Microstructure and wear behavior of WC/Co50 composite coatings on 40Cr cutting tool surface prepared by laser cladding

WC/Co50 cladding coating was fabricated on 40Cr cutting tool surface by 6 kW transverse-flows multimode CO2 laser apparatus. The surface morphology, phase composition, microstructure, microhardness and wear behavior of the cladding coating were analyzed by optical microscope(OM), scanning electron microscope(SEM), energy disperse spectroscopy(EDS), X-ray Diffraction(XRD) hardness tester and friction wear testing machine. The results show that the original WC particles were dissolved greatly under the action of high-energy laser beam. The phase of coating is mainly composed of carbides WC, W2C,(Cr, Fe)7C3, W6C and Fe-Cr solid solution. The microstructure of WC/Co50 coating is complex, which consists of the primary dendrites, cellular eutectic, interdendritic eutectic and hard phase particles. The average hardness of the WC/Co50 coating is 1.93 times of the substrate, and the hardness of WC/Co50 cladding coating decreases with the increase of the surface depth. Under the same conditions, the wear weight loss of the composite coating is only 13.3% of the substrate.