JPH10180487A - Flux cored wire for self shield arc welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flux cored wire for self shield arc welding having good welding workability in all position welding of horizontal position, vertical posi tion, capable of obtaining a sound weld zone extremely reduced in the defect of a blow hole, etc., and excellent in the toughness of a weld metal. SOLUTION: In a steel outer shell, the flux, which contains, by weight in wire total weight, 1.9-3.0% Al, 0.4-2.0%, Mg, 0.7-2.7% metal fluoride (in term of fluorine), 0.1-3.0% Li ferrite and 1.1-4.0% Ni+Mn (including steel outer shell), is filled in a flux filling rate of 10-30 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flux-cored welding wire used in self-shielded arc welding that does not require a shielding gas, and has good welding workability in all positions such as horizontal welding and vertical welding. The present invention relates to a flux-cored wire for self-shielded arc welding, which has very few pore defects such as blowholes and has good toughness of a weld metal and can obtain a healthy weld.

[0002]

2. Description of the Related Art As is well known, the self-shielded arc welding method does not require externally supplying a shielding gas for preventing the performance of a weld metal from deteriorating due to solid solution of nitrogen in the atmosphere in a molten metal. For self-shielded arc welding, in which a flux that fills the vagina surrounded by a steel shell contains components that generate gas around the arc and prevent nitrogen from entering. This is a welding method using a flux-cored wire (hereinafter referred to as a self-shielded wire) as a consumable electrode.

[0003] This self-shielded arc welding method is simple because it does not require an external shielding gas.
It has been mainly used in outdoor on-site construction where welding is performed not only in downward welding but also in all positions such as horizontal welding and vertical welding. In recent years, the simplicity of the self-shielded arc welding method has been attracting attention in the field of thin steel plates such as houses and lightweight steel frames. In such a thin plate field, the so-called wire diameter (wire diameter) of 1.2 to 2.4 mm is used. A small diameter self-shielded wire is used, especially a wire diameter of 1.4.
Those having a thickness of 1.6 mm are frequently used.

A conventional self-shielding wire is a shielding agent for forming a slag in a flux and enclosing a weld metal, and partially evaporating by arc heat to shield an arc atmosphere and a molten pool from the atmosphere. As it contains a large amount of fluoride, Li-based oxide, carbonate, etc.,
Compared to flux-cored wire for gas shielded arc welding, the amount of spatter generated is larger, and the slag solidification is slower in all positions of horizontal welding and vertical welding. Sex was bad. In addition, since a large amount of Al, Mg, etc. is contained as a shielding agent (more specifically, a denitrifying and deoxidizing agent for preventing the generation of pores of the weld metal due to nitrogen and oxygen entering during welding), the welding metal Were coarsened and the toughness of the weld metal was poor.

Conventionally, for example, JP-A-3-118993 and JP-A-4-13497 disclose welding by adjusting the component values of metal fluoride, Al, Mg, Mn, C and the like contained in the flux. There has been proposed a self-shielded wire having improved workability. For example, Japanese Patent Publication No. 58-57280, Japanese Patent Publication No. Sho 62
In JP-A-25479 and JP-A-5-393, the toughness of the weld metal is improved by incorporating a lithium oxide, a basic / neutral oxide, an iron-based oxide, etc. in the flux. Self-shielded wires have been proposed.
However, these self-shielded wires have room for improvement in that both the welding workability and the toughness of the weld metal can be satisfied.

[0006]

The present invention has good welding workability in all positions of welding, such as horizontal welding and vertical welding, and has very few pore defects such as blowholes and good toughness of a weld metal. It is an object of the present invention to provide a flux-cored wire for self-shielded arc welding in which a sound weld can be obtained and the application of self-shielded arc welding can be expanded.

[0007]

The flux-cored wire for self-shielded arc welding according to the present invention has an Al content of 1.9% by weight based on the total weight of the wire in a steel sheath.
3.0%, Mg: 0.4 to 2.0%, metal fluoride (in terms of fluorine): 0.7 to 2.7%, Li ferrite: 0.1 to 2.7%
A flux containing 1 to 3.0% and Ni + Mn: 1.1 to 4.0% (including a steel outer cover) so that the flux filling rate becomes 10 to 30% by weight. It is characterized by the following.

As described above, in the conventional self-shielded wire, the shielding agent to be contained in the flux contains Al and Mg as essential components, and is a fluoride-based or L-based material.
It was based on i-oxide. In the case of fluoride-based materials, when importance is placed on ensuring good welding workability, the amount of fluoride is relatively reduced, while the amount of Al is increased to ensure shielding properties. The toughness of the weld metal is sacrificed by a large amount of Al, and the amount of Al decreases to some extent. In the case of Li oxide type, although the toughness of the weld metal due to the wire is excellent, the amount of spatter generated is large, the weld bead tends to sag in horizontal welding or vertical welding, and the welding workability in all position welding is improved. It was bad.

In the present invention, it has been found that Li ferrite (Li iron-based oxide) is particularly effective in improving toughness, and Li ferrite for improving the toughness is replaced with Al, Mg and metal fluoride as shielding agents. It is added together with. On the other hand, Al is a strong ferrite-forming element, and its addition increases coarse pro-eutectoid ferrite to lower toughness. Therefore, an increase in coarse proeutectoid ferrite is suppressed by adding an appropriate amount of austenite forming elements such as C, Mn, and Ni. Thereby, good toughness can be ensured. From the viewpoint of not deteriorating the welding workability, the Li ferrite and Mg are added in appropriate amounts.

As described above, according to the present invention, Al, M
g, metal fluoride, Li ferrite, austenite forming element, etc. by adding appropriate amount of each flux component, it has good welding workability in all position welding and extremely few pore defects such as blow holes A self-shielded wire having good toughness and a sound weld can be provided.

The reasons for limiting the configuration of the present invention will be described below. Al is added in an appropriate range of 1.9 to 3.0% by weight based on the total weight of the wire, and is added as an essential component in order to secure the shielding property. If the Al content is less than 1.9% by weight, the shielding properties are poor, and pore defects such as pits and blow holes due to insufficient deoxidation and denitrification occur in the weld metal.
If it exceeds 3.0% by weight, the crystal grains of the weld metal become coarse,
It is not good because the toughness of the weld metal is reduced. A particularly preferred range of the Al component is 2.2 to 2.7% by weight. As for the shielding property, it is important to balance the component values of the metal fluoride and Mg. As for the addition of Al, it may be used alone, or Al-Mg, Al-Ca, Al-Li,
It may be added in the form of an alloy such as Fe-Al.

Mg is added in an appropriate range of 0.4 to 2.0% by weight based on the total weight of the wire, and is added as an essential component in order to ensure shielding properties. Mg has a strong deoxidizing function and becomes a metal vapor by the arc heat and exhibits a shielding effect of shielding an arc atmosphere from the atmosphere. If Mg is less than 0.4% by weight, the shielding property is poor and pits, Many welding defects such as blow holes occur,
If it exceeds 2.0% by weight, the amount of spatters generated is undesirably increased. A particularly preferred Mg component range is 0.6 to 1.5.
% By weight. As for the shielding property, it is important to balance the component values between Al and the metal fluoride. Mg is Al-
It is common to add in the form of Mg alloy. In addition,
As will be described later, when an appropriate amount of metallic Mg alone is added, the arc becomes stronger, which has the effect of suppressing the occurrence of spatter.

The proper range of the metal fluoride is 0.7 to 2.7% by weight in terms of fluorine based on the total weight of the wire, and is added as an essential component in order to secure the shielding property. The metal fluoride is both a shielding agent and a slag forming agent. If the metal fluoride is less than 0.7% by weight in terms of fluorine, the shielding properties are poor and pores which are welding defects such as pits and blow holes are generated. On the other hand, droplets tend to gradually increase with an increase in the amount of metal fluoride added,
If the content exceeds 2.7% by weight, the size of the droplet becomes excessively large, and the spatter of large particles increases, which is not preferable. As for the metal fluoride, the component value balance with Al and Mg is important, and a particularly preferable metal fluoride component range is 1.0 to 1.0 in terms of fluorine.
2.0% by weight. As such a metal fluoride, for example, SrF ₂ and BaF ₂ are particularly preferable in terms of less spatter, and CaF ₂ is also effective.

Li ferrite (Li iron oxide: LiF
eO ₂ ) has an appropriate range of 0.1% of the total wire weight.
To 3.0% by weight, and added as an essential component for improving the toughness of the weld metal. If the content of Li ferrite is less than 0.1% by weight, the effect of improving toughness is not sufficiently exhibited. On the other hand, if the content exceeds 3.0% by weight, the weld bead tends to sag in horizontal welding or vertical welding, and welding in all positions is performed. It is not good because workability deteriorates. A particularly preferred component range of Li ferrite is 0.5 to 2.0% by weight.

Ni + Mn is 1.1 per the total weight of the wire.
~ 4.0% by weight (however, including the steel skin)
In order to suppress an increase in coarse proeutectoid ferrite due to the addition of l, Ni or Mn which is an austenite forming element
Is added as an essential component.
If Ni + Mn is less than 1.1% by weight, the effect of suppressing coarse proeutectoid ferrite is not sufficiently exhibited, and the toughness of the weld metal is low. If it exceeds 4.0% by weight, the strength of the weld metal is significantly increased, and the welding is rather performed. This is not good because the toughness of the metal deteriorates. It is to be noted that the amount of Ni + Mn includes not only the flux but also the steel shell, and Mn is generally included in the steel shell (band steel hoop).

C is desirably added to the flux in a range of 0.19% by weight or less based on the total weight of the wire in order to secure the tensile strength of the weld metal. When a metal carbonate is added to the flux as needed as described later, C of the metal carbonate is also included. The amount of C added is 0.
If it exceeds 19% by weight, excessive carbides are formed and the toughness of the weld metal is lowered, which is not good. A particularly preferred range for C is 0.12% by weight or less. Here, the lower limit of C is 0.04% by weight from the viewpoint of securing the strength of the weld metal.
It is about. In addition, as a C source, a graphite form,
Alloys containing C such as Fe-Mn can be used.

As described above, SrF is used as the metal fluoride.
_2, BaF _2, but CaF ₂ and the like, when using the SrF ₂ powder, water content 5000ppm or less of SrF ₂
Preferably, a powder is used. That is, SrF ₂ is
Generally, it is produced from strontium carbonate by the wet method as shown in the following formula. SrCO ₃ + 2HF → SrF ₂ + H ₂ O + CO ₂

Therefore, the generated SrF ₂ powder is
Since it contains a large amount of water and has an unstable crystal structure, it easily absorbs moisture. When SrF ₂ powder having a water content exceeding 5000 ppm is used as a flux component, pores are easily generated in the weld metal, and the porosity resistance is deteriorated. Specifically, when the generated SrF ₂ powder is fired at 300 ° C. or higher, the water content becomes 5000 ppm or less, and the firing stabilizes the crystal structure. More preferably, the water content is 1000p
pm following SrF ₂ powder is good, for example, 600 ° C. × 1h
At r, a SrF ₂ powder having a water content of about 500 ppm is obtained. By sintering in this way, S having a moisture content of 5000 ppm or less
By using rF ₂ powder, the moisture absorption properties of the wire are improved, and the porosity resistance is improved.

When a single metal Mg is added as one of the above-mentioned Mg sources, the single metal Mg has the effect of strengthening the arc and suppressing the occurrence of spatter. When adding metallic Mg alone, the appropriate range for metallic Mg alone is 0.01 to 0.5% by weight based on the total weight of the wire. Metal Mg simple substance is 0.0
If it is less than 1% by weight, the effect of suppressing spatter is not sufficiently exhibited,
On the other hand, when the content exceeds 0.5% by weight, spatter increases, which is not good. In addition, even when the metal Mg alone is added, the total amount of added Mg, including the metal Mg alone, is restricted to the appropriate range of 0.4 to 2.0% by weight described above.

In the present invention, the above-described L
An oxide other than i-ferrite (Li iron-based oxide) may be added to the flux in a range of 2.0% by weight or less based on the total weight of the wire. Oxide is a slag forming agent that satisfactorily shapes the shape of the weld bead.
The amount of spatters increases and welding workability deteriorates. In order to obtain a welding bead shape shaping effect, the lower limit of this oxide is about 1.0% by weight, and as an oxide other than Li ferrite, for example, TiO ₂ , SiO _{2 and the} like are effective.
It should be noted that Ca ferrite is an oxide that has a relatively small increase in spatter even when added.

In the present invention, if necessary, the metal carbonate may be added to the flux in the range of 0.25% by weight or less based on the total weight of the wire in terms of CO ₂ . Metal carbonates such as BaCO ₃ are decomposed by arc heat and exhibit a shielding effect of shielding the arc atmosphere from the atmosphere. However, if the amount of addition exceeds 0.25% by weight in terms of CO ₂ , the amount of spatters increases and welding workability deteriorates. To obtain the shielding effect, the lower limit of the metal carbonate is about 0.1% by weight.

In the present invention, if necessary, Zr may be added to the flux in the range of 0.01 to 0.5% by weight based on the total weight of the wire. Zr forms a nitride and has the effect of improving the toughness of the weld metal. Zr is 0.01
If the amount is less than 0.5% by weight, the effect of improving toughness cannot be sufficiently obtained. If the amount exceeds 0.5% by weight, the arc becomes unstable, so that the amount of spatters increases and welding workability deteriorates. 01 to 0.5% by weight.

In the present invention, if necessary, rare earth metal (rare earth metal) may be added in an amount of 0.01 to 0.01 wt.
It may be added to the flux in the range of 0.5% by weight. C
Rare earth metals such as e, La, and Y exhibit an effect of improving the toughness of the weld metal. If the rare earth metal is less than 0.01% by weight, the effect of improving toughness cannot be sufficiently obtained.
On the other hand, if it exceeds 0.5% by weight, the amount of spatters increases and welding workability deteriorates. Therefore, the appropriate range of the rare earth metal is 0.01 to 0.5% by weight. The addition form of the rare earth metal is REM-Ca-Si [(Ce.La)
-Ca-Si] and the like.

In addition, the flux composition naturally includes iron powder. As is well known, iron powder has a good fluidity, so that flux can be stably added to the inside of the steel shell, thereby stabilizing the flux filling rate (flux rate), and increasing the welding speed during welding. It stabilizes the arc.

Although the flux composition has been described above, the flux filling rate is also important, and the appropriate range of the flux filling rate with respect to the total weight of the wire is 10 to 30% by weight.
It is. If the flux filling ratio is less than 10% by weight, the individual contents of the required flux components described above are insufficient, and a satisfactory effect by each flux component cannot be obtained.
In addition, if it exceeds 30% by weight, the amount of slag becomes excessive,
This is not preferable because wire drawability during manufacturing is deteriorated.

The present invention is directed to a so-called small-diameter self-shielded wire having a wire diameter of 1.2 to 2.4 mm as described above. The self-shielded wire according to the present invention has a wire sectional shape shown in FIG. (A) to FIG.
As shown in (c), a structure in which a steel outer skin (usually made of carbon steel) is folded inward is preferable. In the case of a structure with a steel shell folded inside, the spray transfer of droplets (droplet transfer due to fine-grained state) is promoted, and the effect of the shielding agent in the flux is enhanced, so that the porosity resistance is improved. Is effective. From the viewpoint of wire productivity, an Apple type structure shown in FIG.

The self-shielding wire according to the present invention
A tetrafluoroethylene-based wire feed lubricant or molybdenum disulfide (Mo) is used as a wire feed lubricant on the wire surface.
S ₂ ) It is preferable to apply a system wire feeding lubricant. Wire projection length (distance between welding tip and base metal) during welding is 3
When the length is as long as about 0 mm, the amount of spatter generated tends to increase. As one means for reducing the occurrence of this spatter,
Improving the feedability of the wire fed by the wire feeding device and the welding torch attached to the wire feeding device is mentioned. Therefore, it is preferable that the wire surface is coated with a tetrafluoroethylene-based or molybdenum disulfide-based wire feeding lubricant.

In the case of a wire using an ethylene tetrafluoride-based wire feeding lubricant, an ethylene tetrafluoride-based wire feeding lubricant is applied to the surface of the wire so as to have a fluorine content of 1 to 1000 ppm based on the total weight of the wire. What was done is good. If the application amount is less than 1 ppm, there is no effect of improving wire feedability, and if it exceeds 1000 ppm, the feed lubricant is excessively deposited on the conduit liner that guides the wire in the welding torch, and wire clogging is likely to occur. Absent. In addition, a more preferable range is 10 to 200 pp.
m.

In addition, molybdenum disulfide wire feeding lubrication
In the wire using the agent, the wire 10 k
0.001 to 3 g of MoS per g_TwoM to be a quantity
oS _TwoIt is preferable to apply a system wire feeding lubricant. Application
If the amount is less than 0.001 g, there is no effect of improving the wire feeding property.
In addition, if it exceeds 3 g, the conduit liner
Wire clogging easily due to excessive accumulation of feed lubricant
It is not good because it becomes. Incidentally, a more preferable range is 0.1.
１．５1.5 g.

[0030]

Embodiments of the present invention will be described below.

[0031]

EXAMPLES Self-shielded wires having the specifications shown in Tables 1 and 2 were produced by a conventional method. The wire diameter is 1.6mm,
The wire had a wrap type structure as shown in FIG. 1 (c). However, in Table 2, No. Twenty-three wires of the present invention are:
The cross-sectional shape was an apple type structure shown in FIG. The steel skin is made of ordinary carbon steel (JIS G3141)
SPCC), and the steel outer shell component (% by weight) is C: 0.04%, Si: 0.01%, Mn: 0.35.
%, P: 0.015%, and S: 0.007%.

Using these self-shielded wires, V
Test plate (JISG 3106 SM4)
90B, board thickness 20mm x width 150mm x length 500m
m, a groove angle of 45 °, and a groove gap of 12 mm) were subjected to multilayer welding in a downward position, and welding workability and welded portion performance (porosity resistance, toughness according to JIS Z 3313) were investigated. The welding conditions were DC positive polarity, 200 A-19 V, and a wire protrusion length of 20 mm. In addition, in order to check the weldability in all positions of welding workability, fillet welding in an upright position is performed to determine whether the weld bead is easily formed flat without drooping, that is, the ease of welding. Was examined.

The flux filling ratio was 20% by weight, including that of the comparative example. In Tables 1 and 2, M
g is added in the form of an alloy of Al-50% Mg. Therefore, the amount of Al in Tables 1 and 2 is based on Al alone and the Al-
It is the total value with the value based on 50% Mg powder. Table 2
No. 21 (1.2% by weight)
g is a value including simple substance (0.2% by weight). In addition, in the remarks column of Table 2, No. 18 wires are 6
After firing at 00 ° C for 1 hour, water content is about 500ppm
No. 5 using the SrF ₂ powder of No. The wire 23 has the Apple-shaped structure described above in cross section. In addition, No. The wire No. 24 was prepared by applying an ethylene tetrafluoride-based wire feeding lubricant so that the amount of fluorine was about 100 ppm with respect to the total weight of the wire on the wire surface. The wire No. 25 was prepared such that the amount of MoS _{2 was} 1.0 g per 10 kg of wire on the wire surface.
The oS ₂ based wire feeding lubricant is obtained by coating.

[0034]

[Table 1]

[0035]

[Table 2]

From Tables 1 and 2, No. The comparative examples 4 to 13 had the following problems. No. No. 4 has a large amount of metal fluoride, so that spatter increases and welding workability is poor.
No. Conversely, No. 5 lacked metal fluoride, so the shielding properties were poor, and pits and blowholes frequently occurred. As a result, the toughness of the weld metal was low and a sound weld was not obtained. N
o. 6 has poor shielding due to lack of Al and has pits.
Blowholes occur frequently, while No. 7 is C, Mn, Ni
Austenite forming element is added,
Since l was excessive, the crystal grains of the weld metal were coarsened and the toughness was low, and a sound weld was not obtained in both cases.

No. No. 8 lacks Mg and has poor shielding properties, causing pits and blowholes frequently. As a result, the toughness of the weld metal is low and a sound weld cannot be obtained.
o. On the contrary, No. 9 had an excessive amount of Mg, so that spatter was increased and welding workability was poor. No. No. 10 has insufficient toughness due to insufficient Li ferrite, and a healthy weld cannot be obtained.
On the other hand, in No. 11, a flat welding bead was not formed in vertical welding due to excessive Li ferrite, and welding workability was poor.

No. In No. 12, the toughness was poor because the strength of the weld metal was too high due to excessive Ni + Mn. On the other hand, No. 13 was insufficient in Ni + Mn, so that the effect of suppressing coarse pro-eutectoid ferrite by Al was not exhibited, and the toughness of the weld metal was poor.

No. 14 to 16 are examples of the present invention, but are out of the more preferable range. No.
In No. 14, C in the weld metal was slightly increased, and excessive carbide was generated, and the toughness of the weld metal was slightly poor. No. 15 is Li
Since TiO ₂ which is an oxide other than ferrite is slightly excessive, In No. 16, since BaCO ₃ which is a metal carbonate was slightly excessive, spatter was slightly generated in both of them, and welding workability was slightly poor.

On the other hand, no. Nos. 1-3 and No. 17
In the self-shielded wires of the invention examples of the present invention, the welding workability in the downward and standing postures is good,
It was found that there was no pore defect such as blowhole and the toughness of the weld metal was good and a sound weld was obtained.

No. No. 1 is an example of the present invention having a typical flux composition, and good results are obtained in both welding workability and welded portion performance. No. 3 is CaF as metal fluoride
By using the SrF ₂ and BaF ₂ without using _2, it was particularly spatter is small.

No. No. 17 shows that an appropriate amount of BaCO _{3 as} a metal carbonate was added. Sample No. 18 used SrF ₂ powder having a water content of about 500 ppm, and in particular, had little pits and blowholes and had excellent porosity. Note that the flux containing SrF ₂ , For other wires than 18, the water content of the SrF ₂ powder is about 7000 ppm. No. In No. 19, an appropriate amount of Ca ferrite and TiO _{2 as} oxides was added, and the bead appearance was particularly good.

No. No. 20 indicates that an appropriate amount of Zr was added. 22 is a rare earth metal, in this example C
By adding an appropriate amount of Ce and La in the addition form of e.La-Ca-Si, the toughness of the weld metal was particularly excellent. No. In No. 21, the amount of spatter generated was particularly small because a proper amount of Mg metal was added.

No. Reference numeral 23 denotes an apple-shaped structure (FIG. 1 (a)) having a wire cross-sectional shape. Since the effect of the shielding agent is further enhanced as compared with the wrap-type structure shown in FIG. I was No. In No. 24, an appropriate amount of ethylene tetrafluoride-based wire feed lubricant was applied to the wire surface. In No. 25, an appropriate amount of a molybdenum disulfide-based wire feeding lubricant was applied to the surface of the wire, and both wires had particularly good wire feeding properties, whereby the amount of spatter generated was particularly small.

[0045]

As described above, according to the present invention,
Flux for self-shielded arc welding, which has good welding workability in all position welding such as horizontal welding and vertical welding, has very few pore defects such as blow holes, has good toughness of weld metal, and obtains a healthy weld. It is possible to provide a cored wire, whereby the application of the self-shielded arc welding can be expanded.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an example of a cross-sectional shape of a self-shielded wire according to the present invention.

Claims (10)

[Claims] 1. A self-filling method comprising: filling a steel sheath with a flux containing the following components in a percentage by weight based on the total weight of a wire so that a flux filling rate is 10 to 30% by weight. Flux-cored wire for shield arc welding. Al: 1.9 to 3.0% by weight Mg: 0.4 to 2.0% by weight Metal fluoride (in terms of fluorine): 0.7 to 2.7% by weight Li ferrite: 0.1 to 3.0% by weight % Ni + Mn: 1.1 to 4.0% by weight (however, including a steel sheath) 2. The flux-cored wire for self-shielded arc welding according to claim 1, wherein C is contained as a flux component in an amount of 0.19% by weight or less based on the total weight of the wire. 3. The flux-cored wire for self-shielded arc welding according to claim 1, wherein SrF ₂ powder having a water content of 5000 ppm or less is used as one of the metal fluoride sources. 4. The self-shielded arc welding according to claim 1, wherein one kind of the Mg source contains 0.01 to 0.5% by weight of metallic Mg alone with respect to the total weight of the wire. Flux cored wire. 5. The flux-cored wire for self-shielded arc welding according to claim 1, wherein an oxide other than Li ferrite is contained as a flux component in an amount of 2.0% by weight or less based on the total weight of the wire. . 6. The self-shielded arc welding flux-containing flux according to claim 1, wherein a metal carbonate is contained as a flux component in an amount of not more than 0.25% by weight in terms of CO ₂ with respect to the total weight of the wire. Wire. 7. The method according to claim 1, wherein Zr is contained as a flux component in an amount of 0.01 to 0.5% by weight based on the total weight of the wire.
7. The flux-cored wire for self-shielded arc welding according to any one of 6. 8. The flux-cored wire for self-shielded arc welding according to claim 1, wherein a rare earth metal is contained as a flux component in an amount of 0.01 to 0.5% by weight based on the total weight of the wire. 9. The flux-cored wire for self-shielded arc welding according to claim 1, wherein the wire has a cross-sectional shape in which a steel sheath is folded inward. 10. As a wire feeding lubricant, an ethylene tetrafluoride-based wire feeding lubricant is applied to the surface of the wire so as to have a fluorine content of 1 to 1000 ppm based on the total weight of the wire, or 10 kg of the wire. 0.001-3g
10. The flux-cored wire for self-shielded arc welding according to claim 9, wherein a molybdenum disulfide-based wire feeding lubricant is applied so that the amount of MoS ₂ becomes.