High formability steel sheet for the manufacture of lightweight structural parts and manufacturing process

US11725265B2 · kind B2 · utility

Assignee

• ArcelorMittal · LI

Inventors

• Frédéric BONNET · Avril, FR
• Manuel Bobadilla · Saulny, FR
• Bertrand Bele · Metz, FR
• Valérie DAESCHLER · Marly, FR

Key dates

• Filing date: May 23, 2022
• Grant date: Aug 15, 2023
• Expiry date: May 23, 2042

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D2211/005
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A steel sheet has a composition comprising, by weight: 0.010%≤C≤0.080%, 0.06%≤Mn≤3%, Si≤1.5%, 0.005%≤Al≤1.5%, S≤0.030%, P≤0.040%, Ti and B such that: 3.2%≤Ti≤7.5% and (0.45×Ti)−1.35≤B≤(0.45×Ti)−0.43, optionally Ni≤1%, Mo≤1%, Cr≤3%, Nb≤0.1%, V≤0.1%, the remainder being iron and unavoidable impurities resulting from the smelting. The steel sheet has a structure consisting of ferrite, at most 10% of austenite, and precipitates comprising eutectic precipitates of TiB2, the volume fraction of TiB2 precipitates with respect to the whole structure being of at least 9%, the proportion of TiB2 precipitates having a surface area lower than 8 μm2 being of at least 96%.