Cr 과 Be 을 복합 첨가한 자동차 차체재료용 Al-Mg-Si 합금의 도장소부경화성 개선에 관한 연구 = Transformations;A study on the improvement of bake hardenability in Al-Mg-Si alloy with Cr and Be for auto body materials

다국어 초록 (Multilingual Abstract)

Al-Mg-Si system alloys are capable of providing a good combination of formability and paint bake response. which has favored with automotive panel applications. Be is a useful element to improve the bake hardenability in Al-Mg-Si alloy. Two step aging and RRA(retrogression and reaging) are very useful to increase the bake hardenability in Al-Mg-Si system alloys. Cr is also known to increase strength and the bake hardenability in Al-Mg-Si system alloys. In this paper, the effects of Be and Cr addition, two-step aging and RRA treatment on the bake hardenability in Al-Mg-Si-Be-Cr alloys are investigated by hardness, tensile test, and differential scanning calorimetry. Age hardening is accelerated and bake hardening is ameliorated by the addition of Be and Cr in Al-Mg-Si alloy. The bake hardening is improved by preaged at 60℃ and 150℃ followed by baked at 180℃ for 30 minutes in Al-Mg-Si-Be-Cr alloy rather than Al-Mg-Si alloy. And the bake hardening is also improved by RRA(150℃/20min→225℃/3min→180℃/30min) treatment in Al-Mg-Si and Al-Mg-Si-Be-Cr alloys.