US2019352750A1PendingUtilityA1
High strength cold rolled steel sheet for automotive use
Est. expiryNov 25, 2036(~10.3 yrs left)· nominal 20-yr term from priority
C21D 8/02C21D 6/002C21D 2211/008C22C 38/06C22C 38/18C22C 38/04C22C 38/02C21D 2211/002C21D 8/0236C21D 8/0263C21D 2211/001C21D 8/0226C21D 2211/005C21D 9/46C22C 38/12C22C 38/26C22C 38/38C21D 8/0205
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Claims
Abstract
A high strength cold rolled steel sheet has a composition consisting of the following elements (in wt. %): C 0.07-0.15, Mn 2.3-3.2, Si 0.6-1.2, Cr 0.05-0.5, Al≤0.2 Nb≤0.1, balance Fe apart from impurities, a multiphase microstructure comprising a matrix of bainitic ferrite, and a tensile strength (Rm) of 980-1100 MPa.
Claims
exact text as granted — not AI-modified1 . A high strength cold rolled steel sheet having;
a) a composition consisting of the following elements (in wt. %)
C
0.07-0.13
Mn
2.3-3.1
Si
0.65-1.2
Cr
0.05-0.5
Al
≤0.2
Nb
≤0.05
balance Fe apart from impurities,
b) a multiphase microstructure comprising a matrix of bainitic ferrite and ≤10 volume % polygonal ferrite, and
c) a tensile strength (R m ) of 980-1100 MPa.
2 . The high strength cold rolled steel sheet according to claim 1 , fulfilling at least one of the following requirements:
a) a composition fulfilling at least one of the following requirements (in wt. %)
C
0.08-0.13
Mn
2.4-3.1
Si
0.7-1.1
Cr
0.05-0.45
Al
0.005-0.1
Nb
≤0.05
wherein the impurities fulfil at least one of the requirements
Ti
≤0.05
Mo
≤0.05
N
≤0.015
B
≤0.05
balance Fe apart from impurities,
b) a multiphase microstructure comprising at least one of (in vol. %)
retained austenite
2-20
martensite
≤15
bainitic ferrite
≥50
polygonal ferrite
≤10,
and
c) at least one of the following mechanical properties
tensile strength (R m )
990-1100 MPa
yield strength (R p0.2 )
580-920 MPa
total elongation (A 50 )
≥13%
hole expansion ratio (λ)
≥50%
yield ratio (R p0.2 /R m )
≥0.75.
3 . The high strength cold rolled steel sheet according to claim 1 , having:
a) a composition fulfilling at least one of the following requirements (in wt. %)
C
0.08-0.13
Mn
2.5-3.0
Si
0.75-1.05
Cr
0.1-0.4
Si + Cr
0.9-1.3
Al
0.01-0.08
Nb
≤0.01
wherein the impurities fulfil at least one of the requirements
Ti
≤0.02
V
≤0.02
Mo
≤0.03
N
≤0.008
B
≤0.003
balance Fe apart from impurities,
b) a multiphase microstructure comprising (in vol. %)
retained austenite
5-15
martensite
≤10
bainitic ferrite
≥60
polygonal ferrite
≤5,
and
c) at least one of the following mechanical properties
tensile strength (R m )
1000-1100 MPa
yield strength (R p0.2 )
750-900 MPa
hole expansion ratio (λ)
≥60%
yield ratio (R p0.2 /R m )
0.76-0.85.
4 . The high strength cold rolled steel sheet according to claim 1 , fulfilling at least one of the following requirements:
a) a composition fulfilling at least one of the following requirements (in wt. %)
C
0.09-0.12
Mn
2.5-2.9
Si
0.75-1.0
Cr
0.1-0.3
Si + Cr
0.9-1.2
Al
0.01-0.05
wherein the impurities fulfil at least one of the requirements
Ti
≤0.01
V
≤0.02
Mo
≤0.03
N
≤0.008
B
≤0.003
balance Fe apart from impurities, and
b) at least one of the following mechanical properties
tensile strength (R m )
≥1020 MPa
yield strength (R p0.2 )
≥800 MPa
yield ratio (R p0.2 /R m )
≥0.78.
5 . The high strength cold rolled steel sheet according to claim 1 , fulfilling the following requirements:
a) a composition consisting of (in wt. %)
C
0.08-0.13
Mn
2.4-3.1
Si
0.7-1.1
Cr
0.05-0.45
Al
0.005-0.1
Nb
≤0.05
wherein the impurities fulfil the requirements
Ti
≤0.05
Mo
≤0.05
N
≤0.015
B
≤0.005
balance Fe apart from impurities, and/or
b) a multiphase microstructure comprising (in vol. %)
retained austenite
2-20
martensite
≤15
bainitic ferrite
≥50
polygonal ferrite
≤10.
and/or
c) the following mechanical properties
tensile strength (R m )
1000-1100 MPa
yield strength (R p0.2 )
580-920 MPa
total elongation (A 50 )
≥13%
hole expansion ratio (λ)
≥50%
yield ratio (R p0.2 /R m )
≥0.84.
6 . The high strength cold rolled steel sheet according to claim 3 , fulfilling the following requirements:
a) a composition fulfilling the following requirements (in wt. %)
C
0.08-0.13
Mn
2.5-3.0
Si
0.7-1.1
Cr
0.1-0.4
Si + Cr
0.9-1.3
Al
0.01-0.08
wherein the impurities fulfil the requirements
Ti
≤0.02
V
≤0.02
Mo
≤0.03
N
≤0.008
B
≤0.003
balance Fe apart from impurities, and/or
b) a multiphase microstructure comprising (in vol. %)
retained austenite
5-15
martensite
≤10
bainitic ferrite
≥60
polygonal ferrite
≤5,
and/or
c) the following mechanical properties
tensile strength (R m )
1000-1100 MPa
yield strength (R p0.2 )
750-900 MPa
hole expansion ratio (λ)
≥60%
yield ratio (R p0.2 /R m )
0.78-0.83.
7 . The high strength cold rolled steel sheet according to claim 1 , fulfilling the following requirements:
a) a composition fulfilling the following requirements (in wt. %)
C
0.09-0.12
Mn
2.5-2.9
Si
0.7-1.1
Cr
0.1-0.3
Si + Cr
0.9-1.2
Al
0.01-0.05
wherein the impurities fulfil the requirements
Ti
≤0.01
V
≤0.02
Mo
≤0.03
N
≤0.008
B
≤0.003
balance Fe apart from impurities, and/or
b) the following mechanical properties
tensile strength (R m )
1000-1100 MPa
yield strength (R p0.2 )
750-920 MPa
total elongation (A 50 )
≥13%
hole expansion ratio (λ)
≥50%
yield ratio (R p0.2 /R m )
0.78-0.82.
8 . The high strength cold rolled steel sheet according to claim 1 , wherein a thickness of the cold rolled sheet is 1.0-1.6 mm.
9 . The high strength cold rolled steel sheet according to claim 1 , wherein a total content of bainitic ferrite and tempered martensite is 70-90 vol. %.
10 . The high strength cold rolled steel sheet according to claim 1 , wherein a product of the tensile strength (R m ) and a total elongation (A 50 ) is ≥13000 MPa %.Join the waitlist — get patent alerts
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