Mechanism of texture and microstructure evolution during warm rolling of Ti-6Al-4V alloy

Ti-6Al-4V (Ti64) plates were subjected to rolling at 600 degrees C and 800 degrees C, respectively, for reductions up to 90% reduction in thickness. The mechanism of texture and microstructure evolution during rolling was studied in the present study. Extension twins of coherent nature were observed in the samples rolled up to 50% of reduction. The deformation was relatively inhomogeneous in the samples rolled at 600 degrees C compared to that at 800 degrees C. Visco-plastic self-consistent (VPSC) simulation showed that relative activity of pyramidal slip <c+a> was higher during rolling at 800 degrees C compared to that at 600 degrees C. The average activity of slip systems per grain was less than five for the samples rolled at 600 degrees C and this might be responsible for the strain heterogeneity in the large grains. Further, twinning activity was found to be limited to a true strain of 0.5, as supported by the microstructural observation. VPSC simulation also showed the presence of contraction twins in the samples which was further supported by X-ray texture measurement. Dominant basal texture was observed in the samples irrespective of the temperature of rolling.