A master curve analysis of F82H using statistical and constraint loss size adjustments of small specimen data

We assembled a fracture toughness database for the IEA heat of F82H based on a variety of specimen sizes with a nominal ASTM E1921 master curve (MC) reference temperature T0=−119±3 °C. However, the data are not well represented by a MC. T0 decreases systematically with a decreasing deformation limit Mlim starting at ≈200, which is much higher than the E1921 censoring limit of 30, indicating large constraint loss in small specimens. The small scale yielding T0 at high Mlim is ≈98±5 °C. While, the scatter was somewhat larger than predicted, after model-based adjustments for the effects of constraint loss, the data are in reasonably good agreement with a MC with T0=−98 °C. This supports to use of MC methods to characterize irradiation embrittlement, as long as both constraint loss and statistical size effects are properly accounted for. Finally, we note various issues, including sources of the possible excess scatter, which remain to be fully assessed.