Microstructure Evolution And Numerical Simulation Of Tc11 Alloy During Compressive Deformation In β Phase

As a kind of titanium alloy with good mechanical properties, TC11 alloy is aα+βdual-phase titanium alloy with the phase transition temperature between 998-1020℃. Because of its excellent heat resistance such as high-temperature strength and creep resistance, it becomes an ideal material to make parts of aero-engine, and has been successfully used in the manufacture of aerospace engine compressor disk, blades and other parts. In order to mass production of acceptable quality TC11 titanium alloy forging, this paper studied the microstructure evolution mechanism inβphase during compressive deformation, and optimized parameters of the cogging forging process. It provides the theoretical basis for grain refinement. The main study contents and achievements are as follows:Firstly, stress-strain behavior curves were studied by thermal simulation compression tests and effect laws of hot deformation parameters. Then based on dynamic materials model, the processing maps for deformation of TC11 alloy inβphase was established. Combined with microstructure observation, microstructure evolution mechanisms of TC11 alloys during deformation were analyzed and concluded.Secondly, hot deformation activation energy of TC11 alloy in P phase is calculated using the modified ARRHENIUS function. It's close to the self-diffusion activation energy of the titanium alloy inβphase that shows that the thermal deformation during theβphase is mainly controlled by diffusion of the dislocation glide and the climb process. Recrystallization mechanism of both continuous dynamic recrystallization and discontinuous dynamic recrystallization was found by the TEM. Then, constitutive equation of the TC11 alloy inβphase during compressive deformation was established using Zener-Hollomon parameter, as well as the recrystallization grain size d. Recrystallization kinetics model was built using classic phenomenological A VRAMI-type equation. Finally, the finite element model of the TC11 alloy inβphase during compressive deformation was built. On the basis of the DEFORM, this paper conducted a secondary program development of user subroutines which includes both recrystallization grain size model and kinetics model. The microstructure evolution inβphase during compressive deformation was simulation, and the optimized cogging forging process parameters has been obtained.