Application of T33-Stress to Predict the Lower Bound Fracture Toughness for Increasing the Test Specimen Thickness in the Transition Temperature Region

Abstract

This work was motivated by the fact that although fracture toughness of a material in the ductile-to-brittle transition temperature region Jc exhibits the test specimen thickness (TST) effect on Jc, frequently described as Jc∝(TST)-1/2, experiences a contradiction that is deduced from this empirical formulation; that is, Jc = 0 for large TST. On the other hand, our previous works have showed that the TST effect on Jc could be explained as a difference in the out-of-plane constraint and correlated with the out-of-plane T33-stress. Thus, in this work, the TST effect on Jc for the decommissioned Shoreham reactor vessel steel A533B was demonstrated from the standpoint of out-of-plane constraint. The results validated that T33 was effective for describing the Jc decreasing tendency. Because the Shoreham data included a lower bound Jc for increasing TST, a new finding was made that T33 successfully predicted the lower bound of Jc with increasing TST. This lower bound Jc prediction with T33 conquered the contradiction that the empirical Jc∝(TST)-1/2 predicts Jc = 0 for large TST.