Abstract
Two representative grades of hot-rolled titanium alloys, pure Ti grade 2 (T40), α single-phase and dual phase (α+β) Ti64 grade 23 ELI (TA6V) alloys, are subjected to different loadings under hydrogen gas pressure from 3 to 400 bars, coupled with temperatures from 20 to 500°C. After hydrogen loading, the overall amount of hydrogen absorbed by the material is measured by the carrier gas method, while the resulting microstructures are analysed by Scanning Electron Microscopy (SEM)- Electron Backscatter Diffraction (EBSD) and X-ray diffraction (XRD).
The obtained results show the precipitation of mainly γ-TiH and δ-TiHx hydrides. Their surface and volume distribution appears strongly dependent on the hydrogen charging conditions, which are optimised to avoid damage during hydrogenation in severe conditions. A comparative study with respect to reference conditions is carried out on hydrogenated specimens subjected to simple shear and to tensile tests on small devices. The results show a significant effect on mechanical properties after hydrogen charging.