10CrMo910钢管蒸汽侧氧化膜的形态特征

摘要

Steam-side oxidation scales formed on inner surface of super-heater and re-heater tubes made of 10CrMo910 steel in a power plant were investigated by metallurgic inspection,scanning electron microscope-energy dispersive X-ray (SEM-EDX) spectrometer,and X-ray diffraction analysis.Results show that the steam-side oxidation scale normally consists of two layers:the inner layer is a heterogeneous oxidation film rich in Cr and pores,whereas the outer layer contains porous and fine particles identified as Fe3O4 and Fe2 O3 ; internal oxidation exists at the interface between base metal and inner layer,resulting in compact bonding of the interface; the oxidation at interface between inner and outer layer is not obvious,where firm adhesion is formed and a small number of oxide particles are left after decomposition; both the inner and outer oxidation layer are composed of nanometer or micro particles,and the thermal stress caused by mismatch of thermal expansion coefficients are relaxed by pores lying in the oxidation particles.The steam-side oxidation film of 10CrMo910 steel tube is difficult to peel,and its growing thickness may cause the heating surface steel tube to work at overheating temperatures.%对某电厂锅炉过热器和再热器受热面10CrMo910钢管蒸汽侧氧化膜进行了金相、扫描电镜、能谱和X衍射等试验分析,研究了蒸汽侧氧化膜的形态特征及其形成规律.结果表明:蒸汽侧10CrMo910钢管氧化膜分为内、外2层,内层为富含孔洞的富Cr层的非均质氧化膜,外层为疏松而细小的Fe3O4和Fe2O3；金属基体与内层氧化膜的界面处存在内氧化,使界面结合紧密；内层与外层氧化层界面不明显,离解后的氧化物颗粒较少,界面黏附强度较高,且内、外层氧化膜均由纳米和微米级颗粒组成,由于热膨胀系数不同导致应力大部分由氧化颗粒间空隙吸收；10CrMo910钢管蒸汽侧氧化膜难以剥落,且增厚的氧化膜容易导致受热面钢管长期处于过热状态.