Nodular cast iron profiles are mainly composed of iron, carbon and silicon. In these alloys, the carbon content exceeds that which can be retained in austenite solid solution at eutectic temperature. In the structure, the graphite ball is fine and round, with high spheroidization rate, many balls, no intergranular carbide, high strength and high plasticity.
Because of its unique composition and characteristics, the nodular cast iron profile has a series of advantages, such as uniform and dense structure, good pressure and air tightness; strong wear reduction performance, bright and clean surface quality, high dimensional accuracy, small machining allowance, uniform hardness distribution, high tensile strength, no shrinkage porosity, air hole, slag inclusion, sand hole and other defects, superior mechanical properties, smong which the outstanding ones it is the combination of high strength and high toughness and excellent fatigue resistance.
Do you know how ductile iron sections are formed? It's very simple. First, the gray cast iron is obtained by spheroidizing, and the precipitated graphite is spherical. Spheroidizing the nodular graphite means that the size of metal particles becomes smaller, which will also improve the strength and hardness of the material.
The aim of normalizing this kind of nodular iron is to obtain pearlite matrix structure, refine grain and even structure, so as to improve the mechanical properties of castings. sometimes normalizing is also the preparation of surface quenching on the structure of nodular iron, and normalizing includes high temperature normalizing and low temperature normalizing.
The high temperature normalizing temperature of nodular cast iron profile is generally no more than 950-980 ℃, and the low temperature normalizing temperature is generally heated to 820-860 ℃. After normalizing, generally four people are needed to deal with it to eliminate the internal stress produced during normalizing. Because ductile iron profiles have higher strength, better toughness and plasticity than ordinary gray iron, they are often used to manufacture internal combustion engines, auto parts and agricultural machinery.