Microstructural evolution of a Ti–6Al–4V alloy during thermomechanical processing

Variation of microstructure of a Ti–6A1–4V alloy during thermomechanical processing at a range of hot working conditions (temperature: 850–1050 °C, strain rate: 0–1.0 s−1 has been investigated for further understanding and control of the processing–structure–property relationships. The influences of hot working parameters on deformation localization, width of α platelets, (α→β) phase transformation, and (meta)dynamic recrystallization were systematically examined by optical microscopy and scanning electron microscopy. The experimental results showed that the lamellar morphology of the α phase can be sub-divided into five different categories for samples processed in the (α+β) phase field, and these represent three stages of the (α→β) phase transformation. It was also noted that a certain degree of the (α→β) phase transformation occurred concurrently with the mechanical deformation in the (α+β) phase field. The experimental evidence suggests that dynamic and/or metadynamic recrystallization has occurred in the β phase field, but was not involved in the (α+β) phase field under the experimental conditions.