Mechanical and microstructural characterization of functionally graded Inconel 825 - SS316L fabricated using wire arc additive manufacturing

This work aims to fabricate the functionally graded Inconel 825 - SS316L wall using the Cold Metal Transfer (CMT) based Wire Arc Additive Manufacturing (WAAM) process. The mechanical behavior of the fabricated wall was appraised with the help of room temperature tensile and microhardness tests on the specimens cut from Inconel 825, SS316L, and the interface regions. Fracture morphology revealed the failure of all the specimens after sufficient plastic deformation, indicating ductile fracture. A change in microhardness was observed at the interface region. The optical micrograph revealed a continuous cellular–dendritic and discontinuous cellular–dendritic region in the Inconel 825 region, whereas the SS316L region was comprised of δ ferrite in the primary austenitic (γ) dendrites. The Energy Dispersive Spectroscopy (EDS) line scans of the FGM wall revealed a gradual change in the Ni and Fe content throughout the interface, signifying a successful fabrication of the FGM.