摘要
采用金相检验、扫描电镜分析及力学性能试验等方法,对一种长期服役后的锅炉过热器弯头开展材料性能研究,并对其开裂失效的原因进行分析。结果表明,过热器弯头试样的化学成分、布氏硬度及冲击功均符合相关标准要求;金相组织正常,均为铁素体加珠光体,球化等级为2级,属于轻微球化。过热器弯头发生开裂的主要原因是管道背弧面内壁存在超标直道缺陷。该缺陷处引起应力集中,诱发裂纹萌生,同时管道内壁腐蚀坑及裂纹内部氧化物、碳化物的形成加速了裂纹的扩展,导致弯头背弧面处发生开裂泄漏。
The material properties of a boiler superheater elbow that has been in long-term service are studied by means of metallographic examination,scanning electron microscopy analysis and mechanical property tests,and the causes of its cracking and failure are analyzed.The results show that the chemical composition,Brinell hardness and impact energy of the superheater elbow specimens all meet the relevant standard requirements.The metallographic structure is normal,all consisting of ferrite and pearlite,with a spheroidization grade of 2,which belongs to mild spheroidization.The main reason for the cracking of the superheater elbow is the existence of excessive straight passage defects on the inner wall of the back arc surface of the pipe.This defect causes stress concentration,inducing crack initiation.Meanwhile,the corrosion pits on the inner wall of the pipe and the formation of oxides and carbides inside the crack accelerate the crack propagation,leading to cracking and leakage at the back arc surface of the elbow.
作者
焦占坡
蒋志龙
邱伟明
雷鹏
石玮
许辉
JIAO Zhanpo;JIANG Zhilong;QIU Weiming;LEI Peng;SHI Wei;XU Hui
出处
《节能》
2025年第9期131-134,共4页
Energy Conservation
基金
中国华电集团有限公司科技项目(项目编号:CHDKJ24-04-02-04)。
关键词
过热器弯头
裂纹
直道缺陷
应力集中
superheater elbows
cracks
straight path defect
stress concentration
