Journal Article Effect of Cr/Al contents on the 475℃ age-hardening in oxide dispersion strengthened ferritic steels

Han, Wentuo  ,  Yabuuchi, Kiyohiro  ,  Kimura, Akihiko  ,  Ukai, Shigeharu  ,  Oono, Naoko  ,  Kaito, Takeji  ,  Torimaru, Tadahiko  ,  Hayashi, Shigenari

9pp.610 - 615 , 2016-12 , Elsevier BV
The age-hardening in oxide dispersion strengthened (ODS) ferritic steels with various additions of Cr (12, 15 and 18 wt.%) and Al (0, 5, 7 and 9 wt.%) were investigated. After 5000 h aging at 475ºC, the hardness increases in all these ODS steels, while the increased level depends on the Cr/Al contents. In 12Cr-ODS steels, the more the Al, the higher the increased hardness is. However, in 18Cr-ODS steels, higher Al addition suppresses the age-hardening. TEM observations of 18Cr-ODS steels reveal that 9Al suppresses the formation of Cr-enriched α' phase, while the 18Cr-5Al-ODS steel comprises a plenty of α′ phases. Adding Zr in ODS steels appears to increase the age-hardening. The susceptibility to age-hardening is remarkably lower in the ODS ferritic steels than in the non-ODS ferritic steel with the similar concentration of Cr.

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