某锅炉在运行期间发生水冷壁管泄漏事故，检查发现数十根管材外壁存在横向裂纹。通过宏观检查、化学成分分析、力学性能测试、金相检验和扫描电镜分析，对锅炉水冷壁管横向裂纹的形成原因进行了分析。结果表明：在壁温波动导致的热疲劳应力和腐蚀气氛的共同作用下，锅炉水冷壁管向火侧管壁发生了腐蚀疲劳开裂，形成了密集的横向裂纹，最终导致水冷壁管泄漏。

The leakage of water wall tubes occurred during the operation of a boiler. It was found that there were transversal cracks on the outer wall of dozens of tubes. The formation cause of the transversal cracks of the water wall tubes in the boiler were analyzed by means of macroscopic examination, chemical composition analysis, mechanical property test, metallographic examination, SEM analysis and so on. The results show that under the combined action of the thermal fatigue stress caused by the tube wall temperature fluctuation and the corrosion atmosphere, the boiler water wall tubes suffered corrosion fatigue on the fire side of the tube, which resulted in dense transversal cracks and eventually led to leakage of the water wall tubes.