Arcelormittal

Arcelormittal Investigacion Y Desarrollo, S.l.

Laurent Cretteur

Wolfram Ehling

Francis Schmit

Qingdong Yin

A welded steel part with a very high mechanical strength is provided. The welded steel part is obtained by heating followed by hot forming, then cooling of at least one welded blank obtained by butt welding of at least one first and one second sheet. The at least one first and second sheets including, at least in part, a steel substrate and a pre-coating which includes an intermetallic alloy layer in contact with the steel substrate, topped by a metal alloy layer of aluminum or aluminum-based alloy. A method for the fabrication of a welded steel part and the fabrication of structural or safety parts for automotive vehicles are also provided.

Hot-formed previously welded steel part with very high mechanical resistance and production method

The invention relates principally to a welded steel part with a very high mechanical strength characteristics obtained by heating followed by hot forming, then cooling of at least one welded blank obtained by butt welding of at least one first and one second sheet consisting at least in part of a steel substrate and a pre-coating which is constituted by an intermetallic alloy layer in contact with the steel substrate, topped by a metal alloy layer of aluminum or aluminum-based alloy. This welded steel part claimed by the invention is essentially characterized in that the metal alloy layer () has been removed from the edges () in direct proximity to the weld metal zone (), while the intermetallic alloy layer () has been left in place, and in that over at least a portion of the length of the weld metal zone (), the ratio between the carbon content of the weld metal zone () and the carbon content of the substrate () of either the first or the second sheet () having the higher carbon content (Cmax) is between 1.27 and 1.59. The invention likewise relates to a method for the fabrication of a welded steel part as well as the use of this welded steel part for the fabrication of structural or safety parts for automotive vehicles.

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Gouvieux, France

Laurent Cretteur