JP2019013954A - Method for repairing welding defect part - Google Patents

Abstract

To provide a method for repairing welding defect part that allows drastic time saving for repair work.SOLUTION: When a defect is present in a weld part W, a method for repairing welding defect part includes radiating a laser beam LB to the weld part W, and melting a peripheral part of the defect of the weld part W to perform repair welding.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for repairing a weld defect.

  In a welded portion between welded members made of metal members, defects such as porosity, poor fusion, slag entrainment, poor penetration, and cracking may occur when the welding conditions are not appropriate. The presence of such defects is not preferable because it leads to a decrease in welding strength.

  Therefore, conventionally, when such a defect is found in the welded part, the part including the defect in the welded part is scraped off, and the welded part is further welded by arc welding or the like to repair the welded part. (Patent Document 1).

JP2012-240059A

  However, the conventional method for repairing a welded portion has a problem in that after the portion including the defect in the welded portion is scraped off, further welding must be performed, and the repair work takes time and much time.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a method for repairing a defect in a welded portion that can realize a significant time reduction in repair work.

  In order to achieve the above object, a repair method for a weld defect in the first aspect of the present invention is a repair method for a weld defect that repairs a defect present in a weld part of a welded member to be welded. The defect is a defect existing inside the welded portion, and a laser beam is applied to the welded portion, and the portion around the defect in the welded portion is melted for repair welding.

  As a repair method for a weld defect in the second aspect, laser arc hybrid welding is employed in which welding is performed between members to be welded by combining arc welding and laser welding, and the laser beam is welded while performing arc discharge. The portion is irradiated and the repair welding is performed.

According to a third aspect of the repair method for a weld defect, the repair welding is performed by swinging the laser beam in a width direction of the weld.
According to a fourth aspect of the present invention, there is provided a repair method for a weld defect, wherein the repair welding is performed by irradiating the weld while moving the laser beam on a weld line formed by the weld.

  According to a fifth aspect of the repair method of a defect in a welded portion, the laser beam is oscillated in a width direction of the welded portion, and the laser beam is irradiated on the welded portion while being moved on a weld line formed by the welded portion. Then, the repair welding is performed, the scanning speed obtained by combining the rocking speed and the moving speed is 2.5 m / min or less, and the moving distance in the rocking cycle is 2.8 mm or less.

According to the defect repairing method of the present invention, when there is a defect inside the welded portion, the portion around the defect is irradiated with a laser beam, so that the portion around the defect is melted and a molten pool is formed again. The defects are taken into the molten pool and disappear.
Thereby, it is possible to repair the weld defect with a simple configuration in which a laser beam is irradiated to a portion around the defect, and the time for repair work can be greatly shortened.

It is a figure which shows a laser arc hybrid welding apparatus. It is a figure which shows the defect inside a welding part. It is a photograph which shows the welding part which performed repair welding. It is a figure which shows the area | region which can repair the defect inside a welding part as an experimental result. It is a figure which shows typically the relationship between the distance along a welding line, and a rocking | fluctuation width regarding a laser beam. It is a figure which shows the experimental result at the time of carrying out repair of a welding part by changing the oscillation width and oscillation frequency of a laser beam variously, varying laser scanning speed. It is a figure which shows the weld part of the fillet weld which has a defect which consists of a penetration defect inside. It is a figure which shows the weld part of the fillet weld which performed repair welding.

Hereinafter, a method for repairing a weld defect according to the present invention will be described with reference to the drawings.
In the method of repairing a weld defect according to the present invention, for example, a laser arc hybrid welding technique is used in which welding is performed between welded members that are metal members by performing arc welding and laser welding together. .

  Referring to FIG. 1, a laser arc hybrid welding apparatus for performing laser arc hybrid welding is shown in a state where repair work is performed on a welded portion W of the welded members S and S which are butt welded. An outline of the welding apparatus will be described.

  The laser arc hybrid welding apparatus 1 includes an arc welding apparatus 10 and a laser welding apparatus 20, and the welding direction of the members to be welded S, S, that is, the direction along the continuous weld line of the welded portion W (indicated by arrows in the figure). It is configured to be movable.

  The arc welding apparatus 10 is configured such that, for example, a welding wire 14 as a consumable electrode is sent obliquely from the tip of a welding torch 12 to the welded portion W of the members to be welded S, S. In addition, the arc welding apparatus 10 may be configured to attach an electrode rod that does not wear to the tip of the welding torch 12, so that only arc discharge can be performed.

On the other hand, the laser welding apparatus 20 is configured to focus a laser beam LB supplied from a laser generator (not shown) by a laser irradiation head 22 and irradiate the welded portions W of the members to be welded S and S. . In addition, the laser welding apparatus 20 is configured so that the laser beam LB collected through the laser irradiation head 22 is perpendicular to the welding line of the members to be welded S, that is, the width direction of the welded portion W (indicated by arrows in the drawing). It is also configured to be swingable. As the type of laser, a YAG laser, a CO ₂ laser, a fiber laser, a disk laser or the like is employed.

  In the laser arc hybrid welding apparatus 1 configured as described above, the members to be welded S and S are set so that the welding line coincides with the line connecting the tip of the welding wire 14 and the condensing point of the laser beam LB, and welding is performed. The welding operation is performed in the order of arc welding and laser welding in the direction along the line (in the direction of the arrow in the figure).

Hereinafter, a method for repairing a weld defect according to the present invention will be described in detail.
Nondestructive inspection and the like are performed on the welded parts W of the welded members S and S constituting the welded structure, and the porosity, fusion failure, slag entrainment, poor penetration as shown in FIG. When a defect such as a crack is discovered, the laser arc hybrid welding apparatus 1 is used to focus the laser beam LB on the tip of the welding wire 14 and the laser beam LB in order to perform arc discharge and laser irradiation on the defective portion. Set to match the line connecting the points.

Hereinafter, the repair method according to the state of a defect is demonstrated as Example 1- Example 3. FIG.
[Example 1]
In the first embodiment, a case where only one defect exists inside the welded portion W of the welded members S and S that have been butt welded will be described.
In this case, since only one defect need be repaired, the repair work is performed without greatly moving the arc welding apparatus 10 and the laser welding apparatus 20.

  First, the arc welding apparatus 10 is operated, and arc discharge is performed from the welding wire 14 toward the defect. Thereby, the peripheral part of the defect of the welding part W fuse | melts. At this time, it is not necessary to completely melt the weld W by arc discharge, and the arc current is appropriately adjusted so as to melt the weld W to some extent.

  And when the peripheral part of the defect of the welding part W will be in the state melted to some extent, the laser welding apparatus 20 will be operated and laser irradiation will be performed toward a defect. Specifically, the arc welding apparatus 10 and the laser welding apparatus 20 are moved together so that the irradiation position of the laser beam LB condensed by the laser irradiation head 22 becomes a position corresponding to the defect, and laser in normal laser welding is performed. Laser irradiation with power.

  Further, the laser beam LB focused and irradiated by the laser irradiation head 22 is swung in a direction perpendicular to the welding line, that is, in the width direction of the welded portion W. Here, for example, the laser beam LB is swung so as to reciprocate the laser irradiation head 22 at a constant cycle.

  As described above, when the laser beam LB is condensed and irradiated toward the defect while the peripheral portion of the defect is melted to some extent by the arc discharge, the laser beam LB reaches a portion deeper than the arc discharge. The peripheral part of the defect of the melted weld W is almost completely melted, and a molten pool is formed again.

  Thereby, even if the defect existing in the welded portion W exists in a deep position of the welded portion W, the molten pool newly formed by the arc discharge and the laser beam LB. It is taken in and disappears.

  In particular, by swinging the laser beam LB in the width direction of the welded portion W, not only the welded portion W but also the members to be welded S and S around the welded portion W are partially melted, and the range of the molten pool Is wider than the range of the original weld W. As a result, the defects are easily taken into the molten pool, and even if the defects are relatively large, they disappear well.

  For example, when the defect is porosity, the porosity is filled with the weld metal of the molten pool, or the molten pool is stirred by the oscillation of the laser beam LB so that the gas in the porosity is transferred from the molten pool to the atmosphere. Dissipates and disappears.

  Furthermore, by newly oscillating the laser beam LB, it is possible to prevent a new defect from occurring. For example, when a defect exists in a relatively deep position of the weld W, it is usually necessary to increase the output of the laser beam LB. If the output of the laser beam LB is high as described above, a new crack or the like is required. However, by oscillating the laser beam LB, the range of the molten pool is expanded and the molten pool is agitated, and is taken into the molten pool from the side where the new defect is generated. Generation of defects is prevented beforehand.

  Referring to FIG. 3, a repair result obtained by performing repair welding by performing arc discharge on a defect inside the weld W and irradiating the laser beam LB while swinging is shown as a new weld W ′. However, as shown in the photograph, the defect disappears well.

  Here, the laser beam LB is oscillated, but the laser beam LB may not be oscillated when the defect exists at a relatively shallow position of the welded portion W. If the laser beam LB is not oscillated, the penetration tip width is narrow and the range of the molten pool is also narrowed. However, if the defect is a relatively shallow position of the weld W, the defect is taken into the molten pool and extinguished. Is possible.

  Referring to FIG. 4, the region in the welded portion W where the defect can be repaired is a case where the laser beam LB is not oscillated (marked by ♦) and a case where the laser beam LB is oscillated with a predetermined oscillation width (for example, a width of 6 mm) The results are shown as experimental results. As shown in the figure, when the laser beam LB is not oscillated, the width of the penetration tip of the laser beam LB is narrow, so that it is difficult to repair defects at a deep position of the weld W, but the weld W A defect at a relatively shallow position can be repaired. On the other hand, if the laser beam LB is swung, not only a relatively shallow position of the welded portion W but also a relatively deep position of the welded portion W (for example, a depth of 20 mm) and the vicinity of the widthwise outer edge of the welded portion W. It is possible to sufficiently repair defects in the area.

  Further, here, laser discharge is performed by the laser welding apparatus 20 after arc discharge is performed by the arc welding apparatus 10 toward the defect, but the laser welding apparatus 20 is not performed by the arc welding apparatus 10 without performing arc discharge. Only laser irradiation may be performed. Even in this case, for example, when the defect is relatively small, it is possible to sufficiently melt the portion around the defect of the welded portion W to form a molten pool.

  In the arc welding apparatus 10, when the welding wire 14 is used as a consumable electrode, the welding wire 14 is eluted as a filler material to form a new weld metal. When the electrode rod that is not used is used, only arc discharge is performed, and consumption of the welding wire 14 is suppressed.

[Example 2]
In the second embodiment, a case where a plurality of defects exist continuously along the weld line in the welded portion W of the welded members S and S that have been butt welded will be described as an example.
In this case, the arc welding apparatus 10 is operated to start arc discharge from the welding wire 14 in the range of the weld W where the defect exists, and then the arc welding apparatus 10 and the laser welding apparatus 20 are moved along the welding line. Then, the laser welding apparatus 20 is also operated and laser irradiation is continuously performed toward the welded portion W.

  At this time, while moving the arc welding apparatus 10 and the laser welding apparatus 20 along the welding line, the laser beam LB condensed and irradiated by the laser irradiation head 22 is perpendicular to the welding line, that is, at the welding part W. Swing in the width direction.

That is, as schematically shown in FIG. 5 as the relationship between the distance along the weld line and the rocking width, the laser beam LB is moved along the weld line and simultaneously swung in the width direction of the welded portion W to perform scanning. Let
When the scanning is repeatedly performed while moving the laser beam LB as described above, the center of the laser beam LB is the same, unlike the case where the scanning is performed without moving as in the case of the first embodiment. Do not pass again on the trajectory. Therefore, in order to sufficiently melt the weld W to form the molten pool, the oscillation speed and movement speed of the laser beam LB, that is, the laser scanning speed obtained by combining these, and the degree of overlap of the laser beams LB are correlated. The moving distance (hereinafter referred to as the pitch) in the oscillation cycle of the laser beam LB is an important factor.

  Specifically, the laser scanning speed and pitch are set so that the laser scanning speed is 2.5 m / min or less and the pitch is 2.8 mm or less as shown in FIG. 5, and the laser beam LB is scanned. .

Referring to FIG. 6, experimental results are shown in the case where the welded portion W is repaired by changing the oscillation width and oscillation frequency in various ways and varying the laser scanning speed. In this figure, the horizontal axis indicates the laser scanning speed, and the vertical axis indicates the penetration depth / penetration tip width (value obtained by dividing the penetration depth by the penetration tip width). Here, as welding conditions, the arc current was 100 A, 125 A, or 150 A, the laser power was 10 kW or 15 kW, and CO ₂ (flow rate 20 L / min) was used as the shielding gas.

  For example, when the oscillation frequency is small, the laser scanning speed is small but the pitch is large and the penetration depth / penetration tip width is large. Tend to be.

In FIG. 6, a circle mark corresponds to a case where the laser scanning speed exceeds 2.5 m / min, or a case where the pitch exceeds 2.8 mm. When the penetration depth / penetration tip width is 3 or more in the vicinity of 1.2 m / min, the pitch exceeds 2.9 mm, 3.6 mm, 4.9 mm and 2.8 mm, respectively. At one point where the laser scanning speed is near 2.7 m / min and the penetration depth / penetration tip width is near value 1, the laser scanning speed exceeds 2.5 m / min and the pitch is 4.4 mm. It is over 8mm. In these cases, as shown in the corresponding photographs (a) and (c), the defect has not disappeared or a new defect is generated, which is inappropriate for repair welding.
On the other hand, in FIG. 6, the mark ● corresponds to the case where the laser scanning speed is 2.5 m / min or less and the pitch is 2.8 mm or less. In this case, as shown in the corresponding photograph (b) The defect has disappeared or no new defect has occurred, and repair welding is appropriate.

  In this way, by setting the laser scanning speed and the pitch so that the laser scanning speed is 2.5 m / min or less and the pitch is 2.8 mm or less, the defect is repaired while the laser beam LB is appropriately scanned. Even when there are a plurality of defects continuously along the weld line inside the weld W, high-quality repair welding can be realized.

  In particular, as shown in FIG. 4 in the first embodiment, there is a defect in a region where the defect inside the welded portion W can be repaired, and the oscillation of the laser beam LB is changed to a predetermined oscillation width (for example, In the case where the width is 6 mm, high-quality repair welding can be realized by one-pass repair welding. Even when the defect exists over a wide range beyond the repairable region, high-quality repair welding can be realized in the same manner by performing repair welding in a multi-pass manner.

  The laser welding apparatus 20 may perform only laser irradiation without performing arc discharge with the arc welding apparatus 10, and the point that an electrode rod that does not wear out may be used in place of the welding wire 14 is the first embodiment. It is the same as the case of.

[Example 3]
In the third embodiment, a case where there is a defect due to poor penetration inside the pair of welded portions W of the fillet welded members S and S will be described as an example. The welded portion W includes a portion that should be originally welded.

  In fillet welding, as shown in FIG. 7, there is a defect consisting of a penetration defect such that the members to be welded S, S remain unwelded inside the welded part W, and such a defect Even so, it is possible to repair using the laser arc hybrid welding apparatus 1.

  That is, in one or both of the pair of welded portions W, the arc welding device 10 is operated to perform arc discharge in the same manner as described in the first and second embodiments, and the laser welding device 20 directs the welded portion W toward the welded portion W. Laser irradiation.

  Thereby, as shown in FIG. 8, a weld pool is newly formed in the portion where the welded members S and S have poor penetration, and the welded members S and S are good without any further defects. Are welded to each other to eliminate the penetration failure, and a new welded portion W ′ is formed.

  As described above, according to the weld defect repair method according to the present invention, when defects such as porosity, poor fusion, slag entrainment, poor penetration, cracks, etc. are found inside the weld W, the defect By condensing and irradiating at least the laser beam LB on the surrounding portion, the portion around the defect can be melted to form a molten pool again, and the defect can be satisfactorily eliminated while the defect is taken into the molten pool. . As a result, it is possible to improve the defect existing inside the welded portion W with a simple configuration of irradiating the laser beam LB around the defect, and to greatly repair the welded portion W. It can be shortened.

  In this case, the laser arc hybrid welding technique is applied, and the laser beam LB is condensed and irradiated to the weld W while performing arc discharge, so that the weld W includes the peripheral portion of the defect by arc discharge. The laser beam LB can be irradiated in a state of being melted to a certain extent, and the peripheral portion of the defect can be melted almost completely to form a molten pool, and sufficient repair welding can be performed.

  Further, by causing the focused laser beam LB to oscillate in the width direction of the welded portion W, the range of the molten pool can be expanded more than the range of the original welded portion W, and defects can be easily taken into the molten pool. Even when the defects are relatively large, they can be eliminated well, and the occurrence of new defects can be prevented by stirring the molten pool.

  Further, the laser beam LB is oscillated in the width direction of the welded portion W and irradiated on the welded portion W while being moved on the weld line formed by the welded portion W. The scanning speed at this time is 2.5 m / min. By setting the pitch to 2.8 mm or less, it is possible to prevent the occurrence of new defects in the case where a plurality of defects are continuously present along the weld line in the welded portion W. High quality repair welding can be realized.

Although the description of the embodiment according to the present invention is finished above, the embodiment is not limited to the above, and various modifications can be made without departing from the spirit of the invention.
For example, in the above-described embodiment, the laser arc hybrid welding technique is applied and the repair welding of the welded portion W is performed using the laser arc hybrid welding apparatus 1, but repair welding is performed only by laser irradiation without performing arc discharge. When performing this, a laser welding apparatus may be used instead of the laser arc hybrid welding apparatus 1.

  Moreover, in the said embodiment, although the welding part W in the butt welding of the to-be-welded members S and S or the repair of the defect which exists in the inside of the welding part W in fillet welding was demonstrated as an example, If a defect exists, the repair method for a weld defect according to the present invention is applicable.

DESCRIPTION OF SYMBOLS 1 Laser arc hybrid welding apparatus 10 Arc welding apparatus 12 Welding torch 14 Welding wire 20 Laser welding apparatus 22 Laser irradiation head LB Laser beam S To-be-welded member W, W 'welding part

Claims (5)

A method for repairing a defect in a welded part for repairing a defect present in a welded part of a welded member to be welded,
The defect is a defect present inside the weld,
A method for repairing a defect in a welded part, wherein the welded part is irradiated with a laser beam, and a portion around the defect in the welded part is melted for repair welding.   Laser arc hybrid welding in which arc welding and laser welding are combined to weld the welded members together is adopted, and the laser beam is irradiated to the welded part while performing arc discharge, and the repair welding is performed. The repair method of the weld part defect of 1 description.   The method for repairing a weld defect according to claim 1 or 2, wherein the repair welding is performed by swinging the laser beam in a width direction of the weld.   The method for repairing a weld defect according to any one of claims 1 to 3, wherein the repair welding is performed by irradiating the weld while moving the laser beam on a weld line formed by the weld. . The repair welding is performed by irradiating the weld while moving the laser beam on a weld line formed by the weld,
The method for repairing a weld defect according to claim 3, wherein the scanning speed obtained by combining the rocking speed and the moving speed is 2.5 m / min or less, and the moving distance in the rocking cycle is 2.8 mm or less.