Microstructural and mechanical properties of AlSi10Mg: Hybrid welding of additively manufactured and cast parts

Welding and joining of hybrid components consisting of additively manufactured (AM) parts and conventionally processed parts offer new opportunities in structural design. In the present study, AlSi10Mg specimens were fabricated using two different manufacturing processes, i.e., laser-based powder-bed fusion of metals (PBF-LB/M) and casting, and welded by means of friction stir welding (FSW). Material strength of dissimilar welded joints was found to be governed by the as-cast material, which is characterized by a very coarse microstructure resulting in inferior hardness and tensile properties. During fatigue testing, cast-cast specimens performed slightly better than their hybrid AM-cast counterparts with respect to lifetime, being rationalized by most pronounced strain inhomogeneities in the AM-cast specimens. With the aim of cost reduction, FSW can be employed to fabricate graded large parts as long as the AM as-built material is placed in the region demanding superior cyclic load-bearing capacity.