US2008302450A1PendingUtilityA1
Object Comprising a Steel Part of Metal Construction Consisting of an Area Welded by a High Power Density Beam and Exhibiting an Excellent Toughness in a Molten Area, Method for Producing Said Object
Est. expiryJul 5, 2024(expired)· nominal 20-yr term from priority
Inventors:Dominique Kaplan
C22C 38/22B23K 15/0046C21D 9/50C21D 2211/002C21D 2211/008C22C 38/02C22C 38/04B23K 26/32B23K 2103/04B23K 2103/50
46
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Claims
Abstract
The invention discloses an object comprising at least one part made of steel, the composition of which comprises, the contents being expressed by weight, carbon with a content of between 0.005 and 0.27%, manganese between 0.5 and 1.6%, silicon between 0.1 and 0.4%, chromium in a content of less than 2.5%, Mo in a content of less than 1%, optionally one or more elements chosen from nickel, copper, aluminum, niobium, vanadium, titanium, boron, zirconium and nitrogen, the balance being iron and impurities resulting from the smelting, said steel part including at least one zone welded by a high-energy-density beam, characterized in that said welded zone has a microstructure consisting of 60 to 75% self-tempered martensite and, to complement this, 40 to 25% lower bainite, and preferably 60 to 70% self-tempered martensite and, to complement this, 40 to 30% lower bainite.
Claims
exact text as granted — not AI-modified1 - 10 . (canceled)
11 . An object comprising at least one part made of steel, the composition of which comprises, the contents being expressed by weight, carbon with a content of between 0.005 and 0.27%, manganese between 0.5 and 1.6%, silicon between 0.1 and 0.4%, chromium in a content of less than 2.5%, Mo in a content of less than 1%, optionally one or more elements selected from the group consisting of nickel, copper, aluminum, niobium, vanadium, titanium, boron, zirconium and nitrogen, the balance being iron and impurities resulting from the smelting, said steel part including at least one zone melted by a high-energy-density beam, wherein said melted zone has a microstructure consisting of 60 to 75% self-tempered martensite and, to complement this, 40 to 25% lower bainite.
12 . The object as claimed in claim 11 , wherein the object is a steel pipe comprising at least one portion having a zone welded in the longitudinal or transverse direction.
13 . The object as claimed in claim 11 , wherein the object consists of at least two hot-rolled or hot-forged plates of steel having the same or different compositions, of the same or different thickness, which are welded together.
14 . The object as claimed in claim 11 , wherein said high-energy-density beam is a laser beam.
15 . The object as claimed in claim 11 , wherein said high-energy-density beam is an electron beam.
16 . A method of producing an object as claimed in claim 11 , wherein said method comprises:
providing an object comprising at least one part made of steel, the composition of which comprises, the contents being expressed by weight, carbon with a content of between 0.005 and 0.27%, manganese between 0.5 and 1.6%, silicon between 0.1 and 0.4%, chromium in a content of less than 2.5%, Mo in a content of less than 1%, optionally one or more elements being selected from the group consisting of nickel, copper, aluminum, niobium, vanadium, titanium, boron, zirconium and nitrogen, the balance being iron and impurities resulting from the smelting; welding, by a high-energy-density process, said steel part to a steel workpiece of the same or different composition, which may or may not already form part of said object; the nitrogen content of the welding-melted zone does not exceed 0.020% and the welding power, the welding speed and the possible preheating, post-heating or cooling means are chosen in such a way that said melted zone cools according to a parameter
(
Δ
t
800
500
)
such that:
Δ
t
B
exp
-
0.75
ln
(
Δ
tB
/
Δ
tM
)
≤
(
Δ
t
800
500
)
≤
Δ
t
B
exp
-
0.6
ln
(
Δ
tB
/
Δ
tM
)
(
Δ
t
800
500
)
expressed in seconds denoting the time that elapses between the temperature of 800° C. and the temperature of 500° C. during the cooling after welding of said welded zone,
with: Δt B =exp (6.2 CE II+0.74)
Δt M =exp (10.6 CE I−4.8)
CE I =C+Mn/6+Si/24+Mo/4+Ni/12+Cu/15+(Cr(1−0.16√{square root over (Cr)})/8)+ f ( B )
CE II =C+Mn/3.6+Cu/20+Ni/9+Cr/5+Mo/4,
with: f ( B )=0, if B≦0.0001%
f ( B )=(0.03−1.5 N ) if 0.0001%<B≦0.00025%
f ( B )=(0.06−3 N ) if 0.00025%<B<0.0004%
f ( B )=(0.09−4.5 N ) if B≧0.0004%,
C, Mn, Si, Mo, Ni, Cu, Cr, B and N denote, respectively, the carbon, manganese, silicon, molybdenum, nickel, copper, chromium, boron and nitrogen contents, expressed as percentages by weight, of said melted zone.
17 . The method as claimed in claim 16 , wherein said welding is carried out homogeneously and autogenously by a laser beam, in that the nitrogen content of said steel does not exceed 0.020% and that the welding power, the welding speed and the possible preheating, post-heating or cooling means are chosen in such a way that said melted zone cools according to a parameter
(
Δ
t
800
500
)
such that:
Δ
t
B
exp
-
0.75
ln
(
Δ
tB
/
Δ
tM
)
≤
(
Δ
t
800
500
)
≤
Δ
t
B
exp
-
0.6
ln
(
Δ
tB
/
Δ
tM
)
(
Δ
t
800
500
)
,
expressed in seconds, denoting the time that elapses between the temperature of 800° C. and the temperature of 500° C. during the cooling after welding of said melted zone,
with: Δt B =exp (6.2 CE II+0.74)
Δt M =exp (10.6 CE I−4.8)
CE I =C+Mn/6+Si/24+Mo/4+Ni/12+Cu/15+(Cr(1−0.16√{square root over (Cr)})/8)+ f ( B )
CE II =C+Mn/3.6+Cu/20+Ni/9+Cr/5+Mo/4,
with: f ( B )=0, if B≦0.0001%
f ( B )=(0.03−1.5 N ) if 0.0001%<B≦0.00025%
f ( B )=(0.06−3 N ) if 0.00025%<B<0.0004%
f ( B )=(0.09−4.5 N ) if B≧0.0004%,
C, Mn, Si, Mo, Ni, Cu, Cr, B and N denote, respectively, the carbon, manganese, silicon, molybdenum, nickel, copper, chromium, boron and nitrogen contents, expressed as percentages by weight, of the welded steel.
18 . The method as claimed in claim 16 , wherein said welding is carried out autogeneously and homogeneously by an electron beam, in that the nitrogen content of said steel does not exceed 0.022% and that the welding power, the welding speed and the possible preheating, post-heating or cooling means are chosen in such a way that said zone melted by the electron beam cools according to a parameter
(
Δ
t
800
500
)
such that:
Δ
t
B
exp
-
0.75
ln
(
Δ
tB
/
Δ
tM
)
≤
(
Δ
t
800
500
)
≤
Δ
t
B
exp
-
0.6
ln
(
Δ
tB
/
Δ
tM
)
(
Δ
t
800
500
)
,
expressed in seconds, denoting the time that elapses between the temperature of 800° C. and the temperature of 500° C. during the cooling after welding of said melted zone,
with: Δt B =exp (6.2 CE II+0.74)
Δt M =exp (10.6 CE I−4.8)
CE I =C+Mn/6.67+Si/24+Mo/4+Ni/12+Cu/15+(Cr(1−0.16√{square root over (Cr)})/8)+ f ( B )
CE II =C+Mn/4+Cu/20+Ni/9+Cr/5+Mo/4,
with: f ( B )=0, if B≦0.0001%
f ( B )=(0.03−1.35 N ) if 0.0001%<B≦0.00025%
f ( B )=(0.06−2.7 N ) if 0.00025%<B<0.0004%
f ( B )=(0.09−4.05 N ) if B≧0.0004%,
C, Mn, Si, Mo, Ni, Cu, Cr, B and N denote, respectively, the carbon, manganese, silicon, molybdenum, nickel, copper, chromium, boron and nitrogen contents, expressed as percentages by weight, of the welded steel.
19 . The method of production as claimed in claim 16 , wherein said steel part is welded to a steel workpiece having the same or different composition, of the same or different thickness, which may or may not form part of said object, using a metal filler product.
20 . The object as claimed in claim 11 wherein the melted zone has a microstructure consisting of 60 to 70% self-tempered martensite and to complement this, 40 to 30% lower bainite.
21 . The method as claimed in claim 16 wherein the parameter Δt800/500 is described according to the following:
Δ
t
B
exp
-
0.7
ln
(
Δ
tB
/
Δ
tM
)
≤
(
Δ
t
800
500
)
≤
Δ
t
B
exp
-
0.6
ln
(
Δ
tB
/
Δ
tM
)
22 . The method as claimed in claim 17 wherein the parameter Δt800/500 is described according to the following:
Δ
t
B
exp
-
0.7
ln
(
Δ
tB
/
Δ
tM
)
≤
(
Δ
t
800
500
)
≤
Δ
t
B
exp
-
0.6
ln
(
Δ
tB
/
Δ
tM
)
23 . The method as claimed in claim 18 wherein the parameter Δt800/500 is described according to the following:
Δ
t
B
exp
-
0.7
ln
(
Δ
tB
/
Δ
tM
)
≤
(
Δ
t
800
500
)
≤
Δ
t
B
exp
-
0.6
ln
(
Δ
tB
/
Δ
tM
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