Arcelormittal France

Damien Ormston

Pascal Drillet

A hot-rolled steel sheet having a tensile strength greater than 800 MPa and an elongation at break greater than 10% is provided. A composition of the steel includes, the contents being expressed by weight: 0.050%&#x2264;C&#x2264;0.090%, 1%&#x2264;Mn&#x2264;2%, 0.015%&#x2264;Al&#x2264;0.050%, 0.1%&#x2264;Si&#x2264;0.3%, 0.10%&#x2264;Mo&#x2264;0.40%, S&#x2264;0.010%, P&#x2264;0.025%, 0.003%&#x2264;N&#x2264;0.009%, 0.12%&#x2264;V&#x2264;0.22%, Ti&#x2264;0.005%, Nb&#x2264;0.020% and optionally, Cr&#x2264;0.45%. A balance of the composition includes iron and inevitable impurities resulting from the smelting. A microstructure of the sheet or part includes, as a surface fraction, at least 80% upper bainite, and a remainder includes lower bainite, martensite and residual austenite. A sum of the martensite and residual austenite, as a surface fraction, is less than 5%.

Steel sheet having high tensile strength and ductility

The invention relates to a hot-rolled steel sheet having a tensile strength greater than 800 MPa and an elongation at break greater than 10%, the composition of which comprises, the contents being expressed by weight: 0.050%&#x2264;C&#x2264;0.090%, 1%&#x2264;Mn&#x2264;2%, 0.015%&#x2264;Al&#x2264;0.050%, 0.1%&#x2264;Si&#x2264;0.3%, 0.10%&#x2264;Mo&#x2264;0.40%, S&#x2264;0.010%, P&#x2264;0.025%, 0.003%&#x2264;N&#x2264;0.009%, 0.12%&#x2264;V&#x2264;0.22%, Ti&#x2264;0.005%, Nb&#x2264;0.020% and, optionally, Cr&#x2264;0.45%, the balance of the composition consisting of iron and inevitable impurities resulting from the smelting, the microstructure of the sheet or the part comprising, as a surface fraction, at least 80% upper bainite, the possible complement consisting of lower bainite, martensite and residual austenite, the sum of the martensite and residual austenite contents being less than 5%.

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Dunkirk, France

Damien Ormston