Study on regional different erosion–corrosion behavior and mechanism of Ni1725–W <i>x</i> C laser clad coating under high temperature and pressure environment

Purpose This study aims to investigate the differences in the microstructure of the overlap zone (OZ) and non-overlap zone (NZ) of Ni1725–WxC laser clad coating, compare the erosion–corrosion resistance under varying flow velocities in high-temperature and pressure environments and explain the regional variations in the failure mechanisms. Design/methodology/approach The OZ and NZ of Ni1725–WxC laser clad coating were comparatively analyzed using scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction, electron back scatter diffraction and X-ray photoelectron spectroscopy. The erosion–corrosion resistance was evaluated electrochemically in a high-temperature and high-pressure autoclave. Findings The OZ exhibited inferior corrosion resistance due to grain coarsening, a higher Fe dilution rate and increased secondary phase content. Fluid erosion accelerated corrosion by damaging the protective corrosion product film and enhancing material exchange. Originality/value Investigation from the perspective of local variations reveals the macroscopic inhomogeneity in the corrosion resistance of the Ni1725–WxC laser clad coating.