Experimental Study And Molecular Dynamics Simulation On Hot Tensile Of TC4 Titanium Alloy

TC4 titanium alloy which has the characteristics of high strength,low density,excellent corrosion resistance and so on,is widely used in aerospace,shipbuilding,automotive and other fields.TC4 titanium alloy is a dual-phase alloy composed of ?-phase and ?-phase,and its macro-mechanical properties are related to the microscopic deformation behavior of ?-phase and ?-phase.However,it is difficult to measure the microscopic deformation mechanical properties of ? and ? phases by experimental methods.Therefore,the micro-deformation behavior of ?-phase and ?-phase in TC4 titanium alloy is simulated by using molecular dynamics method to reveal the TC4 titanium alloy thermal deformation mechanism on the basis of measuring the thermal deformation behavior of TC4 titanium alloy in this paper.TC4 titanium alloy is taken as the research object in this paper and the strain-stress curves of TC4 titanium alloy at different temperatures and different strain rates are also measured.Through data post-processing,the effects of temperature and strain rate on the mechanical properties of TC4 titanium alloy such as elastic modulus,yield strength,tensile strength and elongation can be clearly analyzed.The thermal deformation microstructure and fracture morphology of TC4 titanium alloy were observed and analyzed by using metallographic technology,XRD,SEM and so on.The molecular dynamics simulation of the micro-deformation behavior of TC4 titanium alloy was carried out with LAMMPS software.The ?-phase and ?-phase in TC4 titanium alloy were modeled separately,and the ?-phase and ?-phase were subjected to tensile simulation according to the above-mentioned thermal deformation parameters.Visualization software OVITO was used to analyze the crystal structure and dislocations in the model changes.The experimental results show that the tensile strength and yield strength decrease continuously with the increase of temperature,while the plasticity increases when the TC4 titanium alloy is thermal-stretching at different temperatures.The microstructure changes from the initial equiaxed grains to the two-state structure and the grain size becomes larger,at the same time.The number of fracture morphology dimples are added and its size becomes larger with the temperature increasing.At different strain rates,the tensile strength increases as the strain rate increases,while the elongation increases as the strain rate decreases.Different strain rates have negligible effect on the microstructure,but high strain rates will elongate the grains.The simulation results show that the changes in the mechanical properties of ? and ?phases obtained during the hot stretching process,which is consistent with the macroscopic experiments,and the yield strength and tensile strength continue decreasing with the increase of temperature.During the thermal deformation of the atomic configuration,stacking faults and twinning occur,the plasticity of the ? phase is better than the ? phase.