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The interaction between solute hydrogen (H) and mobile dislocations in Fe-24Cr-19Ni mass% (Type310S) austenitic steel charged with 8500 atomic ppm H was investigated by stress relaxation tests conducted over the temperature range 213–295 K. At ambient condition, H atoms form solute atmospheres that can migrate coordinately with moving dislocations. In contrast, the reduced H diffusivity at lower temperatures progressively impedes dislocation motion, leading to dynamic strain aging (DSA) during the relaxation process, manifested as a retardation of thermally activated deformation. As a direct consequence of this dislocation-pinning effect, a pronounced yield point emerged upon reloading after relaxation. The kinetics of solute atmosphere formation and DSA were further quantified by evaluating the exhaustion rate of mobile dislocation density as a function of relaxation time. The experimental trends were successfully described using a classical Cottrell atmosphere model based on size-misfit interaction, demonstrating that the fundamental role of H in governing dislocation mobility is essentially analogous to that of other interstitial solute elements.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: Austenitic steel, Hydrogen, Dislocations, Dynamic strain-aging

Date published: 2026-06-15

Publisher: Elsevier BV

Journal:

• Acta Materialia (ISSN: 13596454) vol. 316 122457

Funding:

• Japan Society for the Promotion of Science
• Iketani Science and Technology Foundation

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1016/j.actamat.2026.122457

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Updated at: 2026-06-25 13:47:18 +0900

Published on MDR: 2026-06-25 16:28:13 +0900