Recrystallization Behavior of TA2 Pure Titanium Containing Lamellar α Phase in Microstructure

Low room temperature strength is an important factor limiting the engineering application of TA2 pure titanium, and fine grain strengthening is a key mechanism to improve the strength of TA2. The purpose of the research is to introduce the lamellar α-phase into the TA2 microstructure by single-phase zone heat treatment, followed by its recrystallization by cold rolling and annealing, and then analyze its recrystallization behavior and its effect on tensile strength.The results show that the recrystallized grain size of TA2 can be controlled within 10 μm after cooling at 910 ℃ for 1 h, 80% cold rolling and 600 ℃ annealing. The microstructure comparison shows that the microstructure morphology before cold rolling has an important influence on the recrystallization behavior of TA2. The lamellar α phase in the microstructure bends and fractures during the cold rolling process, and more recrystallization nucleation sites can be formed during the subsequent annealing, leading to better grain refinement. Compared with the original microstructure without lamellar α-phase, the Weiss microstructure specimens forming after holding furnace cooling in the single-phase zone can increase the yield strength by about 40 MPa after cold rolling +600 ℃ annealing, while the plasticity remains largely unchanged.