KR20190029472A - Multi-electrode gas-shielded arc welding method - Google Patents

Abstract

Provided is a multi-electrode gas-shielded arc welding method which has a low occurrence rate of blow holes and is excellent in melting point stability. The multi-electrode gas-shielded arc welding method comprises welding using a plurality of electrodes arranged in a line in a weld line direction, wherein the electrodes include a leading electrode and a filler wire located at the rear of the leading electrode. Moreover, the filler wire has electric resistance (R) per unit length at 25°C of 1.0 to 4.0 mΩ/cm, a feeding amount (WF) of 0.3 to 7.0 m/min, and a current (AF) of 30 to 250 A.

Description

[0001] MULTI-ELECTRODE GAS-SHIELDED ARC WELDING METHOD [0002]

This embodiment relates to a multi-electrode gas shielded arc welding method.

In order to improve the efficiency of horizontal fillet welding of conventional, shipbuilding or bridges, a one-round welding construction method in a multi-electrode gas shielded arc welding method has been adopted. However, in the case of actual structures, due to various disturbance factors [(a) excessive gap of fillet welds, (b) overcoat film thickness of shop primer, (c) As a result, the uniformity of the tongue gland, which is the point of these constructions, became unstable. As a result, arc instability occurred, and the correction welding increased due to the bundle of spatters, the bead shape, the deterioration of appearance and alignment, Particularly, the tendency becomes remarkable at a welding speed of about 1,500 to 2,000 mm / min. Therefore, even if the welding speed is increased, the modification ratio is increased, resulting in a problem that the number of welding processes is greatly increased.

Therefore, in Patent Document 1, a flux cored wire for gas shielded arc welding is used as a leading electrode and a trailing electrode, and a distance between the leading electrode and the trailing electrode is set to 15 to 50 mm, Electrode gas shielded arc welding method in which a molten metal between electrodes is inserted into a molten metal and a positive current is passed through the filler wire. Thus, even if a disturbance factor such as an excessive gap of the fillet weld, an overcoat film thickness of the shop primer, a current voltage fluctuation in the factory, or the like occurs in high speed welding at a welding speed of 2000 mm / min or more, , A multi-electrode gas-shielded arc welding method which does not require any modification can be obtained.

However, in the above method, there is an appropriate range of the deposition rate of the leading electrode and the trailing electrode and the filler wire. Especially when the deposition rate of the filler wire is not in the proper range, the bead appearance, the prevention of bead- However, sufficient characteristics can not necessarily be obtained from the point of view, and deterioration of porosity occurs due to these factors.

Therefore, in Patent Document 2, a flux cored wire for gas shielded arc welding is used as a leading electrode and a trailing electrode, and a distance between the leading electrode and the trailing electrode is set to 15 to 50 mm, Electrode gas shielded arc welding method comprising the steps of: inserting a current of a reverse polarity into a lead electrode between a pair of electrodes and flowing a current of a reverse polarity to the lead electrode and a lead electrode, (L / T) of the filler wire is 0.03 x (L + T), and the sum L + T of the deposition rate L (g / min) of the electrode and the deposition rate T ) To 0.3 x (L + T).

Japanese Patent No. 3759114 Japanese Patent Laid-Open No. 2008-55509

In multi-electrode gas-shielded arc welding, zinc vapor is generated from the steel sheet by arc heat. The zinc vapor penetrates through the molten metal or is partially blown into the molten metal, thereby generating pits or blowholes BH in the molten metal, leading to a decrease in the mechanical strength of the welded portion .

A lot of studies have been made on the generation of the blowholes with respect to the fusing paper, such as the change of the composition of the fusing paper or the stirring of the fusing paper. However, there are few studies on the method of reducing the generation of blowholes, there was. Also, in the above Patent Documents 1 and 2, the blowholes have not been studied.

Therefore, it is an object of the present invention to provide a multi-electrode gas-shielded arc welding method which is capable of reducing blowhole generation rate and also having excellent melting point stability.

As a result of intensive studies, the inventors of the present invention have found that, in a multi-electrode gas shielded arc welding method, by arranging filler wires behind a preceding electrode and limiting electric resistance and welding conditions of the filler wires to specific ones, And has excellent melt stability. Thus, the present invention has been accomplished.

In other words, an embodiment of the multi-electrode gas shielded arc welding method according to the present invention is a multi-electrode gas shielded arc welding method comprising welding using a plurality of electrodes arranged in a line in a weld line direction, Wherein the filler wire has an electric resistance (R) per unit length at 25 占 폚 of 1.0 to 4.0 m? / Cm, a feed amount (WF) of 0.3 to 1.0 m? / Cm, 7.0 m / min and a current (AF): 30 to 250 A.

(WF x AF) of the filler wire is R (m? / Cm), WF (m / min) and AF (A) / (10 x R)} < / = 30.

The filler wire may be a solid wire or a flux cored wire, and the filler wire may include C: 0 (including 0%) to 0.20 mass%, Si: 0 (Including 0%) to 2.0% by mass, and Mn: 0.3 to 3.0% by mass.

The welding current (A): 250 to 600 A, the arc voltage (V): 26 to 48 V, and the feed amount (W): (A), V (V), and W (m / min) of the electrodes other than the filler wire satisfy 110? X 10 < ⁴ > = 200.

One aspect of the multi-electrode gas shielded arc welding method according to the present invention is characterized in that the steel sheet of the welded material has a plate thickness of 6 to 40 mm.

One aspect of the multi-electrode gas shielded arc welding method according to the present invention is characterized in that the distance between the filler wire and the electrode positioned in front of the filler wire is 10 to 40 mm.

According to the present invention, the amount of the filler wire inserted into the melting paper can be customized by setting the electric resistance and the welding conditions of the filler wire under specific conditions. As a result, the blowhole occurrence rate is small, The multi-electrode gas shielded arc welding with excellent stability becomes possible.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional macro photograph for explaining a method of measuring a blowhole generation rate. FIG.
2 is a diagram for explaining a method of measuring the blowhole generation rate.

Hereinafter, embodiments for carrying out the present invention will be described in detail. The present invention is not limited to the embodiments described below. In this specification, " " representing the numerical range is used to mean that numerical values written before and after the numerical value are included as lower limit and upper limit.

A multi-electrode gas-shielded arc welding method according to the present embodiment (hereinafter occasionally referred to simply as "welding method") is a multi-electrode gas-shielded arc welding method in which a plurality of electrodes arranged in a row in a weld line direction are used , The plurality of electrodes includes a leading electrode and a filler wire located behind the leading electrode, and the filler wire has an electrical resistance (R) per unit length at 25 占 폚 of 1.0 to 4.0 m? / Cm, (WF): 0.3 to 7.0 m / min and current (AF): 30 to 250 A.

<Filler wire>

The filler wire in this embodiment is located behind the preceding pole. The number of electrodes may be two, or three or more, of the leading electrode and the filler wire. When the number of electrodes is three or more, at least the preceding pole, the filler wire, and the trailing pole are provided. However, the filler wire may be positioned forward or rearward of the trailing pole.

The filler wire was welded under the conditions that the electric resistance (R) per unit length at 25 占 폚 was 1.0 to 4.0 m? / Cm, the feeding amount (WF) was 0.3 to 7.0 m / min and the current (AF) do.

By satisfying such electric resistance, feeding amount and current range, it is possible to appropriately insert the filler wire into the melting paper and to discharge the zinc vapor generated from the zinc plating of the lower plate into the filler wire, Reduce.

Further, as a result of intensive studies, the present inventors have found that, in the high-speed horizontal fillet welding, the blowholes are about 1 to 2 mm larger than the root portion in inserting the filler wire into the melting zone. Further, it has been found that the blowhole generation rate can be reduced by inserting the filler wire to a position of about 1 to 2 mm in which the blowhole is easy to grow. The invention according to the present embodiment is based on such knowledge.

If the electric resistance R per unit length at 25 占 폚 (hereinafter sometimes simply referred to as "electric resistance") is less than 1.0 m? / Cm, the heat generation amount is small and the filler wire is inserted deeply into the fused paper, Excessive current (AF) is required. In addition, if the electric resistance exceeds 4.0 m? / Cm, the filler wire is easy to melt and the filler wire can not be inserted into the melting point.

Similarly, when the feed amount WF is more than 7.0 m / min, the filler wire is inserted deeply into the inside of the melting paper, and an excessive current (AF) is required. In addition, when the feeding amount is less than 0.3 m / min, the filler wire melts before achieving a sufficient filler wire insertion amount into the melting point.

If the current AF is less than 30A, the heat generation amount is small and the filler wire is inserted deeply into the inside of the melting paper, and an excessive electric resistance R is required. If the current is more than 250 A, the filler wire is easily melted and the filler wire can not be inserted into the melting paper.

The electric resistance R per unit length at 25 캜 of the filler wire is preferably 1.3 m? / Cm or more, more preferably 1.6 m? / Cm or more, and even more preferably 1.9 m? / Cm or more. Further, it is preferably 3.4 m? / Cm or less, more preferably 2.9 m? / Cm or less, even more preferably 2.4 m? / Cm or less.

The electrical resistance of the filler wire can be adjusted by the composition of the constituents of the filler wire. The electric resistance is an electric resistance value per unit length (unit: m? / Cm) measured by the four-terminal method at 25 占 폚.

The feeding amount WF of the filler wire is preferably 1.0 m / min or more, more preferably 2.0 m / min or more. It is preferably 6.0 m / min or less, more preferably 5.0 m / min or less.

The current AF of the filler wire is preferably 80 A or more, more preferably 100 A or more. It is preferably 170 A or less, more preferably 150 A or less.

The amount of inserting the filler wire into the fusing paper becomes an appropriate amount and the blowhole incidence rate is further reduced because the R (m? / Cm), WF (m / min) and AF WF x AF) / (10 x R)} (unit: (m 占 cm m) / (min 占))} is preferably 10 or more and 30 or less. The value represented by {(WF x AF) / (10 x R)} is more preferably 15 or more, and still more preferably 25 or less.

The filler wire is preferably a solid wire or a flux cored wire. When the filler wire is a solid wire or a flux cored wire, it preferably contains 0 to 0.20 mass% of C, 0 to 2.0 mass% of Si, and 0.3 to 3.0 mass% of Mn.

(C: 0 to 0.20% by mass)

C has the effect of improving the strength and toughness of the weld metal and also affects the spatter generated during welding. With respect to the spatter, although there is no problem even if the content of C is small, the lower limit is not particularly limited (it is not necessary to include it), but it is practically 0.01 mass% or more. In view of securing the strength and toughness of the weld metal, it is preferably 0.03 mass% or more.

On the other hand, when the amount of C is increased, the volume transfer is not stabilized and the amount of spatters generated increases. Therefore, the content of C is preferably 0.20 mass% or less, more preferably 0.10 mass% or less, and most preferably 0.08 mass% or less.

(Si: 0 to 2.0% by mass)

Si is a deoxidizing element and has the effect of ensuring the strength and toughness of the weld metal, and it is not necessary to contain it. However, it is preferably contained in an amount of 0.1 mass% or more, more preferably 0.3 mass% or more.

On the other hand, if a large amount of Si is contained, a large amount of slag may be generated during welding or the strength may increase excessively, which may lower the toughness of the weld metal. Therefore, the content thereof is preferably 2.0 mass% or less, more preferably 1.0 mass% And more preferably 0.8 mass% or less.

(Mn: 0.3 to 3.0% by mass)

Mn is effective as a deoxidizing agent and is an effective element for securing the strength and toughness of the weld metal. It is preferably contained in an amount of 0.3 mass% or more, more preferably 0.5 mass% or more, and further preferably 1.0 mass% or more .

On the other hand, when a large amount of Mn is contained, a large amount of slag is generated during welding or the strength is excessively increased, which may significantly lower the toughness of the weld metal. Therefore, the content thereof is preferably 3.0 mass% or less, more preferably 2.5 mass% And more preferably 2.0 mass% or less.

When the flux cored wire is used for the filler wire, the remainder is mainly composed of Fe, but the remainder may contain a flux cored wire which is usually used for gas shield arc welding. For example, in addition to the above components, a metal additive, an F compound, an arc stabilizer, and a slag forming agent may be added to the remainder. Others include inevitable impurities. When a solid wire is used for the filler wire, the remainder is Fe as the main component, but the remaining portion may contain other elements such as Ti, Ni, Cr, Al, Zr, and Mg.

When the filler wire is a flux cored wire, any structure of a seamless wire (seamless type) welded to the butt joint of the forced shell and a wire (core type) that does not weld the butt hole but leaves the gap intact . The outer surface of the shell may be plated with copper.

The wire diameter of the filler wire is not particularly limited, but is preferably 1.0 mm or more in view of welding workability. Further, from the viewpoint of welding workability, it is preferably 2.0 mm or less.

The filler wire preferably has a projection length (ET) of 15 to 35 mm. That is, by setting the protruding length ET to 15 mm or more, the heating value of the wire becomes appropriate, and the characteristics of the filler wire can be sufficiently exhibited. The projection length is more preferably not less than 17 mm, and more preferably not less than 19 mm. Further, by setting the projecting length to 35 mm or less, in addition to the appropriate amount of heating of the wire, the wire target property is also good, and the characteristics of the filler wire can be sufficiently exhibited. The projection length is more preferably not more than 33 mm, and further preferably not more than 31 mm.

The distance between the filler wire and the electrode positioned in front of the filler wire is preferably 10 to 40 mm. When the thickness is 10 mm or more, the filler wire can be inserted into the fused paper formed on the front electrode more preferably. If it is 40 mm or less, it is easy to insert the fused paper before the fused paper coagulates. The inter-pole distance is more preferably not less than 12 mm, and more preferably not more than 30 mm.

An electrode positioned in front of the filler wire indicates an electrode located closest to the filler wire among the electrodes positioned in front of the filler wire. For example, in the case of being positioned in the order of the leading pole-filler wire trailing pole, the distance between the leading pole and the filler wire indicates the distance between the leading pole and the filler wire. The distance between the wires.

<Previous performance>

The leading electrode in the present embodiment is not particularly limited as long as it is an electrode normally used for gas shielded arc welding.

The polarity of the leading electrode is preferably reverse polarity (DCEP), and is preferably a consumable electrode. That is, the flux cored wire is preferably a flux cored wire or a solid wire, more preferably a flux cored wire.

The flux cored wire is a wire filled with a flux in a forced shell showing a cylindrical shape, but the composition of the wire differs depending on the type of the welded material and the welding conditions, and is not particularly limited. Further, either the seamless type or the seam type can be used.

The composition of the solid wire also varies depending on the kind of the welded material and the welding conditions, and is not particularly limited.

As the flux cored wire of the preceding pole, for example, an Fe content of 80 to 95 mass% with respect to the whole wire can be used. Examples of the element that can be contained in the wire in addition to Fe include C, Mn, Ti, P, S, Ni, Si, Cr, Cu, Mo, Mg, B, F, Na, K, Nb, V, Zr, . These may be included in the case of being positively added and inevitable impurities, and may be included as a metal single crystal, an oxide, an alloy and the like. Specifically, the flux of the flux cored wire may include a slag forming agent, an arc stabilizer, a metal additive, and the like.

In addition, the solid wire is not limited, and as one example, it is preferable that the content of C is 0.01 to 0.18 mass%, Si is 0 to 1.00 mass%, Mn is 0.50 to 2.80 mass%, P is 0.030 mass% or less, S is 0.030 mass% or less , And Cu: 0.50 mass% or less, with the balance being Fe and inevitable impurities. Other metals such as Ti, Ni, Cr, Al, Zr, and Mg may be included.

The wire diameter of the flux cored wire or the solid wire of the preceding pole is not particularly limited, but is preferably 1.0 mm or more in view of welding workability. Further, from the viewpoint of welding workability, it is preferably 2.0 mm or less.

It is preferable that the leading electrode is the welding current (A): 250 to 600 A, the arc voltage (V): 26 to 48 V and the feeding amount (W): 5 to 20 m / ) And W (m / min) satisfy the relation of 110? [20 x W / (A x V) x 10 ⁴ ]? 200.

By setting the welding current (A) to 250 A or more, the heat input and the arc force become appropriate, and the penetration into the base material becomes sufficient, and good bead appearance, bead shape and bead alignment can be obtained. The welding current is more preferably 300 A or more, more preferably 350 A or more, and still more preferably 380 A or more. Further, by setting the welding current to 600 A or less, a good bead appearance, bead shape, and bead alignment without weld defect originating from undercut due to excessive arc force can be obtained. Further, since the amount of deposition is appropriate, defective fusing due to the leading edge of the melting edge and welding defect of slag inclusion can be prevented. The welding current is preferably 550 A or less, more preferably 500 A or less, and even more preferably 450 A or less.

The arc voltage (V) is preferably 26 V or more in view of arc stability, and more preferably 28 V or more. Further, it is preferable to set the voltage to 48V or less from the viewpoint of arc stability, and more preferably to 44V or less.

By setting the feed amount W to 5 m / min or more and 20 m / min or less, a weld bead having an appropriate welding amount can be obtained. The feed rate is more preferably 7 m / min or more, more preferably 9 m / min or more, and more preferably 10 m / min or more. The feed rate is more preferably 18 m / min or less, more preferably 16 m / min or less, and even more preferably 14 m / min or less.

The A (A), the V (V) and the W (m / min), [20 × {W / ( A × V)} × 10 4] { unit: (m) / (min · A · V )} Is 110 or more, the arc power, the arc spread and the deposition amount become optimum, the arc stability becomes good, and the spatter generation amount is reduced. In addition, good bead appearance, bead shape and bead alignment can be obtained, and therefore, 130 or more is more preferable. In addition, if the value of [20 x {W / (A x V)} x 10 ⁴ ] is 200 or less, the spread of the arc force and arc and the deposition amount become optimum, the arc stability becomes good and the amount of spatter generated is reduced. Further, since good bead appearance, bead shape and bead alignment can be obtained, it is more preferable to be 180 or less.

By setting the projecting length L of the wire to 15 mm or more, good arc stability can be obtained, and more preferably 20 mm or more. Further, by setting the projecting length to 35 mm or less, the wire target property becomes good and the bead alignment becomes good. Further, since excellent arc stability can be obtained, 30 mm or less is more preferable.

The shield gas used for welding at the leading electrode is not particularly limited. For example, Ar gas, carbon dioxide gas, a mixed gas of Ar gas and carbonic acid gas, or a mixed gas of Ar gas and oxygen gas can be used.

The flow rate of the gas is not particularly limited, but may be, for example, 15 to 30 L / min.

<Trailing electrode, other electrode>

The trailing and other electrodes in the present embodiment are preferably consecutive electrodes or lead electrodes connected to the leading and filler wires, and the polarity is preferably a consumable electrode with a positive polarity (DCEN). As the consumable electrode, a flux cored wire or a solid wire is preferably used, but more specifically, the same as that described in the above &lt; preceding electrode &gt;.

The preferred welding conditions for the trailing electrode or other electrode are the same as the preferred welding conditions for the preceding electrode described in the &lt; preceding electrode &gt;. For example, it is preferable that the welding current A is 250 to 600 A, the arc voltage V is 26 to 48 V and the feeding amount W is 5 to 20 m / ) And W (m / min) satisfy the relation of 110? [20 x W / (A x V) x 10 ⁴ ]? 200.

Other preferred embodiments of the protruding length, composition, wire diameter, shielding gas and the like are also the same as preferred embodiments of the preceding electrode.

<Welding conditions>

As described above, the gap between the filler wire and the electrode positioned in front of the filler wire is preferably 10 to 40 mm. When the thickness is 10 mm or more, the filler wire can be inserted into the fusing paper formed by the electrode located at the front side more satisfactorily. If it is 40 mm or less, it is easy to insert the fusing paper before the fusing paper coagulates. The inter-pole distance is more preferably not less than 12 mm, and more preferably not more than 30 mm.

When the electrode is located behind the filler wire, the gap between the filler wire and the electrode located at the back is preferably 10 to 40 mm. By setting the distance between the poles to 10 mm or more, welding can be performed while maintaining the effect of stabilizing the melting point by the filler wire, more preferably 12 mm or more. By setting the thickness to 40 mm or less, good bead shape, bead appearance and bead alignment can be obtained, and more preferably 30 mm or less.

The welding speed is preferably 800 to 2500 mm / min. By setting the welding speed to 800 mm / min or more, a good bead shape can be obtained without preceding the welding metal. The welding speed is more preferably 1000 mm / min or more.

By setting the welding speed to 2500 mm / min or less, good bead alignment can be obtained. The welding speed is more preferably 2000 mm / min or less, and more preferably 1500 mm / min or less.

The welding method according to the present embodiment is not particularly limited to the joint shape of the welded material, but it is preferably used for fillet welding, and more preferably used for horizontal fillet welding.

The size and shape of the welded material are not particularly limited. For example, a steel sheet having a thickness of 6 to 40 mm can be preferably used.

The welded material obtained by the welding method according to the present embodiment is obtained by, for example, putting a 2 mmV notch in a position 45 deg. From the root portion in a weld metal formed by horizontal fillet welding and observing the inside of the welded metal, , It is possible to carry out an evaluation of the weld defect. Here, the position of 45 DEG from the root portion means the surface of the weld metal at a position in the direction of 45 DEG from the intersection of the plane of the lower plate and the plane of the plate (see Figs. 1 and 2).

Here, FIG. 1 is a cross-sectional macro photograph for explaining the method of measuring the blowhole incidence rate, and FIG. 2 is a view for explaining a method of measuring the blowhole incidence rate.

1, it can be seen that the blow hole 1 is formed in a direction inclined at 45 degrees from the lower plate. In Fig. 2, it can be seen that a plurality of blow holes 1 extend vertically. In Fig. 2, the position indicated by the arrow A-A is the position where the face of the lower plate intersects the face of the plate of the welding plate at the time of welding.

The rate of occurrence of blowholes (BH), which are pore defects, among the weld defects can be evaluated by observing the fracture surface inside the weld metal. Specifically, the total BH width in the weld metal and the weld length are measured, and the value represented by (BH width total / weld length in the weld metal) can be regarded as the BH generation rate.

The BH generation rate is preferably 20% or less, more preferably less than 15%, more preferably less than 11%, even more preferably less than 7%, and particularly preferably 0% (no blowhole occurrence).

The stability of the melt paper can be visually judged by the insertion state of the filler wire into the melting paper. Specifically, it can be said that the filler wire is stably insertable to the inside of the melting paper, and that the stability of the melting paper is good if the melting paper is stable.

[Example]

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples, but it is possible to carry out the present invention in a range that is suitable for the purpose of the present invention. And are included in the technical scope of the present invention.

&Lt; Examples 1 to 22 and Comparative Examples 1 to 6 &gt;

Electrode gas shielded arc welding (horizontal fillet welding) was performed using the leading electrode and the filler wire under the conditions shown in Tables 1 and 2.

The filler wire is made of a solid wire according to JIS Z 3312: 2009 or a metal-based flux cored wire according to JIS Z 3313: 2009, which contains at least the amount of C, Si and Mn (mass% The polarity of the electrode is positive (DCEN) and the wire diameter is 1.2 mm. The electrical resistance (R) per unit length is a value measured by the four-terminal method at 25 占 폚.

Metal flux cored wires conforming to JIS Z 3313: 2009 are used for the leading electrode. The polarity of the electrode is DCEP and the wire diameter is 1.6 mm. Carbon dioxide gas was used as the shield gas and the flow rate was 25 L / min.

The welded material is a steel sheet conforming to JIS G 3106: 2015 SM490A for both the bottom plate and the bottom plate, and the plate thickness is as shown in Table 2. The thickness of the primer on the surface of the steel sheet was 30 μm. The welding speed was set at 1000 to 1500 mm / min.

[Table 1]

[Table 2]

<Evaluation>

Evaluation of the stability of the blowhole and the melting point was carried out for welds at the time of welding and after welding. Details of each evaluation are as follows, and the results are shown in Table 3.

(Blowhole (BH) occurrence rate)

By the method described in the above-mentioned embodiment, a value appearing as the BH width total / weld length in the weld metal for the welded article after welding is obtained as the BH occurrence rate. In this embodiment, the blowhole occurrence rate at a position 3 mm away from the position of the arrow A-A shown in Fig. 2 was evaluated. In Table 3, a BH incidence rate of 0 to 6%, a BH incidence rate of 7 to 10%, a BH incidence rate of 11 to 14%, a BH incidence rate of? +, A BH incidence rate of? Is 15 to 20%, and &quot; x &quot; means that the BH generation rate exceeds 20%.

(Melting point stability)

The inserting condition of the filler wire into the melting paper at the time of welding was visually judged and evaluated. In Table 3, "○" indicates that the melting point stability is stably inserted and the melting point is in a stable state, and "x" indicates that the inserting state of the filler wire is unstable or not inserted into the melting paper.

[Table 3]

Regarding the melting point stability, in Comparative Examples 1, 2 and 4, no filler wire was inserted into the melting paper. Further, in Comparative Example 3, the filler wire was inserted into the melting paper, but was not melted in the melting paper and became unstable. In Comparative Example 5, arc was generated from the filler wire, and the filler wire was not inserted into the melting paper. In Comparative Example 6, the result was that the heat of the melting paper was lost before the filler wire was inserted into the melting paper due to insufficient heat generation.

From the above results, it was found that, in the welding method according to the present embodiment, the blowhole generation rate is low and the melting point stability is also excellent because the electric resistance, feeding amount, and current of the filler wire are within a predetermined range.

Further, the blowhole occurrence rate was further reduced by satisfying the relationship of 10? {(WF x AF) / (10 x R)}? 30 in the electric resistance, feeding amount and current of the filler wire.

Claims (7)

A multi-electrode gas-shielded arc welding method comprising welding a plurality of electrodes arranged in a line in a weld line direction,
Wherein the plurality of electrodes include a leading electrode and a filler wire located behind the leading electrode,
The filler wire preferably has an electric resistance (R) of 1.0 to 4.0 m? / Cm per unit length at 25 占 폚, a feeding amount (WF) of 0.3 to 7.0 m / min and a current
Multi - electrode gas shield arc welding method. The method according to claim 1,
The R (m? / Cm), the WF (m / min) and the AF (A) of the filler wire satisfy the relationship 10? {(WF x AF) / (10 x R)}? 30
Multi - electrode gas shield arc welding method. The method according to claim 1 or 2,
The filler wire is a solid wire or a flux cored wire,
Also, the filler wire preferably contains 0.20 mass% of C: 0 (including 0%), 2.0 mass% of Si (including 0%), and 0.3: 3.0 mass% of Mn
Multi - electrode gas shield arc welding method. The method according to claim 1 or 2,
The electrode other than the filler wire has a welding current (A) of 250 to 600 A, an arc voltage (V) of 26 to 48 V and a feeding amount (W) of 5 to 20 m /
The A (A), the V (V) and the W (m / min) of the electrodes other than the filler wire satisfy the relationship of 110? [20 x W / (A x V) x 10 ^4? Satisfy the relationship
Multi - electrode gas shield arc welding method. The method according to claim 1 or 2,
Plate thickness of welded steel plate: 6 ~ 40mm
Multi - electrode gas shield arc welding method. The method according to claim 1 or 2,
The distance between the filler wire and the electrode located in front of the filler wire: 10 to 40 mm
Multi - electrode gas shield arc welding method. The method of claim 4,
The distance between the filler wire and the electrode located in front of the filler wire: 10 to 40 mm
Multi - electrode gas shield arc welding method.

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