| Abstract |
| Ti-15V-3Cr-3Sn-3Al (Ti-15-3) alloy was cold-deformed by flow forming for manufacturing a seamless tube component. The cold-deformed Ti-15-3 alloy was subjected to heat treatment employing an intermediate recovery annealing at 650℃~750℃ and subsequent aging at 500℃ in order to achieve a good combination of tensile strength and ductility. An increase in the amount of cold deformation led to an increase in tensile strength and a decrease in ductility, because of elongated, severely deformed β-grain structure. Direct aging formed fine aggregates of α-precipitates which had the Burgers orientation relationship with β matrix. Further increase in tensile strength occurred after direct aging only, but it caused a significant decrease in ductility to ~3%. An intermediate recovery annealing at 700℃, followed by aging treatment retained a higher ductility of ~10%, with a moderate increase in tensile strength. Very fine β recrystallized grains and sub-grains were formed by an intermediate recovery annealing, and their boundaries provided a preferential nucleation site of α-precipitates during subsequent aging. The uniformly distributed, randomly oriented a-precipitates promoted the improvement of strength-ductility balance. |
|
|
| Key Words |
| Ti-15V-3Cr-3Sn-3Al, Cold flow forming, Recovery, Aging, Precipitation |
|
|
 |
|
