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.

本研究针对铝合金摆动激光束焊接（Oscillating Laser Beam Welding, OLBW）中的非对称焊缝熔合形貌展开探究，采用数值方法开展相关研究。构建了摆动激光束焊接的多物理场传热与流体流动模型，并通过配套实验结果完成模型验证。针对直线、圆形、8字形、∞形四种常用摆动模式，分别计算了焊缝熔合形貌、温度场及熔池流体流动行为，以解析非对称焊缝熔合形貌的成因。研究结果表明，沿光束行进路径的局部热输入不对称性与熔池内流体流动模式，是导致摆动激光束焊接中非对称焊缝熔合形貌的主要因素。