核电主管道取样管焊缝疲劳开裂案例分析.pdf

装备环境工程 第13卷 第2期 ·98 · EQUIPMENT ENVIRONMENTAL ENGINEERING 2016年4月 核电主管道取样管焊缝疲劳开裂案例分析 梁夏香，段远刚 （中广核工程有限公司设计院核岛设备所，广东 深圳 518124） 摘要：目的 针对某核电机组主管道取样管焊缝水压试验后渗透检测时发现的超标线性显示，分析 失效原因，探讨制造期间不常见的疲劳裂纹形成及扩展的机制，分析导致疲劳的交变应力源所 在。方法 通过宏观分析、金相观察、断口扫描电镜试验。结果 材质未见异常，该线性显示为裂纹 所致，是疲劳裂纹。结论 取样管焊缝焊趾部位多源裂纹不是水压试验所产生的，为水压试验后机 械加工去除堵头时，因切削不良使取样管侧焊趾附近承载的交变载荷过量引起的疲劳开裂；疲劳 应力主要来自水压试验后取样管堵头切除加工工序，铣削不良是引发疲劳裂纹的关键因素。 关键词：核电主管道；水压试验；焊趾；疲劳裂纹 DOI ：10.7643/issn.1672-9242.2016.02.018 中图分类号：TJ91 文献标识码：A 文章编号：1672－9242（2016）02－0098-05 Case Analysis of Fatigue Cracking on the Weld of Sampling Connection of Main Coolant Lines LIANGXia-xiang ，DUANYuan-gang （China Nuclear Power Engineering Co. ，Ltd ，NI Equipment Design Dept ，Shenzhen 518124 ，China） ABSTRACT ：Objective According to unacceptable linear indications by liquid penetrant examination on the weld of sampling connection of main coolant lines after hydrostatic test during manufacturing, the failure causes were analyzed, the formation and propagation mechanism for rarely seen fatigue cracks during manufacturing was explored, and the alternating stress source of fatigue was discussed. Methods In the paper, macroscopic analysis, optical microscope and scanning electron microscope were used. Results The results showed that the material quality was acceptable and the linear indication was caused by fatigue cracks. Conclusion The multi-source crack in the weld toe of the sampling pipe was not caused by hydrostatic test, but was fatigue cracking resulted from the excessive alternating current l