Laser additive remanufacturing Ni-based multilayers reinforced with dual-scale tungsten carbides via a novel integrated strategy

Abstract

This study entailed the development of a novel integrated strategy that incorporates hot-wire-feed laser deposition and remelting for repairing stainless steel having WC-Ni composite multilayers reinforced with homogeneously distributed dual-scale tungsten carbide particles. The microstructural characteristics, phase compositions, and microstructural evolution of the composites obtained under three representative combinations of operating parameters were thoroughly investigated. On the basis of the partial dissolution of WC/W2C particles and the temperature variation of the molten pool between laser deposition and remelting, microsized WC particles were successfully synthesized in situ around the large retained WC/W2C in the repaired zone when the optimal energy input during the repair process was employed. Combined atomic-scale high-angle annular dark-field scanning transmission electron microscopy, high-resolution transmission electron microscopy, and ab initio analysis based on density functional theory calculations were employed to reveal the crystallographic orientation relationship between in situ WC and the matrix. The growth mechanism and morphology evolution were clarified. Compared to the substrate, the surface wear resistance of the obtained multilayers was significantly improved owing to the duplex-strengthening effect of the evenly distributed reinforcements in terms of the retained WC/W2C and in situ WC particles. This study affords new insights into the tailoring of reinforcements in composites with excellent wear performance for repairing metallic components.