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How much is the price of the manhole cover?

Anti-theft covers are very common, and its range of application is also very extensive, cast iron covers prices have been deeply concerned about consumers. Here comes to introduce specific content.
Containing a carbon fiber cast iron manhole cover material in the carbon fiber with high strength, high modulus, high temperature resistance, electrical conductivity and a series of performance, the first widely used in the field of aerospace, in recent years in the sports equipment and sports activities are widely used. It is predicted that industrial grade carbon fibers will be widely used in the fields of civil engineering, construction, transportation, automobile and energy.
The price of cast iron covers has dropped somewhat recently, because the overall level of China's carbon fiber is still relatively low, which is equivalent to the mid and late stage of foreign countries in 70s, and the gap with foreign countries is about 20 years. The main problems of domestic carbon fiber are unstable performance, large coefficient of dispersion, no high performance carbon fiber, single variety, incomplete specifications, continuous length, no surface treatment and high price.
The main processing method of cast iron well covers is that the core can be used. For example, the engine block, whether it is cast iron or cast aluminium, can not be replaced by external processing methods. If an external machining method is used to process a cylinder, the price of a car may be required. Second, reuse. More than 50% of the earth's resources have been used, and the importance of re utilization will increase day by day.
Manhole cover is also called ductile iron manhole cover is a kind of nodular cast iron, nodular cast iron by spheroidization and inoculation by spherical graphite, effectively improve the mechanical properties of cast iron, especially the plasticity and toughness increased, resulting in higher than the strength of carbon steel. Ductile iron is a kind of high strength cast iron material developed in 50s twentieth Century, its comprehensive performance is close to the steel, it is based on its excellent performance, has been successfully used in casting complex stress, strength, toughness and wear resistance requirements of the higher parts. Nodular cast iron has developed rapidly to be second only to grey cast iron and widely used as cast iron material. The so-called "iron instead of steel", mainly refers to ductile iron.
Nodular cast iron composition
Pig iron is an alloy of iron and carbon carbon content more than 2%, pig iron carbon content is generally in 2.5%--4%, including C, SI, and Mn, S, P and other elements, is the use of iron ores in blast furnace smelting products. According to the different form of carbon in pig iron, it can be divided into several kinds, such as steelmaking pig iron, casting pig iron and nodular cast iron. Cast iron with spherical graphite. The splitting action of spherical graphite on metal matrix is smaller than that of flake graphite, so that the strength of cast iron reaches 70 to 90% of the matrix strength, and the tensile strength is up to 120kgf/mm2, and it has good toughness. Ductile iron in addition to iron, the chemical composition is usually: carbon content of 3.6 ~ 3.8%, containing silicon 2 ~ 3%, including manganese, phosphorus, sulfur, total amount of not more than 1.5%, and the appropriate amount of rare earth, magnesium and other agents.
Two. Properties and manufacturing process of ductile iron
Ductile iron castings almost in all major industrial sectors applied in these sectors require high strength, ductility, toughness, wear resistance, thermal and mechanical shock, severe high temperature or low temperature, corrosion resistance and dimensional stability. To meet these changes in use conditions, ductile iron has many brands, providing a wide range of mechanical properties and finishing properties. Most ductile iron castings, such as those specified in the international organization for Standardization (ISO1083), are produced mainly in Unalloyed form. Obviously, this range includes tensile strength greater than 800 Newtons / mm, and a high strength grade of elongation of 2%. The other extreme is the high plasticity grade, whose elongation is greater than 17%, while the corresponding strength is lower (minimum 370 Newton / mm spoon). Strength and elongation are not the only root of the designer's choice of materials, while other decisive important properties include yield strength, modulus of elasticity, abrasion resistance and fatigue strength, hardness and impact properties. In addition, corrosion resistance and oxidation resistance as well as electromagnetic properties may be critical for designers. In order to meet these special uses, a group of Austenitic Ductile iron has been developed, which is usually called "Ni Resis". These Austenitic Ductile iron are mainly alloyed with zinc, chromium and manganese, and are listed in international standards. The production process (a) the strict requirements of chemical composition, the content of silicon in molten iron requirements than the original carbon gray cast iron, nodular cast iron in reduced manganese, phosphorus, sulfur content (two) of liquid iron tapping temperature higher than the gray cast iron, to compensate for the ball, loss of liquid iron temperature inoculation when (three) for spheroidizing treatment, that is to add liquid iron spheroidizing agent (four) adding inoculant inoculation (five) nodular cast iron with poor fluidity, shrinkage, therefore require higher pouring temperature and larger size of the gating system, reasonable application of riser, cold iron, sequential solidification principle (six) heat treatment
Three. Production history and application of ductile iron
Unearthed in iron smelting sites in Henan Gongxian Tieshenggou in West Hanzhoung, in the late iron, through metallographic examination, spheroidal graphite having radiating, spheroidization rate is equivalent to the modern standard level. Modern ductile iron was developed abroad only later than 1947. In ancient China the iron, silicon content is low in a fairly long period of time, that is to say, in the period of the Western Han Dynasty about 2000 years ago, China's iron spheroidal graphite, has through annealing soften low silicon iron castings obtained by. This is a great achievement of the ancient cast iron technology in China, and also a miracle in the history of metallurgy in the world.
Nodular cast iron, with

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