某奥氏体不锈钢法兰在使用过程中颈部出现开裂渗漏现象，通过材料化学成分分析、金相显微组织分析、扫描电镜观察裂纹断面微观形貌及X射线能谱分析裂纹断面腐蚀产物成分，对法兰开裂原因进行了分析。结果表明：法兰材料碳元素含量超标，且存在热加工缺陷，晶界处有大量析出物，法兰使用过程中存在拉应力及腐蚀环境，以上因素共同作用导致法兰颈部发生沿晶应力腐蚀开裂。

Cracking and leakage phenomenon occurred at the neck of an austenitic stainless steel flange during operation. Through detecting the material chemical compositions, analyzing the microstructure, observing the cracking fracture surface with scanning electron microscopy and analyzing the corrosion products with X-ray energy dispersive spectrometer, the cracking causes of the flange were analyzed. The results show that the carbon content of the flange material exceeded the standard requirement, and there were a large number of precipitates at the grain boundary due to the heat treatment defects. At the same time, the flange suffered tensile stress and corrosive environment during operation. The above factors together caused the intergranular stress corrosion cracking at the neck of the flange.