关键词: TC4钛合金, 三维热拉弯成形, 回弹预测, 微观组织

Abstract: In order to solve the problems of 3D bending and forming of difficult-to-machine material profiles such as titanium alloy, a multi-point 3D hot stretch-bending process was proposed and the forming equipment was developed. The effects of the processing parameters such as pre-stretching amount, post-stretching amount and forming temperature on the 3D hot stretch-bending of L-shaped cross-section profiles for TC4 titanium alloy were explored through the forming tests. Among them, the forming temperature is the most important factor affecting the springback deformation. The best forming conditions are achieved when the pre-stretching amount is as 100%εs and the post-stretching amount is as 20%εs (εs is the yield strain parameter) at a certain temperature. Based on the results of forming tests and material mechanics property tests, a finite element simulation model was established to predict the forming processes and springback processes of multi-point 3D hot stretch-bending process, and the errors of springback prediction are less than 15%, which verifies the validity of the model. In addition, the microstructures of TC4 titanium alloy before and after forming processes were observed. The results show that compared with the initial undeformed sample, the phase transformation of TC4 titanium alloy after 3D hot stretch-bending is produced, the (101-0) grain surface texture intensity is significantly increased, the two-phase grain sizes are reduced, the plastic deformation ability of TC4 titanium alloy formed parts is improved, and the geometrically necessary dislocation density is increased.

Key words: TC4 titanium alloy, 3D hot stretch-bending, springback prediction, microstructure