A phenomenological model based on the combination of the Garofalo and Hensel–Spittel equations is used to obtain a quite accurate description of the flow curves of Ti–6Al–4V alloy for processing temperatures between 1010 and 1150°C and strain rates of 100, 50, 10, 1, 0.1, 0.001 s^–1. The hot deformation is achieved by dynamic recovery in the β phase by subgrain formation. The activation energy of the dynamic recovery Q_HW is determined as 202 kJ/mol and the stress exponent n is 3.92. The analysis of the experimental data by constitutive model shows an excellent result of describing the flow curves.

Hot deformation behavior of an Inconel 718 superalloy was investigated by hot torsion tests over wide ranges of strain rate and temperature. In this study, the effects of hot deformation parameters (deformation temperature and strain rate) on flow stress are analyzed. The flow stress of the solution treated superalloy was significantly affected by deformation temperature and strain rate, the samples were then deformed in the temperature range 1050–1100°C, under strain rates of 0.01, 0.1, and 1 s^–1. The flow stress decreased with strain rate or the increase of deformation temperature. Based on the experimental results, a constitutive model was developed to describe the hot deformation behavior. The microstructural analysis of the testing samples were performed, in order to correlate the microstructural state with the mechanical properties of the Inconel 718.