US 2026/0233344 A1Published application

Submerged arc welding method and method of producing welded joint

AssigneeJfe Steel Corporation

InventorsAtsushi TAKADA, Takatoshi OKABE, Masaharu KOMURA

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Abstract

Provided is a submerged arc welding method capable of producing a welded joint that is free of welding defects and satisfies requirements for yield stress, tensile strength, and toughness, even when carrying out submerged arc welding of a 780 MPa grade steel with a heat input of 300 kJ/cm or more. In the submerged arc welding method, a welding wire to be used has a specified composition, and CeqW (Expression 1) calculated from the composition is defied to be 0.40 to 0.80. Further, a flux to be used has a specified composition, and α (Expression 2) calculated from the composition is defied to be 0.35 to 0.70. CeqW = [ C ] W + [ Si ] W / 24 + [ Mn ] W / 6 + [ Ni ] W / 40 + [ Cr ] W / 5 + [ Mo ] W / 4 ( 1 ) α = ( 0 . 3 - [ Fe ] F / 200 ) × { [ Si ] F / 24 + [ Mn ] F / 6 + [ Ni ] F / 40 + [ Cr ] F / 5 + [ Mo ] F / 4 } + 0.4 × CeqW ( 2 )

Claims7

Dependent claims

A submerged arc welding method, the method comprising welding a 780 MPa grade steel with a welding heat input of 300 kJ/cm or more using a welding wire and a flux, wherein

the welding wire comprises a chemical composition containing, in mass %,
C:
0.03% to 0.12%,
Si:
0.01% to 0.60%,
Mn:
1.0% to 2.0%,
P:
0.015% or less,
S:
0.015% or less,
Ni:
1.0% to 4.0%,
Cr:
1.5% or less,
Mo:
0.2% to 1.2%,
O:
0.015% or less,
N:
0.010% or less, and
optionally, at least one selected from the group consisting of:
Cu:
1.0% or less,
Al:
0.20% or less,
Ti:
0.20% or less,
Nb:
0.10% or less,
V:
0.10% or less,
Ca:
0.010% or less,
B:
0.010% or less, and
REM:
0.020% or less,
with the balance being Fe and inevitable impurity,
wherein CeqW represented by the following Expression (1) is in a range from 0.40 to 0.80,
the flux comprises a chemical composition containing, in mass %,
SiO2:
5% to 30%,
CaO:
1% to 10%,
MgO:
5% to 30%,
Al2O3:
3% to 20%,
TiO2:
2% to 20%,
Na2O:
1% to 3%,
CaF2:
2% to 20%,
one or more metal carbonates:
2% to 12% in total in CO2 content equivalent,
Si:
0.10% to 2.50%,
Mn:
0.1% to 2.0%,
Ni:
1.0% to 12.0%,
Cr:
8.0% or less,
Mo:
1.0% to 8.0%,
Fe:
10% to 30%, and
optionally, at least one selected from the group consisting of:
B2O3:
1.0% or less,
K2O:
3.0% or less,
Ti:
1.00% or less, and
Al:
1.00% or less,
wherein α represented by the following Expression (2) is in a range from 0.35 to 0.70,
CeqW
=
[
C
]
W
+
[
Si
]
W
/
24
+
[
Mn
]
W
/
6
+
[
Ni
]
W
/
40
+
[
Cr
]
W
/
5
+
[
Mo
]
W
/
4
(
1
)
α
=
(
0
.
3
-
[
Fe
]
F
/
200
)
×
{
[
Si
]
F
/
24
+
[
Mn
]
F
/
6
+
[
Ni
]
F
/
40
+
[
Cr
]
F
/
5
+
[
Mo
]
F
/
4
}
+
0.4
×
CeqW
(
2
)
where [element]W of the wire in Expression (1) or [component]F of the flux in Expression (2) represents the content in mass % of the element or component, and is set to 0 when the element or component is not contained.

179 more elements

Dependencies are inferred from the claim text.