| 학회 |
한국재료학회 |
| 학술대회 |
2019년 봄 (05/15 ~ 05/17, 평창 알펜시아 리조트) |
| 권호 |
25권 1호 |
| 발표분야 |
특별심포지엄8. 미래자동차 경량화를 위한 알루미늄합금 개발 및 공정 기술-오거나이저:이성희(목포대) |
| 제목 |
Die Quenching of Age-Hardenable Aluminum Alloy Billet on Servo Press with Die Motion Control |
| 초록 |
Die quenching of the age-hardenable AA2024 aluminum alloy billets was carried out on a 450kN servo press with ram-motion control of WC-20mass%Co dies directly after solution heat treatment (SHT). To clarify the dependence on billet volume for die quenching, two billets with a height of h0 = 8 mm or 16 mm and with the same diameter of 16 mm were prepared. The cylindrical billets were heated in an electric furnace at 823 K and transferred to the press. Then, the billets were uniaxially compressed with a reduction in height (Δh/h0) of 2% or 5%, and further held between the dies. The sandwiching duration by dies (td.q.) was varied from 0 to 8 s. Based a measured temperature change, hardness and TG–DTA analysis, it is found that die quenching is successfully carried out without precipitation hardening only in the case of the billet with a height of 8 mm and td.q. ＞ 6 s. However, the reduction in height is limited less than 5% by intergranular fracture on side surface of billet during the die quenching process. In order to enhance the deformability in single operation, the two-step die motion is proposed. A cylindrical billet was heated to 823K and transferred to the press. Then, the billet was uniaxially compressed with Δh/h0 = 5%, and further held between the dies for cooling. After sandwiching for 8 s, the billet with a height of h1 = 7.6mm was further compressed with a reduction in height (Δh/h1) of 2 or 5% at lower temperature. The die quenching process with the two-step die motion leads to increase the total reduction in height to 10%. It is confirmed that super-saturated solid solution successfully formed at the 1st step is maintained in the 2nd step. It is found that the peak hardness of the two-step processed billet is higher than that of the one-step processed billet, and that the precipitation kinetics in artificial aging is accelerated by the two-step motion. |
| 저자 |
전재열, 김철우, 유효상, 김정한, 조균택, 조재익
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| 소속 |
한국생산기술(연) |
| 키워드 |
die quenching; AA2024; precipitation; servo press; two-step die motion; strain aging
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| E-Mail |
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