Characterization of hot deformation behavior of Ti–3Al–5Mo–4.5V alloy with a martensitic starting microstructure

Abstract

The hot deformation behavior of Ti–3Al–5Mo–4.5V alloy with an [Formula: see text] martensitic microstructure was studied in the temperature range of 700–1000[Formula: see text]C and strain rates range of 0.001–[Formula: see text] up to a height reduction of 50%. The results show that an ultrafine equiaxed microstructure with an average grain size of [Formula: see text] were successfully produced through thermomechanical processing of a martensitic starting microstructure. A processing map was successfully constructed and provides appropriate processing parameters for hot deformation which are located in the temperature range of 700–800[Formula: see text]C and the low strain rate range of 0.001–[Formula: see text]. The instability domain mainly occurs at the strain rate higher than [Formula: see text] for the whole deformation temperature, which should be avoided during practice. The flow softening mechanism of the alloy is determined to be continuous dynamic recrystallization and the unstable flow is caused by the macro-fracture and flow localization.