Effect of overlap rates on forming quality and properties of laser cladding Ni40A-WC composite coatings

Abstract To investigate the effect of the overlap rates on quality, microstructure and mechanical properties of the cladding layer, the Ni40A-WC composite coating on the surface of H13 steel was prepared by laser cladding technology, and the surface morphology, crack defects, microstructure, microhardness, friction and wear of composite coatings with different overlap rates was detailed characterized and analyzed. The results show that the overlap rates is a key parameter that affects the quality and performance of coatings, and Ni40A-WC coating with flat surface, compact structure and significantly improved mechanical properties can be obtained by appropriate overlap rates. With the increase of the overlap rates, the WC particles in the coating increased, the hard phase diffraction peak intensity of Cr7C3, W2C and Cr23C6 in the microstructure increased, and the microhardness and wear resistance also increased. The mean hardness of the coating at 50%, 60%, 70% and 80% overlap rates increases 1.01, 1.16, 1.17 and 1.71 times of the hardness of H13 substrate, respectively, and the wear rate decreases by about 57%, 65%, 74% and 83%, respectively.