摘要
某电站锅炉水冷壁管在运行过程中发生数次泄漏,利用化学成分分析、显微组织观察、硬度检测等方法对泄漏原因进行了分析。结果表明:失效管段化学成分、硬度满足标准要求,显微组织为铁素体+珠光体,珠光体轻度球化。泄漏点位于同一根管的多处横向裂纹处,裂纹起裂于向火侧内壁中部位置的螺旋附近。水冷壁管内壁存在垢层,炉水在氧化铁垢下方和螺旋的缝隙内发生介质浓缩,该处溶解氧和介质浓度急剧增加,产生电化学腐蚀。向火侧管壁承受较大的交变热应力,在热疲劳载荷作用下,在内壁腐蚀缺陷处起裂扩展,裂纹经过疲劳和腐蚀的共同作用,发生泄漏。
The water-cooled wall pipe of a boiler in a power station leaked several times during the operation.The reasons for the leakage were analyzed by chemical composition analysis,microstructure observation,hardness testing and other methods.The results showed that the chemical composition and hardness of the failed pipe met the standard requirements,the microstructure was ferrite+pearlite,and the pearlite was slightly spheroidized.The leak points were located at multiple transverse cracks in the same pipe,and the cracks started near the spiral at the middle of the inner wall on the fire side.There was a scale layer on the inner wall of the water wall,and the furnace water was concentrated under the iron oxide scale and in the spiral gap,where the dissolved oxygen and the medium concentration increased sharply,resulting in electrochemical corrosion.The pipe wall on the fire side beared a large alternating thermal stress,and under the action of thermal fatigue load,cracks expanded at the corrosion defects of the inner wall,and the cracks passed through the combined action of fatigue and corrosion until they leaked.
作者
谌康
蔡文河
杜双明
董树青
高大伟
杨志博
李旌鑫
SHEN Kang;CAI Wenhe;DU Shuangming;DONG Shuqing;GAO Dawei;YANG Zhibo;LI Jingxin(Institute of Thermal Power Technology,China Datang Corparation Science and Technology Institute,Beijing 100040,China;Institute for Special Steels,Central Iron and Steel Research Institute,Beijing 100081,China)
出处
《腐蚀与防护》
CAS
北大核心
2022年第2期62-67,共6页
Corrosion & Protection
关键词
水冷壁管
腐蚀
介质富集
疲劳
water cooled wall
corrosion
medium enrichment
fatigue
