Evaluation of microstructure, nanoindentation and corrosion behavior of laser cladded Stellite-6 alloy on Inconel-625 substrate

Abstract

Inconel-625 (IN-625) is one of the widely used high-temperature alloys in various areas of application. Its outstanding characteristics like thermal stability, low density, higher yield strength and oxidation resistance makes it to get implemented in areas including supercritical boilers, heat exchangers, nuclear and pressurized water reactors. In severe aggressive environments, the surface of this alloy is prone to wear and corrosion attacks which leads to sudden failure of the components. This work has attempted to improve the corrosion resistance of the IN-625 alloy by depositing the Stellite-6 particles through the laser cladding technique. The cladded sample was cross-sectioned to analyze the microstructure using the FESEM technique. The nanohardness test has been carried out to evaluate the hardness offered by both the base and the cladded region. The corrosion (uniform type) behavior was analyzed in an electrochemical way on both the base and the cladded samples for different time periods. In addition, the EIS technique was used to evaluate the enhancements in the corrosion resistance of the samples followed by the surface roughness examination. Results showed that the hypoeutectic structure was obtained on the cladded region due to the influence of Co-rich dendritic and Cr-rich inter-dendritic eutectic phases. The cladded region exhibited higher hardness than the base region. Moreover, the cladded sample with 17 h time interval exhibited greater resistance towards corrosion compared with the other duration samples. The formation of oxide has been the major key factor for the enhancement of corrosion resistance. In addition to that, 17 h cladded specimen experienced minimized surface roughness with increased corrosion resistance.