METHOD FOR MANUFACTURING HOT-ROLLED STEEL SHEET

• Main Authors: KUBOYAMA EIICHI, HAYASHIDA TERUKI, ARISUMI SEIJI, KARASHIMA HIROSUKE, ABE HIROSHI
• Format: Patent
• Language: English
• Published: 25.10.2007
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; PUNCHING METAL; ROLLING OF METAL; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PROBLEM TO BE SOLVED: To provide a method for manufacturing a hot rolled steel sheet by which a surface shape can be made excellent by suppressing the occurrence of scale defects at the time of hot rolling. SOLUTION: A slab manufactured by continuous casting etc., is heated in a heating furnace and is subjected to rough rolling by a rougher 1, and thereafter, high pressure water 6 is injected from a nozzle 5 of a descaling apparatus to remove the scale formed on the surface. Thereafter, the steel sheet is immediately hot rolled by a finishing mill 3 equipped with rolling stands 2a to 2g. At this time, the nozzle 10 is arranged right behind the first stand 2a, and the water 11 is made to flow out of the nozzle under the conditions of water pressure <7.8 MPa and an amount of water 200 to 1,500 liter/m2x minute or the gas of ≤0.1vol.% in oxygen content is made to flow out of the nozzle under the conditions of gaseous pressure <5 MPa and a flow rate of 100 to 1,500 liter/m2x minute to cover the surface of the steel sheet ejected from the first stand 2a with the gas of ≤0.1vol.% in the water or oxygen content. COPYRIGHT: (C)2008,JPO&INPIT