600MW超临界锅炉TP347H高温过热器管爆管的显微分析

Microscopic Analysis on Tube Explosion of TP347H High Temperature Superheater Pipe for 600MW Supercritical Boiler

对爆管相关资料和数据进行了调查。借助微机控制电子万能实验机、金相显微镜、扫描电镜及能谱仪等仪器设备,从爆管管样、未胀粗管管样和备用管样的拉伸性能、显微组织、晶粒度、第二相等方面对TP347H高温过热器管的爆管原因进行了分析。结果表明:TP347H高过管爆管为高温蠕变失效。TP347H奥氏体不锈钢在长期高温运行过程中于晶界处析出了σ相,且细小的晶粒度促进了σ相在晶界的析出。σ相的析出和大量存在,导致了蠕变孔洞的出现,使得TP347H高过管材质快速老化,导致高温蠕变强度下降,直至爆管。

The related information and data of tube explosion were investigated.The reasons for tube explosion of TP347 H high temperature superheater pipe were analyzed by computer control electronic universal testing machine,optical microscope,scanning electron microscope and energy dispersive spectrdmeter from the aspect of tensile property,microstructure,grain size,second phase of exploded tube sample,non-bulging tube sample and spare tube sample.The results show that the tube explosion of TP347 H high temperature superheater pipe belongs high temperature creep failure.σphase precipitates at the grain boundary of TP347 H austenitic stainless steel in the process of long-term high temperature operation.The fine grain size is beneficial to the precipitation ofσpha s e.The precipitation and high content ofσpromote the appearance of creep holes at a prolonged high temperature runing.It can accelerate the aging of TP347 H and lead to a decline in high temperature creep strength,and then,the tube explodes.