Hot Deformation Behavior And Microstructure Evolution Of TA2

Industrial pure titanium of TA2 is an attractive material widely used in a range of industrial fields with its excellent properties,such as high strength,good plasticity,corrosion resistance and weld ability.It can be selected for high temperature applications,such as aviation,aerospace and aircraft structural parts,petrochemicals,etc.As a result,more and more higher requirements are imposed on its forming technology.An accurate study of the deformation behavior and microstructure is the basis for the process design and produce of TA2,and the desired matching strength and plasticity can be achieved by heat treatment to produce materials with excellent comprehensive properties.In this paper,the hot deformation behavior and microstructure evolution of industrial pure titanium TA2 were studied by thermal simulation compression experiment and combined with microstructure observation.The effect of different parameters on deformation is analyzed by the true stress-strain curve.The constitutive equations were established based on the Arrhenius model,the Johnson Cook model,the modified Johnson Cook model and the modified Zerilli-Armstrong model.The hot processing map was constructed based on the dynamic material model,and the characteristics of deformation microstructure was analyzed.The laboratory hot rolling application was carried out to obtain the optimum hot processing parameters and heat treatment process parameters of TA2.The following results are obtained:The main factors affecting the flow stress of TA2 are deformation temperature and strain rate,and the degree of deformation is less affected,with positive strain rate sensitivity.By calculating and comparing the constitutive equations of the four models,it can be concluded that the Arrhenius equation has the high prediction accuracy for the flow stress of the material,the theoretical value and the predicted value have the good fitting.The error analysis of R value and AARE values in the experimental temperature range is 0.938 and 9.49%,respectively.The hot processing map of TA2 based on DMM is drawn.The optimum deformation process parameters of TA2 range from 740°C to800°C,and the strain rate is 12s^-1 to 20s^-1.The hot rolling process of TA2 was experimentally verified under different deformation parameters.It was found that the optimum hot rolling process parameters were heating temperature 870℃,rolling temperature 760°C,reduction of 70%and air cooling.Meanwhile,it can be obtained the best strength and plasticity matching by the heat treatment at 660°C×30 min,with uniform polygonal equiaxedαgrain and the tensile strength 459.514 MPa,yield strength336.327 MPa,elongation 39.6%.