Numerical investigation of asymmetric weld fusion geometry in laser welding of aluminium alloy with beam oscillation

In this work, the asymmetric weld fusion geometry in oscillating laser beam welding (OLBW) of aluminium alloy was reported and investigated using a numerical approach. A multi-physics heat transfer and fluid flow model of OLBW was developed and validated with the corresponding experimental results. The weld fusion geometry, temperature fields, and fluid flow behaviours for four commonly used oscillation modes, line, circle, eight, and infinity, were calculated to analyse the origin of the asymmetric weld fusion geometry. The results show the asymmetry of local heat input along beam travelling path and the fluid flow pattern in the molten pool are the main factors that result in the asymmetric weld fusion geometry in OLBW.