy have been widely applied in the aerospace,shipbuilding and automobile industry. Due to equipment limitation, it is difficult to extrude that thickness of T-joint is greater than 4mm. The traditional T-joint fillet weld can not be implementing because of limitation of the structure. In this paper, using high power CO2 laser device, T-lap joint of 5083 aluminum alloy was welded by laser welding and laser-MIG hybrid welding. The influences of laser welding parameters were studied, and the defects of the T-lap joints were also analyzed.Firstly, according to the experimental requirements and welding characteristics of T-lap joint of 5083 aluminum alloy, the positioning device and work fixture were designed and optimized. It provided the equipment condition for the experiment of welding process.Secondly, the influences of laser welding parameters on weld formation of T-lap joint of 5083 aluminum alloy were studied. The parameters include laser power, welding speed, laser position and shield gas flow rate. The result shows:With the increase of laser power or the reducing of welding speed, weld penetration, weld width and junction width increase. Laser position and shield gas flow rate have less of an effect on weld size, but will have greater influence on weld defects. With suitable laser welding parameters, the excellent welding seam on overlap welds of 5083 aluminum alloy T-joint, but the select range of process of parameters is relatively narrow.Thirdly, the influences of laser-MIG hybrid welding parameters on weld formation of T-joint of 5083 aluminum alloy were studied,the parameters include laser power, welding speed, wire feeding rate, heat source distance and assembly gap. The result shows:With the increase of laser power or the reducing of welding speed, weld penetration, weld width and junction width increase. Compared with laser welding, weld appearance by laser-MIG hybrid welding is better. But duo to the increase of weld heat input of laser-MIG hybrid welding, the weld is easier to collapse. It is needed to put two copper plates in both sides of web plate with auxiliary forming. T-lap joint of 5083 aluminum alloy can get maximum penetration and junction width when heat source distance in the range of 2mm to 4mm. With the increase of assembly gap between face plate and web plate, weld defects appear in the aluminum T-lap joint.At last, the defects of the T-lap joints of 5083 aluminum alloy were also analyzed. It is compared between weld appearance by laser welding and laser-MIG hybrid welding. The improvement mechanism of laser-MIG hybrid welding on weld porosity and weld appearance were discussed, and the suggestions for improvement of weld defects were provided.