PRODUCTION OF HOT ROLLED STEEL SHEET HAVING EXCELLENT MATERIAL QUALITY UNIFORMITY AND SHAPE CHARACTERISTIC IN TRANSVERSE DIRECTION

摘要

PURPOSE:To produce a hot rolled steel sheet having excellent uniformity and shape in the transverse direction by controlling cooling water with the measured value obtd. by transformation rate meters provided in the central part in the transverse direction and end part of the hot rolled steel sheet passing through a cooler in the stage of producing the hot rolled steel sheet. CONSTITUTION:The steel sheet emitted from the final stand 1 is passed with a thickness gage 4 and a finishing thermometer 5 and is cooled with water in a cooler 7 and after the coiling temp. thereof is measured with a coiling thermometer 6, the steel sheet is coiled on a coiler 2 in the hot rolling stage of the steel sheet. The gamma alphatransformation rates are measured with the transformation rate meters 9 at the central part and end part of the steel sheet emitted from the cooler 7. Shielding plates 8 for the cooling water provided to the cooler 7 are actuated as shown by arrows according to the measured values to adjust the flow rate of the cooling water in the central part and end part of the steel sheet, by which the cooling condition is controlled. The transformation of gamma alpha of the steel sheet is uniformly executed in the transverse direction, by which the hot rolled steel sheet having the excellent uniformity and shape in the transverse direction is produced.