STEEL SHEET, MEMBER, AND METHOD FOR MANUFACTURING STEEL SHEET AND MEMBER
Provided are a steel sheet having high strength, high ductility, excellent stretch flange formability, and good chemical convertibility; a related member; and methods for manufacturing them.The steel sheet has a chemical composition including specific amounts of C, Si, Mn, P, S, sol. Al, and N in ma...
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Format: | Patent |
Sprache: | eng ; fre ; ger |
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Zusammenfassung: | Provided are a steel sheet having high strength, high ductility, excellent stretch flange formability, and good chemical convertibility; a related member; and methods for manufacturing them.The steel sheet has a chemical composition including specific amounts of C, Si, Mn, P, S, sol. Al, and N in mass%. The steel sheet has a specific ratio of the total of polygonal ferrite, upper bainite, retained γ, fresh martensite, tempered martensite, and lower bainite, and a specific ratio of a remaining microstructure. The steel sheet has a specific ratio of the number of fresh martensite grains and retained γ grains having an equivalent circular diameter of less than 1.2 um, and has a specific ratio of the number of fresh martensite grains and retained γ grains having an aspect ratio of 2.5 or more and an equivalent circular diameter of 1.2 um or more. |
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