粉末冶金材料科学与工程
粉末冶金材料科學與工程
분말야금재료과학여공정
POWDER METALLURGY MATERIALS SCIENCE AND ENGINEERING
2014年
1期
159-164
,共6页
FCo-5钴基合金粉末%核阀密封面%激光熔覆层%组织%硬度
FCo-5鈷基閤金粉末%覈閥密封麵%激光鎔覆層%組織%硬度
FCo-5고기합금분말%핵벌밀봉면%격광용복층%조직%경도
FCo-5 cobalt-base alloy powder%nuclear valve sealing surface%laser cladding layer%microstructure%hardness
以FCo-5自熔性钴基合金粉末为堆焊材料，在0Cr18Ni12Mo3Ti核阀试样表面制备厚度为2.04 mm、横截面单圆弧拟合半径为2.69 mm的密封面激光熔覆层。利用SEM和XRD分析熔覆层的微观结构和物相，测试熔覆层的显微硬度及最小厚度处的高温硬度。结果表明：熔覆层从界面到表层的结晶形态依次由平面晶向胞状树枝晶、多方向生长树枝晶、细小树枝晶过渡；中、上部组织主要由γ-Co 奥氏体枝晶、枝晶间层片状共晶组织以及弥散分布的Cr23C6硬质颗粒组成；在距界面1.52~1.60 mm的区域，密封带宽度为2.95～3.18 mm，常温硬度阈值为44.3～45 HRC；在650℃以下时，熔覆层最小厚度处具有优异的抗蠕变性能和高温硬度特性，经720℃以上回火处理后有较强的二次硬化效应。
以FCo-5自鎔性鈷基閤金粉末為堆銲材料，在0Cr18Ni12Mo3Ti覈閥試樣錶麵製備厚度為2.04 mm、橫截麵單圓弧擬閤半徑為2.69 mm的密封麵激光鎔覆層。利用SEM和XRD分析鎔覆層的微觀結構和物相，測試鎔覆層的顯微硬度及最小厚度處的高溫硬度。結果錶明：鎔覆層從界麵到錶層的結晶形態依次由平麵晶嚮胞狀樹枝晶、多方嚮生長樹枝晶、細小樹枝晶過渡；中、上部組織主要由γ-Co 奧氏體枝晶、枝晶間層片狀共晶組織以及瀰散分佈的Cr23C6硬質顆粒組成；在距界麵1.52~1.60 mm的區域，密封帶寬度為2.95～3.18 mm，常溫硬度閾值為44.3～45 HRC；在650℃以下時，鎔覆層最小厚度處具有優異的抗蠕變性能和高溫硬度特性，經720℃以上迴火處理後有較彊的二次硬化效應。
이FCo-5자용성고기합금분말위퇴한재료，재0Cr18Ni12Mo3Ti핵벌시양표면제비후도위2.04 mm、횡절면단원호의합반경위2.69 mm적밀봉면격광용복층。이용SEM화XRD분석용복층적미관결구화물상，측시용복층적현미경도급최소후도처적고온경도。결과표명：용복층종계면도표층적결정형태의차유평면정향포상수지정、다방향생장수지정、세소수지정과도；중、상부조직주요유γ-Co 오씨체지정、지정간층편상공정조직이급미산분포적Cr23C6경질과립조성；재거계면1.52~1.60 mm적구역，밀봉대관도위2.95～3.18 mm，상온경도역치위44.3～45 HRC；재650℃이하시，용복층최소후도처구유우이적항연변성능화고온경도특성，경720℃이상회화처리후유교강적이차경화효응。
A sealing surface laser cladding layer with thickness of 2.04 mm and cross section of circular arc having a fitting radius of 2.69 mm was prepared on a 0Cr18Ni12Mo3Ti nuclear valve sample surface using FCo-5 fluxed cobalt-base alloy powder as overlaying welding material. The microstructure and phase composition of the cladding layer were analyzed using SEM and XRD. The microhardness of the cladding layer and high temperature hardness at the position with minimum thickness were measured. The results show that the crystal morphology of coating altered in turn as plane crystal cellular dendrites, multi-directional growth dendrites and fine dendrites from the interface to surface. The mid and upper microstructure mainly consists of γ-Co austenite dendrite, interdendritic layer lamellar eutectic organization and dispersed Cr23C6 hard particle phase. The seal belt width varies from 2.95 mm to 3.18 mm, hardness threshold under normal temperature is 44.3~45 HRC in the region away from the interface 1.52~1.60 mm. The minimum thickness localized cladding layer has the characteristic of good creep resistance and high temperature hardness below 650℃, as well as can generate strong secondary hardening effect after tempering above 720℃.
