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.