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 × 1.65 × 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, KJm(T), data (ΔTm) as well as reference temperature shifts (ΔT0) found after size-adjusting the KJm(T) data yielded ΔTm/0 ≈ 27 ± 10 and 44 ± 10 at the two doses, respectively. Using measured yield stress changes (Δσy), the C0 = ΔT0/Δσy = 0.58 ± 0.14 at 0.12 dpa, is in good agreement with data in the literature. The dynamic transition temperature shift, ΔTd, derived from DFMB tests, was ≈30 ± 20 °C at 0.1 dpa, also in good agreement with the estimated ΔT0 shifts. The ΔTd and ΔT0 are also in excellent agreement with a ΔT0 = C0Δσy (dpa, Ti) hardening-shift model, where the Δσy (dpa, Ti) was found by fitting a large database of tensile properties.