Method for melt immersion coating of a flat steel product made of high strength steel

US8636854B2 · kind B2 · utility

Assignee

• Thyssenkrupp Steel AG · DE

Inventors

• Ronny Leuschner · Dresden, DE
• Manfred Meurer · Rheinberg, DE
• Wilhelm Warnecke · Hamminkeln, DE
• Sabine Zeizinger · Mülheim, DE
• Gernot Nothacker · Dortmund, DE
• Michael Ullmann · Bochum, DE
• Norbert Schaffrath · Hamm, DE

Key dates

• Filing date: Apr 26, 2006
• Grant date: Jan 28, 2014
• Expiry date: Apr 2, 2027

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C23C2/06
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

A method for coating a flat steel product manufactured from a high strength steel with a metallic coating, wherein the flat steel product is initially subjected to a heat treatment, in order then, in the heated state, to be hot-dip galvanized with the metallic coating in a melting bath containing overall at least 85% zinc and/or aluminum. The heat treatment includes heating the steel product in a reducing atmosphere, followed by converting a surface of the flat product to an iron oxide layer by a heat treatment lasting 1 to 10 secs in an oxidizing atmosphere, followed by annealing in a reducing atmosphere over a period of time which is longer than the duration of the formation of the iron oxide layer such that the iron oxide layer is reduced at least on its surface to pure iron, followed by cooling the product to a melting bath temperature.