一种新型β钛合金Ti-34521高温变形过程中微观组织演变机制

Thermal simulation compression experiment of a new type of β titanium alloy Ti-34521 was carried out by using a Gleeble-3500 thermal simulation compression tester under the deformation condition of strain rates of 0.1-30 s^-1, deformation temperature of 750-1000 ℃ and height reduction of 50%, and microstructure of the alloy after deformation was characterized by optical microscope and electron backscatter diffraction (EBSD) technique in order to study the microstructure evolution mechanism of the alloy during the high temperature deformation. The results show that the β grains of the alloy after deformation are elongated along the direction perpendicular to compression, and the deformed <001> and <111> fiber texture is formed. The increase of deformation temperature and the decrease of strain rate promote the dynamic recovery (DRV) and dynamic recrystallization (DRX) of the β grains, and the grain boundary bulging and the generation of DRX grains make the β grain boundaries show the serrated and necklace-like morphology. Finally, the relationship between microstructure evolution and mechanical behavior of the alloy is discussed, and it is found that when the strain increases to 0.4, the apparent deformation activation energy of the alloy is 221.533-201.207 kJ/mol, which is similar to the self-diffusion activation energy of β-Ti, becasue the dynamic recovery is the main dynamic softening mechanism in the deformation process of the alloy.