IAEA coordinated research project on master curve approach to monitor fracture toughness of RPV steels; Applicability for highly embrittled materials

Planman, T.*; Onizawa, Kunio ; Server, W.*; Rosinski, S.*

In the Master Curve (MC) fracture model, a universal temperature dependence is assumed for reactor pressure vessel (RPV) steels. The assumed curve shape has been observed to be generally valid for highly irradiated materials. Lower than predicted fracture toughness behavior has been occasionally observed, however, in the upper transition range. One objective of the present IAEA CRP is to clarify the MC shape issue by collecting and analyzing relevant fracture toughness data on irradiated or thermally aged RPV steels. The data reviewed in this CRP show, in general, a very consistent fracture behavior with the basic MC model that further confirms the applicability of the assumed curve shape. In cases where the basic assumptions of the MC model were not satisfied due to high proportions of intergranular fracture, correspondence with the measured and predicted behavior could be markedly improved by applying available models developed to address inhomogeneous materials.