The X-ray fractography was applied to the compact and ESSO specimens of pressure vessel steels for nuclear reactors to evaluate the dynamic fracture toughness KID during brittle crack propagation. The relation between KID and the crack velocity was studied.
In the compact specimen, KID decreased as the crack propagated and its value at crack arrest was equal to KIa but smaller than KIm. The steady crack velocity in the compact specimen at-60°C was about 550m/sec, at which KID was almost equal to KIm. The relation between the steady crack velocity and the arrested crack length was similar to the experimental and analytical results obtained previously on DCB specimens.
The dynamic fracture toughness during the crack propagation became greater with an increase in both crack velocity and temperature, while it was independent of the test method.
