Microstructural study and mechanical properties of TIG welded Inconel 617 superalloy

• Main Authors: Mandal, P.K., Michael Saji, Amal, Kurian Lalu, Akash, Krishnan, Akshay, Nair, Aswin S., Jacob, Manu M.
• Format: Conference Proceeding
• Language: English
• Subjects: CT (−196 ℃); High UTS and ductility; Impact toughness; Inconel 617; PWHT; γ' precipitates
• ISSN: 2214-7853; 2214-7853
• DOI: 10.1016/j.matpr.2022.04.400

Inconel 617 (Ni-Cr-Co-Mo alloy) is a solid solution strengthening nickel-based superalloy and it has been widely used in high-temperature applications because of its excellent oxidation resistance, good creep-rupture strength and superior mechanical properties. Superalloy has been developed for high-temperature strength through solid solution strengthening, and precipitation strengthening from γ' secondary phase precipitates and carbides. It is well-known that the shearing of γ' precipitates mainly contribute to the strength of polycrystalline superalloys. Above 650℃ the precipitation of intermetallic phases (Ni3Mo, (Ni3(Al, Ti)) contributes to the strengthening of the matrix. The Vickers hardness had been measured through TIG welded zone after PWHT at 950 ℃ for 4 h. High hardness has been preserved owing to better coherency between coarse carbides (M23C6), γ' phases and γ matrix. The CVN impact test was carried out at RT and different ranges of CT (−100 ℃ to −196 ℃) with various dipping times. The impact strength obtained at RT and in the heat treated conditions, the as-welded sample of 1.81 J/mm2 at RT, after CT (−196 ℃) of 1.13 J/mm2, respectively. The AR sample exhibits 2.08 J/mm2 at RT, and 1.69 J/mm2 at CT, respectively. Impact toughness is remarkably reduced after CT with various dipping times because of the segregation mechanism of coarse carbides on the grain boundary and faster hardening effects. In the AW with PWHT condition, the tensile properties are obtained likely to UTS of 391.66 MPa, YS of 347.66 MPa, elongation of 8.94%, RA of 7.9%, and YS/UTS ratio of 0.89. In addition, microstructural studies are also examined meticulously to investigate and correlate the structural changes with mechanical properties after CT of the superalloy.