Effect of phase composition and hydrogen level on the deformation behavior of titanium-hydrogen alloys

Compression tests were carried out on a series of titanium-hydrogen alloys (containing up to 31 at. pct H) over the temperature range 500 degrees C to 1000 degrees C within the alpha, alpha + beta, and beta phase fields. The effect of hydrogen content was studied on the flow stress, rate of work hardening, and mechanical anisotropy. Hydrogen in solid solution produces significant softening of the alpha phase and (alpha + beta) phase mixture, while it induces hardening of the beta phase. The occurrence of strain softening was detected in the (alpha + beta) phase field as well, the extent of which depends on temperature, strain rate, and hydrogen concentration. The work required to deform the Ti-H alloys is sensitive to the hydrogen concentration and has the lowest value at interstitial levels that correspond to the (alpha + beta)/beta phase boundary at the temperature of interest.