Patent ID: 8359894

Claim:
A method for cooling a hot-rolled steel strip after a finishing rolling in which a transportation speed varies, the method including: setting a transportation-speed changing schedule based on a temperature of a steel strip before the finishing rolling and a condition of the finishing rolling; performing a first cooling in which the hot-rolled steel strip is cooled under a film boiling state in a first cooling section; performing a second cooling in which the hot-rolled steel strip is cooled with a water amount density of not less than 2 m 3 /min/m 2 in a second cooling section; and coiling the hot-rolled steel strip, wherein a cooling condition is controlled in the first cooling such that a target temperature T 2 a of the steel strip on an input side in the second cooling section before a change in a speed of rolling, a target temperature T 2 a ′ of the steel strip on an input side in the second cooling section after a change in the speed of rolling, and a change amount ΔTx of an amount of cooling the hot-rolled steel strip in the second cooling section, the change amount being caused by the change in the speed of rolling, satisfy 0.8≦( T 2 a′−T 2 a )/Δ Tx≦ 1.2 (Equation 1).