There are three main aspects of the effect of carburizer on melting:

1. Liquid iron carburization technology, in the melting process, especially in the electric furnace melting, can increase the graphite nucleus. The addition of silicon carbide in cupola smelting can also increase the long-term graphite nucleus of hot metal and reduce the oxidation of hot metal.
2. Carburization is a better measure to prevent or reduce the tendency to shrink. During the solidification process of hot metal, due to the effect of graphitization expansion, good graphitization can reduce the shrinkage tendency of hot metal.
3. Under the condition of higher carbon content, in order to obtain high-strength gray cast iron castings, the process of using all scrap steel and scale inhibitor in the smelting process makes the iron liquid more pure and the casting performance is higher.
It is generally believed that the higher the temperature of hot metal, the longer the action time, the higher the carbon absorption rate. But in fact just the opposite, in the induction furnace is low temperature carburization, high temperature silicon, that is, at high temperature, not only do not carburize, but reduce carbon, this is because: ① graphite carbon is mainly lost in the gas phase diffusion to the atmosphere outside the furnace; ② The oxidation in hot metal is related to the balance of C-Si-O, the CO in hot metal is continuously oxidized to CO2, and CO2 will be reduced by C, the CO produced by the reaction,CO2 gas floats up and overflows the surface of hot metal, so that the carbon content in hot metal decreases. The reaction rate is related to the equilibrium temperature, which varies with the content of carbon and silicon. For ductile iron, the equilibrium temperature is about 1450 ° C ±20 ° C, and gray iron is about 1400 ° C ±20 ° C. The hot metal becomes more intense at equilibrium temperature through the oxidation of the above carbon. As a result of the reaction, the carbon in the hot metal is continuously oxidized and burned, reducing the combustion loss of silicon. Silicon burn loss is reduced. At this time, adding a carburizer to the surface of the hot metal makes the carburizing and decarbonizing in the hot metal reach an average level.
According to the above analysis, the following induction furnaces with proper use of carburizing agents are:
1. If the electric furnace of more than 5T is used, because the raw material is single and stable, we recommend the dispersed addition method. According to the requirements of carbon content, according to the ratio of ingredients, the carburizer and metal charge are added to the lower part of the electric furnace together with each batch of materials, a layer of metal charge and a layer of carburizer, the carbon absorption rate can reach 90%-95%, the carburizer does not slag when melting, otherwise it is easy to wrap in the waste slag, affecting the carbon absorption;
2. If the medium frequency induction furnace of about 3T is used, we recommend the centralized addition method due to the single stability of the raw material. When the remaining small amount of hot metal is melted in the furnace, the carburizer to be added is added to the surface of the hot metal at one time, and the metal charge is added immediately, and the carburizer is pressed into the hot metal, so that the carburizer is fully in contact with the hot metal, and the absorption rate is more than 90%.
3. The use of small medium frequency electric furnace, raw materials with pig iron and other high carbon substances, we recommend carburizer fine-tuning. After the steel/hot metal is melted, the carbon content can be adjusted, and it can be added to the surface of the steel/hot metal. The product is dissolved and absorbed by the eddy current stirring of the steel (iron) water in the electric furnace, and the carbon absorption rate is about 93%.