MULTI-CARBIDE REINFORCED HARDFACING LAYERS ON MILD STEEL: A COMPREHENSIVE REVIEW OF PROCESSING, MICROSTRUCTURE, WEAR MECHANISMS AND FUTURE RESEARCH OPPORTUNITIES

Abstract

Multi-carbide reinforced hardfacing has become an effective strategy for improving the wear resistance and service life of mild steel components used in mining, construction, agriculture, and manufacturing industries. The incorporation of carbides such as WC, Cr₃C₂, TiC, VC, NbC, and complex mixed carbides within a metallic matrix provides synergistic strengthening, resulting in enhanced abrasive, erosive, and adhesive wear resistance while maintaining adequate toughness and crack resistance. These reinforcements refine the microstructure, stabilize the matrix, and strengthen the carbide–matrix interface, leading to superior durability under severe mechanical and thermal loading. This review examines developments in deposition technologies including laser cladding, GMAW, FCAW, SMAW, PTAW, and high-velocity thermal spraying, with a focus on microstructural evolution, carbide dissolution behavior, matrix phase transformations, and wear mechanisms. Performance differences related to heat input, dilution, cooling rate, and carbide distribution are analyzed, along with crack formation, thermal stress response, and tribological behavior. The review concludes by outlining emerging directions such as machine-learning-based process optimization, hybrid and functionally graded hardfacings, and low- dilution additive manufacturing approaches for next-generation wear-resistant surfaces.