Method for manufacturing flat steel products and flat steel product

US11453923B2 · kind B2 · utility

Assignees

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

Inventors

• Frank Friedel · Leuna, DE
• Friedhelm Macherey · Alpen, DE
• Lena Sattler · Krefeld, DE
• Robert Yanik · Paderborn, DE

Key dates

• Filing date: Sep 13, 2017
• Grant date: Sep 27, 2022
• Expiry date: Sep 21, 2039

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D2211/005
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A flat steel product which, following a 5% biaxial deformation, exhibits, on one surface, a Wsa(1-5) value of <0.35 μm, a planar anisotropy Δr of −0.5 to +0.5 and, from the surface to a depth of <200 μm, and a nanohardness of >0.1 to <3.0 GPa. Also, a method of making the product where a slab including (in wt. %) 0.0003-0.050% C, 0.0001-0.20% Si, 0.01-1.5% Mn, 0.001-0.10% P, 0.0005-0.030% S, 0.001-0.12% AI, and 0.0001-0.01% N, the remainder Fe and impurities is heated to 1200-1270° C., rough-rolled with a reduction of 80-90%, and finish-hot-rolled at 850-950° C. with a reduction of 85-95%, for a total deformation of 95-99.5%. The reduction in the last hot roll pass is 1-25%, and the product is cooled at 4-30 K/s to a coiling temperature of 620-780° C. Following pickling, the product is cold-rolled with a total degree of deformation of 70-90% and recrystallization annealed at 650-900° C.