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电厂的12Cr2MoWVTiB钢高温再热器管实际运行中易出现氧化失效,为了对其实施有效的监督,采用扫描电镜、电子探针和X射线衍射对高温高压水蒸气下运行5.0×104h形成的氧化膜形貌、结构、成分及物相进行了分析。结果表明:氧化膜蒸汽侧形貌呈丘状或蘑菇云状,氧化膜基体侧呈方解石状,氧化膜横断面呈石状;氧化膜结构明显分为3层,外层、中间层和内层氧化膜均由粗大的柱状晶构成,各柱状晶层间有大量孔洞,而内层氧化膜与基体结合处氧化膜晶粒为细小等轴晶;O元素含量从外层氧化膜到靠近基体处,存在正的浓度梯度分布,而Fe,Cr,Mo元素含量存在负的浓度梯度分布,Cr,Mo元素在紧靠基体的氧化膜侧产生富集,含量均高于钢基体中的含量;氧化膜物相为Fe3O4和FeCr2O4。
The 12Cr2MoWVTiB steel high temperature reheater tube in power plant is prone to oxidation failure in practical operation. In order to supervise it effectively, the oxide film formed by 5.0 × 104h under high temperature and high pressure steam is analyzed by scanning electron microscope, electron probe and X-ray diffraction Morphology, structure, composition and phase were analyzed. The results showed that the steam-side morphology of the oxide film was mound or mushroom cloud, the substrate side of the oxide film was calcite, and the cross-section of the oxide film was stone. The oxide film structure was obviously divided into three layers, the outer layer, the middle layer and the inner layer were oxidized The film is composed of coarse columnar crystals, a large number of holes between the columnar crystal layer, and the oxide film on the inner oxide film and the substrate is fine equiaxed grain; O element content from the outer oxide film to close to the matrix, There is a positive concentration gradient distribution, while there is a negative concentration gradient distribution of the Fe, Cr and Mo elements. The Cr and Mo elements are enriched in the oxide film close to the matrix, and the content is higher than that in the steel matrix. The oxide film The phase is Fe3O4 and FeCr2O4.