Effect of cyclic temperature variation on the mechanical properties and microstructures in F82H ODS steel irradiated by self-ions

Liu, C.*; Chen, S.*; Hashimoto, Naoyuki*; Onuki, Somei*; Shiba, Kiyoyuki; Jitsukawa, Shiro

Materials components of fusion reactors will undergo temperature variations during operation cycles due to non-steady state from the plasma. In this work, high energy self-ions irradiation was carried out to investigate the effect of temperature change on the mechanical properties and microstructural evolution in F82H ODS steel. The material used for this study was an oxide dispersion strengthened F82H ODS steel. The specimens were irradiated using 10.5 MeV Fe ions at the TIARA facility in JAEA to a total displacement damage level about 20 dpa. Irradiation temperature was executed with two constant temperature, 250C and 380C, vs. a periodic temperature (seven cycles). Nano-hardness in constant condition showed that the irradiation hardening was increased with the increase of temperature. Meanwhile, periodic temperature variation produced a moderate enhancement of irradiation hardening. TEM observation indicated that the dominant radiation induced defects were defect clusters.