Bending fatigue behaviors of the Inconel 718 alloy with a WC-17Co coating at different temperatures

The WC-17Co coating was deposited on the Inconel 718 alloy by high-velocity oxygen fuel (HVOF) thermal spray method. The phase composition and fracture of WC-17Co coatings were investigated by XRD method and SEM, respectively. The bending fatigue behaviors of cantilever specimens were also discussed. The effects of ambient temperature (25, 150, 300°C) on the bending fatigue life were studied in this paper as well. The results showed that fatigue cracks were initiated on the surface coating, then propagated toward the substrate/coating interface, and finally penetrated into the substrate. The bending fatigue life of the coated specimen decreased with the increase of ambient temperature. The average compressive residual stress of WC-17Co coatings decreased after heat treatment. Therefore, a higher crack-propagation rate was induced in the surface coating, resulting in the lower fatigue life of the coated specimen.