Characterization of high-temperature deformation behavior and processing map of TB17 titanium alloy

Isothermal compression testing of a new high-strength TB17 titanium alloy was investigated on a Gleeble 3800 thermo-mechanical simulator over a temperature range of 775 degrees C-905 degrees C and a strain rate range of 0.001 s(-1) to 10 s(-1) with height reductions of 25%, 50% and 70%. Optical microscopy (OM), transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD) were employed to investigate the effect of deformation parameters on the microstructure and the deformation mechanism. The hot deformation behavior of TB17 titanium alloy is characterized by the analysis of the strain-stress curve, the strain rate sensitivity exponent and processing maps. The results show that the flow stress decreases with the increase of the deformation temperature and decrease of the strain rate. The strain rate sensitivity exponent m remains constant in alpha+beta phase field deformation and increases sharply in beta phase field. The TB17 titanium alloy has a narrow deformation field and the optimized deformation parameters is found at the temperature of 885 degrees C and the strain rate of 0.001 s(-1) at height reduction of 70%. The microstructure in the alpha vertical bar beta phase field deformation is characteristic of refined DRX alpha phase. While in the beta phase, the morphology is characteristic of refined beta grains. The increase of strain supported the occurrence of DRX at lower strain rates. The morphology is characterized by flow localization in instability domain. (C) 2016 Elsevier B.V. All rights reserved.