Microstructural evolution and mechanical performance correlation of WC-reinforced iron-based coatings fabricated by laser cladding

In laser cladding, iron-based alloy coatings are prone to issues including microstructural inhomogeneity, elemental segregation, and weak interfacial bonding under high energy density and complex thermal cycling. In this study, WC particles were incorporated as a reinforcing phase into an iron-based matrix to enhance coating densification and achieve synergistic multi-property optimization. Composite coatings composed of a nickel-enriched iron-based matrix and WC were deposited onto H13 tool steel substrates using coaxial powder-feeding fiber laser cladding. The dissolution characteristics of WC particles, elemental diffusion behavior, and phase transformation were systematically characterized via SEM, EDS, XRD, and EBSD. The overall performance was assessed through microhardness testing, tribological evaluation under friction-wear conditions, and electrochemical polarization measurements.Results demonstrate that under the laser processing parameters used in this study, the coating formed a smooth and dense metallurgically bonded interface. In the high-temperature molten pool, partial dissolution of WC particles facilitated reactions with the Fe matrix, resulting in the formation of dispersed strengthening phases (Fe₃W₃C and Fe₇C₃) and substantial grain refinement. The cladding layer demonstrated outstanding performance, with an average hardness of 892 HV0.2-approximately 80% higher than that of the substrate-a wear rate reduced to 38% of the substrate's value, and a corrosion current density lowered by roughly 69%, indicating excellent wear and corrosion resistance. The partial dissolution of WC particles and the associated elemental diffusion behavior provide favorable conditions for the formation of carbide phases, while simultaneously promoting grain refinement and strengthening effects to a certain extent. The synergistic interaction between the refined grain structure and the dispersed carbide phases collectively contributes to a pronounced multi-mechanism strengthening effect. These results offer experimentally verifiable evidence and theoretical backing for microstructural control and performance enhancement in iron-based composite coatings.