某油田海水管线的C70600材质变径接头发生了腐蚀穿孔现象。通过宏观观察、化学成分分析、电镜及能谱分析、XRD分析，以及电化学测试等理化检验手段，对失效样件进行了检测。结果表明，由于流速突变和湍流存在造成的流场诱导腐蚀使管壁发生腐蚀穿孔。建议对于流速大于2.4 m/s的部位，在设计中应改进流道结构，降低流速，防止或减轻流场的突变。

Corrosion perforation of a reducer union occurred in a seawater pipeline whose material was C70600. Through material analysis, SEM, EDS, XRD and electrochemical test, the failure sample's performance was tested. The results showed that the reason of corrosion perforation was flow induced corrosion caused by velocity mutation and turbulent flow. It was suggested that the user should change the flow passage in design and reduce the velocity to prevent flow or decrease flow mutation for the position whose velocity was over 2.4 m/s.