HIGH-STRENGTH STEEL SHEET AND METHOD FOR PRODUCING SAME

• Main Authors: KOJIMA Katsumi, KARIYA Nobusuke, SHIIMORI Fusae, SAITO Hayato
• Format: Patent
• Language: English
• Published: 22.03.2021
• 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 high-strength steel sheet having excellent ductility and bendability, and a tensile strength of at least 500 MPa, specifically a high-strength thin steel sheet which is for cans and has a sheet thickness in the range of 0.1-0.8 mm. This high-strength steel sheet has a composition containing 0.03-0.15 pcnt of C, 0.01-0.05 pcnt of Si, more than 0.6 pcnt and at most 1.5 pcnt of Mn, at most 0.025 pcnt of P, at most 0.02 pcnt of S, 0.01-0.10 pcnt of Al, 0.0005-0.0100 pcnt of N, 0.005-0.020 pcnt of Ti, 0.0005-0.0100 pcnt of B, and 0.0050-0.0200 pcnt of Nb, with the remainder comprising iron and inevitable impurities, and has a metallic structure containing at least 85 pcnt of ferrite and 1-10 pcnt of martensite in area ratio, wherein the martensite grain size is 5 æm or less and the percentage of martensite grains having a grain size of 2 æm or less is at least 80 pcnt .