Enhanced corrosion resistance of high speed laser-cladded Ni/316L alloy coating by heat treatment

Abstract

The heat treatment was performed on the high speed laser-cladded Ni/316L coating to improve the corrosion resistance. The coatings were heat treated at temperatures of 650 °C, 700 °C, 750 °C and 800 °C, respectively. The results show that the porosity of the coating was independent of the annealing temperature and the chemical composition of the coating could be perfectly retained after heat treatment. The grain size first decreased and then increased with heat treatment temperature. The content of equiaxed grains and the Fe19Ni precipitation phase increased with increasing temperature. Due to the precipitation, the corrosion resistance of the heat-treated coating was higher than that of the as-cladded coating. Based on the coupled effect of precipitation and grain morphology, the corrosion resistance of the heat-treated coating first increased and then decreased. Therefore, the corrosion resistance could be improved by annealing, but need applicable parameters.

Keywords

• High speed laser cladding
• Heat treatment
• Ni/316L coating
• Corrosion resistance