Abstract
To satisfy the additional surveillance test requirements for the extension of operating period of the nuclear reactor, the upper-shelf fracture toughness evaluation using a miniature C(T) (Mini-C(T)) specimen which has a thickness of 4 mm is desired to be established for direct evaluation of fracture toughness with less consumption of the precious surveillance specimens, in addition to the Master Curve method to evaluate the fracture toughness in ductile-brittle transition temperature. For testing Mini-C(T) specimens, compared to External Load-Line Displacement (ELLD) measurement, Front Face Displacement (FFD) measurement has the advantage of a larger displacement and better robustness in case of excessive displacement to be accidently applied. This study was aimed to examine the applicability of FFD measurement for the JIc test on Mini-C(T) specimen. The JIc tests were performed on Mini-C(T) specimens made of Japanese RPV steels SFVQ1A and SQV2A at room temperature. ELLD and FFD were simultaneously measured during the test using two clip gauges. As a result, the rotation center of Mini-C(T) specimens during the JIc test ranged from 28% to 58% of the ligament length from the crack tip. The ratio of ELLD to FFD decreased monotonically as the crack propagated and ranged from 0.71 to 0.76. The conversion coefficient of FFD to ELLD as 0.73 and 0.75 are both within the range obtained by the present study. The resistance curves based on the FFD multiplied by 0.73 or 0.75 demonstrated good consistency with that based on ELLD with the difference less than 5% of J-integral values.
Published Version
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