Abstract
Inconel 718 plates were butt welded through microwave hybrid heating (MHH) technique using Inconel 718 powder as a sandwich layer. Joining was affected through the fusion of the sandwich layer pre-placed between the bulk pieces owing to the heat generated while irradiated with 2.45 GHz microwaves for 480 s. Various phases present in the joint zone were detected using X-ray diffraction (XRD) while the microstructural features were characterized using an optical microscopy and scanning electron microscopy (SEM). The XRD patterns show the presence of Laves, δ(Ni3Nb) and carbide phases in the joint zone along with the main matrix. The microstructural study also reveals that there is not any interfacial cracking and microfissure in the joint zone due to uniform heating associated with the MHH process. The average microhardness of the joint was observed to be 245 ± 20 HV. The average ultimate tensile strength of the joint was observed to be 780 MPa with 11.11 % elongation.

Key words
microwave, Inconel 718, hybrid heating, microstructure, Laves phases

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