Theoretical and experimental study on unstable fracture for type 304 stainless steel plates with a soft tensile testing machine

The structural materials used for the LWR piping system are mainly stainless steels of Type 304, 316 or similar ones. Because of the very high toughness of these materials, unstable fracture can be usually excluded as a failure mode, and so the leak-bef ore-break concept is generally accepted as a design basis for the LWR piping made of the above materials. However, there have been questions about the fact that the leak-before-break concept can still be established for the LWR piping with very soft loading condition, which may be close to a dead load condition and regarded to be very severe from the point of view of the stability of crack extension. In the actual LWR piping, this kind of loading is deeply related to the length of pipe compared with its other dimensions and also to the character of internal pressure.