STEEL SHEET FOR CROWN CAPS, PRODUCTION METHOD THEREFOR, AND CROWN CAP

• Main Authors: UMEMOTO, MASASHI, TSUJIMOTO, MASAMI, KOJIMA, KATSUMI, HIRAGUCHI, TOMONARI, KARIYA, NOBUSUKE
• Format: Patent
• Language: English; Polish
• Published: 19.07.2021
• Subjects: ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; ALLOYS; CHEMISTRY; CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS,e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES,DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; CONVEYING; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; HANDLING THIN OR FILAMENTARY MATERIAL; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PACKAGES; PACKAGING ELEMENTS; PACKING; PERFORMING OPERATIONS; STORING; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

To provide a steel sheet for crown caps, having sufficient pressure resistance and formability regardless of gauge reduction; a method for manufacturing the same; and a crown cap. A steel sheet for crown caps has a predetermined composition, wherein N total-(N as AlN) is 0.0090% to 0.0170%, the maximum grain size of a carbide is 2.0 µm or less in a cross section in a rolling direction, and the yield strength is 420 MPa to 600 MPa in the rolling direction. A method for manufacturing a steel sheet for crown caps includes a hot rolling step of coiling a steel material having a predetermined composition at a predetermined temperature after finish rolling; a primary cold rolling step; a continuous annealing step of performing heating at an average heating rate of 10 °C/s to 30 °C/s in a temperature range A from 500 °C to 600 °C in a heating course, annealing at a annealing temperature B in a temperature range from 620 °C to 740 °C, cooling from the annealing temperature B to a cooling stop temperature C in a temperature range from 400 °C to 580 °C at an average cooling rate of 20 °C/s or more, and retaining in the temperature range from 400 °C to 580 °C for a retention time of 30 seconds to 90 seconds after cooling at the above average cooling rate is stopped; and a secondary cold rolling step of performing cold rolling at a rolling reduction ratio of 1.0% to 12%.