JP3336244B2 - High temperature firing type flux for submerged arc welding and method for producing the same - 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-temperature sintering type flux for submerged arc welding and a method for producing the same, and more particularly to a high-speed fillet joint welding of a weldable H-type member used for a steel beam for a building. In submerged arc welding and the like, it is intended to advantageously improve the pock mark resistance as well as excellent welding workability in which a defect-free weld can be stably obtained.

[0002]

2. Description of the Related Art There are three types of fluxes for submerged arc welding (submerged arc welding), a molten flux, a fired flux (including a sintered flux, the same applies hereinafter), and a raw material mixed flux, depending on the manufacturing method. The main components are silicon oxide (SiO ₂ ), manganese oxide (MnO, Mn ₃ O ₄ etc.), calcium oxide (CaO)
, Alumina (Al ₂ O ₃ ) and other oxides, fluorides and the like.

[0003] Among them, the calcination type flux is generally produced by adding sodium silicate or the like as a binder to raw material powders such as oxides and fluorides, and kneading, granulating, drying and firing. Therefore, there is an advantage that it can be manufactured with relatively simple equipment and is inexpensive as compared with a molten flux. In addition, there is an advantage that a deoxidizing agent or an alloy element can be added, a weld metal component can be adjusted, and segregation of raw materials does not occur as compared with a mixed flux.

[0004] However, the quality of the flux and thus the characteristics of the welded portion vary greatly depending on the raw material. For example,
Weld defects, such as pits and pock marks, occur in the weld. These welding defects are caused by CO, CO ₂ generated at the time of welding due to moisture such as water of crystallization in the raw material or raw material oxide serving as an oxygen source.
It is generated due to gas.

[0005] In order to solve the above-mentioned problem, in a low-temperature firing type flux which is fired at a low temperature (700 ° C. or less), welding defect resistance has been improved by adding a carbonate or a deoxidizing agent to the flux. . On the other hand, high temperature (700-1000 ℃)
The high-temperature sintering flux, which is fired in JIS, can achieve low hydrogenation of the deposited metal without using a carbonate, and thus has excellent high-speed weldability, but the types of deoxidizers that can be used are very limited. And poor pock mark resistance. Moreover, at present, there is almost no examination.

As an example of adding a metal powder for the purpose of deoxidation, examples of Fe-Si and Si-Mn are described in JP-B Nos. 32-409 and 44-13249. In the high-temperature sintering type flux, the deoxidizing agent is often degraded (oxidized or nitrided) at the time of high-temperature sintering and the effect of the deoxidizing agent cannot be obtained. The kind is main. However, this Fe-
Even when Si and Si-Mn are used as the deoxidizing agent, the deoxidizing agent may be deteriorated by high-temperature sintering conditions, etc., and stable and good pock mark resistance and excellent welding workability can be obtained when the flux is used repeatedly. Had problems such as not being able to obtain.

[0007] Other, in JP-A-60 -196289, as a high-temperature sintering type flux, apart from the Fe-Si and Si-Mn,
It is described that metal powders such as Al, Mg, Ti and Ca are used as a deoxidizing agent or alloying agent. However, this technique uses a so-called mixed type in which these metal powders are added to and mixed with a base flux after firing. Therefore, the non-uniformity, which is a disadvantage peculiar to the mixed type, that the segregation of the flux material easily occurs when the flux material is sprayed on the welding portion, is not solved.

[0008]

SUMMARY OF THE INVENTION The present invention advantageously solves the above-mentioned problems, and comprises Fe-Fe used as a deoxidizing agent.
By precisely controlling the dispersion state of Si flux particles, we can effectively prevent the occurrence of welding defects such as pock marks, and thus have high efficiency and excellent welding workability, and have good pock resistance. It is an object of the present invention to propose a high-temperature sintering type flux for submerged arc welding, which can obtain the property, together with its advantageous production method.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the gas generated during welding for the purpose of improving the pock mark resistance of the high-temperature firing type flux. It has been found that it is extremely effective to effectively add Fe-Si as an agent to the flux. Therefore, the inventors further studied various methods of adding Fe-Si to the high-temperature firing type flux. As a result, when an appropriate amount of Fe-Si having a specific component and particle size distribution was added, generation of gas during welding was performed. That the pock mark resistance can be effectively improved by appropriately controlling the pock mark resistance.
The present invention is based on the above findings.

That is, the gist of the present invention is as follows. 1. This is a high-temperature firing type flux for submerged arc welding in which flux material powder is granulated and then fired at a temperature of 700 ° C or more , including flux particles with a particle diameter of 500 μm or more.
The ratio of Fe-Si particles having a particle size of 10 to 106 μm with respect to the flux particles is as follows:
A high-temperature sintering type flux for submerged arc welding, characterized in that the volume ratio is 0.5 to 20.0% per flux particle.

2. 2. The high-temperature sintering flux for submerged arc welding according to 1 above, wherein the ratio of Fe-Si particles having a particle size exceeding 106 μm to all Fe-Si particles is 2% or less by volume ratio.

3. In the above 1 or 2, a high-temperature firing type flux for submerged arc welding, wherein a weight ratio of flux particles having a particle diameter of 500 μm or more to all flux particles is 70% or more.

4. In the above 1, 2 or 3, the flux component is 30 to 70% by weight of total SiO ₂ and manganese oxide (M
In nO terms): 5~40wt%, MgO: 3~30wt %, Al 2 O 3:
A high-temperature firing type flux for submerged arc welding, characterized in that the composition contains _{2 to 20} wt%, CaO: 10 wt% or less, and CaF2: 15 wt% or less.

5. Si: 30 to 80 wt%, and particle size:
Fe-Si particles having a particle size distribution of more than 106 μm in a weight ratio of 10% or less and a particle size of less than 45 μm in a weight ratio of 50% or less,
5. The flux for submerged arc welding according to any one of 1 to 4 above , wherein a flux raw material blended at a ratio of 1 to 8 wt% as a deoxidizing agent is granulated and fired at a temperature of 700 ° C. or more. A method for producing a high temperature firing type flux.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. First, the circumstances that led to the invention will be described based on experimental results. First, the relationship between the number of generated pock marks and the particle size of the deoxidizer was investigated. The flux raw material having the composition shown in Table 1 was granulated to 12 to 100 mesh using sodium silicate as a binder, and fired at 750 ° C. for 1 hour. In Table 1, Fe-76% Si having variously adjusted particle size distribution was used as ferrosilicon. Using these fluxes and a 2% Mn-based wire (4.8 mmφ), welding current: 900
A, under a welding condition of a welding voltage of 40 V and a welding speed of 60 cm / min, a downward fillet single welding was performed on a steel plate equivalent to SS400, and the occurrence of pock marks was investigated. Table 2 shows the obtained results. As is clear from Table 2, the effect of the particle size composition of the deoxidizing agent on the number of generated pock marks is extremely large.

[0016]

[Table 1]

[0017]

[Table 2]

Next, the relationship between the occurrence of pock marks when the flux was repeatedly used and the state of dispersion of the deoxidizing agent in the flux particles was examined. as a result,
It became clear that the dispersion state of Fe-Si in the flux particles was extremely important. Table 3 shows the results of an investigation on the relationship between the volume ratio of Fe—Si particles in the flux particles and the number of pockmarks generated when the flux was repeatedly used.

[0019]

[Table 3]

In the same table, Fe-Si in flux particles
The volume ratio of the particles is measured for flux particles having a particle diameter of 500 μm or more. Further, these flux particles were used by further sieving the ferrosilicon shown in No. 1 in Table 2 and using Fe-silicon in the flux particles.
The dispersion state of Si was changed. The flux was prepared using sodium silicate as a binder, sized to 12 to 100 mesh, and fired at 850 ° C for 10 minutes. Table 3
As is clear from the above, the effect of the volume ratio of the Fe—Si particles in the flux particles on the number of pock marks generated when the flux is repeatedly used is extremely large.

As described above, in order to suppress the generation of the pock mark, the amount of Fe-Si, which is a deoxidizing agent added to the flux, the composition of the Fe-Si, and the particle size composition are not limited. It has been found that the state of dispersion in the particles is particularly important, and it is important to satisfy the following requirements.

In a flux particle having a particle diameter of 500 μm or more, the particle diameter of the flux particle: 10 to 106
Ratio of Fe-Si particles of μm: 0.5 to 20.0% per flux particle by volume ratio In flux particles having a particle diameter of 500 μm or more,
The proportion occupied by the Fe-Si particles in the flux particles,
If the volume ratio is less than 0.5% per flux particle, when the flux is used repeatedly, the effect of suppressing generated gas during welding is small, and a pock mark is generated on the weld bead. On the other hand, if it exceeds 20.0%, Fe in the flux
-Since the addition amount of Si increases, the iron content in the flux increases accordingly, which causes deterioration of the weld bead surface properties. Therefore, according to the present invention, the particle size of the flux particles having a particle size of 500 μm or more: 10 to 106
The proportion occupied by the Fe-Si particles of μm is limited to the range of 0.5 to 20.0% (preferably 1.0 to 17.5%) per flux particle.

The reason why the particle size of the Fe-Si particles whose dispersion state with respect to the flux particles is to be controlled is limited to the range of 10 to 106 μm is that the Fe-Si particles having a particle size of less than 10 μm are altered (oxidized) during firing. This is because it is difficult to stably disperse the flux in the flux particles, so that the effect on the deoxidizing effect is small. On the other hand, for Fe-Si particles exceeding 106 μm, the Si in Fe-Si is contained in the deposited metal. This is because the ratio of solid solution increases, and even if dispersed in flux particles, the deoxidizing effect during welding is small.

In the flux after firing, if the volume ratio of Fe-Si particles having a particle size exceeding 106 μm exceeds 2% by volume with respect to the whole Fe-Si particles, the deoxidizing effect is reduced, and especially the flux is reduced. This tendency becomes remarkable in repeated use of, and a pock mark easily appears.
The proportion of Fe—Si particles exceeding 06 μm is preferably not more than 2% by volume. Further, the size of the flux particles for controlling the dispersion state of the Fe-Si particles is 5
The reason for limiting the flux particles to those of
Flux particles of 00 μm or more have a relatively small change in particle size when used repeatedly, and are optimal as a size to control the dispersion state of Fe-Si particles in order to obtain stable pock mark resistance during repeated use. For that reason.

Further, the particle diameter with respect to all the flux particles is
The ratio of flux particles of 500 μm or more is 70% by weight.
% Is preferable. Because this ratio is
If it is less than 70%, the pock mark resistance is degraded due to poor outgassing of the flux-filled layer sprayed on the weld.

Next, a manufacturing method according to the present invention will be described. First, when compounding the raw materials, Fe used as a deoxidizing agent
The conditions that −Si must satisfy will be described. Si content in Fe-Si: 30-80wt% When Si content exceeds 80wt%, fine Fe-Si at high temperature firing
Since the particles are oxidized and lost, the content is set to 80% by weight or less. Also, Si
If the content is less than 30 wt%, to achieve a deoxidizing effect during welding
It is necessary to add a large amount of Fe-Si, and the addition of a large amount increases the iron content in the flux, which deteriorates the surface properties of the weld bead.

Particle size composition of Fe—Si: The ratio of particles exceeding 106 μm is 10 wt% or less, and the ratio of particles less than 45 μm is
50 wt% or less Of the Fe-Si particles, the ratio of particles exceeding 106 μm is 10%.
If the content exceeds wt%, the deoxidizing effect and the deoxidizing efficiency decrease during repeated use, and a pock mark is likely to appear. Therefore, the content is limited to 10 wt% or less. On the other hand, when the proportion of particles having a particle size of less than 45 μm is 50 wt% or more, fine Fe—Si particles are oxidized and disappeared during high-temperature sintering.

Fe—Si content in the flux: 1 to
If the content of Fe-Si with respect to the entire flux is less than 1 wt%, the desired deoxidizing effect cannot be obtained. On the other hand, if the content exceeds 8 wt%, the deoxidizing effect reaches saturation. The amount was limited to the range of 1 to 8 wt%.

By using Fe-Si satisfying the above conditions, in a flux particle having a particle diameter of 500 μm or more, the ratio of the Fe-Si particle having a particle size of 10 to 106 μm to the flux particle is defined as a volume ratio of the flux particle 1 Per piece
It can be 0.5 to 20.0%. In order to make the volume ratio of Fe-Si particles having a particle size of more than 106 μm to all Fe-Si particles less than 2% by volume, it is necessary to add
The proportion of particles exceeding 06 μm may be reduced (8% or less, more preferably 5% or less). Further, the ratio of the flux particles having a particle diameter of 500 μm or more to all the flux particles can be made to be 70% or more by weight ratio by appropriately adjusting the conditions for sizing treatment after granulation.

In the present invention, if the Fe-Si particles added as a deoxidizing agent to the flux for submerged arc welding satisfy the above requirements with respect to the state of dispersion, components, particle size composition and amount added to the flux particles. A desired effect can be obtained, but other typical compositions of the sintering flux are as follows.

Total SiO ₂ : 30-70 wt% First, SiO ₂ is necessary as a slag-making agent in order to maintain good bead appearance, and particularly when the penetration of the bead end is important such as high-speed fillet welding. If the content is less than 30% by weight, good bead shape cannot be maintained, while if it is more than 70% by weight, the viscosity becomes too high and the bead appearance is not only easily disturbed, but also the slag peels off. The total SiO ₂ content is 30 ~ 70wt% because of the troubles such as deterioration of the properties
It is preferable to set the degree.

Manganese oxide (in terms of MnO): 5 to 40 wt
% As a fillet welding flux, it is necessary that the bead ends conform well even if the welding speed is increased. For this purpose, it is preferable to use a slag containing Mn oxide. However, if the added amount is less than 5 wt% in terms of MnO amount, the effect is not recognized, and if the added amount exceeds 40 wt%. As the CO reaction becomes intense in the molten pool, the appearance of the bead deteriorates. Therefore, the amount of Mn oxide is preferably set to about 5 to 40 wt%.

MgO: 3 to 30 wt% MgO is a component useful for adjusting the melting point and viscosity of the slag and ensuring the slag removability, but if it is less than 3%, a sufficient effect cannot be obtained. %, The viscosity is too low, and the melting point is too high, which tends to deteriorate the bead appearance. Therefore, the MgO content is desirably about 3 to 30% by weight.

Al ₂ O ₃ : _{2 to 20} wt% Al ₂ O ₃ is an important component in adjusting the viscosity and melting point of the slag, but if it is less than 2 wt%, the effect of its addition is poor, while it exceeds 20 wt%. In this case, the melting point is excessively increased to cause deterioration of the bead shape. Therefore, the content is desirably about 2 to 20% by weight.

CaO: 10 wt% or less CaO is a component that affects the fluidity of slag.
If it is contained in a large amount in excess of wt%, the fluidity is impaired and the bead shape is degraded, so CaO is preferably set to 10 wt% or less.

CaF ₂ : 15 wt% or less CaF ₂ is a component that improves the fluidity of slag.
If it exceeds wt%, the fluidity of the slag will increase excessively.
CaF ₂ is preferably set to 15 wt% or less.

Although the typical flux composition has been described above, other components generally used for the flux may be added. Such components include:
There are TiO ₂ , BaO, CaO, ZrO, B ₂ O ₃ , Ti and Al. For example, TiO ₂ is reduced during welding and Ti
Has the effect of improving the toughness of the weld metal.
However, if it exceeds 10% by weight, the toughness is rather deteriorated. BaO and ZrO are added to adjust the basicity and melting point of the slag. However, any addition exceeding 5 wt% deteriorates bead appearance and slag removability. Further, B ₂ O ₃ is the reduction in the weld, contributing to toughness improvement of the weld metal and transition B is in the weld metal. However, if it exceeds 4 wt%, solidification cracking of the deposited metal is promoted.

The flux raw material powder is blended so as to have the above-mentioned preferred composition, an appropriate amount of Fe-Si adjusted to the above-mentioned components and particle size composition is added, kneaded together with a binder, granulated, and then granulated. Bake. The granulation method is not particularly limited, but it is preferable to use a rolling granulator or an extrusion granulator. After granulation, it is preferable to carry out a sizing treatment such as dust removal or crushing of coarse particles to obtain particles having a particle diameter of 0.075 to 2.5 mm. In addition, as the binding agent (binder), an aqueous solution such as polyvinyl alcohol or water glass is preferable. Among them, conventionally used sodium silicate having a molar ratio of SiO ₂ to Na ₂ O of 1 to 5 is advantageously suited. The amount used may be about 80 to 150 cc per kg of raw material. If the firing temperature is lower than 700 ° C, the moisture introduced from the binder will not be sufficiently dried and the diffusible hydrogen in the deposited metal will increase, so the firing temperature must be 700 ° C or higher. is there.

The ratio of the Fe-Si particles to the flux particles and the total Fe of the Fe-Si particles exceeding 106 μm
-Calculation of the ratio to the Si particles was performed by observing the flux cross section. For observation, either an optical microscope or an electron microscope may be used.
Performed at 10-100 times. The test piece was prepared by embedding a flux in a resin or the like and polishing it. Flux particles and
The volume of the Fe-Si particles was calculated from the observed image by calculating the area of the flux particles and the Fe-Si particles using an image analysis processor, calculating the diameter of a circle having an equivalent area, and using the value. The measurement was performed on more than 20 randomly selected flux grains. The Fe-Si particles in the other raw material particles can be easily identified by an energy dispersive X-ray analyzer or the like.

Here, the particle diameter and the particle diameter represent the diameter of each particle. The ratio of flux particles with a particle diameter of 500 μm or more is determined using a sieve that conforms to JIS Z 8801.
It was determined by measuring the particle size distribution according to the rules of 2601.

[0041]

Example 1 Welding slag (pulverized to 250 μm or less) having the composition shown in Table 4 was added to a flux raw material adjusted to a predetermined component composition.
30 wt% was added, and kneading, granulation, drying, firing and particle size adjustment were performed according to a conventional method to obtain a flux having a component composition shown in Table 5. The amount of Fe-Si exceeding 106 μm was 10 wt.
% Or less, and those having a particle size distribution of less than 45 μm have a particle size distribution of 50 wt% or less, and those having a Si content of 18 to 76 wt% were used. The firing conditions are
The temperature was 875 ° C for 10 minutes. Using these fluxes and a 2% Mn-based wire (4.0 mmφ), welding current: 850 A, welding voltage: 40 V, welding speed: 50 cm / min, SM400
Downward fillet welding was performed on a considerable steel plate, and the appearance of the bead was investigated. Table 6 shows the observation results of the bead appearance.

[0042]

[Table 4]

[0043]

[Table 5]

[0044]

[Table 6]

As is clear from Table 6, the components of Fe—Si
When a flux of a suitable example in which the amount of addition and the state of dispersion in the flux particles satisfy the appropriate range of the present invention was used, a good beat appearance could be obtained. On the other hand, Comparative Example 1 in which the Si content in Fe-Si was less than the appropriate range
In each of Comparative Examples 3 and in which the amount of Fe—Si added was too small, the number of occurrences of pock marks was much larger than that of the inventive examples. In Comparative Example 2 in which the amount of Fe-Si added was too large, the number of occurrences of pock marks was small, but the bead surface properties were significantly inferior. Decreased.

Example 2 6 wt% of Fe-46% Si having variously changed particle size distribution was added to the same flux raw material as in Example 1, and a high temperature firing type flux was produced in the same manner as in Example 1. . Then, Table 7 shows the results of an investigation on bead appearance when downward fillet welding was performed under the same conditions as in Example 1 using these fluxes.

[0047]

[Table 7]

As is clear from Table 7, when a flux satisfying the requirements of the present invention was used, a good bead appearance could be obtained.

[0049]

Thus, according to the present invention, even during high-speed welding, the generation of gas is effectively suppressed, and the submerged arc welding not only has excellent pock mark resistance but also has good welding workability. High-temperature sintering type flux can be obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kaname Nishio 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Corporation Chiba Works (56) References JP-A-4-313490 (JP, A) JP-A Sho JP-A-6-277878 (JP, A) JP-A 1-233095 (JP, A) JP-A-3-57493 (JP, U) JP-B-47-8123 (JP, A) B1) JP-B 37-2160 (JP, B1) JP-B 49-20709 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 35/362 B23K 35/40

Claims (5)

(57) [Claims] A high-temperature sintering type flux for submerged arc welding obtained by granulating a flux raw material powder and firing at a temperature of 700 ° C. or more, comprising flux particles having a particle diameter of 500 μm or more.
For box particle, the particle size for the flux grains: 10
A high-temperature sintering flux for submerged arc welding, wherein the proportion of Fe-Si particles of up to 106 µm is 0.5 to 20.0% per flux particle by volume ratio. 2. The high-temperature firing type flux for submerged arc welding according to claim 1, wherein the proportion of Fe-Si particles having a particle size of more than 106 μm to all Fe-Si particles is 2% or less by volume. 3. The high-temperature firing type flux for submerged arc welding according to claim 1, wherein the weight ratio of the flux particles having a particle diameter of 500 μm or more to all the flux particles is 70% or more. 4. The method according to claim 1, wherein the flux component is: total SiO ₂ : 30 to 70 wt%, manganese oxide (in terms of MnO): 5 to 40 wt%, MgO: 3 to 30 wt%, Al ₂ O ₃ : A high-temperature firing type flux for submerged arc welding, characterized in that it has a composition containing _{2 to} 20% by weight, CaO: 10% by weight or less, and CaF2: 15% by weight or less. 5. Si: contains 30 to 80% by weight and has a particle size of 10
A flux material containing Fe-Si particles having a particle size distribution of more than 6 μm in a weight ratio of 10% or less and a particle size of less than 45 μm in a weight ratio of 50% or less as a deoxidizing agent in a ratio of 1 to 8% by weight. The method for producing a high-temperature sintering type flux for submerged arc welding according to any one of claims 1 to 4 , wherein the sintering is performed at a temperature of 700C or more after granulation.