Optimizing high mass flow parameters for high rate laser metal deposition of dense tungsten carbide iron composites

Laser metal deposition (LMD) is a vital technology for the repair and surface protection of large-scale engineering components. Yet, its broader adoption within Industry 5.0 remains constrained by low deposition rates and the propensity for defects when high ceramic reinforcement fractions are employed. This study examined the LMD of an Fe-based self-fluxing alloy reinforced with 50 wt% WC at powder feed rates ( F ) of 45–140 g/min, laser energy densities ( E ) of 7.5–15 J/mm 2 , and interaction times ( T ) of 0.022–0.045 s. Systematic variation of scanning speed ( v ) and powder feed rate ( F ), supported by ANOVA, identified a stable processing window characterized by low energy density, short interaction time, and high F . Within this window, the dense powder stream produced a pronounced shielding effect that limited dilution to <10 %, suppressed excessive carbide dissolution, and stabilized the melt pool, yielding fully dense, near-defect-free deposits with uniformly distributed, largely intact spherical WC particles and only localized interfacial dissolution. At the optimum condition ( E = 12 J/mm 2 , F = 90 g/min), matrix hardness reached 550 HV through dendritic refinement and secondary carbide precipitation, while build rate and melting efficiency were simultaneously maximized. These outcomes enable thick, high-integrity layers at industrially relevant productivity levels. This achievement directly advances circular manufacturing by enabling high-rate, near-defect-free remanufacturing and protective coating strategies that extend component service life, reduce virgin-material consumption, and lower embodied energy. The results thereby align LMD with Industry 5.0 human-centric production and contribute measurably to the UN Sustainable Development Goals through enhanced resource efficiency and sustainable materials use in the energy, automotive, and heavy-industry sectors.