Classification of recarburizers for casting

The classification of foundry recarburizers can be divided into several different types according to different classification basis and standards.

1. According to the casting purpose, it is divided into: ductile iron recarburizer, gray iron recarburizer, cast steel recarburizer, special recarburizer:

• The ductile iron recarburizer is generally made of graphitized high-carbon and low-sulfur products. The basic index requirements are: C>98.5 S<0.05; its main materials are graphitized petroleum coke, graphitized electrodes, etc. It is also the highest absorption rate and the fastest absorption time among the recarburizers.

• The main technical index difference between grey iron recarburizer and ductile iron recarburizer is the control of sulfur. The general index requirement is S<0.5, and the C content can be selected as 98.5 95 93 90 and so on according to the cost control requirements. The absorption rate of such recarburizers is generally around 85%. Its main materials are non-graphitized petroleum coke, calcined coal, etc.

• There are many types of recarburizers for cast steel (steel making), generally large steel mills will choose a variety of recarburizers according to different steel types, but the general material is calcined coal, or graphite balls, and natural graphite fragments are also useful. . The content varies from 75-99.

• Special recarburizers are mainly used in the manufacture of brake pads and cored wires, and petroleum coke with a particle size of 0-0.5 or 0.5-1MM is mostly used.

2. According to the material, it can be generally divided into: metallurgical coke recarburizer, calcined coal recarburizer, petroleum coke recarburizer, graphitization recarburizer, natural graphite recarburizer, composite material recarburizer:

• The so-called metallurgical coke recarburizer is the large coke usually used in cupola furnaces. Its function is not only smelting, but also carbonizing the metal charge, and its indicators will not be repeated.

• The calcined coal carburizer is mainly produced in Shizuishan, Ningxia and Wuhai, Inner Mongolia. The composition is generally C: 90-93%, S0.3-0.5. It is mainly used in steelmaking enterprises, and some casting enterprises use it for gray cast iron. The disadvantage is that the carbon content is low, the melting is slow, electricity is wasted, and the residual amount is large.

• Petroleum coke recarburizers are mainly produced in Liaoning, Tianjin and Shandong. Liaoning mainly produces projectile coke, which is not very good for casting. Petroleum coke in Shandong and Tianjin can be used to cast gray cast iron. The composition is generally C: 96-99%; S0.3-0.7%. Mainly used in steelmaking, gray cast iron, brake pads, cored wire and so on.

• Graphitized recarburizers are mainly produced in Shandong, Henan, etc. There are few manufacturers, and the main materials are graphitized petroleum coke and graphitized electrodes. The general composition is carbon content > 98-99.5%; sulfur < 0.05-0.03. Mainly used for ductile iron. It is characterized by fast absorption, high carbon and low sulfur.

• Natural graphite recarburizer, mainly natural graphite, ranging from 65 to 99 carbon, mainly used in steelmaking plants, not applicable in foundries.

2.6 Recarburizers for composite materials. Recently, there are some artificially-made stick-shaped particles or regular spherical particles in the market, which are made of graphite powder, coke powder, petroleum coke, etc. Generally between 93-97, sulfur is unstable, generally floating between 0.09-0.7. The characteristic is that the price is cheap, and the disadvantage is that it cannot be used to stabilize the addition amount and control the sulfur content.