Title: Evaluating the irradiation hardening of reactor pressure vessel steels by nanoindentation hardness test and micropillar compression test
Abstract: ABSTRACTABSTRACTUltra-small testing technologies (USTTs), such as nanoindentation hardness tests and micropillar compression tests, can be potentially used to measure the mechanical properties of irradiated materials. However, the hardness and yield strengths of USTTs are different from those of standardized methods on bulk samples. In addition, irradiation-induced defects can affect the size dependence on the mechanical properties. This study examined A533B reactor pressure vessel steels before and after 5 MeV electron irradiation using USTTs. The depth dependence of the nanoindentation hardness was analyzed using the Nix-Gao model to evaluate the bulk-equivalent nanoindentation hardness and confirm its good linear relationship with the Vickers hardness. The compression yield strength was evaluated with a truncated square pyramid shape micro-pillars where the edge length (d) of the top surface and the height (L) of the micropillars were made similar: (d, L) = (1,2), (2,4), (3,6), (4,8), and (8,16) in μm. The size dependence of the yield stress in the micropillars has a minimum at d = 2 µm, which remained unaffected by electron beam irradiation up to 22 mdpa. The average yield stress of the d = 4 and 8 µm specimens was similar to that of the bulk tensile specimens.ABSTRACTKEYWORDS: Mechanical propertyirradiationpost irradiation examinationreactor vessel steelnanoindentationmicropillarhardness AcknowledgmentsThis study was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI program (grant number 19H02643). The authors would like to thank the staff of the International Research Center for Nuclear Materials Science under the GIMRT Program of the Institute for Materials Research, Tohoku University (Proposal No. 202012-IRKMA-0411) for their kind support. The authors acknowledge Dr. Koji Fukuya and Dr. Katsuhiko Fujii for their kind support with the electron beam irradiation experiments. The author (Y. Zheng) would particularly like to thank Prof. Yasuyoshi Nagai and Prof. Akira Hasegawa for their valuable comments.Disclosure statementNo potential conflict of interest was reported by the author(s).Credit author statementYuyang Zheng: Conceptualization, Investigation, Writing – original draft, Diancheng Geng: Visualization, Hao Yu: Methodology, Sosuke Kondo: Methodology, Akihiko Kimura: Resources, Hideki Yuya: Resources, Ryuta Kasada: Supervision, Funding acquisition, Writing-reviewing, and editingAdditional informationFundingThis work was supported by the JSPS [19H02643]
Publication Year: 2022
Publication Date: 2022-05-09
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 1
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