Processing of High-Quality WC-Inconel 625 Coating via DED

This study examines the effects of laser power (P), scanning speed (SS), and energy density (ED) on the microstructure and hardness of WC-reinforced Inconel 625 metallic matrix composite (MMC) coatings fabricated via a powder-based directed energy deposition (DED) process developed by Makino Asia Pte Ltd. Coating layers were evaluated for surface roughness (Sa), layer height (LH), porosity (Pr), dilution height (DH), dilution ratio (DR), and WC retention (WC%). Trends in the data reveal how process parameters influence deposition quality and microstructural evolution: higher P or lower SS increased melt pool depth, promoted WC dissolution, and coarsened microstructure, whereas lower P or higher SS preserved WC particles and minimized substrate dilution. Hardness variations in the Inconel 625 matrix were associated with dendrite size, solid-solution strengthening, dislocation density, and secondary carbide formation. These findings provide quantitative guidance for selecting DED parameters to produce crack-free WC-Inconel 625 MMC coatings with controlled microstructure and tailored mechanical properties.