Effect of hydrogen on the superplasticity of Ti40 alloy with large grains

Thermohydrogen processing (THP) is an attractive approach which uses hydrogen as a temporary element in titanium alloys to modify the microstructure/mechanical properties and workability. In this article, the influence of hydrogen on the superplasticity of single β phase Ti40 (Ti-25V-15Cr-0.2Si) alloy with hydrogenation had been investigated in the temperature range of 840-920°C and strain rate of 5×10^-4-1×10^-2s^-1. The maximum elongation of 478% was obtained at 920°C, 5×10^-4s^-1 with 0.3wt.% H. A significant refinement of average grain size in Ti40-xH alloys during superplastic deformation was found and the grain sizes became much finer with the increase of hydrogen content. The superplastic deformation mechanism of Ti40-xH alloy with large grains could be explained by dynamic recovery and recrystallization.