High-carbon steel sheet having good surface quality and manufacturing method therefor
Provided are a high-carbon steel sheet having good surface quality and a manufacturing method therefor. The present invention provides a high-carbon pickled steel sheet having good surface quality, the steel sheet containing, in weight %, 0.4% or more and less than 1.2% of carbon (C), 0.5% or less (excluding 0%) of silicon (Si), 0.05% or less of phosphorus (P), 0.03% or less of sulfur (S), 0.1 to 2.5% of at least one of manganese (Mn) and chromium (Cr), and the balance of iron (Fe) and inevitable impurities, wherein the 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 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 2 μm or less.
1 . A high-carbon pickled steel sheet having good surface quality, comprising, in weight %:
0.4% or more and less than 1.2% 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), 0.1 to 2.5% in total 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 high-carbon pickled steel sheet having good surface quality 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.
3 . A high-carbon cold-rolled steel sheet having good surface quality, comprising, in weight %:
0.4% or more and less than 1.2% of carbon (C), 0.5% or less and excluding 0% of silicon (Si), 0.02% or less of phosphorus (P), 0.01% or less of sulfur(S), 0.1 to 2.5% in total 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×[1−cold reduction ratio] μm to 10×[1−cold reduction ratio] 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.
4 . The high-carbon cold-rolled steel sheet having good surface quality of claim 3 , wherein the average thickness of the internal oxide layer and/or the decarburized layer formed in the surface layer portion of the steel sheet is in a range of 0.2 to 8 μm.
5 . The high-carbon cold-rolled steel sheet having good surface quality of claim 3 , 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.