Numerical analysis of cyclic residual stress induced by thermo-mechanical loads in high-speed milling of TC4 titanium alloy

Machining-induced residual stress significantly affects the fatigue life, geometric stability and service performance of machined components. This study presents a fully coupled thermo-mechanical two-dimensional (2D) Finite Element (FE) model to investigate residual stress distributions induced by High-Speed Milling (HSM) of TC4 titanium alloy. The model’s accuracy was validated by comparing the simulated outcomes with experimental data on chip segmentation, cutting forces and temperatures, with relative errors ranging from 6.85% to 12.40%. Beyond model verification, periodic fluctuations of plastic strain and residual stress in the machined surface and subsurface were simulated. Results showed tensile stress dominance at lower cutting speed (150 m/min), while compressive stress prevailed at higher speed (450 m/min), particularly for σ₁₁. Subsurface stress profiles exhibited hook-shaped distributions, with compressive stress peaking at depths of 7–10 μm and diminishing beyond 22 μm. A good correlation was observed between experimental and simulated results, with subsurface stress consistently compressive and increasing with cutting parameters. The effect of thermo-mechanical loads plays a critical role in shaping residual stress distributions; thermal loads primarily influence surface stress, whereas mechanical loads govern subsurface stress. This research provides a comprehensive understanding of residual stress behavior and its impact on fatigue life and service performance.