JPH05285662A - Termination method of multi-electrode single-sided submerged arc welding method - Google Patents

Abstract

(57) [Abstract] [Objective] The present invention relates to a high-efficiency single-sided submerged arc welding method using four electrodes, and provides a termination treatment method for forming a sound bead at the end of welding. [Structure] The interval between the second and third electrodes is set to 10 by using four electrodes.
In the single-sided submerged arc welding method with a welding speed of 0 to 250 mm and a welding speed of 80 cm / min or more, the stop position of the first electrode is set 10 mm or more behind the tip of the terminal sealing bead, and the stop position of the second electrode is the first electrode stop position. Behind and
Furthermore, the 3rd electrode is 50-100mm from the 1st electrode stop position.
At the front position, the welding speed is reduced to 35 to 65%, the current of the third electrode is increased by 15 to 40%, and the stop positions of the third and fourth electrodes are changed to those of the second electrode stop position. A termination method for a multi-electrode single-sided submerged arc welding method, which is characterized in that the rear side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-electrode single-sided submerged arc welding method using four electrodes, and more specifically, a highly efficient single-sided submerged arc welding termination treatment method in which the welding speed is greatly improved as compared with the conventional method. It is about.

[0002]

2. Description of the Related Art Conventionally, a single-sided submerged arc welding method has been widely applied mainly to shipbuilding as a highly efficient welding method for thick plates. However, the level of pursuit of efficiency is becoming higher and higher, and there is a demand for a welding method in which the speed is 1.5 to 2 times higher than the conventional welding speed.

However, the conventional single-sided submerged arc welding method is disclosed in Japanese Examined Patent Publication No. 58-22572 and Japanese Examined Patent Publication No.
As disclosed in Japanese Patent Publication No. 9-38420, the welding speed is less than 80 cm / min.

On the other hand, in ordinary joint welding in which the front side and the back side are respectively welded, many multi-electrode weldings with a welding speed of 100 cm / min or more are disclosed, but this technique is directly applied to the single-sided submerged arc welding method. Is difficult. In normal multi-electrode welding, in order to secure the amount of penetration and deposition, there is no concern about burn-through even if the current is increased forcibly, and no special consideration is required for forming the back bead, so it is faster. Can be achieved relatively easily. However, in single-sided submerged arc welding, not only the front bead but also a sound back bead is required to be formed at the same time, so in order to achieve high speed, simply increase the number of electrodes and increase the current. , The back bead is too much and the bead becomes non-uniform, and in extreme cases, lateral cracking will occur. Furthermore, if the welding speed is high, the bead becomes thin, and undercut is likely to occur at the end of the back bead. In addition, due to the high speed, the solidification of the weld metal is fast, and as shown in FIG. 4 (a), the crystal growth directions (dendrites) are abutting, and the structure becomes extremely fragile.

Therefore, the inventors of the present application filed Japanese Patent Application No. 2-318.
89, Japanese Patent Application No. 2-35918, Japanese Patent Application No. 2-6525
No. 1, Japanese Patent Application No. 2-108189, Japanese Patent Application No. 2-1976
No. 11, Japanese Patent Application No. 2-229886, Japanese Patent Application No. 2-267
No. 948 and Japanese Patent Application No. 3-96168 propose a technique for increasing the speed of single-sided submerged arc welding using four or more electrodes.

However, as a result of a diligent examination after that,
In these technologies, it has become clear that there is a possibility of defective fusion at the weld end. That is, as a measure for preventing crater cracking, a terminal sealing bead (hereinafter abbreviated as a sealing bead) is formed stepwise up to the groove surface at the weld end as shown in FIG. FIG. 1 shows a two-stage sealing bead, that is, between B-C sealed to the center of the plate and between C-D sealed to the surface. Under these circumstances, welding is performed at a high speed of 80 cm / min or more, the first and second electrodes are stopped between B and C without changing the welding conditions, and then the third and fourth electrodes are connected between C and D. When stopped, not only the crater portion becomes longer, but also the crater hole portion of the first and second electrodes has less excess, and after the second electrode is stopped, two-electrode welding is performed by the third and fourth electrodes. The bead width becomes extremely narrower than before the stop position of the second electrode. Further, since the arc gouging portion remains largely when the first and second electrodes are stopped, the residual slag cannot be completely melted at the third and fourth electrodes, and fusion failure occurs at the position where the first and second electrodes are stopped. Probability is high.

The single-sided submerged arc welding method referred to here is, as shown in FIGS. 3 (a) and 3 (b), from the back surfaces of the materials 1 and 1'to be welded to each other, onto the copper metal plate 2. The backing flux 4 spread in layers or the backing flux 4 stored in the fire-resistant canvas 7 is pressed against the back surface of the material to be welded 1, 1'by a lifting mechanism such as an air hose 5 and the wire 3, flux from the front side. No. 6 is used to perform submerged arc welding, and beads are simultaneously formed on the front side and the back side of the material to be welded.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a terminal treatment method for forming a sound bead at the end of welding in the high speed single-sided submerged arc welding method using the above-mentioned four electrodes.

[0009]

Means for Solving the Problems As a result of various studies in view of the above circumstances, the present inventors have obtained the following findings. That is, in order to obtain a sound bead at the end of welding in high-speed single-sided submerged arc welding with four or more electrodes, (1) the first electrode should be stopped at a specific position (2) the stop position of the second electrode should be Being behind the first electrode (3) Decelerating the welding speed when the third electrode reaches a specific position (4) Increasing the current of the third electrode at a specific position (5) It is important that the stop positions of the third and fourth electrodes are behind the second electrode.

That is, the gist of the present invention is that, in a single-sided submerged arc welding method with a welding speed of 80 cm / min or more in which the distance between the second and third electrodes is 100 to 250 mm using four electrodes, the first electrode is used. 10mm or more behind the tip of the terminal sealing bead, and the second electrode stop position is behind the first electrode stop position, and the third electrode is 50-100mm before the first electrode stop position. ,
The welding speed is reduced to 35-65%, the current of the third electrode is increased by 15-40%, and
The termination processing method of the multi-electrode single-sided submerged arc welding method is characterized in that the stop position of the fourth electrode is behind the second electrode stop position.

[0011]

The present invention will be described in detail below. First, in the present invention, it is necessary to use four electrodes. This forms a back bead with the first and second electrodes,
It becomes possible to form a front bead with the third electrode and the fourth electrode and to secure a necessary amount of welding.

Next, the distance between the electrodes of the second to third electrodes is set to 100 to 2
It is necessary to make it 50 mm. The third and fourth electrodes are used to secure the required amount of welding, and at the same time, they melt the weld metal formed by the first and second electrodes, and as shown in FIG. It also has a role to control. However, if the gap between the second electrode and the third electrode is narrow, a so-called one pool is formed, and the arc by the third electrode reaches the lower end of the back bead, the bead is excessively generated, and the dendrite is butt-matched, resulting in a structure that is very fragile. However, if the gap between the electrodes is too wide, the slag will be completely solidified and a stable arc cannot be generated.

[Reasons for Limiting Stop Position of First Electrode] In single-sided welding using four electrodes, the roles of the first and second electrodes are:
The groove root portion is melted by the first electrode, and the molten metal generated by the first electrode is pushed down by the second electrode to form the back bead. When performing welding, an arc gouging is performed immediately below the wire to form a cavity, and molten metal is actually generated behind the wire. When the first electrode is stopped at the tip B of the sealing bead at the welding end portion shown in FIG. 1 or at a position before that, the molten metal is generated only before the sealing bead, so that the back bead is formed just before the sealing bead. The part that does not appear occurs. The size of the arc cavity is 20 mm or less even if it is large.
Therefore, the stop position of the first electrode was set 10 mm or more behind the tip of the sealing bead (D side in FIG. 1).

[Reason for Limiting Stop Position of Second Electrode] In single-sided welding using four electrodes, a back bead is formed by the first and second electrodes, and a back bead is formed by the third and fourth electrodes by the first and second electrodes. The generated slag is remelted to form surface beads. When the first electrode is 1, the current distribution of each electrode is about 0.8 for the second electrode and about 0.5 for the third and fourth electrodes.
The second electrode uses a high current value in order to obtain a stable back bead, while the third and fourth electrodes form a good surface bead without defects and keep the current value low. For this reason,
When the first and second electrodes are stopped at the same time, the gouging portion due to the arc becomes large, and the remaining slag cannot be completely melted at the third and fourth electrodes, resulting in poor fusion. Therefore, it is necessary to disperse the residual slag of the first electrode and the second electrode and melt the residual slag of the first electrode at the second electrode.
Further, in order to form a good surface bead with the third and fourth electrodes, it is also necessary to make up for the lack of extra crater holes in the first electrode with the second electrode. Therefore, the stop position of the second electrode is behind the stop position of the first electrode.

[Reason for Limiting Decelerated Speed] In the case of four-electrode welding in the sealing bead at the welding end portion shown in FIG. 1, the first and second electrodes are stopped between B and C, and then between C and D. The third and fourth electrodes are stopped in the vicinity of D. 2 between C and D
Since electrode welding is used, the bead appearance is different from that of 4-electrode welding, and the bead width is extremely narrow. In order to widen the bead width, it is effective to reduce the welding speed. Further, by reducing the welding speed, the crater length of the front bead is also shortened. However, if the welding speed is less than 35%, the speed is too slow and the bead becomes excessive. On the other hand, 65% of welding speed
If it is over, the speed is too fast to obtain a bead width equivalent to 4 electrodes. Therefore, the welding speed of the terminal treatment is set to 35 to 65% of the welding speed up to that point.

[Reason for limiting current increase amount of third electrode] In single-sided welding of four electrodes, the third and fourth electrodes remelt the slag generated by the first and second electrodes to form a front bead. It is the third electrode that mainly melts the solidified slag, but as described above, the current value of the third electrode is set to be relatively low. Therefore, it is difficult to completely melt the residual slag in the crater portion of the second electrode with the current value as it is. Therefore, it is necessary to increase the current of the third electrode. At that time, 15
If it is less than%, it is difficult to completely melt the residual slag of the second electrode. On the other hand, when the current exceeds 40%, the arc reaches the lower end of the back bead, which adversely affects the back bead as described above. Therefore, the current of the third electrode is increased by 15 to 40% of the current value so far.

[Reason for Limiting Deceleration Position and Current Increasing Position of Third Electrode] In the case of four-electrode welding in the sealing bead at the welding end portion shown in FIG. 1, the first and second electrodes are stopped between B and C. Then, the third and fourth electrodes are stopped in the vicinity of D between C and D. Since two-electrode welding is performed between C and D, the bead width is extremely narrower than in four-electrode welding. In order to widen the bead width, it is effective to reduce the welding speed, but the position to reduce the speed must be performed before the two-electrode welding. This is because the molten metal is generated behind the wire as described above, but since the arcs of the first and second electrodes are cut off at the terminal end, the supply of metal is lost, so the excess amount of the crater approaches the terminal end. Decrease as time goes by. That is, the crater created by the first and second electrodes has a smaller amount of build-up as it approaches the terminal end, and when decelerating from the position where the first electrode is stopped, the width of the front bead gradually narrows and the decelerated position is reduced. Becomes extremely thicker. Therefore, the deceleration position must be set before the 2-electrode welding. As a result of examining the crater length formed by the first and second electrodes, the present inventors found that the maximum crater length was about 200.
It was mm. In addition, the amount of surplus starts to run short at about half the position of the crater. Therefore, the deceleration needs to be at a position 100 mm or less from the position where the first electrode is stopped. However, when decelerating from the stop position of the first electrode to less than 50 mm, the width of the front bead becomes gradually narrow and becomes extremely thick from the decelerated position. Therefore, in the deceleration position, the third electrode is the first
The position was reached 50 to 100 mm before the electrode stop position.

The third electrode mainly remelts the slag generated and solidified by the first and second electrodes. When the welding speed is reduced, the time until the slag of the first and second electrodes is remelted becomes long, and the solidification of the slag progresses. For this reason, at a relatively low set current value of the third electrode, the slag at the bead toe ends of the first and second electrodes cannot be completely melted, resulting in poor fusion. Therefore, the position where the current of the third electrode is increased is the position where the welding speed is reduced.

[Reason for Limiting Stop Positions of Third and Fourth Electrodes]
As described above, the first and second electrodes use a high current value in order to obtain a stable back bead, while the third and fourth electrodes are
The current value is kept low in order to form good surface beads without defects. The residual slag of the first electrode is melted at the second electrode, and the insufficient swelling of the crater hole portion is also compensated by the second electrode. Similarly,
In order to form a good surface bead by compensating for the melting of the residual slag of the second electrode and the insufficient buildup of the crater hole, the third, fourth
Regarding the stop position of the electrode, the stop position of the second electrode was set backward.

By the way, the welding method of the present invention is a single-sided submerged arc welding method.
Although a backing flux and an electrode wire are required, the composition of these welding materials is not particularly limited as long as a proper weld metal suitable for the purpose can be obtained.

That is, as the front side flux, Si
Metal oxides such as O ₂ , Al ₂ O ₃ , TiO ₂ , MnO and MgO, metal fluorides such as CaF ₂ and MgF ₂ , CaCO
Metallic carbonates such as ₃ , deoxidizing agents such as Si and Mn, Ni and Mo
A flux prepared by appropriately mixing an alloying agent such as the above or iron powder may be used. The flux type may be either melt type or bond type flux. The same applies to the backing flux.

Although the electrode wire is selected in relation to the flux composition, Mn: 0.3 to 3.5%, M
A wire containing one or two or more of o: 0.10 to 1.0% and Ni: 0.5 to 5% is preferable for securing strength and toughness.

The present invention has been described in detail above, but in order to further clarify the effects of the present invention, examples will be described below.

[0024]

EXAMPLES For the steel plates shown in Table 1, the wires of Table 2 and Table 3 were used.
Using the backing flux of Table 4,
Twelve types of single-sided submerged arc welding were performed. After the raw material powder was granulated using water glass, the flux in Table 3 was
Bond flux baked in a rotary kiln under the conditions of 400 ° C x 120 min, the finished flux particle size is 1
The particles were sized with 2 × 100 mesh. In addition, the backing flux in Table 4 is a bond type flux which is a backing flux used in combination with copper and metal shown in FIG. The phenol resin was dissolved in alcohol as a solvent to prepare a mucus, which was then coated on the flux particles.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

Table 5 shows the welding results in the examples of the present invention. No. which is an example of the present invention. Nos. 1 to 4 were able to obtain good welding results due to the effects of the present invention. In the cases of 5 to 8, as described in the column of welding result, satisfactory bead formation was not possible.

In Table 5, the groove shape used was that shown in FIG. t is the thickness of the test plate, d is the root face, and θ is the groove angle. The wire diameter is 4.8 for the first electrode.
mmφ, second electrode 6.4 mmφ, third electrode 6.4 mmφ, fourth
Electrode 6.4mmφ, welding voltage is 1st electrode 35V, 2nd
They are an electrode 40V, a third electrode 40V, and a fourth electrode 45V.

[0031]

[Table 5]

[0032]

[Table 6]

[0033]

[Table 7]

[0034]

According to the present invention, in high-speed single-sided submerged arc welding using four electrodes, it is possible to obtain a sound bead having no defects such as defective fusion at the welding end portion.

[Brief description of drawings]

1A and 1B are views for explaining a sealing bead at a terminal end of a welded portion.

FIG. 2 is a front view showing a groove shape used in an example of the present invention.

3 (a) and 3 (b) are front views for explaining a one-sided submerged arc welding method.

4 (a) and 4 (b) are front views for explaining the direction of a dendrite of weld metal.

[Explanation of symbols]

 1,1 'Welded material 2 Copper alloy 3 Electrode wire 4 Backing flux 5 Air hose 6 Flux 7 Fireproof campus

Claims (1)

[Claims] 1. In a single-sided submerged arc welding method with a welding speed of 80 cm / min or more in which the distance between the second and third electrodes is 100 to 250 mm using four electrodes, the stop position of the first electrode is the terminal end of the sealing bead. From the first electrode stop position to the rear side of the first electrode stop position by 10 mm or more from the first electrode stop position.
Welding speed 35-65 at the position before 00mm
While decelerating to 15%, the current of the third electrode is 15-40%
A termination treatment method for a multi-electrode single-sided submerged arc welding method, characterized in that the stop positions of the third and fourth electrodes are increased and the stop positions are behind the second electrode stop position.