Metal-hydride Characterization and Mechanical Properties of Ti-6A1-4V Alloy

Hydrogen absorption/dessociation properties and mechanical properties were examined in a Ti-6A1–4V alloy exposed to highly pressurized hydrogen gas of 0.1–5 MPa at elevated temperatures of 373 K to 773 K. Pressure-Concentration-Temperature (P-C-T) test results of the materials exhibit a large amount of hydrogen absorption up to 3 wt% H at 473 K with plateaus as observed in typical hydrogen absorption materials and the specimens tested are broken into pieces with the same level of hydrogen contents. Hydrogen dissociation from the material is not observed below 773 K. The results of bending tests and fractography show no degradation of mechanical properties of the materials with hydrogen contents of less than 0.1 wt% H. It is concluded from these test results that there is no mechanical degradation of Ti-6A1-4V vacuum vessel material for the tokamak device, JT-60SU due to metal-hydride reaction between Ti-6A1-4V and fuel hydrogen induced by hydrogen absorption mechanism into Ti-6A1-4V under the hydrogen pre...