carbon for cast iron

The five major elements in cast iron are carbon, silicon, manganese, sulfur, and phosphorus. Carbon and silicon are the two most important chemical elements in ordinary gray cast iron. They have a decisive influence on the structure and performance of cast iron. In production, the structure and performance of ordinary gray cast iron are often controlled and adjusted by controlling and adjusting the content of carbon and silicon. 

Carbon itself is the element that constitutes graphite. Increasing the carbon content can increase the homogeneous crystal nuclei of graphite, and also increase the undissolved graphite inclusions in the molten iron, and increase the heterogeneous crystal nuclei of graphite, which can increase the actual crystallization temperature of molten iron.Therefore, carbon is an element that promotes graphite in cast iron.The general types of the carbon can be divided into calcined petroleum coke, graphitized petroleum coke and graphite carbon according to the different materials, the calcined petroleum coke always with the content of carbon 98% at least and sulfur content 0.5% at most, the graphitized often with the carbon 98.5% at least and the sulfur 0.05% at most, as for the graphite carbon there is existed the columnar graphite carbon in the shape of columnar, which is the carbon compound.Though the carbon is advantage in the cast iron, however, if the carbon content is too high, the degree of graphitization of the cast iron will increase, the graphite will be coarse, the spheroid in the matrix will decrease, the ferrite will increase, and the mechanical properties of the casting will decrease.In order to improve the strength of cast iron, make the graphite in structure refine, the graphite amount reduced and increase the pearlitem it is necessary to appropriately reduce the carbon content in the cast iron.

Generally speaking, for the gray cast iron can adopt the calcined petroleum coke and graphite carbon and graphitized petroleum coke, actually the calcined petroleum coke and graphite carbon is enough compared, because of the cost of graphitized petroleum coke is much higher; if for the ductile cast iron you can just choose graphitized petroleum coke because of its low sulfur and low nitrogen, the sulfur content is generally 0.05% at most, and nitrogen is 300PPM,because of low sulfur and low nitrogen, it can more effectively prevent blowholes in castings.

Anyang Huauto has in the materials for casting and steel-making for more than ten years, if you do not know how to choose proper carbon can contact us.