| Industrial pure titanium has a high specific strength,excellent corrosion resistance and excellent machinability,and is an attractive structural material.Due to the importance of titanium in its field of application,the control of the organization and properties of titanium materials is more demanding.Fully understanding the deformation behavior and microstructure of pure titanium is the basis for the design and manufacture of titanium technology,and it can also obtain good strength and plasticity matching through annealing.To this end,this paper has carried out basic research on the thermal deformation behavior,rolling and heat treatment process of TA1 pure titanium,and selected suitable thermal processing parameters.The main conclusions are:The rheological curve of TA1 pure titanium was obtained by a single pass thermal simulation experiment.The flow stress increased with the decrease of temperature and the increase of strain rate.The constitutive model of Nangang and the hyperbolic sinusoidal constitutive model are established.Among them,the hyperbolic sinusoidal constitutive model can accurately predict the deformation resistance of TA1 pure titanium.The established flow stress model is:the fitted value is 0.975,and the average error is6.37%.The deformation activation energy of TA1 pure titanium is calculated to be316.22k J/mol.The thermal processing map based on dynamic material model is constructed and combined with the microstructure under different deformation conditions.The optimal deformation process parameters of TA1 pure titanium is determined as follows:deformation temperature is from 700℃ to 750℃ and the strain rate is from 10s-1 to 20 s-1.Through the double pass thermal simulation experiment,it is concluded that the softening rate of TA1 pure titanium increases with the increase of deformation temperature and residence time between passes.When the deformation temperature is850℃ and the residence time between the passes is 60 s,the softening rate is maximized.Through the research of rolling and annealing process,it is determined that the microstructure and properties of TA1 pure titanium are better than those under other conditions when the rolling temperature is 840℃,the deformation degree is 70%,and the cooling mode is air cooling.As the annealing temperature increases,the shorter the time to complete recrystallization,the crystal grains gradually grow up,and the recrystallization is almost completed at 650℃;with the extension of the annealing time,the recrystallization nucleation and growth rate of TA1 pure titanium is accelerated,and the organization is evenly distributed.When the deformation amount was determined to be 70%,the optimum annealing parameter was 650℃×45 min. |
