12Cr1MoVG高温过热器爆管失效分析  

Failure analysis of tube bursting of 12Cr1MoVG high temperature superheater

作　　者：金敏华 刘献良 赖云亭[2] 朱保印 JIN Minhua;LIU Xianliang;LAI Yunting

机构地区：[1]江苏常熟发电有限公司,江苏苏州215536 [2]苏州热工研究院有限公司,江苏苏州215004

出　　处：《电力科技与环保》2021年第5期42-45,共4页Electric Power Technology and Environmental Protection

基　　金：国家重点研发计划“超期服役承压设备寿命预测及延寿关键技术研究”(2016YFC0801905)。

摘　　要：针对某火力发电厂运行13万h的12Cr1MoVG高温过热器管爆管的问题,对爆口管及相邻管取样进行了宏观检验、化学成分分析、力学性能测试及金相组织检验等试验分析,得出了过热器管爆管的原因。爆口管及相邻管弯头、弯头附近的进口侧及出口侧,显微组织均为铁素体+碳化物,珠光体球化级别已达5级,组织严重老化。管子内壁氧化皮厚度较大,其中,爆口管出口侧、相邻管出口侧和相邻管弯头的内壁氧化皮厚度分别已达548μm、516μm和583μm。根据管子内壁氧化皮厚度与运行温度的关系及氧化皮厚度测量数据,参考DL/T654-2009计算的爆口管出口侧、相邻管弯头的当量金属壁温分别已达582℃和585℃,超过了12Cr1MoVG的最高允许服役温度580℃,存在超温运行的情况。结合失效管段爆口边缘减薄量较小、爆口断面粗糙等特征,得出了管段爆管的主要原因为管段长时间超温运行,导致材料显微组织和力学性能显著劣化,最终引起强度不足而爆管。爆口出现一定的塑性变形,与管子爆破前出现了一定的短时超温有关,短时超温加速了爆管的发生。根据上述分析结论,从管段剩余寿命评估、氧化皮厚度定期监测、严格控制金属壁温等方面,提出了相应的预防措施。Aiming at the bursting problem of the 12Cr1MoVG high temperature superheater tube in a thermal power plant serving for 130000 hours,the macroscopic inspection,chemical composition analysis,mechanical performance test and metallographic inspection of the burst tube and adjacent tube were carried out.The reason for the tube burst of the superheater tube is obtained.The microstructure of the elbow and the inlet side and outlet side near the elbow of the bursting tube and the adjacenttube are all the same with ferrite and carbide,the pearlite spheroidization level has reached level 5,and the structure is seriously aging.The oxide scale thickness of the inner wall of the tubes are relatively large,and the thickness of the outlet side of the blasting tube,the outlet side of the adjacent tube and the adjacent tube elbow has reached 548μm,516μm and 583μm respectively.The thickness of the oxide scale on the inner wall of the tube is relatively large.According to the relationship between the thickness of the inner wall of the tube and the service temperature and the measurement data of the thickness of the oxide,the equivalent metal wall temperature of the outlet side of the blasting tube and the adjacent tube elbow calculated with reference to DL/T654-2009 has reached 582℃and 585℃,respectively,exceeding the maximum allowable service temperature of 580℃of 12Cr1MoVG.This shows that the tube has been overheating servicing.Combining with the characteristics of small thinning at the edge of the blast hole and rough section of the blast hole,it is finally concluded that the main reason for the tube burst is the prolonged overheating service,which leads to significant deterioration of the microstructure and mechanical properties,and finally caused insufficient strength.The certain plastic deformation of the blast hole is related to the certain short-term overtemperature before the blasting of the tube.The short-term overtemperature accelerated the occurrence of the tube burst.Corresponding preventive measures are propos

关 键 词：12CR1MOVG 过热器管 当量温度 长时过热 

分 类 号：TK229.6[动力工程及工程热物理—动力机械及工程]