The present invention is provided with: a duct of which one end interconnects to a wiping nozzle (22, 23) and the other end is open; a first valve (17) that controls the actual gas pressure (P1) of the wiping nozzle (22, 23); a second valve (18) that controls the gas flow rate (Q2) dissipating to outside the system from another branched duct; a wiping pressure setting unit (11) that sets the set gas pressure (P1) of the wiping nozzle (22, 23); a first valve aperture setter (13) that sets the valve aperture of the first valve (17); a second valve aperture setter (14) that sets the valve aperture of the second valve (18); and a computation processing unit (12) that presents to the first valve aperture setter (13) the valve aperture at which the gas pressure (P1) matches a set gas pressure (P1), and presents to the second valve aperture setter (14) the valve aperture at which the total gas flow rate (QT) supplied from a gas supply device (15) becomes uniform.

Provided is a method of controlling coating weight coated on a strip by using an air knife disposed in a travelling direction of the strip in a continuous plating process in which the strip is dipped in a molten metal pot and is coated. The method includes: training a neural network with accumulated operation conditions; and deriving an absolute value of at least one of an air knife gap and an air knife pressure by using the trained neural network based on an input operation condition.

A continuous galvanizing line having an annealing furnace of an all radiant tube heating type includes a moisture removal device, dew-point meters, outlets through which the atmospheric gas in the furnace is collected and inlets through which the atmospheric gas from which moisture has been removed with the moisture removal device is fed into the furnace, the dew-point meters and the outlets being placed at least at two points which respectively exist on a side wall in the vicinity of the entrance of the annealing furnace and on a side wall in the vicinity of the furnace top or the furnace bottom at a position where a steel sheet has a maximum end-point temperature, the inlets being placed at two points which respectively exist on side walls on the sides opposite to the sides of the two points for the outlets in the height direction of the furnace, making it possible to steadily control the dew-point of the atmospheric gas to be 45 C. or lower and 80 C. or higher throughout the whole area of the annealing furnace.

The invention provides a vertical annealing furnace including a heating zone and a soaking zone without any partition wall therebetween. The furnace has furnace-to-refiner gas suction openings disposed in a lower portion of a joint between the soaking zone and a cooling zone and in the heating zone and/or the soaking zone except a region extending 6 m in a vertical direction and 3 m in a furnace length direction both from a steel strip inlet at a lower portion of the heating zone. The furnace has refiner-to-furnace gas ejection openings disposed in a region in the joint between the soaking zone and the cooling zone, the region being located above the pass line in the joint, and in a region in the heating zone located above 2 m below the center of upper hearth rolls in the vertical direction.

A method of producing a galvannealed steel sheet includes: annealing a steel strip by conveying the steel strip through a heating zone including a direct fired furnace, a soaking zone, and a cooling zone in this order in an annealing furnace; hot-dip galvanizing the steel strip discharged from the cooling zone; and heat-alloying a galvanized coating formed on the steel strip. Mixed gas of humidified gas and dry gas is supplied into the soaking zone from at least one gas supply port located in a region of lower of the soaking zone in a height direction so that a dew point measured in a region of upper of the soaking zone in the height direction and a dew point measured in a region of lower of the soaking zone in the height direction are both 20 C. or more and 0 C. or less.

The present invention reduces the amount of gas consumed, edge-overcoating and splashing and adjusts plating thickness with high precision by providing a wiping nozzle with: thin plates, which are each inserted into a lip from the entrances to the lip for a specified distance to the inside of the two ends of the lip in the sheet width direction in order to seal the gas jet where the thin plates are inserted, and which are movable in the sheet width direction of the lip; and ropes extending in the sheet width direction of the lip so as to track the movements of the thin plates and seal the gas jet in a specified range.

A plated steel sheet with a quasicrystal includes a steel sheet and a plated-metal-layer arranged on a surface of the steel sheet. The plated-metal-layer includes, as a chemical composition, Mg, Zn. The plated-metal-layer includes, as a metallographic structure, a quasicrystal phase. A Mg content, a Zn content, and an Al content in the quasicrystal phase satisfy 0.5Mg/(Zn+Al)0.83 in atomic %. In addition, an average equivalent circle diameter of the quasicrystal phase is equal to or larger than 0.01 m and equal to or smaller than 1 m.

A steel sheet shape control method includes, (A) setting a target correction shape of the steel sheet at a position of an electromagnet to a curved shape, (B) measuring a steel sheet shape when electromagnetic correction is performed, (C) calculating the steel sheet shape in a nozzle position based on the steel sheet shape, (D) repeating (B) and (C) by resetting the target correction shape to a curved shape having a smaller amount of warp, (E) when the amount of warp of the steel sheet shape at the position of the nozzle is less than the upper limit value, (F) calculating vibration of the steel sheet at the position of the nozzle, and (G) adjusting a control gain of the electromagnet until amplitude of vibration is less than a second upper limit value when the amplitude of the vibration is equal to or more than the second upper limit value.

The invention relates to a method for patinating zinc surfaces of a structural element, including the steps of: providing a structural element with a zinc surface in a housing; providing an atmosphere around the zinc surface, wherein said atmosphere comprises carbon based gas and humidity; and heating the zinc surface for at least one hour, to provide a patinated zinc surface. The heating of the zinc surface occurs by heating the atmosphere to a temperature of at least 50 C., the humidity is at least 70%, and the carbon-based gas concentration is at least 5% by volume. The invention also relates to a patinated evaporative condenser in a closed-circuit cooling tower The patinated evaporative condenser in a closed-circuit cooling tower is by the method according to the invention. A system for patinating zinc surfaces according to the invention is also disclosed.

A steel sheet shape control method includes, (A) setting a target correction shape of the steel sheet at a position of an electromagnet to a curved shape, (B) measuring a steel sheet shape when electromagnetic correction is performed, (C) calculating the steel sheet shape in a nozzle position based on the steel sheet shape, (D) repeating (B) and (C) by resetting the target correction shape to a curved shape having a smaller amount of warp, (E) when the amount of warp of the steel sheet shape at the position of the nozzle is less than the upper limit value, (F) calculating vibration of the steel sheet at the position of the nozzle, and (G) adjusting a control gain of the electromagnet until amplitude of vibration is less than a second upper limit value when the amplitude of the vibration is equal to or more than the second upper limit value.