Effect of Repetitive Bending and Straightening Process on Microstructure Properties and Deformation Mechanism of a Ti–Al–Cr–Mo Alloy

In this research, a repetitive bending and straightening process was carried out on the Ti-3Al-4Cr-Mo alloy for 20 passes. The changes in mechanical properties of the titanium alloy before and after repetitive bending and annealing were studied. The microstructure evolution and deformation mechanism were analyzed. The results show that after the repetitive bending and straightening process, the microstructure of the Ti-3Al-4Cr-Mo alloy is obviously refined, and, simultaneously, the yield strength is significantly improved. After annealing at 850 °C, the plastic ductility of the material was improved. The combined effects of grain refinement and dislocation behavior were the main reasons for the improvement in mechanical properties of the Ti-3Al-4Cr-Mo alloy. Twinning rarely occurred during plastic deformation of the Ti-3Al-4Cr-Mo alloy. The fine grains strongly inhibited the formation of twins. In addition, a small amount of α to β phase transformation was observed during the repetitive bending and straightening process of the material, which may have been induced by strain accumulation.