核电厂海水泵用镀锌高强度螺栓的开裂原因  

Cracking Reasons of Zinc Coated High-Strength Bolt for Seawater Pump in Nuclear Power Plan

作　　者：张彦召[1] 张舟永[1] 刘洪群[1] 刘忠[1] ZHANG Yanzhao;ZHANG Zhouyong;LIU Hongqun;LIU Zhong(Suzhou Nuclear Power Research Institute,Suzhou 215004,China)

机构地区：[1]苏州热工研究院有限公司,苏州215004

出　　处：《腐蚀与防护》2024年第8期99-102,113,共5页Corrosion & Protection

摘　　要：某核电厂海水泵用双头镀锌高强度螺栓发生开裂失效。通过材料性能(化学成分、显微组织和力学性能等)检测及断口和裂纹形貌观察,分析了螺栓的失效原因。结果表明:镀锌螺栓开裂的原因为氢致开裂。锌镀层破损的高强度螺栓与海水接触时,表面锌镀层和螺栓基体形成电偶对,基体作为阴极析出氢,部分原子氢扩散进入螺栓基体导致氢致损伤,螺栓在预紧力的持续作用下发生氢致开裂。A double-headed zinc coated high-strength bolt in a seawater pump of nuclear power plant cracked.The failure reasons of the bolt were analyzed through testing of material properties(chemical composition,microstructure and mechanical properties)and morphology observation of fracture and cracks.The results show that the failure of the high-strength bolt was the result of hydrogen induced cracking(HIC).When the high-strength bolt with damaged zinc coating was in contact with seawater,a galvanic couple formed between the surface zinc coating and the bolt substrate,and the substrate worked as cathode on which hydrogen was precipitated.Some atomic hydrogen diffused into the bolt substrate,resulting in hydrogen damage.HIC happened on the bolt under the continuous action of preloading force.

关 键 词：镀锌 高强螺栓 沿晶开裂 氢致开裂 电偶对 

分 类 号：TM623.7[电气工程—电力系统及自动化]