Functions of continuous casting slag protection
Release time:
2023-01-06
During the continuous casting process, Continuous casting flux After being added to the mold, it is heated and sintered on the steel surface to form a liquid slag layer. When the mold powder near the liquid slag layer does not reach the melting temperature, it has been sintered into a transition layer. Above the transition layer is the original slag layer, which is the three-layer structure of the tundish powder that we usually call—liquid slag layer, sintered layer, and original slag layer. The liquid slag and liquid steel together form a meniscus near the crystallizer wall. Under the action of crystallizer vibration, gravity, and capillary adsorption, the liquid molten slag flows into the gap between the crystallizer wall and the billet shell through the meniscus, forming a slag film. The consumption of the liquid slag pool and liquid slag on the steel surface between the crystallizer wall and the billet shell forms a dynamic equilibrium. The functions of continuous casting flux are introduced below:
1. Heat insulation to reduce heat loss of molten steel
The continuous casting flux used for continuous casting must have good thermal insulation properties, which can inhibit the formation of bridges and crusts in the crystallizer during continuous casting, increase the meniscus temperature, make the shell grow stably at the meniscus, and make the radius of curvature of the meniscus large. With the increase of the radius of curvature of the meniscus, the bubbles and oxide inclusions floating from the molten steel at the bottom of the crystallizer are not easily captured by the meniscus, and are easier to float to the liquid slag layer, making the molten steel cleaner.
2. Isolate air to prevent secondary oxidation
Under the action of high temperature of molten steel, the continuous casting flux will quickly form a liquid slag layer, thus preventing air from diffusing to the steel surface. The three-layer structure of the mold powder is used to isolate oxygen and nitrogen, so that the molten steel is not subjected to secondary oxidation and nitrogen absorption. It not only prevents the secondary oxidation of molten steel and the oxidation of alloy elements in molten steel, but also prevents molten steel from absorbing nitrogen from the air, which is conducive to improving the cleanliness of molten steel.
3. Lubricate the slab to reduce slab adhesion
In order to reduce the occurrence of cracks and steel leakage accidents and improve the service life of the mold, good lubrication must be obtained between the mold copper plate and the billet to reduce mutual friction. At the meniscus around the mold, due to the vibration of the mold and the capillary action of the gap between the shell and the copper plate, the liquid molten slag formed by the melting of the continuous casting flux is sucked into the gap between the copper plate and the shell, forming a molten slag film for lubrication.
4. Improve crystallizer heat transfer
Due to the shrinkage of the shell in the mold, an air gap will be generated, which will increase the thermal resistance. Adding continuous casting flux powder makes the air gap filled with a uniform slag film, which can reduce the thermal resistance of the air gap, significantly improve the heat transfer of the mold, and make the shell grow uniformly. According to actual measurements, the thermal conductivity of the air gap is about 0.09W/(m2·K), the thermal conductivity of the slag film is 1.2W/(m2·K), and the thermal conductivity of pure copper is 389W/(m2·K), that is, the slag film is about 1/325 of pure copper, which is 13 times that of the air gap.
Related Blog
Scan
Luoyang Turner High Temperature Instrument Co., Ltd.
+86-400-880-7095
Sales (same as WeChat):18695992058
Contact:+86-379-69755886
Address: South Section of Shuangxiang Road, Luoxin Industrial Cluster, Luoyang City, Henan Province
Email:tnkinstrument@163.com
Copyright © Luoyang Tainake High-Temperature Instrument Equipment Co., Ltd. IPV6