Numerical simulation of heat flow coupling in the molten pool of dual-spot laser welding of automotive high-strength steel

High-strength steel is commonly used to manufacture components such as body panels, wheels, and bumpers, which are connected through laser welding. However, issues such as welding distortion, porosity, and oxidation can easily occur during the laser welding process. To address these problems, researchers have proposed using dual-spot laser welding for automotive high-strength steel. Currently, research on dual-spot laser welding mainly focuses on welding formation and weld quality, with limited studies on the flow mechanisms of the molten pool. This lack of understanding hinders the effective application of dual-spot laser welding processes. Therefore, this paper first establishes a three-dimensional transient numerical model for heat flow coupling in the molten pool of dual-spot laser welding of high-strength steel. Then, using a single-variable control method, it investigates the influence of beam distance, welding speed, and laser power on the temperature field of the molten pool. Finally, an analysis of the flow field is conducted to reveal the flow characteristics during the dual-spot laser welding of high-strength steel. Research shows that as the beam distance increases, the size of the molten pool begins to decrease, while the thermal distribution becomes more uniform. Increasing laser power and welding speed help to reduce the formation of welding defects such as porosity and hump defects. This study provides a theoretical basis for the formulation and optimization of welding parameters.