Abstract: Provided is a steel sheet which is suitably used for an automobile structural member, etc., and more specifically, to a steel sheet having excellent uniform elongation and strain hardening rate, while having high strength; and a method for producing same. The steel sheet includes, by wt %, 0.08 to 0.15% of carbon (C), 1.2% or less (excluding 0%) of silicon (Si), 1.4 to 2.4% of manganese (Mn), 1.0% or less of chromium (Cr), 0.1% or less (excluding 0%) of phosphorus (P), 0.01% or less (excluding 0%) of sulfur(S), 1.0% or less (excluding 0%) of aluminum (sol.Al), 0.01% or less (excluding 0%) of nitrogen (N), 0.05% or less (excluding 0%) of antimony (Sb), 0.008% or less of titanium (Ti), 0.008% or less of niobium (Nb), and a balance of Fe and unavoidable impurities.

Abstract: A material control system for cold rolled steel sheets, according to an embodiment of the present invention, comprises: a programmable logic controller that obtains process data about already produced cold rolled steel sheets; a process controller that controls a manufacturing process of cold rolled steel sheets according to the process data from the programmable logic controller; a model generation unit that learns a set of learning data in advance and generates a prediction model for predicting a longitudinal material of a cold rolled steel sheet to be produced; and a production management system that transmits and receives information to and from the process controller, receives a prediction value from the prediction model generated by the model generation unit, and manages production of the cold rolled steel sheet being produced.

Abstract: A material control system for cold rolled steel sheets, according to an embodiment of the present invention, comprises: a programmable logic controller that obtains process data about already produced cold rolled steel sheets; a process controller that controls a manufacturing process of cold rolled steel sheets according to the process data from the programmable logic controller; a model generation unit that learns a set of learning data in advance and generates a prediction model for predicting a widthwise material of a cold rolled steel sheet to be produced; and a production management system that transmits and receives information to and from the process controller, receives a prediction value from the prediction model generated by the model generation unit, and manages production of the cold rolled steel sheet.

Abstract: Provided is an ultra-high-strength cold-rolled steel sheet having excellent yield strength and bending properties, which can be used as a structural component for automobiles such as a member, a seat rail, and a pillar, and a method for manufacturing same. The steel sheet includes: by weight: C: 0.03 to 0.12%, Si: 0.03 to 0.30%, Mn: 2.1 to 2.9%, Al: 0.005 to 0.07%, Nb: 0.01 to 0.08%, Ti: 0.005 to 0.08%, B: 0.0005 to 0.005%, Cr: 0.7 to 1.4%, Mo: 0.005 to 0.10%, N: 0.008% or less (excluding 0%), with a balance of Fe and inevitable impurities. A microstructure thereof includes by area, fresh martensite: 4 to 19%, a sum of tempered martensite and bainite: 78 to 95%, and retained austenite: 0.2 to 2.0%. An average grain size of the microstructure is 0.5 to 6 ?m.

Abstract: Provided is a high-strength steel sheet having excellent crashworthiness and formability. The steel sheet includes: by wt %, carbon (C): 0.06 to 0.2%, silicon (Si): 0.4 to 1.4%, manganese (Mn): 1.8 to 3.0%, aluminum acid (Sol.Al): 1.0% or less, molybdenum (Mo): 0.4% or less, chromium (Cr): 1.0% or less, antimony (Sb): 0.06% or less, boron (B): 0.01% or less, phosphorus (P): 0.1% or less, sulfur(S): 0.01% or less, and a balance of Fe and unavoidable impurity elements. The steel sheet has a microstructure comprising, 40 to 80% of a sum of an area fractions of tempered martensite and bainite, 3 to 15% of retained austenite, and a balance of ferrite and fresh martensite. In the retained austenite, a share (ATM+B/AT) of retained austenite (ATM+B) adjacent to tempered martensite and bainite among a total retained austenite fraction (AT) is 90% or more.

Abstract: Provided is a steel sheet suitably used for an automobile structural member and the like, and more particularly, to a steel sheet having high strength and excellent formability that may prevent processing defects such as cracks or wrinkles occurring during the press-forming, and a method for producing the same.

Abstract: Provided is a high-strength hot-dip galvanized steel sheet having excellent ductility and formability. The hot-dip galvanized steel sheet contains, by wt %, 0.06 to 0.16% of carbon (C), 0.8% or less (excluding 0%) of silicon (Si), 2.1 to 2.7% of manganese (Mn), 0.4% or less (excluding 0%) of molybdenum (Mo), 1% or less (excluding 0%) of chromium (Cr), 0.1% or less (excluding 0%) of phosphorus (P), 0.02% or less of sulfur (S), 1% or less (excluding 0%) of aluminum (sol.Al), 0.001 to 0.04% of titanium (Ti), 0.001 to 0.04% of niobium (Nb), 0.01% or less (excluding 0%) of nitrogen (N), 0.01% or less of boron (B), 0.05% or less of antimony (Sb), and a balance of Fe and unavoidable impurities.

Abstract: Provided is a method for manufacturing an ultra high-strength and high-ductility steel sheet having an excellent yield ratio. The method includes: heating a slab in a temperature range of 1050 to 1300° C.; finish hot rolling the heated slab in a temperature range of 800° C. to 1000° C.; winding the hot-rolled steel sheet in a temperature range of 50° C. to 750° C.; cold rolling the wound hot-rolled steel sheet at a reduction rate of 15% or higher after pickling; and annealing the cold-rolled steel sheet in a temperature range of 600° C. to 720° C. for 10 sec to 3,600 sec, or annealing in a temperature range of higher than 720° C. and 900° C. or lower for 10 sec to 3,600 sec and cooling, followed by a second annealing in a temperature range of 480° C. to 700° C. for 10 sec to 3,600 sec.

Abstract: 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.

Abstract: The present invention relates to a hot-rolled steel sheet that can be suitably applied to an automobile chassis structure member or the like and, more specifically, to an ultrahigh-strength hot-rolled steel sheet having tensile strength of 1180 MPa or more, excellent formability, and uniform material distribution in the steel sheet, and a manufacturing method therefor.

Abstract: 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.

Abstract: The present invention relates to: a high-strength cold-rolled steel sheet having excellent quality and low mechanical property deviation; and a manufacturing method therefor. More particularly, the present invention relates to: a high-strength cold-rolled steel sheet that can be suitably used for automotive parts by ensuring high strength and elongation with little surface defects and low mechanical property deviation; and a manufacturing method therefor.

Abstract: Provided is a high-strength cold-rolled steel sheet having excellent surface quality and low material variation, and a method for manufacturing same. More specifically, the present invention pertains to: a high-strength cold-rolled steel sheet which has few surface defects and little material deviation, as well as high strength and elongation, and is thus suitable for use in automotive parts; and a method for manufacturing same.

Abstract: 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.

Abstract: Provided is a high-strength cold-rolled steel sheet having excellent surface quality and low mechanical property deviation; and a manufacturing method thereof and, more particularly, to: a high-strength cold-rolled steel sheet that can be suitably used for automotive parts by ensuring high strength and elongation with little surface defects and low mechanical property deviation; and a manufacturing method thereof.

Abstract: Provided is an ultra-high-strength cold-rolled steel sheet having excellent yield strength and bending properties, which can be used as a structural component for automobiles such as a member, a seat rail, and a pillar, and a method for manufacturing same. The steel sheet includes: by weight: C: 0.03 to 0.12%, Si: 0.03 to 0.3 Mn: 2.1 to 2.9%, Al: 0.005 to 0.07%, Nb: 0.01 to 0.08%, Ti: 0.005 to 0.08%, B: 0.0005 to 0.005%, Cr: 0.7 to 1.4%, Mo: 0.005 to 0.10%, N: 0.008% or less (excluding 0%), with balance of Fe and inevitable impurities. A microstructure thereof includes by area, fresh martensite: 4 to 19%, a sum of tempered martensite and bainite: 78 to 95%, and retained austenite: 0.2 to 2.0%. An average grain size of the microstructure is 0.5 to 6 ?m.

Abstract: Provided is a high-strength hot-dip galvanized steel sheet having excellent ductility and formability. The hot-dip galvanized steel sheet contains, by wt %, 0.06 to 0.16% of carbon (C), 0.8% or less (excluding 0%) of silicon (Si), 2.1 to 2.7% of manganese (Mn), 0.4% or less (excluding 0%) of molybdenum (Mo), 1% or less (excluding 0%) of chromium (Cr), 0.1% or less (excluding 0%) of phosphorus (P), 0.02% or less of sulfur (S), 1% or less (excluding 0%) of aluminum (sol.Al), 0.001 to 0.04% of titanium (Ti), 0.001 to 0.04% of niobium (Nb), 0.01% or less (excluding 0%) of nitrogen (N), 0.01% or less of boron (B), 0.05% or less of antimony (Sb), and a balance of Fe and unavoidable impurities.

Abstract: Provided are an ultra-high strength cold rolled steel sheet having excellent bendability, and a method of manufacturing the same. The steel sheet includes 0.06 to 0.17% of C, 0.1 to 0.8% of Si, 1.9 to 2.9% of Mn, 0.005 to 0.07% of Nb, 0.004 to 0.05% of Ti, 0.0004 to 0.005% of B, 0.20% or less (excluding 0%) of Cr, and 0.04 to 0.45% of Mo, with a balance of Fe and other unavoidable impurities. a microstructure of the steel sheet includes, by area: 80 to 98% of tempered martensite and a balance of fresh martensite, bainite, ferrite, and residual austenite. An average length of lath short axis of the tempered martensite is 500 nm or less.

Abstract: Provided is an ultra-high strength steel sheet having excellent ductility including, 0.1 to 0.2% of carbon (C), 0.1 to 1.0% of silicon (Si), 2.0 to 3.0% of manganese (Mn), 1.0% or less of aluminum (Al), 1.0% or less of chromium (Cr), 0.5% or less of molybdenum (Mo), 0.1% or less of titanium (Ti), 0.1% or less of niobium (Nb), 0.1% or less of antimony (Sb), 0.05% or less of phosphorus (P), 0.02% or less of sulfur (S), 0.02% or less of nitrogen (N), and a balance of Fe and unavoidable impurities. The steel sheet satisfies the following: 1110[C]+41.5[Si]+575[Mn]?1092[Al]?3590[Nb]?5181[Ti]+258[Cr]+664 [Mo]?1380; 2853 [C]+95 [Si]+309 [Mn]?153 [Al]+4661 [Nb]?780[Ti]+210[Cr]+457[Mo]?1300; and ?29[C]+0.6[Si]?7.3[Mn]+7.8[Al]?145.2[Nb]+62.6[Ti]?3.3[Cr]?2.2[Mo]??24.

Abstract: Provided is a steel sheet suitably used for an automobile structural member and the like, and more particularly, to a steel sheet having high strength and excellent formability that may prevent processing defects such as cracks or wrinkles occurring during the press-forming, and a method for producing the same.