Understanding Pore Formation in Laser Beam Welding

The mechanisms leading to process pores in deep penetration laser beam welding are discussed in this paper. Process pores were observed since the beginning of laser welding. Although there are differences in the number, size and location of the pores depending on the used laser type and beam parameters, process pores are a common problem for all laser sources. To clarify the mechanisms, basic experiments with transparent materials were performed. During those experiments high-speed videos were recorded and subsequently analysed. Several very interesting insights concerning fluid flow and pore generation could be obtained.