PSI - Issue 79

Benjamin Möller et al. / Procedia Structural Integrity 79 (2026) 493–500

496

diameters of d SC =203 μm for the core and d SR =523 μm (outer diameter) for the ring result. In order to create a form fit, the laser processing heads were each tilted at 15°. In order to improve productivity and mechanical properties, an innovative powder- and groove-based method is applied by using two intersecting laser beams for simultaneous welding. The Figure 1 shows the innovative welding methods with details of the individual process steps and the groove geometry, exemplary for welding of one side of the adapter

Figure 1. Innovative welding method and the groove geometry including joining process steps, based on Korschinsky et al. (2025).

In the first step, the grooves with adequate geometries are milled into the aluminum alloy and filled with iron-rich powder. The steel sheet is then positioned on the aluminum alloy and fixed using clamping device. The two intersecting laser beams create a fusion bond between the steel plate, filled grooves and the aluminum alloy. The degree of melting of the aluminum alloy is a total of 20 %. This means that with a groove width of 2 mm, 0.2 mm of aluminum alloy is melted on both sides of the groove. Accordingly, both laser beams are oscillated transversely to the welding direction with a width of approximately 2.4 mm. The angle of both grooves is 15°. The welding processes were developed for the adapters of steel material S355 ( t =5mm) and aluminum alloy AA6082. The T-profile with grooves is welded from both sides after the grooves have been filled with iron welding powder. A detailed description of the groove geometry is given in Figure 1. The T-profile has a thickness of 22 mm at the thickest section and 12 mm at the thinner end, where joining is realized. The thickness of the steel sheet metal for the adapter production is 5 mm. In the course of the welding process development, the parameters welding speed v W and energy per unit length E L calculated from the laser beam power and welding speed were determined, taking into account the groove depth of 2.0mm, with regard to best capture the groove. Previous investigations into laser beam welding of dissimilar joints of S355 steel sheets ( t = 5 mm) and AA6082 aluminum alloy ( t = 12 mm) have shown that a groove depth of t g =2mm and an angle α =15° result in an undercut of approximately of 0.4mm and a high max. cross tension force of approximately 11 kN (average max. cross tension force of 11.2 kN), shown in Korschinsky et al. (2025). Even though, increase groove depths of e. g. t g = 3 mm tend to increase the max. cross tension forces due to an increased form fít, a higher scatter of individual results is found, which are explained by variations of the microstructure at the fusion line. Based on a welding power per seam weld of P L =6 kW, the welding parameters determined are a welding speed of v W =0.75m/min, an energy per unit length of E L =480kJ/m, and a groove depth of t g =2.0 mm have been identified as optimal setting. For further analysis of the steel-aluminum-joint, adapters are manufactured using these parameters and evaluated in terms of seam appearance and mechanical properties. Figure 2 shows a cross-section of the manufactured adapter, as well as microstructural images with information on the average aluminum content in the upper, middle, and lower areas of the weld metal. Microscopic examination of the weld metal shows a relatively deformable structure, which is characterized by a low aluminum content of approximately 5 at% in the weld metal, regardless of the measurement position examined. A homogeneous microstructure matrix consisting of ferritic α mixed crystal and bainitic microstructure forms, which improves ductility and plastic deformation capacity. Such a microstructure is capable of relieving stress without