	US 11,987,857 B2
	Cold rolled and annealed steel sheet, method of production thereof and use of such steel to produce vehicle parts
Irène De Diego Calderon, Metz (FR); and Jean-Christophe Hell, Metz (FR)
Assigned to ArcelorMittal, Luxembourg (LU)
Appl. No. 17/297,292
Filed by ArcelorMittal, Luxembourg (LU)
PCT Filed Dec. 2, 2019, PCT No. PCT/IB2019/060361 § 371(c)(1), (2) Date May 26, 2021, PCT Pub. No. WO2020/115637, PCT Pub. Date Jun. 11, 2020.
Claims priority of application No. PCT/IB2018/059625 (WO), filed on Dec. 4, 2018.
Prior Publication US 2022/0025478 A1, Jan. 27, 2022
Int. Cl. C21D 9/46 (2006.01); B32B 15/01 (2006.01); C21D 6/00 (2006.01); C21D 8/02 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01)

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.