The principle of carburizer mainly includes its mechanism of action in the steel smelting process and the characteristics of the carburizer itself.
Mechanism of action of carburizer in steel smelting
During the smelting process of steel products, due to factors such as long smelting time, insulation time, and overheating time, the carbon element in the molten iron will be lost in smelting, resulting in a decrease in the carbon content in the molten iron, which cannot reach the expected theoretical value of refining. In order to make up for this part of the burned carbon content, it is necessary to add a carbon-containing substance, which is the carburizer. The use of carburizer is crucial for steel smelting. It can not only help steel reach the expected carbon content, but also improve the nucleation ability of molten iron and refine the grains, thereby improving the tensile strength, hardness, wear resistance and fatigue limit of the casting. Mechanical properties. In addition, carburizer can also improve the distribution of carbon and alloy elements in the casting metal, make the structure of the casting dense and uniform, and eliminate the segregation phenomenon generated during the casting process.
Characteristics of carburizer itself
There are many types of carburizers, which can be divided into many types according to different raw materials and production processes. Common types of recarburizers include:
Artificial graphite recarburizer: uses powdered high-quality calcined petroleum coke as the main raw material, adds asphalt as a binder, and graphitizes after high-temperature treatment.
Petroleum coke recarburizer: It is produced by coking the byproduct of refined crude oil and needs to be calcined to remove impurities.
Natural graphite recarburizer: It is divided into two categories: flake graphite and microcrystalline graphite, and medium carbon graphite is commonly used.
Coke and anthracite recarburizer: It is used in the steelmaking process of electric arc furnaces, but due to the high ash and volatile content, it is rarely used in induction furnaces for smelting cast iron.
Composite material recarburizer: It uses waste materials such as graphite powder, coke powder, and petroleum coke, and adds a binder to press and form.
Other types: Such as graphitized petroleum coke recarburizer, calcined coal recarburizer, metallurgical coke recarburizer, etc.
Effect and mechanism of carburizer in specific applications
When smelting cast iron in an induction furnace, there is no carbon source in the furnace and the amount of scrap steel in the charge is high, so carburizer is generally indispensable. The type and characteristics of the carburizer not only affect the carburization efficiency, but also have an important impact on the metallurgical quality of the casting. For example, the diffusion rate of graphite carburizer in molten iron is significantly faster than that of coke and coal particles, and it can increase the carbon content of molten iron more quickly.