(p665) Laser Submerged Arc Welding (LUPuS) - a new method for longitudinal welded pipes

摘要

The laser beam-submerged arc hybrid welding method originates from the knowledge that, with increasingpenetration depth, the laser beam process has a tendency to pore formation in the lower weld regions. Thecoupling with the energy-efficient submerged-arc process improves degassing and reduces the tendency to poreformation. The newly developed hybrid welding process allows the welding of plates with a thickness larger than20° mm in a single pass and the welding of thicker plates with the double-sided single pass technique.In this special hybrid process, the use of CO2-lasers causes problems when forward sliding flux of slag meets thelaser beam path and forms an uncontrollable plasma plume in the beam path. This plasma then shields the workpiece from the laser power and thus provokes the collapse of the laser keyhole and leads to process in-stability.The substitution of the CO2-laser with a modern solid-state laser significantly improves the performance and thestability of the hybrid process. This contribution will demonstrate the latest results and improvements by means ofwelding results gained with steel plates with a thickness of up to 51 mm.