Generally speaking, nodular cast iron manhole cover is rarely rusted, but once this phenomenon occurs, we need to remove rust, so how to carry out rust removal, this article will give you a simple explanation.
At present, there are two kinds of derusting methods for nodular cast iron manhole cover, one is jet derusting, the other is spray derusting. There is a gap between the two. The so-called shot rust removal is mainly to use the impeller blade of shot blasting machine to disperse Abrasives onto the surface of nodular cast iron well cover, and remove the rust and dirt on the surface by collision.
Spray derusting is that the compressed air after oil-water separation will spray the abrasive from the nozzle at a high speed, and the grinding powder will collide with the surface of ductile iron well cover to remove rust by pressure。 For the correct rust removal method of nodular cast iron well cover, we can simply explain this。 When we encounter this situation, we can choose one of the above two methods。
1. Compared with cast iron, ductile iron has advantages in strength. The tensile strength of ductile iron is 60K, while that of cast iron is only 31k.
2. The yield strength of ductile iron is 40K, but the cast iron does not show yield strength, and fracture occurs eventually. The strength cost ratio of ductile iron is much better than that of cast iron.
3。 The strength of ductile iron is comparable to that of cast steel。 The yield strength of nodular cast iron is 40 K, while that of cast steel is only 36 K。 In most municipal applications, such as water, brine, steam, etc。, the corrosion resistance and oxidation resistance of ductile iron are better than that of cast steel。
4. Because of the spheroidal graphite microstructure of nodular cast iron, nodular cast iron is better than cast steel in reducing vibration capacity, so it is more conducive to reduce stress.
An important reason for choosing ductile iron is that the cost of ductile iron is lower than that of cast steel。 The low maintenance cost of cast iron manhole cover makes this material more popular, with higher casting efficiency and less machining cost of nodular cast iron
5。 The low carbon content in cast steel makes the carbon existing as free graphite will not form structural sheet。 The natural form of carbon in cast iron is free graphite sheet。
6. After the pressure load parts of nodular cast iron are treated by ferrite annealing cycle, the spherical structure in ductile iron can also eliminate the crack phenomenon easily produced by flake graphite in the cast iron.
7. In the micrograph of nodular cast iron, it can be seen that the crack ends after the graphite ball. In the ductile iron industry, these graphite balls are called "crack terminators.".
The above is the right way to remove rust and the advantages of nodular cast iron manhole cover. Welcome to purchase.