JP3114958B2 - High efficiency fillet welding method for thick steel plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high efficiency fillet welding method for a thick steel plate, and more particularly, to a method for performing a simple groove process and performing a T-type fillet submerged arc welding of a thick steel plate in one pass on both sides. The present invention relates to a high efficiency fillet welding method for a steel sheet.

[0002]

2. Description of the Related Art In recent years, high-rise buildings have been constructed in various places, and accordingly, the thickness of steel materials used has gradually increased. For example, a so-called box pillar used as a pillar has a plate thickness of 100 mm. In addition, the thickness of the H-shaped steel used as a beam is also increasing, and therefore, improving the efficiency of assembling members used for a high-rise building is a major problem.

[0003] In general, the fillet weld of a welded H-section steel called a built-in H is formed by partial penetration welding or full penetration welding, and the welded H-section steel used for a heavy structure of a crane girder is usually completely welded. It is constructed by penetration welding. This perfect penetration welding method is already known for a case where the web is relatively thin, for example, Japanese Patent Publication No. 56-3702.
No. 9 publication. This is intended to prevent pits and blow holes when a primer steel plate is welded using a small-diameter wire, and the purpose thereof is slightly different from the purpose of the present inventors.

[0004]

Conventionally, when the thickness of a web is increased, a groove is generally formed on the web side, and after a multi-layer front welding, a back gouging, and a grinder finish, a multi-layer back welding is performed to obtain a complete penetration. Although a method has been adopted, each step such as beveling, gouging, and grinder finishing is indispensable, and it has been difficult to improve the arc time rate as well as to save labor.

[0005] By the way, there are various problems when trying to achieve simple beveling and one-side welding on both sides without gouging for complete penetration of fillet welding of a thick steel plate. Generally, in the case of fillet welding of a thin H-section steel, a molten flux is often used. This is because the molten flux has a lower melting point and is more suitable for high-speed welding, but has a drawback that the higher the speed is, the more likely it is to form a convex bead with a narrow bead width. In order to prevent this, it has been devised to expand the bead width by foaming the flux and making it lighter.However, since the melting point is low, the slag increases too much in thick large heat input welding to obtain a bead with a good appearance. There is a problem that is difficult.

On the other hand, the sintering type flux is generally a high melting point and suitable for large heat input welding since it is a mixed binder of a simple oxide or a carbonate in the manufacturing method. In addition, since penetration must be ensured in full penetration welding, the base material dilution is inevitably increased, and there is also a problem that a steel sheet having a large amount of C tends to cause high-temperature cracking. Hot cracking is greatly affected not only by the chemical composition of the weld metal but also by the cross-sectional shape of the bead, and tends to occur when the penetration depth (P) is large relative to the bead width (W), that is, when W / P is small. . Therefore, there is a problem that the bead width must be made as large as possible in order to prevent hot cracking.

An object of the present invention is to solve the above problems, and more specifically, to propose a highly efficient fillet welding method for a thick steel plate by performing simple beveling.

[0008]

According to the present invention, a C content is 0.18.
butt the following web steel plate and flange steel sheet thickness 60mm beyond 100mm in a T-shape containing the following wt%, per To both sides one pass submerged arc welding with two electrode method,
On both sides of the web steel sheet, a depth of 0.30 to 0.40 times the sheet thickness
The following pole (T pole) with respect to the leading pole (L pole) is provided using the following sintering flux (A) and wire (B).
The receding angle 3 ° to 15 ° current ratio (I _T / I _L) to the leading electrode under the conditions of 0.65 to 1.00 of the pole), the trailing electrode 3 °
A highly efficient fillet welding method for thick steel plates, characterized in that welding is performed by a complete penetration method with an advancing angle of up to 20 °. (A) Firing type flux: The total amount of each component of SiO ₂ , MgO and CaO is 45 to 6
5 wt%, total amount of each component of TiO ₂ , Al ₂ O ₃ , CaF ₂ is 5 to 20 wt%, and various metal powders are 25 to 38 w
t%, the amount of gas generated by thermal decomposition of the added material during welding is 5 to 15 wt%, and the balance is flux which is an unavoidable impurity, and the median diameter of particles having a cumulative particle size distribution of 50 wt% is 500 to 800 μm, Fired flux in which particles having a particle size of 295 μm or less are 15 wt% or less of the entire flux. (B) Wire The wire C content (wt%) is C ₁ , and the web steel sheet C content (wt)
%) As C ₂ (≦ 0.18 wt%) and the C content (wt%) of the flanged steel sheet as C ₃ (≦ 0.18 wt%), and 0.50C ₁ + 0.28C ₂ + 0.22C ₃ ≦ 0.120 C amount and Mn: 1.20 to 2.50 satisfying
4.8 to 6.4 mmφ wire including wt% Here, only the leading electrode is 5 ° to 15 ° on the flange side.
It is preferable that the welding be performed at a position inclined from the intersection of the web surface and the flange surface by a distance of 5 to 15 mm from the intersection of the web surface and the flange surface with the leading electrode and 2 to 12 mm apart from the trailing electrode.

[0009]

The following is a detailed description of the constitution as the means of the present invention and its operation. The present inventors have studied a method of performing a simple groove processing and efficiently filling a thick steel plate with a fillet submerged arc welding, and a firing type flux containing specific various components,
It has been found that two-electrode submerged arc welding may be performed using a wire having a specific component and a wire diameter, and has already been disclosed in JP-A-5-57448. However, it has been found that when the applied plate thickness is further increased, a good weld cannot be obtained without stricter restrictions. Therefore, further research and development have been carried out, and the present invention has been established based on this research.

According to the research results of the present inventors, the following has become clear. (1) To prevent hot cracking of thick steel plates and increase the bead width, it is necessary to control the chemical composition of the sintering flux and the wire diameter within a certain range. The heat input becomes large, and the limit C amount for preventing hot cracking becomes low. (3) To prevent slag entrainment, use a large diameter wire and round the penetration bottom (large radius of curvature) If the penetration bottom is sharp (small radius of curvature), slag entrapment is likely to occur and high temperature cracking is also likely to occur. In addition, large diameter wire is advantageous in increasing the bead width. there (4) in the second electrode submerged arc welding, the leading electrode (L pole), current ratio of the trailing electrode (T poles) (I _T / I _L) also affects the slag inclusion, there a constant ratio Slag entrapment is less likely to occur (5) Further, by providing a fixed angle to the leading and trailing pole torches, a bead with good penetration and good appearance can be obtained. (6) As the plate thickness increases, self-restraint increases and hydrogen cracking occurs. (7) If the target position of the wire is further limited to the condition of (5), a bead having a good appearance can be obtained with a deeper penetration even with a smaller current. as a result of the overall the various studies of, perform only simple beveling, gouging, without processes such as grinder, it was completed a method of performing a full penetration fillet weld on both sides one pass.

Hereinafter, the method of the present invention will be described in detail.
First, the flux used in the method of the present invention will be described. The flux needs to keep the bead appearance good, but SiO _{2 serving} as a base as a slag-making agent has the effect of widening the bead width and keeping the bead surface smooth. MgO is an important component for increasing the melting point of the generated slag, improving the workability during large heat input welding, increasing the basicity of the flux, reducing the oxygen content of the weld metal, and improving the toughness. C
aO improves the fire resistance of the generated slag like MgO,
Important as a component to increase the basicity of the flux,
CO that reduces the amount of diffusible hydrogen if added as aCO _3
2 It is also effective as a source. Each of these important components is required to have a certain amount or more in terms of the flux composition. From the viewpoint of bead appearance and flux fire resistance, these components are added in a total amount of 4%.
It is necessary to contain 5 wt% or more. On the other hand, if the total amount of these components exceeds 65 wt%, the flux melting point becomes too high, the bead width becomes narrow, and the appearance deteriorates.
The value of the total amount of each component of SiO ₂ , MgO and CaO is 45
６５65 wt%.

TiO ₂ is a component that improves slag removability and has an arc stabilizing effect, and Al ₂ O ₃ is an important component that adjusts slag viscosity. In addition, CaF ₂
Is also an important component in controlling the fluidity of the slag. If the total of these components is less than 5% by weight, the slag removability deteriorates, or the viscosity of the slag is too large to obtain a bead having a good appearance. The total amount of these components is 20 wt%
On the contrary, if the viscosity exceeds slag, the slag viscosity becomes too small or the arc becomes unstable, so that TiO ₂ , Al ₂ O ₃ , CaF
The value of the total amount of ₂ was 5 to 20 wt%.

In addition to these slag components, a deoxidizer,
25 metal powders to increase alloying elements and deposition amount
It is necessary to add more than wt%. This addition amount is 25wt
%, It is not only difficult to secure the toughness of the weld metal, but also it is not possible to secure a sufficient welding amount to fill the groove within the normal range of welding conditions. On the other hand, if it exceeds 38% by weight, the melting point becomes too high and a good bead cannot be obtained. Therefore, the content of the metal powder is 25 to 38 wt%. Powders such as iron powder, ferromanganese, ferrosilicon, and ferrotitanium are used as the metal powder.

The gas contained in the form of carbonate is necessary to reduce the amount of hydrogen in the weld metal. However, if the gas amount is less than 5 wt%, the effect is poor. Raising of the bead causes deterioration of the bead shape.
Therefore, the gas generation amount was set to 5 to 15 wt%. This value is smaller when the plate thickness is small, but lower hydrogenation is required when the plate thickness is large.

Although the above composition was found to exhibit good welding workability, the powder properties were further examined in order to stabilize the arc and obtain a wide bead free from defects. It was also found that it was important to limit the particle size configuration. That is, the particle size composition of the flux significantly affects the welding workability, and the median diameter is 500 μm.
If it is smaller, the flux melting amount increases, and moreover,
Since the flux fluidity deteriorates, escape of gas from the arc cavity becomes difficult and the arc becomes unstable. on the other hand,
If it exceeds 800 μm, the arc becomes too coarse and the melting becomes non-uniform, so that the arc becomes unstable also in this case. Therefore,
The median diameter of particles occupying 50 wt% in the flux cumulative particle size distribution was in the range of 500 to 800 μm.

In the fine particles unavoidable in production, 29
If the diameter is 5 μm or less, it must be 15% by weight or less. In the case of welding without beveling, the most problematic problem is that a large amount of C is contained in the weld metal because of the large amount of dilution of the base metal, and high-temperature cracking is likely to occur when the amount of C in the weld metal is large. Therefore, the key point of the technique of the present invention is how to prevent the occurrence of hot cracking.

Since the component that most affects the cracking is the C content, the C content in the weld metal must be reduced. In one-pass submerged arc welding on both sides of a T-shaped fillet with a large welding heat input as in the present technology, the C content of the weld metal is greatly affected by the C content of the base material because the dilution of the base material is large.
Unless the amount of wire C is adjusted according to the amount, it is difficult to prevent cracking. After setting all the conditions described below, when applying the present technology, the dilution amount of the base material was measured for various plate thicknesses, and the dilution ratio on the web side was 28% at the maximum,
Further, the dilution ratio on the flange side was 22% at the maximum. When the calculated C amount at which cracking occurs was determined by a restrained cracking test, it was found that cracking could be prevented if the calculated C amount was 0.120 wt% or less. At this time, the analysis value of the C content in the weld metal is 0.110 wt% or less. However, in actual welding, C and O are released as CO gas or CO ₂ gas due to the reaction between C and O in the molten pool. The amount will be low.

That is, the amount of wire C (C ₁ (wt%))
It must satisfy _{0.50C 1 + 0.28C 2 + 0.22C 3} ≦ 0.120 (1). Here, C ₁ : wire C amount (wt%) C ₂ : C amount of web steel plate (wt%) C ₃ : C amount of flange steel plate (wt%) When the C content of the web steel plate or the flange steel plate is large, the limit of reduction of the C content of the wire is exceeded, so that the base material C content needs to be 0.18 wt% or less on both the web and flange sides.

The amount of Mn in the wire is determined based on the base material M
Regardless of the amount of n, it is 1.20 to ensure the deoxidizing effect and strength.
It must be 2.50 wt%. If the content is less than 1.20 wt%, deoxidation tends to be insufficient, and the strength of a low C weld metal is hardly obtained. On the other hand, if the content exceeds 2.50 wt%, the strength becomes too high, and low-temperature cracking accompanying the increase in hardness is likely to occur. Therefore, the amount of Mn in the wire was set to 1.20 to 2.50 wt%. With respect to a wire diameter of less than 4.8 mmφ, there is a problem that an arc is thin and a bead width is hardly obtained. Further, the shape of the penetration bottom becomes sharp, and defects such as slag entrainment are likely to occur. Therefore, the wire diameter is 4.
It is necessary to be 8 mmφ or more. On the other hand, if it exceeds 6.4 mmφ, the rigidity is too large and a load is excessively applied to the welding machine, so the wire diameter was set to 4.8 to 6.4 mmφ.

Next, the submerged arc welding method will be described. Leading pole (L pole), trailing pole (T pole) by two-electrode method
Current ratio was set to (I _T / I _L) of 0.65 to 1.00 for the following reasons. That is, I _T / I _L is 0.65
If it is smaller, slag entrainment caused by the leading pole cannot be floated at the subsequent pole, and as a result, slag entrainment is likely to occur. On the other hand, I _T / I _L is 1.0
If it is larger than 0, the current of the T pole itself is large, so that the T pole causes slag entrainment. Therefore, the current ratio I _T /
The I _L was 0.65 to 1.00. Also, the leading pole is 3 °
By providing a receding angle of １５15 ° and an advancing angle of 3 ° to 20 ° on the trailing electrode, penetration is deep, and a bead having a good bead cross-sectional shape and appearance can be obtained. did.

Further, only the leading pole is inclined by 5 ° to 15 ° toward the flange side, and the leading pole is 5-1 from the position where the web surface and the flange surface intersect to above the flange surface.
Welding with 5 mm and trailing electrode 2 to 12 mm away from each other provides deeper penetration with less current compared to the welding method in which the leading electrode is not inclined to the flange side, and a bead with good bead cross-sectional shape and appearance. Is obtained.

Even if the above conditions are set, the web must be slightly grooved in order to apply the complete penetration method to a steel plate having a web thickness of more than 60 mm. That is,
In the case where a groove with a depth of 0.3 to 0.4 times the web thickness is not formed on both sides, welding must be performed with extremely deep penetration, which is practically impossible. The bead from both sides can be completely wrapped by subjecting the web side to beveling with a depth of 0.3 to 0.4 times the web thickness. If the depth of the groove processing is smaller than 0.3 times the web thickness, the penetration must be deepened, resulting in a narrow bead and a large amount of base material dilution, which tends to cause hot cracking. . On the other hand, if the groove depth exceeds 0.4 times the web thickness, complete penetration can be obtained, but a large amount of metal is required to fill the groove and improve the shape of the fillet bead. In the case of complete penetration, the beveling of the web was made to be 0.3 to 0.4 times the thickness of the web because of the lack of accuracy and insufficient joint characteristics. When the web thickness exceeds 100 mm, the web thickness is 0.3 to 0.4.
Even if a double-depth beveling is performed, directing full penetration
(A) There is a problem that hot penetration is apt to occur due to too deep penetration and a narrow bead to be formed, and (b) hot dilution is apt to occur due to a large dilution of the base material. Further, even if an alloy powder such as iron powder is added to the flux, it becomes difficult to sufficiently fill the groove and obtain a good bead.

Therefore, when the web thickness exceeds 60 mm and exceeds 100 mm,
For a steel plate having a thickness of 0.3 mm or less, a groove having a depth of 0.3 to 0.4 times the thickness of the web is machined on both sides of the web, thereby enabling a one-pass complete penetration T-type fillet high-efficiency welding on both sides. . FIG. 1 is an explanatory view showing such a T-shaped fillet welding, and includes a groove 26 mm in depth and a groove angle 4 when a web 1 having a thickness of 80 mm is welded to a flange 2 having a thickness of 80 mm.
The dimensions of the weld at 5 degrees are shown. FIG. 2 is an explanatory view showing a welded portion in which a completely penetrated T-shaped fillet welded portion 3 is applied to the web 1 and the flange 2. FIG. 3 shows the electrode angle and the target position of the wire.
The leading pole 4 is inclined from the position 5 where the surface extending from the web surface and the flange surface intersect with each other at an angle of 15 ° and upward from the flange surface.
Is 5 to 15 mm (shown by a in the figure), and the trailing electrode 6 is 2 to 1 mm.
It is a figure which shows a mode that welding is aimed aiming at the position away by 2 mm (indicated by b in the figure), (a) is a figure which looked at the welding execution state which turned 55 degrees by the angle which makes a flange side horizontal, and was seen from welding direction 7. (B) is a view seen from above the electrode, and (c) is a view seen from a direction orthogonal to the welding direction.

As described above, in the case of the thick T-shaped fillet welding, an angle formed by a horizontal angle with the flange is generally 45 ° to 45 °.
It is installed in a state of turning 70 °.

[0025]

Next, examples of the method of the present invention will be described. Embodiment 1 FIG. A calcination type flux having the chemical composition and powder characteristics shown in Table 1 was adjusted, and a JIS standard SM-490A steel sheet having a web plate thickness of 80 mm and a flange plate thickness of 80 mm shown in Table 2 was shown in FIG. like,
A groove was formed on both sides of the web at a depth of 26 mm and an angle of 45 ° to form a T-shape, and fillet welding was performed. Table 3 shows the chemical composition of the wires used, and Table 4 shows the welding conditions.

Table 5 shows the results obtained by examining the stability of the arc during welding, the appearance of the bead, the observation of the cross-sectional shape of the bead, the relationship between the oxygen content of the weld metal and the toughness, and the like.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

[Table 4]

[0031]

[Table 5]

As is clear from Table 5, according to the flux of the present invention, good fillet welding workability was obtained in each case and the toughness of the obtained weld metal was good, while the chemical composition of the flux was high. Fluxes B-1 to B-7 whose powder characteristics deviate from the proper conditions of the flux of the present invention
According to this, it was not possible to simultaneously satisfy all of the welding workability and the toughness of the weld metal.

That is, the comparative flux B-1 is made of TiO
₂ , the total amount of each component of Al ₂ O ₃ and CaF ₂ is 4.
Since the amount of generated hydrogen was small at the same time as the slag removability was low at 3%, the amount of diffusible hydrogen increased, and microcracks due to hydrogen were observed in the weld metal. Comparative flux B-
In No. ₂ , the total amount of each component of SiO ₂ , MgO, and CaO was out of the proper range, and the bead surface was severely uneven due to lack of fire resistance. In addition, the ratio of the fine-grained flux was large, the bead width was narrow, and the shape of the penetration tip was sharp, and slag entrainment was observed.

In the comparative flux B-3, 29
Since the number of particles finer than 5 μm was as large as 16.8%, gas did not easily escape during welding, and the arc was unstable. Slag entrainment was also observed. In the comparative flux B-4, the addition amount of metal powder as an alloying element and a deoxidizing agent was small,
Not only could not completely fill the groove, but also a pock mark was generated on the bead surface, and the toughness was low due to the large amount of oxygen in the weld metal.

With the comparative flux B-5, the amount of gas generated was too large, so that the blow-up during welding was severe and the arc was not stable. In addition, there were many coarse particles in terms of particle size composition, and the melting of the flux was not uniform. In the comparative flux B-6, the chemical composition is out of the proper range of the flux of the present invention, and the melting point is too high and the viscosity is too small, so that there is a large risk of breaking the beads, and the amount of gas generated is small and the amount of diffusible hydrogen is large. Therefore, micro cracks due to hydrogen were observed in the weld metal.

In the comparative flux B-7, since the amount of the alloying element and the amount of the metal powder added as the deoxidizing agent were too large, the deoxidation was excessive, and consequently, the quenching was excessive and the weld metal toughness was deteriorated. Embodiment 2. FIG. Using the flux A-2 of the present invention and the comparative flux B-1 used in Example 1, the effects of the base material, wire, and welding conditions were examined.

Table 6 shows the chemical composition of the steel sheet used, Table 7 shows the chemical composition of the wire, and Table 8 shows the welding conditions. Complete penetration T-type fillet welding was performed by appropriately combining these fluxes, steel plates, wires, and welding conditions. The results are collectively shown in Table 9.

[0038]

[Table 6]

[0039]

[Table 7]

[0040]

[Table 8]

[0041]

[Table 9]

In the present invention example, satisfactory complete penetration fillet welding without defects is possible, but in the comparative examples, there were some problems. That is, in Comparative Example G1, slag entrainment occurred because the current ratio among the welding conditions was as small as 0.63. In Comparative Example G2, the wire diameter was small, the bead width did not come out, the bead became a sharp bead, and slag was involved, and the risk of cracking was great. In Comparative Example G3, the amount of wire Mn was small, some blow holes were generated, and the strength was insufficient. In Comparative Examples G4 to G6, since the C content of the base material or the wire was large, hot cracking occurred. In Comparative Example G7, the flux A-2 of the present invention was changed to the comparative flux B-1, and the base material, wire, and welding conditions were optimally set.
A problem occurred with an internal defect. In Comparative Example G8, slag entrainment occurred because the current of the T pole was larger than the current of the L pole. In Comparative Example G9, the electrode angle was + 0 ° at the leading electrode and -25 ° at the trailing electrode, which was different from the example of the present invention, so that insufficient penetration and poor bead appearance occurred.

As described above, satisfactory results were obtained only in the range of the flux of the present invention. When this method is applied to full penetration welding when the web thickness is more than 100 mm, the penetration becomes too deep as shown in FIG. After all, hot cracking became easy to occur.

Various welding conditions were selected for the T-shaped fillet weld of 105 mm in web thickness having the same chemical composition as C-1 in Table 6 using the wire symbol D-1 in Table 7. Cracking occurred at full penetration, but plate thickness was 100mm
Until it did not crack. Therefore, according to the method of the present invention,
From 0 mm to 100 mm, the complete penetration method is applicable. Embodiment 3 FIG. Using the steel plates shown in Table 2 and the wires shown in Table 3, the effects of the wire arrangement, wire target position, and welding conditions were examined.

The welding conditions shown in Table 10 were used.

[0046]

[Table 10]

Table 11 shows the results when the inclination angles of the L and T poles to the flange side were changed.

[0048]

[Table 11]

In the second invention example, the bead wrap on both sides is sufficient with a small current, and the solidification association portion 8 is not straight but upward as shown in FIG. It can be seen that a large current is required for both the leading and trailing poles in order to obtain the same effect as the second invention example 1.

[0050]

According to the present invention, the thick T-shaped fillet submerged arc welding can be performed in one pass on both sides by simple groove processing, and it is an industrially effective technology such as cost reduction and short delivery time. is there.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing T-shaped fillet welding dimensions.

FIG. 2 is an explanatory view showing a completely penetration T-shaped fillet welded portion.

FIG. 3 is an explanatory diagram showing a wire aiming position and an electrode arrangement.

FIG. 4 is a view showing a residue of a mating surface between a web and a flange.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Web 2 Flange 3 Weld 4 Lead electrode 5 Position where web surface and flange surface intersect 6 Trailing electrode

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B23K 35/362 310 B23K 35/362 310B (72) Inventor Ryuji Okabe 2-3-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Kawasaki Steel Corporation Tokyo headquarters (72) Inventor Saburo Hayashi 2-3-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Kawasaki Steel Corporation Tokyo headquarters (72) Inventor Matsushima Nakashige 18 Showa-cho, Marugame-shi, Kagawa Prefecture 56) References JP-A-5-57448 (JP, A) JP-A-3-27891 (JP, A) JP-A-63-16870 (JP, A) JP-A-61-23597 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) B23K 9/18 B23K 9/00 B23K 9/02 B23K 33/00 B23K 35/30 B23K 35/362

Claims (1)

(57) [Claims] 1. When a web steel sheet having a C content of 0.18 wt% or less and a steel sheet having a thickness of more than 60 mm and 100 mm or less and a flange steel sheet are butt-jointed in a T-shape, two-pass one-side submerged arc welding is performed. A groove having a depth of 0.30 to 0.40 times the thickness of the web steel plate is provided on both sides of the web steel plate, and the following sintering type flux (A) and wire (B) are used. current ratio of trailing electrode (T poles) (I _T / I _L)
At a leading pole of 3 ° to 15 ° under conditions of 0.65 to 1.00.
The method for filling a thick steel plate with high efficiency, wherein the receding angle is set to a forward angle of 3 ° to 20 ° at a trailing electrode and welding is performed by a full penetration method. (A) Firing type flux: total amount of each component of SiO ₂ , MgO, CaO is 45 to 65 wt%, TiO ₂ , Al ₂ O
_3, the total amount of the components of CaF ₂ is 5 to 20 wt%, these
Deoxidizer, alloying elements and deposition amount
25-38 wt% of metal powder to increase the amount of gas, and the amount of gas generated by thermal decomposition of the added material during welding is 5-15 wt%
%, The balance consists of flux which is an unavoidable impurity,
The median diameter of particles having a cumulative particle size distribution of 50 wt% is 500 to
A fired flux in which particles having a particle size of 800 μm and having a particle size of 295 μm or less are 15 wt% or less of the entire flux. (B) Wire The wire C amount (wt%) is C ₁ , and the web steel sheet C amount (wt)
%) As C ₂ (≦ 0.18 wt%) and the C content (wt%) of the flanged steel sheet as C ₃ (≦ 0.18 wt%), and 0.50
_{C 1 + 0.28C 2 + 0.22C 3} ≦ 0,120 wire C amount and satisfying the Mn: containing 1.20~2.50wt%, of the diameter 4.8~6.4mmφ wire