US2024384378A1PendingUtilityA1
Hot-rolled steel sheet
Est. expiryOct 11, 2041(~15.2 yrs left)· nominal 20-yr term from priority
C22C 38/14C22C 38/12C22C 38/06C22C 38/02C22C 38/002C21D 2211/009C21D 2211/005C21D 2211/001C21D 9/46C21D 8/0226C22C 38/008C22C 38/001C22C 38/52C22C 38/54C22C 38/42C22C 38/44C22C 38/46C22C 38/48C22C 38/50C22C 38/60C22C 38/10C22C 38/005C22C 38/32C22C 38/08C22C 38/34C22C 38/38C22C 38/16C22C 38/04C21D 6/005C21D 8/0263C21D 8/02C22C 38/58
60
PatentIndex Score
0
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References
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Claims
Abstract
This hot-rolled steel sheet has a predetermined chemical composition, has a microstructure including, by area %, residual austenite of less than 3.0%, ferrite of 15.0% or more and less than 60.0%, and pearlite of less than 5.0%, in which an entropy value obtained by analyzing an SEM image of the microstructure using a gray-level co-occurrence matrix method is 10.7 or more, an inverse difference normalized value is 1.020 or more, a cluster shade value is −8.0×10 5 to 8.0×10 5 , and a standard deviation of an Mn concentration is 0.60 mass % or less, and has a tensile strength of 980 MPa or more.
Claims
exact text as granted — not AI-modified1 . A hot-rolled steel sheet comprising, as a chemical composition, by mass %:
C: 0.050% to 0.250%; Si: 0.05% to 3.00%; Mn: 1.00% to 4.00%; sol. Al: 0.001% to 2.000%; P: 0.100% or less; S: 0.0300% or less; N: 0.1000% or less; O: 0.0100% or less; Ti: 0% to 0.500%; Nb: 0% to 0.500%; V: 0% to 0.500%; Cu: 0% to 2.00%; Cr: 0% to 2.00%; Mo: 0% to 1.00%; Ni: 0% to 2.00%; B: 0% to 0.0100%; Ca: 0% to 0.0200%; Mg: 0% to 0.0200%; REM: 0% to 0.1000%; Bi: 0% to 0.0200%; As: 0% to 0.100%; Zr: 0% to 1.00%; Co: 0% to 1.00%; Zn: 0% to 1.00%; W: 0% to 1.00%; Sn: 0% to 0.05%; and a remainder: Fe and impurities, wherein Expressions (A) and (B) are satisfied, a microstructure includes, by area %,
residual austenite of less than 3.0%,
ferrite of 15.0% or more and less than 60.0%, and
pearlite of less than 5.0%,
in which an entropy value represented by Expression (1), obtained by analyzing an SEM image of the microstructure using a gray-level co-occurrence matrix method, is 10.7 or more,
an inverse difference normalized value represented by Expression (2) is 1.020 or more,
a cluster shade value represented by Expression (3) is −8.0×10 5 to 8.0×10 5 , and
a standard deviation of an Mn concentration is 0.60 mass % or less, and
a tensile strength is 980 MPa or more,
0.06
%
≤
Ti
+
Nb
+
V
≤
0.5
%
(
A
)
Zr
+
Co
+
Zn
+
W
≤
1.
%
(
B
)
where each element symbol in Expressions (A) and (B) represents an amount of the corresponding element by mass %, and 0% is substituted in a case where the corresponding element is not contained,
here, P(i, j) in Expressions (1) to (5) is a gray-level co-occurrence matrix, L in Expression (2) is the number of grayscale levels that can be taken in the SEM image, i and j in Expressions (2) and (3) are natural numbers of 1 to L, and μ x and μ y in Expression (3) are each represented by Expressions (4) and (5),
Entropy
=
-
∑
i
∑
j
P
(
i
,
j
)
·
log
(
P
(
i
,
j
)
)
(
1
)
Inverse
difference
normalized
=
∑
i
∑
j
P
(
i
,
j
)
1
+
❘
"\[LeftBracketingBar]"
i
-
j
❘
"\[RightBracketingBar]"
L
(
2
)
Cluster
Shade
=
∑
i
∑
j
(
i
+
j
-
μ
x
-
μ
y
)
3
P
(
i
,
j
)
(
3
)
μ
x
=
∑
i
∑
j
i
(
P
(
i
,
j
)
)
(
4
)
μ
y
=
∑
i
∑
j
j
(
P
(
i
,
j
)
)
.
_
(
5
)
2 . The hot-rolled steel sheet according to claim 1 ,
wherein an average crystal grain size of a surface layer is less than 3.0 μm.
3 . The hot-rolled steel sheet according to claim 1 ,
wherein the chemical composition contains, by mass %, one or more of Ti: 0.001% to 0.500%, Nb: 0.001% to 0.500%, V: 0.001% to 0.500%, Cu: 0.01% to 2.00%, Cr: 0.01% to 2.00%, Mo: 0.01% to 1.00%, Ni: 0.01% to 2.00%, B: 0.0001% to 0.0100%, Ca: 0.0001% to 0.0200%, Mg: 0.0001% to 0.0200%, REM: 0.0001% to 0.1000%, Bi: 0.0001% to 0.0200%, As: 0.001% to 0.100%, Zr: 0.01% to 1.00%, Co: 0.01% to 1.00%, Zn: 0.01% to 1.00%, W: 0.01% to 1.00%, and Sn: 0.01% to 0.05%.
4 . The hot-rolled steel sheet according to claim 2 ,
wherein the chemical composition contains, by mass %, one or more of Ti: 0.001% to 0.500%, Nb: 0.001% to 0.500%, V: 0.001% to 0.500%, Cu: 0.01% to 2.00%, Cr: 0.01% to 2.00%, Mo: 0.01% to 1.00%, Ni: 0.01% to 2.00%, B: 0.0001% to 0.0100%, Ca: 0.0001% to 0.0200%, Mg: 0.0001% to 0.0200%, REM: 0.0001% to 0.1000%, Bi: 0.0001% to 0.0200%, As: 0.001% to 0.100%, Zr: 0.01% to 1.00%, Co: 0.01% to 1.00%, Zn: 0.01% to 1.00%, W: 0.01% to 1.00%, and Sn: 0.01% to 0.05%.Join the waitlist — get patent alerts
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