TC21 titanium alloy is a high-strength, high toughness, and high damage tolerance titanium alloy with good strength, plastic fracture toughness, and low crack propagation rate. The microstructure of TC21 titanium alloy determines its usability and mechanical properties. Through deformation and heat treatment, its microstructure can be effectively improved, thereby achieving better performance. The superplastic forming technology of titanium alloys is a technology developed by utilizing the excellent deformation properties of materials in superplastic states. When titanium alloy is in a superplastic state, its flowability is good, it is easy to fill, and thus it is easy to form complex qualified parts. Unlike the ordinary forged microstructure, the deformation zone of the sample after superplastic deformation exhibits significant dynamic recrystallization, resulting in a significantly coarsened microstructure and affecting its properties. Nanchang University of Aeronautics and Astronautics, in collaboration with AVIC Jiangxi Jinghang Aviation Forging and Casting Co., Ltd., conducted heat treatment on TC21 titanium alloy after superplastic deformation to study its microstructure evolution law, providing reference for the development of isothermal forging and superplastic precision forging processes for this alloy.

The superplastic tensile test is conducted using SANS-CMT4104 microcomputer controlled electronic universal testing machine, with a sample size of 5mm × A 15mm standard tensile specimen is heated and insulated by a resistance furnace. After superplastic tensile deformation under different conditions, TC21 titanium alloy was subjected to dual annealing heat treatment to study the effect of hot working process on the microstructure evolution of TC21 titanium alloy. The results show that when the deformation temperature is between 890 and 960 ℃, the elongation of TC21 titanium alloy first increases and then decreases with the increase of deformation temperature, and the optimal superplastic deformation temperature is 910 ℃; TC21 titanium alloy α+β Superplastic deformation in the phase zone, and then α+β After dual annealing treatment in the phase zone, a bimodal structure is obtained; In quasi β Perform superplastic deformation α+β After dual annealing treatment in the phase zone, the net basket structure is obtained.