Method for producing a hot strip of a bainitic multi-phase steel having a Zn—Mg—Al coating, and a corresponding hot strip

US11512364B2 · kind B2 · utility

Assignee

• Salzgitter Flachstahl GmbH · DE

Inventors

• Ingwer Denks · Duisburg, DE
• Christian Pelz · Wolfenbüttel, DE
• Maik Habermann · Osterode, DE
• Michael Braun · Altensteig, DE
• Stefan Mecke · Vechelde, DE
• Ansgar Geffert · Hohenhameln, DE
• Nils Köpper · Harsum, DE

Key dates

• Filing date: Jul 28, 2020
• Grant date: Nov 29, 2022
• Expiry date: Feb 9, 2041

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/12965
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

The invention relates to a method for producing a hot-rolled strip composed of a bainitic multi-phase steel and having a Zn—Mg—Al coating, comprising the following steps: melting a steel melt containing (in weight percent): C: 0.04-0.11, Si: <=0.7, Mn: 1.4-2.2, Mo: 0.05-0.5, Al: 0.015-0.1, P: up to 0.02, S: up to 0.01, B: up to 0.006, and at least one element from the group Nb, V, Ti in accordance with the following condition: 0.02<=Nb+V+Ti<=0.20, the remainder being iron including unavoidable steel-accompanying elements resulting from the melting process, casting the steel melt into a preliminary material, in particular a slab or a block or a thin slab, hot rolling the preliminary material into a hot-rolled strip having a final rolling temperature in the range of 800 to 950° C., cooling the hot-rolled strip to a winding temperature less than 650° C., winding the hot-rolled strip at a winding temperature less than 650° C., cooling the wound hot-rolled strip to room temperature in still air, wherein the microstructure of the wound hot-rolled strip then has a bainite fraction greater than 50% after the hot rolling, heating the hot-rolled strip to a temperature greater than 650° C. an…