In shipbuilding, thick dissimilar joints of steel and aluminum are in great demand to reduce weight and center of gravity of ships. On the one hand, dissimilar joints lead to reduction in CO2-emissions as result of lower fuel consumption and on the other hand to higher ship stability. The joining process used for manufacturing ships employs explosive welded adapters to join both dissimilar parts. However, production of these adapters is complex, time-consuming and costly. Furthermore, these adapters have oversized thickness, depending on material thickness of steel and aluminum alloy, in order to achieve required seam strength. There is high interest for an efficient alternative.

In this study, high-power laser beam welding processes are developed for joining steel S355 (5 mm) with aluminum alloy AA6082 (12 mm) in lap configuration with two intersecting laser beams and additional material to increase weld seam quality. Within this framework, two laser beam sources with a max. output power of 6 kW are used to weld dissimilar joints with additional material filled groove. In the course of welding process development, influence of parameters regarding groove depth on metallurgical and mechanical properties is investigated. Adequate process parameters are transferred to laser beam welding of adapters. The adapters are characterized for example by using metallographic analysis and tensile tests. A result is that the adapters reach max. tensile force of approximately 35 kN and break occurs outside of the dissimilar joints. The results increase application potential of laser beam welded dissimilar joints in the field of shipbuilding.