Ti-6Al-4V sheet cooled from α + β region at different rates: Specific microstructural, textural characteristics and hardness

A hot-rolled Ti-6Al-4V (Ti-64) annealed in α + β phase field was cooled in water, air and furnace (WC, AC and FC, respectively). Their microstructural and textural characteristics were subjected to dedicated characterization and correlated with hardness changes. There exist primary bulk α (α p ) grains and transformed secondary α (α s ) plates in both WC and AC specimens. FC specimen mainly comprises residual β phase and coarser equiaxed α p grains with no α s plates. Compared to the initial texture, the maximum textural intensity of WC specimen is slightly increased while it gradually decreases at lower cooling rates along with intensified recrystallization component. Reasons for reduced hardness of annealed specimens are attributed to reduced low-angle angle boundary density and recrystallization-promoted grain growth.