Posco Co., Ltd

Yu-Mi Ha

Jun-Sung Yeom

Seong-Ho Han

Sang-Deok Kang

Yong-Jin Kim

Sung-Kyu Kim

Un-Hae Lee

Chung-Won Kim

Young-Deok Jung

Sang-Hyun Kim

Yong-Hoon Choi

Young-Ju Kim

Provided are a high-strength galvanized steel sheet having excellent distinctness of image after painting and a manufacturing method therefor. The steel sheet includes: by mass %, 0.003 to 0.005% of C, 0.05% or less of Si, 0.4 to 1.0% of Mn, 0.04 to 0.06% of P, 0.01% or less of S, 0.005% or less of N, 0.1% or less of S. Al, 0.05 to 0.08% of Mo, 0.005 to 0.03% of Ti, 0.02 to 0.035% of Nb, 0.06 to 0.1% of Cu, 0.0015% or less of B, and a balance of Fe and inevitable impurities. The alloy microstructure has ferrite in an amount of 95% by area fraction or greater, and the ferrite has a grain average size of 15 μm or less, with the ultra-fine grain 5 μm or less having an occupancy ratio to 7 to 10% within 1 mm×1 mm area.

High-strength galvanized steel sheet having excellent distinctness of image after painting and manufacturing method therefor

Provided are a high-strength hot-dip galvanized steel sheet with excellent formability and a process for producing same. The steel sheet comprises, in mass %: 0.005 to 0.009% of C; 0.05% or less of Si; 0.3 to 0.8% of Mn; 0.06 to 0.09% of P; 0.01% or less of S; 0.005% or less of N; 0.1% or less of Al; 0.05 to 0.08% of Mo; 0.01 to 0.03% of Ti; 0.03 to 0.045% of Nb; 0.06 to 0.1% of Cu; 0.0015% or less of B; and a balance of Fe and inevitable impurities, and 95% or more of ferrite in terms of area fraction. The ferrite has an average grain size of 15 μm or less, with ultrafine grains of 6 μm or less occupying 5 to 10% in a 1 mm×1 mm, and the steel sheet has a surface nanohardness value of 1 to 1.5 GPa.

High-strength hot-dip galvanized steel sheet with excellent formability and process for producing same

Provided is a plated, ultra-low carbon steel sheet which has excellent strength, formability, and surface properties to allow for the weight lightness of automobiles and a manufacturing method therefor and, more specifically, to a galvanized steel sheet and a manufacturing method therefor, wherein the galvanized steel sheet has high strength and high formability and as such, can be suitably used as a material for an automobile outer body.

Plated steel sheet having excellent strength, formability and surface property and method for manufacturing same

Provided is a plated steel sheet and a method for manufacturing the same, and more particularly, to a zinc-based plated steel sheet having high strength and high formability that may be suitably applied as a material for an automotive outer panel and a method for manufacturing the same.

Plated steel sheet having excellent strength, formability and surface quality, and manufacturing method therefor

Provided are a bake-hardened hot-dip galvanized steel sheet with excellent powdering resistance, and a manufacturing method therefor. The bake-hardened hot-dip galvanized steel sheet comprises, by wt %, 0.0001-0.005% of carbon (C), 0.1-1.2% of manganese (Mn), 0.02% or less of silicon (Si) (excluding 0%), 0.01-0.04% of phosphorus (P), 0.01% or less of sulfur (S) (excluding 0%), 0.01% or less of nitrogen (N) (excluding 0%), 0.01-0.06% of aluminum (sol.Al), 0.003-0.015% of niobium (Nb), 0.0005-0.0035% of boron (B), 0.01-0.1% of chromium (Cr), 0.005-0.05% of molybdenum (Mo), 0.003% or less of titanium (Ti) (excluding 0%), and the balance of Fe and inevitable impurities, and satisfies relationships 1 and 2, wherein the microstructure thereof is ferrite single phase and satisfies relationship 3.

Bake-hardened hot-dip galvanized steel sheet with excellent powdering resistance, and manufacturing method therefor

The present invention relates to a high manganese steel for low temperature applications and a method for manufacturing the same. The high manganese steel contains 0.3 wt % to 0.8 wt % of C, 18 wt % to 26 wt % of Mn, 0.01 wt % to 1 wt % of Si, 0.01 wt % to 0.5 wt % of Al, 0.1 wt % or less of Ti (excluding 0%), 1 wt % to 4.5 wt % of Cr, 0.1 wt % to 0.9 wt % of Cu, 0.03 wt % or less of S (excluding 0%), 0.3 wt % or less of P (excluding 0%), 0.001 wt % to 0.03 wt % of N, 0.004 wt % or less of B (excluding 0%), and a remainder of Fe and other inevitable impurities, wherein a microstructure comprises an austenite single phase structure, and an average grain size of the austenite is 50 &#x3bc;m or less.

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Gwangyang-si, South Korea

Yu-Mi Ha