Effect of beam shaping on spatter suppression in keyhole welding using 16kW disk laser

Laser welding is widely used in various fields, such as heavy industry and the automotive industry, due to its ability to achieve deep penetration into materials and its excellent compatibility with automation. When a laser is irradiated on a metal material, the surface absorbs the light, causing the metal to heat above its melting point and form a molten pool. Part of the molten pool vaporizes into metal vapor, which diffuses and exerts recoil pressure on the molten pool, creating a cavity known as a capillary. Deep penetration can be achieved by reflecting the laser beam within the capillary. However, this process also causes the metal vapor to engulf portions of the molten pool and disperse, leading to a phenomenon known as spattering. Spattering results in material loss and voids, ultimately reducing weld quality, making it crucial to suppress spatter during the welding process. Previous studies have shown that splitting the laser beam into three spots for irradiation significantly reduces spattering compared to single-spot irradiation. However, the mechanism by which 3-spot irradiation reduces spattering remains unclear. In this study, welding was performed using a 3-spot laser, and capillary dynamics were observed with an x-ray transmission system. The results revealed that the enlargement of the capillary aperture contributed to the reduction of spatter.