Research On FEM Numerical Simulation Of TC6 Titanium Alloy Forging Process

TC6 titanium alloy is a two phases titanium alloy and provided with complex microstructure. However it has many properties such as low consistency, high intensity and resist corrosion, TC6 titanium is too expensive to use widely and hard to be deformed. At the present time, the researches on TC6 titanium alloy forging process are not sufficient and systematic, but the need of TC6 titanium alloy is increasing rapidly. The microstructures and properties of titanium alloy are sensitive to forging thermomechanical parameters, which leads to narrow range of the forging thermomechanical parameters. Thus, each aspect of the titanium alloy forging process must be so strictly controlled that products with specified microstructures and properties can be obtained. The traditional ways such as the trial-and-error and empirical method to define the process window of titanium alloy cannot keep pace with the rapid developing modern industry.The interaction between the microstructure and constitutive relationship or thermomechanical parameters is pre-requisite information for the thorough study of material deformation. Based on the experimental results of isothermal constant strain rate compression test, a new constitutive relationship is established by using the nonlinear regression method. The constitutive relationship formulation is capable of revealing the dynamical characteristics of the TC6 titanium alloy during hot deformation processes, which offers an essential prerequisite for improvement of numerical simulation precision of metal forming processes. Based on the thorough study of the key technological problems of rigid-plastic FEM simulation, a 3D FEM simulation of the isothermal forging process and normal die forging processes of TC6 titanium alloy disc has been carried out with different thermomechanical parameters (temperature, velocity and friction), and also the influence of these deformation technological parameters on equivalent strain, stress and load-journey curves has been studied.The forging processes and thermomechanical parameters will decide the final microstructure of workpiece. The employed performance of components is decided by the final microstructure. Based on a Yada model, a computation of the grain size of aTC6 titanium alloy disc during the isothermal forging has been carried out by using the rigid-plastic FEM with different thermomechanical parameters (temperature, velocity and friction), and the influence of these deformation technological parameters on grain size has been studied.