Visualization of the molten pool of the laser beam submerged arc hybrid welding process

Submerged arc welding is currently the predominant industrial welding process for joining various steel grades in the plate thickness range of about 40 mm. A high energy input and the associated component distortion are unavoidable due to the high number of welding layers. By combining the conventional submerged arc welding process with the laser beam welding process to form a common hybrid welding process, this welding task can be mastered in only two welding layers by means of layer-counter-layer technology. This considerably reduces the welding time and thermally induced component distortion to a minimum due to the symmetrical energy input. A characteristic feature of a hybrid welding process is the formation of a common weld pool. In previous studies, the mixing of the molten pool has already been proven using chemical analysis methods. In the context of this paper, the shaping of the hybrid weld pool is also discussed. The molten material is expelled out of the joining zone by means of a gas pressure surge. Subsequently, a light section sensor was used to scan this area and produce a three-dimensional image from the formerly molten weld seam area. This shows that a single contiguous melt pool is produced. Finally, the first one-sided welds with full penetration and backing will be presented and discussed.