The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 10, 2024
Filed:
Dec. 21, 2016
Arcelormittal, Luxembourg, LU;
Hyun Jo Jun, East Chicago, IN (US);
Pavan Venkatasurya, East Chicago, IN (US);
ARCELORMITTAL, Luxembourg, LU;
Abstract
A method produces a steel sheet having a microstructure including, in area fraction, 20% to 50% intercritical ferrite, 10% to 20% retained austenite, 25% to 45% tempered martensite, 10% to 20% fresh martensite, and bainite. The sum of tempered martensite and bainite is between 30% and 60%. A cold-rolled steel sheet provided includes 0.18% ≤C≤0.25%, 0.9% ≤Si≤1.8%, 0.02% ≤Al≤1.0%, with 1.00% ≤Si+Al≤2.35%, 1.5% ≤Mn≤2.5%, 0.010% ≤Nb ≤0.035%, 0.10% ≤Cr≤0.40%. The steel sheet is annealed to obtain 50% to 80% austenite and 20% to 50% of ferrite, quenched at a cooling rate between 20° C/s and 50° C/s to between Ms-50° C. and Ms-5° C., heated to a partitioning temperature between 375° C. and 450° C. and maintained at the partitioning temperature for at least 50s, then immediately cooled to room temperature.