Tensile response of ductile α-titanium at moderately high strain rates

Abstract

The tensile behavior of Grade 2 α-titanium is characterized for static loading and at moderately high strain rates (200-1000 s-1). An experimental method is proposed to introduce sufficiently long tensile pulses to induce fracture in ductile specimens by incorporating a sacrificial fracture piece of adequately large diameter into a pendulum-driven tensile Kolsky bar. It is established that flow stress increases with strain rate. Necking in α-titanium occurs much earlier at high strain rates compared to static loading and results in significantly smaller necking and fracture strains. An equation describing the influence of strain rate and temperature softening on necking (tensile instability) is derived. The true stress-strain response between necking and fracture is estimated by measuring the final reduction in cross-sectional area. Fracture in specimens was observed using an optical microscope, which revealed typical ductile fracture characteristics. © 2001 Elsevier Science Ltd. All rights reserved.