Ductile iron manhole cover is mainly made of ductile iron, and the quality of this manhole cover is related to the spheroidization rate. Rust-proof asphalt paint is commonly used to treat castings, and of course, the surface of nodular cast iron manhole cover is also sprayed with rust-proof asphalt paint. One advantage of nodular cast iron manhole covers is that they are about 30% lighter than similar gray cast iron manhole covers due to their high strength and toughness. Features of nodular cast iron manhole cover: good toughness. The impact value of medium carbon steel is more than 10 times that of gray cast iron. Strong corrosion resistance. The water spray corrosion test shows that the corrosion amount in 90 days is only 1/40 of steel pipe and110 of gray cast iron pipe. The service life is twice that of gray iron pipe and five times that of ordinary steel pipe. Good plasticity. The elongation is ≥7%, which is similar to that of high carbon steel, and the elongation of gray cast iron is zero.
High strength. The tensile strength is ≥ 420mpa, and the yield strength is ≥ 300mpa, which is the same as that of low carbon steel and three times that of gray cast iron. Because nodular cast iron has the microstructure of spherical graphite, it is better than cast steel in reducing vibration, so it is more conducive to reducing stress. An important reason for choosing ductile iron is that the cost of ductile iron is lower than that of cast steel. The low cost of nodular cast iron makes this material more popular, with higher casting efficiency and lower processing cost. The strength of nodular cast iron is equivalent to that of cast steel. The yield strength of ductile iron is relatively high, with the lowest yield strength of 40k, while that of cast steel is only 36k. In most municipal applications, such as water, salt water, steam, etc. The corrosion resistance and oxidation resistance of nodular cast iron exceed that of cast steel.