KR102117815B1 - Multi-electrode gas-shielded arc one-side welding method - Google Patents

Abstract

Provided is a multi-electrode gas shielded arc single-sided welding method that has a very good back bead formation and excellent impact performance. It includes a leading pole and a trailing pole, the leading pole is reverse polarity, and uses a flux-cored wire or a solid wire, and the leading pole is a wire protruding length (EL): 15-35 mm, welding current (IL): 350~550A and wire feeding amount (WL): 5.0~14.0m/min, the preceding pole satisfies the relationship of 130 ≤ (IL×WL/EL) ≤ 450, and the trailing pole is positive polarity, flux A cored wire is used, and the flux cored wire of the trailing electrode includes metal Al: 1.5-3.5 mass% and Mg: 0.2-1.0 mass%, 2.0 mass% ≤ (metal Al+Mg) ≤ 4.0 mass% , And, 2.0 ≤ (metal Al/Mg) ≤ 10.0, a multi-electrode gas shield arc single-side welding method.

Description

Multi-electrode gas shield arc single-side welding method {MULTI-ELECTRODE GAS-SHIELDED ARC ONE-SIDE WELDING METHOD}

This embodiment relates to a multi-electrode gas shield arc single-side welding method.

The single-sided welding is a welding method in which a refractory backing material is pressed against the improved back side of the butt joint, which is a welded material, and welding is performed from the improved surface side to produce a back bead on the improved back side. Thereby, full penetration can be obtained by welding from only one side side without inverting the butt joint.

The single-side welding can improve its efficiency by performing high currentization of the welding current and reduction (improvement) of the improved cross-sectional area. On the other hand, high-temperature cracking tends to occur in the beads due to high current and narrowing. Therefore, multi-electrode gas shield arc single-sided welding using a multi-electrode including a first electrode and a second electrode, rather than a single electrode, has been proposed.

In the multi-electrode gas shielded arc single-sided welding, it is intended to eliminate the high-temperature crack by remelting the high-temperature crack generated in the weld metal by the first electrode with the second electrode.

For example, in Patent Document 1, specific electrodes are used for the first electrode and the second electrode, and the polarity of the first electrode is reverse polarity, the polarity of the second electrode is positive polarity, and the welding speed, welding current, The values of the distance between the electrodes and the length of the molten paper of the first electrode are defined within a specific range. By doing so, it is intended to obtain a healthy initial layer bead free from high-temperature cracking and to perform single-sided welding with excellent high-temperature cracking resistance with high welding efficiency.

Japanese Patent No. 4319713

However, in the multi-electrode gas shielded arc single-sided welding, the range in which a good back bead is formed is narrow, and the impact performance is low.

Therefore, it is an object of the present invention to provide a multi-electrode gas shielded arc single-sided welding method in which the back bead is formed very well and also has excellent impact performance.

As a result of repeated studies of the present inventors, the impact performance is improved by limiting the components of the flux cored wire of the trailing pole to a specific one, or by employing a non-consumable electrode, while setting the leading electrode to a predetermined condition, Further, by limiting the welding conditions by the preceding electrode and the following electrode to a specific one, it was found that the state of formation of the back surface bead was improved, and the present invention has been completed.

That is, one aspect of the multi-electrode gas shielded arc single-sided welding method according to the present invention is a multi-electrode gas shielded arc single-sided welding method using a plurality of electrodes arranged in a line in the welding line direction, wherein the plurality of electrodes comprises: It includes a trailing pole following the leading pole, the polarity of the leading pole is reverse polarity, and the preceding pole uses a flux cored wire or a solid wire, and the leading pole has a wire protruding length (EL): 15 to 35 ㎜, welding current (IL): 350 to 550 A and wire feeding amount (WL): 5.0 to 14.0 m/min, the EL (mm), the IL (A) and the WL (m/min) of the preceding electrode Satisfies the relationship of 130 ≤ (IL×WL/EL) ≤ 450, the polarity of the trailing pole is positive, and the flux cored wire is used in the trailing pole, and the flux cored wire of the trailing pole is also used. Is a metal Al: 1.5 to 3.5% by mass and Mg: 0.2 to 1.0% by mass, and the content of the metal Al and the Mg is 2.0 mass% ≤ (metal Al+Mg) ≤ 4.0 mass%, and 2.0 ≤ (metal Al/ Mg) is characterized by satisfying the relationship of ≤ 10.0.

Here, the content of Mg is a value obtained by converting metal Mg and oxide Mg into Mg.

One aspect of the multi-electrode gas shielded arc single-side welding method according to the present invention, the trailing pole has a wire protruding length (ET): 15 to 35 mm, a welding current (IT): 160 to 400 A, and a wire feeding amount (WT): It is characterized by being 1.0 to 10.0 m/min.

In one aspect of the multi-electrode gas shielded arc single-side welding method according to the present invention, the ET (mm), the IT (A) and the WT (m/min) of the trailing pole are 5 ≤ (IT×WT/ET). It is characterized by satisfying a relationship of ≤ 150.

One aspect of the multi-electrode gas shielded arc single-side welding method according to the present invention is characterized in that the welding speed: 200 to 400 mm/min and the distance between the leading and trailing poles is 20 to 50 mm.

One aspect of the multi-electrode gas shield arc single-side welding method according to the present invention is characterized in that the weaving width of the preceding electrode: 0-5 mm and the weaving width of the trailing electrode: 0-5 mm.

One aspect of the multi-electrode gas shielded arc single-sided welding method according to the present invention is a multi-electrode gas shielded arc single-sided welding method using a plurality of electrodes arranged in a line in the direction of the welding line, wherein the plurality of electrodes is a preceding electrode, and the preceding It includes a trailing pole leading to the pole, the polarity of the preceding pole is reverse polarity, and the preceding pole uses a flux cored wire or a solid wire, and the preceding pole has a wire protruding length (EL): 15 to 35 mm, Welding current (IL): 350 to 550 A and wire feeding amount (WL): 5.0 to 14.0 m/min, and the EL (mm), the IL (A), and the WL (m/min) of the preceding electrode are 130 ≤ (IL×WL/EL) ≤ 450, the polarity of the trailing electrode is positive, and the non-consumable electrode is used in the trailing pole.

One aspect of the multi-electrode gas shielded arc single-sided welding method according to the present invention, when using a non-consumable electrode as the trailing pole, welding speed: 200 to 400 mm/min, the distance between the leading and trailing poles : 20-50 mm and the welding current (IT) of the trailing pole: 160-300 A.

One aspect of the multi-electrode gas shielded arc single-side welding method according to the present invention is characterized in that the material to be welded is a V-type butt with a plate thickness: 12-50 mm and an improvement angle: 30-60°.

According to the present invention, in the multi-electrode gas shielded arc single-side welding, a very good back-bead formation state can be obtained, and a welding material excellent in good impact performance can also be obtained.

1 is a schematic diagram for showing the structure of a V-type butt that is an example of a material to be welded used for single electrode welding of a multi-electrode gas shield.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail. In addition, this invention is not limited to embodiment demonstrated below. In addition, in this specification, "-" which represents a numerical range is used by the meaning containing the numerical value described before and after that as a lower limit and an upper limit.

The multi-electrode gas shielded arc single-sided welding method according to the present embodiment (hereinafter sometimes referred to simply as a "welding method") uses a plurality of electrodes arranged in a line in the direction of the welding line, and the plurality of electrodes are preceded electrodes. And, includes a trailing pole following the leading pole, the polarity of the leading pole is reverse polarity, and the leading pole uses a flux cored wire or a solid wire, and the leading pole has a wire protruding length (EL): 15 -35 mm, welding current (IL): 350 to 550 A and wire feeding amount (WL): 5.0 to 14.0 m/min, the EL (mm), the IL (A) and the WL (m/) of the preceding electrode Min) satisfies the relationship of 130 ≤ (IL×WL/EL) ≤ 450, the polarity of the trailing pole is positive, and the flux cored wire is used in the trailing pole, and also the flux core of the trailing pole The de wire contains metal Al: 1.5-3.5 mass% and Mg: 0.2-1.0 mass%, and the content of the metal Al and the Mg is 2.0 mass% ≤ (metal Al+Mg) ≤ 4.0 mass%, and 2.0 ≤ (metal Al/Mg) ≤ 10.0.

Here, the content of Mg is a value obtained by converting metal Mg and oxide Mg into Mg.

In addition, the multi-electrode gas shielded arc single-sided welding method according to the present embodiment is a multi-electrode gas shielded arc single-sided welding method using a plurality of electrodes arranged in a line in the welding line direction, wherein the plurality of electrodes is a preceding electrode and the preceding It includes a trailing pole leading to the pole, the polarity of the preceding pole is reverse polarity, and the preceding pole uses a flux cored wire or a solid wire, and the preceding pole has a wire protruding length (EL): 15 to 35 mm, Welding current (IL): 350 to 550 A and wire feeding amount (WL): 5.0 to 14.0 m/min, and the EL (mm), the IL (A), and the WL (m/min) of the preceding electrode are 130 ≤ (IL×WL/EL) ≤ 450, the polarity of the trailing pole is positive, and a non-consumable electrode is used in the trailing pole.

<Previous play>

The polarity of the preceding electrode in this embodiment is a consumable electrode of reverse polarity (DCEP), and a flux-cored wire or a solid wire (hereinafter sometimes referred to simply as "wire") is used. The leading electrode satisfies the wire protruding length (EL): 15 to 35 mm, welding current (IL): 350 to 550 A, and wire feeding amount (WL): 5.0 to 14.0 m/min, (IL×WL/EL) By setting the value represented by 130 or more and 450 or less, the bead formation state can be improved.

That is, when the wire protruding length EL is 15 mm or more, the stability of the back bead is improved, and dissolution can also be prevented. The protruding length of the wire is preferably 17 mm or more, and more preferably 19 mm or more. In addition, when the wire protruding length is 35 mm or less, the back bead is easily formed. The wire protruding length is preferably 33 mm or less, and more preferably 31 mm or less.

By setting the welding current IL to 350 A or more, it is easy to form the back bead. The welding current is preferably 370 A or more, and more preferably 400 A or more. In addition, when the welding current is set to 550 A or less, the stability of the bead becomes good and dissolution can be prevented. The welding current is preferably 530 A or less, and more preferably 500 A or less.

When the wire feeding amount WL is 5.0 m/min or more, the formation of a bead becomes easy. The wire feeding amount is preferably 5.5 m/min or more, and more preferably 6.0 m/min or more. In addition, when the wire feeding amount is 14.0 m/min or less, the stability of the bead becomes good, and dissolution can also be prevented. The wire feeding amount is preferably 13.0 m/min or less, and more preferably 12.0 m/min or less.

The wire protruding length (EL) (mm), welding current (IL) (A), and wire feeding amount (WL) (m/min) are (IL×WL/EL) (unit: A·m/min·mm) By setting the indicated value to 130 or more, it becomes possible to protrude the back bead on the back side of the material to be welded during welding. The value represented by (IL×WL/EL) is preferably 200 or more, more preferably 250 or more, and particularly preferably 280 or more. Further, by setting the value indicated by (IL×WL/EL) to 450 or less, it is possible to prevent excessive protrusion of the bead. The value represented by (IL×WL/EL) is preferably 400 or less, more preferably 350 or less, and particularly preferably 320 or less.

The welding voltage VL of the preceding electrode is not particularly limited, but 35 V or more is preferable from the viewpoint of arc stability, and 38 V or more is more preferable. Further, the welding voltage is preferably 45 V or less in terms of arc stability, and more preferably 43 V or less.

The weaving width of the preceding electrode is not particularly limited, but it is preferable to set it to 0 to 5 mm since the bead formation state is improved, more preferably 2 mm or more, and more preferably 4 mm or less.

It is preferable to use an iron-based flux cored wire or a solid wire for the flux cored wire of the preceding electrode. The flux-cored wire is a wire filled with flux in a steel sheath, but the composition of the wire varies depending on the type of the material to be welded and the welding conditions, and is not particularly limited.

As the flux cored wire of the preceding electrode, it is possible to use, for example, an Fe content of 80 to 95% by mass relative to the entire wire. Examples of elements that can be contained in the wire other than Fe include C, Mn, Ti, P, S, Ni, Si, Cr, Cu, Mo, Mg, B, F, Na, K, Nb, V, Zr, Al, etc. Can be heard. These may be included as active additions and as inevitable impurities.

The solid wire is not limited, but examples include C: 0.01 to 0.18 mass%, Si: 0 to 1.00 mass%, Mn: 0.50 to 2.80 mass%, P: 0.030 mass% or less, and S: 0.030 mass%. Below, and Cu: 0.50 mass% or less is contained, the balance is Fe and inevitable impurities. Others may include Ti, Ni, Cr, Al, Zr, Mg, and the like.

Although the wire diameter of the flux cored wire or solid wire of the preceding electrode is not particularly limited, 1.0 mm or more is preferable from the viewpoint of welding workability. Moreover, 2.0 mm or less is preferable from the point of welding workability.

The shielding gas used for welding by the preceding electrode is not particularly limited, but, for example, Ar gas, carbon dioxide gas, a mixed gas of Ar gas and carbon dioxide gas, or a mixed gas of Ar gas and oxygen gas can be used. The flow rate of the gas is also not particularly limited, but can be, for example, 15 to 30 L/min.

<Trailing pole: Flux cored wire>

The trailing electrode in the present embodiment is an electrode following the preceding electrode, and the polarity is a positive electrode (DCEN) consumable electrode. The flux cored wire used for the trailing electrode contains 1.5 to 3.5% by mass of metal Al, 0.2 to 1.0% by mass of Mg, and a value represented by (metal Al/Mg) of 2.0 to 10.0. Here, Mg is a value obtained by converting metal Mg and oxide Mg into Mg, and is also referred to as “Mg component” hereinafter.

The metal Al contained in the flux-cored wire has a content of 1.5% by mass or more with respect to the total mass of the wire, and the impact performance is improved by the deoxidation effect. The content of the metal Al is preferably 1.8% by mass or more, and more preferably 2.0% by mass or more. Moreover, content of metal Al is 3.5 mass% or less, and it does not become an excessive deoxidizing element, and impact performance improves. The content of the metal Al is preferably 3.2% by mass or less, and more preferably 3.0% by mass or less.

When the Mg component contained in the wire has a content of 0.2% by mass or more with respect to the total wire mass, the impact performance is improved by the deoxidation effect. The content of the Mg component is preferably 0.3% by mass or more, and more preferably 0.4% by mass or more. In addition, the content of the Mg component is 1.0% by mass or less, so that the deoxidizing element does not become excessive, and deterioration in impact performance due to excessive strength can be prevented. The content of the Mg component is preferably 0.9% by mass or less, and more preferably 0.8% by mass or less.

When the ratio of the metal Al and Mg components (metal Al/Mg) contained in the wire is 2.0 or more, the deoxidizing effect by Mg can be effectively exhibited, and impact performance is improved. (Metal Al/Mg) is preferably 3.0 or more, more preferably 4.0 or more, and particularly preferably 5.0 or more.

Moreover, since (metal Al/Mg) is 10.0 or less, it does not become an excessive deoxidizing element, and it is possible to prevent deterioration of impact performance due to excessive strength. (Metal Al/Mg) is preferably 9.0 or less, more preferably 8.0 or less, and particularly preferably 7.0 or less.

Although the composition of the wires other than the metal Al and Mg components differs depending on the type of the material to be welded and the welding conditions, for example, at least one element selected from the following elements may be included in the following range.

C: 0.01 to 0.1 mass%, Zr: 0.01 to 0.15 mass%, Mn: 0.5 to 2.5 mass%, and Si: 0.1 to 1.0 mass%

[C: 0.01 to 0.1 mass%]

C has the effect of improving the strength and toughness of the weld metal, and also affects the spatter generated during welding. As for the spatter, there is no particular lower limit since the content of C is small even if it is small, but it is practical that it is 0.01 mass% or more. Moreover, 0.03 mass% or more is preferable at the point which ensures the strength and toughness of a weld metal.

On the other hand, when the amount of C increases, the volume shift is not stable, and the amount of spatters increases. Therefore, the content of C is preferably 0.1% by mass or less, and more preferably 0.08% by mass or less.

[Zr: 0.01 to 0.15 mass%]

Zr is an element that exerts an effect of improving arc stability. When it contains Zr, 0.01 mass% or more is preferable, and 0.05 mass% or more is more preferable.

On the other hand, when Zr is contained in a large amount, the scale layer after the annealing process may become thick and the adhesion of the scale may also increase. Therefore, the content is preferably 0.15 mass% or less, and more preferably 0.10 mass% or less.

[Mn: 0.5 to 2.5 mass%]

Mn is an effective element for exerting an effect as a deoxidizing material and securing the strength and toughness of the weld metal, and preferably contains 0.5% by mass or more, and more preferably 1.0% by mass or more.

On the other hand, when Mn is contained in a large amount, since slag may be generated in large quantities during welding, or the strength may be too high to significantly degrade the toughness of the weld metal, the content is preferably 2.5% by mass or less, and 2.0% by mass or less It is more preferable.

[Si: 0.1 to 1.0 mass%]

Si is a deoxidizing element, has an effect of securing the strength and toughness of the weld metal, preferably contains 0.1% by mass or more, and more preferably 0.3% by mass or more.

On the other hand, if Si is contained in a large amount, there is a possibility that a large amount of slag is generated during welding, or the strength is too high to deteriorate the toughness of the weld metal, so its content is preferably 1.0 mass% or less, more preferably 0.8 mass% or less. Do.

The main component of the remainder of the wire is Fe, but the remainder of the wire can contain what can be contained in the wire commonly 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.

The metal additive is composed of a simple substance or an alloy of metal, and specific examples thereof include Ni, Cr, Cu, Mo, Ti, Ca, Li, Nb, and B. The F compound is an element that reduces the amount of diffusible hydrogen in the weld metal, and includes CaF, BaF ₂ , NaF, K ₂ SiF ₆ , SrF ₂ , AlF ₃ , MgF ₂ , and LiF. Examples of the arc stabilizer include Na and K compounds. Examples of the slag forming agent include Al ₂ O ₃ , MgO, and TiO ₂ . P or S is often included as an unavoidable impurity, but may be actively added depending on the purpose.

For example, Fe (total of Fe oxide and Fe): 85~95%, Ni ≤ 2.0%, Cr ≤ 0.2%, Mo ≤ 0.5%, F compound ≤ 0.3%, (Na+K) ≤ 0.2%, Nb ≤ 0.1 %, V ≤ 0.1%, Al ₂ O ₃ ≤ 0.5%, Ti ≤ 0.5%, TiO ₂ ≤ 8.0%, MgO ≤ 5.0%, B ≤ 0.02%, P ≤ 0.03%, S ≤ 0.03%.

The remainder contains inevitable impurities. Examples of the inevitable impurities include O, N, Sb, and As. In addition, O and N are also actively added.

In the flux-cored wire of the trailing pole, the flux is filled inside the forced outer sheath having a cylindrical shape, but a seamless wire (seamless type) welded to the butt of the forced outer sheath and a gap without welding the butt Any structure of the wire (seam type) left as it is can be employed. Further, copper plating may be applied to the outer side of the outer shell.

Although the wire diameter of the flux cored wire of the trailing pole is not particularly limited, 1.0 mm or more is preferable from the viewpoint of welding workability. Moreover, 2.0 mm or less is preferable from the point of welding workability.

For the trailing pole, it is ghost line after welding that satisfies the wire protruding length (ET): 15 to 35 mm, welding current (IT): 160 to 400 A, and wire feeding amount (WT): 1.0 to 10.0 m/min. ) Is preferable in that it can be completely lost. Moreover, it is also preferable to set the value represented by (IT x WT/ET) to 5 or more and 150 or less in that the ghost line can be completely lost.

That is, by setting the wire protruding length ET to 15 mm or more, the arc force is sufficient, and the ghost line can be completely lost, which is preferable. The wire protruding length is more preferably 17 mm or more, and even more preferably 19 mm or more. In addition, by making the wire protruding length 35 mm or less, the arc force becomes sufficient and the ghost line can be completely lost. In addition, the arc is stable and the amount of spatters is also reduced, which is preferable. The wire protruding length is more preferably 33 mm or less, and even more preferably 31 mm or less.

The arc current is sufficient by setting the welding current IT to 160 A or more, which is preferable because the ghost line can be completely lost. The welding current is more preferably 180 A or more, and even more preferably 200 A or more. In addition, by setting the welding current to 400 A or less, the arc force is sufficient, and in addition to the fact that the ghost line can be completely lost, the arc is stable and the amount of spatters is also reduced, which is preferable. The welding current is more preferably 380 A or less, and even more preferably 350 A or less.

It is preferable to make the wire feeding amount WT 1.0 m/min or more, because the arc force becomes sufficient and the ghost line can be completely lost. The wire feeding amount is more preferably 1.2 m/min or more, and even more preferably 1.4 m/min or more. In addition, by setting the wire feeding amount to 10.0 m/min or less, the arc force is sufficient, and in addition to the fact that the ghost line can be completely lost, the arc is stable and the amount of spatters is also reduced, which is preferable. The wire feeding amount is more preferably 9.8 m/min or less, and even more preferably 9.6 m/min or less.

Wire protruding length (ET) (mm), welding current (IT) (A), and wire feeding amount (WT) (m/min) are (IT×WT/ET) (unit: A·m/min·mm) It is preferable because the ghost line can be completely lost by setting the indicated value to 5 or more. The value represented by (IT×WT/ET) is more preferably 25 or more, further preferably 45 or more, and particularly preferably 55 or more. Moreover, it is preferable because the value represented by (IT x WT/ET) is set to 150 or less, since it is possible to prevent the generation of ghost lines due to the trailing pole. The value represented by (IT×WT/ET) is more preferably 130 or less, even more preferably 110 or less, and particularly preferably 100 or less.

Although the welding voltage VT of the trailing pole is not particularly limited, 15 V or more is preferable from the viewpoint of arc stability, and 20 V or more is more preferable. Further, the welding voltage is preferably 40 V or less from the viewpoint of arc stability, and more preferably 35 V or less.

Although the weaving width of the trailing electrode is not particularly limited, it is preferable that the beading of 0 to 5 mm improves the bead formation state, more preferably 2 mm or more, and more preferably 4 mm or less.

The shielding gas used for welding by the trailing electrode is not particularly limited, but, for example, Ar gas, carbon dioxide gas, a mixed gas of Ar gas and carbon dioxide gas, or a mixed gas of Ar gas and oxygen gas can be used. The flow rate of the gas is also not particularly limited, but can be, for example, 15 to 30 L/min.

<Trailing pole: Non-consumable electrode>

The trailing electrode in the present embodiment is an electrode that follows the preceding electrode, and the polarity is a non-consumable electrode of positive polarity (DCEN). In the trailing electrode, a tungsten electrode is used as the non-consumable electrode, and TIG arc welding or plasma arc welding is performed. Moreover, in TIG arc welding, it is preferable that a filler rod is not used.

In TIG arc welding or plasma arc welding, with the heat input from the trailing electrode (tungsten electrode), the temperature near the surface of the molten metal becomes higher than the temperature inside the molten metal, and the final solidification part becomes a position near the bead surface (solidification mode) change). By changing the direction of the final solidification, the growth of the solidification does not become one direction, and the impact performance can be improved. The amount of welding in which a solidification form change occurs can be set to a particularly appropriate amount in the case where the wire feeding amount WL of the preceding electrode is 5.0 to 14.0 m/min, and very excellent impact performance can be obtained.

As the electrode material of the tungsten electrode, pure tungsten, thorium oxide tungsten, lanthanum oxide tungsten and cerium oxide tungsten, yttrium oxide tungsten and zirconium oxide tungsten, etc., as specified in JIS Z 3233 (2001), are used. Can be.

The welding torch may be provided with a gas nozzle, like the welding torch generally used in TIG arc welding. A non-consumable electrode is disposed inside the gas nozzle. An inert gas such as argon gas or helium gas is supplied into the gas nozzle, and during TIG welding, the inert gas is ejected as a shield gas from an opening of the gas nozzle. In addition, in the plasma arc welding, plasma-like inert gas is also ejected from the opening of the gas nozzle.

The trailing pole is preferable in that it satisfies the welding current (IT): 160 to 300 A, in order to secure excellent impact performance and completely lose the ghost line after welding.

The welding voltage VT of the trailing pole is not particularly limited, but 10 V or more is preferable from the viewpoint of arc stability. Further, the welding voltage is preferably 20 V or less from the viewpoint of arc stability.

As the shielding gas used for welding by the trailing electrode, Ar gas, He gas, or the like is used for TIG arc welding, and plasmad Ar gas, He gas, or the like is used for plasma arc welding. The flow rate of the gas is not particularly limited, but can be, for example, 10 to 15 L/min.

<welding conditions>

The distance between the leading and trailing poles is preferably 20-50 mm. By setting the distance between the poles to 20 mm or more, it is possible to prevent weld metals from being formed at each of the leading and trailing poles, and the welding metals are united. As a result, good high temperature crack resistance can be obtained, which is preferable. The distance between the poles is more preferably 25 mm or more, and even more preferably 30 mm or more.

By setting the distance between the poles to 50 mm or less, the molten paper can be reheated to the trailing electrode before the molten paper by the preceding electrode solidifies, thereby preventing the molten paper from becoming a complete two pool. As a result, good high temperature crack resistance can be obtained, which is preferable. The distance between the poles is more preferably 45 mm or less, and even more preferably 40 mm or less.

The welding speed is preferably 200 to 400 mm/min. By setting the welding speed to 200 mm/min or more, the weld metal does not lead, and good back beads can be obtained. The welding speed is more preferably 230 mm/min or more, and even more preferably 250 mm/min or more.

By setting the welding speed to 400 mm/min or less, the cooling rate of the weld metal is not too fast, and ghost lines can be prevented from being generated, which is preferable. The welding speed is more preferably 380 mm/min or less, and even more preferably 350 mm/min or less.

The welding method according to the present embodiment can be used for various shapes, such as V-shaped, U-shaped, I-shaped, X-shaped, or H-shaped. 1 is a simplified schematic diagram in the case where the disclosed steel sheet 1 is a V-shaped butt. As for the V-shaped butt of the steel sheet 1, for example, if the plate thickness t is 12-50 mm, and the (V-type) improvement angle θ of the V-type improvement 10 is 30-60°, the beads are It is preferable, because the formation state of is improved. The root gap 3 of the V-shaped improvement 10 is preferably 0 to 5 mm.

In the welded article obtained by the welding method according to the present embodiment, the absorbed energy obtained by the Charpy impact test at 0°C according to JIS Z 3313:2009 is preferably 47 J or more, more preferably 60 J or more, and 80 J or more. The above is more preferable, and 100 J or more is particularly preferable.

The state of forming the back bead is preferably formed without welding defects such as undercuts or overlaps over the entire length, and it is more preferable that the standard deviation of the added height of the back bead full length is 0.5 or less, and less than 0.4 Is more preferable, and 0.3 or less is particularly preferred.

The high-temperature cracking resistance can be evaluated based on the "C-type jig restraint butt welding crack test method" specified in JIS Z 3155:1993. When the JIS G 3106 SM490A is used as the base material, the crack rate is preferably 10% or less, more preferably 8% or less, more preferably 6% or less, even more preferably 4% or less, and particularly 0%. desirable.

As arc stability at the time of welding, the less the shaking of the arc and the less arc breaks, the more preferable.

[Example]

The present embodiment will be described in more detail with reference to Examples below, but the present invention is not limited to these Examples, and it is possible to implement it by changing it in a range suitable for the spirit of the present invention. It is included in the technical scope of the present invention.

<Examples 1 to 40 and Comparative Examples 1 to 18>

Multi-electrode gas shielded arc single-sided welding was performed under the conditions described in Table 1 or Table 2. In the table, "DCEP" or "DCEN" indicates that the polarity of the electrode is reverse polarity or positive polarity, respectively. The welding voltages of the leading and trailing poles were taken as the values shown in Table 1. As for the wire diameter, the leading electrode was 1.6 mm and the trailing electrode was 1.4 mm. For the shielding gas, the flow rate was 25 L/min using carbon dioxide gas for welding by the preceding electrode, and the flow rate was 25 L/min using carbon dioxide gas for welding by the trailing electrode.

As the flux-cored wire in the preceding electrode, a metal-based flux-cored wire according to JIS Z 3313:2009 was used. As the solid wire in the preceding electrode, for example, a solid wire according to JIS Z 3312:2009, containing Fe: 90 mass%, Mn: 2.5 mass%, and Si: 0.5 mass% was used. As the trailing electrode, a basic flux cored wire having the composition shown in Table 3 was used. The remainder of Table 3 are Fe, F compounds and inevitable impurities. In addition, a V-shaped butt was used for the material to be welded. The plate thickness and the angle of improvement of the V-shaped butt are as described in Table 1 or Table 2.

In Table 1 and Table 2, EL is the wire protruding length of the preceding electrode (mm), IL is the welding current (A) of the preceding electrode, WL is the wire feeding amount (m/min) of the preceding electrode, and ET is the trailing electrode. The wire protruding length of (㎜), IT means the welding current (A) of the trailing pole, and WT means the wire feeding amount (m/min) of the trailing pole, respectively. The unit of welding voltage is V, and the unit of welding speed is mm /Min, the distance between poles indicates the distance between the leading and trailing poles, the unit is mm, the unit of plate thickness is mm, and the unit of improvement angle is ° (degree).

<Examples 41 to 45>

Multi-electrode gas shielded arc single-sided welding was performed under the conditions described in Table 5. In the table, "DCEP" or "DCEN" indicates that the polarity of the electrode is reverse polarity or positive polarity, respectively. The welding voltages of the leading and trailing poles were taken as values shown in Table 5. The wire diameter of the preceding electrode was 1.6 mm, and the flow rate of the shield gas was 25 L/min using carbon dioxide gas. Ar gas was used for welding by the trailing electrode, the flow rate was 15 L/min for TIG arc welding, and the flow rate was 10 L/min for plasma gas arc welding.

As the flux-cored wire in the preceding electrode, a metal-based flux-cored wire according to JIS Z 3313:2009 was used. As the solid wire in the preceding electrode, for example, a solid wire according to JIS Z 3312:2009 containing Fe: 90 mass%, Mn: 2.5 mass%, and Si: 0.5 mass% was used. A tungsten electrode having a diameter of 4.0 mm was used as the trailing electrode.

V-butting was used for the material to be welded. The plate thickness and the angle of improvement of the V-type butt are as described in Table 5.

In Table 5, EL is the wire protruding length of the preceding electrode (mm), IL is the welding current (A) of the preceding electrode, WL is the wire feeding amount (m/min) of the preceding electrode, and IT is the welding current of the following electrode. Means (A), the unit of welding voltage is V, the unit of welding speed is mm/min, and the distance between poles is the distance between the leading and trailing poles, the unit is mm, the unit of plate thickness is mm, and the improvement angle The unit of is ° (degree).

<Evaluation>

The welding performance at the time of welding and after welding was evaluated for impact performance, back bead formation, high temperature crack resistance, and arc stability. The details of each evaluation are as follows, and the results are shown in Tables 4 and 6.

(Shock performance: Charpy impact test at 0℃)

About the welded object, the impact performance was evaluated by finding the absorbed energy (J) at 0°C by a Charpy impact test according to JIS Z 3313:2009.

The absorption energy by each test at 0°C is preferably 47 J or more, 60 J or more is better, 80 J or more is better, and 100 J or more is particularly good.

(Back bead formation state)

For the weldment, the state of formation of the backside beads was evaluated by visual and standard deviation of the height of the backside beads. The standard deviation of the height of the back bead was measured using a laser displacement meter.

"◎+" in Tables 4 and 6 means that there are no welding defects such as undercuts and overlaps as a result of the naked eye, and that the standard deviation of the height of the back bead is 0.3 or less. Means more than 0.3 and less than 0.4, "○+" means no welding defect, standard deviation is more than 0.4 and less than 0.5, "○" is formed without welding defect over the entire length, and standard deviation exceeds 0.5 It means that, and "x" means that a bead is not formed.

<Cracking resistance at high temperature>

The high-temperature cracking resistance of the weld metal was evaluated based on the "C-type jig restraint butt weld crack test method" specified in JIS Z 3155:1993. In addition, the base material used is JIS G 3106 SM490A.

"◎+" in Table 4 and Table 6 means that the crack rate is 0%, "◎" means that the crack rate is more than 0% and 4% or less, and "○+" means that the crack rate is more than 4% 8 % Or less, "○" means that the crack rate is more than 8% and 10% or less, and "△" means that the crack rate is more than 10% and 20% or less.

<arc stability>

The arc stability at the time of welding was comprehensively sensory evaluated for arc shaking and arc breaking during welding.

"○" in Table 4 and Table 6 means that there was no arc shake or arc break, and that it was satisfactory, and "X" means that arc shake was large or arc break was seen.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

From the results of Tables 4 and 6, in the welding method according to the present embodiment, the flux-cored wire, or non-consumable type, in which the metal Al and Mg components in the trailing electrode are within a predetermined range while the preceding electrode is set to a predetermined condition. It was found that the impact performance was improved by using the electrode.

In addition, it was found that the state of forming the back bead is very good by setting conditions such as the polarity of the preceding electrode and the length of the wire protruding within a predetermined range.

In addition to this, it was found that when using a flux cored wire as a trailing pole, excellent high-temperature cracking resistance can be achieved by setting conditions such as wire protruding length within a predetermined range.

1: Disclosure steel sheet 2: Backing material
3: Root gap 10: V-shaped improvement

Claims (8)

delete delete delete delete delete In the single electrode welding method of a multi-electrode gas shield arc using a plurality of electrodes arranged in a line in the direction of the welding line,
The plurality of electrodes includes a preceding electrode and a trailing electrode following the preceding electrode,
The polarity of the preceding electrode is reverse polarity,
In the preceding electrode, flux-cored wire or solid wire is used,
The preceding electrode has a wire protruding length (EL): 15 to 35 mm, a welding current (IL): 350 to 550 A, and a wire feeding amount (WL): 5.0 to 14.0 m/min.
The EL (mm), the IL (A), and the WL (m/min) of the preceding electrode satisfy a relationship of 130 ≤ (IL×WL/EL) ≤ 450,
The polarity of the trailing pole is positive.
In addition, the trailing pole uses a non-consumable electrode without the use of a filler rod,
Welding speed: 200~400㎜/min
Multi-electrode gas shield arc single side welding method. The method of claim 6,
The distance between the leading and trailing poles is 20-50 mm and the welding current (IT) of the trailing poles is 160 to 300 A.
Multi-electrode gas shield arc single side welding method. The method of claim 6,
The material to be welded is plate-shaped: 12~50㎜ and improvement angle: 30~60° V-butting
Multi-electrode gas shield arc single side welding method.

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