The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 25, 2013
Filed:
Jun. 11, 2008
Florence Bertrand, Scy-Chazelles, FR;
Didier Huin, Nancy, FR;
Hubert Saint-raymond, Metz, FR;
ArcelorMittal France, Saint Denis, FR;
Abstract
The invention deals with a process for manufacturing a hot-dip galvanized or galvannealed steel sheet having a TRIP microstructure, said process comprising the steps consisting in: -providing a steel sheet whose composition comprises, by weight: 0.01≦C≦0.22%, 0.50≦Mn≦2.0%, 0.2≦Si≦2.0%, 0.005≦Al≦2.0%, Mo<1.0%, Cr≦1.0%, P<0.02%, Ti≦0.20%, V≦0.40%, Ni≦1.0%, Nb≦0.20%, the balance of the composition being iron and unavoidable impurities resulting from the smelting, -oxidizing said steel sheet in a direct flame furnace where the atmosphere comprises air and fuel with an air-to-fuel ratio between 0.80 and 0.95, so that a layer of iron oxide having a thickness from 0.05 to 0.2 μm is formed on the surface of the steel sheet, and an internal oxide of Si and/or Mn and/or Al is formed, -reducing said oxidized steel sheet, at a reduction rate from 0.001 to 0.010 μm/s, in order to achieve a reduction of the layer of iron oxide, -hot-dip galvanising said reduced steel sheet to form a zinc-coated steel sheet, and -optionally, subjecting said hot-dip coated steel sheet to an alloying treatment to form a galvannealed steel sheet.