Posco

Posco Co., Ltd

Postech Academy-industry Foundation

Kyoo-Young Lee

Jin-Keun Oh

Jong-Sang Kim

Joo-Hyun Ryu

Sea-Woong Lee

Jai-Hyun Kwak

Won-Hwi Lee

Ki-Cheol Kang

Young-Roc Im

Hang-Sik Cho

Sung-hak Lee

Man-Young Park

Han-Chul Shin

Gyo-Sung Kim

Chang-Hoon Lee

Kee-Cheol Park

Kwang-Geun Chin

Kyong-Su Park

Chung-Hwan Lee

Jae-Kon Lee

Dong-Seoug Sin

Tae-Kyo Han

Kang-Min Lee

Jea-Chun Jeon

Nack-Joon Kim

Jong-Ho Kim

Yong-Joo Kim

Seok-su Sohn

Bruno C De Cooman

Jae-Hwa Ryu

Jae-Chun Jeon

Seon-Jong Lee

Eun-Jung Seo

Se-Don Choo

Byun-Mok Hwang

Sim-Kun Min

Hyung-Soo Lee

Min-Chul Jo

Yeong-Woo Jeon

Sung-Hak Lee

An ultra high strength and high ductility steel sheet having an excellent yield ratio contains, in weight %, 0.1-0.3% of carbon (C), 2% or less of silicon (Si), 6-10% of manganese (Mn), 0.05% or less of phosphorus (P), 0.02% or less of sulfur (S), 0.02% or less of nitrogen (N), 0.5% or less (excluding 0%) of aluminum (Al), and the balance Fe and inevitable impurities, and further contains at least one selected from the group consisting of 0.1% or less of titanium (Ti), 0.1% or less of niobium (Nb), 0.2% or less of vanadium (V), and 0.5% or less of molybdenum (Mo), wherein the ultrahigh-strength and high-ductility steel sheet comprises 20 area % or more of residual austenite as a microstructure, the average aspect ratio of the residual austenite being 2.0 or higher.

Ultra high strength and high ductility steel sheet having excellent yield ratio and manufacturing method for same

Provided is a zinc plated steel sheet having excellent spot weldability and a manufacturing method thereof. The zinc plated steel sheet includes a steel sheet and a zinc plated layer formed on the surface of the steel sheet, wherein the ratio (a/b) between a widthwise average value (a) of thickness of an internal oxidized layer and a widthwise standard deviation (b) of thickness of the internal oxidized layer in the steel sheet may be 1.5 or more.

Zinc plated steel sheet having excellent spot weldability and manufacturing method thereof

One aspect of the present invention relates to an ultrahigh-strength steel sheet having an excellent yield ratio, comprising, by wt %, 0.3-0.5% of C, 2.0% (excluding 0%) of Si, 3.0-6.5% of Mn, 0.02% or less of P, 0.01% or less of S, 0.01-3.0% of Al, 0.02% or less (excluding 0%) of N, and the balance of Fe and other inevitable impurities, and a microstructure comprises 5-30% of remaining austenite by area fraction and comprises 5% or less of secondary martensite.

Ultrahigh-strength steel sheet having excellent yield ratio, and manufacturing method therefor

The present disclosure relates to a high-strength hot-dip galvanized steel sheet having excellent surface quality and electrical resistance spot weldability, and a method for manufacturing the same. A galvanized steel sheet according to an aspect of the present disclosure is a galvanized steel sheet including a base steel sheet and a zinc-based plating layer formed on a surface of the base steel sheet, wherein a ratio (a/b) of a hardness of a surface layer portion (a) to a hardness of an internal portion (b) of the base steel sheet may be less than 0.95.

Advanced high strength zinc plated steel sheet having excellent surface quality and electrical resistance spot weldability

The present invention relates to an automotive steel sheet and, more specifically, provides: an ultrahigh-strength and high-ductility steel sheet ensuring ultrahigh strength and high ductility and, simultaneously, having excellent cold formability due to a high yield strength ratio, and improved collision characteristics.

Ultrahigh-strength and high-ductility steel sheet having excellent cold formability

Provided is an ultra-high-strength steel sheet having an excellent hole expandability and yield ratio, including, in terms of wt %: 0.05-0.2% of carbon (C); 2.0% or less of silicon (Si); 4.1-9.0% of manganese (Mn); 0.05% or less (excluding 0%) of phosphorus (P); 0.02% or less (excluding 0%) of sulfur (S); 0.5% or less (excluding 0%) of aluminum (Al); 0.02% or less (excluding 0%) of nitrogen (N); and a balance of iron (Fe) and other inevitable impurities, wherein the following Equation 1 is satisfied, and wherein microstructures includes, in volume percentage, 10-30% or retained austenite, 50% or more of annealed martensite, and 20% or less of other phases including alpha martensite and epsilon martensite, Equation 1: C/12+Ti/48+Nb/93+V/51+Mo/96&#x2265;0.015.

Ultra-high-strength steel sheet having excellent hole expandability and yield ratio, and method of manufacturing the same

Provided is a steel sheet having excellent resistance to liquid metal embrittlement cracks and a method for manufacturing the same. The steel sheet includes, by weight %, 0.04% to 0.35% of C, 0.99% or less of Al+Si, 3.5% to 10% of Mn, 0.05% or less of P (excluding 0%), 0.02% or less of S (excluding 0%), and 0.02% or less of N (excluding 0%) with a remainder of Fe and other inevitable impurities, wherein the steel sheet comprises a microstructure comprising at least 10% of residual austenite, at least 60% of annealed martensite and 20% or less of alpha martensite and epsilon martensite, by volume fraction, and an average thickness of a Mn-depleted layer is at least 0.5 &#x3bc;m from a product surface.

Steel sheet having excellent resistance to liquid metal embrittlement cracks and method for manufacturing the same

Provided is an ultra-high strength steel plate for automobiles and, more specifically, to an ultra-high strength steel plate having high formability and hole expandability, and a method for manufacturing the ultra-high strength steel plate. The ultra-high strength steel plate includes: by wt %, carbon (C): 0.04% to 0.17%, silicon (Si): 2% or less, manganese (Mn): 4% to 10%, phosphorous (P): 0.05% or less (excluding 0%), sulfur (S): 0.02% or less (excluding 0%), aluminum (Al): 0.5% or less (excluding 0%), nitrogen (N): 0.02% or less (excluding 0%), and a balance of iron (Fe) and inevitable impurities. Carbon (C) and manganese (Mn) satisfy Formula C+(Mn/25)&#x2264;0.46. The ultra high strength steel plate has a microstructure comprising retained austenite in a volume fraction of 20% or greater and annealed martensite in a volume fraction of 50% or greater.

Ultra-high strength steel plate having excellent formability and hole-expandability, and method for manufacturing same

Provided is a hot rolled steel sheet having excellent strength and elongation. The hot rolled steel sheet contains, by wt %: carbon (C): 0.05% or more and less than 0.4%, manganese (Mn): 10% to 15%, aluminum (Al): 2% or less, silicon (Si): 0.1 to 2%, molybdenum (Mo): 0.5% or less (excluding 0), vanadium (V): 0.5% or less (excluding 0), phosphorus (P): 0.01% or less, sulfur (S): 0.01% or less, and a remainder of iron (Fe) and inevitable impurities. The hot rolled steel sheet has a microstructure of the hot rolled steel sheet containing, by area %, tempered martensite: 50% to 70%, secondary martensite: 20% or less (excluding 0), epsilon martensite: 2% or less (excluding 0), and retained austenite: 8% to 30%. The hot rolled steel sheet has a tensile strength of at least 1500 MPa, a yield strength of at least 900 MPa and elongation of at least 20%.

Hot rolled steel sheet having excellent strength and elongation

Provided is an ultrahigh-strength steel sheet for a vehicle and, more specifically, to an ultrahigh-strength and high-ductility steel sheet having excellent yield ratio and a manufacturing method therefor. Provided is an ultrahigh-strength and high-ductility steel sheet for cold press forming and a manufacturing method therefor, the steel sheet ensuring ultrahigh strength and high ductility since an alloy component of steel and manufacturing conditions are controlled and, simultaneously, having excellent impact characteristics due to a high yield strength ratio (yield ratio). Provided is the steel sheet capable of satisfying formability and impact stability, which are required for a vehicle steel sheet for cold forming, and replacing a conventional steel sheet for hot press forming, thereby reducing manufacturing costs.

Ultra high-strength and high-ductility steel sheet having excellent yield ratio and manufacturing method therefor

Provided is an ultrahigh-strength high-ductility steel sheet having excellent yield strength, comprising, by wt %, 0.04-0.18% of C, 2% or less of Si, 4-10% of Mn, 0.05% or less of P (except 0%), 0.02% or less of S (except 0%), 0.5% or less of Al (except 0%), 0.02% or less of N (except 0%) and the balance of Fe and the other inevitable impurities, wherein Si+Mn satisfies 6-10% and the microstructure comprises, by volume fraction, 12% or more of retained austenite and 60% or more of annealed martensite.

Ultrahigh-strength high-ductility steel sheet having excellent yield strength, and manufacturing 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: a high-strength steel sheet used for construction materials and transportation means such as vehicles and trains and, more specifically, to a high-strength cold rolled steel sheet having excellent ductility, a hot-dip galvanized steel sheet, and a method for manufacturing the same.

High-strength cold rolled steel sheet having excellent ductility, hot-dip galvanized steel sheet and method for manufacturing same

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 ferritic lightweight high-strength steel sheet having excellent stiffness and ductility and a method of manufacturing the same. The steel sheet including 0.02 wt % to 0.1 wt % of carbon (C), 4 wt % to 15 wt % of manganese (Mn), 4 wt % to 10 wt % of aluminum (Al), 2.0 wt % or less (excluding 0) of silicon (Si), 0.01 wt % to 0.3 wt % of titanium (Ti), 0.005 wt % to 0.2 wt % of antimony (Sb), and iron (Fe) as well as unavoidable impurities as a remainder, and having a value of 0.25&#xd7;Ti/C ranging from 0.17 to 1.0 and a value of Mn/Al&#xd7;Log(C&#xd7;Ti&#xd7;10000) ranging from 1.0 to 10.

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Gwangyang-si, South Korea

Kyoo-Young Lee