Beam hole behaviour during laser beam welding

Fundamental phenomena during laser beam welding in steel and glass, including beam hole shape, molten metal flow and peculiar plasma behaviour, were observed dynamically using a transmission X-ray system and high speed camera. The effect of altering the flow rate of helium assist gas were also studied. It was found that the gas flow rate had a strong effect on the beam hole shape, molten metal flow and plasma production. In order to avoid the interference effect of laser plasma, a new laser welding process, which we have named “Laser Spike Seam Welding”, was developed. This process allows considerably deeper penetration than conventional continuous welding. The reasons for this superiority were analyzed by the above high-speed film method.