Steel sheet with excellent surface quality, and manufacturing method therefor
A steel sheet with excellent surface quality, and a manufacturing method therefor are provided. The present invention provides a pickled steel sheet with excellent surface quality, comprising, by wt %, carbon (C) in an amount greater than or equal to 0.05% and less than 0.4%, 0.5% or less of silicon (Si) (excluding 0%), 0.05% or less of phosphorus (P), 0.03% or less of sulfur (S), 0.01% or less of boron (B), 0.1-2.5% of manganese (Mn) and/or chromium (Cr), and the balance of iron (Fe) and inevitable impurities, wherein the average thickness of an internal oxide layer and/or a tantalum layer, which are formed on the surface layer of the steel sheet, is 1-10 μm, and the standard deviation of the thickness of the internal oxide layer and/or the tantalum layer in the length direction of the steel sheet is 2 μm or less.
1 . A pickled steel sheet, comprising, by wt %:
0.05% or more and less than 0.4% of carbon (C), 0.5% or less and excluding 0% of silicon (Si), 0.05% or less of phosphorus (P), 0.03% or less of sulfur(S), 0.01% or less of boron (B), 0.1 to 2.5% of at least one of manganese (Mn) and chromium (Cr), and a balance of iron (Fe) and inevitable impurities,
wherein an average thickness of an internal oxide layer and/or a decarburized layer, formed in a surface layer portion of the steel sheet, is 1 to 10 μm, and
a standard deviation of the thickness of the internal oxide layer and/or the decarburized layer in a length direction of the steel sheet is 2 μm or less.
2 . The pickled steel sheet of claim 1 , wherein the following Relational Expression 1 is satisfied,
C(%)+Si(%)/6+Mn(%)/20+Cr(%)/20+2×P(%)+4×S(%)<0.5. [Relational Expression 1]
3 . The pickled steel sheet of claim 1 , wherein the standard deviation of the thickness of the internal oxide layer and/or the decarburized layer in the length direction of the steel sheet is 1.6 μm or less.
4 . The pickled steel sheet of claim 1 , wherein the steel sheet is obtained by immersing a hot-rolled coil in a pickling tank and passing the coil therethrough with a passing speed that is controlled along the coil length such that, when the coil is divided into first through fifth regions in the length direction, the passing speed in the second, third, and fourth regions is slower than the passing speed in the first and fifth regions.