JPH11254183A - Bond flux for submerged arc welding and method for producing the same - Google Patents

Abstract

(57) [Summary] [Problem] In submerged arc welding of large heat input of steel,
The present invention relates to a bond flux capable of stably obtaining a large penetration depth and a method for producing the same, providing a bond flux having an appropriate particle size composition and a bulk specific gravity, and providing a method of using a raw material having an appropriate particle size to produce the bond flux. I do. SOLUTION: This is a bond flux for submerged arc welding, wherein 60% or more of coarse particles having a flux particle diameter of 0.3 to 2.4 mm and 15% or less of fine particles having a flux particle diameter of 0.10 mm or less are the total weight of the flux. And the flux has a bulk specific gravity of 1.15 to 1.45. Also,
The raw materials for flux are classified into coarse-grained raw materials and fine-grained raw materials, and the particle diameter of coarse-grained raw material A: 0.25 to 1.4 mm, fine-grained raw material B:
0.1 mm or less, the blending ratio of the coarse-grained raw material A and the fine-grained raw material B is 1.5 ≦ B / A ≦ 8.5, and the blending ratio of the coarse-grained raw material A is 7 to 33%. Rolling granulation is performed by adding a binder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bond flux for submerged arc welding used for butt welding of mild steel or high-strength steel and for a square joint of a box column. More specifically, the present invention has a large penetration even in a narrow groove and a large penetration. The present invention relates to a bond flux for submerged arc welding (hereinafter, referred to as a bond flux), which is excellent in welding workability in heat input welding and can obtain a sound weld without a welding defect, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, the thickness of a steel material to be applied has been increased due to an increase in the size of a steel structure or an increase in the height of a building structure. For example, a box pillar used for a pillar member of a high-rise building may use a steel material having a plate thickness of about 100 mm, and a welding method for finishing such a steel material with as few welding passes as possible has been desired. At present, the range of 1 pass welding finish is 60 mm maximum thickness for 2 electrode welding.
In the case of three-electrode welding, up to a plate thickness of about 80 mm has been put to practical use.

[0003] As one-pass welding of such a box column corner joint, for example, Japanese Patent Laid-Open No. 1-241380 discloses a groove shape, welding conditions, flux composition, etc.
Submerged arc welding (submerged arc welding) of a corner joint enabling welding of 0 mm or more is disclosed. Further, Japanese Patent Application Laid-Open No. 2-258191 discloses that, mainly by limiting the composition and particle size distribution of the flux, and by limiting the welding current and the groove shape, good welding workability is obtained and defects in the welded portion are prevented. Techniques are disclosed.

[0004] However, in box column corner joint welding, it is difficult to obtain a stable penetration when performing welding with a large plate thickness by conventional welding. That is, in the case of two-electrode welding with a plate thickness of 60 mm,
Although the current exceeding 000A is used, the penetration variation is large in the full penetration weld that dissolves to the groove bottom,
In some cases, there is a problem that the penetration is insufficient, or in an extreme case, the penetration becomes too large to cause a hot crack at the central portion of the weld metal.

Further, the present invention is characterized in that the composition ratio of the coarse-grained material and the fine-grained material in the raw material used for the bond flux is specified, and the bulk specific gravity and the particle size configuration of the flux are controlled. However, since the conventional bond flux particles simultaneously mix various fine powders, the flux particles usually have a form in which individual raw materials are randomly dispersed throughout the particles.

As a technique for controlling the particle morphology of the flux, Japanese Patent Publication No. 42-4565 discloses a flux in which the usability is improved by coating a granulated and fired central core particle with a specific component material. In Japanese Patent Application Laid-Open No. 51-119640, a flux obtained by adhering an inorganic binder to a molten flux of a specific component is disclosed in JP-A-63-252693. Japanese Patent Application Laid-Open No. 4-313490 discloses an iron powder-containing bond flux in which iron or an iron alloy having a specific specific surface area value is disposed as a granulation nucleus at the center of each flux particle, and the iron component obtained by firing at a high temperature is heated. A bond flux that prevents oxidation and realizes low hydrogenation is disclosed.

Japanese Patent Application Laid-Open No. Hei 6-23585 discloses that iron or iron having a specific specific surface area value as a granulation nucleus and a coarse median particle size in the center of each flux particle in an iron powder-containing bond flux. A method of manufacturing a bond flux in which an iron alloy is provided and oxidation of iron components due to high-temperature sintering is prevented to achieve low hydrogenation is disclosed. But,
Any of the above disclosed techniques has a problem in obtaining a stable penetration depth and good welding workability at the same time.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a stable penetration depth and good welding workability can be simultaneously obtained in a large current submerged arc welding exceeding 2000 A, which is a problem of the conventional bond flux described above. An object of the present invention is to provide a manufacturing method which solves the problem and obtains the particle size and bulk specific gravity of the bond flux.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides a flux having a proper grain size, a proper bulk specific gravity, and a coarse grain to obtain a good weld in a large current submerged arc welding exceeding 2000 A. Another object of the present invention is to provide a flux production method using a raw material and a fine-grained raw material at an appropriate ratio.

[0010] The gist is that, in the bond flux for submerged arc welding, 60% or more of coarse particles having a flux particle diameter of 0.3 to 2.4 mm in total weight% of the flux.
Flux particle size: 15% or less of fine particles having a diameter of 0.10 mm or less, and a bulk specific gravity of the flux is 1.15 to 1.45, and further, production of a bond flux for submerged arc welding. In the method, the compounding raw material for the flux is divided into a coarse-grained raw material and a fine-grained raw material, and the particle diameter of the coarse-grained raw material A is set to 0.25 to 1.4 mm and the fine-grained raw material B is set to 0.1 mm or less. The blending ratio of A and fine-grained raw material B is set to 1.5 ≦ B / A ≦ 8.5, and the blending ratio of coarse-grained raw material A is 7 to 33%. And manufacturing the bond flux for submerged arc welding by rolling and granulating.

[0011]

DETAILED DESCRIPTION OF THE INVENTION
In large current submerged arc welding exceeding A, in order to obtain a stable and large penetration depth, flux composition, particle size composition, bulk specific gravity and welding current, voltage, speed, wire inclination angle, protrusion length, We examined from both aspects of welding conditions, such as the distance between the poles, how to take the ground, and the method of connecting the electrodes.

[0012] First, the cause of the variation of the penetration depth in such a large current welding exceeding 2000 A was investigated. Compared to the welding of thin plates with relatively small working current,
In high-current welding exceeding 2000 A used for a plate thickness of 50 mm or more, the penetration depth tends to vary greatly. From this viewpoint, as a component of the flux whose penetration depth increases, the content of MgO and TiO ₂ is relatively high, and the SiO ₂ composition that increases the penetration based on the conventional bond flux for large heat input is increased to increase the penetration. The bond flux in which the MgO composition to be reduced was reduced and Al ₂ O ₃ was adjusted was put to practical use. Furthermore, in order to stabilize the penetration depth of the flux, the relationship between the penetration depth was examined by focusing on the particle size composition and the bulk specific gravity of the bond flux. As a result, a clear relationship was found between the bulk specific gravity and the penetration depth.

That is, FS- of JIS Z 3352
17% SiO ₂ -15% TiO _2- specified in BT1
The _{11% MgO-14% Al 2} O 3 -28% Fe -based flux-based, water glass amount, rolling granulation time, and granulated by changing the bread rotational speed in granulation, further sieving Prototype bond flux divided and sized to 1.4 mm to 0.1 mm, groove angle: 35 °, root face: 2 mm
JIS Z, a steel plate with a thickness of 50 mm and a length of 1500 mm
Using a 2.0% Mn-based steel wire of 6.4 mmφ specified in 3351 YS-S6, L electrode: 2050A-3
9V, T electrode: 1650A-50V, welding speed 25cm /
Welded with two electrodes of min. One section macro was taken from each of 450 mm, 750 mm, and 1050 mm from the start end of the weld bead, and the penetration depth was examined.

FIG. 1 shows the results. As is clear from the figure, when the bulk specific gravity of the flux is small, the variation in the penetration depth is large, and when the bulk specific gravity is large, the variation in the penetration depth is small and the flux is stable. In submerged arc welding, an arc is generated between the wire and the base material to melt the wire, base material and flux,
An arc cavity is formed in the melted portion to perform stable welding.

There are molten slag, semi-solidified slag, and flux on the arc cavity. If the bulk specific gravity of the flux increases, the arc cavity becomes smaller, the arc is narrowed, and the arc is concentrated at the bottom of the groove. It is presumed that it becomes stable as the size increases. Therefore,
In order to obtain a stable penetration depth, it is necessary to stably increase the bulk specific gravity of the bond flux used.

From these viewpoints, as a measure for improving the granulation property of the bond flux, the present inventors conducted an experiment on the granulation property by tumbling granulation using various raw materials, In this case, a suitable range of the particle size composition and the composition ratio was obtained. These results are shown in FIG. The finished flux is 0.3 to 2.4 mm under the usual welding conditions.
The degree is appropriate and this particle size range was assumed.

For this purpose, first, the core material is a raw material having a particle diameter of 0.25 to 1.4 mm, and the particle diameter of the raw material adhered and granulated around the core as a core material is If the particle size of the is less than one tenth or less of 0.1 mm or less, the granulation properties are improved. In other words, if the raw material for such fine particles is 1.5 to 8.5 times the raw material for coarse particles serving as nuclei, even better granulation properties can be obtained. Coarse particle size 0.25
If less than 0.02 mm to work as a nucleus
It is necessary to select a raw material having a particle diameter of not more than mm, and selection of the raw material is restricted, so that it is difficult to select the raw material as a normal raw material. Also, 1.4mm
If it is larger, the particle size of the flux becomes larger by 2.4 mm, and the bead appearance becomes poor in welding.

When the composition ratio of the raw material of the coarse particles in the flux is less than 7% by weight, the number of particles serving as nuclei is small. Therefore, the remaining fine particles are separated into granules by agglomeration. However, the former is completed in a short time, whereas the latter is slow in progress, and the two are mixed, so that it is difficult to obtain a stable particle size configuration. Therefore, the bulk specific gravity is not stable, and good welding results cannot be obtained.

On the other hand, the composition ratio of the raw material of the coarse particles is 37%.
If it exceeds, the nuclear material becomes excessive and the number of particles agglomerated there is reduced, so that the component segregation of the flux increases and the particle size does not become stable.

The particles to be aggregated have a particle diameter of 0.10.
If the raw material is not more than mm, the effect can be exhibited, and if it is larger than this, aggregation is not performed stably. In addition, if the composition ratio is less than 1.5 with respect to the raw material having a particle size of 0.25 to 1.4 mm, the coagulated substance is insufficient and a stable particle size configuration is not obtained. When added, the amount of fine particles as an agglomerated substance becomes excessive with respect to the coarse particles serving as nuclei, and a stable particle size configuration is not obtained. Therefore, the mixing ratio of the coarse-grained raw material A and the fine-grained raw material B is set to 1.5 ≦ B / A ≦ 8.5.

As the raw material of the coarse particles, metal oxides and metal fluorides are desirable, and when the bulk specific gravity is large, such as iron, iron alloy and metal powder, it is not desirable. That is, these raw materials have a bulk specific gravity of 3.5 or more, and when added, the bulk specific gravity of the flux becomes excessively large, so that projection-like defects are generated on the bead surface, which is not desirable. Further, as the fine-grained raw material, a compounding raw material usually used in bond flux may be used.

Next, in order to obtain a weld bead having a good bead shape and appearance by a square joint welding of a box column having a plate thickness of 60 mm, the flux used in the above-mentioned manufacturing method has a particle diameter of the same. 0.3-2.4mm
Is required to be 60% or more, and the composition ratio having a particle diameter of 0.10 mm or less is 15% or less. In large heat input welding, particles having a particle size of 0.3 to 2.4 mm are the most important and determine the appearance and shape of the weld bead. That is, if the composition ratio is less than 60%, the bead appearance deteriorates. If the proportion of particles having a particle diameter of 0.10 mm or less exceeds 15%, abnormal blow-up occurs during welding, and the bead shape is deteriorated.

Further, in order to obtain a stable penetration and a defect-free weld by square joint welding of a box column having a thickness of 60 mm, the bulk specific gravity of the flux needs to be 1.15 to 1.45. . During welding, the arc cavity is subjected to pressure by the flux. That is, when the bulk specific gravity increases, the arc cavity receives a large pressure from the flux, and the arc concentrates and the penetration depth increases. If the bulk specific gravity is less than 1.15, a stable penetration depth cannot be obtained, but if the bulk specific gravity exceeds 1.45, a large penetration can be obtained, but the concentration of the arc becomes excessive, so that the weld bead spreads. Is not obtained, and the shape and appearance deteriorate.

Based on these findings, the present inventors have studied a method for producing a bond flux for obtaining a stable bulk specific gravity in the bond flux. First, as a method of granulating the bond flux, water glass is added to the powdery and granular material, mixed, and the wings are rotated in a cylindrical container, the raw material is pressed against the container wall, and the material is rolled along the container wall. Typical examples include mixer granulation to granulate and bread granulation in which the raw material is mixed with water glass and poured into a dish-shaped container, and the dish-shaped container is rotated at a slight angle to roll the raw material on the container surface. Rolling granulation method, and extrusion granulation, in which water glass is added to a powdery raw material, and the mixed raw material is inserted into a cylinder and passed through a screen having an appropriate aperture by pressure to granulate the raw material. .

In the case of tumbling granulation, the raw material particles are used as a binder.
Agglomerated through, another agglomerated particle or raw material further aggregates into agglomerated particles to become larger particles, but due to fluctuations in the amount of binder added to the raw material during granulation or granulation time, etc.
The particle size and specific gravity of the resulting flux vary.
Therefore, in rolling granulation, it is necessary to strictly control the amount of the binder, the granulation time, and the like.

The present invention provides a production method for obtaining a stable particle size composition and bulk specific gravity in tumbling granulation.
First, the regulation of the particle size of the compounding raw material used will be described. In the case of tumbling granulation, the raw material particles are agglomerated into particles via a binder, and the particles are also agglomerated into larger particles. By taking in particles, the particle size grows more and more. In the production of the bond flux, the granulation is terminated and used when the flux particles have grown to a predetermined size in the process of agglomerating and increasing the size of the raw material, instead of using the particles whose particle diameter has completely grown.

As a raw material of the bond flux, a raw material having a particle diameter of usually 0.1 mm or less is used, and is granulated to a concentration of 0.15 to 0.15.
Generally, the flux has a particle diameter of about 1.4 mm. In this case, in the production of bond flux, since various raw material powders having a fine particle diameter of 0.1 mm or less and having a relatively small difference in particle diameter are simultaneously mixed, it is not necessary to use particles in which the flux particles have completely grown. In dynamic granulation, the raw materials are dispersed randomly throughout the flux and are unlikely to become the core of agglomeration.Therefore, agglomerates of particles having different agglomeration stages from the initial stage of granulation exist, and the agglomeration rate thereafter is low. Due to the difference, the resulting flux is agglomerated, and particles having a large particle diameter and particles having a relatively small particle diameter in the initial stage of aggregation are mixed, so that the particle size configuration covers a wide range.

That is, it is difficult to strictly control the particle size composition of the flux by the production conditions such as the amount of water glass and the granulation time, and the bulk specific gravity varies because the particle size composition covers a wide range. For this reason, if it is necessary to control the penetration depth strictly, as in the case of a flux for welding corner joints of a box column with a thickness of 60 mm, after granulation,
The flux was sieved and blended to adjust the particle size to a predetermined value, thereby producing the product.

In order to solve this problem and strictly control the particle size composition of the flux in the manufacturing process, a raw material having an appropriate particle diameter serving as a core of agglomeration is added to a conventionally used raw material having a relatively small particle diameter and mixed in advance. Then, it was found that it can be obtained by adding a binder and granulating. In other words, in place of the aggregate having a particle diameter that becomes a nucleus that the particles grow to some extent by repeating aggregation and are slightly smaller than the particle diameter of the intended flux, a relatively large particle having a particle diameter is added as a raw material,
Further, by mixing particles having a relatively small particle diameter that aggregates in the nucleus in an appropriate ratio, control of the particle diameter of the flux becomes possible.

That is, if the above coarse-grained raw material and fine-grained raw material are combined in an appropriate ratio, the flux granulation step grows to some extent, and the step of forming an aggregate having a core particle diameter is almost omitted. The process in which the fine particles agglomerate through the binder and the particle diameter grows with the core of the particles as the core becomes dominant,
The presence of grains having different grain growth rates is reduced, and control of flux grains becomes easier. Thereby, the bulk specific gravity of the flux can be controlled within a narrow range.

[0031]

EXAMPLES The effects of the present invention will be described below with reference to examples. First, an example of improving the granulation property by the particle size of the compounding raw material used will be described. Using the fine-grained raw materials shown in Table 2 as the coarse-grained raw materials shown in Table 1, 24 types of bond fluxes shown in Table 3 were produced, and the granulating properties were evaluated.

After mixing and mixing 10 kg of the raw materials, the mixture was put into a Henschel mixer having a volume of 20 liters, and kneaded for 30 seconds while rotating two blades at 740 rotations per minute while adding water glass little by little. Check that the amount of water glass is appropriate. If insufficient, kneading is continued for 30 seconds under the same conditions while adding water glass little by little. When the amount of water glass becomes an appropriate amount repeatedly, the mixture is kneaded at 1110 rotations per minute for one minute and discharged.

About 5 kg of this kneaded raw material was used,
mm into a pan-shaped granulator, and tilt the dish backward by 40 °, 2 minutes per minute.
Rolling granulation was performed in two revolutions. The granulation time was in units of 30 seconds, and the state of granulation was visually determined. Water glass with 40 Baume 2
Molar sodium silicate was used. The flux after granulation is dried at 250 ° C. × 1 hr, and the aperture is 2.4 mm, 0.3 mm.
Sieved at 0.1 mm and 0.1 mm. Among the flux particle diameters, a flux having a particle size of more than 2.4 mm exceeds 10%, a flux having a particle size of 2.4 to 0.3 mm is less than 60%, and a flux having a particle size of less than 0.1 mm exceeds 15%. Is bad. The results are shown in Table 3 and FIG.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

Among the fluxes, A-1 to A-10 are examples of the present invention, and all have good fluxes. In addition, A-11 to A-24 are comparative examples, and no good flux was obtained in any case. That is, A-1
In Nos. 1 and A-12, the proportion of the coarse-grained raw material A was too small and the ratio of the fine-grained raw material B was too large, so that 2.4 to 0.3 mm of the flux particles were too small and 0.1 mm The following particles were in excess. In the case of A-13, the proportion of the coarse-grained raw material A was too small, so that 2.4 to 0.3 mm of the flux particles were too small and 0.1 mm or less of the flux particles were too large.

A-14, A-15, A-16 and A-
In No. 17, since the proportion of the fine-grained raw material B was too small, 2.4 to 0.3 mm of the flux particles were too small. A-
In Nos. 18 to A-23, the ratio of the coarse material A was too large, and thus, the particles of the flux exceeding 2.4 mm among the particles of the flux were excessive.
Since A-24 has a raw material having a diameter of more than 1.4 mm, an excess of particles having a diameter of more than 2.4 mm among the particles of the flux was used.

Next, in the compounding material used in the same manner,
An example in which a flux is produced by rolling granulation by combining a coarse-grained raw material and a fine-grained raw material and welded, and the welding workability and the penetration depth are shown. Fourteen types of bond fluxes shown in Table 4 were produced using the fine-grained raw materials shown in Table 2 as the coarse-grained raw materials shown in Table 1.

[0040]

[Table 4]

The mixture was kneaded with a Henschel mixer and produced by tumbling granulation using a dish granulator. The binder has 40 Baume 2
Molar sodium silicate was used. The same process as the flux in Table 3 was performed until the flux was dried.
Baking was performed at 0 ° C. × 1 hr. Using this flux, a welding workability test was performed by two-electrode, one-run, one-layer large heat input welding using a square joint.

The test specimen was JIS G3106 SM490.
3, the thick steel plates 1 and 2 have a thickness of 60 mm, the angle of the groove 4 is 30 degrees and the root face 5 is 2 as shown in FIG.
The metal 3 was integrated by temporary tack welding with a V groove of mm, and the welding conditions shown in Table 5 were used. Table 6 and FIG. 4 show the results of the welding workability test and the penetration depth measured from three macros taken from the weld bead. B1 to B8 in Table 6 are:
Good results were obtained by the effects of the present invention. On the other hand, B9 to B14, which are outside the scope of the present invention, could not obtain good results.

[0043]

[Table 5]

[0044]

[Table 6]

[0045]

By using the flux of the present invention, in submerged arc welding of a thick plate, a stable weld having a large penetration depth, excellent large heat input welding workability, and a sound weld without welding defects can be obtained. I can do it. Furthermore, by using the production method of the present invention, a bond flux having a stable grain size configuration and a bulk specific gravity can be obtained, and thus, in submerged arc welding of a thick plate, the penetration depth is stable and large, and large heat input welding workability is obtained. And a sound weld having no welding defects can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing the effect of the bulk specific gravity of a bond flux on penetration depth.

FIG. 2 is a diagram showing the effect of the blending ratio of coarse-grained raw material and the blending ratio of fine-grained raw material on the particle size composition of bond flux in the production of bond flux.

FIG. 3 is a diagram showing a groove shape having a plate thickness of 60 mm used in an example.

FIG. 4 is a diagram showing the influence of the bulk specific gravity of bond flux on penetration depth and welding workability.

[Explanation of symbols]

 1: Steel plate 3: Steel plate 4: Groove 5: Root face

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Noriyuki Ohhama 3-5-4 Tsukiji, Chuo-ku, Tokyo Nippon Steel Welding Industry Co., Ltd.

Claims (2)

[Claims] 1. In a bond flux for submerged arc welding, 60% or more of coarse particles having a flux particle diameter of 0.3 to 2.4 mm and fine particles having a flux particle diameter of 0.10 mm or less are contained in the total weight% of the flux. A bond flux for submerged arc welding, wherein the flux is 15% or less and the bulk specific gravity of the flux is 1.15 to 1.45. 2. A method for producing a bond flux for submerged arc welding, wherein a compounding material for the flux is divided into a coarse material and a fine material, and the particle diameter of the coarse material A is set to 0.
25-1.4 mm, fine-grained raw material B: 0.1 mm or less, and the mixing ratio of coarse-grained raw material A and fine-grained raw material B is 1.5 ≦ B / A ≦
8.5, and the mixing ratio of the coarse-grained raw material A is 7 to 33%.
A method for producing a bond flux for submerged arc welding, characterized by adding a binder to all the blended raw materials to perform rolling granulation.