Research On Numerical Simulation Of TC21 Titanium Alloy Forging Technology

TC21 is a high-strength, high-toughness and damage tolerant (α+β) two phase titanium alloy. It has widespread prospect in aviation, spaceflight and automobile industries. Forging is one of the main manufacturing methods for titanium alloy structural parts and it can result in great variation of microstructures and performance under different forging conditions, so the research on forging technologies is of great significance. So based on the correlative experiment, this paper systematically investigated the hot compression characteristics of TC21 titanium alloy and the deformation behavior of a large forging piece by finite element method in order to provide theory and guidance for the actual hot mold forge. The main results of this dissertation are as follows:Firstly, the rigid-viscoplastic FEM theories are studied systematically and the stress-strain relationship at constant strain rates and temperatures was obtained through hot deformation experiment with Gleeble-3500 simulator. Based on the experiment, an isothermal compression FEM model for TC21 titanium alloy was established and the effect of different technological parameters on the deformation process and load-stroke curves was obtained by the numerical simulation.Secondly, the FEM analysis of a large forging at non-isothermal forging conditions was carried out. And the distribution rules of the equivalent strain, equivalent stress and temperatures have been obtained at various deformation velocities, deformation temperatures, friction factors and die temperatures. Meanwhile, the influence of various deformation parameters on the load-stroke curves is analyzed. The simulation results have already been applied to the forging of a TC21 titanium alloy aircraft frame successfully.Lastly, the characteristic section of the large TC21 frame forging was predicted with the Yada microstructure prediction model. The grain size distribution has been acquired under different deformation parameters. Through analysis of the results, the influence of various deformation parameters on grain size distribution has been found out.