抄録
The X-ray fractography was applied to the full thickness, ESSO specimens made of a 250mm thick steel for nuclear reactor presssure vessels SA533B Cl. 1 to study the phenomena of brittle crack propagation and arrest.
The stress intensity factor KIdyn obtained through the half value breadth of the X-ray diffraction intensity curve from the fracture surface increased strongly as the crack propagated except in the very early stage in which KIdyn decreased significantly. It had an upper limit around the half of the crack propagation length before the first arrest, decreased thereafter and then gradually increased with oscillations until the crack was finally arrested.
While the crack propagated at a nearly constant velocity, KIdyn increased monotonically. When the crack velocity decreased sharply, the increase in KIdyn discontinued and oscillations started.
The relation between the stress intensity factor at crack arrest KIdyn (Arrest) and temperature did not depend upon the testing method. The stress intensity factor at crack arrest Kca which was obtained by the static analysis of the ESSO test tended to underestimate the crack arrest toughness.
