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The Ti-6Al-4V (TC4) is subjected to an isothermal compression test by the Gleeble-3800 thermal simulation testing machine, and the stress–strain curve is obtained, and the experimental data are corrected by friction. Through dynamic recrystallization (DRX) dynamic analysis and simulation, the microstructure evolution and hot compression behavior of TC4 titanium alloy under different deformation conditions are studied. The DRX behavior confirmed by microstructure observation is promoted at higher temperature and lower strain rate. In the compression process, when $$\dot{\varvec{\varepsilon} }=1{s}^{-1}$$ , its softening effect increases significantly with the increase in temperature. When $$\dot{\varvec{\varepsilon} }=0.001{s}^{-1}$$ and $$\dot{\varvec {\varepsilon} }=0.01{s}^{-1}$$ , the softening effect is not obvious. At 1223K, the flow softening extent increases with the increase in strain rate where DRX plays a dominate role in the softening behavior. TC4 titanium alloy has obvious discontinuous yield behavior under high-temperature compression deformation conditions, and the yield value is not significantly correlated with the increase in deformation temperature. The DRX kinetics model was established to calculate the volume fraction and grain size of DRX under the investigated deformation parameters. In addition, the relationship between microstructure and deformation behavior and mechanical properties is also discussed. The excellent correlation shows that the organization and mechanical properties can be controlled by selecting suitable deformation parameters. Finally, the finite element model is combined with the kinetic equation to predict the microstructure of TC4 titanium alloy after hot compression. The result shows that the predicted value is highly consistent with the experimental value. The error of the recrystallization volume fraction does not exceed 10%. This shows that the model has excellent applicability in current research and has huge practical application potential in predicting the mechanical properties of TC4 titanium alloy after hot working.

Ti-6Al-4V (TC4) alloy is a (α + β) two-phase titanium alloy and has good process plasticity, superplasticity, and corrosion resistance. It is widely used in the aerospace industry. During the hot working process, the microstructure and deformation behavior affect its mechanical properties. However, most of the current research focuses on the use of metallographic methods and physical modeling methods to characterize and estimate the evolution of microstructures and lacks accuracy. Therefore, in this study, the thermal deformation behavior of TC4 titanium alloy is predicted and the dynamic recrystallization process is visualized through thermal simulation test, metallographic test, particle swarm optimization–backpropagation (PSO–BP) algorithm, and cellular automata (CA) method. The conclusions are as follows: the grain growth of TC4 titanium alloy is relatively uneven during hot compression. The increase in temperature and the decrease in strain rate are favorable to dynamic recrystallization. After hot compression, the grain texture appeared in the microstructure of TC4 titanium alloy, and the type and strength of texture changed with the change in temperature. Based on the PSO–BP algorithm, the rheological behavior of TC4 titanium alloy during hot compression is predicted. Compared with the experimental value, the correlation of the PSO–BP model is 0.9972, and the error is within 10%. Finally, using the PSO–BP algorithm as the input, combined with the CA method and the related theory of dynamic recrystallization, the dynamic recrystallization behavior of TC4 titanium alloy during hot compression is simulated. The electron backscatter diffraction test is used for comparison, and the simulated microstructure is similar to the experimental structure after removing the influence of some defects. The average grain size error is within 10%. It shows that this model can well predict the dynamic recrystallization behavior of TC4 titanium alloy during hot compression.