长期服役后末级再热器12Cr1MoVG钢管的组织性能和剩余寿命评估

Microstructure,Performance and Remaining Life Assessment of 12Cr1MoVG Steel Pipe of Final Reheater after Long Service

利用光学显微镜、扫描电镜、能谱仪、维氏硬度计等仪器,对服役1×10^(5)h后某火电机组末级再热器12Cr1MoVG钢管进行组织分析、力学性能测试和剩余寿命评估。结果表明:该钢管的化学成分、力学性能均符合标准要求;钢管处于应力安全状态;钢管珠光体球化级别为3~4级,合金元素产生了明显的再分配现象,固溶合金元素贫化明显;未见蠕变孔洞,蠕变处于稳定的第二阶段;根据氧化膜厚度计算得到的管壁当量温度超过额定蒸汽温度,存在超温现象,但是未超过12Cr1MoVG钢的最高使用温度;根据氧化膜厚度估算的该钢管的剩余使用寿命超过100000 h。

Using optical microscope,scanning electron microscope,energy spectrometer,Vickers hardness tester and other equipment,the microstructure analysis,performance test and remaining life assessment of the 12 Cr1 MoVG steel pipe of final reheater of a thermal power unit after 1×10^(5)h service were carried out.The results showed that chemical compositions and mechanical properties of steel pipe met standard requirements,and steel pipe were in a stress safe state.Steel pipe pearlite spheroidization level was 3-4,the alloying elements had produced obvious redistribution phenomenon,and the solid solution alloying elements are obviously depleted.No creep holes were observed,and the creep was in a stable second stage,the equivalent temperature of pipe wall calculated based on oxide scale thickness exceeded the rated steam temperature.There was an over-temperature phenomenon,but it did not exceed the maximum service temperature of 12 Cr1 MoVG steel.The remaining service life of steel pipe estimated based on oxide film thickness exceeded 100000 h.