Assessment of irradiation embrittlement of the Eurofer97 steel after 590 MeV proton irradiation

The irradiation hardening of the Eurofer97 steel following 590 MeV proton irradiations was determined at three different irradiation temperatures, 50 °C, 250 °C and 350 °C, and various doses up to about 1.3 displacement per atom. The dose and temperature dependence of the irradiation hardening was characterized by a linear relationship between the irradiation hardening and the square root of the dose as: delta_yield_stress=k(T)dpa^1/2. Mini pre-cracked bend bar (1x1x16 mm3) were also tested in the lower ductile to brittle transition region before and after irradiation at 300 °C and 0.5 dpa. The effective fracture toughness-temperature curves, Ke(T), were indexed on an absolute temperature scale at To for Ke=100 MPa m1/2 for both the unirradiated and irradiated condition. The irradiation-induced temperature shift delta_To of the Ke(T) curves yielded a coefficient Co, defined as Co=delta_To /delta_yield_stress, of about 0.53. For these low doses, helium effects could not be identified on the fracture properties.