It is a ductile covers ductile iron products, ductile spherical graphite obtained through ball and inoculation, effectively improving the mechanical properties of cast iron, in particular, to improve the ductility and toughness, resulting in higher than carbon steel strength. Ductile iron is the 1950s developed a high-strength cast iron, its overall performance is close to steel, is based on its excellent performance, has been successfully used to cast a number of complex stress, strength, toughness, wear require a higher part. Ductile iron has quickly become second only to gray cast iron, cast iron material is widely used. The so-called "iron and steel", mainly referring to ductile iron.

Manhole covers are generally divided into round and square, in the city of Highways in general, circular, because a circular covers easy to tilt, pedestrians and can better protect the safety of the vehicle. Circular, mainly on account of its center by a circular covers the length of each diameter are the same, so if the covers are rolled from passing vehicles, because no matter how rolling onwards, its diameter will be more than slightly below the wellhead wide, covers not fall wellhead go.

And if with a square, the square because of its significantly longer than the diagonal length of each edge, such covers are rolled on, it is easy to fall into the wells diagonally wellhead, causing safety problems. If the wellhead made circular or significantly less than the covers, the covers will not fall into the square wells. Here involves a maximum use and conservation of a material problem. Wellhead wellhead use depends on the size, if you must install on top of a wellhead area is much larger than a square manhole cover, then the use of natural materials and practical value does not directly use the circular covers more efficiently, which saves material covers also to ensure the safety of the wellhead.

The cable in the country and well utilized, the general square, so you can better prevent rainwater into the liquid.

ingredient

Pig iron is the carbon content greater than 2% of the iron-carbon alloy, pig iron industry in general carbon content of 2.5% --4% and containing C, SI, Mn, S, P and other elements, with iron ore by blast furnace product. According to the different forms of pig iron in the presence of carbon, can be divided into steel-making pig iron, cast iron and ductile iron and so are several.

Precipitated spherical graphite cast iron. Spheroidal graphite split the role of the metal substrate is smaller than the flake graphite cast iron the strength of 70 to 90% of the matrix structure strength, tensile strength of up to 120kgf / mm2, and with good toughness. Ductile iron outer chemical composition is typically: 3.6 to 3.8% carbon content, silicon content of 2.0 to 3.0% manganese, phosphorus, sulfur, total does not exceed 1.5% and the amount of rare earth magnesium ball agent.

performance

Ductile iron castings has been in almost all major industrial sectors in the application of these sectors require high strength, ductility, toughness, wear resistance, resistance to severe thermal and mechanical shock, high temperature or low temperature resistance, corrosion resistance and dimensional stability. In order to meet the conditions of use of these changes, many of the existing grade nodular cast iron, provides mechanical properties and rational can kiss a very wide range.

Such as the International Organization for Standardization ISO1083 under the most ductile iron castings, mainly in the state of non-alloy production. Obviously, this range includes a tensile strength greater than 800 N / mm, elongation of 2% high strength grades. Ductile iron covers common material for QT500-7, Brinell hardness 170-230HB. At the other extreme is a high-grade plastic, elongation greater than 17%, while the corresponding lower strength (minimum 370 N / mm spoon. Strength and elongation of the root is not the only designer to select materials, and other important properties decisive further including yield strength, modulus of elasticity, wear resistance and fatigue strength, stiffness and impact properties. Moreover, corrosion and oxidation resistance and electromagnetic properties may be critical for designers. to meet these special use, we developed a set of austenitic ductile iron, usually called a proud Ni Resis death ductile iron. these austenitic ductile iron, primarily zinc, chromium and manganese alloyed, and the inclusion of international standards.