| 박판주조법으로 제조한 Al-0.6Mg-1.2Si 합금판재의 소부경화특성 |
| 주기철1,2, 이윤수1, 김민석1, 김형욱1,3, 김양도2 |
1재료연구소 금속재료연구본부 경량금속연구실
2부산대학교 재료공학부
3과학기술연합대학원대학교 신소재공학과 |
| Bake-hardening Properties of Al-0.6Mg-1.2Si Alloy Sheets Fabricated by Twin Roll Casting |
| Gi-Cheol Ju1,2, Yun-Soo Lee1, Min-Seok Kim1, Hyoung-Wook Kim1,3, Yang-Do Kim2 |
1Metallic Materials Division, Korea Institute of Materials Science (KIMS), Changwon 51508, Republic of Korea
2Department of Materials Science and Engineering, Pusan National University, Busan 46241, Republic of Korea
3Department of Advanced Materials Engineering, Korea University of Science and Technology(UST), Daejeon 34113, Republic of Korea |
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Received: 10 July 2017; Accepted: 15 September 2017. Published online: 4 December 2017. |
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| ABSTRACT |
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The effect of pre-aging treatment on the microstructure and mechanical properties of Al-0.6Mg-1.2Si aluminum alloy sheets fabricated by twin roll casting (TRC) was investigated. It was observed that two kinds of nanoclusters, cluster(1) and cluster(2), play an important role in the bake-hardening properties of Al-Mg-Si aluminum alloy. The hardness of the TRC Al-0.6Mg-1.2Si alloy sheets was continuously increased up to 48 h by natural-aging, and the highest yield strength value was about 146 MPa. The yield strength was 280 MPa after bake-hardening at 180 ℃ for 30 min immediately after quenching, whereas the yield strength was 172 MPa when natural-aging proceeded for about 1 week before bake-hardening. This result is due to fact that cluster(1) is formed during natural-aging at room temperature and has detrimental effects on bake-hardening. On the other hand, when pre-aged at 150 ℃ for 10 min, cluster(2) predominantly formed and promoted the precipitation of β″ phase. The yield strength was 256 MPa after bake-hardening, which indicates that the pre-aging treatment is an effective method, and also depresses the negative effects of natural-aging and promotes β″ precipitation. The Al-Mg-Si aluminum alloy sheets fabricated by twin roll casting method exhibited mechanical properties equal to or higher than those of the direct-chill (DC) casting sheets despite the simplified manufacturing process. |
| Keywords:
aluminium, twin roll casting, bake-hardening, yield strength, precipitation |
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