| 1. |
- Ornek, Cem, et al.
(författare)
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Hydrogen-Induced Micro-Strain Evolution in Super Duplex Stainless Steel-Correlative High-Energy X-Ray Diffraction, Electron Backscattered Diffraction, and Digital Image Correlation
- 2022
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Ingår i: FRONTIERS IN MATERIALS. - : Frontiers Media SA. - 2296-8016. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The local lattice strain evolution during electrochemical hydrogen charging and mechanical loading in 25Cr-7Ni super duplex stainless steel were measured in-situ using synchrotron high-energy x-ray diffraction. Post-mortem electron backscattered diffraction analysis showed that the austenite phase underwent plastic deformation in the near-surface due to hydrogen-enhanced localized plasticity, where the ferrite phase experienced hardening. In bulk regions, the ferrite was the softer phase, and the austenite remained stiff. Digital image correlation of micrographs recorded, in-situ, during mechanical tensile testing revealed intensified plastic strain localization in the austenite phase, which eventually led to crack initiation. The absorption of hydrogen caused strain localization to occur primarily in austenite grains.
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| 2. |
- Ornek, Cem, et al.
(författare)
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The causation of hydrogen embrittlement of duplex stainless steel : Phase instability of the austenite phase and ductile-to-brittle transition of the ferrite phase-Synergy between experiments and modelling
- 2023
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 217, s. 111140-
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Tidskriftsartikel (refereegranskat)abstract
- Various mechanisms have been proposed for hydrogen embrittlement of duplex stainless steel, but the causation of hydrogen-induced material degradation has remained unclear. This work shows that phase instability (decomposition) of the austenite phase and ductile-to-brittle transition of the ferrite phase precedes hydrogen embrittlement. In-situ diffraction measurements revealed that Ni-rich sites of the austenite phase decompose into metastable hydrides. Hydride formation is possible by increasing the hydrogen chemical potential during electrochemical charging and low defect formation energy of hydrogen interstitials. Our findings demonstrate that hydrogen embrittlement can only be understood if measured in situ and in real-time during the embrittlement process.
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| 3. |
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| 4. |
- Zhang, Fan, et al.
(författare)
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Corrosion-induced microstructure degradation of copper in sulfide-containing simulated anoxic groundwater studied by synchrotron high-energy X-ray diffraction and ab-initio density functional theory calculation
- 2021
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 184
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Tidskriftsartikel (refereegranskat)abstract
- Synchrotron high-energy XRD measurements and ab-initio DFT calculations were employed to investigate microstructural degradation of copper upon exposure to sulfide-containing anoxic groundwater simulating nuclear waste repository. After two-month exposure, the high-energy XRD measurements revealed heterogeneous lattice deformation in the microstructure and lattice expansion in near-surface regions. The DFT calculations show that sulfur promotes hydrogen adsorption on copper. Water causes surface reconstruction and promotes hydrogen insertion into the microstructure, occurring via interstitial sites next to vacancies leading to lattice dilation and metal bond weakening. Hydrogen infusion in the presence of sulfur caused lattice degradation, indicating a risk for H-induced cracking.
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