Posco

Noroo Coil Coatings Co., Ltd.

Posco Coated & Color Steel Co., Ltd.

Dae-Chul Bae

Il-Ryoung Sohn

Heung-Yun Kim

Soo-Hyoun Cho

Dong-Yun Kim

Chang-Hyun Park

Young-Sool Jin

Tae-Hun Lim

Provided is a solution composition for steel sheet surface treatment, comprising 30 wt % to 60 wt % of a trivalent chromium compound containing chromium phosphate (A) and chromium nitrate (B); 0.2 wt % to 0.4 wt % of a rust-inhibiting and corrosion-resisting agent; 0.1 wt % to 0.3 wt % of a molybdenum-based compound; 5 wt % to 10 wt % of a water-soluble cationic urethane resin; 0.5 wt % to 2.0 wt % of a silane coupling agent; and 27.3 wt % to 64.2 wt % of water, a zinc-based plated steel sheet surface-treated with the same, and a manufacturing method therefor, the zinc-based plated steel sheet surface-treated with the solution composition for steel sheet surface treatment containing trivalent chromium may have an excellent effect on corrosion resistance, blackening resistance, fingerprint resistance, oil resistance, and alkali resistance.

Solution composition for steel sheet surface treatment, zinc-based plated steel sheet surface-treated with same, and manufacturing method therefor

Provided is a method of manufacturing an HPF part comprising: preparing a steel sheet comprising C: 0.18% to 0.25%, Si: 0.1% to 1.0%, Mn: 0.9% to 1.5%, P: 0.03% or less, S: 0.01% or less, Al: 0.01% to 0.05%, Cr: 0.05% to 0.5%, Ti: 0.01% to 0.05%, B: 0.001% to 0.005%, N: 0.009% or less, and a balance of Fe and impurities; heating the steel sheet at 550&#xb0; C. to 850&#xb0; C. followed by maintaining at 640&#xb0; C. to 680&#xb0; C., and immersing the steel sheet in a hot dip aluminum plating bath, and a balance of Al and impurities; cooling the plated steel sheet at 15&#xb0; C./s or faster; heating the cooled hot dip aluminum plated steel sheet at 880&#xb0; C. to 930&#xb0; C. followed by maintaining for a certain time; and hot forming the alloyed hot dip aluminum plated steel sheet and quenching at a range of 300&#xb0; C. or lower at the same time.

Method of manufacturing hot press formed parts having excellent powdering resistance

An HPF molding member having a melted aluminum plating layer formed on the surface of a base steel sheet and excellent delamination resistance. The base steel sheet comprises: 0.18-0.25% by weight of C; 0.1-1.0% by weight of Si; 0.9-1.5% by weight of Mn; 0.03% by weight or less of P; 0.01% by weight or less of S; 0.01-0.05% by weight of Al; 0.05-0.5% by weight of Cr; 0.01-0.05% by weight of Ti; 0.001-0.005% by weight of B; 0.009% by weight or less of N; and the balance Fe and other impurities. The plating layer consists of a soft diffusion layer and a hard alloy layer, the hard alloy layer having a tau layer irregularly and non-continuously dispersed and distributed on the inside thereof at 10% or more of the entire area fraction. The difference in hardness between the alloy layer and the diffusion layer is 400 (Hv) or less.

Hot press formed article having excellent delamination resistance and method for manufacturing the same

Provided is a hot press-formed (HPF) member with excellent powdering resistance at the time of press forming. The HPF member includes a hot-dip coating layer containing Al on a surface of a base steel sheet. The base steel sheet includes, based on wt %, 0.18-0.25% of C, 0.1-1.0% of Si, 0.9-1.5% of Mn, 0.03% or less of P, 0.01% or less of S, 0.01-0.05% of Al, 0.05-0.5% of Cr, 0.01-0.05% of Ti, 0.001-0.005% of B, 0.009% or less of N, the balance Fe, and the other impurities. The hot-dip coating layer comprises a soft diffusion layer and a hard alloy layer. The alloy layer has a Tau phase in the range of 10-30%, in terms of area percent.

Hot press formed parts having excellent powdering resistance during hot press forming

Provided is an aluminum coated steel sheet having excellent oxidation and heat resistance. The aluminum coated steel sheet includes an aluminum coating layer and an alloy layer. The aluminum coating layer is formed on a surface of a steel sheet which includes 0.001 to 0.015 wt % of carbon (C), 0.05 to 0.3 wt % of silicon (Si), 0.1 to 0.6 wt % of manganese (Mn), 0.01 to 0.05 wt % niobium (Nb), 0.01 wt % or less of phosphorus (P), 0.01 wt % or less of sulfur (S), 0.1 wt % or less of soluble aluminum (Al), 0.05 to 0.5 wt % of copper (Cu), 0.05 to 0.5 wt % nickel (Ni), 0.001 to 0.01 wt % of nitrogen (N), and the balance of Fe and inevitable impurities. The alloy layer includes an intermetallic compound at an interface between the steel sheet and the aluminum coating layer.

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Pohang-si, South Korea

Dae-Chul Bae