STEEL SHEET FOR CROWN CAP, CROWN CAP, AND METHOD FOR PRODUCING STEEL SHEET FOR CROWN CAP

• Main Authors: TATENO Bungo, UENO Takashi, KOJIMA Katsumi, KARIYA Nobusuke, YAMAMOTO Yoshihide
• Format: Patent
• Language: English; French; German
• Published: 20.01.2021
• 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; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

Provided is a steel sheet for crown cap which has excellent formability and from which a crown cap having a sufficient pressure resistance applicable to beverages having a high carbon dioxide content can be produced with the use of a soft liner even when the steel sheet is subjected to sheet metal thinning, the steel sheet for crown cap having: a chemical composition containing, in mass%, C: more than 0.0060 % and 0.0100 % or less, Si: 0.05 % or less, Mn: 0.05 % or more and 0.60 % or less, P: 0.050 % or less, S: 0.050 % or less, Al: 0.020 % or more and 0.050 % or less, and N: 0.0070 % or more and 0.0140 % or less, with the balance being Fe and inevitable impurities; a ferrite phase in a region from a depth of 1/4 of a sheet thickness to a mid-thickness part, the ferrite phase having a standard deviation of ferrite grain size of 7.0 µm or less; a yield strength of 560 MPa or more and 700 MPa or less in a rolling direction; and a difference of 25 MPa or more between a yield strength in a 2 % strain tensile test and a yield strength in a tensile test after heat treatment at 170 °C for 20 minutes, in the rolling direction.