Proceedings of the Third International Conference on Metals & Hydrogen C02

# Hydrogen impact on the mechanical properties of three titanium alloys

## Quentin Bignon (1)1(2)2 , Frantz Martin (1)1 , Quentin Auzoux (1)1 , Yves Wouters (2)2

• (1) 1

Den-Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME), CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette, France

• (2) 2

Université Grenoble Alpes, SIMaP, F-38402 Saint Martin d’Hères, France

## Abstract

During long-term exposure to pressurised hot water (350 °C and 15 MPa), titanium alloys may absorb hydrogen. This study focuses on the determination of the impact of hydrogen on their mechanical properties. Specimens of three different titanium alloys – T40 ($\alpha$ phase), TA6V (4 % by volume of $\beta$ phase) and Ti10­2­3 (38 % by volume of b phase) – were hydrogen-charged up to 1240, 1630 and 1570 wt. ppm, respectively. Tensile tests at 20 °C and 300 °C under air environment at 10-4 s-1 were then conducted on both uncharged and charged specimens. Fracture surfaces and longitudinal cross-sections of the specimens were eventually observed by Scanning Electron Microscopy (SEM). Results obtained at 20 °C show that concentration of hydrogen in the range of 1200 - 1600 wt. ppm increases the ultimate tensile strength of the three materials and decreases their ductility. These effects are attributed to brittle hydrides owing to the low solubility of hydrogen in a phase at low temperature. Hydrogen also slightly decreased the yield stress of TA6V and Ti10­2-3. The same hydrogen concentration range did not reduce ductility of three materials at 300 °C. It could be due to the increase of hydrogen solubility with temperature or both increase of the hydrides plasticity and decrease of yield stress of the matrix with temperature.