A quenching apparatus and a quenching method for a metal sheet with which it is possible to inhibit shape defects from occurring in the metal sheet when quenching is performed and a method for manufacturing a steel sheet. The quenching apparatus is placed on an exit side of a soaking zone in a continuous annealing furnace, and the apparatus includes a cooling fluid-spray device having plural spray nozzles for spraying mist onto both surfaces of a continuously transported metal sheet, and at least one pair of restraining rolls for restraining the metal sheet on both surfaces thereof in a region from a cooling start point to a cooling finish point in the cooling fluid-spray device.

Disclosed is a method for continuous thermal treatment of a steel strip. The strip passes through consecutive thermal treatment chambers, is quickly cooled in at least one of the chambers by spraying liquid onto the strip, or by spraying a fluid made up of gas and liquid or spraying a combination of gas and liquid forming a mist. After quick cooling, a protective metal layer is deposited on the strip by dip coating. The cooling fluid strips iron oxides or other alloy elements contained in the steel to be treated, minimizing oxidation and reducing the oxides on the strip. Spray pressure and distance are chosen to facilitate the stripping property and the mechanical action of the sprayed fluid, reducing the layer of oxides on the strip. The temperature of the strip at the end of the cooling step is the temperature necessary for carrying out the desired treatment cycle.

A quenching apparatus for a metal sheet, continuous annealing equipment, a method for quenching a metal sheet, a method for manufacturing a cold rolled steel sheet, and a method for manufacturing a coated steel sheet. The quenching apparatus has a water tank in which the metal sheet is passed and immersed in a liquid to cool the metal sheet, a water injection apparatus placed in the water tank, and plural restraining roll pairs with which the metal sheet that is passed in the water tank is restrained. The water injection apparatus has plural water injection nozzles arranged in a sheet passing direction of the metal sheet on front and back surface sides of the metal sheet. A position of each of the plural restraining roll pairs is separately adjusted with respect to the metal sheet in accordance with operation conditions.

A rapidly quenched Fe-based soft-magnetic alloy ribbon having wave-like undulations on a free surface, the wave-like undulations having transverse troughs arranged at substantially constant intervals in a longitudinal direction, and the troughs having an average amplitude D of 20 mm or less, is produced by a method comprising (a) keeping a transverse temperature distribution in a melt nozzle within 15 C. to have as small a temperature distribution as possible in a melt paddle of the alloy, and (b) forming numerous fine linear scratches on a cooling roll surface by a wire brush, thereby providing a ground surface of the cooling roll with an arithmetical mean (average) roughness Ra of 0.1-1 m and a maximum roughness depth Rmax of 0.5-10 m.

A metal-strip rapid cooling apparatus includes a cooling fluid ejection device including one set of nozzles or a plurality of sets of nozzles arranged in a horizontal direction, and configured to eject a cooling fluid onto the metal strip from both sides of the metal strip; cooling fluid removing rolls configured to remove a remaining fluid from the metal strip onto which the cooling fluid has been ejected; and movable masking plates on both sides of a metal strip pass line along which the metal strip passes, the movable masking plates each disposed between the metal strip pass line and the nozzles, and configured to move in the horizontal direction to adjust a cooling start position and control a distance from the cooling start position to the cooling fluid removing rolls, the cooling start position positioned such that the metal strip starts to be cooled with the cooling fluid.

Provided is an annealing facility that contributes to further improvement of magnetic properties by more active control of carbon in steel. An annealing facility includes a heating zone, a soaking zone, and a cooling zone on a conveyance line for a steel strip. The conveyance line is capable of passing a steel strip with a thickness of 2.8 mm or more, the soaking zone has means for maintaining an ambient temperature at 900 C. or higher, the cooling zone has means for supplying a refrigerant to the steel strip and maintaining an average cooling rate of 50 C./s or higher in a temperature region of 750 C. or lower and 120 C. or higher, and the annealing facility includes removal means for removing the refrigerant on an exit side of the cooling zone.

A metal-strip warped-shape control method for controlling an exit-side warped shape, which is a warped shape of a metal strip downstream of a temper rolling mill in a metal-strip manufacturing facility, the metal-strip manufacturing facility including the temper rolling mill that corrects a shape of the metal strip continuously conveyed, and a warped-shape measurement device that measures a warped shape of the metal strip, the metal-strip warped-shape control method including: calculating an approximation curve for the warped shape of the metal strip using an approximation method selected from parabolic approximation, circular arc approximation, and envelope approximation; and setting operating parameters of the temper rolling mill that can reduce a warp height of the exit-side warped shape based on the approximation curve that is calculated.

A metal-strip warped-shape prediction method for predicting an exit-side warped shape, which is a warped shape of a metal strip downstream of a temper rolling mill in a metal-strip continuous annealing facility, the metal-strip continuous annealing facility including: heating equipment that heats the metal strip, cooling equipment that cools the metal strip heated by the heating equipment, the temper rolling mill that corrects a shape of the metal strip cooled by the cooling equipment, and an entry-side warped-shape measurement device that measures an entry-side warped shape, which is a warped shape of the metal strip upstream of the temper rolling mill between the cooling equipment and the temper rolling mill, the metal-strip warped-shape prediction method including: predicting the exit-side warped shape based on the entry-side warped shape and at least one of operating parameters of the temper rolling mill.