TP347H钢高温过热器内壁氧化皮失效分析  

Failure Analysis of TP347H High Temperature Superheater Tube's Oxide Layer

作　　者：张山山 ZHANG Shan-shan(Huadian Electric Power Research Institute ,Hangzhou 310030,China)

机构地区：[1]华电电力科学研究院,浙江杭州310030

出　　处：《发电与空调》2017年第3期18-22,共5页

摘　　要：对TP347H钢锅炉高温过热器的氧化皮保护性能进行失效分析,研究氧化皮的形成、剥落机理。利用扫描电镜观察管样内壁氧化皮的微观结构和形貌特点,利用能谱分析仪测试分析内壁氧化皮合金元素的浓度变化。研究表明:氧化皮的形成机理主要是蒸汽氧化机理和氧气氧化机理两种,当管材中含有足量的合金元素Cr,保证其在正常的内外扩散条件下,形成并保持Fe-Cr尖晶石,甚至完整的Cr_2O_3富铬层的保护性氧化皮。氧化皮结构的破坏以及剥落主要是由于氧气过氧化机理,当蒸汽环境中含有过量的溶氧时,溶氧作为强氧化剂,与Fe-Cr尖晶石、Cr_2O_3富铬层发生过氧化反应,破坏了Fe-Cr尖晶石、Cr_2O_3富铬层的结构和组成,使其丧失了保护作用。氧化皮形成、剥落的模型主要依据蒸汽氧化机理、氧气氧化机理和氧气过氧化机理,3种机理解释了氧化皮形成、生长和剥落的全过程。The protective properties of the oxide layer of TP347H high temperature superheater tube were analyzed in this study. The formation and exfoliation mechanism of the oxide layer was researched. The microstructure of the oxide layer of TP347H high temperature superheater tube was observed by scanning electron microscope（SEM） and the morphological features of it was also analyzed. The concentrations of alloy elements in the section of internal tube were quantitatively analyzed using energy dispersive system（EDS）. The results showed that：The formation mechanism of oxide layer were mainly steam oxidation mechanism and oxygen oxidation mechanism. When the pipe had enough content Cr,to ensure the normal internal and external diffusion conditions,and the Fe-Cr spinel was formed,even the protective layer of Cr_2O_3 was formed. The oxide skin damage and exfoliation is mainly due to the oxygen oxidation mechanism. When the steam environment containing excess oxygen,dissolved oxygen as oxidant and it happened oxygen reaction with Fe-Cr spinel and Cr_2O_3 chromium layer. That destroy the structure and composition of Fe-Cr spinel,Cr_2O_3 chromium layer,so that the oxide layer loss of protective effect. The formation and exfoliation of oxide scale is mainly based on the mechanism of steam oxidation,the mechanism of oxygen oxidation and the mechanism of oxygen oxidation. The three mechanisms explain the whole process of the formation,growth and exfoliation of oxide skin.

关 键 词：TP347H钢 高温过热器 氧化皮 蒸汽氧化 氧气氧化 氧气过氧化 机理研究 

分 类 号：TM621.2[电气工程—电力系统及自动化]