JP2015205280A - Two-electrode horizontal fillet gas shield arc-welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-electrode horizontal fillet gas shield arc-welding method that stabilizes an arc state with little sputter by the horizontal fillet gas shield arc-welding for a plank, improves slag encapsulating performance, slag removability, and bead shape, efficiently yields a long-leg fillet welded part with each uniform leg length free of welding defects, and is excellent in porosity resistance even in welding a primer-coated steel plate.SOLUTION: A welding solid wire is used for a preceding electrode, and a welding flux-cored wire is used for a following electrode to set an interelectrode distance between the preceding electrode and the following electrode to 50 mm or more, a torch angle of the preceding electrode and that of the following electrode to 40-60°,a wire aiming position of the preceding electrode to 5-10 mm on the lower plate side from the route part, a wire aiming position of the following electrode to 3-7 mm on the upper plate side from the route part, and a wire diameter of the preceding electrode and that of the following electrode to 1.2-2.0 mm.

Description

  In the production of steel structures such as shipbuilding, steel frames, bridges, etc., the present invention has a large leg length fillet bead having a good bead shape and no defects in the welded portion, particularly when performing horizontal fillet gas shielded arc welding of thick plate members. In addition, the present invention relates to a two-electrode horizontal fillet gas shielded arc welding method suitable for improving pore resistance in horizontal fillet gas shielded arc welding using a primer-coated steel sheet.

  In recent years, in the production of various welded structures, the gas shielded arc welding method can improve the welding efficiency, so that its application is increasing. Especially in structures such as shipbuilding, steel frames and bridges, the ratio of fillet welding is large, and in the case of horizontal fillet welding with a plate thickness of 30 mm or more, the leg length of the fillet weld is required to be 8 mm or more. Therefore, a two-electrode horizontal fillet gas shielded arc welding method using a flux-cored wire for welding has been applied for the purpose of improving efficiency. For example, Patent Document 1 and Patent Document 2 disclose a horizontal fillet gas shield arc welding method using two electrodes.

  However, these welding methods are intended to increase the speed in the case of a long member with a leg length of 4 to 6 mm, and the weld bead is formed by a two-electrode one-pool method in which the molten pool generated at each electrode is combined. Therefore, in the case of a plate thickness of 30 mm or more where a leg length of the fillet welded portion is required to be a large leg length of 8 mm or more, it is difficult to sufficiently satisfy the quality requirement.

  On the other hand, as a technique for obtaining a fillet weld portion having a large leg length by the composition of the flux-cored wire for welding, Patent Document 3 and Patent Document 4 both obtain a large leg length of 10 mm by one-pass welding by one-electrode welding. Flux-cored wires for welding have been proposed. However, even if horizontal fillet welding is performed using these flux-cored wires for welding, if the leg length exceeds 10 mm, the root portion will not be sufficiently melted, slag will be caught near the root portion, and the upper plate will be undercut. It becomes easy to do.

  In recent years, for the purpose of rust resistance, many steel plates with a primer coated on the surface of the steel plate are used, but when such a primer coated steel plate is welded, the primer and the steel plate coated on the vertical plate and the lower plate are used. Since red rust on the surface and adhering moisture are vaporized during welding and steam gas is generated, pits are generated, and this rework welding takes time, and thus there is a problem that production costs increase.

  As a method for solving these problems, Patent Document 5 limits the components of the flux-cored wire for welding used for the leading electrode and the trailing electrode in horizontal fillet gas shielded arc welding in the two-electrode one-pool method. Discloses a method for improving the porosity resistance when a primer-coated steel sheet is used. However, since the welding method disclosed in Patent Document 5 relates to horizontal fillet welding in the two-electrode one-pool method, even if the pore resistance can be improved, the leg length is 8 mm or more. In the horizontal fillet gas shielded arc welding, there is a problem that an undercut or an overlap is likely to occur in the fillet welded portion.

JP-A-2-280968 JP-A-6-234075 JP-A-4-300091 Japanese Patent Application Laid-Open No. 7-328795 JP 2009-190042 A

  Therefore, the present invention has been devised in view of the above-described problems, and in a two-electrode horizontal fillet gas shielded arc welding of a thick plate, the arc state is good, the amount of spatter generation is small, and the slag encapsulation is achieved. Also, a fillet welded part with a large leg length is obtained with high efficiency, with a good bead shape, no bead defects such as slag entrainment and lack of penetration, etc. It is an object of the present invention to provide a two-electrode horizontal fillet gas shielded arc welding method which is excellent in both horizontal fillet gas shielded arc welding using metal and is resistant to porosity.

  The gist of the present invention is that in a two-electrode horizontal fillet gas shielded arc welding method, a solid wire for welding is used for the leading electrode, a flux-cored wire for welding is used for the trailing electrode, and the distance between the leading electrode and the trailing electrode is set. 50 mm or more, the torch angle of the leading electrode and the trailing electrode with respect to the lower plate is 40 to 60 °, the aiming position of the leading electrode wire is 5 to 10 mm from the root portion to the lower plate side, and the aiming position of the trailing electrode wire is the root 3 to 7 mm from the part to the upper plate side, and the wire diameters of the leading electrode and the trailing electrode are 1.2 to 2.0 mm.

  Moreover, the said flux-cored wire for welding is the mass% with respect to the total mass of a wire, contains 3.5-8.5% of the sum total of a slag formation agent in a flux, and the remainder is iron powder, alloy powder, and an unavoidable impurity. The two-electrode horizontal fillet gas shield arc welding method is also characterized.

  According to the two-electrode horizontal fillet gas shielded arc welding method of the present invention, in the horizontal fillet gas shielded arc welding of thick plates, the arc state is good, the amount of spatter is small, slag encapsulation and slag peelability , Good bead shape, uniform fillet bead with large leg length with uniform leg length without weld defects such as slag entrainment or lack of penetration in fillet welds, and using primer coated steel plate Even in this case, the pore resistance is excellent, and the welding efficiency can be improved and a high-quality weld can be provided.

It is a schematic diagram which shows arrangement | positioning of each electrode in the horizontal fillet gas shield arc welding method by the 2 electrode 2 pool system of this invention. It is sectional drawing of the fillet weld part welded by the horizontal fillet gas shield arc welding method by the 2 electrode 2 pool system of this invention.

  In order to solve the above-mentioned problems, the present inventors have studied welding conditions for fillet gas shielded arc welding using a two-electrode, two-pool method.

FIG. 1 shows a two-electrode two-pool horizontal fillet gas shielded arc welding according to the present invention, a preceding electrode T that is welded in advance in the welding direction, and a subsequent welding to the preceding electrode T. It is a schematic diagram which shows arrangement | positioning of the trailing electrode L, (a) is the sectional drawing, (b) is a side view, (c) is a perspective view. Moreover, FIG. 2 shows the cross-sectional shape of the fillet welded part obtained by the horizontal fillet gas shield arc welding method in the two-electrode two-pool system of the present invention. As shown in FIGS. 1 (a) and 1 (b), horizontal fillet gas shielded arc welding of the two-electrode two-pool method is performed at a corner of a member in which the lower plate 1 and the upper plate 2 are assembled in a T shape or L shape. Gas shield arc welding is simultaneously performed with the leading electrode L and the trailing electrode T on the root portion 3 corresponding to the portion. At this time, in the gas shielded arc welding method according to the present invention, as shown in FIG. 1 (c), the molten pool 4 of the leading electrode L and the molten pool 5 of the trailing electrode T are separately formed and welded in a two-pool state. I do. For the purpose of obtaining a stable arc state and an excellent bead shape of the fillet weld, the welding torch of the leading electrode L and the trailing electrode T is orthogonal to the welding progress direction as shown in FIG. Welding is performed with an inclination (hereinafter referred to as torch angle θ ₁ ) provided in the direction. The reference direction in the torch angle θ ₁ is the horizontal direction. Further, with respect to the direction parallel to the welding direction, as shown in FIG. 1 (b), the leading electrode L has an inclination from the vertical direction to the rear (hereinafter referred to as receding angle θ ₂ ), and the trailing electrode T Is welded in a state where an inclination from the vertical direction to the front (hereinafter, advancing angle θ ₃ ) is provided. The reference direction for the receding angle θ ₂ and the advancing angle θ ₃ is the vertical direction.

  In this welding method, a flux-cored wire for welding is usually used for both electrodes. However, in the case of horizontal fillet gas shielded arc welding of thick plates, the leg length of the fillet weld is required to be 8 mm or more. When horizontal fillet gas shielded arc welding is performed using the 2-electrode 2-pool method, the arc force of the welding flux-cored wire used for the leading electrode L is weaker than that of the solid wire for welding, and there are many slags to be included. It is difficult to completely melt the portion, and poor penetration and slag entrainment are likely to occur. Further, as shown in FIG. 1 (c), since it is necessary to separately form the molten pool 4 of the leading electrode L and the molten pool 5 of the trailing electrode, the gas in the two-electrode two-pool system in a large current region In shielded arc welding, it is difficult to adjust the welding conditions such as the distance D between the leading electrode L and the trailing electrode T, the wire aiming positions of the leading electrode L and the trailing electrode T, and the leg length of the fillet weld is uneven. Or undercuts or overlaps, and the bead shape is often poor.

  In the horizontal fillet welding by the two-electrode two-pool method, the present inventors have formed after the leading electrode bead 10 formed by the leading electrode L and the trailing electrode T as shown in FIG. As a result of various studies to obtain a fillet welded portion in which the row electrode beads 11 are well balanced, the lower plate leg length S1 is equal to the upper plate leg length S2, and a large leg length is obtained, a solid wire for welding is applied to the leading electrode L. By using a welding flux-cored wire for the trailing electrode T and defining the total amount of the slag forming agent of the welding flux-cored wire for the trailing electrode T, the solid wire for welding the leading electrode L has a large leg length. Ensuring the amount of welding necessary to form the meat weld, and uniformly encapsulating the molten pool surface of the trailing electrode T with molten slag with the flux-cored wire for welding the trailing electrode T, and the leg length of 8 mm or more Good even with large leg length It found that lugs peelability and slag encapsulated is obtained.

Further, as shown in FIGS. 1A and 1B, the gap D in the welding progress direction of the leading electrode L and the trailing electrode T is defined, and the lower plate of the leading electrode L from the root portion 3 is defined. The distance of the target position of the wire 20 on the side (hereinafter referred to as the “wire target position”) is A, and the target position of the wire 30 on the upper plate 1 side of the trailing electrode T from the root portion 3 (hereinafter referred to as the “wire target position”). And the torch angle θ ₁ of the leading electrode L and the trailing electrode T is defined, the arc state is stabilized, there is no overlap, undercut, poor penetration and slag entrainment, and the leg length is 8 mm or more. It was found that a fillet welded portion having a lower leg length S1 and an upper board leg length S2 with the same large leg length was obtained.

  It has also been found that since the arc force generated from the welding solid wire of the leading electrode L is strong, the molten pool of the leading electrode L is agitated to release the vapor gas, thereby suppressing the generation of pits.

  The reasons for limiting the construction conditions of the two-electrode horizontal fillet gas shield arc welding method in the present invention will be described below.

[Use welding solid wire for leading electrode and welding flux-cored wire for trailing electrode]
When a solid wire for welding is used for the leading electrode L in horizontal fillet gas shielded arc welding in the two-electrode two-pool method, the leading electrode L and the trailing electrode T are both preceded by using a flux-cored wire for welding. Since the arc force from the welding solid wire of the electrode L is strong, the root portion can be sufficiently melted at the time of welding, and the amount of slag is also small, so that poor penetration of the fillet weld and slag entrainment can be suppressed. . Further, since the welding solid wire of the leading electrode L has a larger amount of welding than the flux-cored wire for welding, it is possible to secure a sufficient amount of welding for obtaining a fillet weld portion having a large leg length of 8 mm or more. A bead shape can be obtained. Further, since the flux-cored wire for welding is used for the trailing electrode T, the surface of the molten pool 5 of the trailing electrode T can be uniformly encapsulated with molten slag, and the slag encapsulation and slag peelability should be improved. Can do.

  Furthermore, when horizontal fillet gas shielded arc welding is performed using a primer-coated steel sheet in a two-electrode, two-pool system, the molten pool of the leading electrode L is agitated and the vapor gas generated from the primer-coated steel sheet is released to the outside. Pit can also be reduced.

  On the other hand, when using the flux-cored wire for welding for both the leading electrode and L and the trailing electrode T, since the arc force of the leading electrode L is weaker than the solid wire for welding, the molten pool of the leading electrode L is not sufficiently stirred, The occurrence of pits cannot be suppressed sufficiently. Further, when the welding amount of the leading electrode L is increased, as shown in FIG. 2B, slag entrainment 7 in the root portion 3 is likely to occur.

  When the welding solid wire is used for both the leading electrode L and the trailing electrode T, the arc force of the trailing electrode T is also strong, so that the bead surface of the fillet weld becomes convex and the bead shape becomes poor. Further, since the slag forming agent supplied from both electrodes is extremely small, the molten slag cannot encapsulate the entire molten pool of the trailing electrode T, and cannot support the drooping of the weld bead. In addition to being uniform, the slag encapsulation and slag peelability are also poor.

  In addition, when a flux-cored wire for welding is used for the leading electrode L and a solid wire for welding is used for the trailing electrode T, the solid electrode for welding is used for the trailing electrode T that functions to adjust the bead shape. The arc from the electrode T is strong, the bead surface of the fillet weld is convex, and the bead shape is poor. Further, since the molten slag cannot be encapsulated uniformly over the entire molten pool 5 of the trailing electrode T, the leg length of the fillet welded portion is also uneven, and the slag encapsulation and slag peelability are poor.

  Therefore, a solid wire for welding is used for the leading electrode L, and a flux-cored wire for welding is used for the trailing electrode T.

[Distance between leading electrode and trailing electrode: 50 mm or more]
In order to obtain a fillet weld with a large leg length by horizontal fillet gas shielded arc welding in the two-electrode two-pool system shown in FIG. 1 (a), the leading electrode shown in FIG. 1 (b) and FIG. 1 (c) It is necessary to make the inter-electrode distance D between L and the trailing electrode T appropriate. When the inter-electrode distance D between the leading electrode L and the trailing electrode T is less than 50 mm, the molten pool 5 of the trailing electrode T is generated in a state where the molten pool 4 of the leading electrode L is not solidified, and these molten pools are It overlaps and becomes a one pool state, an overlap occurs at the bottom plate 1 side toe portion of the fillet welded portion, and an undercut occurs at the top plate 2 side toe portion, resulting in a poor bead shape. Therefore, the interelectrode distance D between the leading electrode L and the trailing electrode T is set to 50 mm or more. The upper limit of the inter-electrode distance D between the leading electrode L and the trailing electrode T is not particularly limited, but is preferably 200 mm or less from the viewpoint of ease of welding work and the size of the welding apparatus.

[Torch angle with respect to lower plate of leading electrode and trailing electrode: 40-60 °]
In the horizontal fillet gas shielded arc welding in the two-electrode two-pool system shown in FIG. 1A, if the torch angle θ ₁ with respect to the lower plate 1 of the leading electrode L and the trailing electrode T is less than 40 °, the arc Too close to the lower plate 1 makes the arc state unstable, resulting in frequent spattering. Further, as shown in FIG. 2 (c), an undercut 8 is generated at the bottom plate 1 side toe of the fillet welded portion, resulting in a poor bead shape, and the lower plate leg length S1 is reduced to reduce the leg length. Become even. On the other hand, when the torch angle θ ₁ with respect to the lower plate 1 of the leading electrode L and the trailing electrode T exceeds 60 °, the arc becomes too close to the upper plate 2 and the arc state becomes unstable, resulting in frequent spattering. Furthermore, an overlap occurs at the bottom plate 1 side toe of the fillet weld and an undercut occurs at the top plate 2 side toe, resulting in a poor bead shape. The top plate leg length S2 is also reduced and the leg length is reduced. Become unequal. Therefore, the torch angle θ _{1 with} respect to the lower plate 1 of the leading electrode L and the trailing electrode T is 40 ° to 60 °.

[Target position of the leading electrode is 5-10mm from the root to the lower plate]
The target position of the wire toward the lower plate 1 side of the preceding electrode L is an intersection of the lower plate 1 and a substantially extended line of the wire 20 in the preceding electrode L. When the distance A between the wire aiming position on the lower plate 1 side of the preceding electrode L shown in FIG. 1A and the root portion 3 is less than 5 mm, the leading electrode L is formed as shown in FIG. Since the leading electrode bead 10 thus formed is completely melted and covered by the trailing electrode bead 11, the lower plate leg length S1 is reduced, and the familiarity of the bottom plate 1 side toe portion of the fillet welded portion is deteriorated. A wrap 9 is generated, and the bead shape becomes poor. On the other hand, when the distance A between the wire aiming position on the lower plate 1 side of the leading electrode L and the root portion 3 exceeds 10 mm, as shown in FIG. 2 (e), the leading electrode bead 10 and the trailing electrode bead 11 The bead shape is poor, the upper plate leg length S2 is reduced, and a leg length of 8 mm or more cannot be obtained. Further, since the wire aiming position of the leading electrode L is too far from the root portion 3, the arc of the trailing electrode L cannot completely melt the root portion 3, and a penetration defect 6 occurs in the root portion 3. Therefore, the target position of the leading electrode L is set to 5 to 10 mm from the root portion 3 to the lower plate 1 side.

[The target position of the trailing electrode is 3 to 7 mm from the root part to the upper plate side]
The target position of the wire toward the upper plate 2 side of the trailing electrode T is an intersection of the lower plate 1 and the substantially extended line of the wire 30 in the trailing electrode T. If the distance B between the wire aiming position of the succeeding electrode T shown in FIG. 1A toward the upper plate 2 side and the root portion 3 is less than 3 mm, the upper plate leg length S2 is reduced. Moreover, as shown in FIG.2 (d), the overlap 9 arises in the lower plate 1 side toe part of a fillet weld part, and a bead shape becomes bad. On the other hand, when the distance B between the wire aiming position on the upper plate 2 side of the trailing electrode T and the root portion 3 exceeds 7 mm, as shown in FIG. Undercut 8 occurs in the part, and the bead shape becomes poor. Further, there is little overlap between the leading electrode bead 10 and the trailing electrode bead 11, and the bead shape becomes poor. Therefore, the target position of the trailing electrode T is set to 3 to 7 mm from the root portion 3 to the upper plate 2 side.

[Wire diameter of leading electrode and trailing electrode: 1.2 to 2.0 mm]
As for the wire diameters of the wires 20 and 30 of the leading electrode L and the trailing electrode T, it is necessary to select a wire diameter suitable for a large leg length of 8 mm or more of the fillet weld and a welding speed. If the wire diameters of the wires 20 and 30 of the leading electrode L and the trailing electrode T are less than 1.2 mm, the wire feeding speed is close to the upper limit in order to secure a fillet weld with a large leg length of 8 mm or more. The arc state becomes unstable, spattering occurs frequently, and the bead shape becomes poor. On the other hand, if the wire diameters of the leading electrode L and the trailing electrode T exceed 2.0 mm, the wire cannot be fed with a normal wire feeding device, and a dedicated wire feeding device must be installed. Cost increases. Therefore, the wire diameter of the leading electrode and the trailing electrode is set to 1.2 to 2.0 mm.

[Total slag forming agent: 3.5 to 8.5%]
By performing horizontal fillet gas shielded arc welding with the 2-electrode 2-pool method under the above-mentioned construction conditions, the arc state is stable, spatter and pits are less likely to occur, slag encapsulation and slag peelability are good, It is possible to obtain a welded bead having a uniform large leg length without undercuts or overlaps, thereby achieving high welding efficiency. On the other hand, in the case of horizontal fillet gas shielded arc welding with thick plates, the amount of slag forming agent for welding flux-cored wire used for the trailing electrode T in order to further improve the bead shape, slag encapsulation and slag peelability Need to be limited.

  The slag forming agent of the flux-cored wire for welding used for the trailing electrode T becomes a molten slag when forming a fillet welded part by horizontal fillet gas shield arc welding in the two-electrode two-pool method, and the trailing electrode T The entire weld pool is encapsulated and the bead shape of the fillet weld is adjusted, and the melted metal is prevented from flowing to the lower plate. The leg length of the fillet weld is even with a large leg length of 8 mm or more. Has the effect of If the total amount of the slag forming agent is less than 3.5% by mass with respect to the total mass of the wire, the slag generation amount is insufficient and the entire molten pool of the trailing electrode T cannot be encapsulated uniformly, so the bead shape is poor. At the same time, the molten slag is baked on the bead surface, and the slag peelability is poor. On the other hand, if the total amount of the slag forming agent exceeds 8.5% by mass, the slag is encapsulated and unevenness occurs in the slag encapsulated state, resulting in a poor bead shape. Therefore, the total amount of the slag forming agent is set to 3.5 to 8.5% by mass with respect to the total mass of the wire.

The slag forming agent includes TiO ₂ , SiO ₂ , ZrO ₂ , Na ₂ O, K ₂ O, Al ₂ O ₃ , FeO, Fe ₂ O ₃ , MgO and other oxides and CaF ₂ , K ₂ SiF ₆ , This refers to the total of fluorides such as Na ₃ AlF ₆ .

  The reason for limiting the constituent components of the flux-cored wire for welding used in the trailing electrode T of the present invention has been described above, the balance being steel outer shell components C, Si, Mn, Fe, inevitable impurities, iron in the flux Powders, alloy powders and inevitable impurities. An appropriate amount of iron powder can be added for the purpose of increasing the welding speed. Further, the alloy powder refers to metal powder such as Si, Mn, Ti, Al, Mg, and iron alloy powder such as Fe-Si, Fe-Mn, Fe-Si-Mn, Fe-Al, Fe-Ti, and the like. An appropriate amount can be added for the purpose of improving the mechanical properties of the weld metal.

  The steel outer shell is a hot-rolled steel strip having excellent wire drawing workability after flux filling, and is C: 0.10% or less, Si: 0.05% or less, Mn: 0.20 to 0.80%, P: 0.050% or less, S: 0.050% or less are suitable, and in particular, C is 0.005 to 0.03. % Is also effective for reducing spatter and reducing fume.

  The cross-sectional shape of the flux-cored wire for welding may be either a caulking type or a seamless type, but the seamless type that can be plated with copper on the wire surface has less wear on the tip and a longer stable arc state. The time can be maintained, and the efficiency of welding can be improved. Moreover, since there is no seam in a wire, it is excellent in hygroscopicity and can be stored for a long time.

  Furthermore, the hydrogen content and the nitrogen content in the flux-cored wire for welding are desirably 40 ppm or less with respect to the total mass of the wire in order to prevent deterioration of the pore resistance and impact toughness.

  In addition, it is effective to intentionally add S as a slag remover in the form of FeS or the like, but if S exceeds 0.030% by mass with respect to the total mass of the wire, the slag encapsulation is poor. Thus, the bead shape becomes defective.

The shielding gas is usually CO ₂ because it is economical, but a mixed gas of Ar and CO ₂ can also be used.

  Hereinafter, the present invention will be described more specifically with reference to examples.

  Hot rolled steel strip with mild steel skin (C: 0.02 mass%, Si: 0.01 mass%, Mn: 0.35 mass%, Al: 0.02 mass%, N: 0.0015 mass%) After filling various fluxes composed of the content of the slag forming agent shown in Table 1 at a flux filling rate of 17% by mass, forming a mild steel shell into a pipe shape and welding the end faces together to form a seamless shape, Table 3 Various types of welding flux-cored wires reduced in diameter to the various wire diameters shown were made.

The welding flux-cored wire shown in Table 1 is used for the trailing electrode, the welding electrode shown in Table 2 is used for the leading electrode, and the welding is performed in the 2-electrode 2-pool system under the various welding conditions shown in Table 3. Fillet gas shielded arc welding (simultaneous welding on both sides of one pass) was performed to investigate welding workability. The distance between the tip base materials was 25 to 30 mm, CO ₂ gas was used as the shielding gas, welding was performed at a gas flow rate of 25 liters / min and a welding length of 750 mm.

The specimen is a steel plate with a primer applied to the surface of a 490 N / mm ² grade high-strength steel (hereinafter referred to as a primer steel plate. The primer film thickness is about 15 μm on the side surface, the end surface is milled, the steel plate dimensions: plate width 100 mm × length 1000 mm × A plate having a thickness of 32 mm and assembled in a T shape with no gap between the lower plate and the upper plate was used.

  T-shaped test specimens are produced by horizontal fillet gas shielded arc welding using a 2-electrode 2-pool system. Arc stability, spatter generation, slag encapsulation, slag peelability, number of pits, and bead shape of each prototype wire The leg length (measured value) was investigated and evaluated. Regarding the arc stability, slag encapsulation, slag peelability, and bead shape, it was confirmed by visual observation whether or not they were good. Further, the amount of spatter generation was confirmed by visual observation, and the amount of pit generation was checked for the presence or absence of pit generation, and the number of pits was measured. Regarding the leg length, both the lower plate leg length S1 and the upper plate leg length S2 are 8 mm or more in length, and in accordance with JIS Z 3313, the leg length difference of each leg length is 0.5 × Smin (the lower plate leg length S1 and the upper plate leg length S2 (Minimum value) -0.5 or less were regarded as equal and accepted. The results are summarized in Table 4.

  Table 3, Table 4, middle No. 1-7 are examples of the present invention, No.1. 8 to 20 are comparative examples.

  No. which is an example of the present invention. 1-5 is a solid wire for welding as a leading electrode, a flux-cored wire for welding as a trailing electrode, a distance between electrodes of the leading electrode and the trailing electrode, a torch angle with respect to the lower plate of the leading electrode and the trailing electrode, Since the target electrode with respect to the lower plate and the upper plate of the preceding electrode and the succeeding electrode, the wire diameter of the preceding electrode and the succeeding electrode are appropriate, and the content of the slag forming agent in the welding flux-cored wire rack is appropriate. , Good arc condition in horizontal fillet gas shielded arc welding with 2-electrode 2-pool system with primer coated thick steel plate, less spatter generation, bead shape, slag encapsulation and slag peelability It was good, no pits were produced, and a fillet welded part having a uniform large leg length with both leg lengths of 8 mm or more could be obtained, which was a very good result.

  In addition, No. No. 6, since the total flux forming agent of the welding flux-cored wire (symbol F5) used for the trailing electrode was less than 3.5%, the slag encapsulation and slag peelability and the bead shape were slightly poor. However, there was no problem with the quality of the fillet weld. No. No. 7, the total flux forming agent of the welding flux-cored wire (symbol F6) used for the trailing electrode was over 8.5%, so the slag encapsulation and bead shape were somewhat poor. There was no problem with the quality of the weld.

  No. in the comparative examples. In No. 8, since the flux-cored wire for welding (symbol F2) was used for both the leading electrode and the trailing electrode, slag entrainment occurred in the root portion of the fillet welded portion, and pits were generated due to poor porosity resistance. .

  No. No. 9 used a flux-cored wire for welding as the leading electrode and a solid wire for welding as the trailing electrode, so that the slag encapsulation and slag peelability and the bead shape were poor. Moreover, the leg length of the fillet weld was also uneven.

  No. No. 10 used welding solid wires for both the leading electrode and the trailing electrode, so the slag encapsulation and slag peelability and the bead shape were poor, and the leg length of the fillet weld was also uneven.

  No. 11, because the wire diameters of the leading electrode and the trailing electrode exceed 2.0 mm, the wire cannot be fed by a normal wire feeding device, and a dedicated wire feeding device is installed. it was high. Moreover, since the sum total of the slag formation agent of the flux-cored wire for welding (symbol F6) used for the succeeding electrode is more than 8.5%, the slag encapsulation property and the bead shape were poor.

  No. In No. 12, since the distance between the leading electrode and the trailing electrode was less than 50 mm and short, the arc state was unstable and the amount of spatter was large. In addition, an overlap occurred at the bottom plate side toe portion of the fillet welded portion, and an undercut occurred at the top plate side toe portion, and the bead shape was poor.

  No. In No. 13, the distance between the target position of the wire on the lower plate side of the preceding electrode and the root portion was longer than 10 mm, so that a poor penetration occurred in the root of the fillet welded portion, and the bead shape was also poor. Further, the upper plate leg length of the fillet welded portion was small, and the leg length was uneven.

  No. No. 14, the distance between the wire target position on the lower plate side of the preceding electrode and the root portion is less than 5 mm and is short, so that overlap occurs at the bottom plate side toe portion of the fillet welded portion and the bead shape is poor. It was. Moreover, the lower plate leg length of the fillet welded portion was small, and the leg length was uneven.

  No. No. 15, the distance between the wire target position on the upper plate side of the trailing electrode and the root portion is longer than 7 mm, and therefore, the undercut 6 occurs in the upper plate side toe portion of the fillet welded portion, and the bead shape is poor. Met.

  No. In No. 16, the distance between the wire target position on the upper plate side of the trailing electrode and the root portion is less than 3 mm and is short, so that an overlap occurs at the bottom plate toe of the fillet welded portion and the bead shape is poor. It was. Further, the upper plate leg length of the fillet welded portion was small, and the leg length was uneven.

  No. In No. 17, since the torch angle with respect to the lower plate of the leading electrode and the trailing electrode was less than 40 °, the arc state was unstable and the amount of spatter was large. In addition, undercuts occurred at the bottom plate side toe portion of the fillet welded portion, the bead shape was poor, the lower plate leg length was small, and the leg length was uneven.

  No. In No. 18, since the wire diameters of the leading electrode and the trailing electrode were less than 1.2 mm and were thin, the arc state was unstable, the amount of spatter was large, and the bead shape was also poor.

  No. In No. 19, since the torch angle with respect to the lower plate of the leading electrode and the trailing electrode was higher than 60 ° and high, the arc state was unstable and the amount of spatter was large. In addition, an overlap occurred at the lower plate side toe portion of the fillet welded portion, and an undercut occurred at the upper plate side toe portion, resulting in a poor bead shape, a small upper plate leg length, and an uneven leg length.

  No. No. 20, since the wire diameter of the leading electrode and the trailing electrode is over 2.0 mm and thick, the wire cannot be fed with a normal wire feeding device, and a dedicated wire feeding device must be installed. The equipment cost was high. Moreover, since the sum total of the slag formation agent of the flux-cored wire for welding (symbol F5) used for the succeeding electrode was less than 3.5%, the slag encapsulating property, the slag peeling property, and the bead shape were poor.

DESCRIPTION OF SYMBOLS 1 Lower plate 2 Upper plate 3 Route part 4 Melting pool of preceding electrode 5 Molten pool of trailing electrode 6 Poor penetration 7 Slag entrainment 8 Undercut 9 Overlap 10 Leading electrode bead 11 Subsequent electrode bead 20, 30 Wire L Leading electrode T trailing electrode D distance between poles S1 lower plate leg length S2 upper plate leg length θ ₁ torch angle θ ₂ advance angle θ ₃ receding angle

Claims (2)

In the two-electrode horizontal fillet gas shielded arc welding method,
Using a solid wire for welding as the leading electrode and a flux-cored wire for welding as the trailing electrode,
The distance between the leading electrode and the trailing electrode is 50 mm or more,
A torch angle with respect to the lower plate of the leading electrode and the trailing electrode is 40 to 60 °,
The wire aiming position of the leading electrode is 5 to 10 mm from the root part to the lower plate side,
3-7mm from the root part to the upper plate side of the wire aiming position of the trailing electrode,
A two-electrode horizontal fillet gas shielded arc welding method characterized by welding a wire diameter of a leading electrode and a trailing electrode at 1.2 to 2.0 mm. The welding flux-cored wire is the mass% with respect to the total mass of the wire.
Contains 3.5 to 8.5% of the total slag forming agent,
The two-electrode horizontal fillet gas shielded arc welding method according to claim 1, wherein the balance is iron powder, alloy powder and inevitable impurities.