Apparatus and method for hot rolling

A hot rolling apparatus for rolling a steel to be rolled to manufacture a steel plate with a particle diameter of less than 5 μm, comprising:

• a mill arranged on a preceding stage;
• mills of at least two stands arranged on a later stage, said mills of at least two stands being selected from a list comprising different-diameter roll mills each including a pair of different-diameter work rolls having an equivalent roll diameter of less than 600 mm, one of said pair of different-diameter work rolls being directly driven, and minimum-diameter roll mills each including a pair of work rolls each having a diameter of less than 600 mm;
• cooling units to cool said steel so that a particle growth in a micro-structure of said steel after being rolled can be suppressed, said cooling units being arranged on exit sides of said mills of at least two stands on said later stage, said at least two stands including a last stand on said later stage, one of said cooling units being positioned immediately downstream of the last stand on said later stage;
• and
• a fluid jet spray for jetting a fluid to said steel to be rolled and removing cooling water existing on said steel to be rolled, said fluid jet spray being arranged on a downstream side of said cooling unit in a flow direction of said steel to be rolled on an exit side of said mill of said stand on a last stage, wherein said fluid jet spray includes a plurality of nozzles for blowing out pressurized water toward said steel to be rolled so as to spread in a width direction of said steel to be rolled slantwise downward from above said steel to be rolled toward an upstream side in a flow direction of said steel to be rolled, and wherein said mill of said preceding stage and said mills of said later stage are configured such that a pressurization rate of said mills of said later stage is larger than a pressurization rate of said preceding stage.