海水泵泵轴失效原因的研究

某电厂4#海水泵断续工作33个月后,泵轴产生局部腐蚀。本文根据材质、浸泡和腐蚀疲劳等试验结果,预测了泵轴的腐蚀和可能发生失效的过程是:泵轴局部表面镀铬层脱落,镀层下的3Cr13钢发生晶间腐蚀,并导致孔蚀。由于存在闭塞条件和电偶电流,加速局部腐蚀。蚀坑底部萌生晶间裂纹、裂纹扩展,直至发生腐蚀疲劳断裂。

Study on Failure Cause of the Pump Shaft Working in Seawater

The local corrosions on the pump shaft surface had been occurred after working for 33 months in seawater.From the experiment results of quality analysis,properties testing,immersion corrosion and corrosion fatigue of the 3Cr13 steel cutting from the pump shaft working in corrosion environment of seawater,the processes predicted about corrosion and failure were followed.Due to the slough off the local chromium coating from the pump shaft surface,intergranular corrosion and pitting under the coating were generated.Because of existence of block condition and couple current,the local corrosion rate was increased.The intergranular cracks were initiated at the pit bottom,which caused the cracks propagation and corrosion fatigue at the last.