The present invention relates to an ultra-high strength, hot-dip galvanized steel sheet having excellent surface quality and coating adherence and to a method for manufacturing thereof, the ultra-high strength, hot-dip galvanized steel sheet comprising: 0.1-0.3% by weight carbon (C); 0.1-2.0% by weight silicon (Si); 0.005-1.5% by weight aluminum (Al); 1.5-3.5% by weight manganese (Mn); 0.04% by weight or less phosphorus (P) (excluding 0% by weight); 0.015% by weight or less sulphur (S) (excluding 0% by weight); 0.02% by weight or less nitrogen (N) (excluding 0% by weight); the balance being Fe; and other inevitable impurities, and further comprising 0.01 wt.% to 0.07 wt.% of at least one kind of element selected from the group consisting of bismuth (Bi), tin (Sn) and antimony (Sb).

Method for the preoxidation of high-strength strip steel. The invention relates to an improved method for the preoxidation of high-strength strip steel in a reaction chamber arranged in a furnace chamber. The reaction chamber is sealed at a strip entrance and a strip exit against gas exchange between the furnace chamber and the reaction chamber, and a gas that forms an oxidizing atmosphere in the reaction chamber is introduced, and the gas is continuously circulated within the reaction chamber

A high strength galvanized steel sheet has a composition including, C: 0.02% or more and 0.30% or less, Si: 0.01% or more and 2.5% or less, Mn: 0.1% or more and 3.0% or less, P: 0.003% or more and 0.08% or less, S: 0.01% or less, Al: 0.001% or more and 0.20% or less, Ti: 0.03% or more and 0.40% or less and the balance being Fe and inevitable impurities, and a zinc-coated layer having a coating weight per surface of 20 g/m.sup.2 or more and 120 g/m.sup.2 or less. The concentration ratio of C to Ti (C/Ti) in a portion within 10 μm from the surface of the base steel sheet is 0.8 or more and 1.5 or less, and the total amount of oxides of one or more selected from Fe, Si, Mn, P, Al and Ti formed in a surface portion within 100 μm from the surface of the base steel sheet is 0.05 g/m.sup.2 or less.

A method for producing a silicon steel normalizing substrate comprises steelmaking, hot rolling and normalizing steps. A normalizing furnace is used in the normalizing step, and along a moving direction of strip steel, the normalizing furnace sequentially comprises: a preheating section, a nonoxidizing heating section, a furnace throat, furnace sections for subsequent normalizing processing, and a delivery seal chamber. Furnace pressures of the normalizing furnace are distributed as follows: the furnace pressure of a downstream furnace section adjacent to the furnace throat along the moving direction of the strip steel is the highest, the furnace pressure decreases gradually from the furnace section with the highest furnace pressure to a furnace section in an inlet direction of the normalizing furnace, and the furnace pressure decreases gradually from the furnace section with the highest furnace pressure to a furnace section in an outlet direction of the normalizing furnace.

An annealing line for a steel strip, a device for use in such an annealing line and a method for annealing a steel strip. The annealing line including a connecting chamber connecting a first heating section and a second heating section, wherein one or more devices, located in the connecting chamber, are arranged on one or both sides of the steel strip for oxidising the steel strip using an oxidising gas mixture, each device having a body including an internal chamber and one or more openings to project the oxidising gas mixture onto the surface of the steel strip.

A high-strength galvanized steel sheet is excellent in the external appearance of plating and the hydrogen brittleness resistance, and has a high yield ratio, and a method for manufacturing the same. The high-strength galvanized steel sheet including a steel sheet having a specific component composition and a specific steel structure, the amount of diffusible hydrogen in the steel sheet being 0.20 mass ppm or less; and a galvanizing layer provided on a surface of the steel sheet, the galvanizing layer having a content amount of Fe of 8 to 15% in mass %, and an attachment amount of plating per one surface of 20 to 120 g/m.sup.2, wherein the amount of Mn oxides contained in the galvanizing layer is 0.050 g/m.sup.2 or less; and the high-strength galvanized steel sheet has a yield strength of 700 MPa or more and a yield strength ratio of 65% or more and less than 85%.

Cooling device (1) for cooling a wire (100), comprising a first chamber (2) and a second cooling chamber (4) through which the wire (100) passes. The device also comprises cooling liquid driving means (16) for driving the cooling liquid from the first chamber (2) to the second chamber (4) through at least one coding liquid inlet (12). Through the driving means (16) and the cooling liquid inlet (12), a jet of coding liquid is projected on the wire path at a mean speed of at least 0.6 m/s, and at a distance between 6 and 13 times the diameter of the wire (100). Cooling is performed in an inert gas atmosphere inside the second chamber (4). The invention also relates to a corresponding installation and a corresponding wire cooling method.

A method for controlling furnace pressure of a continuous annealing furnace is disclosed. The method comprises detecting a coal gas flow volume and an air flow volume in each section by use of a coal gas flow volume detector and an air flow volume detector disposed in each section of a continuous annealing furnace, respectively, adding up the coal gas flow volume detected in each section to obtain a total input coal gas flow volume; adding up the air flow volume detected in each section to obtain a total input air flow volume, and calculating a pre-combustion gas pressure in the furnace based on the total input coal gas flow volume and the total input air flow volume; detecting compositions of the coal gas and a ratio of the coal gas to the air by use of a composition detector; detecting a pre-combustion gas temperature in the furnace by use of a thermocouple; predicting post-combustion gas compositions and a total gas volume based on chemical combustion reaction equations and based on the total input coal gas flow volume, the total input air flow volume, the coal gas compositions and the ratio of the coal gas to the air; igniting the coal gas and the air in the furnace; and detecting a post-combustion gas temperature in the furnace by use of a thermocouple; calculating a post-combustion gas pressure in the furnace based on the pre-combustion gas pressure in the furnace, pre-combustion gas temperature in the furnace and the post-combustion gas temperature in the furnace; and calculating an opening degree for an exhaust gas fan based on the pre-combustion gas pressure in the furnace and the post-combustion gas pressure in the furnace and by use of a gas increment pass algorithm, and using the opening degree to control the exhaust gas fan.

A galvannealed steel sheet includes: a steel sheet; a coating layer on a surface of the steel sheet; and a mixed layer formed between the steel sheet and the coating layer, in which the mixed layer includes a base iron portion having fine grains having a size of greater than 0 μm and equal to or smaller than 2 μm, a Zn—Fe alloy phase, and oxides containing one or more types of Mn, Si, Al, and Cr, and in the mixed layer, the oxides and the Zn—Fe alloy phase are present in grain boundaries that form the fine grains and the Zn—Fe alloy phase is tangled with the base iron portion.
[Mn]+[Si]+[Al]+[Cr]≧0.4  (Expression 1)

A continuous annealing furnace for annealing steel strips that is a vertical-type annealing furnace is configured so that part of gas inside the furnace is drawn and introduced to a refiner disposed outside the furnace including an oxygen removing apparatus and a dehumidifying apparatus, oxygen and moisture contained in the gas are removed to lower the dew point of the gas, and the gas having a lowered dew point is put back into the furnace. At least one gas inlet through which gas is drawn from the furnace into the refiner is disposed in the vicinity of the entry side of the furnace at a distance of 6 m or less in the vertical direction and 3 m or less in the furnace-length direction from the steel-strip-introduction section located at the lower part of the heating zone.