The Modeling of the Flow Behavior Below and Above the Two-Phase Region for Two Newly Developed Meta-Stable beta Titanium Alloys

Isothermal hot compression tests of two promising new titanium alloys (Ti-10 V-1Fe-3Al and Ti-10 V-2Cr-3Al) are performed using a TA DIL805D deformation dilatometer at temperatures in and above the two-phase α + β region (730–880 °C) at strain rates ranging from 10⁻³ to 10⁻¹ s⁻¹. Results show that the flow stress of the two alloys decreases with increasing deformation temperature and decreasing strain rate. Some of the flow curves manifest clear discontinuous yielding and flow softening, both of which are strongly affected by the deformation conditions. The flow stress behavior of these two alloys can be described very well by a hyperbolic–sine Arrhenius equation. When deforming in the α + β phase region, the deformation mechanism is governed by the bending or globularization of the α phase. When deforming in the pure β phase field, the flow behavior is mainly determined by dynamic recovery or recrystallization. The difference in alloy composition has a minor effect on their hot working behavior.