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1. EP3778973 - HIGH-STRENGTH SHEET STEEL AND METHOD FOR MANUFACTURING SAME

Office
European Patent Office
Application Number 19777630
Application Date 20.03.2019
Publication Number 3778973
Publication Date 17.02.2021
Publication Kind A4
IPC
C22C 38/06
CCHEMISTRY; METALLURGY
22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
CALLOYS
38Ferrous alloys, e.g. steel alloys
06containing aluminium
C21D 6/00
CCHEMISTRY; METALLURGY
21METALLURGY OF IRON
DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING, OR OTHER TREATMENTS
6Heat treatment of ferrous alloys
C21D 8/02
CCHEMISTRY; METALLURGY
21METALLURGY OF IRON
DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING, OR OTHER TREATMENTS
8Modifying the physical properties by deformation combined with, or followed by, heat treatment
02during manufacturing of plates or strips
C21D 9/46
CCHEMISTRY; METALLURGY
21METALLURGY OF IRON
DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING, OR OTHER TREATMENTS
9Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
46for sheet metals
C22C 38/02
CCHEMISTRY; METALLURGY
22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
CALLOYS
38Ferrous alloys, e.g. steel alloys
02containing silicon
C22C 38/04
CCHEMISTRY; METALLURGY
22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
CALLOYS
38Ferrous alloys, e.g. steel alloys
04containing manganese
CPC
C21D 6/005
CCHEMISTRY; METALLURGY
21METALLURGY OF IRON
DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
6Heat treatment of ferrous alloys
005containing Mn
C21D 6/008
CCHEMISTRY; METALLURGY
21METALLURGY OF IRON
DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
6Heat treatment of ferrous alloys
008containing Si
C21D 8/0226
CCHEMISTRY; METALLURGY
21METALLURGY OF IRON
DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
8Modifying the physical properties by deformation combined with, or followed by, heat treatment
02during manufacturing of plates or strips
0221characterised by the working steps
0226Hot rolling
C21D 8/0236
CCHEMISTRY; METALLURGY
21METALLURGY OF IRON
DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
8Modifying the physical properties by deformation combined with, or followed by, heat treatment
02during manufacturing of plates or strips
0221characterised by the working steps
0236Cold rolling
C21D 8/0263
CCHEMISTRY; METALLURGY
21METALLURGY OF IRON
DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
8Modifying the physical properties by deformation combined with, or followed by, heat treatment
02during manufacturing of plates or strips
0247characterised by the heat treatment
0263following hot rolling
C21D 8/0268
CCHEMISTRY; METALLURGY
21METALLURGY OF IRON
DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
8Modifying the physical properties by deformation combined with, or followed by, heat treatment
02during manufacturing of plates or strips
0247characterised by the heat treatment
0268between cold rolling steps
Applicants JFE STEEL CORP
Inventors ENDO KAZUKI
KAWASAKI YOSHIYASU
TOJI YUKI
FUNAKAWA YOSHIMASA
AOYAMA MAI
Designated States
Priority Data 2018066715 30.03.2018 JP
Title
(DE) HOCHFESTES STAHLBLECH UND VERFAHREN ZUR HERSTELLUNG DAVON
(EN) HIGH-STRENGTH SHEET STEEL AND METHOD FOR MANUFACTURING SAME
(FR) TÔLE D'ACIER À RÉSISTANCE ÉLEVÉE ET PROCÉDÉ DE FABRICATION DE LADITE TÔLE D'ACIER
Abstract
(EN)
A high-strength steel sheet according to the present invention has a steel structure with ferrite being 35% or more and 80% or less, martensite being 5% or more and 35% or less, and tempered martensite being 0% or more and 5% or less in terms of area fraction and retained austenite being 8% or more in terms of volume fraction, in addition, an average grain size of the ferrite being 6 µm or less, an average grain size of the retained austenite being 3 µm or less, and a value obtained by dividing an area fraction of blocky austenite by a sum of area fractions of lath-like austenite and the blocky austenite being 0.6 or more, a value obtained by dividing an average Mn content in the retained austenite by an average Mn content in the ferrite being 1.5 or more, and a value obtained by dividing an average C content in the retained austenite by an average C content in the ferrite being 3.0 or more.

(FR)
L'invention concerne une tôle d'acier à résistance élevée, qui est caractérisée en ce que : la structure d'acier comprend, en termes de proportions surfaciques, de 35 à 80 % de ferrite, de 5 à 35 % de martensite et de 0 à 5 % de martensite revenue, et au moins 8 % d'austénite résiduelle en termes de proportion volumétrique ; en outre, la taille moyenne des particules de cristal de ferrite est de 6 µm ou moins, la taille moyenne des particules de cristal d'austénite résiduelle est de 3 µm ou moins, et la valeur de la proportion surfacique d'austénite en bloc divisée par la proportion surfacique totale d'austénite en lattes et d'austénite en bloc est d'au moins 0,6 ; la valeur de la teneur moyenne en Mn de l'austénite résiduelle divisée par la teneur moyenne en Mn de la ferrite est d'au moins 1,5 ; et la valeur de la teneur moyenne en C de l'austénite résiduelle divisée par la teneur moyenne en C de la ferrite est d'au moins 3,0.

Also published as
MXMX/a/2020/010211
TH2001005668