High-temperature deformation behavior of Ti60 titanium alloy

Isothermal compressions of near-alpha Ti60 alloy were carried out on a Gleeble-3800 simulator in the temperature range of 960-1110 degrees C and strain rate range of 0.001-10.0 s(-1). The high-temperature deformation behavior was characterized based on an analysis of the stress-strain behavior, kinetics and processing map. The flow stress behavior revealed greater flow softening in the two-phase field compared with that of single-phase field. In two-phase field, flow softening was caused by break-up and globularization of lamellar a as well as deformation heating during deformation. While in the single-phase field, flow softening was caused by dynamic recovery and recrystallization. Using hyperbolic-sine relationships for the flow stress data, the apparent activation energy was determined to be 653 kJ/mol and 183 kJ/mol for two-phase field and single-phase field, respectively. The processing map exhibited two instability fields: 960-980 degrees C at 0.3-10 s(-1) and 990-1110 degrees C at 0.58-10 s(-1). These fields should be avoided due to the flow localization during the deformation of Ti60 alloy. (C) 2011 Elsevier B.V. All rights reserved.