某电厂300 MW锅炉高温过热器管在进行水压试验时发生开裂，采用宏观观察、化学成分分析、金相检验、硬度测试、拉伸试验、微观分析、X射线能谱分析等方法，对高温过热器管的开裂原因进行了分析。结果表明：该高温过热器管内壁存在明显的脱碳层和腐蚀坑。脱碳层使得管子耐腐蚀能力降低，并且弯管和焊接处存在残余应力，两者共同作用导致管子发生应力腐蚀直至开裂。

The high temperature superheater tubes of a 300 MW boiler in a power plant cracked during hydraulic test. By means of macro observation, chemical composition analysis, metallographic examination, hardness test, tensile test, micro analysis, X-ray energy spectrum analysis and so on, the cracking causes of high temperature superheater tubes were analyzed. The results show that there were obvious decarbonization layer and corrosion pits on the inner wall of the high temperature superheater tubes. The decarbonization layer reduced the corrosion resistance of the tubes, and the residual stress existed in the elbow and the weld. The combined action of the two resulted in stress corrosion of the tubes until cracking.