Plastic flow in Fe-Cr-Ni austenitic steel under the presence of solute H: A study via room temperature creep

作者：Yuhei Ogawa, Akinobu Shibata · 发表于：Acta Materialia · 年份：2024 · DOI：10.1016/j.actamat.2024.120659 · 被引用次数：12 · 研究领域：Hydrogen embrittlement and corrosion behaviors in metals、Microstructure and Mechanical Properties of Steels、Metal Alloys Wear and Properties

A connection between the effects of solute hydrogen (H) on macroscopic flow stress and microscopic dislocation mobility has been a subject for understanding the plastic flow behavior of H-charged austenitic steels and other face-centered cubic (FCC) alloys. In this study, we try to solve this problem by examining the room temperature creep of a Fe-24Cr-19Ni-based Type310S austenitic stainless steel uniformly charged with 9000 at ppm solute H in a pressurized gaseous H 2 environment. Stress-dip test to decompose the flow stress into effective (thermal) and internal (athermal) stresses, as well as a brief analysis of dislocation structure development in deformed uncharged and H-charged samples by electron channeling contrast imaging and hardness measurement, were supplementally employed. It is emphasized that solute H atoms consistently act as short-range obstacles hindering the movement of dislocations and thereby causes significant solid solution-hardening. Nevertheless, two opposite H-effects to accelerate and retard the creep rate were macroscopically identified depending on whether the stress level applied to H-charged specimens is above or below the flow stress under non-charged condition. These newly found, seemingly contradicting phenomena were interpreted based on the stress-dependent change of the rate-controlling mechanisms predominating thermally activated dislocation motion. Primary rate-controlling obstacles are H atoms themselves when creep acceleration manifests...