JP7189516B2 - Weld defect repair method - Google Patents

Description

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

Defects such as porosity, poor fusion, slag entrainment, poor penetration, and cracks may occur in the welded portion between members to be welded, which are made of metal members, when the welding conditions are not appropriate. The existence of such defects leads to a decrease in welding strength, which is not preferable.

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

JP 2012-240059 A

However, in the conventional method for repairing the welded portion, welding must be performed after scraping off the defective portion of the welded portion.

SUMMARY OF THE INVENTION 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 defects in a weld zone, which can significantly shorten the time required for repair work.

In order to achieve the above object, a method for repairing a defect in a weld zone according to a first aspect of the present invention is a method for repairing a defect existing in a weld zone of a welded member that has been welded, the method comprising: A defect is a defect existing inside the welded portion, and the welded portion is irradiated with a laser beam to melt a portion of the welded portion around the defect to perform repair welding, thereby performing arc welding and laser welding. At the same time, laser arc hybrid welding for welding and joining the welded members is adopted, and the laser beam is focused and irradiated toward the defect while the welded portion is melted by arc discharge. The repair welding is performed by swinging in the width direction.

A method for repairing a defect in a welded portion according to a second aspect is characterized in that the laser beam is irradiated to the welded portion while being moved on a weld line formed by the welded portion to perform the repair welding.

A method for repairing a defect in a weld zone according to a third aspect includes irradiating the weld zone while oscillating the laser beam in the width direction of the weld zone and moving the laser beam on the weld line formed by the weld zone. 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 method for repairing weld defects of the present invention, when a defect exists inside the weld, laser arc hybrid welding is employed in which the members to be welded are welded together by combining arc welding and laser welding. In the state in which the weld is melted by arc discharge, a laser beam is condensed toward the defect and radiated, and the repair welding is performed by swinging the weld in the width direction. It melts and forms a molten pool again, and the defect is taken into the molten pool and disappears.
As a result, it is possible to repair the defect of the weld with a simple configuration in which the laser beam is irradiated to the part around the defect while the weld is melted by arc discharge while swinging in the width direction of the weld. Work time can be greatly reduced.

It is a figure which shows a laser arc hybrid welding apparatus. FIG. 10 illustrates a defect inside a weld; It is a photograph which shows the welded part which performed repair welding. FIG. 10 is a diagram showing experimental results of repairable regions of defects inside the welded portion; FIG. 5 is a diagram schematically showing the relationship between the distance along the weld line and the oscillation width of the laser beam. FIG. 10 is a diagram showing experimental results when repairing a welded portion by varying the oscillation width and oscillation frequency of a laser beam and varying the laser scanning speed. FIG. 3 shows a weld of a fillet weld with a defect consisting of poor penetration therein. It is a figure which shows the welded 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 for repairing defects in welded portions according to the present invention, for example, laser arc hybrid welding technology for welding and joining members to be welded, which are metal members, by performing arc welding and laser welding together is applied. .

Referring to FIG. 1, a laser arc hybrid welding apparatus for performing laser arc hybrid welding is shown in a state of repairing a welded portion W of butt welded members S, S, and will be hereinafter referred to as a laser arc hybrid. An outline of the welding device will be described.

The laser arc hybrid welding device 1 is composed of an arc welding device 10 and a laser welding device 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 the arrow in the figure) is configured to be movable to

The arc welding apparatus 10 is configured such that a welding wire 14 as a consumable electrode is sent obliquely from the tip of a welding torch 12, for example, to a welding portion W of the members S, S to be welded. In the arc welding apparatus 10, a non-consumable electrode rod may be attached to the tip of the welding torch 12, so that only arc discharge can be performed.

On the other hand, the laser welding device 20 is configured to converge a laser beam LB supplied from a laser generator (not shown) with a laser irradiation head 22 and irradiate the welding portion W of the members S, S to be welded. . In addition, the laser welding device 20 emits a laser beam LB condensed through a laser irradiation head 22 in a direction perpendicular to the welding line of the members S to be welded, that is, in the width direction of the welded portion W (indicated by an arrow in the figure). It is also configured to be swingable. YAG lasers, _CO2 lasers, fiber lasers, disk lasers, etc. are employed as the types of lasers.

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

Hereinafter, a method for repairing defects in welded portions according to the present invention will be described in detail.
A nondestructive inspection or the like is performed on the welded portion W of the welded members S, S constituting the welded structure, and porosity, poor fusion, slag entrainment, poor penetration, as shown in FIG. When a defect such as a crack is found, the laser arc hybrid welding apparatus 1 is used to connect the welding line of the welded portion W to the tip of the welding wire 14 and the focus of 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, repair methods according to the state of the defect will be described as Examples 1 to 3.
[Example 1]
In the first embodiment, a case in which only one defect exists inside the welded portion W of the members to be welded S, S that are butt-welded will be described as an example.
In this case, since only one defect needs to be repaired, the repair work is performed without moving the arc welding device 10 and the laser welding device 20 significantly.

First, the arc welding apparatus 10 is operated and arc discharge is performed from the welding wire 14 toward the defect. As a result, the peripheral portion of the defect in the welded portion W is melted. At this time, it is not necessary to completely melt the welded portion W by arc discharge, and the arc current is appropriately adjusted so as to melt the welded portion W to some extent.

Then, when the peripheral portion of the defect of the welded portion W is melted to some extent, the laser welding device 20 is operated to irradiate the defect with a laser beam. Specifically, the arc welding device 10 and the laser welding device 20 are moved together so that the irradiation position of the laser beam LB condensed by the laser irradiation head 22 corresponds to the defect, and the laser beam in normal laser welding is moved. Laser irradiation is performed with power.

Further, the laser beam LB condensed and irradiated by the laser irradiation head 22 is oscillated in the direction perpendicular to the weld line, that is, in the width direction of the welded portion W. Here, for example, the laser beam LB is oscillated by reciprocating the laser irradiation head 22 at a constant cycle.

In this way, when the laser beam LB is condensed and irradiated toward the defect in a state where the peripheral portion of the defect is melted by the arc discharge to some extent, the laser beam LB reaches a deeper portion than the arc discharge. The peripheral portion of the melted weld W defect is almost completely melted, and a molten pool is formed again.

As a result, even if the defect existing inside the welded part W exists at a deep position in the welded part W, a new molten pool is formed by the arc discharge and the laser beam LB. absorbed into and disappear.

In particular, by oscillating the laser beam LB in the width direction of the welded portion W, not only the portion of the welded portion W but also the members to be welded S, S around the welded portion W are partially melted, and the range of the molten pool is melted. is wider than the original weld zone W. This makes it easier for the defects to be incorporated into the weld pool, and even if the defects are relatively large, they disappear favorably.

For example, when the defect is porosity, the porosity is filled with the weld metal of the molten pool, or the gas in the porosity is released from the molten pool into the atmosphere by agitating the molten pool by the oscillation of the laser beam LB. Dissipate and disappear.

Furthermore, by oscillating the laser beam LB, it is possible to prevent new defects from occurring. For example, if the defect exists at a relatively deep position in the weld W, it is usually necessary to increase the output of the laser beam LB. However, by oscillating the laser beam LB, the range of the molten pool is expanded and the molten pool is agitated. Defect generation is obviated.

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

Although the laser beam LB is oscillated here, the laser beam LB does not need to be oscillated if the defect exists at a relatively shallow position in 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 narrow. is possible.

Referring to FIG. 4, the defect repairable region inside the welded portion W is shown when the laser beam LB is not oscillated (marked with ♦) and when it is oscillated with a predetermined oscillation width (for example, width 6 mm) ( ) and ) are shown as experimental results. As shown in the figure, when the laser beam LB is not oscillated, the penetration tip width of the laser beam LB is narrow. It is possible to repair defects in relatively shallow positions. On the other hand, if the laser beam LB is made to oscillate, not only a relatively shallow position of the welded portion W but also a relatively deep position (for example, 20 mm deep) of the welded portion W and the vicinity of the widthwise outer edge of the welded portion W can be detected. It is possible to sufficiently repair defects in

Further, here, the laser irradiation is performed by the laser welding device 20 after the arc discharge is performed by the arc welding device 10 toward the defect. Only laser irradiation may be performed by . Even in this case, for example, when the defect is relatively small, it is possible to sufficiently melt the portion of the weld W around the defect to form a molten pool.

Further, when the welding wire 14 is used as the consumable electrode in the arc welding apparatus 10, the welding wire 14 is eluted as a filler material to form a new weld metal. If an electrode rod that does not have arc discharge is used, the consumption of welding wire 14 can be suppressed.

[Example 2]
In the second embodiment, a case in which a plurality of defects continuously exist along the weld line inside the welded portion W of the butt-welded members S, S will be described as an example.
In this case, after the arc welding device 10 is operated to start arc discharge from the welding wire 14 in the range of the weld W where the defect exists, the arc welding device 10 and the laser welding device 20 are moved along the weld line. The laser welding device 20 is also operated to continuously irradiate the welded portion W with the laser beam while the laser welding device 20 is being moved.

At this time, while moving the arc welding device 10 and the laser welding device 20 along the weld line, the laser beam LB condensed and irradiated by the laser irradiation head 22 is directed perpendicularly to the weld line, that is, the welded portion W. Swing in the width direction.

That is, as schematically shown in FIG. 5, the relationship between the distance along the weld line and the oscillation width is obtained by moving the laser beam LB along the weld line and simultaneously oscillating it in the width direction of the welded portion W, thereby scanning the laser beam LB. Let
In the case where the laser beam LB is moved and repeatedly swung for scanning, the center of the laser beam LB is the same, unlike the situation where the laser beam LB is swung without being moved as in the case of the first embodiment. Do not pass over the trajectory again. Therefore, in order to sufficiently melt the welded portion W to form a molten pool, the oscillation speed and the moving speed of the laser beam LB, that is, the laser scanning speed obtained by combining these, and the degree of overlap of the laser beam LB and the correlation The movement distance (hereinafter referred to as pitch) of the laser beam LB in a certain oscillation cycle is an important factor.

Here, 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 of repairing the welded portion W by varying the oscillation width and oscillation frequency and varying the laser scanning speed. In the 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 either 100 A, 125 A or 150 A, the laser power was either 10 kW or 15 kW, and CO ₂ (flow rate 20 L/min) was used as the shielding gas.

Assuming that the moving speed of the laser beam LB is a predetermined moving speed that is commonly used, for example, when the oscillation frequency is small, the laser scanning speed is low, but the pitch is large, and the penetration depth/penetration tip width is large. tend to become

In FIG. 6, the ◯ mark corresponds to the case where the laser scanning speed exceeds 2.5 m/min or the case where the pitch exceeds 2.8 mm. At three points where the penetration depth/penetration tip width is 3 or more in the vicinity of 1.2 m/min, the pitches exceed 2.9 mm, 3.6 mm, 4.9 mm and 2.8 mm, respectively. At one point where the laser scanning speed is around 2.7 m/min and the penetration depth/penetration tip width is around 1, the laser scanning speed exceeds 2.5 m/min and the pitch is 4.4 mm. over 8 mm. In these cases, as shown in the corresponding photographs (a) and (c), the defects are not eliminated or new defects are 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. , the defect has disappeared or no new defect has occurred, and repair welding is appropriate.

Thus, 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, defects can be repaired while the laser beam LB is properly scanned. Even if a plurality of defects continuously exist inside the weld W along the weld line, high-quality repair welding can be realized.

In particular, as shown in FIG. 4 in the first embodiment, there is a defect in the region where the defect inside the welded portion W can be repaired, and the oscillation of the laser beam LB is set to a predetermined oscillation width (for example, , width 6 mm), high-quality repair welding can be achieved in one pass. Note that even if the defect exists in a wide range beyond the repairable region, repair welding of high quality can be similarly realized by performing repair welding in multiple passes.

Note that the laser welding device 20 may perform only laser irradiation without arc discharge by the arc welding device 10, and the welding wire 14 may be replaced by a non-consumable electrode rod, which is the first embodiment. is the same as for

[Example 3]
In the third embodiment, a case in which a defect due to insufficient penetration exists inside a pair of welded portions W of the members to be welded S, S that are fillet welded will be described as an example. In addition, the inside of the welded portion W also includes a portion to be welded.

In fillet welding, as shown in FIG. 7, there are defects due to poor penetration such that the members to be welded S, S are left unwelded inside the welded portion W, and such defects However, it can be repaired using the laser arc hybrid welding device 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 Examples 1 and 2, and the laser welding device 20 directs the arc toward the welded portion W. laser irradiation.

As a result, as shown in FIG. 8, a new molten pool is formed in the portion where the penetration between the members to be welded S and S was poor, and the members to be welded S and S are good without further defects. , the poor penetration is eliminated, and a new welded portion W' is formed.

As described above, according to the method for repairing defects of welded portions according to the present invention, when defects such as porosity, poor fusion, slag entrainment, poor penetration, and cracks are found inside the welded portion W, the defects By condensing and irradiating at least the laser beam LB to the surrounding portion, the portion around the defect can be melted and a molten pool can be formed again, and the defect can be favorably eliminated while incorporating the defect into the molten pool. . As a result, the defect present inside the welded portion W can be repaired satisfactorily with a simple configuration of irradiating the portion around the defect with the laser beam LB, and the repair work time of the welded portion W can be greatly reduced. can be shortened.

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

In addition, by oscillating the focused laser beam LB in the width direction of the welded portion W, the range of the molten pool is expanded from the original range of the welded portion W, and defects can be easily captured in the molten pool. Even if the defect is relatively large, it can be eliminated satisfactorily, and by stirring the molten pool, the occurrence of new defects can be prevented.

In addition, the laser beam LB is oscillated in the width direction of the welded portion W and irradiated to the welded portion W while being moved on the weld line formed by the welded portion W. At this time, the scanning speed is 2.5 m/min. By setting the pitch to 2.8 mm or less, in the case where multiple defects continuously exist along the weld line in the weld W, while preventing the occurrence of new defects. , 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 can be variously modified without departing from the gist of the invention.
For example, in the above-described embodiment, the technique of laser arc hybrid welding is applied and the laser arc hybrid welding apparatus 1 is used to perform repair welding of the welded portion W, but repair welding is performed only by laser irradiation without arc discharge. , a laser welding device may be used in place of the laser arc hybrid welding device 1 .

Further, in the above-described embodiment, repair of a defect existing inside the welded portion W in butt welding of the members S to be welded S, or in the welded portion W in fillet welding has been described as an example. If the defect exists, the method of repairing the weld defect according to the present invention can be applied.

1 laser arc hybrid welding device 10 arc welding device 12 welding torch 14 welding wire 20 laser welding device 22 laser irradiation head LB laser beam S member to be welded W, W' welded portion

Claims (3)

A weld defect repair method for repairing a defect existing in a weld of a welded member to be welded,
The defect is a defect existing inside the weld,
irradiating the welded portion with a laser beam to melt a portion of the welded portion around the defect to perform repair welding;
Adopting laser arc hybrid welding for welding and joining the members to be welded by combining arc welding and laser welding, the laser beam is focused toward the defect while the welded portion is melted by arc discharge. A method for repairing a defect in a welded portion, wherein the repair welding is performed by irradiating and swinging the welded portion in the width direction. 2. The method of repairing a defect in a weld zone according to claim 1, wherein said repair welding is performed by irradiating said laser beam to said weld zone while moving it on a weld line formed by said weld zone. The repair welding is performed by irradiating the weld while moving the laser beam on the weld line formed by the weld,
3. The method for repairing defects in welds according to claim 1 or 2, 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. .

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