Abstract: The failure mechanism of an austenitic stainless steel boiler tube under high temperature and hydrogen environment was investigated by optical and scanning electron microscope. Mechanical properties of the boiler tube were also studied by tensile, impact and hardness tests. The results show that high-temperature creep-fatigue cracking is the major reason for the failure of this component. From the morphology of view, the cracks initiate in a mixed mode and propagated in a typical intergranular way. High temperature stainless steel tubes in the boiler are subjected to high thermal stress during frequent starting and shutting down, causing fatigue and creep interaction in the material, and eventually leading to the final failure. 

Key words: High temperature environment, Creep, Austenitic stainless steels, Failure analysis

摘要： 采用金相显微镜、扫描电镜以及拉伸、冲击、显微硬度测试等检测手段，对高温临氢环境下开裂的奥氏体不锈钢锅炉管进行失效原因分析。分析结果表明，奥氏体不锈钢高温锅炉管断裂为典型的疲劳-蠕变断裂模式，裂纹形态为穿晶沿晶混合萌生、沿晶扩展。高温不锈钢炉管在运行过程中承受较大的热应力，在锅炉频繁起停过程中应力不断循环变化，导致构件承受疲劳与蠕变交互作用并最终使奥氏体不锈钢锅炉管开裂。

关键词: 高温环境 , 蠕变 , 奥氏体不锈钢 , 失效分析