Scaling laws for the laser welding process in keyhole mode

Abstract

This study shows that the keyhole model derived for determining the scaling laws of keyhole depths for laser welding when high power incident laser beams are used (typically in the multi-kW incident power range), can be also applied to determine the melted depths observed during the Selective Laser Melting process, where much lower incident powers of typically few hundred watts are focused on very small focal spots. The solution of the thermal analysis of this keyhole configuration is described by only three independent dimensionless parameters that are also involved for the analysis of a more general problem of heat conduction using similar input parameters. This global approach and the keyhole model describing the process of laser welding have been also validated by analyzing the melted depths generated by the Selective Laser Melting process. The dependence of the melted depths on the operating parameters of this process has been established, as well as the formation thresholds of the keyhole.