Residual Stress, Microstructure, and Characterization of Self-Mated Additive Repair of Inconel 718 Alloy Using Cold Spray Process

Abstract

Inconel 718 was deposited via cold spray process onto Inconel 718 grade base material as a possible alternative repair solution of the hardware after service. A detailed characterization of the thick (~2 mm) coating was carried out, for analyzing the coating porosity, residual stress, and mechanical properties including tensile bond adhesion strength and microstructure (phase stability), in the as sprayed condition. Interfacial chemistry, the coating relaxation behavior, and thermal stability of the cold sprayed coating were studied after heat treatment at relevant temperatures. Detailed metallurgical characterization of the coating, interdiffusion characteristics with the substrate and residual stress measurements, enabled understanding of near net repair of the part as a possible alternative for conventional repair processes known. The overall analysis indicated the coating to be well suited for self-mated near net shape repair application for turbo-machinery components and indicated heat treatment improvements can lead to better mechanical properties in these systems.