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US 12,674,245 B2Granted
High-strength steel sheet having excellent surface quality and manufacturing method therefor
AssigneePosco
InventorsKang-Min Lee, Chung-Hwan Lee, Ki-Cheol Kang, Nam-A Kim, Yoon-Mo Jang
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Abstract
The present invention relates to a high-strength steel sheet having excellent surface quality due to improved coatability thereof and a method for manufacturing same.
Claims14
A high-strength steel sheet having excellent surface quality, comprising:
- a base steel sheet;
- and
- a ferrite layer formed on a surface layer portion of the base steel sheet,
- wherein the ferrite layer has an internal oxide layer on an upper portion thereof, the internal oxide layer having an Fe—Ni alloy layer formed thereon,
- the internal oxide layer is formed to a maximum depth of 3 μm in a thickness direction along a grain boundary of a matrix structure of the base steel sheet from a surface of the ferrite layer, and
- the Fe—Ni alloy layer is formed in the internal oxide layer to a maximum depth of 2 μm in the thickness direction along the grain boundary of the matrix structure of the base steel plate from the surface of the ferrite layer.
3 more elements
A manufacturing method for a high-strength steel sheet having excellent surface quality, the method comprising:
- preparing a base steel sheet;
- forming a Ni+Fe/rGO composite coating layer on at least one surface of the base steel sheet;
- and
- performing an annealing heat treatment on the base steel sheet having the composite coating layer formed thereon,
- wherein the annealing heat treatment is performed at a temperature range of at most 850° C. and a dew point temperature of −10 to +5° C.
2 more elements
Dependencies are inferred from the claim text.