Features of Duplex Microstructural Evolution and Mechanical Behavior in the Titanium Alloy Processed by Equal‐Channel Angular Pressing.

Abstract

This report describes a study of the regularities in the kinetics of microstructure evolution and recrystallization processes in the Ti–5.7Al–3.8Mo–1.2Zr–1.3Sn alloy (Russian analogue VT8M‐1) during processing by equal‐channel angular pressing (ECAP). To produce a duplex (globular‐lamellar) structure, the billets are subjected to preliminary heat treatment, including water‐quenching from a temperature below the β‐transus followed by annealing at 700 °С. For the ECAP temperature selection, the deformation behavior of the alloy with a duplex structure is investigated under upsetting in the temperature range of 650–800 °С. The evolution of the globular and lamellar fractions is examined during ECAP processing, and an emphasis is placed on the role of phase transformations, dynamic recrystallization, and spheroidization of the α‐phase which is realized with increasing accumulated strain when processing by ECAP. It is demonstrated that after 6 ECAP passes an equiaxed ultrafine‐grained structure is formed with a mean α‐phase grain/subgrain size of ≈0.6 μm. The investigation includes an examination of the effect of microstructure on the mechanical properties of the alloy.