JPH08257753A - One side submerged arc welding method - Google Patents

Abstract

PURPOSE: To provide one side submerged arc welding capable of obtaining sound weld zone up to joint end part by high speed one side submerged arc welding. CONSTITUTION: In executing one side submerged arc welding with a multi- electrode, the welding condition of most preceding first electrode is set to 4.0-4.8mm electrode diameter, 1200-1700A electric current, 30-40V voltage and >=90cm/min welding speed. Further, the end plate mounted to joint end part is laid so that a groove bottom part 3 arranged to an object to be welded 1 is come in contact with the end plate and a height from the groove bottom part 3 of object to be welded to the upper face of end plate at the boundary between the object to be welded and end plate is set to <16mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-efficiency one-sided submerged arc welding method for performing one-sided submerged arc welding at a high welding speed of 90 cm / min or more.

[0002]

2. Description of the Related Art In double-sided welding, many multi-electrode welding methods of 1.0 m / min or more have been proposed, and there are many reports of construction results. In the normal multi-electrode welding of both sides of one layer, it is sufficient to secure a penetration depth of about half of the plate thickness, and high-speed welding can be performed relatively easily. In addition, in single-sided submerged arc welding, recently, a technique for performing high-speed welding by improving the working conditions has been reported (JP-A-3-23817).
4, JP-A-3-2696).

[0003]

However, increasing the welding speed in single-sided welding still has many problems. In single-sided welding, since it is necessary to weld from the surface to the back bead at the same time, when the welding speed becomes high, the cooling rate of the molten pool becomes high even when a large current is used. Therefore, it is difficult to stably form the back bead because the solidification rate of the molten metal is also high. Further, since the moving speed of the arc is high, if the arc generation point changes greatly, the arc length becomes unstable and it becomes impossible to continuously and stably form the molten pool. Especially in the case of single-sided submerged arc welding, at the end of normal welding, move the end part (crater) to the end plate of the same thickness as the material to be welded attached to the end of the material to be welded (hereinafter referred to as tab plate). Although the welding is completed, in high-speed single-sided submerged arc welding in which the welding speed is 90 cm / min or more, the arc generation point changes abruptly when the arc moves from the joint end to the tab plate. There is a problem that the preceding first electrode is short-circuited or the penetration shape is discontinuous, and cracks occur in the weld line direction of the weld metal at the final end of the joint.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a single-sided submerged arc welding method capable of obtaining a sound welded portion up to the end of a joint by high-speed single-sided submerged arc welding. And

[0005]

In the method for single-sided submerged arc welding according to the present invention, in the method for single-sided submerged arc welding with multiple electrodes, the most advanced welding condition for the first electrode is electrode diameter: 4.0-4. 0.8 mm, current: 1200-
1700A, voltage: 30-40V, welding speed: 90cm /
The end plate attached to the end of the joint is arranged so that the groove bottom provided on the material to be welded and the end plate contact each other, and the groove bottom of the material to be welded at the boundary between the material to be welded and the end plate. It is characterized in that the height from to the upper surface of the end plate is less than 16 mm.

[0006]

The present inventors have obtained the following findings as a result of repeating various experimental studies in order to obtain a sound welded portion up to the joint end portion by high-speed single-sided submerged arc welding. That is, 9
In order to secure a stable back bead at a high speed of 0 cm / min or more, the electrode diameter of the most preceding first electrode is 4.0 to 4.
It is necessary to maintain the arc concentration by setting it to 8 mm, setting the current to a high current of 1200 to 1700 A, and setting the voltage to the range of 30 to 40 V.

However, when the arc moves from the joint end portion to the tab plate under such welding conditions, the arc generation point suddenly changes from the groove bottom of the material to be welded to the tab plate.
The arc length cannot be controlled and a short circuit occurs, or even if the short circuit does not occur, the arc point changes abruptly, resulting in discontinuity of melting and cracking in the weld line direction of the weld metal at the final end of the joint. In order to prevent this, the end plate attached to the joint end part for the purpose of welding end part treatment (crater treatment) is arranged so that the groove bottom provided on the material to be welded and at least the end part of the end plate are in contact with each other. Then, as the end plate, welding is performed using a material having a height from the groove bottom of the material to be welded to the upper surface of the end plate of less than 16 mm at the boundary between the material to be welded. As a result, a sound weld is obtained up to the end of the joint.

Next, the reason for limiting the numerical values of the welding conditions in the present invention will be described. In high-speed single-sided submerged arc welding method in a wire diameter present invention a method of the first electrode, to the first electrode to ensure a healthy back bead, stably melted to the steel plate back surface, and of obtaining the required deposition rate It has an action, but if the wire diameter is less than 4.0 mm, the current range that can be properly used is low, so 90c
In high-speed welding of m / min or more, it is difficult to stably melt the back surface of the steel sheet. On the contrary, if the wire diameter of the first electrode exceeds 4.8 mm, an extremely high current is required to melt the back surface of the steel sheet, and the arc spreads too much, resulting in a wide penetration width. The back bead width is too large. Therefore, the wire diameter of the first electrode is set to 4.0 to 4.8 mm. As described above, the first electrode in the high-speed current single-sided welding of the first electrode, as described above, flows a high current to enhance the concentration of the arc, digs down to the back surface of the steel plate to open a stable keyhole, and secures the amount of deposition. The current is 1200
If the current is less than A, the arc force for digging to the back surface of the steel sheet cannot be obtained, and the amount of welding is insufficient. On the other hand, if a current exceeding 1700 A is used, the proper operating current range with respect to the wire diameter is far exceeded, the melting rate of the wire becomes unstable, and the digging force due to the arc becomes too strong. The arc may fly directly to the copper plate and damage it. Therefore, the current of the first electrode is 120
0 to 1700A. Voltage of the first electrode If the voltage of the first electrode is less than 30 V, a high current is used, so voltage control is difficult, and the penetration into the back side of the steel sheet becomes too deep, and the back bead is likely to be convex. vice versa,
When the voltage exceeds 40V, the arc spreads, the penetration to the back side becomes shallow, and the extra height of the back bead becomes insufficient,
Also, the bead width becomes unstable. Therefore, the voltage of the first electrode is set to 30-40V. Arc when the first electrode moves from the vertical end to the tab plate
Fluctuation amount at the point of occurrence A tab plate is attached to the end of the joint so as to contact it, but the difference in height between the groove bottom of this joint end and the upper surface of the arc passage portion of the tab plate Is 16m
If it is more than m, the arc length changes suddenly and the arc length cannot be controlled. Short-circuiting occurs or the arc point changes suddenly even before the short-circuiting occurs, resulting in discontinuity in the meltdown and the end of the joint. Cracks occur in the weld line direction of the weld metal.

FIG. 1 shows a tab plate 2 arranged so as to come into contact with a joint end portion of a welded material 1, and a height between a groove bottom portion 3 of the welded material 1 and an upper surface of the tab plate 2 is shown. Difference A of 16mm
Is less than. However, there is no restriction on the plate thickness of the entire tab plate. For example, as shown in FIG. 2, a thick plate (restraining plate 5) is used for the part that restrains the joint end portion (prevents cracking at the end), and therefore a thick plate (constraint plate 5) is used. What has a thickness (tab plate 4) may be used. 2, (a) is a front view, (b) is a plan view,
(C) is a longitudinal sectional view. The tab plate 4 is thinner than the tab plate 2, and the tab plate 4 is constrained by a thick constraining plate 5. The height difference A between the upper surface of the tab plate 4 to be terminated and the groove bottom 3 may be set to less than 16 mm.

Even if the tab plate as a whole has a plate thickness outside the above range, as shown in FIG. 3, the groove is such that only the portion which is in contact with the joint end portion and through which the arc passes is within the above range. 7
May be provided. The tab plate 5 is formed with two slits 6 so as to sandwich the extended portion of the groove. Also in FIG. 3, (a) is a front view, (b) is a plan view,
(C) is a longitudinal sectional view.

Further, as shown in FIG. 4, the tab plate 5 may be provided with an inclined surface 8. In any case, when the arc is transferred from the welded material 1 to the tab plate 5, the height difference A between the groove bottom of the welded material 1 and the upper surface of the arc passage portion of the tab plate 5 is 16 mm. It should be less than. As a result, the sudden change in the arc generation point is less than 16 mm,
It is possible to control the arc length and prevent short circuits. As is clear from the above description, the present invention is effective when the material 1 to be welded has a plate thickness of 16 mm or more. Others The present invention is, as described above, for solving the problem that occurs when the electrode moves from the joint end portion of the most preceding first electrode to the tab plate during high-speed single-sided submerged arc welding, There are no particular restrictions on the welding conditions for other electrodes, that is, the distance between electrodes, the electrode diameter, the inclination, and the like, and the welding material.

[0012]

EXAMPLES Next, examples of the present invention will be described in comparison with comparative examples.

Welding tests were carried out using the steel plates shown in Table 1 below, the wires shown in Table 2 and the flux shown in Table 3 under the groove shapes and welding conditions shown in Table 4. The welding method was a one-sided welding method using a flux and a copper plate as the backing. Table 5 shows the plate thickness of the material to be welded, the first electrode diameter, the welding speed and the thickness of the tab plate. Table 6 shows the welding quality such as the condition of the joint portion of the tab plate, the A distance, the condition of the back bead, and the defect of the joint end portion.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3]

However, the other components are CO ₂ , B ₂ O ₃ ,
Fe-Si, Fe-Mn and the like.

[0018]

[Table 4]

[0019]

[Table 5]

[0020]

[Table 6]

As is clear from Table 6, the test symbols 1 to 7 satisfying all the requirements of the present invention did not cause defects at the joint end portions, and sound welded joints were obtained. On the other hand, in test symbol 8, the wire diameter of the first electrode was small, and high current could not be used, so that the back bead was insufficient in size and was unstable. In test symbol 9, the welding current was high and the voltage was too high, so both the back bead surplus and width were excessive. Since the wire diameter of test symbol 10 was too large, the excess height of the back bead was unstable and the width was excessive. Although the test bead 11 had a good back bead, although the arc was short-circuited once when the first electrode moved from the joint end portion to the tab plate, the arc was generated again at the tab plate and the welding was completed, A crater remained at the end of the joint and a crater crack occurred in that portion. The test symbol 12 also showed the same phenomenon as the test symbol 11, and a similar defect occurred. In test symbol 13, when the first electrode moved to the tab plate, the arc was short-circuited to the tab plate, re-arc did not occur, and the welding was stopped. Test symbol 14 was welded at a low welding speed of 80 cm / min. No arc short circuit phenomenon was observed when the first electrode moved from the joint end portion to the tab plate. was gotten.

[0022]

As described above, according to the present invention,
In high-speed one-sided submerged arc welding with a welding speed of 90 cm / min or more, a sound welded portion can be obtained up to the end of the joint, and a highly efficient one-sided submerged arc welding method can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view illustrating a height difference A between a groove bottom portion and a tab plate upper surface of the present invention.

FIG. 2 is a diagram of the case where the tab plate is thin and a constraining plate is used.

FIG. 3 is a diagram when a groove is formed in the tab plate.

FIG. 4 is a diagram showing a case where an inclined surface is formed on the tab plate.

[Explanation of symbols]

 1: material to be welded 2, 4, 5: tab plate 3: groove bottom part 6: slit 7: groove 8: inclined surface

Claims (1)

[Claims] 1. In the method of single-sided submerged arc welding with multiple electrodes, the most advanced welding conditions for the first electrode are as follows: electrode diameter: 4.0-4.8 mm, current: 1200-1700.
A, voltage: 30 to 40 V, welding speed: 90 cm / min or more, and an end plate attached to the end of the joint is arranged so that the groove bottom provided on the material to be welded and the end plate are in contact with each other. A single-sided submerged arc welding method, wherein the height from the groove bottom of the material to be welded to the upper surface of the end plate at the boundary with the end plate is less than 16 mm.