한국주조공학회

The aim of this research is to investigate the effects of gas bubbles on the formation of spheroidal graphite in cast iron, Fe-Si-8%Mg alloy, mischmetal hydride(MmH_2) and CaCO_3, which discharge various amounts of Mg, H_2 and Co_2, gases, were added to Fe-3.9% C-2.0%Si melt and the melt was innoculated with 0.3wt% of 75%Fe-Si. The spheroidal graphites and/or compacted vermicular graphites were produced with more than 0.625cc/g of Mg gas or more than 0.3125cc/g of H_2 gas while CO_2 gas did not contribute to graphite spheroidization. Nodule counts increased with the amount of Fe-Si-Mg added ; but they decreased with the amount of MmH_2 added because the number of effective gas bubbles decrease with the increase in Mm residual. The bull's eye structure was revealed with 0.625cc/g, 1.25cc/g of Mg and 0.3125cc/g of H_2 ; the ledeburite structure was revealed with more than 0.625cc/g of $H_2$ 수식 이미지.