Hot-rolled steel sheet and method for manufacturing same
Abstract
An embodiment of the present invention provides a hot-rolled steel sheet comprising, by wt %, 0.06-0.12% of C, 0.004-0.4% of Si, 0.8-2.0% of Mn, 0.01-0.05% of Al, 0.05-1.0% of Cr, 0.001-0.3% of Mo, 0.001-0.05% of P, 0.001-0.005% of S, 0.001-0.01% of N, 0.001-0.05% of Nb, 0.001-0.05% of Ti, 0.001-0.005% of B, and the remainder of Fe and other inevitable impurities, satisfying relational formula 1 below, and having a microstructure including, by area, 80% or more of auto-tempered martensite, and a remainder of at least one of fresh martensite, bainite, and ferrite. [Relational formula 1] (10[C]+[Si]+2.5[Mn])/(1.5[Cr]+2.0[Mo]−3.2[Nb])≤20
Claims
exact text as granted — not AI-modified1 . A hot-rolled steel sheet comprising, by weight:
0.06 to 0.12% of C, 0.004 to 0.4% of Si,0.8 to 2.0% of Mn, 0.01 to 0.05% of Al, 0.05 to 1.0% of Cr, 0.001 to 0.3% of Mo, 0.001 to 0.05% of P, 0.001 to 0.005% of S, 0.001 to 0.01% of N, 0.001 to 0.05% of Nb, 0.001 to 0.05% of Ti, 0.001 to 0.005% of B, with a remainder of Fe and other inevitable impurities, satisfying Relational Expression 1 below, and having a microstructure including, by area, 5 to 15% of austenite, 80% or more of auto-tempered martensite, and a remainder of at least one of bainite and ferrite,
(
10
[
C
]
+
[
S
i
]
+
2
.
5
[
M
n
]
)
/
(
1.
5
[
C
r
]
+
2
.
0
[
M
o
]
-
3
.
2
[
N
b
]
)
≤
20.
[
Relational
Expression
1
]
2 . A hot-rolled steel sheet comprising, by weight:
0.06 to 0.12% of C, 0.004 to 0.4% of Si,0.8 to 2.0% of Mn, 0.01 to 0.05% of Al, 0.05 to 1.0% of Cr, 0.001 to 0.3% of Mo, 0.001 to 0.05% of P, 0.001 to 0.005% of S, 0.001 to 0.01% of N, 0.001 to 0.05% of Nb, 0.001 to 0.05% of Ti, 0.001 to 0.005% of B, with a remainder of Fe and other inevitable impurities, satisfying Relational Expression 1 below, and having a microstructure including, by area, 80% or more of auto-tempered martensite, and a remainder of at least one of fresh martensite, bainite, and ferrite, wherein a wave height of the steel sheet in a longitudinal direction is 10 nm or less,
(
10
[
C
]
+
[
S
i
]
+
2
.
5
[
M
n
]
)
/
(
1.
5
[
C
r
]
+
2
.
0
[
M
o
]
-
3
.
2
[
N
b
]
)
≤
20.
[
Relational
Expression
1
]
3 . The hot-rolled steel sheet of claim 1 , wherein the inevitable impurities include 0.01% or less of Ni.
4 . The hot-rolled steel sheet of claim 1 , wherein the hot-rolled steel sheet has an average grain size of prior austenite of 10 to 30 μm.
5 . The hot-rolled steel sheet of claim 2 , wherein the inevitable impurities include 0.01% or less of Ni.
6 - 7 . (canceled)
8 . The hot-rolled steel sheet of claim 2 , wherein the hot-rolled steel sheet has an average grain size of prior austenite of 10 to 30 μm.
9 . The hot-rolled steel sheet of claim 2 , wherein the hot-rolled steel sheet has a yield strength of 900 MPa or more.Join the waitlist — get patent alerts
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