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对锅炉再热器管进行宏观检查、化学成分分析、金相显微组织观察和力学性能测试,分析了锅炉再热器管的失效原因。结果表明:该锅炉二级再热器管由于超温运行,因过热引起管子弯头的内外壁产生较厚的氧化皮。管子外弧面壁厚不足并在高温作用下使该处管子发生局部鼓胀,致使氧化皮开裂,露出的基体金属继续被氧化,管子内表面不断氧化与膨胀,导致锅炉二级再热器管破裂。
The macro inspection, chemical composition analysis, metallographic microstructure observation and mechanical property test of the boiler reheater tube were carried out. The causes of the failure of the boiler reheater tube were analyzed. The results show that the second reheater tube of the boiler runs over-temperature, causing thick oxide scales on the inner and outer walls of the pipe elbow due to overheating. The outer wall of the pipe is not thick enough and under the action of high temperature, local bulging of the pipe occurs. As a result, the scale cracks and the exposed base metal continues to be oxidized, and the inner surface of the pipe continuously oxidizes and expands, resulting in the rupture of the secondary reheater tube of the boiler.