Dynamic fragmentation and spheroidization of α phase grains during hot deformation of Ti-6Al-4V alloy: Paper presented at the “XIII Scientific Conference on Titanium and Titanium Alloys 2017”, 24–27 September 2017, Janów Podlaski, Poland

Abstract Development of mechanical properties of titanium alloys is usually achieved by the control of their microstructure (globular, lamellar, bimodal). Dynamic fragmentation and spheroidization of elongated α phase grains, formed from martensite laths, in the microstructure of Ti-6Al-4V alloy are considered in the paper. The effects of α phase grain spheroidization was evaluated in tensile tests over a temperature range of 800–900°C and strain rate range of 10−3–10−2 s−1. Completed spheroidization of elongated α phase grains and subsequent growth of equiaxed grains for all deformation modes were found. A low value of apparent activation energy for deformation was calculated – suggesting grain boundary sliding was the main deformation mechanism. The results showed good correlation with the kinetic rate equation based on the Zener–Hollomon parameter.