Investigation on Microstructure and Mechanical Properties of WC Particle Reinforced Ni-based Composite layers

Effect of cladding power on the microstructure and properties of the layers was systematically investigated to resolve the problem of delamination and decomposition during the preparation of the composite layers. WC particle and Ni-based alloy composite powders were employed to fabricate the reinforced Ni-based composite layers by laser cladding technology on 34MnB5 steel.The microstructures and phase composition of powders and layers were characterized using OM, SEM, XRD, and EDS. Layers thickness and WC volume fraction were measured with Image J software, while hardness and tribological properties were evaluated via microhardness testing and ASTM G65 standard wear experiments.The results show that the hardness and surface morphology of composite layers significantly is improved with increasing cladding power, however, WC volume fraction in layers was decreased from 41.6% to 30.2%. When the cladding power is high, the overheating will lead to the decomposition of WC particles to form free C and W atoms, which will be dissolved into the Ni-based matrix or formed W-rich carbides lead to the hardness elevating of matrix.Tribological properties testing show that wear resistance is positively correlated with the volume fraction of WC particles under low-stress abrasion condition. So, wear resistance of composite layers is preferred when the cladding power is 1.4 kW. However, when the cladding power is 1.8 kW, there is almost no cracks and higher surface quality, which is suitable for applications on the balancing condition of surface qualities and impact resistance.