Arcelormittal

Eta Sa Manufacture Horlogere Suisse

Arcelormittal Investigacion Y Desarrollo, S.l.

Samuel Vignier

Jean-Luc Helfer

Christian Charbon

Astrid Perlade

Artem Arlazarov

Frédéric Kegel

Frederic Kegel

Serge Nicoud

Frédéric Kohler

Sébastien Roder

A spot welded joint of at least two steel sheets is provided. At least one of the steel sheets presents yield strength above or equal to 600 MPa, an ultimate tensile strength above or equal to 1000 MPa, uniform elongation above or equal to 15%. The base metal chemical composition includes 0.05≤C≤0.21%, 4.0≤Mn≤7.0%, 0.5≤Al≤3.5%, Si≤2.0%, Ti≤0.2%, V≤0.2%, Nb≤0.2%, P≤0.025%, B≤0.0035%, and the spot welded joint contains a molten zone microstructure containing more than 0.5% of Al and containing a surface fraction of segregated areas lower than 1%, said segregated areas being zones larger than 20 μmand containing more than the steel nominal phosphorus content.

Production method for a spot welded joint using high strength and high forming steel

A spot welded joint of at least two steel sheets is provided. At least one of the steel sheets presents yield strength above or equal to 600 MPa, an ultimate tensile strength above or equal to 1000 MPa, uniform elongation above or equal to 15%. The base metal chemical composition includes 0.05&#x2264;C&#x2264;0.21%, 4.0&#x2264;Mn&#x2264;7.0%, 0.5&#x2264;Al&#x2264;3.5%, Si&#x2264;2.0%, Ti&#x2264;0.2%, V&#x2264;0.2%, Nb&#x2264;0.2%, P&#x2264;0.025%, B&#x2264;0.0035%, and the spot welded joint contains a molten zone microstructure containing more than 0.5% of Al and containing a surface fraction of segregated areas lower than 1%, said segregated areas being zones larger than 20 &#x3bc;mand containing more than the steel nominal phosphorus content.

Spot welded joint using high strength and high forming steel and its production method

The present invention provides a spot welded joint of at least two steel sheets. At least one of the steel sheets presents yield strength above or equal to 600 MPa, an ultimate tensile strength above or equal to 1000 MPa, uniform elongation above or equal to 15%. The base metal chemical composition includes 0.05&#x2264;C&#x2264;0.21%, 4.0&#x2264;Mn&#x2264;7.0%, 0.5&#x2264;Al&#x2264;3.5%, Si&#x2264;2.0%, Ti&#x2264;0.2%, V&#x2264;0.2%, Nb&#x2264;0.2%, P&#x2264;0.025%, B&#x2264;0.0035%, and the spot welded joint contains a molten zone microstructure containing more than 0.5% of Al and containing a surface fraction of segregated areas lower than 1%, said segregated areas being zones larger than 20 &#x3bc;mand containing more than the steel nominal phosphorus content.

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Pont Astier, France

Samuel Vignier