Tensile Testing of Ti-6Al-4V Alloy Superplasticity

Abstract

This paper presents the research on the flow characteristics of the Ti-6V-4Al alloy in wide ranges of temperature (725 ‑ 950 °C) and strain rate (10-5 ‑ 10-2 s-1). The material processing maps were constructed based on the basis of dynamic materials model (DMM) developed by Prassad and modified by Narayana Murty. For the construction of such maps the data of the material flow stress at different temperatures and strain rates is necessary. To obtain such data the stepped tensile tests which allow obtaining the stress - strain rate dependence at a given temperature are ideal. The experiments conducted consist of the tensile test series at various temperatures with stepped change of the deformation rate. By the results of these tests the constitutive equations, which describe relationship between stress and strain rate for each temperature, were obtained. The data was analyzed in terms of the two different approaches proposed by Prassad and Narayana Murty to assess the impact of deformation conditions on the formability and flow stability of the material. Based on these approaches, the processing maps, which enable identifying the conditions of the Ti-6V-4Al alloy superplasticity, were constructed.