| Title |
Effect of Nb Content on the Precipitation Hardening Behavior of Alloy 718 |
| Authors |
최병학(Byung Hak Choe); 안형준(Hyung Joon Ahn); 신평우(Pyung Woo Shin); 박노광(Nho Kwang Park) |
| Abstract |
Homogenization treatments were performed at 1200℃ on cast Alloy 718 and its Nb modified version in order to investigate the effects of alloy chemistry and homogenization treatment on age-hardening behavior. Regardless of alloy chemistry, age hardening occurs faster at 1200℃/1hr than at 1200℃/10hrs condition. The remaining Laves phase affects the age-hardening behavior through the control of γ˝ precipitation. The larger volume fraction and even distribution of Laves phases, containing high Nb content, enhance the formation of γ˝ near the Laves phases. A peak hardness was accordingly obtained only after 8hrs of aging at 720℃ in the sample homogenized at 1200℃/1hr. This peak time is in contrast to 28hrs of aging in the sample homogenized ac 1200℃/10hrs. The Laves phase and γ˝ precipitates in the aged alloys were identified with electron microscopy. |