재활용 AC4A 알루미늄 합금의 주조특성에 미치는 Al-5wt%Ti-1wt%B, Al-10wt%Sr 첨가제의 영향

Abstract

Abstract

The effects of minor additives on casting properties were investigated in AC4A aluminum alloys. Measurements of the cooling curve and microstructure observations were performed to analyze the effects of (Ti-B), Sr elements during the solidification process. Fine grain size and an increase of the crystallization temperature for α-Al solution were evident with the addition of 0.1wt% Al-5%Ti-1%B additive. The modification effect of the eutectic Si phase with the addition of 0.05% Al-10%Sr additive was prominent. A fine eutectic Si phase and a decrease in the growth temperature of the eutectic Si phase were evident. Fluidity, shrinkage and solidification-cracking tests were conducted to evaluate the castability of the alloy. Combined addition of Al-5%Ti-1%B and Al-10%Sr additives showed the maximum filling length owing to the effect of the fine α-Al grains. The macro shrinkage ratio increased, while the micro shrinkage ratio decreased with the combined addition of Al-5%Ti-1%B and Al-10%Sr additives. The macro shrinkage ratio was nearly identical, while the micro shrinkage ratio increased with the addition of Al-10%Sr additive. The tendency of solidification-cracking occurrence decreased owing to the effect of the fine α-Al grains and the modification of Si phase with the combined addition of Al-5%Ti-1%B and Al-10%Sr additives.