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针对国内核电站再热双阀组阀杆表面乙炔气堆焊Co Cr W制备耐磨焊层无法满足60年服役寿命要求的问题,在阀杆材料(304不锈钢)表面激光熔覆Ni60/石墨/Mo S2复合涂层。采用X射线衍射(XRD)、扫描电镜(SEM)和显微硬度检测等技术研究了熔覆层组织结构、相组成、显微硬度。结果表明,试样C2熔覆层从底部到顶部,熔覆层晶体依次为:平面晶、胞状晶、胞-树枝状晶、柱状树枝晶、等轴树枝晶,且平均硬度最高,为990 HV0.3。随着激光功率的升高,各类熔覆层硬度的波动幅度逐渐减小,硬质相的分布也随之越来越均匀。
Aiming at the problem of 60-year service life requirement for the wear-resistant welding layer made of Co Cr W on acetylene gas surface at the valve stem surface of the reheating double-valve group of nuclear power station in China, the surface of valve stem material (304 stainless steel) is laser cladded with Ni60 / graphite / Mo S2 composite coating. The microstructure, phase composition and microhardness of the coating were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and microhardness testing. The results show that the cladding layer from the bottom to the top of the sample C2, followed by the cladding crystal: flat crystal, cell crystal, cell - dendrites, columnar dendrites, equiaxed dendrites, and the highest average hardness of 990 HV0 .3. With the increase of the laser power, the fluctuation of the hardness of all kinds of cladding gradually decreases and the distribution of the hard phase becomes more and more uniform.