Abstracts Book - IMRC 2018

• SE2-P016
EFFECT OF COBALT ADDITIONS ON MICROSTRUCTURES AND
MECHNICAL PROPERTIES OF ODS STEELS FOR HIGH
TEMPERATURE SERVICE APPLICATIONS
Sanghoon Noh 1 , Suk Hoon Kang 1
1 Korea Atomic Energy Research Institute, Nuclear Materials Division, Korea.
The core structural materials of next generation nuclear systems are expected
to operate under extreme environments, i.e., higher temperatures and neutron
irradiation dose rates than commercial light water reactors. To realize these
systems, it is necessary to develop advanced structural materials having high
creep and irradiation resistance. In these days, furthermore, advanced
structural materials have been noted for high temperature service applications
in fossil power, defense, aerospace industries and so on. Oxide dispersion
strengthening (ODS) is one of the most prospective ways to improve the
mechanical property at high temperatures in several alloys. This is mainly
attributed to uniformly distributed nano-oxide particle with a high density,
which is extremely stable at the high temperature and acts as effective obstacles
when the dislocations are moving. In this study, 9Cr-2W ODS steels with Cobalt
as a minor alloying element were fabricated by mechanical alloying and hot
isostatic pressing processes. And their microstructures and mechanical
properties at elevated temperatures were investigated. Cobalt is one of the
gamma phase former. To predict the phase in the fabrication process, the
electrical calculation was carried out with a commercial software. The ODS steels
showed the dual-phase microstructures co-existed with ferrite and martensite
grains. The fraction of martensite phase was increased with the Cobalt contents.
This led higher tensile strength than conventional ODS steels at elevated
temperatures.
Keywords: Oxide dispersion strengthening, Cobalt, Mechanical alloying
Presenting authors email: shnoh@kaeri.re.kr