High-speed synchrotron X-ray investigation of full penetration welding of aluminum sheets

Full-penetration laser beam welding of aluminum alloys is widely applied in industrial welding processes of sheet metal components. It is characterized by a capillary, which fully penetrates two or more sheets in overlap configuration and is open at its top and bottom. Compared to partial penetration laser beam welding, full-penetration welding is associated with a stable capillary and therefore a more reliable process because the additional opening at the bottom side results in the avoidance of a collapsing capillary tip. The behavior of the capillary was analyzed by means of high-speed synchrotron X-ray imaging at the DESY for welding of aluminum sheets with thicknesses of 1 mm. The results prove the stabilization of the capillary if it opens at the bottom side of the sheet. Additionally, a stabilization of the melt-pool isotherm in front of the capillary is observed. Despite the reliable avoidance of capillary collapses, the formation of pores is still observed.