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1. EP2453032 - HIGH-STRENGTH STEEL SHEET AND MANUFACTURING METHOD THEREFOR

Office European Patent Office
Application Number 10797090
Application Date 29.06.2010
Publication Number 2453032
Publication Date 16.05.2012
Publication Kind A4
IPC
C22C 38/00
CCHEMISTRY; METALLURGY
22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
CALLOYS
38Ferrous alloys, e.g. steel alloys
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 38/14
CCHEMISTRY; METALLURGY
22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
CALLOYS
38Ferrous alloys, e.g. steel alloys
14containing titanium or zirconium
C22C 38/38
CCHEMISTRY; METALLURGY
22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
CALLOYS
38Ferrous alloys, e.g. steel alloys
18containing chromium
38with more than 1.5% by weight of manganese
CPC
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 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
0221characterised by the working steps
0226Hot rolling
C21D 8/0273
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
0247characterised by the heat treatment
0273Final recrystallisation annealing
C21D 2211/004
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
2211Microstructure comprising significant phases
004Dispersions; Precipitations
C21D 2211/005
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 BY DECARBURISATION, TEMPERING OR OTHER TREATMENTS
2211Microstructure comprising significant phases
005Ferrite
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
Applicants JFE STEEL CORP
Inventors NAKAGAWA KOICHI
YOKOTA TAKESHI
SETO KAZUHIRO
KINOSHIRO SATOSHI
TANAKA YUJI
YAMADA KATSUMI
MEGA TETSUYA
NAKAJIMA KATSUMI
Designated States
Priority Data 2009163309 10.07.2009 JP
2010061363 29.06.2010 JP
Title
(DE) HOCHFESTE STAHLPLATTE UND HERSTELLUNGSVERFAHREN DAFÜR
(EN) HIGH-STRENGTH STEEL SHEET AND MANUFACTURING METHOD THEREFOR
(FR) TÔLE D ACIER À HAUTE RÉSISTANCE ET PROCÉDÉ DE FABRICATION ASSOCIÉ
Abstract
(EN)
Provided are a high-strength steel sheet having excellent stretch flangeability after working and a method for producing such a high-strength steel sheet. The composition contains, in mass percent, 0.08% to 0.20% of carbon, 0.2% to 1.0% of silicon, 0.5% to 2.5% of manganese, 0.04% or less of phosphorus, 0.005% or less of sulfur, 0.05% or less of aluminum, 0.07% to 0.20% of titanium, and 0.20% to 0.80% of vanadium, the balance being iron and incidental impurities. In addition, the structure includes 80% to 98% by volume of a ferrite phase and a second phase. Furthermore, the sum of the amounts of titanium and vanadium contained in precipitates having a size of less then 20 nm is 0.150% by mass or more. The difference (HV ± - HV s ) between the hardness of the ferrite phase (HV ± ) and the hardness of a second phase (HV s ) is -300 to 300.

(FR)
L'invention concerne une tôle d'acier à haute résistance qui présente des caractéristiques supérieures de bord tombé post-traitement, et un procédé de fabrication associé. Ladite tôle d'acier se compose, en % en masse, de 0,08 % à 0,20 % de carbone, de 0,2 % à 1 % de silicium, de 0,5 % à 2,5 % de manganèse, jusqu'à 0,04 % de phosphore, jusqu'à 0,005 % de soufre, jusqu'à 0,05 % d'aluminium, de 0,07 % à 0,20 % de titane, et de 0,20 % à 0,80 % de vanadium, le reste comprenant du fer et des impuretés inévitables. En outre, la structure est composée de 80 % à 98 % d'une phase de ferrite et d'une seconde phase en volume. De plus, la quantité totale de titane et de vanadium comprise dans les dépôts ayant une taille inférieure à 20 nm est supérieure à 0,15 % en masse. La différence (HVα-HVS) entre la dureté (HVα) de la phase de ferrite susmentionnée et la dureté (HVS) d'une phase de bainite est de l'ordre de -300 à 300.