Study on hydrogen embrittlement and dynamic strain ageing on low-alloy reactor pressure vessel steels

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

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en

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13

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Journal of Nuclear Materials, Volume 556

Abstract

Tensile tests in air with hydrogen pre-charged smooth specimens and slow strain rate tests with smooth and notched specimens in hydrogenated high-temperature water (HTW) at elevated temperatures (250−288 °C) on low-alloy reactor pressure vessel (RPV) steels revealed a softening in strength and a pronounced reduction in ductility, where the magnitude of hydrogen embrittlement (HE) increased with the dynamic strain ageing (DSA) susceptibility of the RPV steels. In hydrogen pre-charged specimens and in hydrogenated HTW, shear dominated transgranular fracture by microvoid coalescence with increasing amounts of macrovoids, quasi-cleavage regions and secondary cracking were observed. Thermal desorption spectroscopy showed an increase in the concentration of trapped hydrogen in high binding energy traps (vacancies & voids) induced by straining in DSA regime. The observed hydrogen effects on fracture behaviour is a consequence of plasticity localization resulting from the interaction between DSA and hydrogen. HESIV and HELP are the dominant HE mechanisms.

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Funding Information: The funding for the “SAFE-II” and “LEAD” projects from the Swiss Federal Nuclear Safety Inspectorate (ENSI) is gratefully acknowledged. The authors would like to express their gratitude for the experimental contributions and helpful suggestions from S. Ritter, H. Kottmann, B. Baumgartner, R. Schwenold and D. Stammbach from Paul Scherrer Institut. Publisher Copyright: © 2021 The Author(s)

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Rao, G S, Yagodzinskyy, Y, Que, Z, Spätig, P & Seifert, H P 2021, 'Study on hydrogen embrittlement and dynamic strain ageing on low-alloy reactor pressure vessel steels', Journal of Nuclear Materials, vol. 556, 153161. https://doi.org/10.1016/j.jnucmat.2021.153161