Gas shielding in fibre laser welding of high strength pipeline steel

Pipeline welding requires mechanised high productivity welding processes to achieve the industry's production demands. Laser welding is a high productivity process in use though there is further scope for development namely by using the recent commercialised high power fibre lasers. Shielding gas is known to have a significant influence on plasma plume characteristics during laser welding and on weld bead profile. This paper presents an analysis of fibre laser weld bead characteristics obtained with different shielding gases. The results indicate that weld profiles are affected by the shielding gas for different welding regimes. Increasing CO2 content results in higher penetrations in medium or shallow keyhole conditions, while argon is beneficial in deep penetration.