Abstract: Provided is a hot-dip Al—Zn—Mg—Si coated steel sheet having good corrosion resistance in flat parts and edge parts, and also having excellent worked part corrosion resistance. The hot-dip Al—Zn—Mg—Si coated steel sheet includes a base steel sheet and a hot-dip coating on a surface of the base steel sheet. The hot-dip coating includes an interfacial alloy layer present at an interface with the base steel sheet and a main layer present on the interfacial alloy layer, and contains from 25 mass % to 80 mass % of Al, from greater than 0.6 mass % to 15 mass % of Si, and from greater than 0.1 mass % to 25 mass % of Mg. The Mg content and Si content in the hot-dip coating satisfy formula (1): MMg/(MSi?0.6)>1.7??(1) where MMg represents the Mg content (mass %) and MSi represents the Si content (mass %).

Abstract: Provided is a hot-dip Al—Zn—Mg—Si coated steel sheet having good corrosion resistance in flat parts and edge parts, and also having excellent worked part corrosion resistance. The hot-dip Al—Zn—Mg—Si coated steel sheet includes a base steel sheet and a hot-dip coating on a surface of the base steel sheet. The hot-dip coating includes an interfacial alloy layer present at an interface with the base steel sheet and a main layer present on the interfacial alloy layer, and contains from 25 mass % to 80 mass % of Al, from greater than 0.6 mass % to 15 mass % of Si, and from greater than 0.1 mass % to 25 mass % of Mg. The Mg content and Si content in the hot-dip coating satisfy formula (1): MMg/(MSi?0.6)>1.7 ??(1) where MMg represents the Mg content (mass %) and MSi represents the Si content (mass %).

Abstract: A hot-dip Al—Zn alloy coated steel sheet having good corrosion resistance in flat parts as well as good workability and thereby has excellent corrosion resistance in worked parts. The upper layer of the hot-dip coating has a composition containing Al in an amount of 20 mass % to 95 mass %, Si in an amount of 10% or less of the Al content, at least one of Ca and Mg, the total content of Ca and Mg being 0.01 mass % to 10 mass %, and the balance including Zn and incidental impurities, and the mean Vickers hardness of the hot-dip coating is 50 Hv to 100 Hv.

Abstract: A high tensile-strength galvanized steel sheet includes C: at least 0.05% but less than 0.12%, Si: at least 0.01% but less than 0.35%, Mn: 2.0% to 3.5%, P: 0.001% to 0.020%, S: 0.0001% to 0.0030%, Al: 0.005% to 0.1%, N: 0.0001% to 0.0060%, Cr: more than 0.5% but not more than 2.0%, Mo: 0.01% to 0.50%, Ti: 0.010% to 0.080%, Nb: 0.010% to 0.080%, and B: 0.0001% to 0.0030%, the remainder being Fe and unavoidable impurities, wherein the high tensile-strength galvanized steel sheet has a microstructure that contains 20% to 70% by volume ferrite having an average grain size of 5 ?m or less. The high tensile-strength galvanized steel sheet has a tensile strength of at least 980 MPa, and excellent formability and weldability.

Abstract: A hot dip Al—Zn coated steel sheet exhibits excellent corrosion resistance. The Al content in a coated film is 20-95% by mass. The Ca content is 0.01-10% by mass. Alternatively, the total content of Ca and Mg is 0.01-10% by mass. Preferably, the coated film includes an upper layer and an alloy phase present at the interface to a substrate steel sheet, and Ca or Ca and Mg are contained primarily in the upper layer. Also preferably, the Ca or Ca and Mg include an intermetallic compound with at least one type selected from Zn, Al, and Si. If Ca or Ca and Mg are contained in the coated film, as described above, these elements are contained in corrosion products generated in a bonded portion and exert effects of stabilizing the corrosion products and retarding proceeding of corrosion thereafter. Then, as a result, the corrosion resistance is improved.

Abstract: A high tensile-strength galvanized steel sheet includes C: at least 0.05% but less than 0.12%, Si: at least 0.01% but less than 0.35%, Mn: 2.0% to 3.5%, P: 0.001% to 0.020%, S: 0.0001% to 0.0030%, Al: 0.005% to 0.1%, N: 0.0001% to 0.0060%, Cr: more than 0.5% but not more than 2.0%, Mo: 0.01% to 0.50%, Ti: 0.010% to 0.080%, Nb: 0.010% to 0.080%, and B: 0.0001% to 0.0030%, the remainder being Fe and unavoidable impurities, wherein the high tensile-strength galvanized steel sheet has a microstructure that contains 20% to 70% by volume ferrite having an average grain size of 5 ?m or less. The high tensile-strength galvanized steel sheet has a tensile strength of at least 980 MPa, and excellent formability and weldability.

Abstract: The method for manufacturing coated steel sheet has the steps of: immersing a steel sheet in a hot-dip coating bath to form an Al—Zn base coating layer containing 20 to 95 mass % Al on the steel sheet, forming a passivated layer on the coating layer; and applying thermal history to the coating layer. The thermal history is applied immediately after the steel sheet left the hot-dip coating bath or in a temperature range of from T(° C.) between 130° C. and 300° C. to 100° C.

Abstract: An apparatus for hot-dip coating a steel strip, comprising: (a) an annealing furnace for continuously annealing the steel strip, the annealing furnace having an entrance side and an exit side; (b) a coating pot having a molten metal coating bath for coating the annealed steel strip; (c) a snout through which the annealed steel strip is introduced into the molten metal coating bath, one end of the snout being connected to the annealing furnace and the other end being immersed into the molten metal coating bath; (d) a seal device for sealing between the annealing furnace and the snout, the seal device being disposed at the exit side of the annealing furnace; and (e) a discharge device for discharging a gas containing a metal vapor from the snout to outside of the snout, the metal vapor being evaporated from the molten metal coating bath in the snout.

Abstract: A method for hot-dip coating a steel strip comprises: (a) continuously annealing the steel strip in an annealing furnace; (b) introducing the annealed steel strip into a molten metal coating bath through a snout; (c) dipping the annealed steel strip into the molten metal coating bath; (d) controlling a pressure inside of the snout; and (e) discharging a gas containing a metal vapor from the snout to outside of the snout. An apparatus comprises an annealing furnace, a coating pot, a control device for controlling a pressure inside the snout and a gas discharging device.