Microstructural adjustments and tensile properties of a hot-forged Ti−22Al−23Nb−3V−Y alloy

Abstract

Microstructures and tensile properties of a hot forged Ti−22Al−23Nb−3V−Y alloy were investigated systematically. Different heat treatments were performed to adjust the wrought microstructure to optimize tensile properties. It was found that features of O phase precipitates and its volume fraction was rather sensitive to the cooling rate after the solution. The volume fraction of primary lamellar O phase increased from 19.65% by solution treatment to 36.30% by annealing with furnace cooling and up to 100% by annealing with a controlled slow cooling rate of 1 °C/min. Meanwhile, the width of the lamellar secondary O phase increased. Fine acicular second O phase contributed to strengthening, while the coarsen primary ones were favorable to the ductility. The solution & aging treated microstructure exhibited a good tensile strength of 1100 MPa and an acceptable ductility of 8% at room temperature, by contrast, annealing at 950 °C with a controlled slow cooling rate gave rise to a higher elongation of 12%, but a relatively low strength of 960 MPa.