Increasing the Robustness of Laser Beam Submerged Arc Hybrid Welding in the Presence of Joint Gaps and Offsets

The economic joining of large pipes with large sheet thicknesses is becoming increasingly important in wind turbine construction, not least due to the defined and adopted expansion targets for wind energy. Currently, only conventional arc welding processes such as the gas metal arc welding (GMAW) or the submerged arc welding (SAW) are used for joining these large pipes. Process-induced, a large number of weld passes are required for large sheet thicknesses. This results in considerable costs, which are composed of the energy requirements, weld filler metal and production time, among other things. By combining the laser beam process with the conventional submerged arc welding process in a common process zone, it was possible to develop a high-performance welding process at the Institute of Welding and Joining Technology at RWTH Aachen University that enables more efficient joining in the thick sheet area. With the laser beam submerged arc hybrid welding process (LUPuS Hybrid), it has already been possible to join sheet thicknesses of up to 50 mm using the layer/counterlayer technique in just two weld passes. Therefore, this paper presents the further development of the LUPuS single wire process into the LUPuS tandem process in order to increase the robustness against component tolerances such as joint gaps and offsets. The welds carried out with the newly developed LUPuS tandem hybrid process show that both joint gaps (up to 1.5 mm) and offsets (up to 3 mm) can be performed with high weld quality and reproducibility.