US2024417834A1PendingUtilityA1
Ferritic stainless steel and manufacturing method therefor
Est. expiryOct 26, 2041(~15.2 yrs left)· nominal 20-yr term from priority
C21D 8/02C22C 38/002C22C 38/001C21D 8/0247C21D 6/002C22C 38/06C22C 38/04C22C 38/02C21D 9/46C21D 8/0273C21D 8/0263C21D 8/0236C21D 8/0226C21D 6/004C21D 2211/005C23G 1/02B21C 47/02C22C 38/40
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Claims
Abstract
Disclosed in the present specification are: a ferritic stainless steel having improved elongation even if batch annealing is omitted; and a manufacturing method therefor. A ferritic stainless steel according to one embodiment of the present invention may comprise, by wt %, 0.01-0.1% of C, 0.01-1.0% of Si, 0.01-1.5% of Mn, P in an amount greater than 0% and less than or equal to 0.05%, S in an amount greater than 0% and less than or equal to 0.005%, 13.0-18.0% of Cr, 0.005-0.1% of N, 0.005-0.2% of Al, 0.05-0.25% of Ni, and the balance of Fe (iron) and other inevitable impurities.
Claims
exact text as granted — not AI-modified1 . A ferritic stainless steel comprising:
in percent by weight (wt %), 0.01 to 0.1% of C, 0.01 to 1.0% of Si, 0.01 to 1.5% of Mn, more than 0 to 0.05% of P, more than 0 to 0.005% of S, 13.0 to 18.0% of Cr, 0.005 to 0.1% of N, 0.005 to 0.2% of Al, 0.05 to 0.25% of Ni, the remaindered Fe (iron) and other unavoidable impurities, wherein an Ac1 value defined in equation 1 below is at least 920 and less than 990:
Ac
1
=
36
*
[
Cr
]
+
90
*
[
Si
]
+
760
*
[
Al
]
+
350
-
(
800
*
[
C
]
+
1300
*
[
N
]
+
150
*
[
Ni
]
+
50
*
[
Mn
]
)
Equation
1
(wherein in equation 1, [Cr], [Si], [Al], [C], [N], [Ni], and [Mn] refer to contents (wt %) of the respective elements).
2 . The ferritic stainless steel of claim 1 , wherein an elongation rate is at least 27%.
3 . A method of manufacturing a ferritic stainless steel comprising:
manufacturing a slab including, in percent by weight (wt %), 0.01 to 0.1% of C, 0.01 to 1.0% of Si, 0.01 to 1.5% of Mn, more than 0 to 0.05% of P, more than 0 to 0.005% of S, 13.0 to 18.0% of Cr, 0.005 to 0.1% of N, 0.005 to 0.2% of Al, 0.05 to 0.25% of Ni, the remaindered Fe (iron) and other unavoidable impurities, wherein an Ac1 value defined in equation 1 below is at least 920 and less than 990; reheating the slab; manufacturing a hot-rolled steel material by hot-rolling and coiling the reheated slab; obtaining a hot-rolled and wound hot-rolled sheet by hot-rolled-sheet-annealing the hot-rolled steel material at a hot-rolled sheet annealing heat treatment temperature T (HRA, ° C.) which satisfies equation (2) below, followed by cooling and winding; manufacturing a cold-rolled sheet by cold-rolling the hot-rolled and wound hot-rolled sheet; and cold-rolled-sheet-annealing the cold-rolled sheet at a cold-rolled sheet annealing heat treatment temperature T (CRA,° C.) which satisfies equation (3) below, followed by cooling and winding:
Ac
1
=
36
*
[
Cr
]
+
90
*
[
Si
]
+
760
*
[
Al
]
+
350
-
(
800
*
[
C
]
+
1300
*
[
N
]
+
150
*
[
Ni
]
+
50
*
[
Mn
]
)
Equation
1
(wherein in equation 1, [Cr], [Si], [Al], [C], [N], [Ni], and [Mn] refer to contents (wt %) of the respective elements).
840
≤
T
(
HRA
,
°C
)
≤
Ac
1
-
20
Equation
2
870
≤
T
(
CRA
,
°C
)
≤
Ac
1
-
20.
Equation
3
4 . The method of claim 3 , wherein the reheating is performed at 1100 to 1250° C.
5 . The method of claim 3 , wherein the hot-rolling is performed at a finish rolling completion temperature of 800 to 950° C.
6 . The method of claim 3 , wherein the coiling is performed at 750 to 850° C.
7 . The method of claim 3 , wherein the hot-rolled sheet annealing and the cold-rolled sheet annealing are performed for 30 seconds to 10 minutes.
8 . The method of claim 3 , wherein the cooling after the hot-rolled sheet annealing and the cooling after the cold-rolled sheet annealing are performed at a cooling rate of 50° C./s.
9 . The method of claim 3 , wherein the cold rolling is performed with a reduction rate of 60 to 90%.Join the waitlist — get patent alerts
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