Abstract: A cold rolled steel sheet, and a method of manufacturing the same, designed to have aging resistance and excellent formability suitable for use in automobile bodies, electronic appliances, and the like. The cold rolled steel sheet comprises in weight %: 0.003% or less of C, 0.003˜0.03% of S, 0.01˜0.1% of Al, 0.02% or less of N, 0.2% or less of P, at least one of 0.03˜0.2% of Mn and 0.005˜0.2% of Cu, and a balance of Fe and other unavoidable impurities. When the steel sheet comprises one of Mn and Cu, the composition of Mn, Cu, and S satisfies at least one relationship: 0.58*Mn/S?10 and 1?0.5*Cu/S?10, and when the steel sheet comprises both Mn and Cu, the composition of Mn, Cu, and S satisfies the relationship: Mn+Cu?0.3 and 2?0.5*(Mn+Cu)/S?20. Participates of MnS, CuS, and (Mn, Cu)S in the steel sheet have an average size of 0.2 ?m or less.

Abstract: A spangle-free, hot-dip galvanized steel sheet, and a method and device for manufacturing the same. The hot-dip galvanized steel sheet is characterized in that a solidified zinc crystal of hot-dip galvanized layer has an average crystalline texture particle diameter of 10 to 88 ?m and there is no solidification traces of dendrites upon observing under a microscope at a magnification of 100×. The method comprises dipping a steel sheet in a bath of a zinc-coating solution containing 0.13 to 0.3% by weight of aluminum; air-wiping the steel sheet to remove an excess of the coating solution; spraying water or an aqueous solution on the air-wiped steel sheet, using a steel sheet temperature in the range of a hot-dip galvanization temperature to 419 ° C. as a spray initiation temperature and using a steel sheet temperature in the range of 417 ° C. to 415 ° C.

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 handenability.

Abstract: A cold rolled steel sheet, and a method of manufacturing the same, designed to have aging resistance and excellent formability suitable for use in automobile bodies, electronic appliances, and the like. The cold rolled steel sheet comprises in weight %: 0.003% or less of C, 0.003˜0.03% of S, 0.01˜0.1% of Al, 0.02% or less of N, 0.2% or less of P, at least one of 0.03˜0.2% of Mn and 0.005˜0.2% of Cu, and a balance of Fe and other unavoidable impurities. When the steel sheet comprises one of Mn and Cu, the composition of Mn, Cu, and S satisfies at least one relationship: 0.58*Mn/S?10 and 1?0.5*Cu/S?10, and when the steel sheet comprises both Mn and Cu, the composition of Mn, Cu, and S satisfies the relationship: Mn+Cu?0.3 and 2?0.5*(Mn+Cu)/S?20. Participates of MnS, CuS, and (Mn, Cu)S in the steel sheet have an average size of 0.2 ?m or less.

Abstract: A spangle-free, hot-dip galvanized steel sheet, and a method and device for manufacturing the same. The hot-dip galvanized steel sheet is characterized in that a solidified zinc crystal of hot-dip galvanized layer has an average crystalline texture particle diameter of 10 to 88 ?m and there is no solidification traces of dendrites upon observing under a microscope at a magnification of 100×. The method comprises dipping a steel sheet in a bath of a zinc-coating solution containing 0.13 to 0.3% by weight of aluminum; air-wiping the steel sheet to remove an excess of the coating solution; spraying water or an aqueous solution on the air-wiped steel sheet, using a steel sheet temperature in the range of a hot-dip galvanization temperature to 419° C. as a spray initiation temperature and using a steel sheet temperature in the range of 417° C. to 415° C.

Abstract: A bake-hardenable cold rolled steel sheet, and a method of manufacturing the same, designed to have bake hardenability and excellent formability suitable for automobile bodies, and the like. The steel sheet comprises 0.003˜0.005% C, 0.003˜0.03% S, 0.01˜0.1% Al, 0.02% or less N, 0.2% or less P, 0.03˜0.2% Mn and/or 0.005˜0.2% Cu, and the balance of Fe and other unavoidable impurities in terms of weight %. When it comprises one of Mn and Cu, the composition of Mn, Cu, and S satisfies one of relationships: 0.58*Mn/S?10 and 1?0.5*Cu/S?10. When it comprises both Mn and Cu, the composition satisfies the relationships: Mn+Cu?0.3 and 2?0.5*(Mn+Cu)/S?20. MnS, CuS, and (Mn, Cu)S precipitates have an average size of 0.2 ?m or less. The steel sheets allow the content of solid solution to be controlled by fine MnS, CuS, (Mn, Cu)S precipitates, providing improved bake hardenability, formability, yield strength, and yield strength-ductility balance.

Abstract: The steel plate is manufactured from a composition comprising C, N and S in an amount of 0.0150% by weight or less in total; Mn in an amount of 0.2 to 0.8% by weight; Al inan amount of 0.6% by weight or less; Si in an amount of 0.4% by weight or less; Cu and/or Sn in an amount of 0.1 to 0.6% by weight in total; and Fe for the remainder, and inevitably present elements, whereby the steel plate can show excellent electromagnetic shield effect and hot-dip galvanization properties.

Abstract: A steel plate and a hot-dip galvanized steel plate, superior in terms of high electromagnetic shield capacity. The steel plate is prepared from a composition comprising C, N and S in an amount of 0.150% by weight or less in total; Mn in an amount of 0.1 to 1.0% by weight; Si in an amount of 0.5% by weight or less; Al in an amount of 1.0% by weight or less; P in an amount of 0.06% by weight or less; and Fe for the remainder, and inevitable elements, and shows a yield strength of 18 kg/mm2 or higher, and an elongation of 40% or higher. The hot-dip galvanized steel plate is prepared from a composition comprising C, N and S in an amount of 0.0150 % by weight or less in total; Mn in an amount of 0.2 to 0.8% by weight; Al in an amount of 0.6% by weight or less; Si in an amount of 0.4% by weight or less; P in an amount of 0.06% by weight or less, with the proviso that the sum of Mn, Al, Si and P amounts to 0.2-1.0% by weight; and Fe for the remainder, and inevitably present elements.

Abstract: Disclosed are far-infrared emission powders and resin-coated steel plates with antibacterial activity and far-infrared emission properties. In addition to being 0.9 or higher in emissivity, the far-infrared emission powders are inhibitory against the growth of bacteria, with a pH value of 7.5-10.5 in its saturate aqueous solution. A coating material comprising 5-100 parts by weight of the powder per 100 parts by weight of a resin is coated to a dry thickness of 5-60 &mgr;m on an electromagnetic shield steel plate without interruption of the intrinsic electromagnetic shield properties of the steel plate.

Abstract: Disclosed are far-infrared emission powders and resin-coated steel plates with antibacterial activity and far-infrared emission properties. In addition to being 0.9 or higher in emissivity, the far-infrared emission powders are inhibitory against the growth of bacteria, with a pH value of 7.5-10.5 in its saturate aqueous solution. A coating material comprising 5-100 parts by weight of the powder per 100 parts by weight of a resin is coated to a dry thickness of 5-60 &mgr;m on an electromagnetic shield steel plate without interruption of the intrinsic electromagnetic shield properties of the steel plate.

Abstract: Disclosed are a steel plate and a hot-dip galvanized steel plate, superior in terms of high electromagnetic shield capacity. The steel plate is prepared from a composition comprising C, N and S in an amount of 0.150% by weight or less in total; Mn in an amount of 0.1 to 1.0% by weight; Si in an amount of 0.5% by weight or less; Al in an amount of 1.0% by weight or less; P in an amount of 0.06% by weight or less; and Fe for the remainder, and inevitable elements, and shows a yield strength of 18 kg/mm2 or higher, and an elongation of 40% or higher. The hot-dip galvanized steel plate is prepared from a composition comprising C, N and S in an amount of 0.0150% by weight or less in total; Mn in an amount of 0.2 to 0.8% by weight; Al in an amount of 0.6% by weight or less; Si in an amount of 0.4% by weight or less; P in an amount of 0.06% by weight or less, with the proviso that the sum of Mn, Al, Si and P amounts to 0.2˜1.0% by weight; and Fe for the remainder, and inevitably present elements.

Abstract: Disclosed are a high-strength steel plate with excellent electromagnetic shield capacity and a method for manufacturing the same. The steel plate is manufactured from a composition comprising C, N and S in an amount of 0.0150% by weight or less in total; Mn in an amount of 0.2 to 0.8% by weight; Al in an amount of 0.6% by weight or less; Si in an amount of 0.4% by weight or less; Cu and/or Sn in an amount of 0.1 to 0.6% by weight in total; and Fe for the remainder, and inevitably present elements, whereby the steel plate can show excellent electromagnetic shield effect and hot-dip galvanization property.

Abstract: An alloying system for a galvanized steel sheet, using an induction heating coil, wherein the temperature of the steel sheet in an induction heating furnace is measured based on the impedance of a high frequency heater, and the amount of heating is controlled by feedback, to form an alloy layer of the steel sheet.

Abstract: An apparatus and a method for coating zinc on steel sheets for use on automobiles and electronic apparatuses are disclosed. A fluidized bed forming chamber is provided to fluidize zinc powders in carrying out a zinc coating on a heated steel sheet, so that not only a uniformly coated layer but also a thick coated layer can be obtained. The apparatus for continuously coating zinc on a steel sheet according to the present invention includes a zinc coating chamber for forming a fluidized bed of zinc powders, for passing a heated steel sheet through the fluidized bed of the zinc powders, and for making the zinc powders melt-adhere on the steel sheet during its passing through the fluidized bed. A fluidized bed forming chamber forms a fluidized bed of the zinc powders by making the zinc powders suspended by spouting a gas.