Evaluation of fracture toughness master curve shifts for JMTR irradiated F82H using small specimens

Small to ultra-small 1/3 size pre-cracked Charpy and 1.65 x 1.65 x 9 mm deformation and fracture minibeam (DFMB) specimens of the F82H IEA heat were irradiated to 0.02 and 0.12 dpa at 290 °C in the Japanese Materials Test Reactor. Nominal cleavage transition temperature shifts, based on the measured toughness, K jm (T), data (ΔT m ) as well as reference temperature shifts (ΔT 0 ) found after size-adjusting the K jm (T) data yielded ΔT m/0 ≈ 27 ± 10 and 44 ± 10 at the two doses, respectively. Using measured yield stress changes (Δσ y ), the C 0 = ΔT 0 /Δσ y = 0.58 ± 0.14 at 0.12 dpa, is in good agreement with data in the literature. The dynamic transition temperature shift, ΔT d , derived from DFMB tests, was ≈ 30 ± 20 °C at 0.1 dpa, also in good agreement with the estimated ΔT 0 shifts. The ΔT d and ΔT 0 are also in excellent agreement with a ΔT 0 = C 0 Δσ y (dpa, T i ) hardening-shift model, where the Δσ y (dpa, T i ) was found by fitting a large database of tensile properties.