Abstract: A steel sheet having high strength and high formability according to an aspect of the present invention includes: % by weight, an amount of 0.12-0.22% of carbon (C); an amount of 1.6-2.4% of silicon (Si); an amount of 2.0-3.0% of manganese (Mn); an amount of 0.01-0.05% of aluminum (Al); an amount greater than 0 and less than or equal to 0.05% of the sum of one or more of titanium (Ti), niobium (Nb) and vanadium (V); an amount of 0.015% or less of phosphorus (P); an amount of 0.003% or less of sulfur (S); an amount of 0.006% or less of nitrogen (N); and the reminder of Fe and inevitable impurities, and has a yield strength (YS) of 850 MPa or greater, a tensile strength (TS) of 1180 MPa or greater, an elongation ratio (EL) of 14% or greater, and a hole expansion ratio (HER) or 30% of greater.

Abstract: Disclosed are a hot-dip galvannealed steel sheet with ultra-high strength and high formability, and a manufacturing method therefor. In an exemplary embodiment, a hot-dip galvannealed steel sheet include: a base steel sheet; and a hot-dip galvannealed layer formed on the surface of the base steel sheet. The base steel sheet includes an amount of 0.05 to 0.15 wt % of carbon (C), an amount greater than 0 and less than or equal to 1.0 wt % of silicon (Si), an amount of 4.0 to 9.0 wt % of manganese (Mn), an amount greater than 0 and less than or equal to 0.6 wt % of aluminum (Al), an amount greater than 0 and less than or equal to 0.02 wt % of phosphorus (P) in, an amount greater than 0 and less than or equal to 0.005 wt % of sulfur (S), an amount greater than 0 and less than or equal to 0.006 wt % of nitrogen (N), and the balance of iron (Fe) and other inevitable impurities.

Abstract: Provided herein is a steel sheet having high strength and high formability according to an aspect of the present invention including, % by weight, an amount of 0.05 to 0.15% of carbon (C), an amount greater than 0 and 0.4% or less of silicon (Si), an amount of 4.0-9.0% of manganese (Mn), an amount of greater than 0 and 0.3% or less of aluminum (Al), an amount of 0.02% or less of phosphorus (P), an amount of 0.005% or less of sulfur (S), an amount of 0.006% or less of nitrogen (N), and the remainder of iron (Fe) and other inevitable impurities. The steel sheet has a microstructure consisting of ferrite and residual austenite. The grain size of the microstructure is 3 ?m or less. The steel sheet has a yield strength (YS) of 800 MPa or greater, a tensile strength (TS) of 980 MPa or greater, an elongation (EL) of 25% or greater, and a hole expansion ratio (HER) of 20% or greater.

Abstract: Provided are a cold rolled steel sheet with ultra-high strength, and a manufacturing method therefor. In an exemplary embodiment, a cold rolled steel sheet with ultra-high strength includes an amount of 0.10 to 0.40 wt % of carbon (C), an amount of 0.10 to 0.80 wt % of silicon (Si), an amount of 0.6 to 1.4 wt % of manganese (Mn), an amount of 0.01 to 0.30 wt % of aluminum (Al), an amount greater than 0 and less than or equal to 0.02 wt % of phosphorus (P), an amount greater than 0 and less than or equal to 0.003 wt % of sulfur (S), an amount greater than 0 and less than or equal to 0.006 wt % of nitrogen (N), an amount greater than 0 and less than or equal to 0.05 wt % of titanium (Ti) in, an amount of 0 to 0.05 wt % of niobium (Nb), an amount of 0.001 to 0.003 wt % of boron (B), and the balance of iron (Fe) and other inevitable impurities, wherein the cold rolled steel sheet has a microstructure comprising tempered martensite and has a 900 bending workability (R/t) of 1.

Abstract: Disclosed herein are a steel sheet having excellent aging resistance and low yield ratio properties, and a method for producing the same. The disclosed sheet comprises, by weight, 0.005-0.06% carbon (C), 0.2% or less silicon (Si), 1.0-2.0% manganese (Mn), 0.08% or less phosphorus (P), 0.01% or less sulfur (S), 0.2-2.0% aluminum (Al), one or more of chromium (Cr) and molybdenum (Mo) in an amount satisfying 0.3?[Cr wt %]+0.3[Mo wt %]?2.0, and 0.008% or less nitrogen (N), with the remainder being iron (Fe) and inevitable impurities, and has a single-phase structure of ferrite in a hot-rolled state, and a two-phase structure of ferrite and martensite in a cold-rolled state.

Abstract: Disclosed are a steel sheet having excellent and a method for producing the same. The disclosed steel sheet comprises, by weight, 0.005-0.06% carbon (C), 0.2% or less silicon (Si), 1.0-2.0% manganese (Mn), 0.01% or less sulfur (S), 0.2-2.0% aluminum (Al), one or more of chromium (Cr) and molybdenum (Mo) in an amount satisfying 0.3?[Cr wt %]+0.3[Mo wt %]?2.0, and 0.008% or less nitrogen (N), with the remainder being iron (Fe) and inevitable impurities, wherein the density of dislocations in the ferrite matrix of the steel sheet is 1×1013/m2 or more.

Abstract: Disclosed herein are a steel sheet having excellent aging resistance and low yield ratio properties, and a method for producing the same. The disclosed sheet comprises, by weight, 0.005-0.06% carbon (C), 0.2% or less silicon (Si), 1.0-2.0% manganese (Mn), 0.08% or less phosphorus (P), 0.01% or less sulfur (S), 0.2-2.0% aluminum (Al), one or more of chromium (Cr) and molybdenum (Mo) in an amount satisfying 0.3?[Cr wt %]+0.3[Mo wt %]?2.0, and 0.008% or less nitrogen (N), with the remainder being iron (Fe) and inevitable impurities, and has a single-phase structure of ferrite in a hot-rolled state, and a two-phase structure of ferrite and martensite in a cold-rolled state.

Abstract: Disclosed are a steel sheet having excellent and a method for producing the same. The disclosed steel sheet comprises, by weight, 0.005-0.06% carbon (C), 0.2% or less silicon (Si), 1.0-2.0% manganese (Mn), 0.01% or less sulfur (S), 0.2-2.0% aluminum (Al), one or more of chromium (Cr) and molybdenum (Mo) in an amount satisfying 0.3?[Cr wt %]+0.3[Mo wt %]?2.0, and 0.008% or less nitrogen (N), with the remainder being iron (Fe) and inevitable impurities, wherein the density of dislocations in the ferrite matrix of the steel sheet is 1×1013/m2 or more.