摘要
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 appearance, structure, composition and phase of the oxidefilms of the high-temperature reheater pipe made of 12Cr1 MoVsteel after running under high-temperature and high-pressure wa-ter vapor for 5.0×104 hours were analyzed by means of scanningelectron microscopy, electron probe microanalysis, and X-raydiffraction. Results indicate that the oxide films have varied ap-pearances depending on locations. Namely, buninoid-like ormushroom-like oxide films were formed at the locations in contactwith water vapor, bulk oxide film was calcite -like, and the cross-section of the oxide film appeared as rock-candy fracture. At thesame time, the oxide films can be divided into three classes interms of the structure, including the outer layer, the middle lay-er, and the inner layer all composed of rough cylindrical grains.A large number of pores were formed between adjacent-cylindricalgrain layers, while the grains in the middle and bulk oxide layersappeared as fine equiaxed grains. From the outer layer to bulk ox-ide films, a positive concentration gradient of oxygen was ob-served, while a negative concentration gradient of alloying ele-ments Fe. Cr and Mo was observed. Moreover: elements Cr andMo were enriched in the bulk oxide film in contact with the steelsubstrate, showing a higher content than in the steel substrate.And the oxide films are composed of Fe3O4 and FeCr2O4.
出处
《材料保护》
CAS
CSCD
北大核心
2009年第11期66-68,共3页
Materials Protection
