某发电机组的锅炉水冷壁自投入使用以来，多次发生过热管穿孔失效事故。采用宏观观察、化学成分分析、拉伸性能试验、硬度测试、金相检验等方法对过热管的穿孔失效原因进行分析。结果表明：失效过热管长期处于450 ℃以上的高温状态，局部区域管壁温度达到600 ℃，使过热管长期承受高温及氧化腐蚀作用，过热管的珠光体组织发生明显球化，局部完全球化，沿晶界存在较多游离渗碳体，显微组织的恶化使过热管的强度和力学性能下降；被腐蚀减薄的过热管在管内压力作用下膨胀变形，最终导致过热管穿孔失效。

Since the water wall of a generator set was put into use, the superheat pipe perforation failure accidents occurred many times. The perforation failure causes of superheat pipe were analyzed by means of macroscopic observation, chemical composition analysis, tensile property test, hardness test and metallographic examination. The results show that the failure superheat pipe was in the high temperature state above 450 ℃ for a long time, and the local wall temperature reached 600 ℃, which made the superheat pipe endured high temperature and oxidation corrosion for a long time. The pearlite structure of the superheat pipe was obviously spheroidized and partially completely spheroidized, and there were more free cementite along the grain boundary. The deterioration of the microstructure made the strength and mechanical properties of the superheat pipe decrease. The corroded and thinned superheat pipe expanded and deformed under the action of pressure in the pipe, which eventually led to the perforation failure of the superheat pipe.