Investigation of high temperature behavior and processing map of Ti-6Al-4V-0.11Ru titanium alloy

Abstract

The hot deformation behavior of Ti-6Al-4V-0.11Ru titanium alloy was investigated by isothermal compression under the conditions of deformation temperature ranging from 800 °C to 1100 °C and strain rate ranging from 0.01s−1 to 10s−1. The results revealed that the peak stress of Ti-6Al-4V-0.11Ru titanium alloy increased with decreasing the deformation temperature and increasing the strain rate, the softening mechanism was dynamic recovery below Tβ and changed to dynamic recrystallization above Tβ. The constitutive equation of Ti-6Al-4V-0.11Rualloy was calculated by a linear regression analysis in two phase regions in the form of Arrhenius-type relationships. It is found that the apparent activation energies were calculated to be 926.608 kJmol−1 in the α+β phase region and 128.947 kJmol−1 in the β phase region, respectively. A series of processing maps considering strain were drawn according to dynamic materials mode and Kumar's stability criterion, it can be found from processing maps that the strain had significantly effect on the peak region of power dissipation efficiencies in the processing map of Ti–6Al–4V-0.11Ru alloy and the flow instability region was very close to the optimum hot deformation condition at high strain. Furthermore, optimized hot working regions were investigated and validated through microstructure observation. The optimum thermo mechanical process condition for hot working of Ti-6Al-4V-0.11Ru titanium alloy was suggested to be in the temperature range of 900–950 °C with strain rate of 0.1-1s−1.