Microstructure Simulation Of Free Forgings Process For Pure Titanium

Commercially pure titanium is a kind of material with low density, high strengthand corrosion resistance. It is widely used in aerospace, shipbuilding and otherindustries. With the development of computer technology, to reduce the productioncost, the numerical simulation technology is applied to metal forming process.Therefore, it is necessary to study forging process simulation of industrial puretitanium.In order to perform numerical simulation and design the properly free forgingprocess parameters of commercially pure titanium TA1, the flow stress behavior of thismaterial was researched by Gleeble-1500D thermal simulation test machine. The strainrates were0.01s-1,0.1s-1,1s-1and5s-1. The deformation temperatures were700℃,800℃,900℃and950℃. The maximum deformation degreewas0.7. Themicrostructure of pure titanium after high temperature compression deformation wasobserved by optical electron microscope.The experiment results show that the dynamic recovery and recrystallizationoccur during hot temperature compression test of commercially pure titanium TA1.The flow stress is increased with the decrease of deformation temperature and isdecreased with the decrease of strain rate. Commercially pure titanium TA1is softenedeasily at low strain rate and high temperature. The thermal deformation activationenergy (Q) and hyperbolic sine Arrhenius constitutive equation of commercially puretitanium TA1are got by this experiment. It is reasonable to use work hardening ratemethod to study material recrystallization critical strain. Recrystallization criticalstrain decreases with the rise of temperature and the decrease of deformation rate whendynamic recrystallization occurs.Commercially pure titanium Cellular Automata model was got by calculation oftrue stress-strain data from the experiment and the analysis of material microstructureafter deformation. The microstructure evolution process of industrial pure titanium was simulated by Deform-3D software, and the simulation results were compared with themicrostructure acquired by hot temperature compression test. The results show that,dislocation density increases at the beginning of deformation and then it decreases.Material internal microstructure comes up with dynamic recovery and recrystallizationduring the deformation process. The simulation results of dynamic recrystallizationgrain fit well with the experimental results, which indicates the established CA modelis reasonable.The above model was imported in Deform-3D finite element numericalsimulation software, and the stretching and upsetting process of pure titanium largeforgings was simulated by software. The simulation results show that, therecrystallization degree of pure titanium is increased by stretching and upsettingprocess. The original as-cast organization is improved and turned into forging stateorganization. Based on simulation results, the reasonable process is designed.