FEM simulation of vacuum hot bulge forming process of BT20 titanium alloy cylindrical workpiece

Bulge forming is an innovative manufacturing process used to produce many industrial components. Components are bugled by restraining the blank in a die bearing the desired shape and applying an internal hydrostatic pressure to the tube via a liquid or solid medium. But hot bulge forming utilizes the difference of linear expansion coefficient between components and dies. The research on hot bugle forming is limited. However, due to the complexities involved in the deformation process, conventional analytical studies were able to provide only very limited knowledge on hot bulge forming. Finite element analysis is a very powerful technique to study complex metal forming process. Simulations can give valuable information about component dimension, shape, temperature and stress every time. A 2-D thermo-mechanical coupled elastic-plastic finite element model was developed. In this model, nonlinear radiation heat transfer and thermal physical properties of material depending on temperature were considered. This paper carried out numerical simulation of hot bulge forming of BT20 titanium alloy cylindrical workpiece in vacuum by using finite element software MSC.Marc. The temperature field, deformation field and stress field of hot bulge forming of BT20 titanium alloy cylindrical workpiece was calculated, and the corresponding experiments were carried out. The simulated results agree well with the experimental results. This work lays a theoretical foundation for vacuum hot bulge forming process.