Microstructural evolution and mechanical properties of ultrafine-grained Ti fabricated by cryorolling and subsequent annealing

Ultrafine-grained (UFG) commercial purity titanium (CP Ti) has a significant potential for use in medical implants and aerospace structural parts. Herein, UFG CP Ti sheets are processed by cryorolling and room-temperature rolling (RTR), respectively, followed by annealing for 1 h at temperatures from 250 to 350 °C. The grain size is reduced from ≈75 μm to ≈85 and ≈220 nm after cryorolling and RTR, respectively. The results show that the curves of tensile stress versus engineering failure strain for samples subjected to cryorolling and subsequent annealing are above those for samples subjected to RTR and subsequent annealing. In addition, the curves of ultimate tensile stress × fracture elongation versus grain size after cryorolling and annealing are above those for RTR and annealing. It is demonstrated that a combination of cryorolling and annealing leads to improved toughness compared with the processing by RTR and annealing.