Applicability of a Deterministic Approach to Transfer the Fracture Toughness J_c Between Different Specimen Thicknesses

In this paper, validity of the deterministic approach to transfer the fracture toughness J_c obtained with different thickness specimens was demonstrated. For this purpose, applicability of the (4δ_t, σ_22c) failure criterion [1] was verified to transfer J_cs obtained for different specimen thicknesses in the fracture toughness database obtained from decommissioned Shoreham reactor vessel steel [2, 3]. The material tested was ASTM A533 Grade B Class 1 ferritic steel tested in the ductile-to-brittle transition temperature region. The critical value σ_22c for twelve types of specimens (thickness in the range of 8 to 254 mm) showed only 4% variation. The fact that these critical values were always reached at the specimen mid-plane and the fact that cleavage always initiated at the specimen mid-plane supported the validity of the deterministic approach. Because the (4δ_t, σ_22c) failure criterion requires only “single” set of test data for J_c transfer and because σ_22c shows only a few % scatter, it seems to have a possibility to replace what Weibull stress is expected to do.