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 degreesC s(-1) and peak temperatures between 1020 and 1260 degreesC 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. (C) 2001 Elsevier Science B.V. All rights reserved.