HIGH-STRENGTH STEEL SHEET HAVING EXCELLENT DUCTILITY AND LOW-TEMPERATURE TOUGHNESS, AND METHOD FOR PRODUCING SAME

A high-strength steel sheet of the present invention is a steel sheet satisfying a predetermined component composition. A metal structure of the steel sheet is composed of polygonal ferrite, high-temperature region generated bainite, low-temperature region generated bainite and retained austenite ea...

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Bibliographische Detailangaben
Hauptverfasser:	MURATA TADAO, MIZUTA SAE, FUTAMURA YUICHI, KASUYA KOJI
Format:	Patent
Sprache:	eng
Schlagworte:	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
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Beschreibung
Zusammenfassung:	A high-strength steel sheet of the present invention is a steel sheet satisfying a predetermined component composition. A metal structure of the steel sheet is composed of polygonal ferrite, high-temperature region generated bainite, low-temperature region generated bainite and retained austenite each having a predetermined area percent, and a distribution using each average IQ of predetermined crystal grains determined by electron backscatter diffraction satisfies Equations (1) and (2) below. According to the present invention, a high-strength steel sheet having excellent ductility and low-temperature toughness can be realized even at a tensile strength of 780 MPa or more. (IQave−IQmin)/(IQmax−IQmin) 0.40 (1) ( IQ)/(IQmax−IQmin) 0.25 (2)