Microstructural mechanisms during hot working of commercial grade Ti–6Al–4V with lamellar starting structure

Hot Deformation Behavior of Ti–6Al–4V Alloy in β Phase Field and Low Strain Rate

“…The apparent activation energy for hot deformation of Ti-6Al-4V in b phase field is estimated to be about 168.5 kJ/mol, which is comparable with the activation energy calculated by Prasad et al [28]. The calculated apparent activation energy in this study is comparable to that calculated for the self-diffusion in b-Ti (153 kJ/mol) [8]. This confirms that the DRX mechanism in b phase field is a diffusion-controlled phenomenon.…”

“…Actually, the prior b grains are transformed into martensite structure (a 0 ), whereas their boundaries are retained under this condition [26]. However, this phase transformation makes the detection of dynamic recrystallized grains very difficult [8] and can result in lower quality light micrograph images of the as-quenched microstructure.…”

“…Recent studies on equiaxed [7] and lamellar [8] b phase field Ti-6Al-4V microstructures reveal that dynamic recrystallization (DRX) occurs during hot deformation at strain rate range of 10 -3 -10 -1 s -1 . DRX is now recognized as one of the softening mechanisms in hot deformation of crystalline materials [9].…”

An experimental study of deformation mechanism and microstructure evolution during hot deformation of Ti–6Al–2Zr–1Mo–1V alloy

“…Commonly, the temperature and strain rate dependence of flow stress in hot deformation can be described by Arrhenius kinetic rate equation given by [25,26]:…”

“…Actually, different researchers related such high deformation activation energy to different reasons in addition to the dynamically recrystallization, deformation twining and phase transformation mentioned above, e.g. the effect of stress on activation energy [25], and the globularization of lamellar microstructure [35].…”