某1 000 MW核电机组检修期间发现，汽轮机联轴器螺柱表面出现不同程度的损伤。采用宏观和微观形貌观察、力学性能测试、金相检验、扫描电镜观察、化学成分和能谱分析，对螺柱表面损伤的原因进行了分析。结果表明：螺柱表面损伤的类型属于点腐蚀损伤；引起点腐蚀损伤的原因为螺柱服役环境中存在腐蚀性元素，尤其是活性阴离子氯。

During the period of maintenance of a 1 000 MW nuclear power unit, damage with different degree appeared on the surface of coupling studs of the steam turbine. The causes of the surface damage of the studs were analyzed by methods of macro and micro morphology observation, mechanical property testing, metallographic examination, scanning electron microscope observation, chemical composition and energy spectrum analysis. The results show that:the type of the surface damage of the studs was the pitting corrosion damage; the cause of pitting corrosion damage for studs was that corrosive elements existed in the service environment of the studs, especially the reactive anionic Cl^-.