Hot-deformation mechanisms in near-alpha titanium alloy 685

Using a dynamic materials model, processing and instability maps have been developed for a near- alpha titanium alloy 685 with low oxygen content in the temperature range of 775-1025 deg C and a strain-rate range of 0.001-10 s exp -1 with a view to optimizing its hot workability. This grade undergoes dynamic recrystallization with a peak efficiency of 55% at 975 deg C and 0.001 s exp -1 , which are the optimum parameters for hot working. Even though in conventional near- alpha titanium alloys the process of dynamic recrystallization is not reported, its occurrence in this particular grade is attributed to lower oxygen concentration, which may help in grain-boundary migrations required for the occurrence of the process.