Effect of filler materials on the porosity formation of aluminum alloy by laser welding with filler wire

Porosity is a critical defect in aluminum alloys during laser welding. In this study, three filler wires with different Mg content were used to study the effect of Mg on the porosity formation in laser wire filling welding. The increase of Mg content of filler wire leads to the increase of recoil pressure and decrease the surface tension of keyhole wall, which promotes the molten filler wire with more Mg content to transfer to keyhole. The molten droplets flow down the front wall of the keyhole and connect with the protrusion of the rear wall, resulting in the collapse of the keyhole. Therefore, the porosity is more likely to occur in the laser welding with higher Mg content filler wire.