Hot deformation behavior and globularization mechanism of Ti-6Al-4V-0.1B alloy with lamellar microstructure

Hot deformation behavior and globularization mechanism of Ti-6Al-4V-0.1B alloy with lamellar microstructure were quantitatively studied through isothermal compression tests with the temperature range of 850-950 A degrees C and strain rate range of 0.01-1.00 s(-1). The results show that the peak flow stress and steady stress are sensitive to the strain rate and temperature. The value of deformation activation energy is 890.49 kJ center dot mol(-1) in (alpha A + beta) region. Dynamic recrystallization is the major deformation mechanism. Flow softening is dominated by dynamic recrystallization at 850-950 A degrees C. TiB particles promote the recrystallization of alpha laths. Globularization processes consist of four steps: formation of subgrain after dynamic recovery in alpha plates; subgrain boundary migration caused by alpha/beta interfacial instability; interfacial migration promoting beta phase wedge into alpha phase; disintegrating of alpha laths by diffusion processes; and grain-boundary sliding. Globularization mechanisms during hot deformation processes of the Ti-6Al-4V-0.1B alloy with lamellar structure are continuous dynamic recrystallization.