Flow behavior and 3D processing map for hot deformation of Ti-2.7Cu alloy

Highlights

• The hot deformation behavior of Ti-2.7Cu was analyzed.

• The activation energy and Arrhenius constitutive equation at strain 0.4 were calculated.

• 3D power efficiency diagram and 3D instability diagram were constructed.

• Processing map was constructed and optimum deformation parameters were acquired.

• The main deformation mechanism in the optimum zone was dynamic recrystallization.

Abstract

The isothermal constant strain rate compression test of Ti-2.7Cu alloy was carried out by Gleeble-3500 thermomechanical simulator. The hot deformation behavior at temperature of 740–890 °C and strain rate of 0.001–10 s⁻¹ was studied. The results show that the flow stress of the alloy is more sensitive to the deformation temperature and strain rate. The flow stress will decrease with the increase of deformation temperature, and increase with the increase of strain rate. The constitutive equation of Ti-2.7Cu is derived by using the Arrhenius hyperbolic sine function, and the activation energy at a strain of 0.4 is 412.32 kJ/mol. Based on the experimental data, the power dissipation efficiency and the instability parameter were investigated. Processing maps were established by superimposing the instability map and the power dissipation map. Through processing map prediction and microstructure observation, the unstable zones are mainly flow localization (740–750 °C /0.56  s⁻¹–10 s⁻¹) and mechanical instability (825 °C–890 °C /0.32 s⁻¹–10 s⁻¹), and the deformation mechanism of the stable zone is mainly dynamic recrystallization. It is found that the suitable deformation parameters of Ti-2.7Cu alloy are as follows: deformation temperature 780 °C–825 °C, strain rate 0.001 s⁻¹–0.056 s⁻¹.