JP3808213B2 - Submerged arc welding method for thick steel plate - Google Patents

Description

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【表３】

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【００３１】
【発明の効果】
以上説明したように、本発明によれば、板厚が６０ｍｍを超えるような厚板鋼板であっても、１ランで溶接することができ、また、板厚が６０ｍｍ以下の場合には溶接能率を高めることができ、良好な継手品質を得ることができる。
【図面の簡単な説明】
【図１】溶接試験方法を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a highly efficient submerged arc welding method for thick steel plates, and more particularly, to a submerged arc welding method for thick steel plates suitable for welding corner joints of steel thick plate box columns.
[0002]
[Prior art]
In recent years, design policies such as reducing the number of columns and increasing the interval between columns have been adopted for the purpose of improving habitability and effective use of space in accordance with the increase in the number of buildings. For this reason, it exists in the tendency for the plate | board thickness used for a pillar to become thick. In particular, columns used in high-rise buildings are often box-shaped, and when creating columns, the four corners are generally terminated by submerged arc welding and one run of welding. In the conventional welding technique, it is possible to secure a plate thickness of up to about 60 mm by two-electrode welding by selecting the groove shape, welding material, and welding conditions.
[0003]
[Problems to be solved by the invention]
Recently, however, a relatively large number of box columns having a thickness exceeding 60 mm have been used. In such a case, as described above, since the thickness that can be welded in one run is up to 60 mm, the bottom of the groove is preliminarily deposited by CO ₂ welding or the like, and the top is submerged arc. The welding construction method of performing one run welding by welding is adopted. However, such a construction method has a very large number of welding steps for manufacturing the column, and is therefore inefficient. Accordingly, there is a demand for the development of a high-efficiency and low-cost welding method for thick plates having a thickness exceeding 60 mm.
[0004]
The present invention has been made in view of such problems, and even when the plate thickness exceeds 60 mm, welding can be performed in one run, and in the case of a plate thickness of 60 mm or less, the welding efficiency can be increased. An object of the present invention is to provide a method of submerged arc welding of thick steel plates that can provide good joint quality.
[0005]
[Means for Solving the Problems]
The submerged arc welding method for thick steel plates according to the present invention uses two or three electrodes that ensure 100% penetration by welding one plate from one side to a thick steel plate having a thickness t (mm) of 50 mm or more. In the submerged arc welding method, a V-shaped groove is provided, the groove angle is 10 to 20 °, the gap at the groove bottom is 8 to 15 mm, the root face is 0 to 20 mm, and the wire diameter of the final electrode is 6.4 to 7.2 mm, the wire diameter of the electrodes other than the final electrode is 4.8 to 6.4 mm, and the current LI (A) of the first electrode and the current TI (A) of the electrodes after the second electrode satisfy the following formula 1. And the distance between the first electrode and the second electrode and the distance between the second electrode and the third electrode are kept at 40 to 100 mm, and iron or iron alloy powder or particles 10-25mm height in the groove Characterized by submerged arc welding and filled.
[0006]
[Expression 1]
25t ≦ LI ≦ 35t
20t ≦ TI ≦ 30t
[0007]
In this submerged arc welding method, the receding angle of the electrode slope before Symbol first electrode 2 to 10 °, it is preferable that the advancing angle of the electrode slope of the second electrode subsequent electrode 2 to 10 °.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
As a result of repeating various research experiments in order to solve the above-described problems of the prior art, the present inventors are able to solve this problem by satisfying the requirements described in the claims of the present invention. I found it. The present invention has been completed based on such knowledge. Hereinafter, the definition of the requirement or the reason for limiting the numerical value defined in the claims of the present invention will be described.
[0009]
▲ 1 ▼ by Hirakisakikatachi like especially 2 electrode welding to aim at expanding coverage of 1 run welding, without compromising the integrity of the welds, a problem or to secure a deposition rate in the how. Therefore, as a result of various investigations on the groove shape, the V-shaped groove shape has a groove angle of 10 to 20 °, a gap at the groove bottom of 8 to 15 mm, and a root face of 0 to 20 mm. It is possible to perform one-run welding to a thick plate having a thickness of about 70 to 80 mm by welding, and a sound penetration shape can be obtained.
[0010]
If the groove angle is less than 10 °, it becomes a vertically long penetration shape, and hot cracking is likely to occur. Also, the groove wall is nearly vertical, the molten metal does not fit well, poor fusion and slag entrainment occur. It becomes easy. If the groove angle exceeds 20 °, the weld cross-sectional area becomes too large, and in particular with two-electrode welding, it is impossible to ensure the amount of welding, and the applied plate thickness cannot be increased.
[0011]
If the gap at the bottom of the groove is less than 8 mm, it is difficult to ensure a stable penetration depth. In particular, when the center of the electrode is displaced from the target position, poor penetration is likely to occur. If the gap at the bottom of the groove exceeds 15 mm, the weld cross-sectional area becomes too large. Therefore, particularly in the case of two-electrode welding, the amount of welding cannot be secured, and the applied plate thickness cannot be increased.
[0012]
If the root face exceeds 20 mm, the penetration shape formed by the leading electrode becomes vertically long, and it becomes difficult to secure the penetration depth by the trailing electrode, and high temperature cracking occurs in the weld metal formed by the leading electrode. It becomes easy.
[0013]
(2) Electrode diameter 2 and 3 electrode welding, especially when welding thick plates in one run, in order to secure the amount of welding and obtain a sound penetration shape and penetration depth and good bead, The influence of the electrode diameter used for the is large. It is preferable that the diameter of the electrodes other than the final electrode whose main roles are to secure the penetration depth and the welding amount is 4.8 to 6.4 mm. When the electrode diameter is less than 4.8 mm, the current is increased. Although the welding amount can be secured, the lack of stability of the penetration depth and the narrower penetration width are disadvantageous in terms of resistance to hot cracking, and the gap at the bottom of the groove is wide. This is not preferable because poor fusion tends to occur. When the electrode diameter exceeds 6.4 mm, the penetration depth cannot be secured or the penetration becomes unstable when the gap at the groove bottom is narrow and the groove angle is small. Also, the electrode diameter of the final electrode is preferably 6.4 to 7.2 mm in order to ensure a sound penetration shape and welding amount and to obtain a good bead, and if the electrode diameter is less than 6.4 mm, the penetration depth However, a sufficient penetration width and a stable bead width and bead shape cannot be obtained. When the electrode diameter exceeds 7.2 mm, a sufficient penetration width and bead width can be ensured, but a sound penetration depth cannot be ensured.
[0014]
(3) The distance between the first electrode and the second electrode and the distance between the second electrode and the third electrode The distance between the first electrode and the second electrode is formed by the first electrode. This is important in avoiding vertical cracks in the weld metal, and is preferably in the range of 40 to 100 mm. If it is less than 40 mm, the weld metal formed by the first electrode and the second electrode is integrated, resulting in a longitudinally long shape. The weld metal is formed and hot cracking is likely to occur. If the distance between the electrodes exceeds 100 mm, a sufficient depth of penetration by the second electrode cannot be secured, so that a large amount of the vertically long weld metal formed by the first electrode remains, and vertical cracks are likely to occur.
[0015]
The interelectrode distance between the second electrode and the third electrode is important for ensuring a sound penetration depth by the third electrode and a stable and good bead, and is preferably in the range of 40 to 100 mm. When the weld metal formed by the two electrodes and the third electrode is integrated and the bead width is narrow, it becomes a vertically long penetration shape and a vertical crack is likely to occur. On the other hand, if the thickness exceeds 100 mm, the slag generated by the first and second electrodes is solidified and cannot be stably melted, resulting in uneven bead widths and an undesirable bead shape.
[0016]
(4) Current of each electrode The current used for each electrode must be selected for the purpose of securing a sufficient amount of welding according to the plate thickness, obtaining a sufficient penetration depth, and obtaining a good bead. However, the above-mentioned object can be achieved by using the currents of the respective electrodes that satisfy the following formulas for each plate thickness. When the plate thickness is t (mm), if the current of the first electrode is less than 25 t, sufficient penetration depth and necessary welding amount cannot be secured, and if the current of the first electrode exceeds 35 t, The cracks are too deep and hot cracks are likely to occur. If the current of the second electrode is less than 20 t, a sufficient depth of penetration by the second electrode cannot be ensured, so that a large amount of vertically long weld metal formed by the first electrode remains, and vertical cracks are likely to occur. When the current of the second electrode exceeds 30 t, the weld metal formed by the first electrode and the second electrode is integrated, and as a result, a vertically long weld metal is formed, and high temperature cracking is likely to occur. The melted land becomes unstable and stable bead formation becomes difficult. When the current of the third electrode is less than 20 t, a sufficient depth of penetration by the third electrode cannot be ensured, so that a large amount of vertically long weld metal formed by the second electrode remains, and vertical cracks are likely to occur. When the current of the third electrode exceeds 30 t, the melted land becomes unstable and stable bead formation becomes difficult.
[0017]
(5) Filler in the groove The filler in the groove is effective for assisting the amount of welding and further stabilizing the depth of penetration, and the component is a powdery or granular material mainly composed of iron. A thing is preferable at the point of a meltability. The filling height is preferably about 10 to 25 mm for the above purpose, and if it is less than 10 mm, the above effect cannot be obtained, and if it exceeds 25 mm, it is extremely effective in securing the welding amount, but the penetration depth is There is a problem that it cannot be secured.
[0018]
(6) Electrode inclination The electrode inclination is effective in adjusting the penetration depth and the bead width, and the first electrode, whose role is to ensure the penetration depth, has a receding angle of 2 to 10 °. In this case, a more stable penetration depth is obtained, and the second and third electrodes, whose main roles are the formation of the penetration shape and the bead, are more stable when the advance angle is 2 to 10 °. A penetration shape and a stable bead can be obtained.
[0019]
(7) Others The flux used in this method is not particularly specified as long as it is a bond flux for large heat input, but a bond flux for large heat input containing iron powder is particularly preferable.
[0020]
【Example】
Next, examples of the present invention will be described in comparison with comparative examples that are out of the scope of the present invention. Using the steel wire solid wire shown in Table 2 and the bond flux shown in Table 3, the steel plate shown in Table 1 below was subjected to one-run welding with two electrodes and three electrodes. The contents of the welding test are shown in Tables 4 to 7 below, and the results of the welding test are shown in Table 8 below. However, in Tables 4 to 7, as shown in FIG. 1, θ is the groove angle, G is the gap at the groove bottom, and S is the root face. In Tables 4 to 7, those exceeding the range specified in each claim of the present invention are indicated with an underline.
[0021]
In Examples A to M that satisfy all the provisions of claim 1 of the present invention, a weld bead having a sufficient welding amount, good appearance and shape is obtained, and the penetration depth and shape are sound and stable. It was. In addition, Example C satisfies claims 1 and 3, and the other examples satisfy all of claims 1 to 3.
[0022]
On the other hand, in Comparative Example N, since the groove angle θ was too narrow, the penetration width by the leading electrode was narrow and high-temperature vertical splitting occurred. In Comparative Example O, since the current of the leading electrode was too high, the penetration depth was excessive, the shape became a pear shape, and hot cracking occurred. In Comparative Example P, since the current of the trailing electrode was insufficient, the penetration became shallow, and a small vertical crack occurred in the vertically long weld metal formed by the preceding electrode. In Comparative Example Q, since the groove angle was too wide, the amount of welding was insufficient. In Comparative Example R, since the root face S was too large, the penetration width of the weld metal formed by the preceding electrode was narrow, and although the crack did not occur, an unhealthy penetration shape was obtained. In Comparative Example S, the gap G at the groove bottom was too narrow, and the penetration depth by the leading electrode was insufficient. In Comparative Example T, the distribution height of the filler in the groove was too high, and the penetration depth by the leading electrode was insufficient. In Comparative Example U, the electrode diameter of the trailing electrode is too large, the penetration depth becomes shallow, the vertically long weld metal formed by the preceding electrode remains, and the bead width becomes wider than necessary, which is an undesirable result. there were. In Comparative Example V, since the gap G at the groove bottom was too wide, the amount of surplus in the bead shape was insufficient. In Comparative Example W, the current of the leading electrode was too high, and the current of the trailing electrode was insufficient. High temperature vertical cracks occurred in the weld metal. In Comparative Example X, the interelectrode distance between the preceding electrode and the succeeding electrode was too wide, so that a poor fusion occurred between the weld metal formed by the preceding electrode and the weld metal formed by the succeeding electrode. In Comparative Example Y, since the distance between the leading electrode and the trailing electrode is too small, the weld metal formed by the leading electrode and the welding metal formed by the trailing electrode are integrated, and no cracks occur. However, the penetration depth became too deep than necessary, resulting in an undesirable penetration shape. In Comparative Example Z, because the current of the trailing electrode (second electrode) was too high, the welding metal formed by the leading electrode and the welding metal formed by the trailing electrode were integrated, and the penetration width was narrowed. High temperature vertical cracks occurred.
[0023]
[Table 1]

[0024]
[Table 2]

[0025]
[Table 3]

[0026]
[Table 4]

[0027]
[Table 5]

[0028]
[Table 6]

[0029]
[Table 7]

[0030]
[Table 8]

[0031]
【The invention's effect】
As described above, according to the present invention, even a thick steel plate having a thickness exceeding 60 mm can be welded in one run, and if the thickness is 60 mm or less, the welding efficiency is improved. And good joint quality can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing a welding test method.

Claims (2)

In a submerged arc welding method using two or three electrodes that secure 100% penetration by welding one run from one side of a thick steel plate having a thickness t (mm) of 50 mm or more, a V-shaped groove is provided, The groove angle is 10 to 20 °, the gap at the groove bottom is 8 to 15 mm, the root face is 0 to 20 mm, the wire diameter of the final electrode is 6.4 to 7.2 mm, and the wire diameter of the electrodes other than the final electrode is 4 .8 to 6.4 mm, the current LI (A) of the first electrode and the current TI (A) of the electrode after the second electrode are set so as to satisfy the following formula, and the first electrode and the second electrode The inter-electrode distance and the inter-electrode distance between the second electrode and the third electrode are maintained at 40 to 100 mm, and iron or iron alloy powder or particles are filled in the groove to a height of 10 to 25 mm and submerged. Thick steel plate characterized by arc welding Submerged arc welding method.
25t ≦ LI ≦ 35t
20t ≦ TI ≦ 30t   2. The thick steel plate according to claim 1, wherein the electrode inclination of the first electrode is a receding angle of 2 to 10 °, and the electrode inclination of the electrodes after the second electrode is an advancing angle of 2 to 10 °. Submerged arc welding method.

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