核阀密封面激光熔覆无钨低碳中钴合金粉末

Laser cladding of tungsten-free low carbon moderate cobalt alloy powder on nuclear valve sealing surface

在0Cr18Ni12Mo3Ti不锈钢核阀试样表面进行了FCo-5合金粉末的单道激光熔覆。研究了熔覆层的显微组织特征、相结构,并讨论了与显微硬度的对应关系。试验结果表明:具有无钨低碳中钴特点的FCo-5合金粉末激光熔覆层与基体达到了良好的冶金结合;熔覆层组织主要为γ-Co奥氏体枝晶、枝晶间大量共晶组织及原位生成的Cr23C6颗粒相;熔覆层横截面显微硬度曲线呈"类M型"分布,最低硬度值较基体提高了192 HV0.2以上;弥散分布的Cr23C6颗粒对提高密封面的耐磨性非常有利。FCo-5合金粉末熔敷金属符合核阀密封面堆焊材料的技术要求,可以替代高钴含量的Stellite合金,并有益于减少二次污染、降低核阀成本。

Single-channel laser cladding of FCo-5 alloy powder was carried out on 0Cr18Ni12Mo3Ti stainless steel nuclear valve specimen surface. The characteristics of microstrueture and phase structure of the clad layer were investigated, and a corresponding relationship with the microhardness was also discussed. The experimental results show that the laser clad layer of FCo-5 alloy powder with tungsten-free low carbon moderate cobalt characteristics has achieved a good metallurgical bond with the substrate. Microstructure of the clad layer is mainly composed of γ-Co austenite dendrites, a large number of interdendritic eutectic structure and Cr23C6 particle phase in situ. The microhardness profile of the clad layer is a “like M-type” distribution, the minimum hardness value is enhanced by 192 HV0.2 than that of the substrate ; The dispersed Cr23 C6 particles is very favorable to improve the wear resistance of the sealing surface. The FCo-5 alloy powder deposited metal conform to the technical requirements of the surfacing materials for nuclear valve sealing surface, which can replace the Stellite alloys with high cobalt content, and also reduce secondary pollution and the cost of nuclear valves.