Square Ductile Iron Manhole Cover

 The spheroidal manhole cover is a kind of spheroidal graphite cast iron. The spheroidal graphite cast spheroidal graphite is spheroidized and inoculated to effectively improve the mechanical properties of the cast iron, especially the plasticity and toughness, thereby obtaining higher strength than the Carbon Steel. Ductile iron is a kind of high-strength cast iron material developed in the 1950s. Its comprehensive performance is close to that of steel. It is based on its excellent performance and has been successfully used for casting some complex forces, strength, toughness and wear resistance. Parts with higher requirements. Ductile iron has rapidly developed into a widely used cast iron material after gray cast iron. The so-called "iron-based steel" mainly refers to ductile iron.

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 Cast iron manhole covers are generally divided into round and square. In the urban area, circular is generally used, because the round manhole cover is not easy to tilt, which can better protect the safety of pedestrians and vehicles. The use of a circle is mainly due to the fact that the circular manhole cover has the same length through each of its centers, so that if the manhole cover is rolled up by the passing vehicle, the diameter will be slightly smaller than the wellhead below. Wide, the manhole cover will not fall into the wellhead. If square is used, because the diagonal of the square is obviously longer than the length of each side, when the manhole cover is rolled up, it is easy to fall into the well along the diagonal direction of the wellhead. , causing security risks. If the wellhead is rounded or significantly smaller than the manhole cover, the square manhole cover will not fall into the well. This involves the problem of utilization and savings of a material. The use of the wellhead depends on the size of the wellhead. If a square manhole cover with a much larger area than the wellhead is to be installed on it, then the material utilization and practical value are naturally not more effective than using a circular manhole cover directly, which not only saves the material of the manhole cover, but also The safety of the wellhead is ensured and used in the countryside and cable wells, generally square, which can better prevent the entry of liquids such as rainwater.

 Ductile iron castings have been used in almost all major industrial sectors, requiring high strength, ductility, toughness, wear resistance, resistance to severe thermal and mechanical shocks, high or low temperatures, corrosion resistance and dimensional stability. In order to meet these variations in the conditions of use, there are many grades of ductile iron available, providing a wide range of mechanical properties and kinematic properties. Most ductile iron castings, as defined by ISO 1083, are mainly produced in non-alloyed state.Obviously, this range includes high-strength grades with tensile strength greater than 800 Newtons/mm and elongation of 2%. QT500-7, a general-purpose material for ductile iron manhole covers, has a Brinell hardness of 170-230HB. The other extreme is a high-resistance grade with an elongation of more than 17% and a correspondingly low strength (minimum of 370 N/mm scoop. Strength and elongation are not the only roots of the designer's choice of material, while other decisive important properties Also included are yield strength, modulus of elasticity, wear and fatigue strength, hardness and impact properties. In addition, corrosion resistance and oxidation resistance and electromagnetic properties may be critical to the designer. To meet these special uses, a group has been developed. Austenitic ductile iron, usually called Ni-Resis, is a ductile iron. These austenitic ductile irons are mainly alloyed with zinc, chromium and manganese and are listed as international standards.