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

Abstract:

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 α phases are slightly deformed and β phase experiences dynamic recovery and dynamic recrystallization during 750 oC rolling; whereas lamellar α phase is nearly distributed in parallel, some of which are partly fragmentized, and β phase merely undergoes dynamic recovery. Texture intensity of α phase increases remarkably in lamellar structure but slightly in equiaxed structure, while texture intensity of β 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 °C, texture intensities of α and β phase both decrease and the anisotropy of mechanical properties significantly decreases.

Key words:Ti-55511 alloy;dynamic recovery;dynamic recrystallization;microstructure evolution;texture