Investigation of spatter occurrence in remote laser spiral welding of zinc-coated steels

Abstract

This paper discusses the unique application of numerical modeling of remote laser spiral spot welding of zinc-coated steels to reduce spatter occurrence. A thermo-fluid process simulation model was developed to simulate the laser-material interaction, material melting, keyhole formation and molten pool dynamics occurring in remote laser spiral spot welding of zinc-coated steels. Based upon numerically calculated thermal profiles during welding, the instantaneous zinc vapor pressure between faying surfaces was estimated. It was found that high vapor pressure points correlated well with spattering events observed in high-speed videos taken of the molten pool during welding. Using the estimated zinc vapor pressure as an indicator of spatter occurrence, the welding schedule was redesigned to limit high zinc vapor pressure and rapid pressure increase for spatter prevention. The revised schedule was verified by physical testing and resulted in greatly reduced spatter.