Effect of the weld parameter strategy on mechanical properties of double-sided laser-welded 2195 Al-Li alloy joints with filler wire

Compared with single-sided welding, double-sided welding can melt through thicker workpieces and improve the mechanical performance of the weld. In this work, laser welding with filler wire of 2195 Al-Li alloy plates is conducted via double-sided out-of-sync welding. By combining experiment and numerical simulation results, the influence laws of the weld's mechanical properties are studied by considering the condition of both sides under different welding parameters. The results show that the welding speed is the key parameter determining the heat input of the weld. In the welds fabricated at slow welding speeds, the cooling rate is greater, resulting in accelerated solidification. The weld solidifies before hydrogen overflows from the weld pool, resulting in increased pore density and weakened mechanical properties. Therefore, welding parameters determine the heat input of the weld and subsequently the mechanical properties. It is shown that a special double-sided welding strategy can effectively control the heat input. Specifically, in contrast to those of the first, the welding parameters of the second side of the weld reduce the wire feeding speed when other parameters are held constant. Compared with the process strategy using identical double-sided parameters, this can slightly increase the heat input and reduce the defects in the weld, which can improve its mechanical properties. In the comparative experiment, the wire feeding speed was reduced from 5 to 3 mm center dot s(-1), and the tensile strength of the weld was increased by 10%.