Abstract: A surface treatment composition for a galvanized steel sheet containing, based on 100 parts by weight of the total solution, 3.0 to 25.0 parts by weight of a silane compound, 0.5 to 5.0 parts by weight of a molybdenum compound, 0.5 to 5.0 parts by weight of a vanadium compound, 0.1 to 3.0 parts by weight of a nickel compound, 0.05 to 1.0 parts by weight of a copper compound, and a remainder of solvent, a surface treatment method for a galvanized steel sheet using the surface treatment composition, and a surface-treated galvanized steel sheet, are provided. Corrosion resistance, blackening resistance, warm water resistance, and conductivity are secured free from concerns regarding the installation of additional equipment for treating chromium, increased manufacturing costs, and environmental pollution.

Abstract: Provided is a hot dip zinc alloy plated steel sheet which is widely used in vehicles, domestic appliances, construction materials or the like and a method for manufacturing the same. A Zn—Al—Mg hot dip zinc alloy plating bath is used for manufacturing the hot dip zinc alloy plated steel strip, and a small amount of Ga or In is added to the plating bath for inhibiting an oxidation reaction of Mg in the plating bath so as to obtain excellent corrosion resistance and external surface of the plated steel sheet which is manufactured at this point.

Abstract: Provided is a descaling device for effectively removing scale formed on a surface of a hot-rolled steel strip (steel sheet). The descaling device, for example, may be configured to include: a device housing disposed in a feed path of a hot-rolled steel strip, a high-pressure fluid supply unit provided to supply a high-pressure fluid to the device housing, an abrasive input unit provided to introduce an abrasive to the device housing, and an abrasive slurry spraying unit provided in the device housing to spray an abrasive slurry of the high-pressure fluid and the abrasive mixed inside the device housing on the steel strip.

Abstract: Provided is a hot dip zinc (Zn) alloy plated steel sheet having excellent corrosion resistance and surface qualities, and a method of manufacturing the same. For this purpose, provided is a high corrosion resistant hot dip Zn alloy plated steel sheet which includes an underlying steel sheet and a hot dip Zn alloy plating layer, wherein a composition of the hot dip Zn alloy plating layer includes 1 to 3 wt % of aluminum (Al), 1.5 to 4.0 wt % of magnesium (Mg), and Zn and unavoidable impurities as a remainder, in which Al+Mg is in a range of 2.5 to 7.0 wt % and Al: (Al+Mg) ratio is in a range of 0.38 to 0.48, and a method of manufacturing the high corrosion resistant hot dip Zn alloy plated steel sheet.

Abstract: Provided are: a surface-treatment composition for galvanised steel sheet, the composition comprising, with respect to 100 parts by weight of solution as a whole, between 3.0 and 25.0 parts by weight of a silane compound, between 0.5 and 5.0 parts by weight of a molybdenum compound, between 0.5 and 5.0 parts by weight of a vanadium compound, between 0.1 and 3.0 parts by weight of a nickel compound, between 0.05 and 1.0 part by weight of a copper compound and a balance of solvent; a method of surface treating a galvanised steel sheet by means of the surface-treatment composition; and a surface-treated galvanized steel sheet. The present invention makes it possible to provide a galvanised steel sheet in which corrosion resistance, blackening resistance, hot-water resistance and electrical conductivity are ensured, without the risk of additional equipment installation problems, increased production cost problems and environmental pollution problems for the purpose of chrome treatment.

Abstract: Provided is a hot dip zinc alloy plated steel sheet which is widely used in vehicles, domestic appliances, construction materials or the like and a method for manufacturing the same. A Zn—Al—Mg hot dip zinc alloy plating bath is used for manufacturing the hot dip zinc alloy plated steel strip, and a small amount of Ga or In is added to the plating bath for inhibiting an oxidation reaction of Mg in the plating bath so as to obtain excellent corrosion resistance and external surface of the plated steel sheet which is manufactured at this point.

Abstract: A method for continuously removing scale from a hot-rolled carbon steel strip includes: cracking the scale on the hot-rolled steel strip; shot-blasting the cracked scale to remove the scale; deforming the hot-rolled steel strip so as to weaken the bond between scale remaining after the shot-blasting and the hot-rolled steel strip and so as to impart surface roughness to the hot-rolled steel sheet; and polishing the deformed hot-rolled steel strip to remove the remaining scale.

Abstract: Provided is an aluminum coated steel sheet having excellent oxidation and heat resistance. The aluminum coated steel sheet includes an aluminum coating layer and an alloy layer. The aluminum coating layer is formed on a surface of a steel sheet which includes 0.001 to 0.015 wt % of carbon (C), 0.05 to 0.3 wt % of silicon (Si), 0.1 to 0.6 wt % of manganese (Mn), 0.01 to 0.05 wt % niobium (Nb), 0.01 wt % or less of phosphorus (P), 0.01 wt % or less of sulfur (S), 0.1 wt % or less of soluble aluminum (Al), 0.05 to 0.5 wt % of copper (Cu), 0.05 to 0.5 wt % nickel (Ni), 0.001 to 0.01 wt % of nitrogen (N), and the balance of Fe and inevitable impurities. The alloy layer includes an intermetallic compound at an interface between the steel sheet and the aluminum coating layer.

Abstract: Provided is an aluminum coated steel sheet having excellent oxidation and heat resistance. The aluminum coated steel sheet includes an aluminum coating layer and an alloy layer. The aluminum coating layer is formed on a surface of a steel sheet which includes 0.001 to 0.015 wt % of carbon (C), 0.05 to 0.3 wt % of silicon (Si), 0.1 to 0.6 wt % of manganese (Mn), 0.01 to 0.05 wt % niobium (Nb), 0.01 wt % or less of phosphorus (P), 0.01 wt % or less of sulfur (S), 0.1 wt % or less of soluble aluminum (Al), 0.05 to 0.5 wt % of copper (Cu), 0.05 to 0.5 wt % nickel (Ni), 0.001 to 0.01 wt % of nitrogen (N), and the balance of Fe and inevitable impurities. The alloy layer includes an intermetallic compound at an interface between the steel sheet and the aluminum coating layer.

Abstract: Provided is a hot dip zinc (Zn) alloy plated steel sheet having excellent corrosion resistance and surface qualities, and a method of manufacturing the same. For this purpose, the present invention provides a high corrosion resistant hot dip Zn alloy plated steel sheet which includes an underlying steel sheet and a hot dip Zn alloy plating layer, wherein a composition of the hot dip Zn alloy plating layer includes 1 to 3 wt % of aluminum (Al), 1.5 to 4.0 wt % of magnesium (Mg), and Zn and avoidable impurities as a remainder, in which Al+Mg is in a range of 2.5 to 7.0 wt % and Al:(Al+Mg) is in a range of 0.38 to 0.48, and a method of manufacturing the high corrosion resistant hot dip Zn alloy plated steel sheet.

Abstract: Provided is a descaling device for effectively removing scale formed on a surface of a hot-rolled steel strip (steel sheet). The descaling device, for example, may be configured to include: a device housing disposed in a feed path of a hot-rolled steel strip, a high-pressure fluid supply unit provided to supply a high-pressure fluid to the device housing, an abrasive input unit provided to introduce an abrasive to the device housing, and an abrasive slurry spraying unit provided in the device housing to spray an abrasive slurry of the high-pressure fluid and the abrasive mixed inside the device housing on the steel strip.

Abstract: A method for continuously removing scale from a hot-rolled carbon steel strip includes: cracking the scale on the hot-rolled steel strip; shot-blasting the cracked scale to remove the scale; deforming the hot-rolled steel strip so as to weaken the bond between scale remaining after the shot-blasting and the hot-rolled steel strip and so as to impart surface roughness to the hot-rolled steel sheet; and polishing the deformed hot-rolled steel strip to remove the remaining scale.