The Study On Hot Deformation And Dynamic Recrystallization Behavior Of Ti-5322 Titanium Alloy

The hot compressive experiment of Ti-5322 titanium alloy was carried out on Gleeble-3500 thermo-simulation machine.The research of the thermal Deformation behavior of the alloy under the Deformation temperature(900?1050?),Deformation rate(0.01?1s^-1)and maximum strain of 60%.Use the OM and SEM to explore the evolution of high temperature microstructure during thermal simulation,and reveal the nucleation mode of DRX.This experiment provides theoretical support for the optimization of single-phase Deformation process of Ti-5322 titanium alloy.The main innovation points and conclusions of this paper are as follows:The analysis of true stress-strain curve shows that the flow stress increases with the increase of Deformation rate and the decrease of heating temperature.Based on the experimental data,the high temperature constitutive model of Ti-5322 titanium alloy was established.The value of Q=189.39KJ/mol was obtained by calculation,and the calculated Q value is greater than the self-diffusion activation energy,which indicates that the mechanism of the alloy during Deformation is mainly the slip and climb of dislocations.At the same time,empirical calculations show that the maximum error between the predicted peak value and the measured value obtained by the constitutive equation is 11.6%,and the average error is 4.03%,which indicated that the equation could accurately describe the influence of different experimental parameters on the flow stress value of Ti-5322 titanium alloy in the process of thermal Deformation.According to the flow stress curve and the principle of thermodynamic irreversibility,the peak stress(s_p),critical stress(s_c),peak strain(?_p)and critical strain(?_c)for dynamic recrystallization of Ti-5322 titanium alloy are obtained,and the critical strain(?_c)is determined at the same time.The critical strain and dynamic recrystallization volume fraction model of Ti-5322 titanium alloy during thermal simulation.Through the analysis of the thermal simulation data and microstructure under different experimental parameters,it can be obtained that the critical strain will decline with the reduce of the Deformation rate and the rise of the Deformation temperature.In addition,the DRX volume fraction will increase with the increase of Deformation temperature and Deformation under certain Deformation conditions.Combined with OM and SEM images,it can be seen that dynamic recrystallization is the main softening mechanism of Ti-5322 titanium alloy during hot Deformation,the nucleation of DRX of the alloy first appears at the grain boundary of the original grain,DDRX dominated by the bulging of the original grain boundaries is the main nucleation mechanism during hot Deformation.The flow stress model and DRX fraction model of Ti-5322 titanium alloy during hot Deformation were simulated by Deform software.The simulation results show that the stress and strain distribution of the alloy is regional during the compression process.The distribution of stress and strain in the center of the workpiece is quite different from that in other regions,and changes with the change of Deformation conditions.DRX occurs first in the easily Deformable area in the center of the workpiece,and complete DRX occurs in the central area as the amount of Deformation increases.Under certain Deformation conditions,the increase of Deformation temperature will increase the progress of DRX.