Steel sheet having very high mechanical properties of strength and ductility

US10308995B2 · kind B2 · utility

Assignee

• ArcelorMittal · LI

Inventors

• Sebastien Allain · Norroy-lès-Pont-à-Mousson, FR
• Jean-Christophe Hell · Metz, FR

Key dates

• Filing date: Jul 24, 2014
• Grant date: Jun 4, 2019
• Expiry date: Feb 3, 2035

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C23C2/40
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

The invention relates to the manufacture of a cold-rolled steel sheet having a strength of more than 900 MPa, an elastic limit of more than 700 MPa and distributed elongation of more than 12%, the composition of which includes, the contents being expressed as weight percentages: 0.26%≤C≤0.45%, 1.0%≤Mn≤3.0%, 1.0%≤Si≤3.0%, Al≤0.10%, 0%≤Cr≤1.5%, S≤0.005%, P≤0.020%, Nb≤0.1%, Ti≤0.020%, V≤0.015%, N≤0.01%, the remainder of the composition being iron and inevitable impurities resulting from the production process. The microstructure, given in surface proportions, comprises 13% to 25% residual austenite and 13% to 30% MA islands, the remainder consisting of bainite and possibly ferrite.