Laser welding with wobbling system of dissimilar nickel superalloys for applications in the aeronautical field

Laser welding process applied to dissimilar nickel superalloys can lead to cracking and embrittlement phenomena. A recent development, called laser welding with “wobbling” technique, allows heat input optimization and has been selected as the most promising solution to prevent defects in aerospace components. A preliminary study was performed comparing conventional TIG, laser and recent laser “wobbling” applied to representative weld specimen characterized from mechanical, microstructural and metallurgical point of view. The results were also assessed with reference to the applicable specifications, which define quality levels of the welds in terms of surface and volumetric defects admissible for aeronautical application. The welding parameters were optimized for the joint studied following an experimental test plan. The improvements achieved with the optimized welding process and “wobbling” technology were finally evaluated on a real application case that was ready for the industrialization phase. At the same time, an automatic welding system was developed with a vision system, dimensional control in real time and multiple robots able to cooperate to obtain the welding of the components, managing all the phases starting from gripping, positioning, spot welding and gas protection. Automation performance has been analyzed to understand its influence on the welding process, the parameters have in fact been optimized so that the entire production cycle is robust and the results of the welding checks are consistent with those of the qualification.