Flat steel product and method for producing same

US11597986B2 · kind B2 · utility

Assignees

• ThyssenKrupp Steel Europe AG · DE
• thyssenkrupp AG · DE

Inventors

• Manuela Irnich · Rheinberg, DE
• Rainer Fechte-Heinen · Bottrop, DE
• Miriam Lange · Bochum, DE
• Bernd Linke · Duisburg, DE
• Jan-Hendrik Rudolph · Essen, DE
• Richard G. Thiessen · Malden, NL

Key dates

• Filing date: Jun 12, 2019
• Grant date: Mar 7, 2023
• Expiry date: Sep 7, 2039

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C23C2/06
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

The present invention relates to a flat steel product which has good deep-drawing ability, low edge-crack sensitivity and good bending behaviour. To this end, the flat steel product contains a steel which consists of (in wt %) 0.1-0.5% C, 1.0-3.0% Mn, 0.9-1.5% Si, up to 1.5% Al, up to 0.008% N, up to 0.020% P, up to 0.005% S, 0.01-1% Cr and optionally one or more of the following elements: up to 0.2% Mo, up to 0.01% B, up to 0.5% Cu, up to 0.5% Ni and optionally a total of 0.005-0.2% microalloying elements, the remainder being iron and unavoidable impurities, wherein 75<(Mn2+55*Cr)/Cr<3000 where Mn is the Mn content of the steel in wt % and Cr is the Cr content of the steel in wt %. The steel has a structure which consists of at least 80 area % martensite, of which at least 75 area % is tempered martensite and at most 25 area % is non-tempered martensite, at least 5 volume % residual austenite, 0.5 to 10 area % ferrite and at most 5 area % bainite, wherein in the region of the phase boundary between tempered martensite and residual austenite there is a low-Mn ferrite seam which has a width of at least 4 nm and at most 12 nm and the Mn content of which is at most 50% of the average …