The paper presents theoretical end experimental analysis of deformations and microstructural  evolutions  in the hot cogging process of Ti-6Al-4V alloy. A three–dimensional thermal – plastic coupled finite element model is employed to study the mechanical and thermal interaction between the forging anvils (conducted on three  tool types) and the workpiece. In this research, experimental flow curves of Ti-6Al-4V alloy were obtained using the isothermal hot compression test done at 800-1050 ^oC with 50 ^oC intervals, the strain rates ranging from 0.1 s^-1 to 5.0 s^-1 and the height reductions ranging from 0.105 to 0.693 at an interval of 0.105.

To explore the distributions of effective strain, effective  stress, mean stress  and  temperature of the specimens have been systematically studied. Attention has been paid to deformation, temperature, stress and strain inside the specimens and these parameters have been used to determine the evolution of the microstructure in deformed samples during hot cogging process. The Johnson–Mehl–Avrami–Kolmogorov theory was introduced to characterize the evolution of DRX volume fraction and grain size.

A comparison of theoretical with experimental results shows that the developed model may be used to accurately predict deformations and microstructural parameters.