Microstructure and Mechanical Properties of Millimeter WC Particle-Reinforced High-Chromium Cast Iron Composites

WC particle/HCCI composites were prepared using liquid-phase sintering technology. In this study, millimeter WC particles were used to ensure that minimal WC particle performance was compromised during the preparation process. Moreover, with the aim of controlling the evolution of microstructures and secondary carbide precipitation in the matrix, different heat treatment methods were adopted in the manufacturing process. The microstructures of the composites were investigated via SEM, XRD, EPMA and TEM. The results showed that perfect metallurgical bonding was formed between the LCS and the WC/HCCI composites, and the width of the diffusion layer was 120 to 129 µm after heat treatment. A large number of secondary carbides precipitated in the matrix during heat treatment, and martensite formation occurred in the matrix during the subsequent cooling process, which effectively increased the microhardness of the matrix. The impact toughness of the LCS-toughened composites after heat treatment was 1.6 times that of the WC/HCCI composites, and the shear strength was 5 times that of the as-cast composites. The wear resistance of the composites under quenching at 950 °C and tempering at 220 °C was 5 times that of the as-cast composites.