The effect of microstructure and phase composition of Ti–6Al–4V titanium alloy hardened surface layer on its mechanical properties

The microstructure, phase composition of Ti–6Al–4V alloy specimens subjected to ultrasonic impact treatment and scanning electron beam treatment as well as their deformation behavior under uniaxial tension were investigated. After the ultrasonic impact treatment nanocrystalline α-grains in the surface layer was found. Scanning electron beam treatment leads to formation of acicular α′-phase in the primary β-phase grains. Dislocation glide, twinning and shear banding mechanisms were revealed in scanning electron beam treated Ti–6Al–4V titanium alloy specimens under tension. Formation of nanocrystalline α-phase in the surface layer was due to the strong localization of plastic deformation from the beginning of loading.