某电厂锅炉用12Cr1MoVG钢过热器管在使用约17 520 h后发生爆管, 为找到爆管的原因, 对其进了失效分析。结果表明: 该钢管长期在高温环境下服役, 基体组织发生了珠光体球化, 导致钢管的强度降低; 在高温蒸汽环境下, 钢管内壁易生成氧化皮, 氧化皮的脱落、再生过程循环往复, 导致钢管厚度减薄, 强度降低; 以上两者共同作用使得钢管的强度下降明显; 由于蒸汽中含有腐蚀性元素, 导致钢管内壁产生腐蚀凹坑, 这些凹坑处会产生应力集中, 在高温下, 当应力集中程度超过钢管的强度后, 就发生了爆管。

After operation about 17 520 h, 12Cr1MoVG steel superheater tube used in a boiler of a power station cracked. In order to find the burst causes, failure analysis was carried out. The results show that the pearlite in the matrix turned to spheroidization because the tube used at high temperature over a long period of time, which resulted in the decrease of strength of the tube. Under the environment of high temperature vapor, the oxide scale was easily formed on the inner wall of the tube and then broken off because of vapor washing. Circularly, the thickness of the tube was reduced further and the strength significantly decreased at the two combined action. Corrosion pits were found on inner wall of the tube pits because of the corrosive elements in the vapor, and then, the corrosion pits became crack source as a result of stress concentration. If the stress concentration exceeded the strength of the steel tube at high temperature, the tube would burst.