ABSTRAKT

In this study, a unified numerical investigation has been performed on the evolution of the weld pool and keyhole geometry during the low-power and high-power density laser welding. Unsteady phase-change heat transfer and fluid flow with the surface tension are examined. The Modified CSF method is employed to incorporate Marangoni effect with deformable free surface in fixed grid system. The one-dimensional vaporization model is introduced to model the overheated surface temperature and back pressure during high-power density laser welding. It is shown that Marangoni convection in the weld pool is dominant at low-power density laser welding, and the keyhole with thin liquid layer and the hump are visible at high-power density laser welding. It is also shown that the transition from conduction welding to penetration welding for iron plate exists when the incident laser power density is about 10⁶ W/cm²