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Non-metallic inclusions in continuous casting billet
Non-metallic inclusions in the continuous casting billet are mainly organic and inorganic non-metallic materials. Organic materials mainly include organic polymeric materials, such as polyvinyl alcohol, polyethylene, polyamide, polystyrene and other polymers, while inorganic materials mainly include silicates, sulfates, carbonates and other inorganic compounds. These are the main processing components of molten steel, smelting and casting process, but also the stable form of non-metallic particles produced in the manufacturing process.
Organic non-metallic inclusions are generally present in the form of gel-like particles. Alumina, silica and other inorganic non-metallic inclusions are refractory materials, which are difficult to be removed and replaced during the production process of the continuous casting billet, so they are often affected by the process conditions and mechanical strength of the steel. They can also form refractory network structures, which need to be broken in the steel release process to obtain slag and float out the molten steel.
In addition, the non-metallic inclusions in the continuous casting billet also include various heteropoly acid salts, especially the alkali metal phosphate and acid alkali metal salts, which can also form a stable network structure, which is difficult to remove. Moreover, these heteropoly acid salts also react with each other and bond residues on the billet surface, causing red rust or orange spots. This kind of corrosion will affect the surface quality of the billet and the accuracy of the product.
In general, the non-metallic inclusions in the continuous casting billet have a large impact on the quality of the product, especially on its metal structure, mechanical properties, surface quality and dimensional accuracy. As early as the beginning of continuous casting process design, a variety of measures should be taken to prevent the production of non-metallic inclusions, including deoxidation and removing agents and slag floating agents.
The application of various deoxidation agents, removing agents and slag floating agents can reduce the content of non-metallic inclusions, and also improve the liquidity of molten steel and reduce the oxidation degree of molten steel. Furthermore, refining agents such as aluminium, calcium and chlorine-based materials can be added to improve the effects of deoxidation and slag floating and enhance the mechanical properties of the continuous casting billet.
In the operation, attention should be paid to the operation procedure, operation sequence and production operation state of the continuous casting machine. At the same time, preventive measures should be taken to reduce the non-metallic inclusions formed in the production process by controlling the addition time and dosage of each raw material. In addition, attention should also be paid to control the casting temperature and speed of the molten steel, in order to avoid the formation of large non-metallic inclusions due to temperature and speed differences. The correct addition of slag floating agent and proper control of the casting process should also be carried out to improve the surface quality of the billet.
In summary, reducing the content of non-metallic inclusions in the continuous casting billet requires a full understanding of the chemical components of the steel, scientific use of deoxidizing and refining agents, control of the production process, and control of the dosage of each raw material. All of these measure must be adopted to reduce non-metallic inclusions and improve the quality of the billet.
