T91钢高温水蒸汽氧化层形成机理研究

Mechanism of the Formation of the Oxidation Layers of T91 Steel Tube Under the High Temperature Water Vapour

为了研究T91钢高温高压水蒸汽条件下锅炉管道内壁氧化层的形成机理 ,对T91钢锅炉再热器管内壁高温高压水蒸汽条件下的氧化层形貌进行观察 ,利用X Ray物相分析仪测试氧化层的物相结构。结果表明 :T91钢在高温高压水蒸汽环境下产生的氧化皮内层为极薄且含有大量阳离子空位的单相无晶界CrFe2 O4(阳离子空位约为 3 7% )非晶体结构 :中层为较厚的单相CrFe2 O4细等轴晶和在其上生长的粗柱状晶结构 :外层为Fe3 O4 Fe2 O3

In order to research the mechanism of the formation of the oxidation layers of T91 steel under the high temperature water vapour,the profile morphololgies of rust scale of the inner wall of T91 boiler re-heater was observed by the optical microscope and scanning electron microscope,and the phase structure of the oxide layer was also analyzed by X-ray diffraction.The results showed that under high-temperature and high-pressure water vapour the inner oxide layer of T91 steel tube is the very thin layer of CrFe_2O_4(which contains 37% cation vacanies),which is a single-phase,non-grain boundary and non-crystal microstructure;The medial layer is the thick,single-phase layer CrFe_2O_4 which consists of the lower fine equiaxed crystal structure and the upper coarse columnar crystal microstructure;the outer layer is Fe_3O_4-Fe_2O_3 which consists of the lower tine equiased crystal and the upper coarse columnar crystal microstructure.