Investigation of keyhole plume and molten pool based on a three-dimensional dynamic model with sharp interface formulation

Laser keyhole welding is a complicated multi-phases, multi-physics process, especially when assisting gases are involved. A three-dimensional transient model is developed to investigate the dynamics of keyhole, together with the vapour plume and molten pool, in a self-consistent manner. The model features the utilization of sharp interface method for accurate consideration of the complex surface phenomena on the keyhole wall and a comprehensive hydrodynamic calculation for both the vapour plume and molten pool. The model is validated against experiments and the simulation results are discussed. It is found that the interplay of the multiple reflections and the plume attenuation due to particle absorption/scattering is crucial for the laser absorption intensity and hence the temperature on the keyhole wall, and the keyhole wall temperature distribution has profound influences on the fluid flow and temperature/species distributions in both the molten pool and keyhole plume.