During the cutting process, substantial shear deformation occurs in the workpiece material, particularly during high-speed machining. A noteworthy characteristic of mechanical machining lies in the workpiece material experiencing exceptionally high temperatures and strain rates. Describing material behavior during such significant plastic deformation poses challenges when employing classical plasticity theories. In practice, there exists a highly nonlinear relationship between flow stress and strain, strain rate, and temperature during the machining process. Consequently, to circumvent costly and technically demanding experiments, finite element analysis (FEA) emerges as one of the most effective methods for investigating cutting mechanisms [
5]. As a result, finite element simulations are commonly utilized to optimize process parameters and predict cutting performance.
Various empirical and statistical models have been proposed by previous researchers, among which the Johnson–Cook (J–C) model, developed by Johnson and Cook [
6], has found widespread application in the manufacturing field. Additionally, the Power-law model [
7], Zerilli–Armstrong (Z–A) model [
8,
9,
10], and Mechanical Threshold Stress (MTS) model [
9] have also been developed. Out of these models, the J–C model occupies a prominent position as one of the most extensively utilized mechanical machining plastic constitutive models. Its popularity is attributed to its favorable modeling results, simplicity, and comprehensive consideration of the effects of strain, strain rate, and temperature [
11,
12,
13,
14,
15,
16]. The J–C model has been successfully used by many researchers to predict machining force, temperature, and residual stress and to predict materials’ failure behaviors under various loading and temperature conditions [
17].
Lee and Lin [
18] explored the high-temperature deformation behavior of Ti-6Al-4V alloy using the Hopkinson bar test. To describe the flow characteristics of the material under different strains, strain rates, and temperatures, they established the Johnson–Cook constitutive model. Calamaz et al. conducted cutting tests on Ti-6Al-4V alloy and found that with increasing strain rate, the material transitioned from strain hardening to softening. They analyzed this phenomenon in relation to the dynamic recovery recrystallization mechanism of the material, and proposed the hyperbolic tangent (TANH) modified constitutive model for the Johnson–Cook model [
19]. Jinhua et al. [
20] proposed a reverse method for determining the Johnson–Cook parameters. They combined the experimental data of cutting forces and chip thickness and used the particle swarm optimization (PSO) algorithm to optimize the model. Through orthogonal cutting tests, they successfully identified the Johnson–Cook model for the nickel-based super-alloy Inconel 718. Zhou et al. [
21] established a correlation between the parameters of the Johnson–Cook constitutive model and the cutting force, and subsequently employed the firefly optimization algorithm to enhance the constitutive model. They further utilized the unequal division parallel-sided shear zone model for orthogonal cutting to predict the cutting force. Shen et al. [
22] introduced a parametric identification approach to enhance the accuracy of finite element simulation in the cutting process. They achieved this by employing a Johnson–Cook constitutive model of the material. Their research involved the establishment of various Johnson–Cook constitutive models for TC17 titanium alloy, accomplished through the use of the split Hopkinson pressure bar (SHPB) and the parameter identification method. Ren et al. [
23] proposed a modified Johnson–Cook constitutive model (MJC) for Ti-6Al-4V titanium alloy, which includes a hyperbolic tangent failure function. They optimized the model by using experimental cutting forces and the added Johnson–Cook coefficients as objectives and design variables, respectively. The verification results showed that the established constitutive model accurately predicted cutting forces in accordance with practical standards. Gao et al. [
24] conducted hot tensile tests on Ti-6Al-4V alloy sheets at varying temperatures (650 °C, 700 °C, and 750 °C) and different strain rates (0.1 s
−1, 0.01 s
−1, 0.001 s
−1). In their research, they introduced a novel Johnson–Cook model, wherein the softening coefficient “m” was treated as a function of strain rate, and a temperature correction function was incorporated into the model. Sedaghat et al. [
25] conducted a systematic analysis of four typical constitutive models: Johnson–Cook, Khan–Huang–Liang (KHL), Zerilli–Armstrong (Z–A), and Gao–Zhang (G–Z). They developed an improved constitutive model that considered the dislocation drag mechanism. The enhanced model accurately predicted the sudden increase in flow stress for all face-centered cubic (FCC), hexagonal close-packed (HCP), and body-centered cubic (BCC) materials. Özel and Karpat [
26] combined the Johnson–Cook constitutive model with the cooperative particle swarm optimization (CPSO) method to study the influence of high strain rates, thermal softening, and strain rate–temperature coupling on material flow stress. They determined the constitutive model parameters using evolutionary algorithms. Four methods were employed to ascertain the measurement of flow stress data during the machining process. The initial approach involved high-speed compression testing. However, this method encountered limitations, including slow heating rates and insufficient deformation rates to prevent sample soft annealing or age hardening [
27]. Furthermore, the maximum strain rate attainable was confined to approximately 10
2 s
−1. In response to these challenges, a separate Hopkinson pressure bar (SHPB) test was conducted to measure flow stress under higher strain rates and elevated temperature conditions [
28,
29]. Although this test successfully circumvented soft annealing and age hardening phenomena, the strain rates achieved remained below 10
4 s
−1, significantly lower than the strain rates experienced in the mechanical machining process, which typically range from approximately 10
4 s
−1 to 10
6 s
−1 [
30]. Meanwhile, Xu Runrun and Jian-bo Li [
31,
32] separately described the thermodynamic properties of different compositions of TiAl alloys under low strain rates by constructing an Arrhenius constitutive model [
31,
32]. However, the machining of γ-TiAl alloy involves deformation under high temperatures and strain rates.
To investigate the thermal deformation behavior of γ-TiAl alloy during machining, this study performed quasi-static compression tests and Hopkinson pressure bar tests under high temperatures and strain rates. The Johnson–Cook constitutive model was established, and the stress–strain results were analyzed based on correlation and absolute error criteria. Furthermore, considering the coupling effect of strain rate, temperature, and strain, the constitutive model was further modified to better describe the material’s deformation process.