Additional Investigations on the Applicability of Miniature Compact Tension Specimens for Fracture Toughness Measurements in the Upper Shelf Regime

The use of small-size or even miniaturized mechanical specimens is nowadays quite popular, due to the fact that it allows optimizing material consumption, especially when material availability is an issue or when space inside irradiation facilities is limited. In 2004, we assessed the applicability of the miniature Compact Tension specimen (MC(T), with cross section 10 × 10 mm² and thickness = 4.15 mm) for elastic-plastic fracture toughness measurements in the fully ductile regime. Additional investigations were however recommended in order to clarify several aspects of the methodology, namely: - behaviour of MC(T) and 1TC(T) specimens in the crack tip blunting phase; - effective limit for the measuring capacity of different specimen geometries; - role of work hardening in decreasing tearing resistance; - comparison between MC(T) and 1TC(T) specimen for a very low toughness material; - use of alternative parameters (CTOD, CTOA, JM) for characterizing fracture toughness instead of the J-integral. Detailed results for these complementary investigations are provided in this report. Additionally, empirical correlations between critical values measured from MC(T) and 1TC(T) specimens have been obtained, which allow estimating ductile crack initiation within ±35% at the 95% confidence level.