Study On The Microstructure And Properties Of WC/Ni Laser Cladding Coatings

In recent years, the technology of preparing laser-cladding WC/Ni composite coating on the metal substrate surface has attracted more and more attention. Among them, how to effectively combine high toughness of the nickel-based materials with wear resistance of WC reinforced phase has great significance. At present work, with Q345 R steel being the substrate, Ni alloy powder and WC/Ni composite cladding layer were prepared on its surface by laser cladding technology. The surface morphology, organization, composition, phase composition and hardness values, etc.of the cladding layer were inxestigated by using of optical microscopy, scanning electron microscopy(SEM), its accessory EDS, and hardness. The results show that as the power increases, the organization of both single-path and multi-path cladding layer of Ni alloy powder are small and compact, without obvious defects. When the laser power ranges from 2500 W to 3500 W, the longitudinal average microhardness values of Ni-based alloys’ single-path cladding layer respectively are 320.4HV, 318.2 HV and 311.4 HV, and its horizontal average microhardness values respectively are 326.7HV, 306.9HV, 311 HV. The longitudinal average microhardness values of multi-path cladding layer respectively are 318.1 HV, 322.9HV, 315.8HV, and its horizontal average microhardness values are 315.2HV, 312.9HV, 313.9HV.This indicates that the hardness values of whether single-path or multi-path of Ni base alloy laser cladding layer changes little, and its distribution is more homogeneous. In WC/Ni composite coating, when the single-path and multi-path cladding layers are added to 20% WC content, the overall performance of the cladding layer is good. And as WC content increases, the organization of cladding layer will become smaller and smaller. When the WC content respectively is 10%、20%、30%、40%、50%, the average microhardness values of WC/Ni single-path cladding layer respectively are 383.6HV, 501.1HV, 505.3HV, 524.9HV, 535.8HV, and the average microhardness values of multi-path cladding average respectively are 379.7 HV, 501.2 HV, 552.6 HV, 624 HV, 622.5 HV, indicating that with increasing WC content, the average hardness values of single-path and multi-path cladding layer are tended to continue to increase, but when the WC content reaches 30%, whether single-pathl or multi-path cladding layer appears holes, cracks and other defects.Therefore, the WC content should be controlled within 20%.