The dynamic recrystallization condition and law of Ti6Al4V. alloy at all strain rates are investigated through thermal processing simulation test, split Hopkinson compression bar test and milling test. The theoretical calculation of the experimental results and the microstructure observation show that the dynamic recrystallization is possiblethe under the conditions of high strain rate and low strain rate. The model uses two expressions to express the material constitutive characteristics of different critical strain value intervals; the subprogram written in Fortran language is imported into AdvantEdge FEM software, and the finite element analysis of John-Cook constitutive and improved constitutive is carried out respectively. The comparative study of simulation proves that the improved constitutive equation is closer to the high temperature and high impact environment of high-speed cutting of titanium alloy, which has certain guiding significance for high-speed cutting of titanium alloy.

The Johnson–Cook (J–C) constitutive model is not suitable for Ti-6Al-4V alloy in the high-speed cutting finite element simulation, as it has no response dynamic recrystallization softening effect under heavy impact and high temperature. In this paper, an improved constitutive model considering the recrystallization effect was established, and the parameters were fitted with the data of flow stress–strain of the Split Hopkinson Pressure Bar (SHPB) test. The relevant theories of cutting finite element simulation were studied, such as nonlinear constitutive elastic–plastic deformation, strain state, and material yield. A subroutine that included the Recht shear failure instability criterion and the improved model was coded in Fortran and embedded in the finite element simulation software AdvantEdge FEM, along with the return mapping stress integration algorithm. The simulated stress of the improved model dropped dramatically from 460 MPa to 220 MPa when the temperature rises from 950 °C to 1000 °C, and its decline reached 46.7%, while the J–C model only decreased by 10%. Comparative studies indicate that the stress change of the improved constitutive simulation is closer to the SHPB test results than the J–C constitutive, and the new one is more suitable when it expresses the high temperature and heavy impact in the high-speed milling.