Multi-objective optimization design and verification of extrusion die structure for TC4 titanium alloy Y-section profile

This study focuses on the multi-objective optimization design of high-temperature extrusion die structures for TC4 titanium alloy Y-shaped profiles used in the aerospace field. A high-precision Hansel-Spittel constitutive model of TC4 titanium alloy was established to provide a basis for numerical simulation analysis. The accuracy of the model was verified by the correlation coefficient ( R = 0.9910) and the average absolute relative error (AARE = 8.90%), demonstrating its capability to accurately characterize the material’s flow behavior. Combining numerical simulation with a multi-objective optimization algorithm, a second-order response surface model was developed based on the Box-Behnken experimental design to relate die structural parameters to optimization objectives. The optimal die structure was obtained using the NSGA-II genetic algorithm. Results indicated that compared to the initial structure, the optimized die achieved: A 96.6% reduction in the relative exit velocity difference of the profile; A 7.44% decrease in the maximum surface temperature difference; A 4% reduction in extrusion force. This research provides a critical reference for extrusion die design and process optimization in related industrial applications. The optimized die structure was manufactured and subjected to actual hot extrusion experiments, demonstrating observable quality enhancement of the profile.