TY - JOUR

T1 - Microstructural features and hydrogen diffusion in bcc FeCr alloys

T2 - A comparison between the Kelvin probe- and nanohardness based-methods

AU - Rao, Jing

AU - Sun, Binhan

AU - Ganapathi, Arulkumar

AU - Dong, Xizhen

AU - Hohenwarter, Anton

AU - Wu, Chun Hung

AU - Rohwerder, Michael

AU - Dehm, Gerhard

AU - Duarte, Maria Jazmin

N1 - Publisher Copyright: © 2024

PY - 2025/1/14

Y1 - 2025/1/14

N2 - Hydrogen embrittlement can cause a sudden failure in metallic materials, especially in industrially relevant alloys like steels. Understanding hydrogen's interactions with microstructural features is key to preventing hydrogen-induced damage and supporting a hydrogen-based economy. We use Kelvin probe-based potentiometric hydrogen electrode methods and thermal desorption spectroscopy to provide quantitative results on how controlled chromium contents, dislocation densities, and grain sizes affect hydrogen diffusion and uptake in FeCr alloys. The effective hydrogen diffusion coefficient for Fe–16Cr is ∼39 % higher than that of Fe–21Cr. While the hydrogen diffusion coefficient decreases with increasing Cr content, the hydrogen uptake increases with higher Cr content. For Fe–21Cr having 0.58 ± 0.01 wt.ppm hydrogen is measured, compared to 0.44 ± 0.02 wt.ppm for Fe–16Cr and 0.43 ± 0.01 wt.ppm for Fe–9Cr. In Fe–21Cr, a two-order of magnitude increase in dislocation density raises the hydrogen absorption from 0.58 ± 0.01 wt.ppm to 1.53 ± 0.05 wt.ppm and reduces the apparent hydrogen diffusion coefficient from (2.86 ± 0.03) × 10−6 cm2/s to (1.29 ± 0.01) × 10−7 cm2/s. Reducing the grain size from 1049 ± 51 μm to 0.3 ± 0.1 μm in the Fe–21Cr alloy lowers the apparent hydrogen diffusion coefficient from (2.86 ± 0.03) × 10−6 cm2/s to (1.92 ± 0.12) × 10−8 cm2/s, while increasing absorbed hydrogen from 0.58 ± 0.01 wt.ppm to 11.08 ± 0.12 wt.ppm. Finally, our newly developed nanohardness-based method is validated to determine the hydrogen diffusion coefficient using in situ nanoindentation testing. This approach allows simultaneous measurement of the dynamic mechanical response and hydrogen diffusivity in FeCr alloys during continuous hydrogen supply, as the hydrogen flow is unidirectional.

AB - Hydrogen embrittlement can cause a sudden failure in metallic materials, especially in industrially relevant alloys like steels. Understanding hydrogen's interactions with microstructural features is key to preventing hydrogen-induced damage and supporting a hydrogen-based economy. We use Kelvin probe-based potentiometric hydrogen electrode methods and thermal desorption spectroscopy to provide quantitative results on how controlled chromium contents, dislocation densities, and grain sizes affect hydrogen diffusion and uptake in FeCr alloys. The effective hydrogen diffusion coefficient for Fe–16Cr is ∼39 % higher than that of Fe–21Cr. While the hydrogen diffusion coefficient decreases with increasing Cr content, the hydrogen uptake increases with higher Cr content. For Fe–21Cr having 0.58 ± 0.01 wt.ppm hydrogen is measured, compared to 0.44 ± 0.02 wt.ppm for Fe–16Cr and 0.43 ± 0.01 wt.ppm for Fe–9Cr. In Fe–21Cr, a two-order of magnitude increase in dislocation density raises the hydrogen absorption from 0.58 ± 0.01 wt.ppm to 1.53 ± 0.05 wt.ppm and reduces the apparent hydrogen diffusion coefficient from (2.86 ± 0.03) × 10−6 cm2/s to (1.29 ± 0.01) × 10−7 cm2/s. Reducing the grain size from 1049 ± 51 μm to 0.3 ± 0.1 μm in the Fe–21Cr alloy lowers the apparent hydrogen diffusion coefficient from (2.86 ± 0.03) × 10−6 cm2/s to (1.92 ± 0.12) × 10−8 cm2/s, while increasing absorbed hydrogen from 0.58 ± 0.01 wt.ppm to 11.08 ± 0.12 wt.ppm. Finally, our newly developed nanohardness-based method is validated to determine the hydrogen diffusion coefficient using in situ nanoindentation testing. This approach allows simultaneous measurement of the dynamic mechanical response and hydrogen diffusivity in FeCr alloys during continuous hydrogen supply, as the hydrogen flow is unidirectional.

KW - bcc FeCr alloys

KW - Diffusible hydrogen

KW - Diffusion coefficient

KW - Hydrogen embrittlement

KW - Hydrogen traps

KW - In situ nanoindentation

UR - http://www.scopus.com/inward/record.url?scp=85214554764&partnerID=8YFLogxK

U2 - 10.1016/j.ijhydene.2024.12.433

DO - 10.1016/j.ijhydene.2024.12.433

M3 - Article

AN - SCOPUS:85214554764

VL - 102.2025

SP - 1103

EP - 1115

JO - International Journal of Hydrogen Energy

JF - International Journal of Hydrogen Energy

SN - 0360-3199

IS - 10 February

ER -