Volume 26, Issue 4 (July 1998)
A Procedure for Fracture Toughness Testing Using a Chevron-Notched Crack-Arrest Specimen
A new chevron-notched crack-arrest (CNCA) specimen has been developed for determining the fracture toughness of metals in a more cost-effective manner. The specimen is a hybrid design that incorporates features from the standard KIc and KIc specimens. Details of the specimen geometry and associated test procedures are described. Strain gages record the stress state in the specimen, and a clip gage measures the crack mouth opening displacement. The method for extracting arrest and initiation toughness from the measured data is presented. Fracture experiments using the CNCA specimen ware conducted to determine Ka and Kc for A533-B reactor grade steel at 23°C. The Ka and Kc results from this study were consistent with similar data established for the same material by other-researchers. A fractographic analysis identified cleavage as the dominant failure mode during crack propagation, with a conversion to ductile tearing just before arrest.