Development of Ti-6Al-4V sheet with low temperature superplastic properties

摘要

A Ti-6Al-4V alloy sheet with a submicrocrystalline structure (grain size of 0.3 μm) was produced by multistep isothermal forging followed by flat rolling at temperatures below 650℃. The sheet showed a very strong basal texture and isotropic properties in the sheet plane. Room temperature yield strength, ultimate tensile strength, and fatigue limit of the sheet were 1.2-1.3 times higher than that of sheet with micron-sized grains. Sheet with the submicrocrystalline structure showed superplastic properties at temperatures 650-750℃. A complex hollow structure was produced from the sheet by diffusion bonding/superplastic forming at temperatures 750-800℃. The structure had high microstructural homogeneity and high quality of diffusion bonding.