锅炉对流管胀管接头开裂失效分析

通过宏观检验、化学成分分析、扫描电镜断口分析、金相检验以及力学性能测试等方法,对某糖厂锅炉对流管胀管接头的开裂失效原因进行了分析。结果表明:对流管胀管接头开裂主要是由于锅炉在频繁快速启、停过程中,悬吊下锅筒的对流管反复膨胀、回复,导致对流管在受应力集中及弯曲应力作用最大的胀管接头处产生热疲劳裂纹,裂纹沿晶扩展导致胀管接头脆性开裂。

Failure Analysis on Cracking of Expansion Pipe Joints of Convection Pipes of a Boiler

The cracking failure cause of expansion pipe joints of convection pipes of a sugar refinery＇s boiler was analyzed through macroscopic examination, chemical compositions analysis, SEM fracture analysis, metallographic examination and mechanical properties test. The results show that inflation and recovery repeatedly of convection pipes which suspending water drum, during the frequently quick startup and stop process of the boiler, led to the expansion pipe joints fatigue cracking by the role of largest stress concentration and the bending stress, and the cracks development led to the brittle cracking along the grain boundary.