Microwave joining of additive manufactured SS316 with conventional SS316 for hybrid structural applications

Metal additive manufacturing (MAM) can better complement existing methods by providing hybrid structural strengthening and repair solutions. This opportunity and challenge can only be fulfilled by joining additive-manufactured (AM) parts with conventional ones. In this study, AM SS316 is joined with conventional SS316 through selective microwave hybrid heating. The SEM (scanning electron microscopy) images pointed towards non-epitaxial grain evolution along the joint interlayer due to the complete diffusion of Ni. EDS (energy dispersive spectroscopy) mapping exposed the intermixing of Fe from base metal to interlayer and Ni from interlayer to base metal. At the fusion zone, the maximum hardness of 282 HV was determined. Hard carbide phases attributed to increased hardness. A 378 MPa of ultimate tensile stress of weld signifies the exceptional bonding achieved between Ni-Fe. At last, the fractography study revealed both ductile and brittle modes of fracture.