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1. (US20180363090) HIGH YIELD RATIO TYPE HIGH-STRENGTH COLD-ROLLED STEEL SHEET AND MANUFACTURING METHOD THEREOF

Office : United States of America
Application Number: 16061867 Application Date: 19.12.2016
Publication Number: 20180363090 Publication Date: 20.12.2018
Publication Kind : A1
Prior PCT appl.: Application Number:PCTKR2016014856 ; Publication Number: Click to see the data
IPC:
C21D 9/46
C21D 8/02
C21D 6/00
C22C 38/32
C22C 38/28
C22C 38/26
C22C 38/06
C22C 38/04
C22C 38/02
C22C 38/00
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
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
6
Heat treatment of ferrous 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
18
containing chromium
32
with boron
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
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
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
04
containing manganese
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
CPC:
C21D 2211/002
C21D 2211/005
C21D 2211/008
C21D 6/002
C21D 6/005
C21D 6/008
C21D 8/0205
C21D 8/0226
C21D 8/0236
C21D 8/0263
C21D 9/46
C22C 38/001
C22C 38/002
C22C 38/02
C22C 38/04
C22C 38/06
C22C 38/26
C22C 38/28
C22C 38/32
Applicants: POSCO
Inventors: Min-Seo KOO
Seong-Ho HAN
Priority Data: 10-2015-0185502 23.12.2015 KR
Title: (EN) HIGH YIELD RATIO TYPE HIGH-STRENGTH COLD-ROLLED STEEL SHEET AND MANUFACTURING METHOD THEREOF
Abstract: front page image
(EN)

Provided 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, 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 relationship 1. [relationship 1] 1650≤5541.4C+239Mn+169.1Cr+0.74SS−1.36RCS≤1688, in which microstructure comprises, in area %, 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 %, 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.


Also published as:
CN108431280EP3395993WO/2017/111407