High-strength flat steel product having a bainitic-martensitic microstructure and method for producing such a flat steel product

US10724113B2 · kind B2 · utility

Assignee

• ThyssenKrupp Steel Europe AG · DE

Inventors

• Andreas Kern · Roth, DE
• Elena Schaffnit · Düsseldorf, DE
• Hans-Joachim Tschersich · Dorsten, DE

Key dates

• Filing date: Feb 3, 2015
• Grant date: Jul 28, 2020
• Expiry date: Feb 13, 2036

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D2211/008
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

The disclosed flat steel products have optimal mechanical properties such as high strength and good toughness, but are also well-suited for welding and other manufacturing processes. The steel products may have a ferrite-free microstructure with at least 95% by volume martensite and bainite, with a martensite content of at least 5% by volume, and no more than 5% by volume residual austenite and unavoidable microstructure constituents from the production process. In addition to iron and unavoidable impurities, a composition of the flat steel products may include in percent by weight: 0.08%-0.10% C, 0.015%-0.50% Si, 1.20%-2.00% Mn, 0.020%-0.040% Al, 0.30%-1.00% Cr, 0.20-0.30% Mo, 0.020-0.030% Nb, 0.0015-0.0025% B, up to 0.025% P, up to 0.010% S, and up to 0.006% N. Impurities can include up to 0.12% Cu, up to 0.090% Ni, up to 0.0030% Ti, up to 0.009% V, up to 0.0090% Co, up to 0.004% Sb, and up to 0.0009% W.