Effect of droplet transfer on pore formation in laser-pulsed metal inert gas hybrid welding of A7N01P aluminum alloy

The effect of welding parameters on the pore formation in laser-pulsed metal inert gas (MIG) hybrid welding of A7N01P-T4 aluminum alloy was investigated. The formation and dynamic behavior of keyholes at different wire feeding speeds were studied using a “sandwich” structure consisting of GG17 glass and A7N01P-T4 aluminum alloy. The types and morphology of pores were analyzed using scanning electron microscopy and an x-ray nondestructive tester. The experimental results indicated that the droplet transfer mode affected the stability of the keyholes. The barrier effect of the large droplets on the laser could cause the bottom of the keyholes to close, forming keyhole-induced pores in the molten pool. The size of the droplet decreased with increasing wire feeding speed; thus, the selection of an appropriate wire feeding speed in laser-pulsed MIG hybrid welding could reduce the barrier effect and effectively reduce the formation of processing pores in the welding seam.