锅炉F-A异种钢接头早期失效统计分析及防控措施

应用于超(超)临界机组的电站锅炉受热面的铁素体钢-奥氏体钢(F-A)异种钢接头经常发生断裂,断裂形式以铁素体钢侧熔合线开裂为主。对江苏省内超(超)临界锅炉F-A异种钢接头失效情况及检验结果进行了统计分析,发现F-A异种钢接头倾向于在低等级材料、薄壁管、较大附加弯矩、复杂管屏、焊缝根部存在焊瘤等情况下发生失效;且接头失效由熔合界面的氧化、蠕变及疲劳3种机制所支配。并进一步针对影响接头失效的关键可控因素提出了防控措施。

Statistical Analysis of Early Failure of Boiler F-A Dissimilar Steel Joint and Preventive Measures

Ferritic steel-austenitic steel(F-A)dissimilar steel joint of heating surface of utility boiler used in ultra supercritical unit often breaks,the main fracture mode is the side fusion line cracking of ferrite steel.In this paper,the failure and inspection results of F-A dissimilar steel joints of ultra supercritical boilers in Jiangsu Province are statistically analyzed.It is found that F-A dissimilar steel joints tend to lose in the case of low grade material,thin-walled pipe,large additional bending moment,complex pipe screen and weld bead at the root,and the joint failure is dominated by oxidation,creep and fatigue of the fusion interface.Furthermore,the prevention and control measures for the key controllable factors affecting joint failure are proposed.