Mechanical behavior of oxide dispersion strengthened steels irradiated in JOYO

常陽原子炉で照射した酸化物分散強化鋼の機械的挙動

山下 真一郎   ; 吉武 庸光 ; 赤坂 尚昭; 鵜飼 重治  ; 木村 晃彦*

Yamashita, Shinichiro; Yoshitake, Tsunemitsu; Akasaka, Naoaki; Ukai, Shigeharu; Kimura, Akihiko*

酸化物分散強化型(ODS)鋼をさまざまな製造パラメータで製造し、照射挙動評価のため「常陽」で中性子照射試験した。応力-歪線図から、当該鋼は673Kで優れた照射後材料挙動を示した。すなわち、それは照射硬化による引張強度の増加及び全伸びの保存に見られる。また、引張特性の照射温度依存性からは、高温での引張特性の低下(照射下での相安定性と密接に関係)は、化学組成,メカニカルアロイング中の不活性ガス種,熱処理温度及び初期母相などの製造パラメータを最適化することで回避可能となることが示された。

Oxide dispersion strengthened (ODS) steels, which are candidate materials for water-cooled solid breeder blankets, were fabricated with several manufacturing parameters, and then irradiated in JOYO to evaluate their irradiation behavior. Engineering stress strain curve of ODS steels irradiated at 673 K exhibited superior material response, i.e., increased tensile strength due to irradiation hardening and no loss of total elongation. Also, their temperature dependence on tensile property indicated that degradation of the tensile property at elevated temperature, which is closely related to phase stability during irradiation, could be avoided due to optimal combination of manufacturing parameters, such as chemical composition, type of inert gas during mechanical alloying, heat-treatment temperature and initial phase of the matrix.