Effect of α phase fraction on the dynamic mechanical behavior of a dual-phase metastable β titanium alloy Ti–10V–2Fe–3Al

Abstract

Abstract Dynamic mechanical behavior of a metastable β titanium alloy Ti-10V-2Fe-3Al (Ti-1023) with α+β dual-phase structure is investigated by a split Hopkinson tension bar (SHTB) system at two high strain rates of 2000 s-1 and 4000 s-1. α phase fraction in Ti-1023 alloy is tuned via different heat treatments. Dynamic tensile stress-strain curves, deformation mechanisms and fracture are discussed in detail. As α phase fraction decreases from 60.5% to 4.5%, there is a transition from one-stage to three-stage work hardening, as well as a transition from single-to double-yielding phenomenon, which is caused by stress-induced martensitic transformation (SIMT). Positive strain rate effects are found on yield strength, ultimate tensile strength and triggering stress, while negative strain rate effect is found on uniform elongation of dual-phase Ti-1023 alloy. The connections between deformation mechanisms (including SIMT, hierarchical α martensite structures, kinking and dislocation slip) and dynamic mechanical properties are discussed in detail. No adiabatic shear bands are found in the solution-treated alloys under SHTB loading.