| Title |
Effects of Thermomechanical Treatment on Microstructure and Tensile Properties of Ti-15V-3Cr-3Sn-3A1 Alloy |
| Authors |
장성호(Seong Ho Jang); 이갑호(Kap Ho Lee); 백경호(Kyeong Ho Baik) |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Ti-15V-3Cr-3Sn-3Al; Cold flow forming; Recovery; Aging; Precipitation |
| 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. |