Study on the Evolution Mechanism of molten pool surface morphology of Negative Pressure Arc welding via Fully Coupled Arc-Pool Free Surface Model

The accuracy of thin-walled structures in arc additive manufacturing components is limited by the overflow of molten pool caused by positive pressure arc. Therefore, our team introduced negative pressure arc additive technology, but the research on the mechanism of molten pool movement under negative pressure arc has not been explored yet. Therefore, a fully coupled arc pool model containing free surface deformation is used to study the interactions between heat, force, flow, and free surface morphology under negative pressure conditions in the melt pool. The results indicate that negative pressure arc can effectively improve the depression of the molten pool. With the increase of welding current and magnetic field strength, the electromagnetic stirring force is enhanced, and the molten pool exhibits severe centrifugal phenomenon, leading to an increase in molten pool depression. Negative pressure arc achieves a more uniform distribution of heat input, forming a low-temperature zone in the center of the melt pool. Through the Marangoni effect, a counter current zone is generated, thereby reducing the flow velocity at the center of the molten pool. This study has made significant contributions to understanding the mechanism of molten pool under negative pressure and laid a theoretical foundation for the application of negative pressure arc addition technology.