动态载荷下奥氏体不锈钢管道LBB环向贯穿裂纹稳定性实验及理论分析方法研究

管道环向贯穿裂纹是否稳定是评判管道是否满足破前漏（LBB）设计准则的标准之一，为确保LBB技术安全可靠，对管道环向贯穿裂纹在动态载荷下的稳定性进行实验研究。采用水平冲击机对含环向贯穿裂纹的管道依次进行加载速度为1.22、2、3、4 m/s的高温不带运行压力的冲击实验，以获得各应变率下的实验极限载荷值，并与工程理论分析计算结果进行比较。分析表明:奥氏体不锈钢管道环向贯穿裂纹在动态载荷下的失效模式为塑性失稳；经实验验证，在工程中对承受动态载荷的奥氏体不锈钢管道进行LBB分析时，采用美国核管会标准审查大纲3.6.3破前漏评估程序（SRP 3.6.3）中的极限载荷理论分析方法具有较高的工程安全性，若同时选用准静态下的材料力学性能，则工程安全性更高。 

Research on Test and Theoretical Analysis Methods on Stability of LBB Circumferential Through-Wall Crack in Austenitic Stainless Steel Pipe under Dynamic Load

Judging whether the circumferential through-wall crack of pipe is stable is one of the criteria to judge whether the pipe meets the Leak-Before-Break (LBB) design criteria. In order to ensure the safety and reliability of LBB technology, the stability of circumferential through-wall crack of pipe under dynamic load is studied and analyzed by experiment. The horizontal impact machine was used to carry out the impact test on the pipe with circumferential through-wall crack without operating pressure at high temperature with the loading speed of 1.22 m/s, 2 m/s, 3 m/s, 4 m/s in order to obtain the test limit load values at each strain rate, and then compared with the engineering theoretical analysis and calculation results. The results show that the failure mode of circumferential through-wall cracks in austenitic stainless steel pipe under dynamic load is plastic instability. Through the verification of the test, when LBB analysis is carried out for austenitic stainless steel pipe under dynamic load in the project, the theoretical analysis method of limit load in the standard review plan 3.6.3 leak-before-break evaluation procedures (SRP 3.6.3) of the NRC has high engineering safety. If the mechanical properties of materials under quasi-static state are adopted at the same time, the engineering safety is higher.