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Detailed explanation of nodular cast iron manhole cover

Dec. 18, 2019

Ductile iron manhole covers are a type of ductile iron products. Spheroidal graphite is obtained by spheroidizing and inoculating treatment, which effectively improves the mechanical properties of cast iron, especially plasticity and toughness, so as to obtain higher strength than carbon steel. Ductile iron is a high-strength cast iron material developed in the 1950s. Its comprehensive performance is close to that of steel. It is based on its excellent properties that it has been successfully used to cast some complex forces, strength, toughness and wear resistance. Highly demanding parts. Ductile iron has rapidly developed into a cast iron material that is widely used after gray cast iron. The so-called "steel instead of steel" mainly refers to ductile iron.

Ductile iron manhole covers are generally divided into circular and square. In urban road administration, circular is generally used because circular manhole covers are not easy to tilt and can better protect the safety of pedestrians and vehicles. The use of circular is mainly considered that the length of each diameter of the circular manhole cover through its center is the same, so if the manhole cover is rolled up by the passing vehicle, because the diameter will be slightly larger than the wellhead below Wide, the manhole cover will not fall into the wellhead.

If a square is used, because the diagonal of the square is obviously longer than the length of each side, when such a aluminum manhole covers is rolled up, it is easy to fall into the well along the diagonal direction of the wellhead, causing hidden dangers. If the wellhead is made round or significantly smaller than the well cover, the square well cover will not fall into the well. This involves a question of the maximum utilization and economy of materials. The use of the manhole cover depends on the size of the wellhead. If a square manhole cover with an area much larger than the wellhead has to be installed on it, the use and practical value of the material is naturally more effective than using a round manhole cover directly. Ensure the safety of the wellhead.

In the countryside and cable wells, squares are generally used, which can better prevent the entry of liquids such as rainwater.

Ductile Iron Manhole Covers

Ductile Iron Manhole Covers


Pig iron is an iron-carbon alloy with a carbon content of more than 2%. Industrial pig iron generally has a carbon content of 2.5% -4%, and contains elements such as C, SI, Mn, S, and P. It is smelted by iron ore in a blast furnace. product. According to the different forms of carbon in pig iron, it can be divided into steelmaking pig iron, cast pig iron and ductile iron.

The precipitated graphite is spherical cast iron. Spheroidal graphite has a smaller cracking effect on the metal substrate than flake graphite, making the strength of cast iron reach 70 to 90% of the strength of the matrix structure, the tensile strength can reach 120kgf / mm2, and it has good toughness. The chemical composition of nodular cast iron from custom cast iron bench leg factory other than iron is usually: carbon content of 3.6 to 3.8%, silicon content of 2.0 to 3.0%, manganese, phosphorus, sulfur total content of not more than 1.5%, and appropriate amounts of rare earth, magnesium and other nodulizing agents.