Microstructure evolution and properties of a laser cladded Ni-Based WC reinforced composite coating

Abstract Laser cladding Ni-based WC reinforced composite coating was fabricated on the surface of Q235 steel using 6 KW fiber laser. The morphology, composition, microhardness and wear resistance of the composite coating at varied contents of WC particles were studied using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), microhardness tester and a wear tester. The results show that the dilution rate of the cladding layer decreases first and then increases with an increase of WC content. When the WC content is 20 wt.-%, the dilution rate is the smallest. In the process of fiber laser cladding Ni-based WC reinforced composite coating, WC particles partially dissolve and interact with other elements to form eutectics, which exist as lumpy shapes, strips and as spherical shapes. By increasing the WC content, the structure of the cladding layer appears to be refined. The main phases of the laser cladding layer are γ-Ni, M7C3, M23C6, CrB, WC and W2C. As the WC content increases, the hardness of the cladding layer increases. When the WC mass fraction reaches 40 wt.-%, the average hardness of the composite coating can be more than five times the substrate. When the mass fraction of WC is 20 wt.-%, the wear resistance of the cladding layer is best, which is more than three times that of Ni60A coating.