Weld bead formation by 10 kW class high power fiber laser on 16 mm thickness carbon steel plate

In this study, weld characteristics of high power fiber laser welding with a maximum output of 10 kW on thick carbon steel plate were evaluated. Both bead-on-plate and butt joint welding were conducted on SS400 carbon plate of 16 mm thickness under various welding parameters. Acceptable weld profiles with a deep and narrow weld bead and without apparent defects such as undercut and melt-through can be obtained by single pass process at the optimized welding parameters. Porosity was observed in both cases of partially-and fully-penetrated weld beads. From residual gas analysis results of the porosity, trapping of Ar shielding gas was a main reason for porosity formation in the partially-penetrated weld bead, whereas trapping of infiltrated N2 gas from Air atmosphere through keyhole opened in the weld pool on the back side and resultant CO gas were major causes in the fully-penetrated weld bead