한국주조공학회

The effects of minor additives on the casting properties of AC4A aluminum alloys were investigated. Measurements of the cooling curve and microstructure observations were conducted to analyze the effects of Ti-B and Sr minor elements during the solidification process. A fine grain size and an increase in the crystallization temperature for the α-Al solution were evident after the addition of 0.1wt% Al-5%Ti-1%B additive. The modification effect of the eutectic Mg2Si phase with the addition of 0.05% Al-10%Sr additive was prominent. A fine eutectic Mg2Si p phase and a decrease in the growth temperature of the eutectic Mg2Si phase were evident. Fluidity, shrinkage and solidification-cracking tests were conducted to evaluate the castability of the alloy. The 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 10%Sr additives showed the maximum filling length owing to the effect of the fine α 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 the Al-10%Sr additive. The tendency of the occurrence of solidification cracking decreased owing to the effect of the fine α-Al grains and the modification of the Mg2Si phase with the combined addition of Al-5%Ti-1%B and Al-10%Sr additives.

Grain refinement, Eutectic Mg2Si modification, Fluidity test, Shrinkage test, Solidification-cracking test, AC4A aluminum alloy