Microstructure and Properties of WC-Cr₇C₃ Composite ReinforcedIron-Based Laser Cladding Layer

Taking chromium powder, tungsten powder, graphite powder and iron powder as cladding layer raw materials, and Ni60 alloy powder as bonding layer raw material, WC-Cr₇C₃ composite reinforced iron-based cladding layer was prepared on the surface of 45 steel substrate by laser cladding technique. The macroscopic morphology of the cladding layer under different laser power (2 500-3 500 W) and scanning speed (2-5 mm·s^-1) was studied to determine the optimal process parameters, and the microstructure and properties of the cladding layer under the optimal process were analyzed. The results show that the optimal laser cladding process parameters were the laser power of 3 500 W and the scanning speed of 2 mm·s^-1. The WC-Cr₇C₃ composite carbides with network structure were in situ spontaneously generated in the cladding layer. From the surface to the interior of the cladding layer, the microstructure gradually changed from equiaxed and dendrite to columnar and plane crystal. The average hardness of the cladding layer was 507.6 HV, which was about 63.8% higher than that of the matrix. The average stable friction coefficient was 0.128, which was only one forth of the matrix, and the wear rate was 4.9×10⁵ cm³·N^-1·m^-1, which was only one ninth of the matrix; the wear form was slight abrasive wear and slight adhesive wear.