JPH05261593A - Self-shielded wire for upward arc welding and procedure - Google Patents

Abstract

PURPOSE:To provide the self-shielded wire for upward arc welding having excellent welding workability (blowhole resistance, slag removability, bead appearance, arc stability, etc.) and the procedure. CONSTITUTION:This flux cored wire is constituted by filling a flux into a carbon steel sheath and contains, by the total weight of the wire, 2.5 to 6% potassium silicofluoride, 0.5 to 5% (where 1 to 10 ratio of the potassium silicofluoride/ alkaline earth carbonate), 10 to 20% iron powder, 0.01 to 0.15% C, 0.5 to 3.0% Mn and 0.05 to 1.0% Si. One or >=2 kinds of <=1% Mg, <=1% Al, <=1% Ti, <=1% Zr, <=0.1% B, <=3% Ni, <=1% Mo, <=1% Cu and <=1% Cr may be incorporated therein. A water cooled stationary type or sliding type backing strip provided with a groove for escaping slag in a groove for forming a bead is preferable as the backing strip to be used for upward arc welding by the self- shielded wire. The upward arc welding method is executed by using the backing strip and the flux cored wire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical advance automatic arc welding applied to shipbuilding, steel frame, tank construction and the like, and more particularly to a vertical advance automatic arc welding which does not require a shield gas from the outside. ..

[0002]

2. Description of the Related Art As an automatic welding method for improving vertical arc, there are electroslag welding method, gas shield arc welding method and the like. Also, using the welding equipment of the gas shield arc welding method as it is,
There is also a method of welding with a self-shielding wire that does not require shielding gas from the outside.

The welding method using the self-shielded wire is
Compared with the gas shielded arc welding method, there is no need for a shield gas from the outside, so there is no need for a shield gas supply device, and the welding device can be made compact, which is advantageous in handling.

By the way, in this welding method using the self-shielding wire, the fluidity of the slag is an extremely important factor because the narrow space surrounded by the metal fitting is welded. With a normal self-shielding wire, the viscosity of slag is generally high and the amount of slag is large, so that stable welding is difficult. Further, since the Al content is large, there is a problem in the vertical improvement automatic welding that the toughness is significantly impaired.

Conventionally, Japanese Examined Patent Publication No. 56-13553 has been proposed as a self-shielding wire for self-welding in the vertical advance process, but it has the following problems. Blowholes are easily generated at the start of an arc. The bead appearance is uneven. The peelability of the slag is poor.

It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a vertical improved arc automatic welding technique having excellent welding workability and high work efficiency.

[0007]

[Means for Solving the Problems] Needless to say, the self-shielding wire is required to have a shielding property for preventing blowholes in upright arc welding, but in order to ensure stable and efficient welding. To achieve this, proper slag amount and slag fluidity are essential. That is, if the amount of slag is too large, the molten pool will be covered and the arc will fly to the slag, and welding will not be stable. Further, when the fluidity of the slag is low, the same phenomenon as when the amount of slag is excessive is observed, and the adhesion of the slag to the bead surface becomes non-uniform, making it difficult to remove the slag and making the bead shape poor.

1. Prevention of blowholes and stability of welding Since the shield is unstable at the time of arc start, blowholes are particularly likely to occur. Although it is possible to prevent blowholes at the start of arc by adding only potassium silicofluoride, it is necessary to add a large amount. On the other hand, since the amount of slag is excessive and the fluidity is inadequate, stable welding cannot be performed. However, by using potassium silicofluoride and alkaline earth carbonate together, it becomes possible to prevent blowholes at the time of arc start and to give a proper amount of slag and fluidity, thus ensuring welding stability. .. Also, there is no need to use tabs.

2. Improvement of slag releasability and bead appearance When single addition of potassium silicofluoride is used, slag adhesion is non-uniform and small and easily broken, so bead appearance is not uniform and slag removal is not easy. .. However, when used in combination with alkaline earth carbonate, the amount of slag,
Since the fluidity and the quality of the slag are improved, the peelability of the slag and the bead appearance are improved.

Based on the above findings, further intensive research was conducted on the adjustment of the components of the flux-cored wire, and the self-shielding wire according to the present invention could be made here.

In addition, in addition, a metal fitting structure capable of properly maintaining the amount of slag in the molten pool and stabilizing welding was found, and further, a construction method using these self-shielding wires and metal fittings was also found. It is a thing.

That is, according to the present invention, in a flux-cored wire used for vertical arc welding, the carbon steel shell is filled with flux, and the weight ratio to the total weight of the wire is potassium silicofluoride: 2. 5 to 6%, alkaline earth carbonate: 0.5 to 5% (however, potassium silicofluoride / alkaline earth carbonate ratio: 1 to 10), iron powder: 10 to 20%, C: 0.0.
01-0.15%, Mn: 0.5-3.0% and Si: 0.05
.About.1.0%, and if necessary, Mg: 1% or less, Al: 1% or less, Ti: 1% or less, Zr: 1% or less, B:
0.1% or less, Ni: 3% or less, Mo: 1% or less, Cu: 1%
The present invention is directed to a self-shielding wire for vertical arc welding, characterized by containing one or more of Cr and 1% or less of Cr.

Another aspect of the present invention is a metal plate used for vertical arc welding with self-shielding wire,
The gist of the present invention is a water-cooled fixed type or sliding type metal plate, characterized in that a slag escape groove is provided in the bead forming groove.

Still another aspect of the present invention uses the flux-cored wire and the water-cooled fixed type or sliding type metal plate with a groove for slag escape, which is characterized by using self-shielding wire. It is based on the law.

The present invention will be described in more detail below.

[0015]

[Action]

First, the reason for limiting the flux component in the self-shielding wire for vertical arc welding according to the present invention will be described. The content of each component is a weight ratio with respect to the total weight of the wire.

Potassium silicofluoride: Potassium silicofluoride decomposes at a low temperature to generate gas and metal vapor, is effective in shielding the molten pool, and has the effect of increasing arc stability. However, if it is less than 2.5%, the shield of the molten pool is insufficient, blowholes are observed, and the viscosity of the slag cannot be properly maintained. If it exceeds 6%, the slag amount is excessive and stable welding is possible. Can not. Therefore, the amount of potassium silicofluoride is in the range of 2.5 to 6%.

Alkaline earth carbonate : Alkaline earth carbonate is a gas shield agent which is effective in combination with potassium silicofluoride and is extremely effective in preventing blowholes at the time of arc start. Further, the fluidity of the slag is made favorable, and a beautiful bead appearance is obtained. Furthermore, since the slag is made porous, it has the effect of improving the slag releasability.
However, if it is less than 0.5%, there is no effect in preventing blowhole generation at the time of arc start, and there is no effect in improving the bead appearance and slag peeling property. On the other hand, if it exceeds 5%, the amount of spatter is increased and stable welding cannot be performed. Therefore, the amount of alkaline earth carbonate is in the range of 0.5 to 5%.

Potassium silica fluoride / alkaline earth carbonate ratio : The ratio of potassium silica fluoride / alkaline earth carbonate is to maintain the fluidity of the slag, to give the slag releasability and a beautiful bead appearance. It is necessary to regulate it. However, the ratio is 1
If it is less than the above range, the fluidity of the slag is deteriorated, the peelability of the slag and the bead appearance are deteriorated, and if the ratio exceeds 10, the fluidity of the slag is deteriorated and stable welding cannot be performed. Therefore, the ratio of potassium silicofluoride / alkaline earth carbonate is set in the range of 1-10.

Iron powder : Iron powder is added to impart appropriate fluidity to the flux when the flux is dropped into the steel strip of the outer sheath during the production of the flux-cored wire.
However, if the amount of iron powder is less than 10%, the fluidity of the flux is poor and the flux cannot be uniformly filled.
If it exceeds%, the amount of other components added becomes relatively small,
Since the required performance will not be obtained, it is better to keep the upper limit at this level. Therefore, the amount of iron powder is set in the range of 10 to 20%.

C : C is added to adjust the mechanical properties of the welded portion, but if it is less than 0.01%, the tensile strength becomes low, while if it exceeds 0.15%, the tensile strength becomes too high. .. Therefore, the amount of C is set in the range of 0.01 to 0.15%. Note that C may be added from either the flux or the skin.

Mn : Mn is added as a deoxidizing agent and for adjusting mechanical properties, but if it is less than 0.5%, deoxidation becomes insufficient and blowholes occur, and more than 3.0%. And the tensile strength of the weld becomes too high. Therefore, the amount of Mn is made into the range of 0.5-3.0%. In addition, Mn may be added from either the flux or the skin.

Si : Si is added as a deoxidizing agent and for adjusting the mechanical properties, but if it is less than 0.05%, deoxidation becomes insufficient and blowholes occur, and more than 1.0%. And toughness decreases. Therefore, the amount of Si is 0.05 to 1.
The range is 0%. Incidentally, Si may be added from either the flux or the outer coat.

The above components are essential components, but the following M
One or more of g, Al, Ti, Zr, B, Ni, Mo, Cu and Cr can be added in an appropriate amount. When added, it can be added to either or both of the flux and the skin.

Al, Ti, Zr : Al, Ti, Zr can be added as a deoxidizing agent and a denitrifying agent, respectively. When added, if each exceeds 1%, the fluidity of the slag is impaired, which is not preferable.

Mg : Mg is an arc stabilizer and has a shielding effect, but if it exceeds 1%, the effect is saturated, so that it can be added at 1% or less.

B : B is effective in improving toughness, but is 0.1
%, The crack resistance will be impaired, so 0.1
% Or less can be added.

Ni : Ni is effective in improving toughness, but 3%
If it exceeds, the toughness is lowered, so that it can be added at 3% or less.

Mo : Mo is effective in improving tensile strength, but 1
If it exceeds 0.1%, the tensile strength becomes too high, so it can be added at 1% or less.

Cu, Cr : Cu and Cr are each effective in improving the weather resistance, but if each exceeds 1%, the tensile strength becomes too high, and therefore each can be added at 1% or less.

Depending on the case, the following components can be added as required. That is, the alkaline earth fluoride can be added in an amount of 1% or less in order to adjust the fluidity of the slag. If it exceeds 1%, the arc becomes unstable, which is not preferable. One or more metal oxides may be added in an amount of 0.6% or less in order to adjust the fluidity of the slag. If it exceeds 0.6%, the peelability of the slag becomes poor, which is not preferable.

The wire may be manufactured by a usual method. For example, the flux rate of the flux-cored wire is not particularly limited, but an appropriate flux rate is 15 to 30%. Further, since the performance of the wire is not affected by the cross-sectional shape of the wire, the shape can be appropriately adjusted.

The straps: water-cooled straps are used in the construction of stand improvement advance arc automatic welding. There are a fixed type and a sliding type as the mode of use of this pad, and there are a case where it is attached only to one side of the base material groove and a case where it is attached to both sides of the base material groove. In some cases, a movable pad is used on one side of the base material groove and a sliding pad is used on the other side. In any case, a bead forming groove is usually formed in the pad.

In particular, in the case of the automatic vertical arc welding using the self-shielding wire, since the amount of slag is generally large, the welding becomes unstable, or defects such as slag entrainment occur.

As a measure for solving these problems, the present inventor has found that the bead forming groove of the metal stopper is provided with a slag escape groove. Thereby, the amount of slag in the molten pool can be properly maintained and the welding can be stabilized. In particular, the use of the above-mentioned flux-cored wire is effective because the slag has good fluidity.

FIGS. 1 and 2, FIG. 3 and FIG. 4, FIG. 5 and FIG. 6, FIG. 7 and FIG. 8 respectively show four examples of a metal pad provided with a slag escape groove. 1 and 2 show an example in which a slag escape groove is provided over the entire length of the bead forming groove, and FIG.
And FIG. 4 shows an example in which slag escape grooves are provided at intervals in the bead forming groove, and FIGS. 5 and 6 are provided with slag escape grooves throughout the bead forming groove, but the groove width is provided at intervals. 7 and 8 show an example in which the slag escape groove is provided only near the bottom of the bead forming groove. Needless to say, the present invention is not limited to these examples.

This metal pad may be attached to one side of the groove of the base material, or may be attached to both sides of the base material. It can also be used in combination with a backing material. Further, as a welding method, there are a method using a consumable nozzle, a method using a non-consumable nozzle, a method not using a nozzle, and the like, but any of them can be applied.

Next, examples of the present invention will be shown.

[0039]

[Example] A carbon steel strip was used as an outer skin, and the outer skin was filled with flux.

[Table 1] A flux-cored wire was manufactured as a prototype. For each wire

[Table 2] Welding test under the conditions of

[Table 3] The results shown in are obtained.

From Table 3, it can be seen that good results were obtained in the inventive examples of tests No. 1 to No. 7.

On the other hand, the comparative examples of tests No. 8 to No. 13 show the following problems, respectively.

First, in No. 8, since the addition of potassium silicofluoride is small, the generation of blow holes is recognized. No. 9 lacks the stability of the arc due to the excessive addition of potassium silicofluoride.
In No. 10, the ratio of potassium silicofluoride to the alkaline earth metal carbonate is below the lower limit of the range of the present invention, so the fluidity of the slag is poor, and there are problems in the bead appearance and slag peeling.
In No. 11, since the above ratio is too large, the arc is unstable and stable welding cannot be performed. Since No. 12 has a small amount of alkaline earth metal carbonate added, blowholes are observed to occur. In No. 13, since the amount of alkaline earth carbonate added is large, arc stability is poor and spatter is often generated.

[0043]

As described in detail above, according to the present invention,
In upright arc welding with self-shielding wire, it has excellent welding workability (blowhole resistance, slag peeling property, bead appearance, arc stability, etc.), and has a higher ascending speed than electroslag welding and a higher construction efficiency. Since it has a high heat resistance and a low heat input, it is particularly suitable for welding thin plates.

[Brief description of drawings]

FIG. 1 is a front view showing an example of a water-cooled fixed type backing plate having a slag escape groove.

FIG. 2 is a bottom view of the pad shown in FIG.

FIG. 3 is a front view showing an example of a water-cooled fixed type backing plate having a slag escape groove.

4 is a cross-sectional view taken along the line AA of FIG.

FIG. 5 is a front view showing an example of a water-cooled fixed type backing plate having slag escape grooves.

6 is a cross-sectional view taken along the line AA of FIG.

FIG. 7 is a view showing an example of a water-cooled sliding type backing plate having a slag escape groove, (a) is a front view and (b) is a side view.

FIG. 8 is a bottom view of the pad shown in FIG.

FIG. 9 is a view showing the shape and dimensions of a water-cooled sliding type backing metal having grooves for slag release used in Examples, (a) being a front view,
(B) is a side view.

FIG. 10 is a bottom view of the pad shown in FIG.

FIG. 11 is a schematic explanatory view showing an upright arc welding device used in Examples.

FIG. 12 is a side view of the welding device shown in FIG. 11.

Claims (4)

[Claims] 1. A flux-cored wire for use in vertical arc welding, comprising a carbon steel shell filled with flux and having a weight ratio with respect to the total weight of the wire (hereinafter the same) of potassium fluorosilicate: 2 0.5 to 6%, alkaline earth carbonate: 0.5 to 5% (however, potassium silicofluoride / alkaline earth carbonate ratio: 1 to 10), iron powder: 10 to 20%, C: 0 .01
~ 0.15%, Mn: 0.5-3.0% and Si: 0.05-
Self-shielding wire for vertical arc welding, characterized by containing 1.0%. 2. Further, Mg: 1% or less, Al: 1% or less, T
i: 1% or less, Zr: 1% or less, B: 0.1% or less, Ni: 3%
The self-shielding wire for vertical arc welding according to claim 1, which contains one or more of Mo: 1% or less, Cu: 1% or less and Cr: 1% or less. 3. A water-cooled fixed type or sliding type metal plate in which a bead forming groove is provided with a slag escape groove in a metal plate used for vertical arc welding with a self-shielding wire. 4. A self-shield using the flux-cored wire according to claim 1 or 2, and the water-cooled fixed type or sliding type metal plate with the slag escape groove according to claim 3. Vertical arc welding method using wire.