Numerical analysis of gravity-induced coupling dynamics of keyhole and molten pool in laser welding

The dynamics and flow behavior of the molten pool and keyhole during laser welding under the influence of lateral gravity engender a distinct propensity for fluctuation, thereby manifesting a substantial influence on the quality of the laser welding process. Nevertheless, a comprehensive elucidation of these intricately interconnected dynamic mechanisms across varying gravity angles still stands as an unmet imperative. Based on the experimentally validated heat source model, the flow behavior of distorted molten pools and the dynamic evolution of keyholes under varying lateral gravity conditions were investigated. This study elucidates the impact of lateral gravity angle fluctuations on the fluid dynamics proximate to the keyhole, notably accentuated during the molten pool's growth phase. The influence of gravity manifests in a conspicuous demarcation line within the molten pool adjacent to the keyhole. The upper domain of the molten pool is subject to the Marangoni effect, inducing an upward flow, whereas the lower domain undergoes downward motion due to gravitational forces. Furthermore, as the lateral gravity angle increases, there is a notable reduction in the maximum flow velocity within the molten pool.