Steel sheet with excellent phosphatability and manufacturing method therefor
AssigneePosco
InventorsByoungho Lee, Jina Kim, Youngkwang Hong
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Abstract
A steel sheet with excellent phosphatability, according to one embodiment of the present invention, comprises, by wt %, 0.02-0.06% of carbon (C), 0.01% or less of silicon (Si) (excluding 0%), 0.1-0.24% of manganese (Mn), 0.02% or less of aluminum (Al) (excluding 0%), 0.015-0.04% of phosphorus (P), and the balance of iron (Fe) and inevitable impurities, and has an oxide layer having a thickness of 10 nm or less inward from the surface of the steel sheet, and satisfies the following formula 1. ([Mn]+[Si]+[Al])/(3×[P])≤0.6 [Formula 1] (In formula 1, [Mn], [Si], [Al] and [P] mean the maximum amount of each element when elemental analysis is carried out in the thickness direction of the oxide layer.)
Claims11
A steel sheet with excellent phosphatability, comprising:
- by wt %, 0.02 to 0.06% of carbon (C), 0.01% or less of silicon (Si) (excluding 0%), 0.1 to 0.24% of manganese (Mn), 0.02% or less of aluminum (Al) (excluding 0%), 0.015 to 0.04% of phosphorus (P), and the balance of iron (Fe) and inevitable impurities, wherein the steel sheet has an oxide layer having a thickness of 10 nm or less inward from the surface of the steel sheet,
- satisfying the following formula 1, and
- contains cementite in an area fraction of 2% or more, and the balance of ferrite,
- ([Mn]+[Si]+[Al])/(3×[P])≤0.60 [Formula 1]
- wherein, in formula 1, [Mn], [Si], [Al] and [P] mean the maximum amount of each element when elemental analysis is carried out in the thickness direction of the oxide layer.
Dependencies are inferred from the claim text.