Knowledge

Spheroidizing agent is an additive used to obtain ductile iron with spherical graphite. It is mainly composed of certain metals or alloys and is added to the molten iron to promote the crystallization of graphite into a spherical shape.

I. Definition and Purpose of Spheroidizing Agent

Spheroidizing agent is a certain metal or alloy added to molten iron to obtain ductile iron with spherical graphite. Its main purpose is to transform the graphite morphology in cast iron from flake to spherical, thereby enhancing the mechanical properties, toughness and plasticity of cast iron. The spherical graphite in ductile iron is formed after spheroidization treatment. This form of graphite makes the strength of cast iron much higher than that of gray cast iron, and its toughness is better than that of malleable cast iron, while still maintaining a series of advantages of gray cast iron.

II. Main Components of Spheroidizing Agents

The main components of spheroidizing agents include spheroidizing elements such as magnesium, rare earth, silicon, calcium, barium, and iron. Among them, magnesium is the most commonly used spheroidizing element due to its strong spheroidizing ability. Rare earth elements also play an important role in the spheroidizing process, as they can enhance the spheroidizing effect, reduce the tendency of white cast iron, and improve the fluidity and purity of cast iron. Silicon is mainly used to adjust the chemical composition of molten iron and promote the graphitization process.

III. Types of Spheroidizing Agents

Spheroidizing agents can be classified into various types based on their composition and application, such as ferrosilicon rare earth magnesium spheroidizing agent, calcium silicide spheroidizing agent, rare earth alloy spheroidizing agent, calcium silicoaluminate spheroidizing agent, aluminum titanium alloy spheroidizing agent, and nickel magnesium spheroidizing agent, etc.

Silicon-iron-rare earth-magnesium spheroidizing agent: This is a commonly used type of spheroidizing agent in China, mainly composed of silicon-iron, calcium, magnesium, rare earth, etc., which are melted and mixed. This spheroidizing agent can effectively deoxidize and desulfurize during the steel casting process, and also significantly improve the fluidity of molten iron.

Silicon-calcium alloy spheroidizing agent: Made mainly from silicon and calcium, it can spheroidize ferrite into spherical shapes during the steel smelting process, improving the quality of ferroalloys and reducing energy consumption and processing costs.

Rare earth alloy spheroidizing agent: This is a high-end spheroidizing agent, including lanthanum oxide, gadolinium oxide, cerium oxide, praseodymium oxide, etc. It can enhance the quality and stability of ferroalloys and is widely used in high-speed rail, aerospace, automotive manufacturing and other industries.

IV. Characteristics and Advantages of Spheroidizing Agents

Strong spheroidizing ability: Magnesium, rare earth and other elements in the spheroidizing agent have a strong spheroidizing ability, which can transform the graphite morphology in cast iron from flake to spherical.

Improved performance: Spheroidized cast iron has higher strength, toughness and plasticity, with significantly enhanced mechanical properties.

Improved fluidity: Some components in the spheroidizing agent can improve the fluidity of molten iron, reducing defects such as slag and bubbles during the casting process.

Reduced energy consumption and cost: The use of spheroidizing agents can increase casting efficiency and quality, while reducing energy consumption and processing costs.

V. Application Fields of Spheroidizing Agents

Spheroidizing agents are widely used in the steel industry, especially in the manufacturing of automobiles, railways, and ships. Adding a small amount of spheroidizing agent during the casting process can significantly improve the performance of cast iron. In addition, spheroidizing agents are also used in the manufacturing of aluminum alloys and electronic products, to reduce the surface tension of liquid metals, improve fluidity, enhance the surface quality of castings, and improve the microstructure and performance of alloys.

VI. Precautions for Using Spheroidizing Agents

Correct feeding sequence: When using spheroidizing agents, it is necessary to follow the correct feeding sequence to ensure their effectiveness and safety.

Raw material selection: Select high-quality raw materials such as rare earth, magnesium, silicon, and iron, and ensure the purity and stability of the raw materials.

Operational safety: Since elements such as magnesium used for spheroidization are flammable and explosive, strict adherence to safety regulations is required during operation to ensure the safety of personnel and equipment.

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