某锅炉过热器管在运行约1 a(年)后发生爆裂。对爆裂管进行了断口宏观及微观分析、化学成分分析、硬度测试和金相检验, 以分析其爆裂原因。结果表明: 该锅炉过热器管长时间处于高温高压的运行条件下, 管件内表面产生了较厚的氧化皮, 导致局部管壁温度升高; 过热器管显微组织严重劣化, 粗大的碳化物颗粒析出并在晶界富集长大, 导致晶界弱化; 晶界处出现裂纹并不断扩展, 最终导致管件爆裂。

A super-heater tube of one boiler burst after operating for one year. The bursting reasons of the super-heater tube were analyzed by fracture macroscopic and microscopic analysis, chemical composition analysis, hardness testing and metallographic analysis. The results show that: the super-heater tube was in operation under the high temperature and high pressure condition for a long time, and the thick oxide scale was generated on the inner wall of the tube which caused the temperature of local tube wall rose; the microstructure of the super-heater tube aged seriously, and the coarse carbide particles precipitated, gathered and grew up in grain boundaries, which weakened the grain boundaries; cracks appeared and extended along the grain boundaries constantly, and finally caused the bursting of the super-heater tube.