Simulation and experiment for dynamics of laser welding keyhole and molten pool at different penetration status

The penetration status profoundly influences the dynamic behaviors of keyhole and molten pool during laser welding. This paper presents a three-dimensional numerical simulation model with a ray-tracing method, which is dedicated to investigating the different penetration statuses in laser welding of type 304 stainless steel. In the proposed model, the factors include melting, evaporation, solidification, the vapor-induced plume heat transfer, buoyancy force, Marangoni effect, surface tension, and recoil pressure. Unlike existing similar work, three types of penetration status are investigated, including non-penetration, insufficient penetration, and full penetration. The weld cross-section geometry of simulation results is in good agreement with the experimental results. The behaviors of keyhole and molten pool, energy absorbed by the weldment, and flow field in the molten pool are discussed in details. It is found that the penetration status affects the dynamics of keyhole and molten pool, the temperature field, the absorbed energy, and the flow field, which is greatly connected with weld bead formation and joint quality.