Study on the Effect of Laser Remelting Energy Density on the Microstructure and Wear Resistance of Fe-Based Alloy Coatings Fabricated by Laser Cladding

In this work, Fe-based alloy coatings were prepared on the surface of ductile iron by laser cladding. To improve its wear resistance and consider the economic and time cost of other post-treatment processes, laser remelting was chosen to strengthen the coatings. The effect of laser remelting energy density (0−11.45 J/mm²) on the phase composition, microstructure evolution, hardness, and wear resistance of the coatings were investigated. The results show that the coating consists of γ-(Fe, Cr) and carbides and that remelting energy density has little effect on its phase composition. After remelting, the hardness uniformity of the coating was significantly improved, but increasing the remelting energy density had little effect on it. The hardness and wear resistance of the coatings were inversely related to remelting energy density. At a low remelting energy density of 5.66 J/mm², the hardness and wear mass loss of the coating were 111.49% and 54.36% of the original coating, respectively. The mechanism for the improved hardness and wear resistance is the microstructure refinement induced by laser remelting. Increased remelting energy density reduces the microstructure refinement of the coating, but the coatings still showed good hardness and wear resistance due to the diffuse distribution of carbides at higher remelting energy density conditions of 9.43-11.45 J/mm².