Method for producing a steel strip with improved bonding of metallic hot-dip coatings

US11702729B2 · kind B2 · utility

Assignee

• Salzgitter Flachstahl GmbH · DE

Inventors

• Marc Debeaux · Braunschweig, DE
• Nils Köpper · Harsum, DE

Key dates

• Filing date: Jan 30, 2019
• Grant date: Jul 18, 2023
• Expiry date: Nov 7, 2039

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D9/46
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

A method for producing a steel strip containing, in addition to iron as the main component and unavoidable impurities, one or more of the following oxygen-affine elements in wt. %: Al: more than 0.02, Cr: more than 0.1, Mn: more than 1.3 or Si: more than 0.1, where the surface of the steel strip is cleaned, oxidation-treated and annealed. The treated and annealed steel strip is subsequently coated with a hot-dip coat. In order to be less cost-intensive and to achieve uniform, reproducible adhesion conditions for the coat, the steel strip is oxidation-treated prior to the annealing at temperatures below 200° C., where on the surface of the steel strip, with the formation of oxides with iron from the steel strip, an oxide layer is formed, which contains iron oxide and is reduction-treated during the course of the annealing under a reducing atmosphere to achieve a surface consisting substantially of metallic iron.