Posco

Posco Co., Ltd

Man-Young Park

Kyoo-Young Lee

Sang-Ho Han

Sung-Il Kim

Joo-Hyun Ryu

Jai-Hyun Kwak

Hang-Sik Cho

Kwang-Geun Chin

Min-Seo Koo

Tae-Jin Song

Jae-Hoon Lee

Won-Tae Cho

Jong-Chan Park

Rho-Bum Park

Eul-Yong Choi

Jong-Kweon Kim

Jin-Hee Chung

Ho-Seok Kim

Provided are a high-strength steel sheet and a method for manufacturing same, the high-strength steel sheet including: an alloy system having C, Si, Mn, Cr, Al, Nb, Ti, B, P, S, N, and the remainder of Fe and other inevitable impurities. The contents of C, Si, and Al satisfy equation (1) below. The microstructure includes, by an area fraction, greater than 50% to 70% or less of tempered martensite, and the remainder of residual austenite, fresh martensite, ferrite, and bainite, in which a cementite phase as a second phase is precipitated and distributed in an area fraction of 1-3% between bainite laths, or at a lath on the tempered martensite or grain boundaries. [Equation (1)][C]+([Si]+[Al])/5; 0.35 wt. % (wherein [C], [Si], and [Al] denote wt % of C, Si, and Al, respectively.)

High-strength steel sheet and manufacturing method thereof

A clad steel plate, having excellent strength and formability, may include a base material; and a cladding material provided on both side surfaces of the base material, wherein the base material is austenitic high-manganese steel comprising, by weight, 0.3% to 1.4% of C, 12% to 25% of Mn, and a remainder of Fe and inevitable impurities, the cladding material is a martensitic carbon steel comprising, by weight, 0.09% to 0.4% of C, 0.3% to 4.5% of Mn, and a remainder of Fe and inevitable impurities.

Clad steel plate having excellent strength and formability, and production method therefor

Provided is a method of continuously annealing a strip. The method includes: firstly heating a strip in a first heating zone; firstly cooling the firstly heated strip or maintaining the firstly heated strip at a constant temperature in a first cooling or constant temperature maintaining zone; secondarily heating and soaking the strip, firstly cooled or remaining at the constant temperature, in a second heating and soaking zone; and secondarily cooling the strip, secondarily heated and soaked, in a second cooling zone.

Method of continuously annealing a strip

The present invention relates to an apparatus for continuous annealing of a strip, capable of manufacturing a high-strength and highly ductile cold-rolled steel sheet having both excellent strength and ductility, and to a method for continuous annealing of a strip. The continuous annealing apparatus, according to the present invention, is capable of continuous annealing by cooling after heating, and then reheating, unlike an existing continuous annealing apparatus which heats only once and then cools or provides an overaging treatment. As a result, the continuous annealing apparatus, according to the present invention, can preliminarily render a homogeneous texture or control the texture as desired, and then perform another reheating heat treatment to stabilize the texture or control the shape thereof to a desired state. Also, provided is a continuous annealing apparatus and a continuous annealing method using the apparatus, the continuous annealing apparatus also capable of manufacturing high-strength steel having excellent processability and strength by using a low alloy, and capable of manufacturing a zinc-plated strip having excellent plated surfaces by controlling the thickness of elements and oxides enriched on the surface of the strip.

Apparatus for continuous annealing of strip and method for continuous annealing of same

Provided is a method for producing plated steel sheet by means of an annealing device which includes at least one section and in which the at least one section is filled with a gas constituting a non-reducing atmosphere or a weakly reducing atmosphere to substantially improve the quality of plating onto hot-dipped steel sheet, including the plating properties, alloying properties, anti-pickup properties, plating adhesion properties, anti-flaking properties, anti-cratering properties and anti-ash properties, by using prior-art annealing equipment and heat-treatment cycle without any additional oxidation-reduction heat treatment process or large quantities of high-cost alloying elements.

Production method for plated steel sheet using a steel sheet annealing device

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Gwangyang-si, South Korea

Man-Young Park