POSCO Holdings Inc.
PLATED STEEL SHEET HAVING EXCELLENT SURFACE QUALITY, STRENGTH AND DUCTILITY

Abstract:

Disclosed are: a plated steel sheet having a plating film on a surface of a hot-rolled steel sheet; and a method for manufacturing the same, wherein the hot-rolled steel sheet comprises, by weight, 0.15 to 0.25% of C, 0.5% or less of Si, 0.5 to 2.0% of Mn, 0.03% or less of P, 0.015% or less of S, 0.05% or less of Al, 0.01% or less of N, 0.05% or less of Ti (excluding 0%), 0.01% or less of B (excluding 0%), a balance of Fe, and inevitable, impurities, satisfies the following relationship 1, and comprises, by area, 10 to 30% of ferrite, 20 to 40% of pearlite, and 35 to 55% of bainite, as a microstructure: 0.235 [C]+0.0158 [Mn]+0.0625 [Si]+0.0423 [Mo]+0.317 [Ti]+1.36 [Nb].ltoreq.0.075 [Relationship 1] Where [C], [Mn], [Si], [Mo], [Ti], and [Nb] represent the content (by wt %) of the corresponding elements contained in the steel sheet, respectively.