Microstructure/texture evolution maps to optimize hot deformation process of near-α titanium alloy

Abstract

The microstructure/texture evolution (MTE, for short) map and processing map of a new near α titanium alloy Ti65 were constructed in order to investigate the workability and microstructure evolution of hot deformation. The processing map illustrated four domains, two summit domains and two instability domains. The morphologies of the α phase changed from the spheroidization (α+β region) to the deformed and elongated β grains (near the β transus temperature Tβ), and then to the obvious dynamic recrystallization (DRX) (β region) with the temperature rising from 930 °C to 1140 °C. Deformation in the α+β field mainly generated the texture component with [0001] or [022‾3] parallel to radial directions (RDs). While deformation in the β phase field formed two types of texture component with [0001] parallel to RDs and [21‾1‾0] parallel to compression direction. An optimized processing map was summarized by overlaying the macro-instability map on the original processing map, and the instability domain of Ti65 alloy was confirmed in the area with the strain rate higher than 0.01 s−1.