Patent ID: 11952652
Assignee: POSCO CO., LTD
Field: Surface technology, coating (Chemistry)
Classification: CPC C  Y | IPC B  C

Claim 0:
1. A method of manufacturing a hot-press part, the method comprising:
coating a metal on a steel sheet to form a metal coated steel sheet, wherein the metal is one or more selected from the group consisting of Ni, Co, Cu, Sn and Sb, and wherein the metal has a reduced amount of Gibbs free energy for one mole of oxygen during an oxidation reaction, the reduced amount of Gibbs free energy being smaller than that of Cr;
annealing the metal coated steel sheet to form an annealed steel sheet at a temperature range of 700° C. to 900° C. in a gas atmosphere of 3 to 5 vol % of hydrogen (H2) where a dew point temperature of the gas atmosphere is −10° C. or less;
forming a zinc plating layer on the annealed steel sheet to form a zinc-plated steel sheet by dipping the annealed steel sheet in a molten zinc plating bath;
heating the zinc-plated steel sheet within a temperature range of about 750° C. to about 950° C. at a heating rate ranging from about 2° C./sec to about 10° C./sec in an oxidizing atmosphere to form a heated zinc-plated steel sheet; and
press forming the heated zinc-plated steel sheet to form the hot-press part,
wherein the hot-press part comprises:
a base steel sheet;
a zinc plating layer including a Fe—Zn phase having a metal, in which a reduced amount of Gibbs free energy for one mole of oxygen during an oxidation reaction is smaller than that of Cr, dissolved in an amount of about 0.008 wt % or more formed on the base steel sheet; and
an oxide layer having an average thickness range of about 0.01 μm to about 5 μm formed on the zinc plating layer, and
wherein the oxide layer comprises a continuous coating layer having an average thickness range of about 10 nm to about 300 nm, the continuous coating layer comprising one or more oxides selected from the group consisting of SiO2 and Al2O3, and an oxide including ZnO and MnO is formed on the continuous coating layer.