Posco

Posco Co., Ltd

Joong-Chul Park

Jong-Sang Kim

Jin-Keun Oh

Il-Ryoung Sohn

Yeol-Rae Cho

Han-Gu Cho

Bong-Hoon Chung

Jong-Seog Lee

Myung-Soo Kim

Yon-Kyun Song

Young-Ha Kim

Jae-Dong Cho

Hyun-Ju Jeong

Yun-Ha Yoo

A galvanized steel sheet according to one aspect of the present invention comprises: a base steel sheet; and a Zn—Al—Mg-based plating layer provided on at least one surface of the base steel sheet, wherein the Zn—Al—Mg-based plating layer may include a surface modified region enriched with cerium (Ce) on a surface layer side of the Zn—Al—Mg-based plating layer.

Surface modified galvanized steel sheet

Provided is a method of manufacturing a zinc-plated steel sheet. The method includes: coating a metal on the steel sheet on a steel sheet; annealing the metal coated steel sheet; and zinc plating the annealed steel sheet by dipping in a molten zinc plating bath. Further provided is a method of manufacturing a hot-press part including: coating a metal on the steel sheet on a steel sheet; annealing the metal coated steel sheet; zinc plating the annealed steel sheet by dipping in a molten zinc plating bath; heating the zinc-plated steel sheet; and press forming the heated steel sheet.

Zinc-plated steel sheet for hot pressing having outstanding surface characteristics, hot-pressed moulded parts obtained using the same, and a production method for the same

Provided is a method of manufacturing a hot-dip galvanized steel sheet. According to an aspect of the present invention, the method may include preparing a base steel sheet, forming a iron (Fe)-plated layer on the prepared base steel sheet, oxidation heating the steel sheet having the Fe-plated layer formed thereon at a temperature ranging from 600&#xb0; C. to 800&#xb0; C., maintaining the heated steel sheet at a temperature ranging from 750&#xb0; C. to 900&#xb0; C. for 5 seconds or more in a reducing atmosphere with a dew point of between &#x2212;30&#xb0; C. to 5&#xb0; C. including 20 ppm or less of oxygen, 1 vol % to 20 vol % of H, and Nas well as unavoidable gases as a remainder, cooling the maintained steel sheet, and plating the cooled steel sheet by dipping in a hot-dip galvanizing bath.

High-strength hot-dip galvanized steel sheet having excellent plating surface quality and adhesion, and method of manufacturing the same

Provided is a zinc-plated steel sheet for hot pressing having outstanding surface characteristics, comprising: a steel foundation plate comprising a metal surface diffusion layer of which the Gibbs free energy reduction per mole of oxygen during oxidation is less than that of Cr, an aluminum-rich layer containing at least 30 wt. % of aluminum formed on the surface diffusion layer, and a zinc plating layer formed on the aluminum-rich layer. In this way, a metal having a low affinity for oxygen is coated to an effective thickness prior to annealing and thus the creation of annealing oxides at the surface of the steel sheet is suppressed and a uniform zinc plating layer is formed, and alloying of the zinc plating layer is promoted during press-processing heat treatment. Cracking in the steel foundation plate during hot press molding is prevented.

Provided is a zinc-plated steel sheet for hot pressing having outstanding surface characteristics, comprising: a steel foundation plate comprising a metal surface diffusion layer of which the Gibbs free energy reduction per mole of oxygen during oxidation is less than that of Cr; an aluminum-rich layer containing at least 30 wt. % of aluminum formed on the surface diffusion layer, and a zinc plating layer formed on the aluminum-rich layer. In this way, a metal having a low affinity for oxygen is coated to an effective thickness prior to annealing and thus the creation of annealing oxides at the surface of the steel sheet is suppressed and a uniform zinc plating layer is formed, and alloying of the zinc plating layer is promoted during press-processing heat treatment. Cracking in the steel foundation plate during hot press molding is prevented.

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Gwangyang, South Korea

Joong-Chul Park