Jfe Steel Corporation

Daisuke Harako

Yoshitsugu Suzuki

Yuji Tanaka

Yasunobu Nagataki

Yusuke Fushiwaki

Tetsuya Iwata

Hideki Nagano

A high-strength galvanized steel sheet includes a base steel sheet having a specific chemical composition and a zinc coating layer disposed on the surface of the base steel sheet in a coating weight per side of 20 g/mto 120 g/m, wherein the amount of hydrogen measured by a specific method is 0.05 mass ppm to 0.40 mass ppm; and I/Iand I/Icalculated by a specific method are not more than 2.0 and not more than 3.0, respectively.

High-strength galvanized steel sheet and method of manufacturing the same

A high strength galvanized steel sheet has a composition including, C: 0.02% or more and 0.30% or less, Si: 0.01% or more and 2.5% or less, Mn: 0.1% or more and 3.0% or less, P: 0.003% or more and 0.08% or less, S: 0.01% or less, Al: 0.001% or more and 0.20% or less, Ti: 0.03% or more and 0.40% or less and the balance being Fe and inevitable impurities, and a zinc-coated layer having a coating weight per surface of 20 g/mor more and 120 g/mor less. The concentration ratio of C to Ti (C/Ti) in a portion within 10 &#x3bc;m from the surface of the base steel sheet is 0.8 or more and 1.5 or less, and the total amount of oxides of one or more selected from Fe, Si, Mn, P, Al and Ti formed in a surface portion within 100 &#x3bc;m from the surface of the base steel sheet is 0.05 g/mor less.

High strength galvanized steel sheet and method for manufacturing the same

A galvannealed steel sheet includes a zinc coating layer containing 7 to 15% Fe on the surface of steel sheet including, C: 0.02% to 0.30%, Si: 0.01% to 2.5%, Mn: 0.1% to 3.0%, P: 0.003% to 0.08%, S: not more than 0.01%, Al: 0.001% to 0.20%, one or more selected from Ti: 0.03% to 0.40%, Nb: 0.001% to 0.2%, V: 0.001% to 0.2%, Mo: 0.01% to 0.5% and W: 0.001% to 0.2%. In the zinc coating layer, carbides with average particle size of 1 nm to 20 nm including one or more selected from titanium, niobium, vanadium, molybdenum and tungsten are present with a density of five or more particles per segment that is defined by the thickness of the coating layer and also by dividing a cross section of the coating layer at intervals of 1 &#x3bc;m in a direction perpendicular to the thickness of the coating layer.

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Kawasaki, Japan

Daisuke Harako