JP2835277B2 - Single-sided submerged arc welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-sided submerged arc welding method using three or more electrodes and using a flux for a backing, and more particularly, to a high welding speed of 100 to 200 cm / min. The present invention relates to an efficient single-sided submerged arc welding method.

[0002]

2. Description of the Related Art In the single-side welding method of submerged arc welding, when the welding speed is less than 100 cm / min, the front and back beads can be relatively stably formed. As shown in FIG. 5, a weld metal having a good penetration shape can be obtained. Also, in butt welding, it is necessary to apply tack welding in a groove before the main welding, but depending on the height and welding condition of this tack welding bead, single-sided submerged It does not occur that the quality of the weld bead obtained by the main welding by the arc welding is significantly impaired.

In recent years, there has been a strong demand for higher efficiency of single-sided submerged arc welding, and research on high-speed single-sided welding has been conducted. A number of research reports and proposals on speeds and welding conditions have been made for the purpose of ensuring stable formation of the back bead and securing the welding amount in welding (for example, JP-A-3-238174, JP-A-5-33).
No. 7651).

As pointed out in these research reports and publications, if the welding heat input (J / cm) is represented by (welding current × welding voltage) / welding speed, high-speed welding (1
(00 to 200 mm / min), the welding heat input necessarily decreases. Since this indicates a reduction in welding heat input per unit area in the groove, if there is a discontinuous portion in the groove or a tack weld bead that largely removes heat, it is less than 100 cm / min. Although the speed is not particularly problematic, there is a disadvantage that the tacking bead greatly affects the stable formation of the back bead particularly in the main welding.

Further, as shown in FIG. 6, when the arc passes over a tacking bead having a tacking height h, the position of the arc tip becomes higher by the height h than the normal arc length. Forming a large temporary bead is not preferable in terms of stable formation of the back bead. For this reason, as shown in FIG. 7, an undercut occurs or a bead fluctuates. Further, there arises a problem that slag is involved and that the excess of the front bead becomes excessive.

[0006] Further, in the discontinuous portion due to the tacking beads, the arc of the preceding electrode may be stopped particularly. In this case, in spite of the high-speed welding, inconveniences such as unstable formation of the back bead and arc stop occur, so that the welding work efficiency is reduced and conversely, the number of man-hours for reworking is increased compared to the conventional speed welding. become.

Further, if these problems are to be solved by reducing the height of the tacking beads as much as possible, there are the following problems. In other words, during the main welding, the tacking bead receives thermal stress that becomes a tensile force in the direction perpendicular to the welding line, but if the height of the tacking bead is low, the tacking bead breaks due to the thermal stress received during the main welding. I do. In high-speed welding, the heat input is lower than in the case of welding at a normal speed, so that the thermal stress is reduced. However, if the height of the tacking bead is too low, breakage of the tacking bead occurs. The breakage of the tack bead causes a crack in a weld metal formed by one-sided submerged arc welding.

As described above, in the conventional high-speed submerged arc welding method, various problems associated with high-speed welding have not been solved, and in order to form a stable bead and obtain a sound weld bead, Not enough.

The present invention has been made in view of the above problems, and has been made in the field of single-sided submerged arc welding using three or more electrodes.
A high efficiency single-sided submerged arc welding method that has the same stability as a weld bead obtained at a speed of less than 100 cm / min at a high welding speed of 1 min, and provides a high quality weld bead with sound penetration. The purpose is to provide.

[0010]

The single-sided submerged arc welding method according to the present invention uses at least three electrodes, and the wire diameter of the preceding first electrode is 4.0 to 4.8 m.
m, the wire diameter of the subsequent second electrode is 4.8 to 6.4
mm, and the wire diameter of the third and subsequent electrodes is 6.4 to 8.
0mm, 45 ° to 80 ° groove angle and 3 to 7m
In a single-sided submerged arc welding method for performing a Y-groove-shaped plate joint welding having a root portion of m, using a metal-based flux-cored wire, a solid wire, or a covered arc welding rod, the tacking bead length is reduced. 20mm or more,
Bead height h (mm) is 3.0 ≦ h ≦ 300 / V + 5
[However, V is a welding speed (cm / min)], and the inside of the groove is tack-welded under the condition of 100 to 200 mm.
(Cm / min).

[0011]

The present inventors have repeatedly conducted various experimental studies to solve the above-mentioned problems of the prior art, and have obtained the following findings.

In single-sided submerged arc welding using three or more electrodes, and in particular, using flux for the backing, when the welding speed is as high as 100 to 200 cm / min, a stable and sound front bead and backing are obtained. In order to obtain a bead, a conventional technique (for example, see Japanese Unexamined Patent Publication No.
No. 74, Japanese Patent Application Laid-Open No. 3-268876), it is not sufficient to just select the welding conditions, and it is affected by the shape of the temporary bead in the groove.

On the other hand, it has been found that by defining the height h of the tacking bead in the groove as in claim 1, a stable and sound welding bead can be obtained. That is, from the relationship with the welding speed V, the upper limit of the tacked bead height h is set to 30.
0 / V + 5 and the lower limit of the tacking bead height to 3.0 mm from the viewpoint of securing the strength of the tacking bead, so that even in high-speed welding, the same stability as the welding bead obtained at the conventional welding speed is obtained. And a sound high quality weld bead can be obtained.

Further, the shape of the tacking bead is such that by making the start side of the tacking bead smooth, continuous welding is possible, and the disadvantage of arc stop is eliminated. Adjustment of the height and shape of these tacked beads can be performed by a method of adjusting the welding conditions and a method of removing unnecessary portions of the tacked beads using a grinder or the like. Claim 2 defines conditions for eliminating the arc stop by making the shape of the tacking bead smooth.

Hereinafter, the reasons for limiting the numerical conditions defined in claims 1 and 2 of the present invention will be described. (1) Welding speed and tack bead height In high-speed welding, if the tack welding performed in the groove to be welded is processed under the same conditions as the conventional speed, the stability of the back bead is remarkably increased. make worse. The inventor of the present application has found that the unstable portion of the back bead almost coincides with the temporary attachment portion in the groove, and the instability of the back bead is caused by the endothermic heat of the arc by the temporary bead, remelting, and arc length. Was found to be caused by fluctuations in For this reason, in order to obtain a stable bead shape and a sound joint, it is necessary to make the shape of the tacked bead appropriate.

As a result of examining the welding quality by variously changing the welding speed and the tacking height, a correlation was found between the welding speed and the tacking height and the welding quality. That is, FIG. 1 shows that when the welding speed is 100 to 200 cm / min, the horizontal axis indicates the welding speed, and the vertical axis indicates the height of the temporary bead, and a stable bead shape and sound penetration are obtained. FIG. 4 is a graph diagram in which objects are represented by ○ and those which are not are represented by X. FIG.
As shown in the figure, when the tacking height h is a line segment represented by h = 300 / V + 5 or less, a weld metal having a stable bead shape and a sound penetration shape can be obtained. If the upper limit of the tacking height is exceeded, an undercut of the back bead occurs, the bead fluctuates, and the weld metal formed by the preceding electrode rises to near the surface of the steel sheet, and the subsequent bead is formed. Sufficient penetration at the electrode is not obtained, and slag entrainment and cracking occur.

On the other hand, the lower limit of the tacking height h requires a tacking bead height that can withstand thermal stress, and as a result, the lower limit of the tacking height is 3.0 mm.

The welding conditions are preferably such that the sum of the current values of the first electrode and the second electrode is in the range of 2000 to 3000 (A).

(2) Temporary bead shape The temporary bead provided in the groove differs in the processing of the start side or the end of the bead depending on the operator. In tack bead shown in Figure 3, the ratio L2 / L1 of the length L2 of the parallel portion of the tack bead upper with respect to the weld length L 1 of the tack welding is more than 0.8, both end portions of the tack beads rapidly , Resulting in a very discontinuous weld line. For this reason, the arc of the leading electrode may become unstable, and the arc may stop due to rapid arc fluctuation. Therefore, to obtain a smooth tacked bead shape, the ratio L2
/ L1 is preferably set to 0.8 or less.

As shown in FIG. 4, the sectional shape of the tacking bead is such that the height difference h1 between the apex of the bead and the point where the bead contacts the groove surface is 1.5 mm or less. It is desirable that

The tack welding may be performed using any of a metal flux-cored wire, a solid wire, a coated arc welding rod, a titania-based flux-cored wire, and the like.
The use of a slag is preferable because the amount of slag is small.

(3) Groove shape (length of root portion and groove angle) The groove shape of the butt portion has a great influence on the stability and penetration of the front bead and the back bead formed by single-sided submerged arc welding. .

In single-sided submerged arc welding, a Y-shaped groove shape is most preferable in order to obtain stable front and back beads and sound penetration. As shown in FIG. 2, the root portion of the Y-shaped groove includes the current, voltage,
Since the speed is affected, if the root portion exceeds 7 mm, it is difficult to form a stable back bead. On the other hand, keeping the root portion as low as possible makes it impossible to secure the accuracy of the root portion, and similarly, it is difficult to form a stable back bead. For this reason, it is necessary to limit the root portion to 3 to 7 mm, whereby a stable back bead is formed.

Since the groove angle affects the formation of the front bead, the penetration shape and the amount of welding, a groove having an angle exceeding 80 ° has a large inner cross-sectional area, requires a larger amount of welding, and has a high speed. Not suitable for welding. On the other hand, if the angle is less than 45 °, the point at which an arc is generated becomes too high, which is not preferable from the viewpoint of ensuring stable formation of the back bead and a sound penetration shape. Therefore, the groove angle is 45
To 80 °, which provides a stable back
Front bead and sound penetration are obtained.

(4) The wire diameter of the first electrode, the second electrode, the third electrode and, if present, the electrode following the third electrode In the high-speed single-sided submerged arc welding method according to the present invention, the first electrode and the first electrode A sound back bead is secured by the two electrodes, and a necessary welding amount is obtained. However, when the wire diameter of the preceding first electrode is less than 4.0 mm, the current range that can be used properly is narrow, so that
In high-speed welding at 0 cm / min or more, it is difficult to stably melt the steel sheet backside. On the other hand, if the wire diameter of the first electrode exceeds 4.8 mm, an extremely high current is required to melt the steel sheet backside, and the arc is spread too much, so that the flow width becomes large,
As a result, the back bead width becomes excessively large. Therefore, the wire diameter of the first electrode needs to be 4.0 to 4.8 mm.

When the wire diameter of the second electrode is less than 4.8 mm, the concentration of the arc is too good, and the excess bead of the back bead becomes too large, and the spread of the arc is bad. The width cannot be secured, and the bead width becomes unstable. On the other hand, the wire diameter of the second electrode is 6.4 mm
When the value exceeds, the arc concentration deteriorates, and it is not possible to secure a proper extra height of the back bead, and the arc is too wide, so that undercut easily occurs. Therefore, the wire diameter of the second electrode needs to be 4.8 to 6.4 mm.

If there is a third electrode and an electrode subsequent to the third electrode, the wire diameter of these electrodes including the third and subsequent electrodes is 6.4 to 8.0 mm.
When the wire diameter of these electrodes is less than 6.4 mm, a sound front bead width cannot be secured due to poor arc spread in high-speed welding, and bead stability is poor.
Further, when the wire diameter of these electrodes exceeds 8.0 mm, the concentration of the arc deteriorates, so that it is impossible to secure a sufficient penetration depth without the risk of causing vertical cracks. Therefore, the wire diameter of the third electrode and the electrode following the third electrode needs to be 6.4 to 8.0 mm.

(5) Temporary bead length The temporary weld bead in the groove is used to reduce the gap between the butted plates and obtain a sound bead shape and penetration in one-sided submerged arc welding. Depending on the shape of the tack weld bead, it becomes an obstacle in one-sided submerged arc welding (main welding). After the tack weld, the bead is formed into an appropriate shape by a blinder, or the tack weld method is used. This problem can be solved by appropriately controlling the conditions (1) and (2) and processing the tacked beads into a predetermined shape.

On the other hand, if the temporary bead is applied to the entire length of the welding line to be subjected to the single-sided submerged arc welding, no inconvenience occurs if the shape is appropriate. . However, the tacking bead length is 20mm
If shorter, single-sided submerged arc welding (main welding)
The temporary bead may be destroyed by the thermal stress (tensile force in the direction perpendicular to the welding line) generated by the welding. Then,
When the tack bead is broken, the plate undergoes rapid deformation, and cracks occur in the weld metal. For this reason, it is necessary to set the temporary bead length in the groove to 20 mm or more. The interval between the tacking beads is desirably 2000 mm or less.

[0030]

Next, examples of the present invention will be described in comparison with comparative examples. The steel sheet shown in Table 1 below was replaced with the steel sheet shown in Table 2 below.
And the flux shown in Table 3 below was used to perform single-sided submerged arc welding. The welding test conditions are shown in Table 4 (Example) and Table 5 (Comparative Example). Table 6 (Examples) and Table 7 (Comparative Examples) below show the quality of the welds obtained by this welding test.

[0031]

[Table 1] ┌────┬─────────┬────────────────┐ │ │ │ Chemical composition of steel sheet (% by weight) │ │ Steel type │ thickness │ │ │ (mm) │ C │ Si │ Mn │ P │ S │ ├────┼────── ───┼──┼──┼──┼───┼───┤ │SM400 │ 12~27 │0.11│0.28│1.06│ 0.015│ 0.007│ └────┴────── ───┴──┴──┴──┴───┴───┘

[0032]

[Table 2]

[0033]

Table 3 (Part 1) ┌─────┬────────────────────────┐ │ │ Chemical composition of flux (weight %) │ │ Particle size ├────┬────┬───┬─┬───┬────┤ │ mesh │ SiO ₂ │ Al ₂ O ₃ │ CaO │ F │ MgO │ TiO ₂ │ ├─────┼────┼────┼───┼─┼───┼────┤ │10 × 48│ 11 │ 7 │ 9 │ 3│ 24 │ 13 │ └─────┴────┴────┴───┴─┴───┴────┘ Table 3 (Part 2) ┌─────┬─────化学 │ │ Chemical composition of flux (% by weight) │ │ Particle size ├────┬────┬──────┤ │ Mesh │ Na ₂ O │ Fe │ Other (*) │ ├─────┼────┼────┼──────┤ │ 1 × 48│ 2 │ 15 │ 16 │ └─────┴────┴────┴──────┘ (*) CO 2, B 2 O 3, Fe-Si, Fe- Mn, etc.

[0034]

[Table 4] Table 4 (Part 1) ┌───┬──┬──┬──┬──┬──┬──┬──┬──┬──┬───┐ │ │ Thickness │groove │ electrode │ diameter │ current │ voltage │ welding │ temporary │ temporary │ L2 │ │ │ │ shape │ │ │ │ │ speed │ length │ / L1 │ │ │ (mm) │ │ │ ( (mm) │ (A) │ (V) │ (cm │ (mm) │ (mm) │ │ │Test NO│ │ │ │ │ │ │ / min) │ │ │ │ ├─┬─┼──┼── │ │ │ │ │ │ │ L │ 4.8 │ 1400 │ 38 │ │ │ │ │ │ │ │ 1 │ 13 │ 60 ° │ T1 │ 6.4│ 900│ 48 │ 150│ 6.0│ 30 │ 0.6 │ │ │ │ │ │Y3│ T2 │ 6.4│ 900│ 50 │ │ │ │ │ ├─┼──┼──┼──┼─ ├─┼──┼──┼──┼─ ─┼──┼──┼──┼──┼──┼───┤ │ Actual │ │ │ │ L │ 4.8 │ 1500 │ 38 │ │ │ │ │ │ │ │ 2 │ 25 │ 50 │ T1 │ 4.8 │ 1300 │ 45 │ 1 00│ 7.0│ 40 │ 0.7 │ │ Example│ │ │ │Y5│ T2 │ 6.4│1200│ 50 │ │ │ │ │ │ ├─┼──┼──┼──┼──┼──┼──┼─ │ │ │ │ │ │ │ L │ 4.8 │ 1500 │ 38 │ │ │ │ │ │ │ │ 3 │ 16 │ 60 │ T1 │ 4.8 │ 1100 │ 48 │ 130 │ 5.5 │ 25 │ 0.7 │ │ │ │ │ │Y3│ T2 │ 6.4│1200│ 50 │ │ │ │ │ │ │ ├─┼──┼──┼──┼──┼──┼──┼──┼──┼ ──┼───┤ │ │ │ │ │ │ L │ 4.8 │ 1500 │ 36 │ │ │ │ │ │ │ │ 4 │ 18 │ 50 │ T1 │ 4.8 │ 1200 │ 46 │ 115 │ 6.5 │ 30 │ 0.8 │ │ │ │ │Y4│ T2 │ 6.4│1100│ 50 │ │ │ │ │ │ │ ├─┼──┼──┼──┼──┼──┼──┼──┼──┼──┼── ─┤ │ │ │ │ │ │ L │ 4.8 │ │ │ 36 │ │ │ │ │ │ │ │ 5 │ 20 │ 45 │ T1 │ 4.8 │ 1300 │ 46 │ 110 │ 6.0 │ 50 │ 0.7 │ │ │ │Y4│ T2 │ 6.4│1100│ 50 │ │ │ │ │ └─┴─┴──┴──┴──┴──┴──┴──┴──┴──┴──┴─ └─┴─┴──┴──┴──┴──┴──┴──┴──┴──┴──┴─ ──┘ Table 4 (Part 2) ┌───┬──┬──┬──┬──┬──┬──┬──┬──┬──┬───┐ │ │Sheet thickness│ Groove │ electrode │ diameter │ current │ voltage │ welding │ temporary │ temporary │ L2 │ │ │ │ shape │ │ │ │ │ speed │ height │ length │ / L1 │ │ │ (mm) │ │ │ (mm ) │ (A) │ (V) │ (cm │ (mm) │ (mm) │ │ │Test NO│ │ │ │ │ │ │ / min) │ │ │ │ ├─┬─┼──┼──┼ ──┼──┼──┼──┼──┼──┼──┼───┤ │ │ │ │ │ │ L │ 4.8 │ 1350 │ 38 │ │ │ │ │ │ │ │ 6 │ 14 │ 70 ° │ T1 │ 6.4 │ 900 │ 48 │ 140 │ 5.5 │ 35 │ 0.6 │ │ │ │ │ │ Y7 │ T2 │ 6.4 │ 1000 │ 50 │ │ │ │ │ │ ├─┼──┼──┼──┼── ┼──┼── │ │ Actual │ │ │ │ L │ 4.8 │ 1500 │ 38 │ │ │ │ │ │ │ │ 7 │ 27 │ 50 │ T1 │ 4.8 │ 1300 │ 46 │ 100 │ 7.5 │ 20 │ 0.8 │ │ Example │ │ │ Y7 │ T2 │ 8.0 │ 1300 │ 50 │ │ │ │ │ │ ├─┼──┼──┼──┼──┼──┼──┼── │ │ │ │ │ │ L │ 4.8 │ │ │ 38 │ │ │ │ │ │ │ │ 8 │ 12 │ 80 │ T1 │ 4.8 │ 1200 │ 42 │ 200 │ 5.0 │ 30 │ 0.6 │ │ │ │ │ │Y3│ T2 │ 6.4│ 800│ 45 │ │ │ │ │ │ │ │ │ │ │ T3 │ 6.4│1000│ 50 │ │ │ │ │ ├─┼──┼──┼── ├─┼──┼──┼── ├─┼──┼──┼── │ │ │ │ │ │ L │ 4.8│1500│ 36 │ │ │ │ │ │ │ │ 9│ 21 │50 ° │ T1 │ 6.4 │ 1250 │ 42 │ 130 │ 5.5 │ 30 │ 0.7 │ │ │ │ │ │ Y4 │ T2 │ 6.4 │ 800 │ 45 │ │ │ │ │ │ │ │ │ │ T3 │ 6.4│1150│ 98 │ │ │ │ │ └─┴─┴──┴──┴──┴──┴──┴──┴──┴──┴──┴───┘ ４ Table 4 3) ┌───┬──┬──┬──┬──┬──┬──┬──┬──┬──┬───┐ │ │ thickness │ groove │ electrode │ diameter │ Current | Voltage | Welding | Temporary | Temporary | L2 │ │ │ │ Shape │ │ │ │ │ Speed │ Height │ Length │ / L1 │ │ │ (mm) │ │ (mm) │ (A) │ ( V) │ (cm │ (mm) │ (mm) │ │ │Test NO│ │ │ │ │ │ │ │ / min) │ │ │ │ ├─┬─┼──┼──┼──┼──┼─ ─┼──┼──┼──┼──┼───┤ │ │ │ │ │ │ L │ 4.8 │ 1500 │ 38 │ │ │ │ │ │ │ │ 10 │ 25 │ 50 │ T1 │ 4.8 │ 1300 │ 42 │ 100 │ 6.0 │ 40 │ 0.5 │ │ Actual │ │ │ Y5 │ T2 │ 6.4 │ 1050 │ 45 │ │ │ │ │ │ │ │ │ │ │ T3 │ 6.4 │ 1200 │ 48 │ │ │ │ │ │ Example ├ ─┼──┼─ ┼──┼──┼──┼──┼──┼──┼──┼───┤ │ │ │ │ │ │ L │ 4.8 │ 1450 │ 36 │ │ │ │ │ │ │ │ 11 │ 19 │ 50 ° │T1│6.4│1200│42│140│5.0│45│0.9││││││││Y3│T2│6.4│900│45││││││││││││T3│6.4│1100│48││││ │ │ │ └─┴─┴──┴──┴──┴──┴──┴──┴──┴──┴──┴───┘

[0035]

[Table 5] Table 5 (Part 1) ┌───┬──┬──┬──┬──┬──┬──┬──┬──┬──┬───┐ │ │Sheet thickness │groove │ electrode │ diameter │ current │ voltage │ welding │ temporary │ temporary │ L2 │ │ │ │ shape │ │ │ │ │ speed │ length │ / L1 │ │ │ (mm) │ │ │ ( (mm) │ (A) │ (V) │ (cm │ (mm) │ (mm) │ │ │Test NO│ │ │ │ │ │ │ / min) │ │ │ │ ├─┬─┼──┼── │ │ │ │ │ │ │ L │ 4.8 │ 1500 │ 36 │ │ │ │ │ │ │ │ 1 │ 12 │ 70 ° │ T1 │ 6.4│1000│ 42 │ 170│ 7.0│ 50 │ 0.6 │ │ │ │ │ │ Y3│ T2 │ 6.4│ 900│ 48 │ │ │ │ │ │ ├─┼──┼──┼──┼─ ├─┼──┼──┼──┼─ │ │ │ │ │ │ L │ 4.8 │ 1500 │ 36 │ │ │ │ │ │ │ │ 2 │ 20 │ 85 │ T1 │ 4.8 │1300│ 40 │ 110 6.0│ 40 │ 0.7 │ │ │ │ │ │Y5│ T2 │ 6.4│1300│ 46 │ │ │ │ │ │ Ratio ├─┼──┼──┼──┼──┼──┼──┼──┼ │ │ comparison │ │ │ │ L │ 4.8 │ 1300 │ 34 │ │ │ │ │ │ │ │ │ 3 │ 14 │ 45 │ T1 │ 4.8 │ 1000 │ 42 │ 160 │ 6.5 │ 15 │ 0.5 │ │ │ │ │ │Y3│ T2 │ 6.4│ 900│ 50 │ │ │ │ │ │ ├─┼──┼──┼──┼──┼──┼──┼──┼──┼ ──┼───┤ │ │ │ │ │ │ L │ 4.8 │ 1500 │ 34 │ │ │ │ │ │ │ │ 4 │ 20 │ 40 │ T1 │ 6.4 │ 1300 │ 40 │ 100 │ 5.0 │ 50 │ 0.6 │ │ │ │ │Y6│ T2 │ 6.4│1200│ 48 │ │ │ │ │ │ └─┴─┴──┴──┴──┴──┴──┴──┴──┴──┴──┴─ ──┘ Table 5 (Part 2) │ │ │Sheet thickness Groove │ electrode │ diameter │ current │ voltage │ welding │ with temporary │ with temporary │ L2 │ │ │ │ shape │ │ │ │ │ speed │ height │ length │ / L1 │ │ │ (mm ) │ │ │ (mm ) │ (A) │ (V) │ (cm │ (mm) │ (mm) │ │ │Test NO│ │ │ │ │ │ │ / min) │ │ │ │ ├─┬─┼──┼──┼ ──┼──┼──┼──┼──┼──┼──┼───┤ │ │ │ │ │ │ L │ 4.8 │ 1350 │ 36 │ │ │ │ │ │ │ │ 5 │ 22 │ 60 ° │ T1 │ 6.4 │ 1200 │ 46 │ 130 │ 2.8 │ 40 │ 0.7 │ │ │ │ │ Y5 │ T2 │ 6.4 │ 1200 │ 50 │ │ │ │ │ │ ratio ├─┼──┼──┼──┼─ │ │ comparison │ │ │ │ L │ 4.8 │ 1400 │ 34 │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ T1 │ 4.0│1250│ 42 │ 125│ 7.0│ 30 │ 0.4 │ │ │ │ │ │Y3│ T2 │ 6.4│1200│ 48 │ │ │ │ │ │ ├─┼──┼──┼──┼──┼─ ─┼ │ │ │ │ │ │ L │ 4.8│1500│ 36 │ │ │ │ │ │ │ │ 7│ 12 │70 ° │ T1 │ 4.8│1400│ 44 │ 210 │ 5.0│ 40 │ 0.9 │ │ │ │ │ Y3 │ T2 │ 6.4 │ 800 │ 48 │ │ │ │ │ │ │ │ │ │ T3 │ 6.4 │ 1000 │ 50 │ │ │ │ │ └─┴─┴──┴ └─┴─┴──┴ └─┴─┴──┴ ──┴──┴──┴──┴──┴──┴──┴──┴───┘ Table 5 (Part 3) ┌───┬──┬──┬──┬──板 │ │ Plate thickness │ Groove │ Electrode │ Diameter │ Current │ Voltage │ Welding │ Temporary │ Temporary │ L2 │ │ │ │ Shape │ │ │ │ │ speed │ height │ length │ / L1 │ │ │ (mm) │ │ │ (mm) │ (A) │ (V) │ (cm │ (mm) │ (mm) │ │ test NO │ │ │ │ │ │ │ │ / min) │ │ │ │ ├─┬─┼──┼──┼──┼──┼──┼──┼──┼──┼──┼───┤ │ │ │ │ │ L 4.8│1450│ 35 │ │ │ │ │ │ │ 8│ 14 │60 ° │ T1 │ 4.8│1200│ 42 │ 160│ 7.0│ 50 │ 0.7 │ │ Ratio │ │ │Y3│ T2 │ 6.4│ 900│ 46 │ │ │ │ │ │ comparison │ │ │ │ T3 │ 6.4 │ 1000 │ 50 │ │ │ │ │ │ │ Example ├─┼──┼──┼──┼──┼──┼──┼──┼── │ │ │ │ │ │ L │ 4.8 │ 1500 │ 34 │ │ │ │ │ │ │ │ 9 │ 20 │ 50 │ T1 │ 4.0 │ 1300 │ 42 │ 130 │ 5.5 │ 45 │ 0.6 │ │ │ │ │Y5│ T2 │ 4.0│1000│ 46 │ │ │ │ │ │ │ │ │ │ │ T3 │ 6.4│1000│ 50 │ │ │ │ │ └─┴─┴──┴──┴──┴─ ─┴──┴──┴──┴──┴──┴───┘

[0036]

[Table 6]

[0037]

[Table 7]

However, in Tables 4 and 5, the column of the groove shape is Y-shaped, and indicates the groove angle and the length of the root portion. In Tables 6 and 7, ◎ indicates extremely stable, ○ indicates stable, △ indicates slightly stable, and × indicates unstable.

In Table 5, Comparative Example 1 has a tacking height of 7
mm, the comparative example 2 has a large groove angle of 85 °, the comparative example 3 has a tacking length of 15 mm which is too short, and the comparative example 4 has a comparatively small groove angle of 40 °. In Example 5, the tacking height was as low as 2.8 mm, in Comparative Example 6, the second electrode diameter was as small as 4.0 mm, and in Comparative Example 7, the welding speed was too high and the ratio of L2 / L1 was 0.5. Comparative example 8 is a case where the tacking height is too high as 7 mm, comparative example 9 is a case where the diameters of the second electrode and the third electrode are small.

As shown in Tables 6 and 7, by satisfying the conditions defined in claim 1 of the present application, any one of the front bead shape, the penetration depth by the second and subsequent electrodes, and the stability of the back bead can be obtained. Was excellent, and neither cracking nor arc stop occurred. On the other hand, in the case of the comparative example deviating from claim 1 of the present application, any of the front bead shape, the penetration depth by the second and subsequent electrodes, and the stability of the back bead were inferior. In Comparative Examples 3 and 5, cracks occurred.

[0041]

As described above, according to the present invention,
Since the electrode diameter, groove shape, length and height of the tacking bead were appropriately set, 100 to 200 c in one-sided submerged arc welding using three or more electrodes.
High-speed welding at m / min can be performed with a welding bead stability equal to or higher than that of the conventional one and a sound penetration, and inconveniences such as cracking and arc stop can be avoided.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a graph illustrating a requirement of a temporary attachment height defined by the present invention, in which a horizontal axis represents a welding speed, and a vertical axis represents a height of a temporary attachment bead.

FIG. 2 is a diagram illustrating the requirements for a groove shape.

FIG. 3 is a diagram illustrating requirements of a tacking bead.

FIG. 4 is a view for explaining requirements of a tacking bead.

FIG. 5 is a schematic view showing a bead shape of a welded portion.

FIG. 6 is a diagram illustrating a problem due to the shape of a tacking bead.

FIG. 7 is a schematic diagram illustrating undercut and slag entrainment.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23K 9/18 B23K 9/235

Claims (2)

(57) [Claims] 1. The method according to claim 1, wherein at least three electrodes are used, and the wire diameter of the preceding first electrode is 4.0 to 4.8 mm, the wire diameter of the subsequent second electrode is 4.8 to 6.4 mm, and the third electrode is
A single-sided submerged arc for welding a Y-shaped groove having a groove angle of 45 ° to 80 ° and a root portion of 3 to 7 mm with a wire diameter of the electrode and subsequent electrodes of 6.4 to 8.0 mm. In the welding method, the tacked bead length is 20 mm or more, and the bead height h (mm) is 3.0 ≦ h ≦ 3.
After temporarily welding the inside of the groove under the condition of 00 / V + 5 [where V is the welding speed (cm / min)], the inside of the groove is 100
A single-sided submerged arc welding method, wherein the welding is performed at a speed of from 200 to 200 (cm / min). Wherein said tack welding, and characterized in that the ratio L2 / L1 of the length L2 of the parallel portion of the tack bead upper with respect to the weld length L 1 of the tack welding is carried out in 0.8 the following conditions Single sided submerged arc welding method.