Abstract
In order to study an effect of loading rate on fracture toughness of steels for pressure vessels, static and dynamic fracture toughness tests and brittle crack arrest test were carried out. The steels used were two kinds of nuclear pressure vessel steel, A508 Cl.3 and A533B Cl.1, and an Al-killed steel.
The results obtained are as follows:
(1) The plane-strain fracture toughness was independent of the increase rate of stress intensity factor, K.
(2) The values of plane-strain fracture toughness obtained by static and dynamic fracture toughness tests and brittle crack arrest test were the same.
(3) Fracture toughness became lower as K increased in the transition region in which plastic deformation cannot be ignored.
(4) The fracture toughness during brittle crack propagation, KID, became higher as the crack propagation rate increased, owing to the rise of temperature caused by the fracture of material near the crack tip.
