Hot Deformation Behavior And Processing Map Of Ti-17 Alloy

Ti-17 alloy has already become one of the most popular materials in the field of aviation because of its good mechanical properties.At the same time,Ti-17 alloy is very sensitive to the hot deformation parameters,which makes its plastic deformation difficult and the products are more likely to have defects.Therefore,the present work is to conduct isothermal compression tests with a constant strain rate on Ti-17 alloy with Gleeble-3800 thermal simulation equipment,to establish DMM dynamic material model thermal processing map,and to conduct in-depth study on the high temperature compressive behavior of Ti-17 alloy.This work is essential to the determination of optimal hot deformation parameters in actual industrial processes.The detailed work is as follows.Firstly,the true stress-true strain curve of Ti-17 alloy was drawn by using origin software based on the data obtained from the hot compression experiments,and the curves were corrected twice by considering additional dead zone and friction.The flow behavior of Ti-17 alloy in the hot compression process is analyzed to be related to the hardening and softening mechanism.The results show that the flow stress of Ti-17 alloy is negatively correlated with temperature and positively correlated with strain rate.The degree of dynamic recrystallization increases significantly with the decrease of the deformation temperature.Secondly,the Arrhenius-type hyperbolic sinusoidal equation and the temperaturecompensated strain rate factor "Z-H" are used to describe the relationship between the flow stress and the deformation parameters of Ti-17 alloy based on the data obtained from the hot compression experiments,and then to obtain the heat deformation activation energy Q of Ti-17 alloy.The predictive constitutive equation of Ti-17 alloy based on the strain compensation was obtained by fitting the relevant material constants with sixth degree polynomial,and the predictive constitutive equation was verified by the correlation coefficient(R)and the absolute value of the average relative error(AARE).Finally,according to the DMM dynamic material model and the Prasad rheological instability criterion,the thermal processing maps of Ti-17 alloy at the strain of 0.1～0.6were established.The results of the thermal processing maps show that the rheological instability zone of Ti-17 alloy mainly appears in the region of higher strain rate.