JP2003275894A - Steel wire for gas-shielded arc welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel wire for gas-shielded arc welding using a welding robot with which stable tip wear resistance can be obtained even in the case of the condition where a feeding tip is used for a long period of time. <P>SOLUTION: In the steel wire for gas-shielded arc welding, the surface of a steel element wire containing, by mass, ≤0.12% C, 0.25 to 1.5% Si, 0.45 to 2.0% Mn and ≤0.0020% Ca is provided with a solid lubricant layer containing 10 to 70% MoS<SB>2</SB>, a 2 to 25% K compound and ≤70% copper powder in 0.2 to 1.0 g per 10 kg of the steel element wire. The surface of the solid lubricant layer is provided with a lubricant layer consisting of fatty ester and/or lubricating oil in 0.2 to 1.8 g per 10 kg of the steel element wire. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel wire for gas shielded arc welding, and particularly to a thin wire using a robot in which wear resistance (hereinafter referred to as chip wear resistance) of a power feed tip and arc stability are important. The present invention relates to a steel wire for gas shield arc welding (hereinafter referred to as a welding wire) suitable for automatic gas shield arc welding of a steel sheet.

[0002]

2. Description of the Related Art In MAG welding, an oxidizing gas such as carbon dioxide gas, a mixed gas of carbon dioxide gas and argon gas, or a mixed gas containing oxygen gas is used as a shield gas, and a consumable electrode having a diameter of 0.6 to 1.6 mm is used. This is a welding method in which welding is performed at a welding speed of 4 to 20 m / min using a welding wire, and it is necessary to stably feed the welding wire in order to maintain its stable weldability. Therefore, the surface of the welding wire has been conventionally Cu-plated or lubrication oil has been applied to improve the feedability of the welding wire and the chip wear resistance.

However, in recent years, in order to suppress the cost increase associated with the replacement of the power feeding tip in welding using a welding robot, it has been practiced to use the power feeding tip for a long time, and the power feeding tip is worn. Welding has come to be performed even in the limit state. As a result, stable re-arc startability cannot be maintained during robot welding, or the arc during welding becomes unstable, which causes a hindrance to welding work.
Therefore, various techniques for improving the feeding property of the welding wire have been proposed.

[0004] For example, Japanese Patent Laid-Open No. 5-23731 discloses a method of feeding a welding wire by holding a lubricant consisting of polytetrafluoroethylene, MoS ₂ , graphite and minerals on the surface of a raw material steel wire. A technique for improving the above is disclosed.
Further, in Japanese Patent Application Laid-Open No. 11-217578, a lubricant such as MoS ₂ or WS ₂ , ester or petroleum wax is held on the surface of a steel wire as a raw material, and the welding wire feeding property is improved. A technique for improving the above is disclosed.

[0005]

SUMMARY OF THE INVENTION
The techniques disclosed in Japanese Patent No. 23731 and Japanese Patent Laid-Open No. 11-217578 focus on improving the feedability of the welding wire, and do not consider the chip wear resistance. Therefore, when these techniques are applied to robot welding etc. where the power feed tip is used for a long time, stable re-arc startability cannot be maintained, or the arc during welding becomes unstable, which interferes with welding work. Is still unavoidable.

Therefore, an object of the present invention is to provide a gas shield arc welding steel wire (in particular, for gas shield arc welding using a welding robot) which can provide stable tip wear resistance even when the power feed tip is used for a long time ( That is, to provide a welding wire).

[0007]

[Means for Solving the Problems] The inventors of the present invention diligently studied the phenomenon in which re-arc startability and arc stability are deteriorated due to wear of the feed tip during automatic welding by a welding robot that uses the feed tip for a long time. did. As a result, it was found that the composition of the steel wire, which is the material, the composition and amount of the lubricant applied to the steel wire, and the hardness of the steel wire have a great influence.

First, regarding the components of the steel wire, by containing a predetermined amount of C, S and Mn and Ca, the short circuit at the time of welding, the feed resistance of the welding wire and the wear of the power feed tip are reduced. Is achieved. As a result, even if the power feed tip is used for a long time, good re-arc startability and stable arc state can be obtained. Next, at the tip of the power feed tip where the power feed tip and welding wire come into contact with each other, the temperature exceeds 500 ° C momentarily for each welding, so the conventionally known lubricants and ester lubricants are exposed to high temperatures. It is disassembled and decomposed, sufficient lubricity is not maintained, and the tip of the power feeding tip is slightly worn. Therefore, in the case where welding is continuously repeated like robot welding, the amount of wear at the tip of the power feed tip increases due to accumulated wear, and re-arc startability and arc stability cannot be maintained.

However, even if the temperature of the tip of the power feed tip rises, the wear of the tip of the power feed tip is suppressed by applying a solid lubricant containing a stable inorganic material, that is, a MoS ₂ , K compound even at high temperature. It As a result, good re-arc startability and stable arc state can be obtained even when the power feed tip is used for a long time.

Further, regarding the hardness of the steel wire, by limiting the product of the cross-sectional area and the hardness of the steel wire, wear at the tip of the power supply tip where the power supply tip and the welding wire come into contact is suppressed. . As a result, chip wear resistance is improved, and good re-arc startability and stable arc state can be obtained. The present invention has been made based on the above findings.

That is, the present invention provides a welding steel wire used for gas shielded arc welding, wherein C: 0.12% by mass.
Below, Si: 0.25 to 1.5 mass%, Mn: 0.45 to 2.0 mass%,
On the surface of the steel wire containing Ca: 0.0020 mass% or less, MoS
₂ : 10 to 70% by mass, K compound: 2 to 25% by mass, copper powder: 70
A solid lubricant layer containing not more than 10% by mass is contained in an amount of 0.2 to 1.0 g per 10 kg of the steel wire, and a lubricant layer made of a fatty acid ester and / or a lubricating oil is provided on the surface of the solid lubricant layer. The steel wire for gas shielded arc welding is characterized by having 0.2 to 1.8 g per unit.

In the above invention, as a first preferred embodiment, the Vickers hardness Hv and the cross-sectional area S of the steel wire are
(Mm ² ) and the coefficient A calculated from the following equation (1)
Is preferably in the range of 150 to 400. A = Hv × S (1) Hv: Vickers hardness of steel wire S: Cross-sectional area of steel wire (mm ² ) As a second preferred embodiment, the average thickness of the surface of the steel wire is It is preferable to form a Cu plating layer having a thickness of 0.5 μm or more.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION First, the reasons for limiting the components of the steel wire which is the material of the welding wire of the present invention will be explained. C: 0.12% by mass or less C is an important element for ensuring the strength of the weld metal, and has the action of lowering the viscosity of the molten metal and improving the fluidity. However, if the C content exceeds 0.12% by mass,
During welding, the behavior of the droplet and molten pool becomes unstable, a large amount of spatter occurs, and an unstable short circuit phenomenon occurs. Moreover, since the hardness of the steel wire is excessively increased, a galling phenomenon due to the welding wire occurs at the tip of the power feed tip. Therefore, C is limited to 0.12 mass% or less. In addition, in order to secure the strength of the weld metal, the lower limit of the C content is preferably 0.01% by mass.

Si: 0.25 to 1.5 mass% Si has a deoxidizing action and is an essential element for deoxidizing the weld metal. If the Si content is less than 0.25% by mass, the droplets and the molten pool oscillate during welding, not only a large amount of spatter occurs, but also deoxidation of the molten metal is insufficient,
Blow holes occur in the weld metal. Moreover, an unstable short circuit phenomenon occurs, which hinders the feedability of the welding wire. On the other hand, if the content exceeds 1.5% by mass, the toughness of the weld metal is reduced and the hardness of the steel wire is excessively increased.
Therefore, Si is limited to the range of 0.25 to 1.5 mass%.

Mn: 0.45 to 2.0 mass% Mn has a deoxidizing action like Si, and is an essential element for deoxidizing the weld metal. If the Mn content is less than 0.45 mass%, not only do droplets and molten pool oscillate during welding, a large amount of spatter occurs, but deoxidation of the molten metal is insufficient and blowholes are formed in the weld metal. Occur. Moreover, an unstable short circuit phenomenon occurs, which hinders the feedability of the welding wire. On the other hand, if the content exceeds 2.0% by mass, the toughness of the weld metal is reduced and the hardness of the steel wire is excessively increased. Therefore, Mn is limited to the range of 0.45 to 2.0 mass%.

Ca: 0.0020% by mass or less Ca is mixed in the steel wire as an impurity in steelmaking, casting or wire drawing. When the Ca content exceeds 0.0020% by mass, the arc becomes unstable due to the concentration of the arc on a part of the droplet during welding, and a large amount of spatter occurs. Moreover, an unstable short circuit phenomenon occurs, which hinders the feedability of the welding wire. Therefore, Ca is limited to 0.0020 mass% or less.

Further, in the present invention, the components of the steel wire are, in addition to the above-mentioned composition, P: 0.003 to 0.050 mass%, S:
0.050 mass% or less, K: 0.0001 to 0.0150 mass% and T
It is preferable to contain i: 0.30 mass% or less. The reason will be described. P: 0.003 to 0.050 mass% P is an element mixed in the steel wire as an impurity in the steel making and casting steps, but it has the effect of smoothing the bead shape. However, if the P content is less than 0.003% by mass,
The effect of smoothing the bead shape cannot be obtained. On the other hand, 0.0
If it exceeds 50% by mass, the viscosity of the molten metal is lowered during welding, the arc becomes unstable, and spatter of small particles increases. Therefore, it is preferable that P satisfies the range of 0.003 to 0.050 mass%.

S: 0.050% by mass or less S has the effect of lowering the viscosity of the molten metal, assisting the detachment of droplets suspended at the tip of the welding wire, and stabilizing the arc. However, when the S content exceeds 0.050 mass%, the spatter of small particles increases and the toughness of the weld metal decreases. Therefore, S is preferably 0.050 mass% or less. Note that S also has the effect of lowering the viscosity of the molten metal and smoothing the bead shape. In order to make the bead shape smooth, it is preferable to add 0.015 mass% or more of S.

K: 0.0001 to 0.0150 mass% K widens the arc (that is, softens the arc),
In addition to facilitating the transfer of droplets in arc welding,
It has the effect of making the droplets finer and further suppressing fluctuations in the feed resistance of the welding wire. This effect has a K content of 0.0001.
It is recognized in mass% or more. On the other hand, if it exceeds 0.0150% by mass, the arc length increases during welding, the droplets suspended on the tip of the welding wire become unstable, and a large amount of spatter occurs. Therefore, K is preferably in the range of 0.0001 to 0.0150 mass%. More preferably 0.0003 to 0.0030
It is% by mass. The boiling point of K is as low as about 760 ° C, and the yield in the melting stage of molten steel is extremely low. Therefore, at the stage of manufacturing the steel wire, it is preferable that K is stably contained in the steel wire by applying a potassium salt solution to the surface of the steel wire and annealing it.

Ti: 0.30% by mass or less Ti is an element that acts as a deoxidizer and further increases the strength of the weld metal. However, if the Ti content exceeds 0.30% by mass, the droplets become coarse during welding, large spatters are generated, and the toughness of the weld metal is significantly reduced. Therefore, Ti is preferably 0.30 mass% or less. In addition, in order to increase the strength of the weld metal,
It is preferable to add 0.030 mass% or more of Ti.

Further, in the present invention, in addition to the above composition, the components of the steel wire are Cr: 3.0 mass% or less, Ni: 3.0 mass%.
Hereinafter, it is preferable to contain one or more of Mo: 1.5 mass% or less, Cu: 3.0 mass% or less, and B: 0.005 mass% or less. Ie Cr, Ni, Mo, Cu and B
Are elements that both increase the strength of the weld metal and improve the weather resistance, and can be added as necessary. However, it is not necessary to set a lower limit in particular because each element exerts these effects with a small amount of addition. However, if added excessively, the toughness of the weld metal is lowered and the welding wire is significantly hardened. Therefore, when these elements are added, Cr: 3.0 mass% or less, Ni: 3.0 mass% or less, Mo:
1.5 mass% or less, Cu: 3.0 mass% or less and B: 0.005
It is preferable that the content is not more than mass%.

Further, in the present invention, it is preferable that the components of the steel strand include one or more of Zr, Nb and V in addition to the above composition. That is, Zr, Nb, and V are all elements that increase the strength and toughness of the weld metal and improve the stability of the arc, and may be added if necessary. However, it is not necessary to set a lower limit in particular because each element exerts these effects with a small amount of addition. However, if added excessively, the toughness of the weld metal is lowered and the welding wire is significantly hardened. Therefore, when one of these elements is added, the addition amount is preferably 0.55 mass% or less. When adding more than one species, the total amount of addition is preferably 0.55 mass% or less.

Furthermore, in the present invention, the components of the steel wire are
In addition to the above composition, it is preferable to add Al: 0.50 mass% or less. That is, Al is an element that acts as a deoxidizer for the weld metal and improves the stability of the arc when performing horizontal welding, and can be added if necessary. However, when added in excess of 0.50 mass%, the toughness of the weld metal is reduced. Therefore, when Al is added, it is preferably 0.50 mass% or less.

The balance of the steel wire other than the above components is
Fe and inevitable impurities. Typical unavoidable impurities are O and N, and it is preferable to limit O to 0.020 mass% or less and N: 0.010 mass% or less.
In particular, O is effective in reducing the size of the droplet during welding, so 0.0020 to 0.0080 mass% is more preferable.

Next, a method for manufacturing the welding wire of the present invention will be described. Molten steel having the above composition is melted by a known melting method using a converter or an electric furnace. Next, the obtained molten steel is manufactured into a steel material (for example, billet) by a continuous casting method, an ingot making method, or the like. After that, these steel materials are heated, hot-rolled, and then cold-rolled by a dry method (that is, wire drawing) to produce a steel wire. The conditions of hot rolling and cold rolling are not particularly limited as long as they are the conditions for forming a steel wire having a desired size and shape.

Further, this steel wire is sequentially subjected to the steps of annealing-pickling-Cu plating-drawing-lubricant application to obtain a product having a predetermined wire diameter (ie, welding wire). In the above-mentioned welding wire manufacturing process, it is preferable to anneal after applying a potassium salt solution to the surface of the steel wire before annealing. As the potassium salt solution, it is preferable to use an aqueous solution of 3 potassium citrate, an aqueous solution of potassium carbonate, an aqueous solution of potassium hydroxide or the like. The potassium salt concentration of the applied solution is preferably 0.5 to 3.0% by volume in terms of K value.

By annealing the steel wire coated with the potassium salt solution on its surface, K is stably retained in the internal oxide layer formed during the annealing. On the other hand, in the method of simply applying it on the surface or holding it during Cu plating, problems such as discoloration of Cu plating are likely to occur, and moreover, it is thermally unstable. Becomes smaller.

The annealing is carried out for the purpose of softening the steel wire and imparting K, and is preferably carried out in a temperature range of 650 to 950 ° C. in a nitrogen gas atmosphere containing water vapor. That is, when the annealing temperature is less than 650 ° C, the progress of the internal oxidation reaction is slow. On the other hand, when the temperature exceeds 950 ° C, the progress of the oxidation reaction is too fast, and it becomes difficult to adjust the internal oxidation amount. It is desirable that the annealing atmosphere has a dew point of 0 ° C. or less and an oxygen concentration of 200 volume ppm or less from the viewpoint of forming an internal oxide layer. In such an atmosphere, by annealing the steel wire whose surface is coated with the potassium salt-containing solution, oxidation progresses from the surface and the surface layer portion is internally oxidized. Potassium is reliably retained in this internal oxidation part.

The temperature and time for annealing are as follows: K content in the steel wire is 0.0003 to 0.0030 mass% and O content is
It is preferable to determine the diameter of the steel wire and the coating conditions such as the potassium salt concentration and the coating amount of the potassium salt-containing solution so as to be 0.0020 to 0.0080 mass%. Further, it is preferable that the steel wire that has been annealed is subjected to pickling, and then the surface thereof is subjected to Cu plating. The thickness of this Cu plating layer is average
It is preferably 0.5 μm or more. That is, by setting the thickness of the Cu plating layer to an average of 0.5 μm or more, defective power feeding between the power feeding tip and the welding wire is prevented, and wear of the tip portion of the power feeding tip is suppressed. In addition, preferably the average
It is 0.8 μm or more.

A solid lubricant containing MoS ₂ : 10 to 70% by mass and K compound: 2 to 25% by mass is applied to the surface of the steel wire plated with Cu as described above to obtain a solid lubricant. Form the layers. Copper powder generated in the wire drawing step described later is mixed in this solid lubricant layer. Therefore, copper powder is also included in the solid lubricant layer of the manufactured welding wire. At the tip of the power feed tip, where the power feed tip and welding wire come into contact with each other, the temperature temporarily exceeds 500 ° C each time welding is performed, so conventionally known lubricants and ester lubricants are exposed to high temperatures and decompose. Will not be able to maintain sufficient lubricity,
The tip of the power feed tip is slightly worn. Therefore, in the case where welding is continuously repeated like robot welding, the amount of wear at the tip of the power feed tip increases due to accumulated wear, and re-arc startability and arc stability cannot be maintained. Therefore, as a result of studying various lubricants, the present inventors have found that MoS ₂ and a K compound are effective for maintaining lubricity even at high temperatures and having excellent electric conductivity in the power feeding chip. However, MoS ₂ is 10 to 70% by mass, K compound is 2 to
It is necessary to satisfy the range of 25% by mass. If it deviates from this range, it becomes difficult to maintain the lubricity in a high temperature range, and it becomes difficult to maintain good chip abrasion resistance.

The MoS ₂ content is preferably 15 to 50% by mass. Further, it is more preferable that the content of the graphite is 5 to 20% by mass because the lubricity at high temperature is improved. When potassium stearate is used as the K compound,
It is preferable because the lubricity at high temperature is improved. On the other hand, copper powder generated in the wire drawing step after Cu plating is inevitably mixed in the solid lubricant layer. If the content of copper powder exceeds 70% by mass, seizure will occur in the power feed tip during welding, and the feeding of the welding wire will stop instantaneously. As a result, the arc becomes unstable, and the tip of the power feed tip wears hard. Therefore, the content of copper powder in the solid lubricant layer is 70
It is necessary to make it less than mass%.

Further, the amount of solid lubricant layer adhered is 10 kg of steel wire.
If the amount is less than 0.2 g, the effect of reducing wear on the tip of the power feeding tip cannot be obtained. On the other hand, 1.0 g per 10 kg of steel wire
Beyond the above, solid lubricant adheres to and accumulates on the inner surface of the power feed tip, hinders the feeding of the welding wire, and increases the electrical resistance between the power feed tip and the welding wire, increasing the wear of the tip of the power feed tip. . Therefore, the amount of the solid lubricant layer deposited must be within the range of 0.2 to 1.0 g per 10 kg of steel wire.

Further, in order to reduce the feeding resistance of the welding wire during welding and stabilize the feeding, a fatty acid ester or a lubricating oil is applied to the surface of this solid lubricant layer. Alternatively, a mixture of fatty acid ester and lubricating oil may be applied. In this way fatty acid esters and /
Alternatively, a lubricant layer made of lubricating oil is formed. If this lubricant layer is less than 0.2 g per 10 kg of steel wire, the effect of reducing the resistance when feeding the welding wire cannot be obtained. On the other hand, if the amount exceeds 1.8 g per 10 kg of steel wire, the welding wire slips at the feeding roller during welding, the feeding speed fluctuates significantly, and the chip wear resistance deteriorates. Therefore, the lubricant layer must satisfy the range of 0.2 to 1.8 g per 10 kg of steel wire.

Further, by applying the fatty acid ester and / or the lubricating oil to form the lubricant layer in this manner, the effect of preventing discoloration and deterioration of the surface of the steel wire due to MoS ₂ or K compound can be obtained. . Furthermore, in the welding wire of the present invention obtained through the above manufacturing process, the Vickers hardness Hv and the cross-sectional area S (mm ² ) of the steel wire are used,
It is preferable that the coefficient A calculated from the equation (1) below satisfies the range of 150 to 400. However, here, the cross-sectional area S
Indicates the area of a cross section perpendicular to the central axis of the steel wire.

A = Hv × S (1) Hv: Vickers hardness of the steel wire S: Cross-sectional area of the steel wire (mm ² ) When the hardness of the steel wire increases, when welding is performed At the feeding point where the tip of the feeding tip contacts the welding wire, wear of the tip of the feeding tip is promoted. The wear of the tip of the power feed tip is also promoted by an increase in the cross-sectional area of the welding wire, and the coefficient A calculated by equation (1) is 400
It becomes remarkable when it exceeds. However, if the coefficient A is less than 150, the contact state between the tip of the power feed tip and the welding wire becomes unstable, and the power supply state becomes unstable. As a result, the tip of the power feed tip will be severely worn and the arc will be unstable. Therefore, the coefficient A calculated from equation (1) is 1
It is preferable to satisfy the range of 50 to 400.

The hardness of the welding wire can be adjusted by the composition of the steel wire, annealing conditions and wire drawing conditions.

[0037]

[Example] A steel material (that is, a billet) produced by continuous casting was hot-rolled into a wire having a diameter of 5.5 to 7.0 mm. Then cold rolled (ie wire drawing) to a diameter of 2.0
A steel wire of 2.8 mm was prepared, and 30 to 50 g of an aqueous solution of tripotassium citrate having a concentration of 2 to 30% by volume was applied per 1 kg of the steel wire.

Then, the steel wire was N
₂ atmospheres (O ₂ concentration: 200 volume ppm or less, CO ₂ concentration:
Annealed at 0.1% by volume or less). Annealing temperature is 760 to 950 ℃
As a result, by adjusting the annealing temperature and the annealing time according to the diameter of the steel wire and the potassium salt concentration, the progress of internal oxidation of the steel wire is adjusted, and the K content and the O content of the steel wire are adjusted. It was adjusted.

After being annealed in this manner, the steel wire was pickled and further Cu-plated. Next, cold wire drawing (ie, wet drawing) is applied to obtain a diameter of 1.0 mm and
A 1.2 mm welding wire was produced. With respect to some of the welding wires, a solid lubricant containing MoS ₂ and a K compound was applied by wire drawing and wire drawing, so that a solid lubricant capable of maintaining lubricity at high temperature was attached. The amount of solid lubricant adhered was adjusted by selecting the die schedule and die shape.

Table 1 shows the components of the steel wire of the obtained welding wire, the average thickness of the Cu plating layer, and the calculated value of the coefficient A.

[0041]

[Table 1]

Using these welding wires, a diameter of 800 mm
While rotating the steel pipe (25 mm thick) of the
Welding for 1 minute-10 seconds rest-3 minutes welding-10 seconds rest were repeated for a total of 600 minutes of welding. After continuous repeated welding, measure the inner diameter of the tip of the feeding tip as an index to evaluate the amount of wear at the tip of the feeding tip, and expand from the initial inner diameter based on the average value obtained from the maximum and minimum values. The rate (%) was calculated.

Here, the target value of the inner diameter enlargement ratio of the tip of the power feeding tip is set to 10% or less, and the enlargement ratio is 7% or less (good), 7% to 10% or less (Δ), 10%. The excess was evaluated as unacceptable (x). The evaluation of the chip wear resistance of the welding wire is as shown in Tables 2-3. The amounts of lubricant applied and the amounts of solid lubricant applied to each welding wire used are shown in Tables 2 and 3. The welding conditions when performing these welding tests are as shown in Table 4.

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

[Table 4]

As is clear from Tables 2 and 3, the evaluation of chip wear resistance was good or acceptable in the invention examples, but not in the comparative examples.

[0048]

EFFECTS OF THE INVENTION By using the welding wire of the present invention, in gas shielded arc welding of a thin steel plate using a welding robot, when the feed tip is used for a long time, the tip wear resistance is improved and good. Welded joints of various quality can be obtained.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshitaka Sasa             1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama             Shi) Kawasaki Steel Co., Ltd. Mizushima Steel Works (72) Inventor Kenji Toki             1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama             Shi) Kawasaki Steel Co., Ltd. Mizushima Steel Works F-term (reference) 4E084 BA22 CA25 CA27 DA33 GA02

Claims (3)

[Claims] 1. A steel wire for welding used in gas shielded arc welding, wherein C: 0.12 mass% or less, Si: 0.25 to.
1.5% by mass, Mn: 0.45 to 2.0% by mass, Ca: 0.0020% by mass
On the surface of the steel element wires containing the following, MoS _2: 10 to 70 wt%, K compound: 2 to 25 wt%, copper powder: the steel wires per 10kg of solid lubricant layer containing 70 wt% or less 0.2 ~ 1.0
g, and a lubricant layer comprising a fatty acid ester and / or a lubricating oil on the surface of the solid lubricant layer in an amount of 0.2 to 1.8 g per 10 kg of the steel wire, a steel wire for gas shield arc welding. 2. The coefficient A calculated from the following equation (1) using the Vickers hardness Hv of the steel wire and the cross-sectional area S (mm ² ) satisfies the range of 150 to 400. The steel wire for gas shielded arc welding according to claim 1, which is characterized in that. A = Hv × S (1) Hv: Vickers hardness of steel wire S: Cross-sectional area of steel wire (mm ² ) 3. The surface of the steel wire has an average thickness of 0.5 μm.
2. The above Cu plating layer is formed.
Alternatively, the steel wire for gas shielded arc welding according to item 2.