Laser Wire-Feed Welding versus TIG Welding for Addtitive Repair of 2A50 Aluminum Alloy:Comparsion of Microstructure and Mechanical Property Restoration Effects

Local precision repair is required for the surface damage of 2A50 aluminum alloy components in a certain type of aircraft. Given the characteristics of 2A50 aluminum alloy such as susceptibility to porosity and hot cracking tendency during welding, additive repair tests using ER4043 welding wire were conducted on the samples via TIG welding and 300W low-power pulsed laser wire-filled welding respectively, aiming to explore the optimal repair method. The microstructures, microhardness, and mechanical properties of the repaired zones and fusion zones after welding by the two repair methods were studied.The study found that eutectic silicon precipitated in the repaired zones of both methods. Specifically, a large number of coarse acicular eutectic silicon precipitated in the repaired zone of TIG welding, which was distributed between the dendrites of α-Al. In contrast, the eutectic silicon in the laser-welded repaired zone appeared as fine particles or fibers. Moreover, the grain size in the laser-welded repaired zone was significantly smaller than that in the TIG-welded repaired zone.After repair, the average tensile strengths of the samples repaired by TIG welding and laser welding reached 318.5MPa and 378.5MPa respectively, with fracture elongations of 8.1% and 14% respectively. Therefore, under the laser welding additive repair method, due to the effects of grain refinement strengthening and precipitation strengthening, the comprehensive performance of the repaired zone is more in line with the service standards.