CPC C21D 9/46 (2013.01) [B32B 15/013 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/0205 (2013.01); C21D 8/0226 (2013.01); C21D 8/0236 (2013.01); C21D 8/0268 (2013.01); C21D 8/0273 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C21D 2211/001 (2013.01); C21D 2211/004 (2013.01); C21D 2211/005 (2013.01)] | 17 Claims |
1. A cold rolled and annealed steel sheet comprising 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%, and,
optionally, one or more elements chosen among Ni, Cr and Cu in an individual amount of up to 3% and, optionally, one or more elements chosen among B, Ta, Zr, Nb, V, Ti, Mo, and W in accumulated amount of up to 2.0%, a remainder of the composition being made up of iron and inevitable impurities resulting from processing,
a microstructure of the cold rolled and annealed steel sheet including, by volume fraction, ordered ferrite between 1% and 10%, and 1%<kappa carbides 10%, by volume fraction, the kappa carbides including both intragranular kappa carbides and intergranular kappa carbides, a remainder being austenite, a density of the steel sheet being equal or below 7.2 and an FWHM for the austenite matrix is between 0.700° and 1.100°, wherein FWHM is a measurement by X-ray diffraction of the full width at half maximum (FWHM) of the diffraction peak corresponding to the planes.
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