EVALUATION OF FRACTURE-TOUGHNESS BASED ON RESULTS OF INSTRUMENTED CHARPY TESTS

The modified Gurson model is used to determine micromechanical toughne ss parameters of a weld material from the irradiation surveillance of a reactor pressure vessel. These parameters were used to numerically s imulate static and dynamic fracture mechanics tests for the determinat ion of J-resistance curves. The results were confirmed by means of exp eriments with irradiated subsized specimens of the original material. The essential steps of the analysis-the consideration of rate-dependen t stress-strain curves and the determination of the material parameter s, as well as the numerical modelling of the boundary conditions at th e supports of the Charpy specimen-were validated by comparing analyses and experiments with a representative unirradiated submerged arc weld material. The initiation values of the J-resistance curves converted into pseudo-plane strain fracture toughness values K(Ic) allowed the c onservative adjustment of the ASME reference fracture toughness curve.