CN117241914A - Flux-cored wire and method for manufacturing welded joint - Google Patents

Flux-cored wire and method for manufacturing welded joint Download PDF

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Publication number
CN117241914A
CN117241914A CN202280032387.1A CN202280032387A CN117241914A CN 117241914 A CN117241914 A CN 117241914A CN 202280032387 A CN202280032387 A CN 202280032387A CN 117241914 A CN117241914 A CN 117241914A
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Prior art keywords
flux
oxide
total
content
cored wire
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松尾孟
加茂孝浩
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Nippon Steel Corp
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Nippon Steel and Sumitomo Metal Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
    • B23K35/368—Selection of non-metallic compositions of core materials either alone or conjoint with selection of soldering or welding materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
    • B23K35/0255—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in welding
    • B23K35/0261—Rods, electrodes, wires
    • B23K35/0266—Rods, electrodes, wires flux-cored
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24—Selection of soldering or welding materials proper
    • B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24—Selection of soldering or welding materials proper
    • B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
    • B23K35/3053—Fe as the principal constituent
    • B23K35/3073—Fe as the principal constituent with Mn as next major constituent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Nonmetallic Welding Materials (AREA)

Abstract

A flux-cored wire comprising a steel sheath and a flux filled therein, comprising C:0.02 to 0.8 percent of Si:0.2 to 0.8 percent of Mn: 15-30%, ni: 1-10%, N:0.05 to 1%, prescribed amounts of other optional elements, the remainder: fe and impurities, total Ti oxides, total Si oxides, total Zr oxides, total Al oxides, K 2 SiF 6 、K 2 ZrF 6 、NaF、Na 3 AlF 6 、CaF 2 MgF (MgF) 2 Fluoride of (a), na oxide, naF and Na 3 AlF 6 Total of Na-containing compounds, K oxide, K 2 SiF 6 K is as follows 2 ZrF 6 The total of K-containing compounds in (2) is a predetermined amount.

Description

Flux-cored wire and method for manufacturing welded joint
Technical Field
The present disclosure relates to flux-cored wires (flux-filled wires) and methods of manufacturing welded joints.
Background
In recent years, due to the strengthening of carbon dioxide emission restrictions based on global warming, the demand for hydrogen fuel without carbon dioxide emission and natural gas with less carbon dioxide emission as compared with petroleum, coal, and the like has been increasing, and along with this, the demand for liquid hydrogen tanks and LNG tank construction has also been increasing in the world. For steel materials used for liquid hydrogen storage tanks and LNG storage tanks, ni-based low temperature steel containing 6 to 9% Ni is used in view of the requirement of ensuring toughness at an extremely low temperature of-196 ℃.
In addition, for welding these Ni-based low-temperature steels, an austenitic flux-cored wire that can obtain a weld metal having excellent low-temperature toughness is used. The flux-cored wire is designed to have Ni content of mainly 70%.
For example, patent document 1 discloses a flux-cored wire having a Ni content of 70%: a flux-cored wire comprising 35 to 70% Ni and, in the flux, at least 4.0% by mass of TiO based on the total mass of the wire 2 、SiO 2 ZrO (ZrO) 2 Furthermore, mnO 2 The conversion meter contains 0.6 to 1.2 mass% of Mn oxide, and when TiO is used 2 、SiO 2 、ZrO 2 MnO and MnO 2 The content of (converted amount) was set to [ TiO ] in mass% respectively 2 ]、[SiO 2 ]、[ZrO 2 ][ MnO ] 2 ]In the process, the catalyst is prepared by [ TiO ] 2 ]/[ZrO 2 ]Is 2.3 to 3.3, [ SiO ] 2 ]/[ZrO 2 ]0.9 to 1.5, and ([ TiO ] s 2 ]+[SiO 2 ]+[ZrO 2 ])/[MnO 2 ]A Ni-based alloy of 5 to 13 as a sheath).
Further, patent document 2 discloses that: "a flux-cored wire for tubular flux-cored arc welding comprising, in weight%, C:0.15 to 0.8 percent of Si:0.2 to 1.2 percent of Mn: 15-34%, cr: less than 6% and Mo: 1.5-4%, S: less than 0.02%, P: less than 0.02%, B: less than 0.01%, ti: 0.09-0.5%, N:0.001 to 0.3 percent of TiO 2 :4 to 15 percent of SiO 2 、ZrO 2 Al and Al 2 O 3 Aggregate of more than 1 kind of:0.01 to 9%, and 1 or more kinds selected from K, na and Li: 0.5 to 1.7 percent, more than 1 of F and Ca: 0.2 to 1.5 percent, and the balance of Fe and other unavoidable impurities.
Patent document 1: japanese patent laid-open No. 2008-246507
Patent document 2: japanese patent application laid-open No. 2017-502842
Disclosure of Invention
Problems to be solved by the invention
However, a welding wire designed to have a Ni content of 70% for ensuring low-temperature toughness of molten metal is very expensive, and an inexpensive welding wire is required.
Expensive Ni is well known as an austenite stabilizing element, but inexpensive Mn also has the same effect. Therefore, if the Ni content is reduced and the Mn content is increased, a weld metal excellent in low-temperature toughness can be obtained at low cost. However, when the Mn amount is increased by simply replacing Ni with Mn, the low-temperature toughness is lowered due to excessive Mn.
Accordingly, an object of the present invention is to provide a flux-cored wire that can inexpensively obtain a weld metal having excellent low-temperature toughness, and a method for producing a welded joint using the flux-cored wire.
Means for solving the problems
The means for solving the problems include the following means.
<1> a flux-cored wire for welding comprising a steel sheath and a flux filled in the steel sheath,
the metal components in the chemical composition of the flux-cored wire are as follows, in mass% relative to the total mass of the flux-cored wire:
C：0.020～0.800％、
Si：0.20～0.80％、
Mn：15.0～30.0％、
P：0～0.050％、
S：0～0.050％、
Cu：0～10.0％、
Ni：1.0～10.0％、
Cr：0～2.0％、
Mo：0～10.0％、
Nb：0～5.0％、
V：0～5.0％、
W：0～10.0％、
Mg：0～1.00％、
Al：0～3.0％、
Ca：0～0.100％、
Ti：0～3.000％、
B：0～0.1000％、
REM：0～0.100％、
Bi：0～0.050％、
N：0.050～1.000％、
O:0 to 0.020%, and
the remainder: fe and impurities are mixed with each other,
the oxides and fluorides in the chemical composition of the flux-cored wire are, in mass% relative to the total mass of the flux-cored wire:
TiO of Ti oxide 2 The total of the converted values is 3.00 to 8.00 percent,
SiO of Si oxide 2 The total of the converted values is 0.10 to 1.00%,
ZrO of Zr oxide 2 The total of the converted values is 0 to 0.80%,
al of Al oxide 2 O 3 The total of the converted values is 0 to 0.80%,
containing K 2 SiF 6 、K 2 ZrF 6 、NaF、Na 3 AlF 6 、CaF 2 MgF (MgF) 2 Any one of 1 or more specific fluorides, the total of which is 0.10 to 2.00%,
contains Na oxide, naF and Na 3 AlF 6 Any one or more of Na-containing compounds, which are total (wherein Na oxide is Na 2 O conversion value) of 0.01 to 2.00%,
contains K oxide, K 2 SiF 6 K is as follows 2 ZrF 6 Any one or more of K-containing compounds, which add up (wherein K oxide is K 2 O conversion value)0.01 to 2.00 percent.
<2> the flux-cored wire according to <1>, wherein the total content of Mg, al and Ca in the metal component is 0.01% or more by mass% with respect to the total mass of the flux-cored wire.
<3> the flux-cored wire of <1> or <2>, wherein the content of Si in the metal component is Si:0.25 to 0.80 percent.
The flux-cored wire of any one of <1> to <3>, wherein a mass ratio (Mn/Ni) of the Mn content to the Ni content in the metal component is 1.20 or more.
The flux-cored wire of any one of <1> to <4>, wherein the X value calculated by the following formula A is 0.10 to 160.00.
X＝(8×CaF 2 +5×MgF 2 +5×NaF+5×K 2 SiF 6 +5×K 2 ZrF 6 +Na 3 AlF 6 )/(SiO 2 +Al 2 O 3 +ZrO 2 +0.5×MgO+CaO+0.5×Na 2 O+0.5×K 2 O+MnO 2 +FeO) type A
In formula A, caF 2 、MgF 2 、NaF、K 2 SiF 6 、K 2 ZrF 6 Na and Na 3 AlF 6 The content of the compound represented by each chemical formula is calculated as mass% relative to the total mass of the flux-cored wire. Furthermore, siO 2 SiO representing Si oxide 2 Total of converted values, al 2 O 3 Al representing Al oxide 2 O 3 Sum of converted values, zrO 2 ZrO representing Zr oxide 2 The sum of converted values, mgO represents the sum of MgO converted values of Mg oxides, caO represents the sum of CaO converted values of Ca oxides, na 2 O represents Na of Na oxide 2 Total of O converted values, K 2 O represents K of K oxide 2 Total of O conversion values, mnO 2 MnO representing Mn oxide 2 The total of the converted values, feO, represents the total of the FeO converted values of the Fe oxide.
Furthermore, in formula ASiO as described above 2 Conversion value of Al as described above 2 O 3 Converted value, the above ZrO 2 Conversion value, mgO conversion value, caO conversion value, na conversion value 2 O conversion value, K as described above 2 O conversion value, mnO as described above 2 The converted value and the FeO converted value are expressed as mass% relative to the total mass of the flux-cored wire.
<6>According to<1>～<5>The flux-cored wire of any one of claims, comprising Mg oxide and MgF 2 Any one of the Mg-containing compounds of 1 or more of the above compounds has a total (wherein Mg oxide is a MgO conversion value) of 0.01 to 2.00%.
The flux-cored wire of any one of <1> to <6>, wherein the steel sheath does not have a welded portion at a joint.
The flux-cored wire of any one of <1> to <6>, wherein the steel sheath has a welded portion at a joint.
<9> the flux-cored wire of any one of <1> to <8>, which is coated with one or both of polytetrafluoroethylene oil and perfluoropolyether oil on the surface.
<10> a method for producing a welded joint, comprising the step of welding a steel material using the flux-cored wire of any one of <1> to <9 >.
Effects of the invention
According to the present disclosure, a flux-cored wire that can inexpensively obtain a weld metal excellent in low-temperature toughness and a method for manufacturing a welded joint using the flux-cored wire can be provided.
Drawings
Fig. 1 is a cross-sectional view showing a state of a bead shape of a bead when fillet welding is performed on 2 steel plates in the example.
Detailed Description
An embodiment as an example of the present disclosure will be described.
In the present specification, the term "numerical range represented by" to "refers to a range including these numerical values as a lower limit value and an upper limit value, when the numerical values described before and after" to "are not" exceeding "and" falling below ". The numerical range in which the numerical values described before and after the "to" are "exceeded" or "fallen below" means a range not including these numerical values as a lower limit value or an upper limit value.
In the numerical ranges described in the present specification in stages, the upper limit of a numerical range in a stage may be replaced with the upper limit of a numerical range described in another stage, or may be replaced with a value shown in the examples. The lower limit of the numerical range in a certain stage may be replaced with the lower limit of the numerical range described in another stage, or may be replaced with the value shown in the example.
In addition, "%" means "% by mass" with respect to the content.
As the content (%), the terms "0" to "mean that the component is an optional component, and may be not contained.
< flux-cored wire >
The flux-cored wire (hereinafter, sometimes simply referred to as "wire") of the present disclosure includes a steel sheath (hereinafter, sometimes simply referred to as "sheath") and a flux filled in the steel sheath.
In the flux-cored wire of the present disclosure, the metal component in the chemical composition of the flux-cored wire is a predetermined composition, and the oxides and fluorides in the chemical composition of the flux-cored wire contain Ti oxide, si oxide, fluoride, na-containing compound, K-containing compound in a predetermined amount, do not contain Zr oxide, al oxide, or contain Zr oxide, al oxide in a predetermined amount.
The flux-cored wire of the present disclosure is configured as described above, and thus a welding wire that can inexpensively obtain a weld metal excellent in low-temperature toughness can be obtained.
Moreover, the flux-cored wire of the present disclosure was found through the following knowledge.
The inventors have studied a technique for obtaining a welding wire which improves the low-temperature toughness of a weld metal even when the Ni content is reduced and the Mn content is increased. As a result, the following knowledge was obtained.
Expensive Ni is known as an austenite stabilizing element, but low-cost Mn also has the same effect, and if the Mn content is increased, the Ni content can be reduced, and an inexpensive welding wire can be obtained, and a weld metal excellent in low-temperature toughness can be obtained. However, when the Mn amount is increased by simply replacing Ni with Mn, the oxygen amount in the weld metal increases due to excessive Mn, and instead the low-temperature toughness decreases. This is because: mn is easily combined with oxygen to form oxides in the weld metal.
In contrast, by increasing the Mn content and simultaneously containing specific fluorides such as NaF and MgF, which are components that achieve strong deoxidization and reduce hydrogen, the oxygen content in the weld metal can be reduced, and low-temperature toughness can be ensured.
From the above knowledge, it was found that: the flux-cored wire of the present disclosure is a wire that can inexpensively obtain a weld metal excellent in low-temperature toughness.
The reasons for limiting the elements (elements including optional elements) constituting the flux-cored wire of the present disclosure will be specifically described below.
[ Metal component in chemical composition of flux-cored wire ]
Hereinafter, the metal components in the chemical composition of the flux-cored wire of the present disclosure will be described.
In the description of the metal components of the flux-cored wire, "%" means "% by mass relative to the total mass of the flux-cored wire" unless otherwise specified.
The metal component of the flux-cored wire may be contained in the steel sheath or may be contained in the flux.
Further, when the flux-cored wire of the present disclosure has a coating layer on the outer surface of the steel sheath, it may also be contained in the coating layer.
The term "metal component in chemical composition" of the flux-cored wire refers to a component other than oxide, fluoride, nitride, and metal carbonate, among components contained in the flux-cored wire. In addition, since oxides, fluorides, nitrides, and metal carbonates present in the steel skin are not contained or contained in an extremely small amount, they are not removed at the time of measurement. That is, the above-mentioned "components other than oxides, fluorides, nitrides, and metal carbonates" means components other than oxides, fluorides, nitrides, and metal carbonates contained in the flux.
The metal components in the chemical composition of the flux-cored wire disclosed by the disclosure are as follows:
C：0.020～0.800％、
Si：0.20～0.80％、
Mn：15.0～30.0％、
P：0～0.050％、
S：0～0.050％、
Cu：0～10.0％、
Ni：1.0～10.0％、
Cr：0～2.0％、
Mo：0～10.0％、
Nb：0～5.0％、
V：0～5.0％、
W：0～10.0％、
Mg：0～1.00％、
Al：0～3.0％、
Ca：0～0.100％、
Ti：0～3.000％、
B：0～0.1000％、
REM：0～0.100％、
Bi：0～0.050％、
N：0.050～1.000％、
o:0 to 0.020%, and
the remainder: fe and impurities.
That is, in the flux-cored wire of the present disclosure, the above-described components are the contents of the components contained in addition to the oxides, fluorides, nitrides, and metal carbonates.
(C：0.020～0.800％)
C is an element for improving the strength of the weld metal, and is an element for securing the strength of the weld metal.
On the other hand, if the C content of the welding wire is excessive, the influence of deterioration of toughness due to an increase in strength of the weld metal is very large, and the low-temperature toughness of the weld metal is remarkably lowered.
Thus, the C content of the welding wire is set to 0.020 to 0.800%.
The lower limit of the C content of the welding wire is preferably 0.050%, 0.100%, or 0.200%.
The upper limit of the C content of the welding wire is preferably 0.750%, 0.700%, 0%, 0.650%, 0.600%, 0.550%, 0.500%, 0.450%, 0.400% or 0.350%.
(Si：0.20～0.80％)
Si improves the cleanliness of the weld metal and suppresses the occurrence of weld defects such as pinholes.
On the other hand, if the Si content of the welding wire is excessive, micro segregation is likely to occur in the weld metal during welding of Ni steel or Ni-based alloy steel, and significant embrittlement occurs in the segregated portion.
Thus, the Si content of the wire is set to 0.20 to 0.80%.
The lower limit of the Si content of the welding wire is preferably 0.25%, 0.30% or 0.35%.
The upper limit of the Si content of the welding wire is preferably 0.75%, 0.70% or 0.65%.
(Mn：15.0～30.0％)
Mn is an austenite stabilizing element. If the Mn content of the welding wire is too low, austenitization of the weld metal becomes difficult to proceed and the low temperature toughness deteriorates.
Mn is an element that functions as a deoxidizer to improve the cleanliness of the weld metal. Further, mn is an element that makes S in the weld metal harmless by forming MnS and improves the low-temperature toughness of the weld metal. In addition, mn also has an effect of preventing high temperature cracking.
On the other hand, if the Mn content of the welding wire is excessive, micro segregation is likely to occur in the weld metal during welding of Ni steel or Ni-based alloy steel, and significant embrittlement occurs in the segregated portion. Further, the amount of oxygen in the weld metal increases due to an excessive amount of Mn, and conversely, the low temperature toughness decreases.
Thus, the Mn content of the welding wire is set to 15.0 to 30.0%.
The lower limit of the Mn content of the welding wire is preferably 17.0%, 18.0%, 19.0% or 20.0%.
The upper limit of the Mn content of the welding wire is preferably 28.0%, 25.0%, 22.0% or 20.0%.
(P：0～0.050％)
Since P is an impurity element and decreases toughness of the weld metal, the P content of the welding wire is preferably reduced as much as possible. Thus, the lower limit of the P content of the welding wire is set to 0%. However, from the viewpoint of reduction of the depuration cost, the content of P in the welding wire is preferably 0.003% or more.
On the other hand, if the P content of the welding wire is 0.050% or less, the range is within which adverse effects of P on toughness can be tolerated. In order to effectively suppress the decrease in toughness of the weld metal, the P content of the wire is preferably 0.040% or less, 0.030% or less, 0.020% or less, 0.015% or less, or 0.010% or less.
(S：0～0.050％)
S is an impurity element, and the toughness of the weld metal is reduced, so that the S content of the welding wire is preferably reduced as much as possible. Thus, the lower limit of the S content of the welding wire is set to 0%. However, from the viewpoint of reduction of the S removal cost, the S content of the welding wire is preferably 0.003% or more.
On the other hand, if the S content of the welding wire is 0.050% or less, the S content falls within a range that can tolerate the adverse effect of S on toughness. In order to effectively suppress the decrease in toughness of the weld metal, the S content of the welding wire is preferably 0.040% or less, 0.030% or less, 0.020% or less, 0.015% or less, or 0.010% or less.
(Cu：0～10.0％)
Cu is a precipitation strengthening element, and may be contained in the wire in order to improve the strength of the weld metal. Cu is an austenite stabilizing element, and may be contained in the wire in order to improve the low-temperature toughness of the weld metal.
On the other hand, if the Cu content of the wire is excessive, the above-described effect is saturated.
Thus, the Cu content of the wire is set to 0 to 10.0%.
The lower limit of the Cu content of the wire is preferably 0.1%, 0.3%, 0.5%, 0.7% or 1.0%.
The upper limit of the Cu content of the wire is preferably 9.5%, 9.0% or 8.0%.
(Ni：1.0～10.0％)
Ni is an austenite stabilizing element. If the Ni content of the welding wire is too low, austenitization of the weld metal becomes difficult to proceed and the low-temperature toughness deteriorates. In addition, in order to secure low temperature toughness of the weld metal, it is necessary to excessively increase the Ni content of the steel sheath.
On the other hand, if the Ni content of the welding wire is increased, the cost of the welding wire becomes high.
Thus, the Ni content of the welding wire is set to 1.0 to 10.0%.
The lower limit of the Ni content of the welding wire is preferably 1.5%, 2.0% or 2.5%.
The upper limit of the Ni content of the welding wire is preferably 9.5%, 9.0% or 8.5%.
(Cr：0～2.0％)
Cr is an austenite stabilizing element, and may be contained in the wire in order to improve the low-temperature toughness of the weld metal.
On the other hand, if the Cr content of the welding wire is excessive, the amount of the low melting point compound in the molten metal increases, and further the solid-liquid coexisting temperature range of the molten metal becomes wider, so that high temperature cracking becomes easily caused.
Thus, the Cr content of the welding wire is set to 0 to 2.0%.
The lower limit of the Cr content of the welding wire is preferably 0.1%, 0.2% or 0.3%.
The upper limit of the Cr content of the welding wire is preferably 1.9%, 1.8% or 1.7%.
(Mo：0～10.0％)
Mo is a solid solution strengthening element and a precipitation strengthening element, and may be contained in the welding wire in order to improve the strength of the weld metal.
On the other hand, if the Mo content of the welding wire is excessive, the strength of the weld metal becomes excessive and the low temperature toughness decreases.
Thus, the Mo content of the welding wire is set to 0 to 10.0%.
The lower limit of the Mo content of the welding wire is preferably 2.0%, 2.5%, 3.0% or 3.5%.
The upper limit of the Mo content of the welding wire is preferably 9.8%, 9.5%, 9.0% or 8.0%.
(Nb：0～5.0％)
Nb is an element that forms carbide in the weld metal and increases the strength of the weld metal, and thus may be contained in the wire.
On the other hand, if the Nb content of the welding wire is excessive, there is a possibility that high temperature cracking of the weld metal may occur.
Thus, the Nb content of the welding wire is set to 0 to 5.0%.
The lower limit of the Nb content of the wire is preferably 0.5%, 1.0% or 1.5%.
The upper limit of the Nb content of the wire is preferably 4.5%, 4.0% or 3.5%.
(V：0～5.0％)
V is an element that forms carbonitrides in the weld metal and increases the strength of the weld metal, and thus may be contained in the wire.
On the other hand, if the V content of the welding wire is excessive, there is a possibility that high temperature cracking of the weld metal may occur.
Thus, the V content of the welding wire is set to 0 to 5.0%.
The lower limit of the V content of the welding wire is preferably 0.5%, 1.0% or 1.5%.
The upper limit of the V content of the welding wire is preferably 4.5%, 4.0% or 3.5%.
(W：0～10.0％)
W is a solid solution strengthening element, and may be contained in a wire in order to improve the strength of a weld metal.
On the other hand, if the W content of the welding wire is excessive, the strength of the weld metal becomes excessive, and there is a possibility that the toughness is lowered.
Thus, the W content of the welding wire is set to 0 to 10.0%.
The lower limit of the W content of the welding wire is preferably 0.5%, 1.0% or 2.0%.
The upper limit of the W content of the welding wire is preferably 9.0%, 8.0%, 7.0% or 6.0%.
(Mg：0～1.00％)
Mg is a deoxidizing element, reduces oxygen in the weld metal, and has an effect of improving toughness of the weld metal, and thus may be contained in the wire.
On the other hand, if the Mg content of the wire is excessive, the arc is unstable, spatter and blowholes increase, and the welding workability deteriorates.
Thus, the Mg content of the welding wire is set to 0 to 1.00%.
The lower limit of the Mg content of the welding wire is preferably 0.02%, 0.05%, 0.10% or 0.20%.
The upper limit of the Mg content of the welding wire is preferably 0.90%, 0.80% or 0.70%.
(Al：0～3.0％)
Al is a deoxidizing element, and has an effect of suppressing the occurrence of welding defects such as pinholes and improving the cleanliness of the weld metal, and thus may be contained in the wire.
On the other hand, if the Al content of the welding wire is excessive, al forms nitride or oxide in the weld metal, which may lower the low temperature toughness of the weld metal.
Thus, the Al content of the wire is set to 0 to 3.0%.
The lower limit of the Al content of the welding wire is preferably 0.05%, 0.1%, 0.5% or 1.0%.
The upper limit of the Al content of the welding wire is preferably 2.5%, 2.0% or 1.5%.
(Ca：0～0.100％)
Ca has an effect of changing the structure of sulfide in the weld metal and further miniaturizing the sulfide and oxide in the weld metal, and is therefore effective for improving the ductility and toughness of the weld metal. Therefore, ca may be contained in the wire.
On the other hand, if the Ca content of the welding wire is excessive, coarsening of sulfides and oxides may occur, resulting in deterioration of the low-temperature toughness of the weld metal. Further, the weld bead shape may be degraded, and the welding performance may be degraded due to the instability of the arc.
Thus, the Ca content of the wire is set to 0 to 0.100%.
The lower limit of the Ca content of the welding wire is preferably 0.010%, 0.020% or 0.030%.
The upper limit of the Ca content of the welding wire is preferably 0.095%, 0.090% or 0.085%.
(the total content of Mg, al and Ca is 0.01% or more)
Mg, al and Ca are preferably contained in the wire because they are effective for arc stability.
Therefore, the total content of Mg, al, and Ca in the welding wire is preferably set to 0.01% or more.
The lower limit of the total content of Mg, al and Ca in the wire is preferably 0.03%, 0.10% or 0.30%.
The total content of Mg, al, and Ca in the welding wire means metal Mg, metal Al, and metal Ca contained in the steel sheath and the flux. From the viewpoint of arc stability, the total content of metal Mg, metal Al, and metal Ca contained in the flux is preferably set to 0.01% or more. The lower limit of the total content of Mg, al and Ca in the flux is preferably 0.10%, 0.30% or 0.50%.
(Ti：0～3.000％)
Ti is a deoxidizing element and has an effect of suppressing the occurrence of welding defects such as pinholes and improving the cleanliness, and thus may be contained in the wire.
On the other hand, if the Ti content of the welding wire is excessive, carbide is generated in the weld metal, and there is a possibility that toughness of the weld metal may be deteriorated.
Thus, the Ti content of the welding wire is set to 0 to 3.000%.
The lower limit of the Ti content of the welding wire is preferably 0.020%, 0.050% or 0.100%.
The upper limit of the Ti content of the welding wire is preferably 2.500%, 2.000% or 1.500%.
(B：0～0.1000％)
B has an effect of improving hardenability of the weld metal and further improving tensile strength of the weld metal, and thus may be contained in the wire.
On the other hand, if the B content of the welding wire is excessive, B in the weld metal is alsoBecomes excessive to form coarse BN or Fe 23 (C、B) 6 And B compound, which may deteriorate the low-temperature toughness of the weld metal.
Thus, the B content of the welding wire is set to 0 to 0.1000%.
The lower limit of the B content of the welding wire is preferably 0.0010%, 0.0020% or 0.0030%.
The upper limit of the B content of the welding wire is preferably 0.0900%, 0.0700% or 0.0500%.
(REM：0～0.100％)
REM is an element that stabilizes the arc, and thus may be contained in the wire.
On the other hand, if the REM content of the welding wire is excessive, spatter becomes severe, and there is a possibility that the welding operation becomes poor.
Thus, the REM content of the welding wire is set to 0 to 0.100%.
The lower limit of the REM content of the welding wire is preferably 0.001%, 0.002% or 0.005%.
The upper limit of the REM content of the welding wire is preferably 0.090%, 0.080% or 0.070%.
"REM" means 17 elements in total including Sc, Y and lanthanoid, and "REM content" means the total content of these 17 elements. In the case of using lanthanoid as REM, REM is industrially contained in the form of a misch metal alloy.
(Bi：0～0.050％)
Bi is an element that improves the slag detachability, and therefore may be contained in the wire.
On the other hand, if the Bi content of the welding wire is excessive, solidification cracking may occur in the weld metal.
Accordingly, the Bi content of the welding wire is set to 0 to 0.050%.
The lower limit of the Bi content of the welding wire is preferably 0.005%, 0.010% or 0.020%.
The upper limit of the Bi content of the welding wire is preferably 0.048%, 0.045%, 0.040% or 0.035%.
(N：0.050～1.000％)
N is an austenite stabilizing element and is also an invasive solid solution strengthening element. N is an element that has less adverse effect on toughness of the weld metal than C due to an increase in strength of the weld metal.
If the N content of the wire is small, austenitization of the weld metal becomes difficult to proceed, and the low-temperature toughness of the weld metal deteriorates. In addition, the strength of the weld metal is also insufficient.
On the other hand, if the N content of the welding wire is excessive, the occurrence of the fusing increases, and causes welding defects.
Thus, the N content of the welding wire is set to 0.050 to 1.000%.
The lower limit of the N content of the welding wire is preferably 0.070%, 0.100%, or 0.150%.
The upper limit of the N content of the welding wire is preferably 0.950%, 0.900% or 0.850%.
(O：0～0.020％)
O may be contained as an impurity in the metal component of the welding wire. However, if the O content becomes excessive, deterioration of toughness and ductility in the weld metal occurs, and therefore the upper limit of the O content of the welding wire is set to 0.020% or less.
The upper limit of the O content of the welding wire is preferably 0.015%, 0.010% or 0.005%.
On the other hand, the lower limit of the O content of the welding wire is preferably 0.0005%, 0.001% or 0.002% from the viewpoint of suppressing an increase in manufacturing cost due to a decrease in the O content.
Here, the O content refers to the amount of oxygen contained in the metal component of the welding wire, and for example, refers to the amount of oxygen contained in an oxide film or the like as the alloy powder. Therefore, oxygen contained as an oxide in the wire is excluded.
(remainder: fe and impurities)
The other residual components in the metal component of the welding wire are Fe and impurities.
The remaining Fe is, for example, fe contained in the steel sheath, fe (for example, iron powder) contained in the alloy powder contained in the flux, or the like.
The impurities are components derived from raw materials or mixed in by various factors in the manufacturing process when the welding wire is industrially manufactured, and are allowable components within a range that does not adversely affect the welding wire.
(mass ratio of Mn content to Ni content (Mn/Ni))
Mn and Ni are austenite stabilizing elements, respectively, so that the low-temperature toughness of the weld metal is improved. On the other hand, ni is an expensive metal, and Mn is an element that causes an increase in smoke generation amount.
Therefore, from the viewpoint of suppressing the cost of the wire and improving the low-temperature toughness of the weld metal, the mass ratio (Mn/Ni) of the Mn content to the Ni content in the wire is preferably 1.20 or more.
The lower limit of the mass ratio (Mn/Ni) of Mn content to Ni content in the wire is more preferably 1.50 or 1.80.
The upper limit of the mass ratio (Mn/Ni) of Mn content to Ni content in the wire is preferably 28.0 or 25.0.
[ oxides and fluorides in the chemical composition of flux-cored wire ]
Next, oxides, fluorides, and the like in the chemical composition of the flux-cored wire of the present disclosure will be described.
In the description of oxides, fluorides, and the like of the flux-cored wire, "%" means "% by mass relative to the total mass of the flux-cored wire" unless otherwise specified.
The oxides, fluorides, nitrides and metal carbonates present in the steel skin are not contained or contained in very small amounts. Therefore, in the present specification, when the contents of oxides, fluorides, nitrides, and metal carbonates are mentioned, the contents of oxides, fluorides, nitrides, and metal carbonates contained in the flux are referred to.
(TiO of Ti oxide) 2 Summation of converted values: 3.00 to 8.00 percent of mass percent
Ti oxide increases the oxygen content of the weld metal and deteriorates low temperature toughness.
On the other hand, ti oxide is a slag component, and has an effect of uniformly coating the entire weld bead with slag. In addition, ti oxide has an effect of stabilizing the arc and reducing the amount of spatter generated. Therefore, if Ti oxide is contained, the weldability (particularly, vertical weldability) improves.
TiO if Ti oxide 2 If the total of the converted values is less than 3.00%, the amount of slag generated is insufficient and the weld bead cannot be uniformly covered, so that the slag sinters on the weld bead surface and the weld bead appearance becomes poor. In addition, if TiO of Ti oxide 2 When the total of the converted values is less than 3.00%, the effect of stabilizing the arc is lost, and the amount of spatter generated increases. Further, the welding workability (in particular, the vertical weldability) cannot be ensured.
On the other hand, if TiO of Ti oxide 2 If the total of the converted values exceeds 8.00%, the oxygen content of the weld metal increases, and low-temperature toughness cannot be ensured. In addition, if TiO of Ti oxide 2 When the total of the converted values exceeds 8.00%, the amount of spatter generated is reduced due to arc stabilization, but as the viscosity of slag increases, the slag becomes thicker, and the edge portion of the weld bead becomes a bulged shape. In addition, if TiO of Ti oxide 2 When the total of the converted values exceeds 8.00%, pits (pit) are easily generated. In addition, slag inclusion is generated.
Thus, tiO of Ti oxide 2 The total of the converted values is set to 3.00 to 8.00%.
TiO of Ti oxide 2 The lower limit of the total of the converted values is preferably 3.50%, 4.00% or 4.50%.
TiO of Ti oxide 2 The upper limit of the total of the converted values is preferably 7.50%, 7.00% or 6.50%.
The Ti oxide mainly exists in the form of rutile, titanium oxide, titanium slag, electropolished alumina product, sodium titanate, potassium titanate, and the like in the flux. Therefore, by mainly controlling the Ti oxide content of the flux, the Ti oxide content can be set to the above range.
Here, tiO of Ti oxide 2 The sum of the converted values is obtained by adding up all Ti oxides (such as TiO, tiO 2 、Ti 2 O 3 、Ti 3 O 5 Etc., added in the form of rutile, titanium oxide, titanium slag, electropolished alumina product, sodium titanate, potassium titanate, etc.), to TiO 2 TiO in the case of (2) 2 Mass% relative to the total mass of the welding wire.
Further, tiO of Ti oxide 2 The total of the converted values is obtained as follows: the mass of Ti present as an oxide in the wire was analyzed using a fluorescent X-ray analyzer and an X-ray diffraction (XRD) device. Further, the amount of Ti present as an oxide in the welding wire and the amount of Ti contained as a metal component can be obtained separately by analyzing the molecular structure of the component contained in the flux by X-ray diffraction (XRD) in addition to analyzing the component contained in the flux by fluorescence X-ray analysis.
Specifically, first, flux is collected from a wire, and the flux is analyzed by the above method. For example, if TiO is detected by analysis 2 、Ti 2 O 3 、Ti 3 O 5 In the case of (C), the mass% of each Ti oxide is represented by [ TiO ] 2 ]、[Ti 2 O 3 ]、[Ti 3 O 5 ]TiO representing and containing Ti oxide 2 The sum of the converted values is calculated as [ converted TiO ] 2 ]In the expression, the calculation is performed by the following expression C1.
Converted TiO 2 ]＝(0.60×[TiO 2 ]+0.67×[Ti 2 O 3 ]+0.64×[Ti 3 O 5 ]) X 1.67C 1
The coefficients (0.60, 0.67, 0.64) in the formula C1 are coefficients for calculating the amounts of Ti contained in the respective oxides, and the last multiplier (1.67) is a coefficient for calculating TiO from the total amount of Ti present as an oxide in the wire 2 And converting the multiplier of the value.
Here, a method of obtaining coefficients will be described. If it is set to detect M x O y (e.g., tiO) 2 、Ti 2 O 3 、Ti 3 O 5 ) And (3) oxides of M x O y The coefficient is calculated by the following formula C2.
[ atomic weight of M element ] ×x/([ atomic weight of M element ] ×x+ [ atomic weight of oxygen ] ×y) formula C2
The coefficients of 0.60, 0.67, and 0.64 in the formula C1 correspond to the coefficients obtained by the formula C2.
A method for calculating the multiplier of the converted value will be described. For conversion to M a O b (e.g., tiO) 2 ) The multiplier of (2) is calculated by the following formula C3.
([ atomic weight of M element ] ×a+ [ atomic weight of oxygen ] ×b)/([ atomic weight of M element ] ×a) formula C3
1.67 in the formula C1 corresponds to the multiplier obtained by the formula C3.
Further, it is also considered that the oxide is a compound formed by combining 2 kinds of metal elements. Regarding the determination of the coefficient in this case, if M is detected x O y M 2 z (e.g., tiO) 3 Fe, i.e. m=ti, M 2 The following formula C4 calculates the oxides of =fe, x=1, y=3, and z=1.
Atomic weight of M element]X/([ atomic weight of M element)]X x+ [ atomic weight of oxygen ]]×y+[M 2 Atomic weight of element]X z) C4
Furthermore, siO of Si oxide 2 ZrO of converted values of total Zr oxide 2 Total of converted values, al of Al oxide 2 O 3 Total of converted values, total of MgO converted values of Mg oxide, na of Na oxide 2 Total of O conversion values, K of K oxide 2 Total of O conversion values, total of CaO conversion values of Ca oxide, mnO of Mn oxide 2 The sum of converted values and the sum of FeO converted values of Fe oxide also pass through TiO with Ti oxide 2 The sum of the converted values is obtained by the same calculation. That is, the collected flux is analyzed by a fluorescent X-ray analyzer and an X-ray diffraction (XRD) device, and the coefficients and multipliers are calculated according to the above formulas C2, C3, and C4 in accordance with the detected various oxides, and are calculated in the same manner as the above formula C1.
Representative oxides detected by the analysis are listed below.
Si oxygenChemical compound: siO, siO 2 、Si 2 O 3 、Si 2 O 4
Zr oxide: zrO (ZrO) 2
Al oxide: alO, al 2 O 3 、Al 3 O 5
Mg oxide: mgO, mgO 2 、Mg 2 O
Na oxide: na (Na) 2 O、Na 2 O 2
K oxide: k (K) 2 O、KO 2
Ca oxide: caO, caO 2
Mn oxide: mnO, mn 2 O、MnO 2
Fe oxide: feO, fe 2 O 4 、FeO 3
In addition, in the analysis of various compositions such as Ti oxide, a method of separating the steel sheath from the flux is as follows. The steel sheath of the flux-cored wire is opened using pliers or the like, and the flux therein is collected. The attached flux is removed from the inner surface of the steel sheath, which is the contact portion between the steel sheath and the flux, by using a wire brush, ultrasonic washing, or the like. Thereby, the steel sheath is separated from the flux.
(SiO of Si oxide) 2 Summation of converted values: 0.10 to 1.00 percent by mass percent)
The Si oxide increases the oxygen content of the weld metal, and deteriorates low-temperature toughness.
On the other hand, si oxide is a slag component, and has an effect of improving the viscosity of molten slag and improving slag removability.
SiO of Si oxide 2 When the total of the converted values is less than 0.10%, the slag coating state is poor, the slag removability becomes poor, and the weld bead shape and the weld bead appearance also become poor. Further, the welding workability (in particular, the vertical weldability) cannot be ensured.
On the other hand, if SiO of Si oxide 2 If the total of the converted values exceeds 1.00%, the oxygen content of the weld metal increases, and low-temperature toughness cannot be ensured. Furthermore, if SiO of Si oxide 2 Conversion toWhen the total value exceeds 1.00%, the amount of spatter generated increases. Furthermore, if SiO of Si oxide 2 When the total of the converted values exceeds 1.00%, pits, air pockets, and the like are easily generated. In addition, slag inclusion is generated.
Thus, siO of Si oxide 2 The total of the converted values is set to 0.10 to 1.00%.
SiO of Si oxide 2 The lower limit of the total of the converted values is preferably 0.15%, 0.20% or 0.25%.
SiO of Si oxide 2 The upper limit of the total of the converted values is preferably 0.95%, 0.90% or 0.85%.
The Si oxide is mainly present in the form of silica sand, zircon sand, feldspar, sodium silicate, potassium silicate, and the like in the flux. Therefore, the content of Si oxide in the flux is mainly controlled, and thus the content range of Si oxide can be set.
(ZrO of Zr oxide) 2 Summation of converted values: 0 to 0.80 percent by mass percent)
Zr oxide increases the oxygen content of the weld metal, and deteriorates low-temperature toughness. Accordingly, zr oxide-free ZrO is preferable from the viewpoint of low-temperature toughness 2 The lower limit of the total of the converted values is set to 0%.
However, zr oxide is a slag component, and has an effect of improving slag coating property and smoothing a bead shape in horizontal fillet welding, and thus may be contained from such a viewpoint.
On the other hand, if ZrO of Zr oxide 2 When the total of the converted values exceeds 0.80%, the bead shape tends to be convex. In addition, slag inclusion is generated.
Thus, zrO of Zr oxide 2 The total of the converted values is set to 0 to 0.80%.
ZrO of Zr oxide 2 The upper limit of the total of the converted values is preferably 0.60%, 0.40%, 0.20% or 0.10%.
The Zr oxide is mainly present in the form of zircon sand, zirconia, or the like in the flux, and may be contained in a trace amount in the Ti oxide. Therefore, the Zr oxide content of the flux can be set to a range of the Zr oxide content by mainly controlling the Zr oxide content.
(Al of Al oxide) 2 O 3 Summation of converted values: 0 to 0.80 percent by mass percent)
Since Al oxide serves as an oxygen source, if Al oxide is added, the amount of oxygen in the weld metal increases, and this becomes a factor of deterioration in toughness. Therefore, from the viewpoint of low temperature toughness, al free of Al oxide is preferable 2 O 3 The lower limit of the total of the converted values is set to 0%.
However, al oxide can be contained from this point of view because it has an effect of preventing undercut on the upper leg side of the fillet bead by improving slag coating in the case of forming molten slag.
On the other hand, if Al of Al oxide 2 O 3 When the total of the converted values exceeds 0.80%, the bead edge portion on the lower leg side of the fillet bead has a bulged bead shape. In addition, slag inclusion is generated.
Thus, al of Al oxide 2 O 3 The total of the converted values is set to 0 to 0.80%.
Al of Al oxide 2 O 3 The upper limit of the total of the converted values is preferably 0.70%, 0.60%, 0.40%, 0.20% or 0.10%.
In many cases, the Al oxide is mainly present in the form of components such as alumina and feldspar in the flux. Therefore, the content of Al oxide in the flux is mainly controlled, and thus the content range of Al oxide can be set.
( Aggregate of specific fluorides: 0.10 to 2.00 percent of the weight percent )
K 2 SiF 6 、K 2 ZrF 6 、NaF、Na 3 AlF 6 、CaF 2 MgF (MgF) 2 (in this specification, these fluorides are referred to as "specific fluorides") have the effect of reducing the oxygen amount of the weld metal.
If the total amount of the specific fluorides is less than 0.10%, the oxygen content of the weld metal becomes high, and low-temperature toughness cannot be ensured in the welding wire of the present disclosure having a large Mn content.
On the other hand, if the total amount of the specific fluorides exceeds 2.00%, a large amount of welding fume is generated, and welding defects are generated.
Thus, the total amount of the specific fluoride is set to 0.10 to 2.00% by containing 1 or more kinds of the specific fluoride.
The total lower limit of the specific fluorides is preferably 0.20%, 0.30% or 0.40%.
The upper limit of the total of the specific fluorides is preferably 1.90%, 1.80% or 1.70%.
( Summation of Na-containing compounds: 0.01 to 2.00 percent of mass percent )
Na oxide, naF and Na 3 AlF 6 (hereinafter, these Na-containing compounds may be referred to as "specific Na-containing compounds") act as deoxidizers to reduce the oxygen content of the weld metal by decomposing Na during welding. Thereby, the low-temperature toughness of the molten metal is improved.
If the total of the specific Na-containing compounds is less than 0.01%, the effect of reducing the oxygen content of the weld metal is small, and the low-temperature toughness cannot be ensured.
On the other hand, if the total of the specific Na-containing compounds exceeds 2.00%, the solidification temperature of the welding slag is lowered, and the welding workability (in particular, vertical weldability) is deteriorated.
Accordingly, the total of Na-containing compounds containing at least 1 of the specific Na-containing compounds is set to 0.01 to 2.00%.
The total lower limit of the specific Na-containing compounds is preferably 0.05%, 0.15%, 0.20% or 0.30%.
The upper limit of the total of the specific Na-containing compounds is preferably 1.90%, 1.80%, 1.70% or 1.50%.
The content of Na oxide means Na of Na oxide 2 And (5) adding the converted values of O.
( Total of K-containing compounds: 0.01 to 2.00 percent of mass percent )
K oxide, K 2 SiF 6 K is as follows 2 ZrF 6 (hereinafter, these K-containing compounds may be referred to as "specific K-containing compounds") act as deoxidizers to reduce the oxygen content of the weld metal by decomposing K during welding. Thereby, the low-temperature toughness of the molten metal is improved.
If the total amount of the specific K-containing compounds is less than 0.01%, the effect of reducing the oxygen content of the weld metal is small, and low-temperature toughness cannot be ensured.
On the other hand, if the total amount of the specific K-containing compounds exceeds 2.00%, the solidification temperature of the welding slag is lowered, and the welding workability (in particular, vertical weldability) is deteriorated.
Accordingly, the total of K-containing compounds containing at least 1 of the specific K-containing compounds is set to 0.01 to 2.00%.
The total lower limit of the specific K-containing compounds is preferably 0.05%, 0.20%, 0.30% or 0.40%.
The upper limit of the total of the specific K-containing compounds is preferably 1.95%, 1.90%, 1.80% or 1.50%.
The content of K oxide refers to K of K oxide 2 And (5) adding the converted values of O.
( Summation of Mg-containing compounds: 0.01 to 2.00 percent of mass percent )
The flux-cored wire of the present embodiment may contain Mg oxide and MgF in addition to the specific Na-containing compound and the specific K-containing compound 2 Any one of the Mg-containing compounds of 1 or more.
Mg oxide and MgF 2 (hereinafter, these Mg-containing compounds may be referred to as "specific Mg-containing compounds") act as deoxidizers to reduce the oxygen content of the weld metal by decomposing Mg during welding. Thereby, the low-temperature toughness of the molten metal is improved.
If a specific Mg-containing compound is contained in the welding wire (preferably, the total of the specific Mg-containing compounds is 0.01% or more), the effect of reducing the oxygen content of the weld metal increases, and the low-temperature toughness increases.
On the other hand, if the total content of the specific Mg-containing compounds is 2.00% or less, the solidification temperature of the welding slag increases, and the welding workability (particularly, vertical weldability) improves.
Accordingly, the total content of Mg-containing compounds of any 1 or more of the specific Mg-containing compounds is preferably set to 0 to 2.00%, and in the case of containing Mg-containing compounds, the total content is preferably set to 0.01 to 2.00%.
The total lower limit of the specific Mg-containing compounds is more preferably 0.05%, 0.20%, 0.30% or 0.40%.
The upper limit of the total of the specific Mg-containing compounds is more preferably 1.90%, 1.80% or 1.70%.
The content of Mg oxide refers to the sum of MgO conversion values of Mg oxide.
(other meanings of specific Na-containing Compound and specific K-containing Compound contained in the welding wire)
The content of the specific Na-containing compound and the content of the specific K-containing compound are set to be less than 0.01%, respectively, even if CaF containing Ca functioning as a deoxidizer is increased 2 Spatter increases and the welding workability deteriorates. In addition, even if Mg metal functioning as a deoxidizer is added, mg metal increases the diffusible hydrogen amount of the weld metal, and the low-temperature cracking resistance is deteriorated.
Therefore, in order to obtain a weld metal excellent in welding workability (in particular, vertical weldability) and also excellent in low-temperature toughness and low-temperature cracking resistance, it is necessary to include a specific Na-containing compound and a specific K-containing compound in the above-described ranges, respectively, in the welding wire.
From the same point of view, it is also preferable to include a specific Mg-containing compound in the above range in the welding wire.
The content of the specific Na-containing compound, the specific K-containing compound, and the specific Mg-containing compound is the content in mass% with respect to the total mass of the flux-cored wire.
(X value calculated by A)
In the flux-cored wire of the present disclosure, the X value calculated by the following formula a is preferably 0.10 to 160.00.
X＝(8×CaF 2 +5×MgF 2 +5×NaF+5×K 2 SiF 6 +5×K 2 ZrF 6 +Na 3 AlF 6 )/(SiO 2 +Al 2 O 3 +ZrO 2 +0.5×MgO+CaO+0.5×Na 2 O+0.5×K 2 O+MnO 2 +FeO) type A
In formula A, caF 2 、MgF 2 、NaF、K 2 SiF 6 、K 2 ZrF 6 Na and Na 3 AlF 6 The content of the compound represented by each chemical formula is calculated as mass% relative to the total mass of the flux-cored wire. Furthermore, siO 2 SiO representing Si oxide 2 Total of converted values, al 2 O 3 Al representing Al oxide 2 O 3 Sum of converted values, zrO 2 ZrO representing Zr oxide 2 The sum of converted values, mgO represents the sum of MgO converted values of Mg oxides, caO represents the sum of CaO converted values of Ca oxides, na 2 O represents Na of Na oxide 2 Total of O converted values, K 2 O represents K of K oxide 2 Total of O conversion values, mnO 2 MnO representing Mn oxide 2 The total of the converted values, feO, represents the total of the FeO converted values of the Fe oxide. Furthermore, the above SiO in formula A 2 Conversion value of Al as described above 2 O 3 Converted value, the above ZrO 2 Conversion value, mgO conversion value, caO conversion value, na conversion value 2 O conversion value, K as described above 2 O conversion value, mnO as described above 2 The converted value and the FeO converted value are expressed as mass% relative to the total mass of the flux-cored wire.
In formula a, the molecule is an index that includes a component (Ca, mg, na, K, si) that decomposes during welding and functions as a deoxidizer to reduce the oxygen content of the weld metal and the amount of fluorine compound that reduces the diffusible hydrogen content of the weld metal.
On the other hand, the denominator is an index of the amount of compounds containing oxygen (O) that increases the oxygen amount of the weld metal.
That is, if the X value is 0.10 or more, the amount of the compound containing oxygen (O) that increases the oxygen amount of the weld metal is small, the oxygen amount reducing action of the weld metal becomes large, and the low-temperature toughness is improved.
On the other hand, if the X value is 160.00 or less, the amount of fluoride is not excessive, slag inclusion becomes difficult to occur, and a sound joint can be easily produced.
Accordingly, the value of X calculated by the formula a is preferably set to 0.10 to 160.00.
The lower limit of the X value is more preferably 1.00, 5.00 or 10.00.
The upper limit of the X value is more preferably 130.00, 100.00, 70.00, 50.00 or 20.00.
Total content of other oxides: 0 to 10.00 percent of
When the flux-cored wire of the present disclosure contains 1 or 2 or more oxides selected from the group consisting of Fe oxide, mg oxide, na oxide, K oxide, mn oxide, and Ca oxide as oxides other than Ti oxide, si oxide, zr oxide, and Al oxide, the total content thereof is preferably 10.00% or less. The oxides contained in the group consisting of Fe oxide, mg oxide, na oxide, K oxide, mn oxide, and Ca oxide are sometimes simply referred to as "other oxides". The total value of the contents of the respective oxides in the other oxides may be simply referred to as "total content of the other oxides".
In the case where the flux-cored wire of the present disclosure contains 1 or 2 or more of the above-mentioned other oxides, the total content of the above-mentioned other oxides is expressed as FeO conversion value of Fe oxide, mgO conversion value of Mg oxide, na of Na oxide 2 Conversion value of O and K of K oxide 2 MnO of oxide of Mn and O conversion value 2 The conversion value and the CaO conversion value of Ca oxide are obtained in total.
In the flux-cored wire of the present disclosure, the other oxides are not essential components, and thus the lower limit of the total content of the other oxides in the flux-cored wire is 0%.
On the other hand, other oxides have an effect of maintaining the shape of the weld bead well and an effect of improving the vertical weldability. Mg oxide, fe oxide, and the like have an effect of stabilizing an arc. In order to obtain the above-described effect, the total content of the other oxides may be set to more than 0%. In order to further exert these effects, the lower limit of the total content of other oxides may be set to 0.05%, 0.10%, 0.15% or 0.20%. On the other hand, if the total content of the other oxides is 10.00% or less, the occurrence of slag inclusion can be suppressed, and a sound joint can be easily produced. Therefore, the upper limit of the total content of the other oxides is preferably set to 10.00%, or may be set to 9.00%, 8.00%, 7.00%, 6.00%, 3.00%, 2.00%, 1.00%, 0.50% or 0.30%.
The content of other oxides in the flux-cored wire of the present disclosure need not be defined according to the kind of each oxide.
The content of each of the other oxides and the total content of the other oxides were measured by fluorescence X-ray analysis and X-ray diffraction (XRD) in the same manner as the content of the Ti oxide described above.
(nitride, metal carbonate)
Nitrides, particularly those in flux, have the effect of reducing the amount of diffusible hydrogen in the weld metal, significantly improving the low temperature cracking resistance of the weld metal. The reason for this is not clear, but one of the reasons is presumed to be: n in the nitride is combined with hydrogen (H) during welding to form ammonia (NH) 3 ) The NH is 3 Is discharged outside the weld metal.
Thus, the flux-cored wire of the present disclosure may also include nitrides.
In the flux-cored wire of the present disclosure, for example, a metal selected from AlN, BN, ca may be contained as the nitride 3 N 2 、CeN、CrN、Cu 3 N、Fe 4 N、Fe 3 N、Fe 2 N、Mg 3 N、Mo 2 N、NbN、Si 3 N 4 、TiN、VN、ZrN、Mn 2 N and Mn 4 1 or more than 2 of N.
The metal carbonate is ionized by an arc to produce CO 2 And (3) gas. CO 2 The gas reduces the hydrogen partial pressure in the welding atmosphere and reduces the amount of diffusible hydrogen in the weld metal.
Thus, the flux-cored wire of the present disclosure may also include metal carbonates in the flux.
In the flux-cored wire of the present disclosure, as the metal carbonate, for example, a metal selected from MgCO may be contained 3 、Na 2 CO 3 、LiCO 3 、CaCO 3 、K 2 CO 3 、BaCO 3 、FeCO 3 、MnCO 3 SrCO 3 1 or more than 2 of them.
However, the kind and composition of the metal carbonate are not limited.
The contents of the nitride and the metal carbonate were measured by fluorescence X-ray analysis and X-ray diffraction (XRD) in the same manner as the contents of the Ti oxide.
The flux-cored wire of the present disclosure may further include a lubricant applied to the surface of the wire. The lubricant applied to the surface of the wire has an effect of improving the feeding property of the wire during welding. As the lubricant for the welding wire, various kinds of lubricants (for example, vegetable oil such as palm oil) can be used, but in order to suppress low-temperature cracking of the welding metal, one or both of polytetrafluoroethylene oil (PTFE oil) and perfluoropolyether oil (PFPE oil) containing no H are preferably used. As described above, the flux-cored wire of the present disclosure may further include a plating layer formed on the surface of the wire. In this case, the lubricant is applied to the surface of the plating layer.
The amount of hydrogen contained in the flux-cored wire of the present disclosure is not particularly limited, but is preferably 12ppm or less relative to the total mass of the flux-cored wire in order to reduce the diffusible hydrogen amount of the weld metal. The amount of hydrogen in the flux-cored wire may increase due to moisture penetrating into the flux-cored wire during storage of the flux-cored wire. Therefore, in the case where the period from the production of the welding wire to the use of the welding wire is long, it is preferable to prevent the penetration of moisture by means described later.
(welding wire shape)
Next, the shape (wire structure) of the flux-cored wire of the present disclosure will be described.
Generally, flux-cored wires are distinguished as any of the following: a welding wire having a shape (seamless shape) without a slit-like gap (a welding wire having no welded portion at the seam of the steel sheath) because the seam of the steel sheath is welded; and a welding wire having a shape (seamed shape) including a slit-like gap (a welding wire having a welded portion at the seam of the steel sheath) because the seam of the steel sheath is not welded.
With the flux-cored wire of the present disclosure, any shape may be employed. However, in order to suppress occurrence of low-temperature cracking of the weld metal, it is preferable that the steel skin has no slit-like gap. H (hydrogen) penetrating into the welded portion during welding diffuses into the weld metal and the material to be welded, and is accumulated in the stress concentration portion, thereby causing low-temperature cracking. H is supplied from various sources, but when welding is performed in a state where the cleanliness of the welded portion and the gas-shielded conditions are tightly controlled, moisture (H 2 O) becomes a main source of H, and the amount of this moisture strongly affects the amount of diffusible hydrogen in the welded joint.
When the steel sheath has a slit, moisture in the atmosphere easily intrudes into the flux through the slit. Therefore, it is preferable to prevent moisture in the atmosphere from entering the flux through the steel sheath during a period from the production of the welding wire to the use of the welding wire by removing the slit of the steel sheath. When the steel sheath has a slit and the period from the production of the wire to the use of the wire is long, it is preferable to vacuum-pack the entire flux-cored wire or store the flux-cored wire in a container that can be kept in a dry state in order to prevent the intrusion of the supply source of moisture H.
(welding wire diameter)
The diameter of the flux-cored wire of the present disclosure is not particularly limited, but is, for example, from φ 1.0 to φ 2.0mm. The diameter of a general flux-cored wire is phi 1.2-phi 1.6mm.
(filling Rate)
The filling ratio of the flux-cored wire of the present disclosure is not particularly limited as long as the above-described conditions are satisfied. In view of the filling rate of a general flux-cored wire, the lower limit value of the filling rate of the flux-cored wire of the present disclosure may be set to 8%, 10%, or 12%, for example. Further, the upper limit value of the filling rate of the flux-cored wire of the present disclosure may be set to, for example, 28%, 25%, 22%, 20%, or 17%.
In addition, the quality of the steel skin and the quality of the flux were measured separately when the filling rate was calculated.
< method for producing flux-cored wire >
Next, a method of manufacturing the flux-cored wire of the present disclosure will be described.
The manufacturing method described below is an example, and the method of manufacturing the flux-cored wire of the present disclosure is not limited to the following method.
(case of flux-cored wire having seamless shape)
The method for manufacturing the flux-cored wire with the seamless shape comprises the following steps: a step of preparing a flux; forming a U-shaped open pipe by using a forming roll while conveying the steel strip in the longitudinal direction; a step of supplying flux into the open tube through the opening of the open tube; butt welding opposite edge portions (circumferential end portions) of the opening of the tube to obtain a seamless tube; drawing the seamless tube to obtain a flux-cored wire having a predetermined wire diameter; and annealing the flux-cored wire during or after the drawing process.
The flux is prepared so that the components of the flux-cored wire fall within the above-described predetermined ranges. Furthermore, it should be noted that: the flux filling rate determined by the width and thickness of the steel strip, which is the material of the steel sheath, and the filling amount of the flux also affects the respective component amounts of the flux-cored wire.
Butt welding is performed by resistance welding, laser welding, TIG welding, or the like.
In addition, the flux-cored wire is annealed during or after the completion of the wire drawing process in order to remove moisture in the flux-cored wire. In order to set the H content of the flux-cored wire to 12ppm or less, it is preferable that the annealing temperature is 650 ℃ or higher and the annealing time is 4 hours or longer. In order to prevent deterioration of the flux, the annealing temperature is preferably set to 900 ℃ or lower.
The flux-cored wire having no slit-like gap after butt seam welding has a cross section in which no weld mark is observed if the flux-cored wire is ground and etched, and no weld mark is observed if the flux-cored wire is not etched. Therefore, the above is sometimes referred to as seamless. For example, in p.111, published by the welding society under the heading of new welding and joining technology (2008), a flux-cored wire having no slit-like gap after butt seam welding is described as a seamless wire. The gap of the steel sheath of the flux-cored wire is brazed, and a flux-cored wire without slit-shaped gap can be obtained.
(case of flux-cored wire having slit-shaped gap)
The method for manufacturing a flux-cored wire having a slit-shaped gap is the same as the method for manufacturing a flux-cored wire having a seamless shape except that the method includes a step of forming an open pipe and butt-welding ends of the open pipe to obtain a pipe having a slit-shaped gap instead of a step of butt-welding circumferential ends of the open pipe to obtain a seamless pipe. The method for manufacturing a flux-cored wire having a slit-shaped gap may further include a step of caulking the end portion of the butted open pipe.
In a method for manufacturing a flux-cored wire having a slit-shaped gap, a tube having a slit-shaped gap is drawn.
< method for producing welded Joint >
Next, a method of manufacturing a welded joint (welding method) of the present disclosure will be described.
The method for manufacturing a welded joint of the present disclosure includes a step of welding steel materials using the flux-cored wire of the present disclosure described above.
In the method of manufacturing a welded joint of the present disclosure, it is preferable that the welding method be gas shielded arc welding.
In the method for manufacturing a welded joint of the present disclosure, the type of steel (material to be welded) as a base material of the welded joint is not particularly limited, but P can be suitably used, for example CM A steel material having a low-temperature cracking sensitivity of 0.24% or more, particularly a high-strength steel sheet having a tensile strength of 590MPa to 1700MPa and a sheet thickness of 20mm or more.
In the method for manufacturing a welded joint of the present disclosure, it is preferable that the method further include a step of welding the steel material using the flux-cored wire of the present disclosure in any one of 1 pass to 1 pass or more of the final passes. In the case of welding with only 1 pass, the flux-cored wire of the present disclosure is used in these 1 pass.
The polarity of the flux-cored wire may be either positive or negative, but is preferably positive, since it is so small that the effect on the diffusible hydrogen amount and the spatter generation amount of the weld metal is negligible.
In the method for manufacturing a welded joint of the present disclosure, the type of shielding gas used in the case of performing gas shielded arc welding is not particularly limited. As the shielding gas in the method for producing a welded joint of the present disclosure, it is preferable to use a generally used 100 vol% carbonic acid gas and Ar and 3 to 30 vol% CO 2 And the like. In addition, the shielding gas at the time of welding using the flux-cored wire of the present disclosure may also contain 5 vol% or less of O 2 And (3) air. Since these gases are inexpensive, welding using these gases is advantageous in industrial use.
The welding posture in the method of manufacturing a welded joint of the present disclosure is not particularly limited. In the method of manufacturing a welded joint of the present disclosure, the welding posture may be any one of a downward posture, a lateral posture, a standing posture, and an upward posture.
The welded joint obtained by the method for producing a welded joint of the present disclosure includes a steel material serving as a base material and a welded portion composed of a weld metal and a weld heat affected zone. The tensile strength of the obtained weld metal is preferably a high strength of 590 to 1200MPa, for example.
Examples
Next, the feasibility and effects of the present disclosure will be further described in detail by way of the present disclosure examples and comparative examples, but the following examples are not limited to the present disclosure, and design changes following the gist described above and described below are included in the technical scope of the present disclosure.
(production of flux-cored wire)
The flux-cored wires of the present disclosure and comparative examples were manufactured by the method described below.
First, a U-shaped open pipe is obtained by forming a steel strip with a forming roll while conveying the steel strip in the longitudinal direction. The flux is supplied into the open tube through the opening of the open tube, and the opposite edge portions of the opening of the open tube are butt welded to obtain a seamless tube.
The seamless tube was drawn to obtain a flux-cored wire having no slit-like gap. Wherein, a part of the sample was made into a tube with slit-shaped gap without seam welding, and the tube was drawn.
In this manner, a final flux-cored wire having a diameter of phi 1.2mm was produced.
In addition, during the wire drawing operation of these flux-cored wires, the flux-cored wires were annealed at a temperature ranging from 650 to 950 ℃ for 4 hours or more. After trial production, a lubricant is coated on the surface of the welding wire. The compositions of these flux-cored wires are shown in tables 1-A to 1-F.
The unit of the metal component content, the oxide content, the fluoride (specific fluoride) content, the Na-containing compound content, the K-containing compound content, and the iron powder content of the welding wires shown in tables 1-a to 1-F is mass% with respect to the total mass of the flux-cored wire. In the table, "mass% relative to the total mass of the flux-cored wire" is simply referred to as "mass%", and "metal component in the chemical composition of the wire" is simply referred to as "chemical component".
[ Table 1-A ]
[ Table 1-B ]
[ Table 1-C ]
[ Table 1-D ]
[ Table 1-E ]
[ Table 1-F ]
The remainder of the flux-cored wires shown in tables 1-a to 1-F (i.e., the components other than the components shown in the tables) were iron and impurities.
Among the flux-cored wires shown in the table, the flux-cored wire described as "seamless" in the column of "wire structure" has a seamless shape, and the flux-cored wire described as "slit-shaped gap" is a wire having a slit-shaped gap. Unless otherwise specified in the "remark" column, the welding wire is coated with palm oil as a lubricant, and the welding wire described as "PTFE oil" is a welding wire coated with PTFE oil.
The respective elements contained in the flux-cored wires shown in tables 1-A to 1-F are in the form of steel sheath or metal powder.
In tables 1-a to 1-F, values outside the range specified in the present disclosure are underlined.
In tables 1-a to 1-F, the blank in the tables related to the content of the chemical component, the compound, and the like means that the chemical component, the compound, and the like are not intentionally contained. These chemical components, compounds, etc. may also be inevitably mixed or generated.
[ evaluation ]
The flux-cored wires of the present disclosure and comparative examples were used to perform gas shielded arc welding by upward standing welding, and thus were evaluated. Specifically, the evaluation was performed by the method described below.
As a welded steel sheet, 780MPa grade steel having a sheet thickness of 50mm and a tensile strength was used, and the type of welding gas at the time of evaluation was set to Ar-20% by volume CO 2 And (3) gas. In the evaluation, the welding current was set to be dc, and the polarity of the welding wire was set to be positive.
The welding conditions at the time of evaluation were set as described in table 2.
TABLE 2
Electric current Voltage (V) Speed of speed Heat input
A V mm/min kJ/mm
220 30 16 25
(evaluation of oxygen amount of weld Metal)
The oxygen content of the weld metal obtained by gas shielded arc welding using the flux-cored wires of the present disclosure and comparative examples was evaluated.
The oxygen content of the weld metal is measured by an inert gas fusion infrared absorption method using a needle (pin) that cuts an analysis sample for oxygen content of the weld metal from a portion at the center of the plate thickness and at the center of the width of the weld metal in the longitudinal direction of the welded joint.
The oxygen content was set to 380ppm or less as A, to more than 380ppm and 450ppm or less as B, and to more than 450ppm as C.
(evaluation of Low temperature toughness)
Using the flux-cored wires of the present disclosure and comparative examples, a steel plate was gas-shielded arc welded, and 3 impact test pieces (V-notch test pieces having a notch depth of 2 mm) were collected from the center in the plate thickness direction of the weld metal.
For 3 impact test pieces, the test according to JIS Z2242 was carried out at-196℃C: charpy impact test of 2005.
Then, the case where the average value of Charpy impact absorption energy at-196℃of 3 impact test pieces was 34J or more was regarded as "pass", and the case where it was less than 34J was regarded as "fail".
(arc stability (bead Forming))
Fillet welding was performed using the flux-cored wires of the present disclosure and comparative examples, and bead formability was evaluated from the side angle. Fig. 1 is a view showing a state of a bead shape at a weld metal 8 when fillet welding is performed in a state where a steel plate (upper plate) 6 is in contact with a steel plate (lower plate) 7 in a T shape (i.e., a right angle). The definition of the side angle 5 is shown in fig. 1. In the present specification, as shown in fig. 1, an angle formed by the bead seam of the steel plate (upper plate) 6 and the weld metal 8 is set as a side angle 5a, and an angle formed by the bead seam of the steel plate (lower plate) 7 and the weld metal 8 is defined as a side angle 5b. The total of the side surface angle 5a and the side surface angle 5B is 200 degrees or more, and the case where the angle is less than 200 degrees is determined as "a", and the case where the angle is less than 200 degrees is determined as "B".
(comprehensive judgment)
The case where the oxygen amount of the weld metal is evaluated as "a" or "B" and the low temperature toughness is evaluated as "acceptable" is regarded as "acceptable", and the case where the oxygen amount of the weld metal is evaluated as "C" and the low temperature toughness is evaluated as "unacceptable" is regarded as "unacceptable".
In addition, the influence of the composition of the steel sheet (base material) in the welded metal after welding is extremely low, and therefore, the influence of the base material in the evaluation test can be said to be extremely low.
TABLE 3
It can be seen that: the flux-cored wire of the present disclosure has a small oxygen content in the weld metal, and the obtained weld metal has excellent low-temperature toughness.
On the other hand, the comparative example did not satisfy any of the requirements specified in the present disclosure, and therefore failed in 1 or more evaluation items.
The entire contents of the disclosures of japanese patent nos. 2021-162397 are incorporated herein by reference.
All documents, patent applications and technical standards described in this specification are incorporated by reference into this specification to the same extent as if each document, patent application and technical standard were specifically and individually described to be incorporated by reference.
Description of symbols
5a, 5b side angle
6 steel plate (Upper plate)
7 steel plate (lower plate)
8 weld metal

Claims (10)

1. A flux-cored wire for welding comprising a steel sheath and a flux filled in the steel sheath,
the metal components in the chemical composition of the flux-cored wire are as follows, in mass% relative to the total mass of the flux-cored wire:
C：0.020～0.800％、
Si：0.20～0.80％、
Mn：15.0～30.0％、
P：0～0.050％、
S：0～0.050％、
Cu：0～10.0％、
Ni：1.0～10.0％、
Cr：0～2.0％、
Mo：0～10.0％、
Nb：0～5.0％、
V：0～5.0％、
W：0～10.0％、
Mg：0～1.00％、
Al：0～3.0％、
Ca：0～0.100％、
Ti：0～3.000％、
B：0～0.1000％、
REM：0～0.100％、
Bi：0～0.050％、
N：0.050～1.000％、
o:0 to 0.020%, and
the remainder: fe and impurities are mixed with each other,
the oxides and fluorides in the chemical composition of the flux-cored wire, in mass% relative to the total mass of the flux-cored wire, are:
TiO of Ti oxide 2 The total of the converted values is 3.00 to 8.00 percent,
SiO of Si oxide 2 The total of the converted values is 0.10 to 1.00%,
ZrO of Zr oxide 2 The total of the converted values is 0 to 0.80%,
al of Al oxide 2 O 3 The total of the converted values is 0 to 0.80%,
containing K 2 SiF 6 、K 2 ZrF 6 、NaF、Na 3 AlF 6 、CaF 2 MgF (MgF) 2 Any one of 1 or more specific fluorides, the total of which is 0.10 to 2.00%,
contains Na oxide, naF and Na 3 AlF 6 The total of Na-containing compounds of at least 1 of the above compounds is 0.01 to 2.00%, wherein Na oxide is Na 2 The value of the conversion of O,
contains K oxide, K 2 SiF 6 K is as follows 2 ZrF 6 The total of K-containing compounds of at least 1 of the above compounds is 0.01-2.00%, wherein K oxide is K 2 And (5) converting the value into O.
2. The flux-cored wire of claim 1, wherein the total content of Mg, al, and Ca in the metal component is 0.01% or more by mass% relative to the total mass of the flux-cored wire.
3. The flux-cored wire of claim 1 or claim 2, wherein the Si content in the metal component is Si:0.25 to 0.80 percent.
4. The flux-cored wire of any one of claims 1 to 3, wherein a mass ratio of the Mn content to the Ni content in the metal component, i.e., mn/Ni, is 1.20 or more.
5. The flux-cored wire of any one of claims 1 to 4, wherein X is 0.10 to 160.00 calculated by the following formula A,
X＝(8×CaF 2 +5×MgF 2 +5×NaF+5×K 2 SiF 6 +5×K 2 ZrF 6 +Na 3 AlF 6 )/
(SiO 2 +Al 2 O 3 +ZrO 2 +0.5×MgO+CaO+0.5×Na 2 O+0.5×K 2 O+MnO 2 +FeO) type A
In formula A, caF 2 、MgF 2 、NaF、K 2 SiF 6 、K 2 ZrF 6 Na and Na 3 AlF 6 The content of the compound represented by each chemical formula in mass% relative to the total mass of the flux-cored wire, and furthermore, siO 2 SiO representing Si oxide 2 Total of converted values, al 2 O 3 Al representing Al oxide 2 O 3 Sum of converted values, zrO 2 ZrO representing Zr oxide 2 Conversion toThe sum of the values, mgO represents the sum of MgO converted values of Mg oxides, caO represents the sum of CaO converted values of Ca oxides, na 2 O represents Na of Na oxide 2 Total of O converted values, K 2 O represents K of K oxide 2 Total of O conversion values, mnO 2 MnO representing Mn oxide 2 The total of converted values, feO represents the total of FeO converted values of Fe oxide,
furthermore, the SiO in formula A 2 Converted value, the Al 2 O 3 Converted value, the ZrO 2 Conversion value, mgO conversion value, caO conversion value, na conversion value 2 O conversion value, said K 2 O conversion value, mnO 2 The converted value and the FeO converted value are expressed as mass% relative to the total mass of the flux-cored wire.
6. The flux-cored wire of any one of claims 1 to 5, which comprises an oxide of Mg and MgF 2 The total of at least 1 kind of Mg-containing compounds is 0.01-2.00%, wherein the Mg oxide is converted into MgO.
7. The flux-cored wire of any one of claims 1 to 6, wherein the steel sheath has no weld at the joint.
8. The flux-cored wire of any one of claims 1 to 6, wherein the steel sheath has a weld at a seam.
9. The flux-cored wire of any one of claims 1 to 8, coated with one or both of polytetrafluoroethylene oil and perfluoropolyether oil on a surface.
10. A method for producing a welded joint, comprising the step of welding a steel material using the flux-cored wire of any one of claims 1 to 9.
CN202280032387.1A 2021-09-30 2022-09-30 Flux-cored wire and method for manufacturing welded joint Pending CN117241914A (en)

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WO2015068273A1 (en) 2013-11-08 2015-05-14 新日鐵住金株式会社 Flux-cored wire for gas shield arc welding, and method for welding cryogenic steel using same
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