Model of local hydrogen permeability in stainless steel with two coexisting structures

Abstract

The dynamics of hydrogen in metals with mixed grain structure is not well understood at a microscopic scale. One of the biggest issues facing the hydrogen economy is “hydrogen embrittlement” of metal induced by hydrogen entering and diffusing into the material. Hydrogen diffusion in metallic materials is difficult to grasp owing to the non-uniform compositions and structures of metal. Here a time-resolved “operando hydrogen microscope” was used to interpret local diffusion behaviour of hydrogen in the microstructure of a stainless steel with austenite and martensite structures. The martensite/austenite ratios differed in each local region of the sample. The path of hydrogen permeation was inferred from the time evolution of hydrogen permeation in several regions. We proposed a model of hydrogen diffusion in a dual-structure material and verified the validity of the model by simulations that took into account the transfer of hydrogen at the interfaces.

Exploring the Effect of Microstructure and Surface Recombination on Hydrogen Effusion in Zn–Ni‐Coated Martensitic Steels by Advanced Computational Modeling

“…[32] The hydrogen diffusion coefficients of austenite and martensite are reported as 5.76  10 À7  expðÀ53.6 kJ=RTÞ m 2 s À1 and, 2.82  10 À7  expðÀ34.4 kJ=RTÞm 2 s À1 , respectively. [33] At room temperature, a difference of three orders of magnitude is observed between the diffusion coefficients of austenite and martensite. In the latter, the presence of retained austenite along the prior austenite GBs will significantly slow down the diffusion process.…”

“…- 34.4 \textrm{ } \text{kJ} / R T \left.\right) \left(\text{m}\right)^{2} \textrm{ } \left(\text{s}\right)^{- 1}$, respectively. [ 33 ] At room temperature, a difference of three orders of magnitude is observed between the diffusion coefficients of austenite and martensite. In the latter, the presence of retained austenite along the prior austenite GBs will significantly slow down the diffusion process.…”

Deposition, Morphological, and Mechanical Evaluation of W and Be-Al2O3 and Er2O3 Co-Sputtered Films in Comparison with Pure Oxides

“…The tritium inventory and control are not straightforward to be addressed due to several materials constraints imposed by future nuclear fusion reactor designs and configurations. For instance, the demonstration power station (DEMO) integrates inner walls made from low-activation steel, such as martensitic steel (i.e., EUROFER) that raises high hydrogen permeability 2 of 16 concerns [3][4][5][6][7]. Moreover, regardless of the configuration, hydrogen embrittlement is a more common and general problem limiting the operation time of the PFC integrated into the fusion reactor [8].…”

Visualization of Hydrogen Permeation Through Stainless Membrane Using Electron Stimulated Desorption

“…We also visualized the hydrogen released from the metal material through the hydrogen diffusion barrier coated on the substrate material [4]. In this paper, we will introduce the observation of hydrogen permeating through the metal sample and the model of hydrogen diffusion using the results [5]. The sample was cold rolled stainless steel which had regions with locally different balance between austenite and martensite but with the same overall chemical composition.…”

“…When the martensite percentage is low, hydrogen supplied from the bottom surface will diffuse through only the austenitic phase or only the martensite phase as it penetrates to the upper surface. On the other hand, when the martensite percentage is high, the austenite phase becomes fragmented by interspersed lath-like martensite phases, and hydrogen supplied from the bottom surface cannot diffuse only in the austenite phase to the upper surface [5].…”