Abstract: A method for evaluating center segregation of a continuous cast slab is provided. The method of the present invention includes (A) creating a center segregation image of a slab using an etching solution comprising a picric acid (C6H3N3O7), a cupric chloride (CuCl2), sodium laurylbenzenesulfonate (C18H29SO3Na) and the remainder of distilled water; and (B) evaluating the center segregation of a slab by scanning the image and applying the following Formula. The method creates an image of center segregation even for low-carbon steel having carbon (C) in an amount of 0.04 wt % or less as well as ultra low-sulfur steel having sulfur (S) in an amount of 50 ppm or less.

Abstract: Disclosed is a method of predicting surface quality of a thin slab hot rolled coil. The method includes calculating the Cu equivalent (Cu eq.) of molten steel, applying the calculated Cu equivalent of the molten steel into an equation: 120×(Cu equivalent)2?6×(Cu equivalent) to calculate a surface crack index, and predicting the generation of surface defect of the thin slab hot rolled coil by the surface crack index. A method of producing the thin slab hot rolled coil using the same is also provided. The surface crack defect of the thin slab hot rolled coil can be predicted by calculating the Cu equivalent of the molten steel, and thus a thin slab which meets the quality standard demanded by a consumer can be provided, and this results in increased productivity and product reliability.

Abstract: A method for evaluating center segregation of a continuous cast slab is provided. The method of the present invention includes (A) creating a center segregation image of a slab using an etching solution comprising a picric acid (C6H3N3O7), a cupric chloride (CuCl2), sodium laurylbenzenesulfonate (C18H29SO3Na) and the remainder of distilled water; and (B) evaluating the center segregation of a slab by scanning the image and applying the following Formula. The method creates an image of center segregation even for low-carbon steel having carbon (C) in an amount of 0.04 wt % or less as well as ultra low-sulfur steel having sulfur (S) in an amount of 50 ppm or less.

Abstract: Disclosed is a method of predicting surface quality of a thin slab hot rolled coil. The method includes calculating the Cu equivalent (Cu eq.) of molten steel, applying the calculated Cu equivalent of the molten steel into an equation: 120×(Cu equivalent)2?6×(Cu equivalent) to calculate a surface crack index, and predicting the generation of surface defect of the thin slab hot rolled coil by the surface crack index. A method of producing the thin slab hot rolled coil using the same is also provided. The surface crack defect of the thin slab hot rolled coil can be predicted by calculating the Cu equivalent of the molten steel, and thus a thin slab which meets the quality standard demanded by a consumer can be provided, and this results in increased productivity and product reliability.

Abstract: The present invention relates to an apparatus for centering a submerged entry nozzle. The present invention includes: a plurality of laser beam generators 20 that is disposed above a mold 3 for continuous casting to radiate a laser beam toward the center of the mold; a tundish moving unit 15 that moves a tundish 1 above the mold 3; and a control unit that is linked with the laser beam generators 20 and controls the tundish moving unit 15 to center the installation position of the submerged entry nozzle 5 provided at the lower portion of the tundish, in response to signals transmitted from the laser beam generators 20. According to the present invention, in addition to accurately and quickly centering the submerged entry nozzle 5, it is possible to maintain the submerged entry nozzle that has been centered, such that it is possible to minimize a channeling phenomenon of molten steel. Accordingly, it can be expected to improve the quality of a slab.

Abstract: The present invention relates to an apparatus for centering a submerged entry nozzle. The present invention includes: a plurality of laser beam generators 20 that is disposed above a mold 3 for continuous casting to radiate a laser beam toward the center of the mold; a tundish moving unit 15 that moves a tundish 1 above the mold 3; and a control unit that is linked with the laser beam generators 20 and controls the tundish moving unit 15 to center the installation position of the submerged entry nozzle 5 provided at the lower portion of the tundish, in response to signals transmitted from the laser beam generators 20. According to the present invention, in addition to accurately and quickly centering the submerged entry nozzle 5, it is possible to maintain the submerged entry nozzle that has been centered, such that it is possible to minimize a channeling phenomenon of molten steel. Accordingly, it can be expected to improve the quality of a slab.