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1. (WO2017203347) COLD ROLLED AND ANNEALED STEEL SHEET, METHOD OF PRODUCTION THEREOF AND USE OF SUCH STEEL TO PRODUCE VEHICLE PARTS

Pub. No.:    WO/2017/203347    International Application No.:    PCT/IB2017/000619
Publication Date: Fri Dec 01 00:59:59 CET 2017 International Filing Date: Wed May 24 01:59:59 CEST 2017
IPC: C22C 38/00
C22C 38/02
C22C 38/04
C22C 38/06
C21D 8/02
C21D 8/04
Applicants: ARCELORMITTAL
Inventors: SOLER, Michel
GARAT, Xavier
Title: COLD ROLLED AND ANNEALED STEEL SHEET, METHOD OF PRODUCTION THEREOF AND USE OF SUCH STEEL TO PRODUCE VEHICLE PARTS
Abstract:
The invention deals with a cold rolled and annealed steel sheet comprising by weight : 0.6 ≤ C ≤ 1.3%, 15.0 ≤ Mn ≤ 35%, 5 ≤ AI ≤ 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 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 pm 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 pm and below 3.0. It also deals with a manufacturing method and with use of such grade for making vehicle parts.