超高速激光熔覆镍基合金涂层组织性能及抗高温冲蚀性能

To solve the fly-ash erosion damage of the heating surface in thermal power boiler, nickel-based alloy coating with excellent high temperature erosion resistance was prepared on the surface of 15CrMo steel pipe by ultrahigh speed laser cladding technology. The microstructures of the coating were analyzed by SEM, EDS, EBSD and so on, and the mechanical properties and high temperature erosion resistance of the coating were further studied. The results show that the coating have thinner thickness (215 μm) and low surface roughness (14.56 μm), and there is no obvious crack inside the coating and at the interface. The coating is mainly composed of γ-Ni dendrites and intergranular Laves phases, and from the coating interface to the surface, γ-Ni grains gradually transform from the planar crystal morphologies near the interface of the coating to the equiaxed crystal morphologies near the surface of the coating. The average hardness of the coating is about 328.07HV, which is about 1.8 times that of 15CrMo steel. The average shear strength at the interface between the coating and the substrate is 414.26 MPa, which proves that the coating has good metallurgical bonding characteristics. The coating showed better resistance to solid particle erosion at 600 ℃, and the volume loss of erosion was about 63% less than that of substrate. This is mainly attributed to its high hardness and high temperature oxidation resistance.