Synthesisand Characterization of WC-Reinforced Fe-Based Coatings by Laser Additive Manufacturing

The microstructures and tribological properties of the WC-reinforced Fe-based thick coatings,synthesized by laser additive manufacturing with WC and Fe-based powders on substrate of 316 L stainless steel,were characterized with X-ray diffraction,scanning electron microscopy,energy dispersive spectroscopy and mechanical probes.The results show that the WC-reinforced Fe-based coating significantly modified the microstructures and tribological properties.Generally speaking,the well-defined boundary formed between the interfacial bonding zone and heat affected zone(HAZ);the cellular grains,fish-bone-like dendric texture and martensite “needles” coexisted in HAZ.The top-down hardness profile decreased from 1026 HV,roughly in three deep-steps,and the depth wear-rate distribution changed in a decrease-increase mode,minimizing to 0.31 mg/mm² and being much lower than that of the substrate.The precipitation of large carbide grains possibly resulted in a stronger surface hardness and a lower friction coefficient.