某电站上充泵马氏体不锈钢转轴在化学清洗后表面出现局部腐蚀，为了查明局部腐蚀发生的原因，开展了现场检查和模拟试验。结果表明：在操作不当的情况下，马氏体不锈钢的表面易发生缝隙腐蚀；在模拟酸性溶液中，马氏体不锈钢的自腐蚀电位远远低于奥氏体不锈钢的，存在严重的电偶腐蚀倾向。在缝隙腐蚀和电偶腐蚀的共同作用下，马氏体不锈钢的泵轴出现了局部腐蚀。

Localized corrosion was found on the rotation shaft of a charging pump after decontamination. In order to find the reason of localized corrosion, examination of charging pump and simulation experiment were carried out. The results showed that crevice corrosion happened on martensitic stainless steel when the decotanmination process was taken inappropriately. The self corrosion potential of martensitic stainless steel was lower than that of austnitic stainless steel, which could accelerate the corrosion rate of the shaft due to galvanic corrosion. The corrosion reason of the shaft was due the co-effect of crevice corrosion and galvanic corrosion.