Formation of slip bands and microstructure evolution of Ti-5Al-5Mo-5V-3Cr-0.5Fe alloy during warm deformation process

The characteristics of slip band and its interplay with dynamic precipitation of a phase during the thermo-mechanical coupling process in titanium alloy is really interesting but is not sufficiently ascertain. In the present work, the formation of slip bands, dynamic microstructure evolution and crystallographic orientation relationship during warm deformation of Ti-5553 alloy were investigated using Scanning Electron Microscopy/Transmission Electron Microscopy/crystallographic calculations. Results reveal that multiple-slip bands with two or three different propagating directions would form during the warm compression. These three distinctly oriented bands could be estimated as slip bands of (112)[11 (1) over bar], (1 (23) over bar) [1 (1) over bar1] and ((2) over bar 13)[1 (1) over bar1] types. Nano/ultrafine-trimorphic structure (lamellar alpha, equiaxed alpha and irregular alpha) formed dynamically during the warm deformation process due to the dynamic interplay between the initiation of the slip bands and the nucleation of alpha phase. There is an obvious competitive mechanism between dynamic recovery/dynamic recrystallization and alpha phase nucleation, which depended on the deformation parameters and modes. These results could provide valuable reference for process optimization and the microstructural evolution controlling. (C) 2018 Elsevier B.V. All rights reserved.