| 摘要 |
PURPOSE: A plate accelerated cooling method for preventing overcooling of the head part of plate using opening/closing time of shut off valves during accelerated cooling, thereby minimizing temperature deviation at the head part of the plate is provided. CONSTITUTION: In a plate accelerated cooling method comprising the processes of performing hot rolling on the steel slab in the hot finish rolling temperature range of 700 to 850 deg.C by heating a steel slab to a temperature of 1,120 to 1,260 deg.C, and accelerated cooling the hot rolled steel slab by controlling flux of the head part of the hot rolled steel slab under the conditions that cooling initiation temperature is from 700 to 820 deg.C, cooling finishing temperature is from 500 to 620 deg.C, and cooling speed is from 3.0 to 12.0 deg.C/sec, the accelerated cooling method for minimizing temperature deviation at the head part of plate comprises the steps of obtaining temperature deviation (ΔT) by measuring temperature (T0) at the central part of hot rolled plate right after cooling and temperature values (T1,T2,T3) at an area from the head part to a point that is 1,000 mm distanced from the head part of the plate; obtaining the number of shut off valves (Vn) using the obtained temperature deviation (ΔT), and obtaining flux control distance (DL) of the head part of the plate; calculating opening/closing time of the shut off valves by accurately applying the obtained number of shut off valves (Vn) and flux control distance (DL) to the head part of the plate; and accelerated cooling the hot rolled plate by applying the obtained flux control conditions of the head part of the plate, that is, the application number of the shut off valves (Qn), overcooling compensation region (DL) and extended time (XL) for partial overcooling prevention.
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