Ultra-high temperature creep rupture and transient burst strength of ODS steel claddings

Yano, Yasuhide  ; Sekio, Yoshihiro  ; Tanno, Takashi  ; Kato, Shoichi ; Inoue, Toshihiko ; Oka, Hiroshi   ; Otsuka, Satoshi   ; Furukawa, Tomohiro  ; Uwaba, Tomoyuki ; Kaito, Takeji ; Ukai, Shigeharu*

9Cr-ODS steel claddings consisting of tempered martensitic matrix, showed prominent creep rupture strength at 1000 C, which surpassed that of heat-resistant austenitic steels although creep rupture strength of tempered martensitic steels is generally lower than that of austenitic steels at high temperatures. The measured creep rupture strength of 9Cr-ODS steel claddings at 1000 C was higher than that from extrapolated creep rupture trend curves formulated using data at temperatures from 650 to 850 C. This superior strength seemed to be owing to transformation of the matrix from the -phase to the -phase. The transient burst strengths for 9Cr-ODS steel were much higher than those for 11Cr-ferritic/martensitic steel (PNC-FMS). Cumulative damage fraction analyses suggested that the life fraction rule can be used for the rupture life prediction of 9Cr-ODS steel and PNC-FMS claddings in the transient and accidental events with a certain accuracy.