Effect of laser cladding process parameters on the microstructure and corrosion resistance of Ni55A alloy coatings on Q235 steel

Abstract

This study investigated the effects of process parameters on the microstructure and corrosion resistance of laser cladding Ni55A alloy coatings on Q235 steel surfaces. X-ray diffraction, electrochemical analysis, salt spray corrosion experiments, and electron back scatter diffraction were used to study the effects of process parameters on organization and corrosion of coatings. The results show that the physical phase of the coating consists mainly of γ-(Fe,Ni) solid solution and M₂₃C₆. Compared to the base material, the corrosion resistance of coatings is improved to different degrees, with the best corrosion resistance of the coating obtained at a laser power of 1800 W and a scanning rate of 11 mm/s. This is mainly because lower laser power or higher scanning rate can reduce the heat input of the coatings, resulting in a decrease in the grain size, an increase in the percentage of recrystallized grains, and a weakening of the preferred orientation, thereby improving the corrosion resistance of the coatings.