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A competitive relationship between solute atoms and forest dislocations in determining the kinetics of thermally activated plasticity was studied for a Type310S (Fe-24Cr-19Ni) austenitic steel containing ∼8500 at ppm hydrogen (H), where solute H promotes solid solution-hardening through an increase in the effective stress. The investigation was performed by constructing Haasen plot (i.e., strain rate sensitivity (SRS) vs. flow stress) based on stress relaxation tests, and by analyzing its evolution in relation to the decay of effective stress. In the regime of high effective stress, alloying solute elements—whose overcoming by dislocations is retarded by the presence of H—acted as primary rate-controlling obstacles to dislocations, giving rise to a relatively large and strain-independent SRS. In terms of Haasen plot, these manifested as an increase in the intercept and a decrease in the slope. Beyond the phenomenological findings of these H-induced characteristic changes, the present study elaborates their physical origin and transient nature. As the effective stress decreased and dislocation density increased, such predominance of solutes was progressively taken over by forest dislocations, leading the Haasen plot for H-charged specimens to approach that for non-charged specimen. These new insights further establish how H, alloying elements, and forest dislocations sequentially compete as rate-controlling obstacles depending on mechanical loading condition and internal state of the material.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: Austenitic steel, Hydrogen, Plastic deformation, Dislocations, Thermal activation

刊行年月日: 2026-07-20

出版者: Elsevier BV

掲載誌:

• Acta Materialia (ISSN: 13596454) vol. 317 122577

研究助成金:

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

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1016/j.actamat.2026.122577

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更新時刻: 2026-08-04 08:31:23 +0900

MDRでの公開時刻: 2026-08-04 10:45:59 +0900