Influence of scan paths on flow dynamics and weld formations during oscillating laser welding of 5A06 aluminum alloy

Numerical simulations and experiments are conducted to investigate the influence of three different scan paths, namely straight, sine, and cycloid, on the flow dynamics and weld formation during the laser welding of 5A06 aluminum alloys. The cycloid scan path produced molten pools with the largest dimensions, most regular morphology, and lowest temperature gradients. And the shallowest keyhole with the highest stability and the lowest temperature is produced under this condition, which has the effect of reducing and homogenizing the distribution of the fluid velocity. The most complicated vortices are obtained when the cycloid scan path is used. Porosity ratios of 5.5, 4.9, and 0.59 are obtained when the scan paths are straight, sine, and cycloid, respectively. The large and stable molten pool, the shallow keyhole, as well as the low and highly homogeneous melt flow velocity and the complicated vortices, contribute to reduction in porosity formation.