Microstructure, texture, mean free path of dislocations and mechanical properties of Ti–6Al–4V alloy during uniaxial compression at elevated temperatures

In the present work, microstructure, texture, mean free path of dislocations and mechanical properties of Ti–6Al–4V (Ti64) alloy during uniaxial compression testing has been studied in the temperature range of 298 K–873 K. Significant deformation twins were observed in the samples beyond 20% reductions at temperatures of 298 K and 673 K only. Such twins were further found to be of non-Schmid type and were confirmed through VPSC (Visco-plastic self-consistent) simulation. The deformation bands were observed at all studied temperatures in the grains of specific orientations. These deformation bands were found to nucleate at the grain boundaries and gradually progressed towards the interior of the parent grains. The deformation bands facilitated the origination of deformation twins inside the grains, i.e. at the boundary between deformation band and a parent grain. Bulk texture measurements showed that the texture strength of (0001) pole increased up to 30% reduction at all temperatures of deformation. However, the dominant texture strength remained along (12‾10) pole, i.e. the initial texture of the sample before subjected to uniaxial compression. An initial decrease and subsequent increase in hardening rate was observed in the samples deformed at room temperature. The maximum decrease in the rate of hardening was observed at a temperature of 673 K and up to 18% strain followed by a relative increase thereafter. Further, the observed decrease in the rate of hardening was found to be relatively lower at a temperature of 873 K compared to that at 673 K. The Ti64 alloy showed better strength compared to that of the commercially pure (CP) titanium samples tested in the similar temperature range of 298 K–873 K which can be attributed to the dominant dislocation-solute interaction in the former case.