摘要
过热器是提高发电锅炉循环热效率的关键部件,其部件一旦失效会造成巨大的经济损失。通过力学性能测试、微观形貌及成分能谱分析、 X射线衍射物相分析及金相分析等方法,对ASH低温过热器受热面管焊接接头的断裂原因进行了分析。结果表明:该焊接接头的断裂形式为高温疲劳和应力腐蚀共同作用后的断裂,应力腐蚀所产生的点蚀是造成裂纹启裂的原因,断口形貌具有碱性断裂的特征,同时结合锅炉水pH值8.57和腐蚀产物分析,该断口为碱性腐蚀断裂。采用有限元分析软件ABAQUS对受热面管在运行过程中的应力分布进行了模拟,验证了其在运行过程中焊接接头位置应力集中的存在。为了防止碱脆断裂,应对锅炉用水进行充分软化处理,同时管道焊接应控制焊缝成形,提高焊接质量,焊后进行去应力退火处理。
Superheater is a key component to improve the thermal efficiency of power generation boilers. Once broken, it will cause huge economic losses. The fracture causes of the welded joint of ASH low temperature superheater heating surface pipes were analyzed by mechanical properties test, micromorphology and compositional energy spectrum analysis, X-ray diffraction phase analysis and metallographic analysis. The results showed that the fracture form of the welded joint was the joint of high temperature fatigue and stress corrosion. The pitting corrosion caused by stress corrosion was the cause of crack initiation. The fracture morphology had the characteristics of alkaline fracture.Combined with the analysis of p H value 8.57 of the water and corrosion products, the fracture was alkaline corrosion fracture. The stress distribution during the operation of the heating surface pipe was simulated by the finite element analysis software ABAQUS, and the existence of stress concentration in the position of welded joint during operation was verified. In order to prevent the alkaline fracture, the boiler water should be fully softened, at the same time,the weld forming and the quality of the welding joint should be controlled, and the stress removal annealing treatment should be carried out after welding.
作者
李厚一
范玲玲
唐国
周友龙
LI Hou-yi;FAN Ling-ling;TANG Guo;ZHOU You-long(School of Materials Science and Engineering,Southwest Jiaotong University,Chengdu 610036,Sichuan pro.,China)
出处
《焊接技术》
2020年第5期109-114,I0012,共7页
Welding Technology
关键词
失效分析
应力腐蚀
高温疲劳
点蚀
有限元模拟
failure analysis
stress corrosion
high temperature fatigue
pitting
finite element simulation
