17-4 PH and SS316L bimetallic structures via additive manufacturing

Balancing strength and ductility is crucial for structural materials, yet often presents a paradoxical challenge. This research focuses on crafting a unique bimetallic structure, combining non-magnetic, stainless steel 316L (SS316L) with limited strength but enhanced ductility and magnetic, martensitic 17-4 PH with higher strength but lower ductility. Utilising a powder-based laser-directed energy deposition (L-DED) system, two vertical bimetallic configurations (SS316L/17-4 PH) and a radial bimetallic structure (SS316L core encased in 17-4 PH) were fabricated. Monolithic SS316L, 17-4 PH, and a 50% SS316L/50% 17-4 PH mixture were printed. The printed samples' phase, microstructure, room temperature mechanical properties, and fracture morphology were examined in as-printed conditions. Bimetallic samples exhibited both phases, with a smooth grain transition at the interface. Radial bimetallic samples demonstrated higher mechanical strength than other compositions, except 17-4 PH. These findings showcase the potential of the L-DED approach for creating functional components with tailored mechanical properties.