Microstructure Evolution and Mechanical Properties of Ti-55511 Alloy with Equiaxed and Lamellar Microstructures During Hot Rolling and Annealing

The equiaxed and lamellar microstructures of T-55511 alloy were obtained by different heat treatment routes. Microstructure evolution and mechanical properties of Ti-55511 alloy with equiaxed and lamellar microstructures during hot rolling and annealing were investigated by SEM, EBSD, TEM and tensile tests. The results show that equiaxed alpha phases are slightly deformed and beta phase experiences dynamic recovery and dynamic recrystallization during 750 degrees C rolling; whereas lamellar alpha phase is nearly distributed in parallel, some of which are partly fragmentized, and beta phase merely undergoes dynamic recovery. Texture intensity of alpha phase increases remarkably in lamellar structure but slightly in equiaxed structure, while texture intensity of beta phase decreases both in equiaxed and lamellar structure. In addition, the anisotropy of equiaxed structure is small while that of lamellar structure is obvious. When the rolled lamellar structure is annealed at 600 degrees C, texture intensities of alpha and beta phase both decrease and the anisotropy of mechanical properties significantly decreases.