Effect of Buffer Layer on Crack Susceptibility, Mechanical and Microstructural Properties of Ni Hard Coatings

Laser cladding is one of the hard coating techniques used for repairing worn-out or rebuilding damaged components. In the present study, N480 and N9062 alloys were cladded on SS410 substrate with Inconel 625 as buffer layer. Investigations are carried to understand the effect of buffer layer on crack formation, microstructural and mechanical properties of the cladded materials. The clad microstructure is studied using scanning electron microscopy and energy dispersive spectroscopy. The coating micro-hardness measured along the depth has increased by 5–7% due to reduced dilution and diffusion of the substrate elements into the hard coating. The buffer layer addition acts as a heat sink, in turn, playing a key role in attaining fine microstructure, also reducing the thermal gradient between hard layer and substrate ensuring more uniform cooling.