某电站锅炉末级再热器对接焊缝泄漏故障论析

Analysis of the Leakage Fault of Butt Weld of the Last Reheater of a Power Station Boiler

通过宏观检查、化学成分、硬度检测、力学性能、金相等试验手段分析某电站锅炉末级再热器对接焊缝泄露原因。分析结果表明,该末级再热器对接焊缝沿T91段熔合线处断裂,T91段金相组织为回火马氏体组织,老化等级3级,管段存在一定程度的超温。得出该对接焊缝开裂原因为蠕变断裂,其蠕变产生与超温运行及管子承受相关应力密切相关的结论。

Through the macro inspection,chemical composition,hardness testing,mechanical properties,and gold equivalent test methods,the cause of leakage of the butt welding seam of the last reheater of a power plant boiler is analyzed.The results show that the last-stage reheater breaks along the fusion line of T91 segment,the metallographic structure of T91 segment is tempered martensite and the aging level is 3,which means the certain degree of over-temperature in the pipe segment.The cracking of butt weld is caused by creep fracture,and it′s related to the over-temperature operation and the stress on the pipe.