AUTHOR=Liu Chao , Wang Xin , Zhou Ge , Li Feng , Zhang Siqian , Zhang Haoyu , Chen Lijia , Liu Haijian TITLE=Dislocation-Controlled Low-Temperature Superplastic Deformation of Ti-6Al-4V Alloy JOURNAL=Frontiers in Materials VOLUME=7 YEAR=2021 URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2020.606092 DOI=10.3389/fmats.2020.606092 ISSN=2296-8016 ABSTRACT=

The superplastic tension and deformation mechanism of Ti-6Al-4V alloy at 923 K and a tensile speed of 10−3, 5 × 10−3, or 5 × 10−2 s−1 was studied on an AG 250KNE electronic tension tester. Through theoretical modeling, the unit dislocation count of this alloy during superplastic deformation was introduced into the Ruano–Wadsworth–Sherby (R-W-S) deformation mechanism map, and a new deformation mechanism map involving dislocation count was plotted. Thereby, the mechanism underling the low-temperature superplastic deformation of this alloy was predicted. It was found the superplastic tension of Ti-6Al-4V at the tested temperature was controlled by dislocation movement, and with an increase in strain rate, the deformation transited from the dislocation-controlled mechanism with a stress index of 4 to the dislocation glide mechanism with a stress index of 5 or 7. At the strain rate of 10−3 s−1, this alloy reached the largest tension rate of 790% and strain rate sensitivity index of 0.52 and had excellent low-temperature superplastic properties.