| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for cooling a hot-rolled steel sheet, capable of avoiding a trouble leading to production stoppage, even when a strong cooling with enhanced cooling rate and cooling quantity, which is needed for manufacturing of ultrafine grain steel, is performed, while improving the yield by suppressing tension fluctuations between a final mill and a pinch roll.SOLUTION: In a method for cooling a hot-rolled steel sheet, when the hot-rolled steel sheet is manufactured using a manufacturing apparatus including: a cooling device which is installed just after a final mill of a finishing mill string and provided with a plurality nozzles within a fixed section in a rolling direction; and a pinch roll which is installed on the outlet side of the cooling device and abuts on both upper and lower surfaces of the hot-rolled steel sheet, cooling by the cooling device is started at a predetermined time after a tip of the hot-rolled steel sheet reaches the pinch roll to establish the tension of the hot-rolled steel sheet between the final mill of the finishing mill string and the pinch roll. At that time, the time until the cooling liquid flow rate of each nozzle reaches a predetermined value after starting the cooling is set to be longer in the nozzles located closer to the pinch roll. |
