| 摘要 |
PURPOSE:To change and regulate the cooling rates for steel strips over a wide range and make the production of steel strips having wide latitudes of quality characteristics possible by regulating the temp. of the cooling water in a cooling device of a continuous annealing line and the water level of tanks for cooling suitably. CONSTITUTION:A cold rolled steel strip is subjected to recrystallization heat treatment in the heating and soaking zone 4 of a continuous annealing device, after which it is cooled in water cooling tanks 5, 6, passes through an overaging treatment furnace 8, a final cooling tank 9, a surface conditioning tank 10 and a temper mill 12, and is taken up with a tension reel 13. In this case, a spray device 7 for changing cooling rates is provided in the tank 6, and the depth of immersion of the steel strip in the water tank is made adjustable to 0-5m. The width of spray nozzles of the time when the cooling water temp. is above 60 deg.C and below 60 deg.C is set at 1/4-3/4 in the steel strip and larger than the width of the steel strip, and the head pressure is kept at 0.5/cm<2> and >=0.1kg/cm<2>, whereby the cooling rate is regulated to 50-3,000 deg.C/sec. |
