Corrosion behavior of ODS ferritic steels made from elemental and pre-alloyed powders

プレミック粉末とプレアロイ粉末によって製造したODSフェライト鋼の腐食挙動

Lee, J. H.*; 笠田 竜太*; 木村 晃彦*; 奥田 隆成*; 井上 賢紀 ; 鵜飼 重治*; 大貫 惣明*; 藤澤 敏治*; 阿部 冨士雄*

Lee, J. H.*; Kasada, Ryuta*; Kimura, Akihiko*; Okuda, Takanari*; Inoue, Masaki; Ukai, Shigeharu*; Onuki, Somei*; Fujisawa, Toshiharu*; Abe, Fujio*

Oxide dispersion strengthened(ODS) ferritic steels are potentially considered as one of the candidate materials for fuel cladding in the supercritical water reactor, because of the high-temperature strength and the superior corrosion resistance. In this study, the corrosion behavior of ODS ferritic steels has been investigated to clarify the influence of different types of powder on corrosion resistance of the materials in SCW. ODS ferritic steels prepared by elemental and pre-alloyed powders were exposed to the open-loop system of SCW from 400 to 600C with 8ppm of dissolved oxygen under a pressure of 256MPa for time periods up to 2000hr. The corrosion rate was evaluated from the weight gain per unit surface area of a specimen. The surface and cross-sectional morphologies of corrosion products and the corresponding chemical compositions were characterized by means of FE-SEM, XRD, and FE-EPMA. After the SCW exposure it is found that the corrosion resistance of ODS steels fabricated by elemental powders is better than that of the materials fabricated by pre-alloyed powders. Furthermore, the 4Al-ODS steels added with Zr and Hf showed an excellent corrosion resistance at higher temperature than the ODS steel without addition of Al.