Effect of Y2O3 Addition on the Properties of Laser-Cladded Coatings on 40Cr Steel

To improve the surface properties of 40Cr steel, Ni45/Y2O3 laser-cladded coatings (L-CCs) were fabricated on the surface of 40Cr steel. The effects of Y2O3 addition (0.5%, 1.0%, and 1.5%) on the microstructure, microhardness, residual stress, wear resistance, and corrosion resistance of the L-CCs were systematically investigated. The results indicate that Y2O3 has a significant effect on enhancing the corrosion resistance and suppressing the residual stress of the L-CCs, whereas its contribution to the improvement of microhardness and wear resistance is relatively limited. Compared with the single Ni45 L-CC, the L-CC containing 1.0% Y2O3 exhibited a 45.9% reduction in corrosion current density and a 79.3% reduction in residual stress. At a Y2O3 addition of 0.5%, the microhardness increased by 4.0%, while the average friction coefficient and wear mass loss decreased by 4.8% and 2.6%, respectively, relative to the single Ni45 L-CC. Excessive Y2O3 addition reduces the fluidity of materials in the molten pool and deteriorates the microstructural uniformity, thereby weakening or even impairing the surface properties of the L-CCs.