METHOD FOR MANUFACTURING HOT-DIP ZINC-COATED STEEL SHEET SHOWING BLACK COLOR, AND METHOD FOR MANUFACTURING FORMED BODY OF THE HOT-DIP ZINC-COATED STEEL SHEET SHOWING BLACK COLOR

摘要

PROBLEM TO BE SOLVED: To provide a hot-dip zinc-coated steel sheet showing black color having excellent retentivity of black appearance and excellent workability.;SOLUTION: In the method for manufacturing the hot-dip zinc-coated steel sheet showing black color, a Zn coated steel sheet having a Zn coating layer containing molten Al, Mg and containing a three-component eutectic structure of Al/Zn/Zn₂Mg as a base sheet is brought into contact with steam of the temperature of ≥105°C, and the ratio of an amount by mole after being brought into contact with the steam to an amount by mole before being brought into contact with the steam is set to be within a predetermined range for oxides and hydroxides of Zn, Al and Mg of the surface layer of the coating layer. Further, in the method for manufacturing the hot-dip zinc-coated steel sheet showing black color, the Zn coating layer containing molten Al and Mg contains the three-component eutectic structure of Al/Zn/Zn2Mg.;COPYRIGHT: (C)2012,JPO&INPIT