Custom beam shaping for high-power fiber laser welding

High-power, high-beam-quality fiber lasers can produce high depth/width aspect ratio welds at productive travel speeds with minimal distortion. However, autogenous laser welds made at high-power density often also have sharp toe angles and undercut at the weld toes. In this research, welds were made with a 10-kW IPG fiber laser and a multispectral zinc sulfide beam-shaping optic designed to direct a portion of the beam to the sides of the weld pool to increase melt spreading and smooth the weld toes in a single pass. Toe angles of stainless steel welds were improved using the beam-shaping optic and experimentally optimized parameters. Externally measured toe angles of welds made with a conventional focus optic were 125 deg, while those made with the custom optic were 163 deg,