JP6012326B2 - Electron beam welding method - Google Patents

Description

  The present invention relates to an electron beam welding method applied to an object to be welded.

  In general, an electron beam welder includes an electron gun, a vacuum chamber, an exhaust system, a workpiece driving device, a high voltage power source, a control panel, and the like. Electron beam welding is performed by irradiating an electron beam from an electron gun onto a butt portion formed by contacting two or more base materials (workpieces) that are in contact with each other, thereby rapidly melting and evaporating the butt portion. It is a welding method in which the two or more base materials are joined together.

Electron beam welding is generally known to be able to achieve high-quality welding because, for example, thermal deformation and welding distortion applied to the base material are small compared to conventional welding methods. Therefore, it is a very effective joining means for assembling workpieces (members) that require higher accuracy, and is widely applied from precision parts to large structural parts.
In particular, when applying electron beam welding to a relatively large structural part, the butt portion is different from a groove having a U-shaped cross section at the time of butt use normally used in submerged arc welding or TIG welding. It is considered as a type I groove. Therefore, it is possible to omit the labor associated with the groove processing, and welding itself is performed in one pass, and the number of man-hours can be greatly reduced as compared with the conventional case.

However, when it is performed in one pass, it is necessary to prevent welding defects due to misalignment with one weld bead, and the weld bead width must be wider than the groove width. Increasing the weld bead width not only increases heat input and causes a decrease in strength, but also decreases the cooling rate, so that an increase in strength due to the quenching effect cannot be obtained. As a result, the mechanical properties of the weld metal are deteriorated as a whole.
Further, in electron beam welding, since the weld bead is easily deflected by the fine magnetism in the steel sheet, a weld defect due to misalignment tends to occur as the thickness increases. In other words, as the plate thickness increases, the weld bead width needs to be increased in order to prevent misalignment, and the heat input also increases, so the mechanical properties of the weld metal tend to decrease as the plate thickness increases. is there.

Therefore, as a method of improving the mechanical properties of the weld metal while preventing misalignment by performing a plurality of passes instead of one pass, for example, techniques described in Patent Literature 1 and Patent Literature 2 are cited.
In the technique described in Patent Document 1, a plurality of passes are applied with a slight shift left and right from the groove. By welding the groove with a plurality of weld beads, a wide weld bead is formed, and joining without causing defects due to misalignment is performed. In the final pass, there is a method in which a thin weld bead with a small heat input is provided near the center in a wide range of weld beads and the strength is restored to the level of the base material by producing a quenching effect.

  In the technique described in Patent Document 2, after the first weld bead of the first pass is formed with a width wider than the groove, the second and third second and third passes after the second pass having a narrower width than the first weld bead. By forming the weld bead slightly shifted left and right from the groove, the total weld bead width is widened to prevent misalignment. Then, the second and third weld beads are shifted from the groove to form a small heat input to the first weld bead, and the first weld bead is remelted to refine crystal grains and improve toughness. There is.

JP-A-10-314960 JP 2012-35318 A

However, since both methods increase heat input, the cooling rate is slow and a sufficient quenching effect cannot be obtained, and the strength of the molten metal is reduced by heating a part of the base material below the melting point. It is difficult to obtain the strength of the weld metal due to problems such as being lower than the material.
Furthermore, in steel materials such as high-tensile steel using TMCP (Thermo-Mechanical Control Process), the strength of the weld metal is required more, but since the alloy elements are greatly reduced, sufficient weld metal strength is obtained. The problem is that it is even more difficult.
In addition, the conventional electron beam welding method requires changing the weld bead width every time each pass is applied, so it takes time and effort to adjust the conditions many times in order to weld a single groove. ing.

  The present invention has been made to solve the above-described problems, and provides an electron beam welding method that can easily prevent defects due to off-axis and prevent a decrease in the strength of the weld metal.

In order to solve the above problems, the present invention proposes the following means.
An electron beam welding method according to an aspect of the present invention includes a step of applying a primary weld bead so as to include a groove formed at a butt portion of two base materials, and a plurality of widths equal to the primary weld bead. the secondary weld bead, the overlapping primary weld bead, and includes a step of the plurality of secondary weld bead sequentially construction so as not to overlap each other, and the said secondary weld bead of the two base materials It is characterized in that the construction is carried out by inclining on the facing surface of the groove .

  According to such a structure, the width of the weld bead formed with respect to the groove can be increased by overlapping the primary weld bead and the secondary weld bead. Moreover, the heat input concerning a primary welding bead can be made small because a secondary welding bead does not mutually overlap. Furthermore, welding can be easily performed under the same welding conditions until the end by setting equal weld bead widths.

  According to such a configuration, since the region where the primary weld bead and the secondary weld bead overlap each other is reduced, the heat input to the primary weld bead can be further reduced.

  Furthermore, the electron beam welding method according to another aspect of the present invention is characterized in that a width of the primary welding bead and the secondary bead is set in a range of 1 mm to 3 mm.

  According to such a configuration, it is possible to reduce the heat input by forming the primary welding bead and the secondary welding bead with a narrow width, and the cooling rate of each welding bead is increased. By forming the weld bead with a narrow width, the width of the weld bead formed at the groove can be narrowed, and the formation of the weld bead larger than necessary than the width of the groove can be prevented.

  According to the electron beam welding method of the present invention, by overlapping the first weld bead and the second weld bead having the same width, the width of the weld bead formed with respect to the groove is widened to prevent a defect due to an off-axis. In addition, it is an object of the present invention to provide an electron beam welding method capable of easily reducing the heat input and preventing the strength of the weld metal from being lowered by not overlapping the second weld beads.

It is a longitudinal cross-sectional view explaining the process of the electron beam welding method which concerns on 1st embodiment of this invention. It is a longitudinal cross-sectional view explaining the process of the electron beam welding method which concerns on 2nd embodiment of this invention. It is a graph which shows the relationship of the intensity | strength of the Example and comparative example of this invention.

  Hereinafter, a first embodiment according to the present invention will be described with reference to FIG.

As shown in FIG. 1, in the electron beam welding method of the present embodiment, the secondary welding bead is formed twice after the first welding step S <b> 1 for forming the primary welding bead on the groove 5 of the base material 4. The second welding step S2 and the third welding step S3 are provided.
Specifically, in the electron beam welding method of the present embodiment, the preparation step S0 for forming the groove 5, the first welding step S1 for forming the first welding bead 1 as the primary welding bead, and the first two A second welding step S2 for forming a second welding bead 2 as a second welding bead, and a third welding step S3 for forming a third welding bead 3 as a second secondary welding bead. These steps are sequentially performed.

As shown in FIG. 1A, first, in the preparation step S0, the end surfaces of the two base materials 4 are butted together so as to form a groove 5 that is a butted portion. The position between the base materials 4 is adjusted so that the groove 5 has a width of 0 mm to 0.5 mm.
A material to which electron beam welding can be applied can be used for the work piece that is the base material 4. Among these, it is preferably used for high-strength steel using TMCP.

As shown in FIG. 1B, in the first welding step S <b> 1, the first weld bead 1 is formed in parallel to the groove 5 so as to include the groove 5. In order to set the width of the first weld bead 1 in the range of 1 mm to 3 mm, the welding conditions shown in Table 1 are used.
In addition, the width of the weld bead in this embodiment means the length of the narrowest part.

  Table 1 shows the electron beam welding conditions in this embodiment.

  As shown in FIG.1 (c), in 2nd welding process S2, after fully cooling the 1st welding bead 1 formed at 1st welding process S1, the 2nd welding bead which is a 1st secondary welding bead is shown. 2 is formed. In the second weld bead 2, the center line O 1 and the center line O 2 of the second weld bead 2 are vertically cut in contact with the first weld bead 1 at a biased position where the center line O 1 of the first weld bead 1 is not included. They are formed so as to be parallel to each other in a plan view, that is, in a cross-sectional view including the thickness direction of the base material 4. Here, in 2nd welding process S2, it constructs on the welding construction conditions of Table 1, and does not change welding construction conditions from 1st welding process S1.

As shown in FIG. 1 (d), in the third welding step S3, the second weld bead 2 is sufficiently cooled, and then the third weld bead 3 as the second secondary weld bead is formed. The third weld bead 3 is in contact with the first weld bead 1 at a biased position where the center line O1 of the first weld bead 1 on the opposite side to the second weld bead 2 is not included. The center line O3 of the weld bead 3 is formed to be parallel in a longitudinal sectional view. That is, since the third weld bead 3 does not contact the second weld bead 2, the third weld bead 3 is formed at a position that does not overlap. That is, the second weld bead 2 and the third weld bead 3 are formed with an interval so as to sandwich the groove 5. Here, in 3rd welding process S3, it constructs on the welding construction conditions of Table 1, and does not change welding construction conditions from 1st welding process S1.
The second weld bead 2 and the third weld bead 3 are preferably arranged symmetrically with respect to the center line O1 of the first weld bead 1, and are arranged symmetrically with respect to the groove 5 as a boundary. More preferably.

Next, the operation of the electron beam welding method configured as described above will be described.
According to the electron beam welding method as described above, the first weld bead 1, the second weld bead 2, and the third weld bead 3 overlap with each other so that the width of the first weld bead 1 formed on the groove 5 is increased. Can be made wider by the width of the second weld bead 2 and the third weld bead 3, and misalignment can be prevented. Furthermore, since the second weld bead 2 and the third weld bead 3 do not overlap each other, the central portion of the cooled first weld bead 1 is not heated twice or triple, thereby reducing heat input. It is possible to prevent a decrease in strength of the first weld bead 1 due to remelting. Furthermore, since it can weld on the same conditions to the last by setting it as equal weld bead width, welding can be easily applied with respect to the base material 4. FIG.

  Further, by forming the first weld bead 1 to the third weld bead 3 with a narrow width of 1 mm to 3 mm, the heat input of each weld bead can be reduced. Thereby, the cooling rate of each weld bead is increased, and the strength of the weld metal can be improved by the quenching effect. And the weld bead width finally formed with respect to the groove | channel 5 can be made narrow by forming the weld bead of a thin width | variety.

Next, the electron beam welding method of the second embodiment will be described with reference to FIG.
In the second embodiment, the same components as those in the first embodiment are given the same reference numerals, and detailed description thereof is omitted. The electron beam welding method of the second embodiment is different from the first embodiment in the second welding step S2 and the third welding step S3.

That is, in the second embodiment, the second inclined welding step S21 and the third oblique melting welding step S31 are performed while being inclined with respect to the first welding bead 1.
As shown in FIG.2 (c), in 2nd inclination welding process S21, after fully cooling the 1st welding bead 1 formed at 1st welding process S1, it is the 2nd inclination which is a 1st secondary welding bead. A weld bead 21 is formed. The second inclined weld bead 21 is in contact with the first weld bead 1 at a biased position where the center line O1 of the first weld bead 1 is not included. On the other hand, it forms so that the centerline O21 of the 2nd inclination welding bead 21 inclines. That is, the center line O21 of the second inclined weld bead 21 is inclined so as to approach the center line O1 of the first weld bead 1 in the direction of electron beam irradiation. Here, in 2nd inclination welding process S21, it constructs on the welding construction conditions of Table 1, and does not change a welding construction condition from 1st welding process S1.
As shown in FIG. 2D, in the third oblique welding step S31, the second inclined welding step S21 is sufficiently cooled, and then the third inclined weld bead 31 that is the second secondary welding bead is formed. . The third inclined weld bead 31 is in vertical sectional view while contacting the first weld bead 1 at a biased position not including the center line O1 of the first weld bead 1 on the opposite side to the second inclined welding step S21. The center line O31 of the third inclined weld bead 31 is formed to be inclined with respect to the center line O1 of the first weld bead 1. That is, the center line O31 of the third weld bead is inclined so as to approach the center line O1 of the first weld bead 1 as it goes in the electron beam irradiation direction. Here, in the third oblique melting welding step S31, the welding is performed under the welding conditions shown in Table 1, and the welding conditions are not changed from the first welding step S1.

  According to the electron beam welding method of the second embodiment as described above, the normal electron beam weld bead is formed slightly wider on the incident side, and the first weld bead 1, the second inclined weld bead 21, and the first Since the region where the three inclined weld beads 31 overlap with each other is reduced, the heat input to the first weld bead 1 can be further reduced, and the strength of the weld metal can be prevented from being lowered.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by the following description.
[Example]
As the base material 4, high strength steel using TMCP is used. In the preparation step S <b> 0, the end surfaces of the two base materials 4 are opposed to each other and are formed in the groove 5.
As the first welding step S <b> 1, the first weld bead 1 having a welding beam width of 2 mm was formed in parallel to the groove 5 so as to include the groove 5. Welding was performed at the acceleration voltage of 130 to 170 kV, the beam current of 80 to 180 mA, and the welding speed of 200 to 450 mm / min, which are the conditions in Table 1.
As the second welding step S2, after the first welding bead 1 is sufficiently cooled, the second welding bead 2 having a welding beam width of 2 mm is first welded at a biased position where the center line O1 of the first welding bead 1 is not included. The center line O1 of the first weld bead 1 and the center line O2 of the second weld bead 2 were formed so as to be parallel in a longitudinal sectional view while in contact with the bead 1.
As the third welding step S3, the third welding bead 3 having a welding beam width of 2 mm is in contact with the first welding bead 1 at a position shifted from the center line O1 of the first welding bead 1 to the side opposite to the second welding bead 2, The center line O1 of the first weld bead 1 and the center line O3 of the third weld bead 3 were formed to be parallel in a longitudinal sectional view. The welding conditions were the same as in the first welding step S1.

[Comparative example]
As the base material 4, high strength steel using TMCP is used. The first weld bead 1 having a welding beam width of 2 mm was formed on the groove 5 of the base material 4 so as to include the groove 5 as the first welding step S1. As in the case of Example 1, welding is performed at the acceleration voltage of 130 to 170 kV, the beam current of 80 to 180 mA, and the welding speed of 200 to 450 mm / min.
The second welding step S2 and the third welding step S3 are different from the examples in that they are not constructed.

FIG. 3 shows the strength test results of the comparative example and the electron beam welding example.
In the example, welding with a weld bead width of 4 mm was performed on the groove 5 by sequentially performing the first welding step S1 to the third welding step S3. Moreover, in the comparative example, since only the first welding step S <b> 1 was performed, welding with a weld bead width of 2 mm was performed on the groove 5.
As shown in FIG. 3, the strength of the weld metal was compared between the electron beam welding of the example and the comparative example. The example showed higher strength than the comparative example and was found to be about 1.06 times stronger.

  From these results, it was found that the width of the weld bead can be formed wide while preventing a decrease in strength. Moreover, it turned out that the fall of intensity | strength can be prevented by making it the 2nd welding bead 2 and the 3rd welding bead 3 not mutually overlap. In addition, the weld bead width is set to a constant width as thin as 2 mm from the first weld bead 1 to the third weld bead 3, and welding is performed without any change while preventing a decrease in strength. It was found that welding was possible.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations of the embodiments in the embodiments are examples, and the addition and omission of configurations are within the scope not departing from the gist of the present invention. , Substitutions, and other changes are possible. Further, the present invention is not limited by the embodiments, and is limited only by the scope of the claims.

In the present embodiment, the second welding step S2 and the third welding step S3 for forming the secondary weld bead may be repeated a plurality of times. For example, a fourth weld bead is formed on the opposite side of the second weld bead 2 from the first weld bead 1, and a fifth weld bead on the opposite side of the third weld bead 3 from the first weld bead 1. May be formed. That is, the number of welding processes for forming the secondary weld bead is not limited, and the sixth weld bead and the seventh weld bead may be formed in accordance with the base material to be welded and the environment in which it is used.
In addition, it is more preferable that the secondary weld bead to be constructed is not sequentially formed on one side with the center line O1 of the first weld bead 1 as a boundary but sequentially formed on the left and right.

O1 ... center line of the first weld bead 1 ... first weld bead 2 ... second weld bead 3 ... third weld bead 4 ... base material 5 ... groove 21 ... second inclined weld bead 31 ... third inclined weld bead S0 ... Preparation step S1 ... First welding step S2 ... Second welding step S3 ... Third welding step S21 ... Second inclined welding step S31 ... Third inclined welding step

Claims (2)

A step of constructing a primary weld bead so as to include a groove formed in a butt portion of two base materials;
A plurality of secondary weld beads having the same width as the primary weld bead, and a step of sequentially applying the plurality of secondary weld beads to a position where the plurality of secondary weld beads do not overlap with each other .
An electron beam welding method , wherein the secondary welding bead is applied while being inclined on the opposing surfaces of the groove of the two base materials . The electron beam welding method according to claim 1 , wherein the width of the primary welding bead and the secondary welding bead is set in a range of 1 mm to 3 mm.

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