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1. (EP3395993) HIGH YIELD RATIO TYPE HIGH-STRENGTH COLD-ROLLED STEEL SHEET AND MANUFACTURING METHOD THEREOF

Office : European Patent Office
Application Number: 16879274 Application Date: 19.12.2016
Publication Number: 3395993 Publication Date: 31.10.2018
Publication Kind : A1
Designated States: AL, AT, BA, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LI, LT, LU, LV, MC, ME, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, SM, TR
Prior PCT appl.: Application Number:KR2016014856 ; Publication Number: Click to see the data
IPC:
C22C 38/38
C21D 6/00
C21D 8/02
C21D 9/46
C22C 38/00
C22C 38/02
C22C 38/06
C22C 38/26
C22C 38/28
C22C 38/32
C CHEMISTRY; METALLURGY
22
METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
C
ALLOYS
38
Ferrous alloys, e.g. steel alloys
18
containing chromium
38
with more than 1.5% by weight of manganese
C CHEMISTRY; METALLURGY
21
METALLURGY OF IRON
D
MODIFYING 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
6
Heat treatment of ferrous alloys
C CHEMISTRY; METALLURGY
21
METALLURGY OF IRON
D
MODIFYING 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
8
Modifying the physical properties by deformation combined with, or followed by, heat treatment
02
during manufacturing of plates or strips
C CHEMISTRY; METALLURGY
21
METALLURGY OF IRON
D
MODIFYING 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
9
Heat treatment, e.g. annealing, hardening, quenching, tempering, adapted for particular articles; Furnaces therefor
46
for sheet metals
C CHEMISTRY; METALLURGY
22
METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
C
ALLOYS
38
Ferrous alloys, e.g. steel alloys
C CHEMISTRY; METALLURGY
22
METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
C
ALLOYS
38
Ferrous alloys, e.g. steel alloys
02
containing silicon
C CHEMISTRY; METALLURGY
22
METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
C
ALLOYS
38
Ferrous alloys, e.g. steel alloys
06
containing aluminium
C CHEMISTRY; METALLURGY
22
METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
C
ALLOYS
38
Ferrous alloys, e.g. steel alloys
18
containing chromium
26
with niobium or tantalum
C CHEMISTRY; METALLURGY
22
METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
C
ALLOYS
38
Ferrous alloys, e.g. steel alloys
18
containing chromium
28
with titanium or zirconium
C CHEMISTRY; METALLURGY
22
METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
C
ALLOYS
38
Ferrous alloys, e.g. steel alloys
18
containing chromium
32
with boron
CPC:
C22C 38/38
C21D 6/002
C21D 6/005
C21D 6/008
C21D 8/0205
C21D 8/0226
C21D 8/0236
C21D 8/0247
C21D 8/0273
C21D 9/46
C21D 2211/002
C21D 2211/005
C21D 2211/008
C22C 38/001
C22C 38/02
C22C 38/06
C22C 38/26
C22C 38/28
C22C 38/32
Applicants: POSCO
Inventors: KOO MIN-SEO
HAN SEONG-HO
Priority Data: 20150185502 23.12.2015 KR
2016014856 19.12.2016 KR
Title: (DE) HOCHFESTES KALTGEWALZTES STAHLBLECH MIT HOHEM STRECKGRENZENVERHÄLTNIS UND HERSTELLUNGSVERFAHREN DAFÜR
(EN) HIGH YIELD RATIO TYPE HIGH-STRENGTH COLD-ROLLED STEEL SHEET AND MANUFACTURING METHOD THEREOF
(FR) TÔLE D'ACIER HAUTE RÉSISTANCE LAMINÉE À FROID DE TYPE À HAUTE LIMITE D'ÉLASTICITÉ ET SON PROCÉDÉ DE FABRICATION
Abstract: front page image
(EN) A preferred aspect of the present invention is a cold-rolled steel sheet manufactured by a cold-rolled steel sheet manufacturing method comprising a continuous annealing step, which has a composition comprising, in percentage by weight: C: 0.1-0.15%; Si: 0.2% or less (including 0%); Mn: 2.3-3.0%; P: 0.001-0.10%; S: 0.010% or less (including 0%); Sol.Al: 0.01-0.10%; N: 0.010% or less (excluding 0%); Cr: 0.3-0.9%; B: 0.0010-0.0030%; Ti: 0.01-0.03%; Nb:0.01-0.03%; the balance being Fe and other impurities, and satisfies following relational expression (1). [Relational expression 1] 1650 ‰¤ 5541.4C + 239Mn + 169.1Cr + 0.74SS - 1.36RCS ‰¤ 1688 [wherein C, Mn and Cr are values representing the contents of the respective elements in weight%, SS represents a continuous annealing temperature (°C), and RCS represents a cooling end temperature (°C) in continuous annealing]. The present invention provides a high yield ratio type high strength cold-rolled steel sheet and the manufacturing method thereof, in which microstructure comprises, in area percentage, at least 90% of martensite and tempered martensite; and 10% or less of ferrite and bainite, in which the fraction of the tempered martensite in the martensite and the tempered martensite is 90% or more, in area percentage, and the ratio (b/a) of the C + Mn concentration (a) in the martensite to the C + Mn concentration (b) in the ferrite and the bainite is 0.65 or more.
(FR) Un aspect préféré de la présente invention concerne une tôle d'acier laminée à froid fabriquée par un procédé de fabrication de tôle d'acier laminée à froid comprenant une étape de recuit continu, qui présente une composition comprenant, en pourcentage en poids : C : 0,1 à 0,15 %; Si : 0,2 % ou moins (y compris 0 %); Mn : 2,3 à 3,0 %; P : 0,001 à 0,10 %; S : 0,010 % ou moins (y compris 0 %), Al sol. : 0,01 à 0,10 %; N : 0,010 % ou moins (0 % exclus); Cr : 0,3 à 0,9 %; B : 0,0010 à 0,0030 %; Ti : 0,01 à 0,03 %; Nb : 0,01 à 0,03 %; le reste étant du Fe et les inévitables impuretés, et satisfaisant l'expression de relation suivante : [Expression de relation 1] 1650 ≤ 5541,4C + 239Mn + 169,1Cr + 0,74SS - 1,36RCS ≤ 1688 [où C, Mn et Cr sont des valeurs représentant la teneur des éléments respectifs en % en poids, SS représente une température de recuit continu (℃) et RCS représente une température finale de refroidissement (℃) dans le recuit continu]. L'invention permet d'obtenir une tôle d'acier haute résistance laminée à froid de type à haute limite d'élasticité et son procédé de fabrication, la microstructure de ladite tôle comprenant, en pourcentage de surface, au moins 90 % de martensite et de martensite revenue; et 10 % ou moins de ferrite et de bainite, la fraction de la martensite revenue dans la martensite et la martensite revenue étant supérieure ou égale à 90 %, en pourcentage de surface, et le rapport (b/a) de la concentration de C + Mn (a) dans la martensite à la concentration de C + Mn (b) dans la ferrite et la bainite étant supérieur ou égal à 0,65.
Also published as:
CN108431280US20180363090WO/2017/111407