Influence on texture on beta grain growth during continuous annealing of Ti–6Al–4V

The kinetics of grain growth during continuous beta annealing of two different lots of Ti–6Al–4V bar stock with an equiaxed–alpha preform microstructure were determined using an induction-heating technique. Heating rates of 1.4, 5.6, and 18°C s−1 and peak temperatures between 1020 and 1260°C were utilized. Noticeable differences were found in the grain-growth behaviors of the two lots of material with one exhibiting much smaller grain sizes than the other for a given set of processing conditions. A semi-quantitative analysis of the results revealed that the two batches of alloy had similar grain-growth exponents and activation energies but different rate constants. These trends were explained in terms of the beta-phase textures in the as-received materials which persisted during beta annealing. The former material had a moderate strength, cube-like texture, whereas the latter lot of material exhibited a very strong and sharper fiber texture. The grain-growth results were thus explained in terms of the effect of texture on grain-boundary surface energy/mobility.