【摘要】 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。更多还原

【Abstract】 Based on the consideration that the reheat double valve stem with Co Cr W coating by acetylene gas welding used in nuclear power plant failures to meet the requiments of 60-year service time,compose layers of Ni60 / graphite / Mo S2 on the 304 stainless steel stem surface were prepared by laser cladding using different formulation of the alloy powders. Microstructure,phase composition and microhardness of the clad layers were studied by means of X-ray diffraction( XRD),scanning electron microscopy( SEM) and microhardness test. The results show that there are flat crystal,cellular dendrite,columnar dendrites and equiaxed dendrites successively distributed from bottom to top of sample C2,and the average hardness of the sample C2 reaches the maximum value of about 990 HV0. 3. As the laser power increases,the fluctuation range of the hardness of the clad coating gets smaller and the distribution of hard phases is more uniform.更多还原