Abstract
CTOD has been calculated using the plastic hinge model with an assumed rotational center since the British Standard Institution standardized BS5762 in 1979. The American Society for Testing and Materials, ASTM, accepted the plastic hinge model and standardized E1290 in 1989. However, ASTM revised E1290 in 2002, and has proposed a conversion from J-integral to CTOD. Another CTOD test standard, ASTM E1820, was also revised in 2005 according to the conversion from J-integral to CTOD.
CTOD-based fracture toughness evaluation has been widely used for the defect assessment of a lot of welded structural components, and two different calculations of CTOD could lead to confusion for Fitness-for-Service. The Japan Welding Engineering Society has organized a working group in order to investigate the effects of CTOD testing methodology on CTOD values. In the working group, CTOD round robin tests were conducted using more than 40 kinds of rolled steels for welded structure, and the difference between the critical CTOD values obtained by ASTM E1290:2002 and those by BS7448, which involves the plastic hinge model, was discussed. In the present report, the results of the CTOD round robin tests were referred to, and a concept of CTOD as a fracture parameter was described.
