Evaluation of fracture toughness from small specimens

The modified Gurson model is used to determine micromechanical toughness parameters of a weld material from the irradiation surveillance of a Reactor Pressure Vessel (RPV) mainly based on available results of instrumented Charpy tests. These parameters were used to numerically simulate static and dynamic fracture mechanics tests for the determination of J-resistance curves. The results were confirmed by means of experiments with irradiated specimens of the original material. The initiation values of the J-R curves converted into fracture toughness values K Ic allowed a conservative adjustment of the ASME reference toughness curve for the weld material.