Comparative Study on Fatigue Crack Growth Performance of Nuclear Stainless Steel Weld Joints and Base Metal

Welded joints are widely used on the pipe sockets in nuclear power plants, and fatigue cracks are one of the important causes resulting in the failure of welded joints. Therefore, it is of great significance to study the fatigue crack propagation and life prediction methods for welding zone materials to accurately predict the life of welded joints. This paper takes the commonly used 304L stainless steel weld material in nuclear power plants as the object to study the effects of different load ratios and different sampling directions on the fatigue crack growth rate. Based on the test data, the fatigue crack growth rate model of the weld material is established, and it is compared with the austenite steel in ASME standard. The results show that different sampling directions have little effect on the fatigue crack growth rate of the weld, but the load ratio has a greater impact on it. At a lower load ratio, the fatigue crack growth rate of the weld is higher than that of the base metal before a certain ?K value, and thereafter it is lower than that of the base metal thereafter, but vise versa with higher load ratios.