It is generally believed that the higher the temperature of molten iron, the longer the action time, and the higher the carbon absorption rate. But the reality is just the opposite. In the induction furnace, carbon is increased at low temperature and silicon is increased at high temperature. That is, at high temperature, instead of increasing carbon, it is reducing carbon.

This is because graphite carbon is mainly lost in the gas phase diffusion to the atmosphere outside the furnace; the oxidation of molten iron is related to the balance of C-Si-O, CO in molten iron is continuously oxidized to CO2, and CO2 will be reduced by C, and the reaction produces CO, CO2 gas floats up and overflows the surface of the molten iron, reducing the carbon content in the molten iron. The reaction rate is related to the equilibrium temperature, and the equilibrium temperature varies with the content of carbon and silicon. For ductile iron, the equilibrium temperature is about 1450°C±20°C, and for gray iron, it is about 1400°C±20°C. The oxidation of carbon in molten iron becomes violent above the equilibrium temperature. As a result of the reaction, the carbon in the molten iron is continuously oxidized and burnt, and the burnt loss of silicon is reduced. At this time, the carburizer added on the surface of the molten iron makes the carburization and carbon reduction of the molten iron reach a balance.