What is the scope of application of cast iron manhole covers? Here is an introduction to the scope of application of the cast iron manhole cover and its point classification:
Cast iron manhole cover is a kind of widely used manhole cover. Today I will tell you the scope of its use, as follows:
1. Iron-carbon alloy with carbon content above 2%. Industrial cast iron generally contains 2% to 4% carbon
Carbon mostly exists in the form of graphite in cast iron, sometimes in the form of cementite.
In addition to carbon, cast iron also contains 1% to 3% silicon, as well as elements such as manganese, phosphorus, and sulfur.
Alloy cast iron also contains elements such as nickel, chromium, molybdenum, aluminum, copper, boron, and vanadium. Carbon and silicon are the main elements that affect the microstructure and properties of cast iron
cast iron can be divided into:
①Gray cast iron. The carbon content is relatively high (2.7% to 4.0%). The carbon mainly exists in the form of flake graphite with a gray fracture surface, referred to as gray iron.
②White cast iron. The content of carbon and silicon is low, and the carbon mainly exists in the form of cementite, and the fracture is silvery white.
③ Malleable cast iron. Obtained from white cast iron after annealing treatment, graphite is distributed in clusters, referred to as tough iron.
④Nodular cast iron. Gray cast iron molten iron is obtained after spheroidizing treatment, and the precipitated graphite is spherical, referred to as ductile iron.
⑤Vermicular graphite cast iron. The gray cast iron molten iron is obtained after vermicularization treatment, and the precipitated graphite is worm-like.
⑥Alloy cast iron. Ordinary cast iron is obtained by adding appropriate amount of alloying elements (such as silicon, manganese, phosphorus, nickel, chromium, molybdenum, copper, aluminum, boron, vanadium, tin, etc.).
3. The effect of overheating and high temperature standing of cast iron
1. In a fixed temperature range, increasing the overheating temperature of molten iron and prolonging the high-temperature standing time will result in the refinement of the graphite matrix structure in the cast iron and increase the strength of the cast iron.
2. Increase the degree of superheat and reduce the nucleation ability of cast iron. As a result, the morphology of graphite becomes worse, and even free infiltration occurs, which reduces the strength, so there is a ‘critical temperature’.
3. The critical temperature mainly depends on the chemical composition of the molten iron and the cooling rate of the casting. It is generally believed that the critical temperature of ordinary gray cast iron is about 15001550℃, so it is always hoped that the iron tapping temperature is higher
Widely used in drainage engineering, used in rainwater and sewage pipelines, as sewage manhole covers, rainwater manhole covers, and drainage manhole covers.
二 It is widely used in water supply engineering. The thickness of ductile iron manhole cover is used for tap water, fire protection engineering, water meter box cover, etc. It is also the tap water manhole cover, fire manhole cover and water meter cover that we often see.
三 Widely used in heating engineering, used in thermal pipelines, that is, we often see thermal manhole covers, gas manhole covers, etc.
4 Widely used in power supply projects, used in power supply cables, telecommunications projects, telephones, communication cable pipelines, that is, we often see electric manhole covers, communication manhole covers.
5 Widely used in garden engineering, used in supporting induction pipelines, that is, stainless steel manhole covers, invisible manhole covers and grass basin manhole covers that we often see.
6 Widely used in gas engineering, gas engineering, natural gas pipelines, etc., which is the gas manhole cover we often see.
七 Widely used in street lamp engineering, used in power supply, lighting, cable pipelines, which is the street lamp manhole cover we come all year round
The above is the scope of application of cast iron manhole covers and its classification has some influence
