| 摘要 |
PURPOSE:To impart uniform mechanical property to the whole steel plate by a method wherein immediately after hot rolling, thick steel plate of Ni-alloy steel or low alloy steel is quenched to an optimum quenching temperature, the shape of the steel plate is corrected by a leveler, and the quenched steel is tempered. CONSTITUTION:Ni-alloy steel or low alloy steel containing a small amount of Cr, Mo, Ni, V etc. is hot-rolled by a finishing mill 1 into thick steel plate, and the temperature of the steel is detected at the outlet of the mill 1 by a temperature detector 6. Water pressure and water volume are controlled by the detected signal. The steel plate is fed to a cooling controlling equipment 3 which is sprinkled with water. In the equipment 3, the steel plate is quenched to a temperature of from Ar3 transformation temperature to 950 deg.C. The steel plate is fed to a leveler 4 where the shape of the steel plate is corrected, and then fed to a water-cooling equipment 2. The lowering of the temperature of the back end part of the steel plate to a quenching temperature is prevented by the heat insulating cover 5 of the equipment 2. In the water cooling equipment 2, the whole part of the steel plate is uniformly quenched at an optimum quenching temperature. Then conventional tempering treatment is carried out to give uniform mechanical property to the whole steel plate. |
