What are the functions and measurement methods for protecting the thickness of the liquid slag layer in a protective slag crystallizer?
Release time:
2020-07-29
Protective Slag It is an important auxiliary material in continuous casting production. With the development of steelmaking and continuous casting technology in China, Protective Slag technology is also constantly improving.
Protective Slag A liquid slag layer thickness that meets actual needs must be ensured to achieve good results. If the liquid slag layer is too thick or too thin, longitudinal cracks will appear on the surface of the slab. For example, if the casting speed of the billet is 1.2 to 1.5 m/min, and the thickness of the liquid slag layer is less than 5 mm, the longitudinal cracks of the billet will increase significantly (50 mm/m to 200 mm/m), and when the thickness of the liquid slag layer is 6 to 15 mm, the longitudinal cracks almost disappear; when the liquid slag layer is greater than 20 mm, the longitudinal cracks increase again.
When the liquid slag layer thickness is less than a certain value, the slag ring formed around the crystallizer will block the channel between the liquid slag flowing into the shell and the copper wall, preventing the liquid slag from smoothly flowing into the shell surface to form a uniform slag film, thus causing longitudinal cracks on the corresponding slab surface. So, what is the required thickness of the liquid molten slag for the liquid molten slag to flow down along the meniscus without being blocked? According to theoretical calculations, when the pulling speed is less than 1 meter/minute, the liquid slag layer thickness is 5 ~ 7 mm; when the pulling speed is greater than 1 meter/minute, the liquid slag layer thickness is 7 ~ 15 mm, which is consistent with the critical liquid slag layer thickness measured in production practice.
Method for measuring the liquid slag layer thickness in production: A steel wire and a copper wire (or aluminum wire) are tied together and inserted into the slag layer of the crystallizer. Because the temperature of the liquid slag is higher than the melting point of copper, the copper wire melts, and the melting length of the copper wire is measured as the thickness of the liquid slag layer. Because the molten steel temperature at various points on the cross-section of the slab mold is different (e.g., submerged nozzle area and mold edge), the thickness of the liquid slag layer is also different, so the thickness of the liquid slag layer at different positions can be measured.
More about Protective Slag For more questions, please consult Luoyang Turner High Temperature Instrument Co., Ltd., a professional manufacturer of high-temperature laboratory equipment and reagents.
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