Nano-meso Structures and Ring-tensile Properties of Neutron-irradiated ODS Steels

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山下 真一郎   ; 吉武 庸光 ; 赤坂 尚昭; 鵜飼 重治  ; 大貫 惣明

Yamashita, Shinichiro; Yoshitake, Tsunemitsu; Akasaka, Naoaki; Ukai, Shigeharu; Onuki, Somei

3種類のODS鋼被覆管(マルテンサイト系1鋼種とフェライト系2鋼種)を高速実験炉「常陽」で中性子照射し、照射下におけるナノ-メソ構造変化、リング引張強度変化をそれぞれ評価した。内部構造、とりわけ結晶粒の形態あるいは転位構造などのマクロ構造については、明確な照射後変化が認められなかったが、炭化物や酸化物分散粒子などのナノ構造については、全てのODS鋼で照射後変化が認められた。一方、リング引張特性に関しては、各種ODS鋼の照射温度依存性に有意な変化が現われた。これは、鋼種毎に微細構造変化が異なることを反映した結果と考えられる。

Three ODS steel claddings, one martensitic phase and two ferritic ones in initial structures, were neutron-irradiated in the experimental fast reactor, JOYO, and those nano-meso structural evolutions during irradiations and those ring-tensile behaviors at as close conditions as it should be in service were evaluated. As for the structural features, no significant structural changes in macro scale such as grain morphology and dislocation structure were recognizable, but those in nano scale such as carbide and oxide dispersoid emerged in all neutron-irradiated ODS claddings. With respect to the ring-tensile properties, on the other hand, a manifested variation of an irradiation temperature dependence among all the ODS claddings was revealed, reflecting the each microstructural evolution of ODS claddings during neutron irradiation.