Ductile iron castings are mainly alloys of iron, carbon and silicon in which the carbon content exceeds the amount retained in the austenite solid solution at the eutectic temperature. The graphite ball in the structure is fine and round, the spheroidization rate is high, the number of balls is large, there is no intercrystalline carbide, and the mechanical properties have both high strength and high plasticity.
It is precisely because of the unique composition and characteristics that the spheroidal graphite cast iron has uniform and compact structure, good pressure and air tightness; strong anti-wear performance, smooth surface quality, high dimensional accuracy, small processing allowance, uniform hardness distribution and resistance. It has a series of advantages such as high tensile strength, no shrinkage, porosity, slag inclusion, blisters and other mechanical properties. Among them, its combination of high strength and high toughness and excellent fatigue resistance.
Do you know how to form ductile iron profiles? Very simple, firstly, the gray cast iron hot water is obtained by spheroidizing, and the precipitated graphite is spherical; spheroidizing the spheroidal ink means that the size of the metal particles becomes smaller, which also increases the strength and hardness of the material.
This ball iron is then subjected to normalizing treatment in order to obtain a pearlite matrix structure, and to refine the grains and uniformly structure to improve the mechanical properties of the casting. Sometimes normalizing is also the preparation of the surface quenching of the ductile iron, the normalizing of the high temperature normalizing and the low temperature normalizing.
The high-temperature normalizing temperature of ductile iron profiles generally does not exceed 950-980 °C, and the low-temperature normalizing is generally heated to a common folding temperature range of 820-860 °C. After normalizing, four people are usually required to eliminate the internal stress generated during normalizing. Because ductile iron profiles have higher strength, better toughness and plasticity than ordinary gray cast iron, they are often used in the manufacture of internal combustion engines, auto parts and agricultural machinery.