US2024254610A1PendingUtilityA1
Hot-Formed Steel Part and Manufacturing Method
Est. expiryJun 2, 2041(~14.9 yrs left)· nominal 20-yr term from priority
C22C 38/60C22C 38/54C22C 38/50C22C 38/48C22C 38/46C22C 38/44C22C 38/42C22C 38/06C22C 38/02C22C 38/002C22C 38/001C21D 2211/009C21D 2211/008C21D 2211/005C21D 2211/002C21D 2211/001C21D 1/30C21D 1/20C21D 1/10C21D 7/08C21D 8/0236C21D 8/0226C22C 38/32C22C 38/38C22C 38/58C22C 38/28
33
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Claims
Abstract
The invention relates to a hot-formed steel part having a composition consisting of 0.22%≤C≤0.35%, 0.50%≤Mn≤1.70%; 0.50%≤Cr≤1.70%; traces≤Mo≤0.15%; traces≤Si≤0.40%; traces≤Ni≤0.50%; traces≤Cu≤0.50%; traces≤V≤0.08%; traces≤Al≤0.10%; 0.001%≤B≤0.010%; 0.01%≤Ti≤0.06%; traces≤Nb≤0.05%; traces≤S≤0.15%; traces≤Ca≤0.010%; traces≤Te≤0.030%; traces≤Se≤0.050%; traces≤Bi≤0.050%; traces≤Pb≤0.100%; traces≤P≤0.100%; traces≤N≤0.013%; with 540≤(830−270*C %−90*Mn %−70*Cr %−83*Mo %−37*Ni %)≤600 and Ti %≥2.5N %. The microstructure consists of at least 70% bainitic ferrite and carbides or residual austenite, the residual austenite fraction being at most 10%, at most 30% martensite and/or proeutectoid ferrite and/or pearlite, the proeutectoid ferrite and/or pearlite fraction being at most 10%.
Claims
exact text as granted — not AI-modified1 - 16 . (canceled)
17 . A hot-formed steel part, wherein the steel has a composition that consists of the following, expressed in percentages by weight
0.22
%
≤
C
≤
0.35
%
;
0.5
%
≤
Mn
≤
1.7
%
;
0.5
%
≤
Cr
≤
1.7
%
;
traces
≤
Mo
≤
0.15
%
;
traces
≤
Si
≤
0.4
%
;
traces
≤
Ni
≤
0.5
%
;
traces
≤
Cu
≤
0.5
%
;
traces
≤
V
≤
0.08
%
;
traces
≤
Al
≤
0.1
%
;
0.001
%
≤
B
≤
0.
010
%
;
0.01
%
≤
Ti
≤
0.06
%
;
traces
≤
Nb
≤
0.05
%
;
traces
≤
S
≤
0.15
%
;
traces
≤
Ca
≤
0.01
%
;
traces
≤
Te
≤
0.03
%
;
traces
≤
Se
≤
0.05
%
;
traces
≤
Bi
≤
0.05
%
;
traces
≤
Pb
≤
0.1
%
;
traces
≤
P
≤
0.1
%
;
traces
≤
N
≤
0.013
%
;
with the remainder being iron and impurities resulting from the elaboration; and
wherein the steel has the following compositional relations:
540
≤
(
830
-
270
*
C
%
-
90
*
Mn
%
-
70
*
Cr
%
-
83
*
Mo
%
-
37
*
Ni
%
)
≤
600
;
and
Ti
%
≥
2.5
N
%
wherein the steel has a microstructure that consists of, in surface fractions:
at least 70% of a mixture of bainitic ferrite and carbides or residual austenite, the residual austenite fraction being less than or equal to 10%, the mixture of bainitic ferrite and carbides or residual austenite forming bainite, the bainite including the morphologies of bainite or bainite ferrite called acicular ferrite or intragranular bainite; and
no more than 30% of martensite, pro-eutectoid ferrite, and/or pearlite, the pro-eutectoid ferrite and/or pearlite fraction being less than or equal to 10%.
18 . The hot-formed steel part of claim 17 , wherein the residual austenite fraction is less than or equal to 5%.
19 . The hot-formed steel part of claim 17 , wherein the concentration of carbon in the composition of the steel is 0.25%<C≤0.30%.
20 . The hot-formed steel part of claim 17 , wherein the concentration of manganese in the composition of the steel is 1.10%≤Mn≤1.70%.
21 . The hot-formed steel part of claim 17 , wherein the concentration of molybdenum in the composition of the steel is trace≤Mo≤0.10%.
22 . The hot-formed steel part of claim 17 , wherein the concentration of silicon in the composition of the steel is trace≤Si≤0.15%.
23 . The hot-formed steel part of claim 17 , wherein the concentration of nickel in the composition of the steel is trace≤Ni≤0.35%.
24 . The hot-formed steel part of claim 17 , wherein the concentration of copper in the composition of the steel is trace≤Cu≤0.30%.
25 . The hot-formed steel part of claim 17 , wherein the concentration of vanadium in the composition of the steel is trace≤V≤0.05%.
26 . The hot-formed steel part of claim 17 , wherein the steel as a relation that is 560<(830−270 C %−90 Mn %−70 Cr %−83 Mo %−37 Ni %)≤600.
27 . A method of manufacturing a steel part, the method comprising:
hot-forming a steel semi-finished product in the austenitic phase and having a composition consisting of the following, expressed in percentages by weight:
0.22
%
≤
C
≤
0.35
%
;
0.5
%
≤
Mn
≤
1.7
%
;
0.5
%
≤
Cr
≤
1.7
%
;
traces
≤
Mo
≤
0.15
%
;
traces
≤
Si
≤
0.4
%
;
traces
≤
Ni
≤
0.5
%
;
traces
≤
Cu
≤
0.5
%
;
traces
≤
V
≤
0.08
%
;
traces
≤
Al
≤
0.1
%
;
0.001
%
≤
B
≤
0.
010
%
;
0.01
%
≤
Ti
≤
0.06
%
;
traces
≤
Nb
≤
0.05
%
;
traces
≤
S
≤
0.15
%
;
traces
≤
Ca
≤
0.01
%
;
traces
≤
Te
≤
0.03
%
;
traces
≤
Se
≤
0.05
%
;
traces
≤
Bi
≤
0.05
%
;
traces
≤
Pb
≤
0.1
%
;
traces
≤
P
≤
0.1
%
;
traces
≤
N
≤
0.013
%
;
the remainder being iron and impurities resulting from the elaboration; and
wherein the steel has the following compositional relations:
540
≤
(
830
-
270
*
C
%
-
90
*
Mn
%
-
70
*
Cr
%
-
83
*
Mo
%
-
37
*
Ni
%
)
≤
600
;
and
Ti
%
≥
2.5
N
%
;
and
cooling the hot-formed semi-finished product with still air, in forced air, under a hood, or in a container, wherein between 750° C. and 550° C. the product is cooled at a rate that is greater than or equal to 0.15° C./s, between 550° ° C. and 250° C. the product is cooled at a rate that is between 0.1 and 0.5° C./s, and below 250° C. the product is cooled at a rate that is between 0.1 and 100° C./s.
28 . The method of claim 27 further comprising machining or cold-forming the semi-finished product before the hot-forming step.
29 . The method of claim 27 further comprising cold machining or cold-forming the hot-formed semi-finished product after the cooling step.
30 . The method according to claim 27 further comprising subjecting at least part of the hot-formed semi-finished product to a surface treatment by high-frequency induction.
31 . The method according to claim 30 further comprising, after carrying out the surface treatment by high-frequency induction, tempering the hot-formed semi-finished product at a temperature between 150° C. and 350° C.
32 . The method according to claim 27 further comprising work hardening at least a part of the hot-formed semi-finished product.Join the waitlist — get patent alerts
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