This study examines the feasibility of using friction stir welding (FSW) to join laser powder bed fusion (LPBF) additively manufactured Scalmalloy®, A20X, and CuNiSiCr copper alloys. Additively manufactured aluminum and copper alloys are highly valued for their ability to produce complex geometries. However, challenges such as printability issues, defect management, and the limited production volumes achievable with standard LPBF machines contribute to hindering their large-scale adoption. Consequently, researchers are increasingly exploring welding techniques for joining additively manufactured components. While fusion welding introduces challenges related to melting and solidification, solid-state welding methods like FSW offer significant advantages by preserving the engineered microstructures of these materials.

This research investigates the effects of FSW on the quality of butt joints made from 4 mm thick LPBF-manufactured plates of A20X, Scalmalloy®, and CuNiSiCr. A range of rotational and welding speeds was tested to evaluate the influence of the joining process on the mechanical properties and microstructures of these alloys. For the aluminum alloys, FSW produced welds with refined microstructures and only minimal reductions in mechanical strength compared to the base material. In contrast, the CuNiSiCr alloy demonstrated an increase in strength after welding, attributed to the fine-grained microstructure in the stir zone compared to the coarse-grained base material. Furthermore, 3D X-ray computed tomography revealed that metal stirring during the FSW process significantly reduced the intrinsic porosity across all the tested alloys. The study also evaluated hardness profiles, joint appearance, and fractographic analyses, highlighting a strong correlation between microstructural features and mechanical performance. These findings underscore the potential of FSW as an effective joining method for LPBF-manufactured components.