Laser powder bed fusion (LPBF) is particularly well suited for the production of geometrically complex functional metal components. However, the size of the components that can be produced is limited technologically by the volume of the construction chamber, and economically by the low build‐up rates. With the provision of a reliable welding technology, size limitations can potentially be overcome to a degree by joining two additively manufactured (AM) components or by hybrid construction of components. Therefore, this study investigates the production of hybrid joints from additively and conventionally manufactured AlSi10Mg material by electron beam welding (EBW). It is known that EBW of LPBF‐processed aluminum alloys in the keyhole welding mode results in the distinctive formation of pores in the weld seams. To avoid this, two different joining strategies are pursued, namely, beam offset and multispot welding methods. It is thus determined that an adequate weld seam quality can only be achieved by means of a three‐spot welding process with adapted EB parameters. Accordingly, the investigations prove the applicability of the EB keyhole welding mode in EBW for the production of low‐porosity LPBF mixed joints.

Nitriding of Al alloys leads to the formation of a thin, hard nitride layer (AlN) on the surface. A subsequent EBR can both eliminate the nitriding-related cavities under the nitride layer and increase the hardness of the substrate without melting or destroying the nitride layer. This paper deals with investigations regarding the influence of the energy/heat input on the microstructure within both the AlN layer and the remelted Al substrate. Of particular interest was the interface between the AlN and the Al substrate, which changed to a transition zone with a depth of approximately 80 µm. A range of high-resolution imaging and analytical tools for both scanning and transmission electron microscopy were used for these investigations. Based on the findings from the microstructural investigations, a schematic model was developed of the processes occurring within the nitride layer and at the interface as a result of remelting.