Evaluation of creep properties of reduced activation ferritic steels by small punch creep test

Reduced activation ferritic/martensitic steels (RAFs) are leading candidates for structural materials of fusion reactors. It is essential to understand an influence of irradiation on their mechanical properties such as impact toughness and creep properties to put them in practical use. However, since there are severe limitations on specimen capacity at material irradiation testing facilities, it is required to use miniaturized specimens. In this paper, creep properties of the RAFs, JLF-1 and F82H were evaluated by recently developed small punch (SP) creep test. The test results were correlated with those of standard uniaxial creep test in terms of the conversion of applied load to stress. Experimental results revealed that the relationship between minimum creep deflection rate and rupture life measured by the SP creep test followed the Monkman-Grant's low as well as those of uniaxial test. The rupture lives of uniaxial and SP tests were arranged against the applied stress and load using Larson-Miller parameter, respectively. Then, the ratio of load (F, N) to stress (σ, MPa) was calculated so that both curves were overlapped each other. As a result, the correlation was estimated to be F= 2.4σ and was consistent with that reported in the conventional CrMoV casting steel.