Metal-strip rapid cooling apparatus, metal-strip rapid cooling method, and method of producing metal strip product

A metal-strip rapid cooling apparatus configured to cool a metal strip while conveying the metal strip in a horizontal direction, the metal-strip rapid cooling apparatus comprising:

• a cooling fluid ejection device including one set of nozzles or a plurality of sets of nozzles arranged in the horizontal direction, the nozzles 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 disposed 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, the movable masking plates 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 being a position at which the metal strip starts to be cooled with the cooling fluid.