METHOD FOR MANUFACTURING HOT-ROLLED STEEL SHEET MADE OF HIGH-CARBON STEEL OR HIGH-CARBON ALLOY STEEL

PROBLEM TO BE SOLVED: To reduce variations in longitudinal mechanical characteristics such as hardness caused in the case a hot-rolled steel strip made of high-carbon steel is wound up into a coil before the completion of pearlite transformation, by surely performing a predetermined cooling process over an approximately whole area in a longitudinal direction of the steel strip. SOLUTION: The high-carbon steel or high-carbon alloy steel includes 0.50 to 1.50 mass% C. The manufacturing method comprises the steps of: when a temperature in the strip 25 of the above steel or alloy steel is in a range between an outlet temperature of a finish rolling step and a first cooling-stopping temperature determined in a range lower than the outlet temperature but higher than an A1-transformation-starting temperature, water-cooling the approximately whole area in the longitudinal direction of the steel strip 25; when the temperature is in a range between the first cooling-stopping temperature and the A1transformation-starting temperature, air-cooling the approximately whole area in the longitudinal direction of the steel strip 25; further when the temperature is in a range of the A1transformation-starting temperature or lower, water-cooling the approximately whole area in the longitudinal direction of the steel strip 25, to complete pearlite transformation; and winding the steel strip 25 up into the coil at a predetermined winding temperature. COPYRIGHT: (C)2005,JPO&NCIPI