Why are ductile iron manhole covers so popular?

Shuttle through the streets and alleys of the city, manhole covers can be seen everywhere, and you may not notice it at ordinary times, only when it is damaged and hinders you, you will take a look at it. Although the small manhole cover is inconspicuous, it plays an essential role in urban sewage, water supply, power supply and other pipelines. In the past, manhole covers were basically made of concrete, but now most of them are made of a metal called ductile iron, because this material is lighter than concrete and has better strength performance, so it is widely used . So, do you know why ductile iron manhole covers are so popular?

Understand what is ductile iron, it is actually a kind of cast iron. During the solidification process of molten iron, by adding nodulizers and inoculants, the precipitated graphite is spherical in shape. Since spherical graphite has little effect on the matrix splitting and stress concentration, its performance is higher than that of conventional cast iron.

1. Ductile iron manhole cover has good performance

The specifications of the ductile manhole cover and the general manhole cover are the same, but the material is different. By comparing the chemical composition and physical performance data of the two materials, it is concluded that the material of the ductile manhole cover is much higher than the general manhole cover in terms of tensile strength, elongation, yield strength and ultimate load pressure head. The content is much more reasonable than ordinary manhole covers.

2. Good beautification effect

Under the premise of ensuring flatness, the manhole cover is integrated into the road surface and the road to become an integration to achieve the effect of beautifying the city. However, the old-fashioned manhole covers in the past have a dark gray color and a rough appearance. The concrete well ring must be exposed. The color of the asphalt surface layer is inconsistent with the asphalt surface layer. Therefore, the ductile manhole cover has conquered the urban construction personnel with its obvious characteristics of light weight, high strength, good toughness, corrosion resistance, fatigue resistance, and reasonable cost.

3. Light weight and high strength

Compared with gray cast iron and malleable cast iron, nodular cast iron has more excellent strength, toughness and plasticity, and its performance can be further improved by heat treatment. Therefore, the weight of ductile iron manhole covers is 30-40% lighter than that of gray cast iron. Compared with cast steel, ductile iron has the strength close to that of cast steel, even higher yield strength, and has better performance in corrosion resistance, shock absorption, casting and cutting performance.

4. Low manufacturing cost

Due to the spherical graphite microstructure of ductile iron, ductile iron is superior to cast steel in terms of vibration dampening ability, so it is more conducive to reducing stress. An important reason for choosing ductile iron is that ductile iron is cheaper than cast steel. The low cost of ductile iron makes the material more popular, casting more efficiently and reducing the machining cost of ductile iron manhole covers.