LaserHybrid Welding and LaserBrazing: State of the Art in Technology and Practice by the Examples of the Audi A8 and VW-Phaeton

Abridged version: In view of the demands made by the end users in the field of application of vehicle construction for an ever-higher product quality and improved performance, continuous innovations are considered to be absolutely decisive for being successful. This especially applies to the welding technology, and therefore the goal is to develop new, better and more powerful welding processes. In joining technology the high welding speed on the one and the good gap bridging ability on the other hand play a significant part. However, both features cannot be achieved by conventional laser welding processes. Therefore, a hybrid process is being applied, the LaserHybrid welding or also called LaserBrazing. It is no doubt that the laser beam welding and the MIG welding have been established in the welding technology for very long, and that both processes allow a wide field of application in the joining technology. New possibilities and synergetic effects, however, are based on the combination of both processes. The laser radiation causes a very narrow thermally affected zone with a high ratio between welding depth and seam width. In the case of the laser welding process the gap bridging ability is very low due to the small focus diameter, however very high welding speeds can be achieved. The MIG welding process features a significantly lower energy density has a larger focused spot on the material surface and is characterised by its good gap bridging ability. The LaserBrazing including an automatised brazing-wire feed-system represents a new joining process with low heat input. Since manual brazing is quite expensive and brings about varying brazing qualities, the use of a process that can be automatised is of highest interest. The laser beam brazing with its easily controllable and accurate energy input has a very high potential in this regard. When welding galvanised steel plates, the coating in the area of the weld seams is damaged or destroyed, and thus the joining area is accordingly susceptible to corrosion, the brazing seam itself, however, does not corrode. While the laser arc welding is applied to aluminium, unalloyed, alloyed and high-alloy steel, the LaserBrazing is especially used with galvanised steels.