US2024254588A1PendingUtilityA1
Wire rod having excellent drawability, and manufacturing method therefor
Est. expiryJun 18, 2041(~14.9 yrs left)· nominal 20-yr term from priority
C21D 8/06C21D 7/13C21D 2211/004C22C 38/001C21D 2211/009C21D 2211/003C22C 38/18C22C 38/06C22C 38/04C22C 38/02B21C 47/02B21B 1/16C21D 8/0226C21D 9/52C21D 9/525C21D 8/065
61
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Claims
Abstract
The present invention relates to a machine structure wire rod, which is applicable to vehicles, construction components and the like, and a manufacturing method therefor, and to a wire rod having excellent drawability, and a method for manufacturing same.
Claims
exact text as granted — not AI-modified1 . A wire rod having excellent drawability including by weight %:
C: 0.8 to 1.2%, Si: 0.01 to 0.6%, Mn: 0.1 to 0.6%, Cr: 0.8 to 2.0%, Al: 0.01 to 0.06%, N: 0.02% or less (excluding 0), with a balance of Fe and inevitable impurities, wherein a microstructure includes a pearlite main structure and proeutectoid cementite, and includes at least 20 AlN particles with an average particle diameter of 30 nm or less per unit area (μm 2 ), and the following Relational Expression 1 is satisfied,
[
Relational
Expression
1
]
(
Average
block
grain
size
(
μ
m
)
)
2
/
Proeutectite
cementite
length
(
μ
m
/
1200
μ
m
2
)
)
≤
0.5
2 . The wire rod having excellent drawability of claim 1 , wherein the proeutectoid cementite is formed at grain boundaries along prior austenite grains, and is formed in a network shape.
3 . The wire rod having excellent drawability of claim 1 , wherein the microstructure comprises, by area fraction: 10% or less of proeutectoid cementite and a balance of pearlite.
4 . The wire rod having excellent drawability of claim 1 , wherein the wire rod has a tensile strength of 1200 MPa or more and a cross-sectional reduction rate of 20% or more.
5 . The wire rod having excellent drawability of claim 1 wherein the wire rod is not subjected to a spheroidization softening heat treatment before a drawing process, and is drawn by at least 15% during wire drawing.
6 . The wire rod having excellent drawability of claim 1 , wherein the wire rod has an average aspect ratio of cementite of 3 or less after the wire drawing and spheroidization heat treatment.
7 . A method for manufacturing a wire rod having excellent drawability, comprising:
heating a steel slab, including by weight: C: 0.8 to 1.2%, Si: 0.01 to 0.6%, Mn: 0.1 to 0.6%, Cr: 0.8 to 2.0%, Al: 0.01 to 0.06%, N: 0.02% or less (excluding 0), with a balance of Fe and other inevitable impurities, and performing rolling on the steel slab to prepare a billet; cooling the prepared billet; heating the billet to a temperature of 950 to 1050° C.; wire rolling the heated billet to a prepare a wire rod; and winding the wire rod, cooling the wire rod at an average cooling rate of 3° C./sec or more to 550 to 650° C., and cooling the same at an average cooling rate of 1° C./sec or less to a temperature of 550° C. to 650° C. or less, wherein the wire rolling is performed so that an austenite grain size (AGS) is 5 to 20 μm before finish rolling, and the finish rolling is performed at a temperature range of 730° C. to Acm and a deformation amount of 0.3 or more.
8 . The method for manufacturing a wire rod having excellent drawability of claim 7 , wherein the hot rolling is performed to satisfy the condition of Relational Expression (2) below,
[
Relational
Expression
2
]
2500
*
(
[
C
]
-
1
)
2
+
100000
*
(
[
A
1
]
-
0.035
)
2
+
(
AGS
-
12.5
)
4
/
130
+
(
Finish
rolling
temperature
-
760
)
2
/
65
≤
80
in the above Relational Expression (2), [C] and [Al] refer to an alloy composition C and Al content (% by weight), a unit of AGS is μm, and a unit of finish rolling temperature is ° C.
9 . The method for manufacturing a wire rod having excellent drawability of claim 7 , wherein the billet is heated to a temperature within a range of 1100 to 1300° C. for 2 to 10 hours, and the billet having a temperature of 500° C. or more at a cooling rate of 5° C./s or more after the billet is rolled.
10 . The method for manufacturing a wire rod having excellent drawability of claim 7 , wherein the billet heating time is 80 to 120 minutes.Cited by (0)
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