ArcelorMittal S.A.
COLD ROLLED AND ANNEALED STEEL SHEET, METHOD OF PRODUCTION THEREOF AND USE OF SUCH STEEL TO PRODUCE VEHICLE PARTS

Abstract:

A cold rolled and annealed steel sheet includes by weight: 0.6.ltoreq.C.ltoreq.1.3%, 15.0.ltoreq.Mn.ltoreq.35%, 5.ltoreq.Al.ltoreq.15%, Si.ltoreq.2.40%, S.ltoreq.0.03%, P.ltoreq.0.1%, N.ltoreq.0.1%, possibly one or more optional elements chosen among Ni, Cr and Cu in an respective amount of up to 4.0%, up to 3.0% and up to 3.0% 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 said sheet comprising optionally up to 3% of kappa carbides, optionally up to 10.0% of granular ferrite, the remainder being made of austenite, the average grain size and average aspect ratio of the austenite being respectively below 6 .mu.m and comprised between 1.5 and 6 and the average grain size and average aspect ratio of the ferrite, when present, being respectively below 5 .mu.m and below 3.0.