Study On Hot Deformation Behavior And Microstructure Evolution About A Kind High Temperature Titanium Alloy

TA12 titanium alloy is a nearly alpha type alloy improved base on the alloy of Ti-5.5Al-4Sn-2Zr-1Mo-0.25Si-1Nb in the early days in institute of Chinese academy of sciences, it can be used under the environment of up temperature to 550 ℃ because of its excellent thermal stability, and it is widely applied in the manufacture of aircraft engine compressor disk, blade, etc.The paper uses the Gleeble-3800 thermal/mechanical testing machine with high temperature single-pass hot compression experiment on TA12 titanium alloy,explored the hot deformation behavior of TA12 titanium alloy under the condition that the strain temperature at 870 ~ 1030 ℃, the strain rate is 0.01 ~ 10 s- 1 and 70%of engineering strain. The flow stress constitutive equation of TA12 titanium alloy was established based on the hyperbolic sine function relationship and the mechanism research of the microstructure evolution of TA12 alloy during hot deformation was carried out by the dynamic materials model processing figure. For another, explored the different heat treatment system on the influence of the alloy at room temperature mechanical properties and microstructure. Get the following important conclusions:(1) Through the exploration by the ways of calculation method, thermal expansion method and continuous heating metallurgical phase method of phase transition temperature of this batch TA12 titanium alloys, get this batch TA12 titanium alloys of different phase transition temperature is about 1005 ℃.(2) Analyzed the impact of thermal processing deformation parameter on Ti-5.4Al-3.7Sn-3.0Zr-0.7Mo-0.45Nb-0.29Si-0.4Ta alloy under the condition that high temperature deformation flow stress, also studied the alloy microstructure evolution law with the hot deformation parameter changes, the results showed that:the high temperature deformation flow stress increases with the increasing strain rate and the decreasing strain temperature; the influence of deformation temperatureon the alloy of alpha phase morphology and amount of change, strain rate effect of deformation on the time.(3) By using hyperbolic sine function relation form to build and through linear regression to obtain TA12 titanium alloy flow stress constitutive equation and flow stress constitutive equation represented by Z parameters:(4) The TA12 titanium alloy processing figure was established Based on dynamic material model(DDM), thus get the best of the batch TA12 titanium alloy thermal processing region: 910 ~ 970 ℃, 0.01 ~ 0.3 s-1.(5) The influence of The solid solution temperature and aging time on the TA12 titanium alloy was studied,the results show that: in the experimental parameters of the temperature range, with the increase of solid solution treatment temperature, alloy tensile strength increases,but the elongation decreases.