Experimental and numerical study on molten pool dynamics and porosity formation mechanism of laser beam oscillation welding of titanium and aluminum

Abstract

In this study, a numerical model of oscillation weld butt joint is developed to investigate the welding of titanium alloy with aluminum alloy. Two paths, namely straight and sine are used to study the distribution of force in the molten pool, the welding temperature field, and the formation and evolution of porosity within the weld. A 3D Gaussian heat source is used to represent the laser beam. The volume of fluid method is employed to track the gas-liquid free surface, and the gas-liquid interface force is transformed by the continuous surface force model. The mechanism of keyhole collapse and pore formation was examined, along with the fluid flow, surface tension, and recoil pressure on the molten pool. The results confirmed that the highest welding quality is acquired by using a laser welding sine path. Notably, numerical simulation results are validated through experimental data, and sine oscillating laser welding significantly reduced weld seam porosity in the welding of Ti-Al dissimilar alloys. This research provides valuable insights into the fundamental mechanisms of keyhole collapse and pore formation in laser welding, which contributes to the advancement of effective welding strategies for dissimilar alloys.