Microstructure and Property Evolution of Laser Cladded Fe-Based Coatings on Cast Iron Modulated by WC Ceramic Particles

To realize the remanufacturing of cast iron components, a WC-reinforced Fe-based composite powder was designed, and the WC/Fe-based composite coating was deposited on the HT250 substrate by laser cladding. The melting and dissolution mechanism of WC ceramic particles were investigated, and their influences on the microstructure, phase, microhardness, and wear resistance of the composite coatings were systematically analyzed. The results show that the WC/Fe-based composite coating achieves good metallurgical bonding with the HT250 substrate and possesses excellent forming quality. The incorporated WC particles can effectively optimize the microstructural morphology, acting as heterogeneous nucleation sites and inhibiting grain growth. As WC content increases, the grain size within the composite coating gradually refines. Moreover, partially melted WC particles release tungsten (W) and carbon (C) elements into the molten pool, promoting the in-situ generation of new hard phases, including W2C and Fe6W6C. These newly formed phases, together with the residual unmelted WC particles, contribute a dispersion strengthening effect and improve the properties of the composite coatings. This effect becomes more pronounced with higher WC content. Notably, the composite coating with 20% WC exhibits a microhardness over twice that of the HT250 substrate, while its wear rate is only one-sixth that of the substrate and its corrosion resistance is much higher than that of the HT250 substrate.