Controlling the detrimental effect of hydrogen on the mechanical behaviour of advanced high strength steels is decisive for their application. Precipitates in steels can be useful in irreversibly trapping the hydrogen atoms, thereby preventing their diffusion to critical regions in the microstructure where they can be most detrimental. In this work, the capability of precipitates of transition metals in limiting the amount of diffusible hydrogen has been examined. A combined ab initio–experimental approach was used to study the hydrogen sorption in two DP800 steel grades with different concentrations of titanium and vanadium using cyclic voltammetry. Under the same charging conditions, diffusible hydrogen concentration was found to be higher in the vanadium grade as compared to the titanium grade. Scanning electron microscope characterisation revealed a more compact layer of oxide on the vanadium grade which contributed to more hydrogen absorption on the surface. Density Functional Theory calculations were performed to determine the trapping strength of precipitates of titanium and vanadium. C vacancy in titanium carbide was found to be the strongest hydrogen trap, but the C vacancy formation energy was much lower in vanadium carbide. At finite temperatures, however, both precipitates are experimentally known to be off-stoichiometric. Our DFT-based finding of the titanium grade being irreversible hydrogen trap is thus in agreement with the experimental results.
|Title of host publication||TMS 2021 150th Annual Meeting and Exhibition Supplemental Proceedings|
|Place of Publication||Cham, Switzerland|
|Publication status||Published - 2021|
|Event||150th Annual Meeting and Exhibition of The Minerals, Metals and Materials Society, TMS 2021 - Pittsburgh, United States|
Duration: 15 Mar 2021 → 18 Mar 2021
|Name||Minerals, Metals and Materials Series|
|Conference||150th Annual Meeting and Exhibition of The Minerals, Metals and Materials Society, TMS 2021|
|Period||15/03/21 → 18/03/21|
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- Advanced high strength steels
- Cyclic voltammetry
- Density functional theory
- Hydrogen trapping