The as cast matrix structure of vermicular iron is characterized by high ferrite content (40% ~ 50% or higher), but pearlite stabilizing elements (such as copper, tin, antimony, etc.) can also be added to obtain as cast pearlite matrix with a content of about 70%. Pearlite matrix can also be obtained by normalizing treatment.
(1) The carbon equivalent of vermicular iron is high. After adding rare earth alloy, the molten iron is purified, so it has better fluidity. When the carbon equivalent is the same, the fluidity of vermicular iron and gray cast iron is similar.
(2) The shrinkage of vermicular iron is also between gray cast iron and nodular iron. The gating system can be designed according to gray cast iron. However, for complex castings with high compactness and large wall thickness difference, the pouring and feeding system of nodular iron should be adopted.
(3) Vermicular iron has good properties of both gray cast iron and nodular iron. Its tensile strength and yield strength are higher than that of gray cast iron, which is equivalent to ferritic nodular iron. The thermal conductivity is close to that of gray cast iron, so the casting process is convenient, simple and high yield.
(4) Vermicular iron has good growth resistance and oxidation resistance. The wear resistance of vermicular iron is more than 2.2 times that of Chinese standard HT300, twice that of high phosphorus cast iron, and is similar to that of phosphorus copper titanium cast iron.