Eutectic solidification type of spheroidal graphite cast iron and flake graphite cast iron are very different, especially in hyper-eutectic composition alloy, the former is the severe mushy type but the latter is not so. CRF value of spheroidal graphite cast iron is 20∼30, but it is only about 5∼6 in flake graphite cast iron; the former being 5∼6 times larger than the latter. CRF expresses the degree of mushiness and skin type.