Abstract: A high-manganese hot-dip coated steel sheet is disclosed which provides high corrosion resistance, high ductility and high strength, mainly used for inner and outer panels of automobiles, and a method of manufacturing the same. The high-manganese hot-dip coated steel sheet includes a substrate steel sheet having a composition of (in weight %) 0.1 to 1.5% of C, 5 to 35% of Mn, and the remainder includes Fe and other unavoidable impurities, and a hot-dip zinc coating layer formed on the substrate steel sheet, the hot-dip zinc coating layer having a composition of (in weight %) 0.1 to 10% of Mn, 5 to 15% of Fe, and the remainder including Zn and other unavoidable impurities.

Abstract: Disclosed is a steel sheet that exhibits an ultra-high strength after hot press forming followed by rapid cooling, and an enhanced yield strength after painting. The steel sheet has a composition comprising 0.1% to 0.5% by weight of C, 0.01% to 1.0% by weight of Si, 0.5% to 4.0% by weight of Mn, 0.1% by weight or less of P, 0.03% by weight or less of S, 0.1% by weight of soluble Al, 0.01% to 0.1% by weight of N, 0.3% by weight or less of W, and the balance Fe and other inevitable impurities. Further disclosed are a hot-pressed part made of the steel sheet and a method for manufacturing the hot-pressed part. The hot-pressed part achieves a high increment in yield strength after heat treatment for painting while ensuring an ultra-high tensile strength. Furthermore, the hot-pressed part exhibits superior adhesion to a coating layer, good surface appearance and improved corrosion resistance after painting.

Abstract: A hot rolled steel sheet used for a bumper reinforceing material or for an impact absorption material in a door of automobiles, and a method for manufacturing the same are disclosed. The steel sheet comprises, by weight%, C: 0.2%˜1%, Mn: 8˜15%, S: 0.05% or less, P: 0.03% or less, and the balance of Fe and other unavoidable impurities. A product of tensile strength and total elongation (TS×ToLEl) of the steel sheet is 24,000 MPa % or more. The method provides a high strength hot rolled steel sheet, which has a high strength-elongation balance value, ensuring excellent workability.

Abstract: Disclosed herein is a Nb—Ti composite IF steel in which fine precipitates, such as CuS precipitates, having a size of 0.2 ?m or less are distributed. The distribution of fine precipitates in the Nb—Ti composite IF steel enhances the yield strength and lowers the in-plane anisotropy index. The nanometer-sized precipitates allow the formation of minute crystal grains. As a result, dissolved carbon is present in a larger amount in the crystal grain boundaries than within the crystal grains, which is advantageous in terms of room-temperature non-aging properties and bake hardenability.

Abstract: Disclosed herein is a Ti-based IF steel in which fine precipitates, such as CuS precipitates, having a size of 0.2 ?m or less are distributed. The distribution of fine precipitates in the Ti-based IF steel enhances the yield strength and lowers the in-plane anisotropy index. The nanometer-sized precipitates allow the formation of minute crystal grains. As a result, dissolved carbon is present in a larger amount in the crystal grain boundaries than within the crystal grains, which is advantageous in terms of room-temperature non-aging properties and bake hardenability.

Abstract: A high-strength isotropic cold-rolled steel sheet having excellent shape-fixability, and a method for manufacturing the same are disclosed. The steel sheet is made using a low-carbon steel comprising a little amounts of Ti to have an r of 1.3 or less, r approaching 1, and a low in-plane anisotropy index (Dr) of 0.15 or less, ensuring excellent shape-fixability so as to be suitable for automotive outer panels which are essentially subjected to deformation in a stretching mode.

Abstract: Disclosed herein are a bake-hardenable high-strength cold-rolled steel sheet, a hot-dipped steel sheet thereof, and a method for manufacturing the same. The steel sheet comprises 0.0016˜0.01% of C; 0.1% or less of Si; 0.2˜1.5% of Mn; 0.05˜0.15% of P; 0.01% or less of S; 0.08˜0.5% of (soluble) Al; 0.0025% or less of N; 0.003˜0.1% of Nb; 0.003% of less of Ti; 0.01˜0.4% of Mo; 0.0005˜0.005% of B; and the balance of Fe and other unavoidable impurities, in terms of weight %. The steel sheet has fine AlN precipitates, and a grain size (ASTM No.) of 9 or more. The AlN precipitates have a grain size, which can suppress grain growth. The steel sheet has enhanced strength, bake hardenability, aging resistance, and secondary work embrittlement resistance.