Arcelormittal

Irène De Diego Calderon

Jean-Christophe Hell

Ian Alberto Zuazo Rodriguez

Xavier Garat

Michel Soler

A cold rolled and annealed steel sheet including by weight: 0.6<C<1.3%, 15≤Mn<35%, 6≤Al<15%, Si≤2.40%, S≤0.03%, P≤0.1%, N≤0.1%, possibly one or more optional elements chosen among Ni, Cr and Cu in an individual amount of up to 3% and possibly one or more elements chosen among B, Ta, Zr, Nb, V, Ti, Mo, and W in a cumulated amount of up to 2.0%, the remainder of the composition making up of iron and inevitable impurities resulting from the elaboration, the microstructure of the sheet including of ordered ferrite between 1% and 10%, optionally of up to 10% of kappa carbides, the remainder being made of austenite, and, the density of the steel sheet being equal or below 7.2 and the FWHM for the austenite matrix is between 0.700 and 1.100.

Cold rolled and annealed steel sheet, method of production thereof and use of such steel to produce vehicle parts

A cold rolled and annealed steel sheet includes by weight: 0.6&#x3c;C&#x3c;1.3%,15.0&#x3c;Mn&#x3c;35%, 6.0&#x3c;Al&#x3c;15%, Si&#x3c;2.40%, S&#x3c;0.015%, P&#x3c;0.1%, N&#x3c;0.1%, iron and inevitable impurities, optionally one or more of Ni, Cr and Cu in an individual amount of up to 3% and optionally one or more of B, Ta, Zr, Nb, V, Ti, Mo, and W in a cumulated amount of up to 2.0%, a microstructure of the sheet comprising at least 0.1% of intragranular kappa carbides, at least 80% of the kappa carbides have an average size below 30 nm, the remainder being made of austenite, an average grain size of the austenite being below 6 &#x3bc;m, an average aspect ratio of the austenite being between 1.5 and 6, an average grain size of the ferrite, when present being below 5 &#x3bc;m, and an average aspect ratio of the ferrite, when present, being below 3.0.

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Metz, France

Irène De Diego Calderon