某核电站凝汽器密封结构用镍铝青铜螺栓断裂原因  

Causes of fracture of Ni-Al bronze bolt used in the condenser seal structure of a nuclear power station

作　　者：高腾飞 郭凯 李心刚 翟新年 罗真 GAO Tengfei;GUO Kai;LI Xingang;ZHAI Xinnian;LUO Zhen(Daya Bay Nuclear Power Operations and Management Co.,Ltd.,Shenzhen 518000,China;China Nuclear Shenzhen Kelly Nuclear Energy Service Co.,Ltd.,Shenzhen 518000,China)

机构地区：[1]大亚湾核电运营管理有限责任公司,深圳518000 [2]中核深圳凯利核能服务有限公司,深圳518000

出　　处：《理化检验（物理分册）》2023年第11期32-34,37,共4页Physical Testing and Chemical Analysis(Part A:Physical Testing)

摘　　要：某核电站凝汽器密封结构用镍铝青铜螺栓发生断裂现象,采用宏观观察、化学成分分析、扫描电镜分析、力学性能测试、金相检验等方法对螺栓断裂的原因进行分析。结果表明:螺栓在潮湿的NH3环境下发生了应力腐蚀开裂;断裂螺栓在服役过程中受到不均匀的应力载荷,使表面应力腐蚀倾向变大,且螺栓长期处于自身应力腐蚀敏感介质中,在二者的耦合作用下,应力腐蚀裂纹萌生;裂纹沿残余应力较高的相界区域向内扩展,最终导致螺栓发生断裂。The Ni-Al bronze bolt used for the sealing structure of a certain nuclear power plant condenser fractured.The causes of bolt fracture were analyzed by macroscopic observation,chemical composition analysis,scanning electron microscopy analysis,mechanical property testing and metallographic examination.The results show that the bolts experienced stress corrosion cracking in a humid NH,environment.During service,fractured bolts were subjected to uneven stress loads,resulted in an increased tendency for surface stress corrosion.Moreover,the bolts were exposed to their own stress corrosion sensitive medium for a long time.Under the coupling effect of the two,stress corrosion cracks initiated on the bolts.The crack propagated inward along the phase boundary area with high residual stress,ultimately led to bolt fracture.

关 键 词：镍铝青铜 螺栓 应力腐蚀断裂 腐蚀敏感介质 

分 类 号：TB31[一般工业技术—材料科学与工程] TG115.2[金属学及工艺—物理冶金]