WO2011031022A2

WO2011031022A2 - Welding wire

Info

Publication number: WO2011031022A2
Application number: PCT/KR2010/005716
Authority: WO
Inventors: 김재성; 이보영; 최동순
Original assignee: 한국항공대학교 산학협력단
Priority date: 2009-09-11
Filing date: 2010-08-25
Publication date: 2011-03-17
Also published as: KR20110027905A; KR101205332B1; WO2011031022A3; JP2013504434A

Abstract

The present invention relates to a welding wire used in arc welding such as gas metal arc welding and flux cored arc welding using a protective gas and submerged arc welding using a flux, and provides a welding wire comprising: a core layer which is melted and turns into droplets due to the heat of the arc during welding; and an ionization potential layer which is formed on the surface of the core layer and consists of an element having low ionization energy, the welding wire being devised so as to exhibit a stable arc and metal transfer mode thereby making it possible to reduce the occurrence of short circuiting and spattering and so improve the quality of welding.

Description

Welding wire

The present invention relates to a welding wire, and more particularly, to a low ionization energy element on the surface of a wire when used for gas metal arc welding using a protective gas, fluxcored arc welding, and submerged arc welding using a flux. Due to this, it is possible to have a stable arc and metal transition mode even at a lower current range than the conventional one, and to a welding wire having a higher arc efficiency than a conventional one at a high current.

Welding is a method in which the joints of two or more materials to be joined are melted by heat to rearrange and bond atomic bonds of two different materials. There are various welding methods such as arc welding and gas welding.

Arc welding in this welding method is to join the two metals by the electric arc heat generated between the electrode and the surface of the base material, usually to protect the weld from the atmosphere O ₂ , N _2, etc. using a protective gas and flux, The wire is welded with filler metal. At this time, the wires used for arc welding as described above are mostly used at home and abroad are copper-plated wires or unplated wires by chemical reaction or electrolytic reaction on the surface.

In addition, arc welding generally used in the manufacturing industry includes gas metal arc welding, flux cored arc welding, or submerged arc welding. Among them, arc welding such as gas metal arc welding and fluxcored arc welding can be continuously supplied by using one or more gases such as carbon dioxide (CO ₂ ), argon (Ar), and helium (He) as the protective gas. It is a welding method in which a wire is melted and joined by supplying a solid wire or fluxcore wire and causing an arc to occur at the tip of the wire.

The submerged arc welding uses a molten flux and a sintered flux to supply a solid wire that can be continuously fed, and a slag made by the flux is formed during welding to cause an arc to occur at the tip thereof to melt the wire. It is a welding method to be joined.

In this case, when argon (Ar) gas is used as the protective gas in the transition current range of 250 A or more for gas metal arc welding and flux cored arc welding, the metal transition mode of the volume during arc welding using argon gas as the protective gas will be described. As shown in FIG. 1, which is a conceptual diagram, an arc b is generated at an upper portion of the volume a, and a fine spray type spray transfer is performed in which the volume a is smaller than the diameter of the wire c. This spray type volume transfer is the best transfer type among the volume (a) transition forms, and it is a volume transition that is known to have less spatter, excellent weld bead shape, and is suitable for high speed welding. It is used in the field.

However, argon gas is about five times more expensive than carbon dioxide gas, and thus, in actual field welding, carbon dioxide gas is more often used as a protective gas than argon gas.

Since carbon dioxide gas is a low cost and high efficiency welding method, it is widely used as a protective gas for gas metal arc welding and fluxcore arc welding, such as welding of steel materials. In particular, due to the rapid spread of automatic welding, it is used in various fields such as shipbuilding, construction, bridges, automobiles, construction machinery, etc. Among others, in the field of shipbuilding, construction, bridges, it is used for high current multilayer welding of thick plates, In the field of construction machinery, it is often used for fillet welding of thin plates.

However, when carbon dioxide gas is used as the protective gas as described above, the welding wire has a volume of 2 to 4 times larger than that of argon gas welding over the transition current region or welding using Ar-CO ₂ mixed gas as the protective gas. As shown in FIG. 2, which is a conceptual diagram illustrating a metal transition mode of a volume during arc welding using a carbon dioxide gas as a protective gas, a granular volume transfer in which an arc b is generated under a volume a ( Due to globular transfer, a large amount of spatter is generated during short circuit and re-arc (b) with the base material (ie steel sheet), and the arc (b) is not stabilized, so that the bead shape is not stable. In this case, there is a problem that the bead shape tends to be chopped (so-called humping bead).

In addition, when argon gas is used as the protective gas or Ar-CO ₂ mixed gas is used as the protective gas when welding under the transition current region, argon gas welding above the transition current region is performed as in the case of using the carbon dioxide gas as the protective gas. Compared with Ar-CO ₂ mixed gas welding, 1 ~ 4 times larger volume is attached to the tip of the welding wire, so the volumetric metal transition mode is formed by the granular displacement as shown in FIG. The speed is low and the arc control is not easy.

In order to solve the above problems, a method of reducing the spatter generated by the addition of potassium (K) has been disclosed in Japanese Patent Application Laid-Open No. 6-218574, which uses 100% of CO ₂ gas as a protective gas. In welding, spatter reduction and bead shape stabilization through arc stabilization could not be obtained.

In addition, US Patent 10 / 107,623 has developed a steel wire for MAG welding and a MAG welding method using the same, but this targets low current (less than 25A) welding of a thin steel sheet with a gap in the welding portion, and as a protective gas, Sufficient arc stability could not be obtained in welding in the transition current region or more in gas metal arc welding using ₂ % of gas.

In addition, Patent No. 10-0553380, filed in Japan and registered in Korea, proposes a carbon steel shield arc welding steel wire and a welding method using the same, but in a welding method using a mixed gas of CO ₂ and Ar gas. In the case of welding using low-cost CO ₂ gas at 100%, the economical effect of reducing the welding material cost cannot be obtained.

In addition, Patent No. 10-2008-0006471, filed in Japan and published in Korea, proposes a solid wire, but is limited to a copper plated wire used for thin arc welding, and improves arc stability according to a change in metal transition mode. It could not bring enough effect to reduce spatter, reduce welding cost and improve welding quality.

The present invention is to solve the above problems,

In case of welding, 100% of carbon dioxide (CO ₂ ) gas is used as the protection gas in all current areas, or when argon (Ar) or argon-carbon dioxide (Ar-CO ₂ ) is used as protection gas in the transition current area or less. It is an object to provide a welding wire that can exhibit stable arc and metal volume transitions.

In addition, another object of the present invention is to further increase the welding efficiency.

The present invention to achieve the above object,

A core layer melted by arc heat during welding to make a weld metal;

It provides a welding wire comprising a; ionization potential layer formed on the surface of the core layer, made of an element having a low ionization energy.

In addition, a conductive layer is further provided between the core layer and the ionization potential layer or on the surface of the ionization potential layer to transfer electricity flowing through the wire to the core layer.

In addition, the ionization potential layer is characterized in that it further comprises a metal having conductivity.

In addition, the element of the ionization potential layer is Cs, Rb, K, Lu, Na, Ra, Li, Sm, La, Eu, Sr, In, Al, Ga, Tl, Ca, Gd, whose primary ionization energy is 7eV or less. Select from Yb, S, Y, V, Cr, Nb, Ti, Zr or Pt, Pd, Sc, Sn, Mg, Mn, Ge, Si, Bi, where the sum of primary ionization energy and secondary ionization energy is 25 eV or less It is characterized by consisting of one or more elements.

In addition, the core layer is one metal or two or more alloy metals selected from iron, aluminum, copper, nickel, titanium, magnesium, cobalt, general steel, high tensile steel, boron steel, nickel steel, magnesium steel, titanium steel, cobalt steel Characterized in that made.

In addition, the ionization potential layer is characterized in that the weight ratio of the wire to 0.01% ~ 5%.

1 is a conceptual diagram illustrating the metal transition mode of the volume during arc welding using argon gas as a protective gas.

Figure 2 is a conceptual diagram illustrating the metal transition mode of the volume during arc welding using carbon dioxide gas as a protective gas.

3 is a perspective view showing a welding wire according to a first embodiment of the present invention.

Figure 4 is a perspective view showing a welding wire according to a second embodiment of the present invention.

5 is a perspective view showing a welding wire according to a third embodiment of the present invention.

Figure 6 is a graph showing the average number of short-circuits of the volume during arc welding of the wires of Preparation Examples 1 to 6 manufactured in the Preparation Example and the wire of the Comparative Example.

7 is a graph showing the instantaneous short circuit frequency and the normal short circuit frequency of the volume during arc welding of the wires of Preparation Examples 1 to 6 manufactured in the Preparation Example and the wire of the Comparative Example.

[Revision under Rule 91 02.11.2010]
8 is a diagram showing the results of high-speed imaging of the welding phenomenon during welding of the wires of Preparation Examples 1 to 6 and the wires of Comparative Examples.

Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the accompanying drawings, but the present invention is not limited to the embodiments shown in the drawings.

As shown therein, the welding wire of the present invention includes a core layer 10 which melts due to arc heat during welding and becomes a volume; And an ionization potential layer 30 formed on the surface of the core layer 10 and made of an element having low ionization energy.

The core layer 10 is melted by a strong arc heat received during welding to become metal vapor or droplets, and the material forming the core layer 10 is the same as or similar to the base material to be bonded. It consists of a metal alloy to determine the mechanical, chemical and physical properties of the weld metal.

The core layer 10 is one metal or two or more alloys selected from iron, aluminum, copper, nickel, titanium, magnesium, cobalt, general steel, high tensile steel, boron steel, nickel steel, magnesium steel, titanium steel, cobalt steel It may be made of a metal, the material forming the core layer 10 may be selectively used according to the material of the base material to be bonded.

Here, the ionization potential layer 30 is a low current region (transition current) using arc welding using 100% carbon dioxide gas as a protective gas, or argon gas or argon (Ar) -carbon dioxide (CO ₂ ) mixed gas as a protective gas. In the case of welding under the region, the stable metal transition mode close to the spray-type volume transition mode appears, such as when welding with argon gas as the protective gas in the transition current region or more, and the arc efficiency is increased in the transition current region or more. It is intended to allow welding at higher speeds than before.

In this ionization potential layer 30, an ionization potential layer 30 is formed on the surface of the core layer 10 by attaching an element having a low ionization energy to the surface of the core layer 10. Can be. In this case, the ionization potential layer 30 may be formed by attaching an element having the low ionization energy through electrical, chemical, or physical plating that is commonly used. In addition, in addition to plating, all known methods for attaching elements having low ionization energy to the wire surface, such as a coating method commonly used in the art, are applicable.

The element of the ionization potential layer 30 is Cs, Rb, K, Lu, Na, Ra, Li, Sm, La, Eu, Sr, In, Al, Ga, Tl, Ca, whose primary ionization energy is 7 eV or less. Gd, Yb, S, Y, V, Cr, Nb, Ti, Zr or Pt, Pd, Sc, Sn, Mg, Mn, Ge, Si, Bi whose sum of primary ionization energy and secondary ionization energy is 25 eV or less It may be composed of one or more elements selected from.

When the ionization potential layer 30 is applied to the wire for welding, the ionization potential layer 30 is easily ionized due to the low ionization energy of the elements of the ionization potential layer 30, so that the initial arc can be easily generated, and the arc is stably Because it can be formed, arc welding using 100% carbon dioxide gas as the protective gas in all current areas, or MIG using argon gas or Ar-CO ₂ mixed gas as the protective gas in low current areas (below the transition current area) Spray type volume transfer mode can be displayed even in metal inert gas) and metal active gas (MAG) welding.

In addition, when welding is performed above the transition region current, high-speed welding with a higher speed than the conventional one is possible due to the increase in the arc efficiency, thereby greatly improving productivity.

In this case, the ionization potential layer 30 preferably has a weight ratio of 0.01% to 5% of the total wire.

If the weight ratio of the ionization potential layer 30 is less than 0.01%, in the case of general CO ₂ welding using carbon dioxide as a protective gas, a lot of rebound transition modes occur, so that arc stabilization and welding quality are not improved. In MIG and MAG welding using Ar-CO ₂ gas, the welding speed is low and the arc control is not easy because the welding is performed by the granular volume transfer with short circuit even in the low current region (below the transition current region). When welding over the area, the arc efficiency cannot be improved. On the contrary, when the weight ratio of the ionization potential layer 30 is higher than 5%, a large problem may occur in the wire feeding ability, and it is not economical because only the plating time and the amount of elements used for plating are increased without improving the welding quality.

In addition, the weight ratio of the ionization potential layer 30 is more preferably 1% to 5% of the total wire.

In other words, the welding wire according to the present invention generates a stable arc through the low ionization energy of the ionization potential layer, so that 100% carbon dioxide gas is used as the protective gas during the arc welding, the stable arc and metal volume transition in the entire current range. Mode can be formed, and even when welding using argon gas or Ar-CO ₂ mixed gas as a protective gas in the low current region (below the transition current region), as when welding using Ar gas above the transition current region The stable metal transition mode can be shown, and the arc efficiency is higher than the existing one in the transition current region, enabling high-speed welding, and economical welding can be performed, and welding can be performed with little occurrence of short circuit and spatter. Welding workability and welding quality can be improved, and the working environment can be improved.

The welding wire according to the present invention is applicable to all conventional welding wires that are generally used, including solid wires, and to the flux cored wires by attaching an element having low ionization energy to the surface or the inner surface of the strip, thereby providing an arc mode. By changing the arc stability can be improved, thereby improving the workability and welding quality.

4 is a perspective view showing a welding wire according to a second embodiment of the present invention, Figure 5 is a perspective view showing a welding wire according to a third embodiment of the present invention.

As shown therein, between the core layer 10 and the ionization potential layer 30, or on the surface of the ionization potential layer 30, a conductive layer 20 for transferring electricity flowing through the wire to the core layer 10 is provided. It is preferable to form more.

The conductive layer 20 is a portion to facilitate the transfer of electricity flowing to the wire surface to the core layer 10, the conductive layer 20 is ionization potential layer 30 is made of a metal having excellent electrical conductivity, such as copper May be formed between the core layer 10 and the ionization dislocation layer 30, as shown in FIG. 4, as shown in FIG. It may be formed by attaching a metal having excellent electrical conductivity to the surface of the ionization potential layer 30.

The conductive layer 20 may be formed by an electrical, chemical or physical plating method that is commonly used, and may also be formed through a conventional coating method.

As such, the wire for welding in which the conductive layer is formed can be easily transferred to the core layer so that welding can be made faster, and thus the welding efficiency can be increased, and as the stable arc occurs, in the above-described first embodiment As shown in FIG. 1, when the carbon dioxide gas, the argon gas, or the argon-carbon dioxide gas is used as the protective gas in the welding, the same transition mode as the case of welding using the Ar gas in the transition current region or more is shown. It is possible to reduce the occurrence of short circuit and spatter, thereby improving the welding quality.

On the other hand, in the present invention, as the fourth embodiment, a metal having conductivity in the ionization potential layer 30 of the welding wire including the core layer 10 and the ionization potential layer 30 is further formed. It can also be included.

That is, when the ionization potential layer 30 is formed, the ionization potential layer 30 is formed on the core layer 10 through plating or coating in a state in which an element having low ionization energy and a metal such as copper having excellent conductivity are mixed. ), The welding wire according to the fourth embodiment mixes a conductive metal in the ionization potential layer 30 itself so that electricity can flow to the core layer 10 well. In this case, as the metal having the conductivity, various known metals may be applied in addition to copper.

Such a welding wire is improved in conductivity to help transfer electricity to the core layer during welding, thereby improving welding efficiency.

In the following, the following experiment was conducted to prove the effect of the welding wire according to the present invention.

Indium (In) is plated on the surface of the solid wire (ER-70s G 1.2Φ) which is most used for carbon steel welding in the plating time shown in Table 1 below to form an ionization potential layer, and the ionization potential formed by the plating The weight ratio of the layers is shown in Table 1 below.

Table 1

Classification	Dislocation layer plating time (s)	Ionization Dislocation Layer Weight Ratio (%)
Preparation Example 1	5	0.47
Preparation Example 2	10	0.59
Preparation Example 3	20	0.62
Preparation Example 4	40	1.17
Preparation Example 5	60	1.40
Preparation Example 6	90	1.96
Comparative Example	0	0

Experimental Example

[Revision under Rule 91 02.11.2010]
Gas metal arc welding was carried out under the welding conditions as shown in Table 2 using a wire having an ionization potential layer formed of indium of Preparation Examples 1 to 6 manufactured in the above Preparation Example and a comparative example wire (ER-70s G 1.2Φ). In order to evaluate the welding phenomenon during welding, high-speed photography was performed using a high-speed camera, and the results are shown in FIG. 8. The results of the measurement of the number of normal short-circuit and instantaneous short-circuit were measured using an arc monitoring system. Table 3 and Figures 6 and 7 are shown.

TABLE 2

Classification	Condition
Test piece for welding	General Structural Steels (KS D 3503 (t: 10㎜))
Protective gas	Carbon dioxide (CO ₂₎ 100%
Welding current	235A
Welding voltage	24 ~ 27V
Welding speed
	30 cm / min
Contact Tip to Workpiece Distance (CTWD)	12 mm

Here, the welding current is a current region in which the metal transition mode is shown in the granular displacement mode during arc welding. In order to confirm the displacement mode of the welding wire according to the present invention, 235A was tested as the welding current.

[Revision under Rule 91 02.11.2010]
FIG. 8 shows the results of high-speed photographing of the welding phenomenon during welding. As shown in FIG. 8, when the plating is performed for more than 20 s, the weight ratio of the ionization dislocation layer becomes 1% or more, and the volume as shown in FIG. It was confirmed that the spray transition mode of appeared.

[Correction under Rule 91 02.11.2010] [deleted]

[Revision under Rule 91 02.11.2010]
Table 3, FIG. 6, and FIG. 7 show the number of short circuits of the volume measured during the arc welding experiment, respectively. As shown therein, the average number of short circuits per second and instantaneous / normal short circuit times based on the plating time of 20 s were compared. And it can be seen that significantly reduced in Preparation Examples 4 to 6 compared to Preparation Examples 1 to 3.

The more the volume short circuit occurs, the more spatter is generated, and in particular, in the case of the instantaneous short circuit, a large number of opposing spatters are generated according to the instantaneous arc pressure. It can be expected that the generation of spatters will be significantly reduced because the number of short circuits of the volume during welding is significantly reduced by the formation of the ionization dislocation layer.

TABLE 3

Classification	Average number of paragraphs	Number of short circuits	Normal short count
Preparation Example 1	51.8	221	297
Preparation Example 2	50.3	202	301
Preparation Example 3	49.0	205	285
Preparation Example 4	40.4	165	239
Preparation Example 5	39.7	169	228
Preparation Example 6	42.3	169	254
Comparative Example	50.7	211	296

The welding wire manufactured according to the present invention through the experimental results as described above, when the arc welding using 100% carbon dioxide gas as a protective gas, the transition mode of the metal transition mode through the stable arc generation in all current region As described above, Ar can be changed to a stable metal transition mode as in the case of using a protective gas, and the welding quality can be improved by reducing the number of short circuits and the generation of spatters. In addition, through the stable arc generation as described above it can be predicted that a stable metal transition mode may appear even when welding with argon gas or argon-carbon dioxide mixed gas as a protective gas in the transition current region or less.

As described above, the welding wire according to the present invention generates a stable arc through the low ionization energy of the ionization potential layer, so in the case of arc welding using 100% carbon dioxide gas as a protective gas, argon gas is in the transition current region or more. As in the case of welding using a stable arc and metal volume transition mode is formed, the use of inexpensive carbon dioxide can be economical welding, the stable metal transition mode, the occurrence of short circuit and spatter is almost It is possible to perform welding without welding, and it is possible to improve welding workability and quality of welding. Even when welding in low current area (below transition current area) using argon gas or Ar-CO ₂ mixed gas as protection gas, transition current Stable metal transition mode is achieved, such as when welding with argon gas above the zone, It is possible to improve workability and welding speed, and to weld thinner plate than before, and to increase arc efficiency when welding using argon gas or Ar-CO ₂ mixed gas as a protective gas above the transition region current. Due to this, it is possible to perform high speed welding with a higher speed than in the prior art, which greatly helps productivity improvement.

In addition, the conductive layer is formed, so that the electricity can be easily transferred to the core layer can be made faster welding has the effect of increasing the welding efficiency.

Claims

A core layer melted by arc heat during welding to become a volume;

And an ionization potential layer formed on the surface of the core layer and formed of an element having low ionization energy.
The method according to claim 1,

Welding wire, characterized in that the conductive layer for transferring the electricity flowing in the wire to the core layer between the core layer and the ionization potential layer or on the surface of the ionization potential layer.
The method according to claim 1,

Welding wire, characterized in that the ionization potential layer further comprises a conductive metal.
The method according to any one of claims 1 to 3,

The element of the ionization potential layer is Cs, Rb, K, Lu, Na, Ra, Li, Sm, La, Eu, Sr, In, Al, Ga, Tl, Ca, Gd, Yb, whose primary ionization energy is 7eV or less. S, Y, V, Cr, Nb, Ti, Zr or any one selected from Pt, Pd, Sc, Sn, Mg, Mn, Ge, Si, and Bi whose sum of primary and secondary ionization energies is 25 eV or less A welding wire comprising the above elements.
The method according to any one of claims 1 to 3,

The core layer is made of one metal or two or more alloy metals selected from iron, aluminum, copper, nickel, titanium, magnesium, cobalt, general steel, high tensile steel, boron steel, nickel steel, magnesium steel, titanium steel, cobalt steel The welding wire characterized by the above-mentioned.
The method according to claim 4,

The ionization potential layer is a welding wire, characterized in that the weight ratio of 0.01% to 5% of the total wire.