The fluidity of molten iron depends on carbon equivalent and pouring temperature, but has nothing to do with the shape of graphite. Under the same carbon equivalent, there is no significant difference in fluidity between flake graphite, vermicular graphite and spheroidal graphite cast iron. However, the carbon equivalent of vermicular graphite cast iron is higher, and its strength is higher than that of high strength gray iron with low carbon equivalent. Therefore, under the same tensile strength, the fluidity of vermicular graphite cast iron is much higher than that of gray iron.

Table 4-9 and figure 4-6 show the test results of fluidity of various cast irons. Archimedes spiral sample is used to measure the fluidity and wet mold casting is used. It can be seen from the table that even if the pouring temperature of Ma steel pipe is slightly lower than that of alloy cast iron, its fluidity is far greater than that of alloy cast iron, while the pouring temperature of Maanshan Steel pipe is not much different from that of nodular cast iron, so is their fluidity.