Arcelormittal

Arcelormittal Investigacion Y Desarrollo, S.l.

Catherine Vinci

Antoine Moulin

Gloria Restrepo Gacess

Tom Watershoot

Veronique Sardoy

Mohamed Goune

Sebastian Cobo

Martin Beauvais

Véronique Hebert

Juan David Puerta Velasquez

Tom Waterschoot

Gloria Restrepo Garces

The present invention provides a cold-rolled and annealed Dual-Phase steel sheet having a tensile strength from 980 to 1100 MPa. The composition includes the contents being expressed by weight: 0.055%≤C≤0.095%, 2%≤Mn≤2.6%, 0.005%≤Si≤0.35%, S≤0.005%, P≤0.050%, 0.1≤Al≤0.3%, 0.05%≤Mo≤0.25%, 0.2%≤Cr≤0.5%, Cr+2 Mo≤0.6%, Ni≤0.1%, 0.010≤Nb≤0.040%, 0.010≤Ti≤0.050%, 0.0005≤B≤0.0025%, and 0.002%≤N≤0.007%. The remainder of the composition includes iron and inevitable impurities resulting from the smelting. A microstructure of the steel sheet is 40 to 65% ferrite, 35 to 50% martensite and 0 to 10% bainite. A non-recrystallized ferrite fraction is less than or equal to 15%.

Very high-strength, cold-rolled, dual steel sheets

The present invention provides a cold-rolled and annealed Dual-Phase steel sheet having strength from 980 to 1100 MPa and a breaking elongation greater than 9%. The composition includes the contents being expressed by weight: 0.055%&#x2264;C&#x2264;0.095%, 2%&#x2264;Mn&#x2264;2.6%, 0.005%&#x2264;Si&#x2264;0.35%, S&#x2264;0.005%, P&#x2264;0.050%, 0.1&#x2264;Al&#x2264;0.3%, 0.05%&#x2264;Mo&#x2264;0.25%, 0.2%&#x2264;Cr&#x2264;0.5%, Cr+2Mo&#x2264;0.6%, Ni&#x2264;0.1%, 0.010&#x2264;Nb&#x2264;0.040%, 0.010&#x2264;Ti&#x2264;0.050%, 0.0005&#x2264;B&#x2264;0.0025%, and 0.002%&#x2264;N&#x2264;0.007%. The remainder of the composition includes iron and inevitable impurities resulting from the smelting. A manufacturing method is also provided.

Manufacturing method for very high-strength, cold-rolled, dual-phase steel sheets

The present invention provides a rolled steel sheet, for press hardening, for which the chemical composition includes, with contents expressed by weight, 0.24%&#x2266;C&#x2266;0.38%, 0.40%&#x2266;Mn&#x2266;3%, 0.10%&#x2266;Si&#x2266;0.70%, 0.015%&#x2266;Al&#x2266;0.070%, 0%&#x2266;Cr&#x2266;2%, 0.25%&#x2266;Ni&#x2266;2%, 0.015%&#x2266;Ti&#x2266;0.10%, 0%&#x2266;Nb&#x2266;0.060%, 0.0005%&#x2266;B&#x2266;0.0040%, 0.003%&#x2266;N&#x2266;0.010%, 0.0001%&#x2266;S&#x2266;0.005%, 0.0001%&#x2266;P&#x2266;0.025%, it being understood that the titanium and nitrogen content satisfy: Ti/N&#x3e;3.42, and that the carbon, manganese, chromium and silicon content satisfy: with the chemical composition optionally including one or more of the following elements: 0.05%&#x2266;Mo&#x2266;0.65%, 0.001%&#x2266;W&#x2266;0.30%, 0.0005%&#x2266;Ca&#x2266;0.005%, with the remainder made up of iron and inevitable impurities coming from preparation. The sheet includes a nickel content Niat any point of the steel near the surface of said sheet over a depth &#x394;, such that Ni&#x3e;Ni, where Nidesignates the nominal nickel content of the steel, and such that Nidesignates the maximum nickel content within &#x394;: and such that: with the depth &#x394; expressed in microns and the Niand Nicontents expressed in percentages by weight.

Method for fabricating steel sheet for press hardening, and parts obtained by this method

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Jury, France

Catherine Vinci