Microstructure and Mechanical Properties of Ultrafine-Grained Austenitic Oxide Dispersion Strengthened Steel
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FERRITIC/matensitic oxide dispersion strengthened (F/M ODS) steel is considered as one of the most promising candidate material for the fuel claddings of next generation fast reactors,[1,2] and have been under intensive development for more than a decade.[3–12] Austenitic steels, however, usually show better corrosion and oxidation resistance than F/M steels, and have been widely used as core structural materials of the pressurized water reactors or fuel cladding materials for fast reactors. Due to the high swelling rate of the austenitic stainless steels at high fluence levels, face-centered cubic (FCC)-structured materials limit their applications at low or intermediate fluence levels.[1,2] It is expected that austenitic steels could be a better candidate material for
XIAODONG MAO, Associate Professor, formerly with the Nuclear Materials Development Division, Korea Atomic Energy Research Institute, Daedeokdaero 989-111, Yuseong, Daejeon, 34057, Republic of Korea, is now with the Institute of Nuclear Energy Safety Technology, CAS, Hefei, China. Contact e-mail: jjang@kaeri. re.kr SUK HOON KANG, Senior Researcher, and TAE KYU KIM and JINSUNG JANG, Principal Researchers, are with the Nuclear Materials Development Division, Korea Atomic Energy Research Institute. SEUL CHAM KIM, Postdoctoral Researcher, formerly with the Department of Materials Science and Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea, is now with the University of Colorado at Boulder, Boulder. KYU HWAN OH, Professor, is with the Department of Materials Science and Engineering, Seoul National University. Manuscript submitted January 31, 2016. METALLURGICAL AND MATERIALS TRANSACTIONS A
fuel claddings or core structural components if the swelling resistance can be improved by precipitation or grain refinement. For instance, precipitation of fine TiC or M2P precipitates in Fe-Cr-Ni austenitic steel with controlled Ti and P additions has been proved to extend the low-swelling transient regime up to 100 dpa.[13,14] Austenitic stainless steel with ultrafine grains also exhibits higher irradiation resistance than the conventional coarse-grained one.[15–17] Both methods are based on the high annihilation of point defects at the precipitates or grain boundaries. However, dissolution of TiC under irradiation makes it not fully adequate for high irradiation dose applications.[18] UFG metals and alloys are subjected to rapid grain growth at elevated temperatures due to the high volume fraction of the grain boundaries.[19] AODS steel with UFG microstructure could combine the advantages of those two cases, which makes it possible to significantly enhance the swelling resistance of austenitic steels. Oxide particles in ODS steels exhibit extremely high resistance to irradiation even at high doses.[20–22] UFG structure could be stabilized by the highly stable nano-sized oxide particles on the grain boundaries even at extreme conditions.[23,24] There have been several reports on the fabrication, microstructure analys
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