Fracture Toughness Behavior and Its Analysis on Nuclear Pressure Vessel Steels

Abstract

A drop weight J_Id testing machine has been developed successfully, by which the multiple specimen J resistance curve test technique can be applied to measure the fracture toughness. In this study, the use of a small size round compact tension (RCT) specimen for measuring the fracture toughness J_Ic or J_Id of the nuclear pressure vessel steels is recommended and confirmed for the surveillance tests.
The static and dynamic fracture toughness of ASTM A508 C 1.2, A508 C 1.3 and A533 Cr.B C 1.1 steels in the wide range of temperature including the upper shelf have been measured and their behavior has been analysed. The fracture toughness behavior under various strain rates and in a wide temperature range can be explained by the behavior of stretched zone formation preceding the crack initiation. The scatter of K_J values in the transition range is caused by the amount of crack extension contained in the specimens. In this paper, the method to obtain the fracture toughness equivalent to the K_Ic from the K_J value is also presented.