| People | Locations | Statistics |
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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Drexler, Andreas
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (12/12 displayed)
- 2024Hydrogen Solubility in Steels – What is the Role of Microstructure?
- 2023Critical verification of the effective diffusion conceptcitations
- 2023Effect of Tensile Loading and Temperature on the Hydrogen Solubility of Steels at High Gas Pressurecitations
- 2022Enhanced gaseous hydrogen solubility in ferritic and martensitic steels at low temperaturescitations
- 2022Influence of Plastic Deformation on the Hydrogen Embrittlement Susceptibility of Dual Phase Steelscitations
- 2022Viscoplastic Self-Consistent (VPSC) Modeling for Predicting the Deformation Behavior of Commercial EN AW-7075-T651 Aluminum Alloycitations
- 2022Resistance of Quench and Partitioned Steels Against Hydrogen Embrittlementcitations
- 2022The role of hydrogen diffusion, trapping and desorption in dual phase steelscitations
- 2021Critical verification of the Kissinger theory to evaluate thermal desorption spectracitations
- 2021Modeling of Hydrogen Diffusion in Slow Strain Rate (SSR) Testing of Notched Samplescitations
- 2020Cycled hydrogen permeation through Armco iron – A joint experimental and modeling approachcitations
- 2020Hydrogen embrittlement (HE) of advanced high-strength steels (AHSS)
Places of action
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article
Critical verification of the effective diffusion concept
Abstract
<p>Knowing the hydrogen distribution <i>c</i>(<i>x</i>,<i>t</i>) and local hydrogen concentration gradients grad(<i>c</i>) in ferritic steel components is crucial with respect to hydrogen embrittlement. Basically, hydrogen is absorbed from corrosive or gaseous environments via the surface and diffuses through interstitial lattice sites into bulk. Although, the lattice diffusion coefficient <i>D</i><sub>L</sub>∼0.01mm<sup>2</sup>/s is in the order of magnitude of those for well-annealed pure iron, trapping sites in the microstructure retard the long-range chemical diffusion <i>j</i><sub>L</sub>=−<i>D</i><sub>chem</sub>(<i>c</i>)grad(<i>c</i>), causing local hydrogen accumulation in near surface regions in limited time. Considering pure ferritic crystals without trapping sites in the microstructure, the limited characteristic diffusion depth <i>x</i><sub>c</sub>∼√<i>D</i><sub>eff</sub><i>t</i> is proportional to the square root of the effective diffusion coefficient <i>D</i><sub>eff</sub> and of time <i>t</i>. Effective diffusion coefficients are measured independently for hydrogen using the electrochemical permeation technique. For pure crystals, the effective diffusion coefficient is constant at given temperature and allows accurate calculations of the diffusion depths. However, with trapping sites in the microstructure the effective diffusion coefficient is not a material property anymore and becomes dependent on the hydrogen charging conditions. In the present work, the theory of hydrogen bulk diffusion is used to verify the concept of effective diffusion. For that purpose, the generalized bulk diffusion equation was solved numerically by using the finite difference method (FDM). The implementation was checked using analytical solutions and a comprehensive convergence study was done to avoid mesh and time dependency of the results. It is shown that effective diffusion coefficients can vary by magnitudes depending on the sub-surface lattice concentration. This limits the application of the effective diffusion concept and also the calculation of the characteristic diffusion depth.</p>