Effect of WC morphology on microstructure and properties of stellite 6/WC composite layer by laser cladding

In order to enhance the wear resistance of 45 steel, a WC/Stellite 6 composite layer with 30% WC which with different morphologies (spherical and irregular) was prepared on the surface of 45 steel by laser cladding technology. The effects of WC morphology on the phase composition, microstructure, microhardness, and wear resistance of the cladding layer were compared and analyzed. The results show that the surface of the cladding layer was well formed. M₂₃C₆, M₇C₃, WC, and W₂C exist in both cladding layers. With the addition of spherical WC, the diffraction peaks of γ-Co appear on the left side of the main peak of Co₆W₆C. The area of intergranular carbides accounts for a large proportion in the surface layer which with the fine grains. During the process of laser cladding the spherical WC particles with loose structure easy to melt include particle inside. However, the melting amount of irregular WC particles is finite, which only occurs on the periphery of the particles, and the inside of the particles is relatively complete. The microhardness of two cladding layers gradient increases from the substrate to the surface layer. The surface layer added spherical WC has higher microhardness, which reaching 790.6 HV₁. Nevertheless, the wear resistance of the cladding layer added irregular WC is better than that of the cladding layer added spherical WC. The reason is because that the incompletely melted irregular WC particles uniformly distributed in the cladding layer which provided the support points for the cladding layer matrix during the wear process, the wear of the cladding layer by the grinding pair reduced consequently.