Temperature Equilibrium Model and Bending Springback Behavior of TC4 Titanium Alloy under Current-Assisted Forming Conditions

TC4 (Ti-6Al-4V) titanium alloy has high specific strength and good corrosion resistance, but its poor room-temperature formability and severe springback limit high-precision forming. This study investigated the temperature evolution and bending springback behavior of TC4 titanium alloy during current-assisted forming. Electric heating tests, current-assisted three-point bending tests, finite element simulation, and microstructural observation were conducted. A temperature equilibrium model was established from energy conservation by considering Joule heat input, convection, radiation, and contact heat dissipation. Duty-cycle correction, die heat dissipation, and the Biot number were introduced to improve temperature prediction. The optimized model predicted equilibrium temperature with maximum errors of 5.6% under different duty cycles and 5.2% under different current densities. The model was then implemented in Abaqus to simulate the complete heating-bending-unloading springback process. The results show that increasing current density and decreasing loading rate significantly reduce springback. The minimum springback angle was 5.7° at a current density of 4.25 A/mm2 and a loading rate of 10 mm/min. Microstructural observations indicate that current application promotes the transformation of lamellar α phase into equiaxed α phase, increases the β-phase fraction, and enhances dynamic recrystallization at higher temperatures and lower strain rates. These effects reduce deformation resistance, improve plasticity, and provide a theoretical basis for parameter optimization and springback control in current-assisted precision forming of TC4 titanium alloy.