JPH09216090A - Non-low hydrogen covered electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-low hydrogen covered electrode in which various conventional performance can be secured by adjusting the composition of the coating flux, and the spatter can be reduced even when high current is used by providing the arc of extremely excellent stability. SOLUTION: In a non-low hydrogen covered electrode, the coating flux having a composition consisting of, by weight, 5-22% lime carbonate, 13-35% rutile, 11-24% silica sand, 1.9-8.7% Fe-Mn, 15-43% iron powder, 1.5-7.3% organic matters, 0.2-1.6% the total of one or two kinds of barium carbonate and strontium carbonate, the arc stabilizer, the slag generating agent, the fixing agent, and inevitable impurities is coated on the steel core wire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding material used for structures such as shipbuilding, construction and bridges.
〜570N / mm ² steel target non-low hydrogen system coated arc welding rod (hereinafter referred to as non-low hydrogen system rod) which can improve arc stability, reduce spatter scattering, and secure sound weld metal It is about.

[0002]

2. Description of the Related Art Non-low hydrogen type rods have better welding workability and bead shape than low hydrogen type coated arc welding rods.
It is well known that it is a versatile welding rod applied to steel materials of a wide range of structures. However, non-low hydrogen type rods are often used under severe welding conditions,
At present, it is used at high current for the purpose of improving work efficiency. In this welding work, the arc force becomes excessively strong and deep penetration into the work piece can be obtained, but on the other hand, the scattering of spatter increases and it takes time and effort to remove the spatter adhering to the steel plate. There were problems such as the possibility of burning flammable materials.

Therefore, there is a strong demand for reducing the amount of spatter in non-low hydrogen type rods.
No. 0-36878, a large amount of T is contained in the coating agent.
comprises iO _2, and intended to attempt is made to decrease in sputtering by limiting the Mn reduce the C in the steel core wire, the welding rod by its object Joule heat when it considerably be achieved using a high current There was a problem that the coating material deteriorated due to red heat, so-called stick burning phenomenon, and a healthy weld metal could not be obtained.

On the other hand, in Japanese Patent Publication No. 7-106469, an artificial wollastonite and a natural wollastonite are used in a coating agent to ensure productivity and reduce spatter. The publication relates to low-hydrogen rods, and even if this method is applied to non-low-hydrogen rods, almost no effect is found, and there is a problem that the bead shape is deteriorated due to the reduction of the arc force and the insufficient spread of the arc. Became.

As described above, it was very difficult to obtain a good arc state and reduce spatter while satisfying various performances in the current non-low hydrogen type rod. The industry that uses welding rods strongly demands welding rods with low spatter from the viewpoint of work efficiency and the risk of fire, and in accordance with this, good welding workability and sound weld metal without defects can be secured. There has been a demand for a non-low hydrogen type rod capable of satisfying all of these.

[0006]

In view of such circumstances, the present invention examines the coating composition to secure the various performances of the prior art, and at the same time, makes the stability of the arc extremely good, thereby using a high current. Even so, it is an object of the present invention to provide a non-low hydrogen type rod capable of reducing spatter.

[0007]

As a result of various studies to achieve such an object, the present invention provides a welding rod coating material having good arc stability and capable of significantly reducing spatter generation. developed. That is, the gist of the present invention is: lime carbonate; 5 to 22% by weight (hereinafter referred to as%), rutile; 13 to 35%, silica sand; 11 to 24%, Fe-M
n; 1.9 to 8.7%, iron powder; 15 to 43%, organic matter;
1.5 to 7.3%, the total of one or two of barium carbonate and strontium carbonate (hereinafter represented by a trace amount of carbonate); 0.2 to 1.6%, and an arc stabilizer and a slag generator. A non-low-hydrogen coated arc welding rod, characterized in that it is applied to a steel core wire by using a coating material consisting of a sticking agent and unavoidable impurities.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have earnestly studied means for reducing spatter even when using a high current and having a good arc state while satisfying various performances. It is known that the cause of spatter is, for example, an excessively strong plasma flow or arc force at the time of arc generation, or gas explosion of droplets. In particular, the coarsened droplets are ruptured by the pressure of the internal gas and become large-sized spatters, and the fluctuation of the arc voltage increases and the stability of the arc deteriorates. Therefore, in order to reduce the spatter, focusing on the fact that it is extremely effective to maintain an appropriate arc force and atomize the droplets, the research of various coating material was accumulated.

As a result, it has been found that barium carbonate and strontium carbonate as the trace carbonates have an extremely large effect of reducing spatter and do not adversely affect various welding performances.
These carbonates have a low ionization voltage compared to lime carbonate, which is used as a main raw material for non-low hydrogen type rods, and thus the arc is stable, and even if welding is performed using a high current, coarsening suitable for melting is reduced. Since it can be suppressed, the spatter can be reduced.

If the trace amount of carbonate in the present invention is used in a large amount, the arc force is weakened, so that slag entrainment or fusion failure occurs and the deterioration of X-ray performance becomes a problem, and further slag releasability and bead shape are deteriorated, which causes welding. Since the workability deteriorates, finding the appropriate content was important for completing the present invention.

First, the following experiment was conducted in order to investigate the proper content of a trace amount of carbonate in the coating material. That is, the content of a trace amount of carbonate was changed from 0 to 3.5% with respect to the coating agent for non-low hydrogen type rods shown in Table 1, and this was measured according to JIS G 3523 SWY11 having a diameter of 4.0 mm and a length of 450 mm. We coated and dried the steel core wire to make a welding rod, and investigated various welding performances using an AC welding machine.

[0012]

[Table 1]

For the investigation of the amount of spatter generated, a copper collecting box having a width of 200 mm, a length of 600 mm and a height of 200 mm was prepared, and a slit having a width of 40 mm and a length of 550 mm was provided on the opening / closing plate above the inside of the collecting box. Thickness 20mm, width 50mm, length 450mm
The mild steel plate of No. 3 was stood and a welding rod was inserted into the slit to weld the thick plate surface and collect spatter. The welding conditions were an AC welder with a current of 200 A and a welding speed of 200 mm / min, and the criteria for judgment were less than 1.3 g / min.
g / min was markedly inferior to Δ, and 2.2 g / min or more was inferior to x.

In the investigation of welding workability, a plate thickness of 12 mm and a width of 1
A mild steel plate with a length of 00 mm and a length of 500 mm is assembled into a T-shape, an AC welding machine is used, and the horizontal fillet has an electric current of 200 A and a vertical fillet of 150.
Using A, the arc state, slag state, bead shape, etc. were investigated. The judgment is a comprehensive judgment of each welding posture,
Good ◯, slightly inferior Δ, and inferior x.

In the X-ray transmission test, the plate thickness 30
mm, width 150 mm, length 400 mm using a V-groove shown in FIG. 1 in the longitudinal direction to form a groove having a length of 400 mm and a depth of 23 mm, and welding is performed in a downward position. Current 180A, welding speed 200mm / min, welding length 350mm,
The temperature between preheating passes was 100 ° C., and the temperature was raised in 20 passes.
Judgment is based on JIS Z 3104, first grade is good,
It was decided to be a little inferior to the 2nd grade and inferior to the 3rd and 4th grades.

The results obtained from the above tests are shown in FIG. When the trace amount of carbonate is less than 0.2%, the stability of the arc is poor, and thus the spattering is large, but when it is 0.2% or more, a good arc state is obtained and the spatter is reduced. If the content of a trace amount of carbonate exceeds 1.6%, the arc force will be weakened, resulting in poor familiarity with the welding base metal and a convex bead in both horizontal fillet and vertical postures, and poor slag removability. Welding workability deteriorated overall. Further, when the content is 2.4% or more, the arc force becomes extremely weak and slag entrainment and welding defects such as poor fusion occur and the X-ray performance deteriorates. From the above, it was found that the content of the trace amount carbonate in the coating material should be 0.2 to 1.6% in order to reduce spatter while ensuring good welding performance.

The action of each coating component in the present invention and the reason for limiting the component range will be described below. Calcium carbonate Add 5 to 22% of lime carbonate to the coating agent, because lime carbonate decomposes in the arc and generates CO ₂ gas, so weld metal and molten slag are cut off from the atmosphere, and nitrogen and oxygen intrude. This is to prevent the arc, secure the arc force, and adjust the fluidity and viscosity of the slag. If the amount added is less than 5%,
The fluidity of the slag and the slag removability deteriorate. On the other hand, 22
If it exceeds%, the encapsulating property of the slag is deteriorated and the beads have a convex shape.

Rutile: 13-35% Rutile acts as a slag forming agent and viscosity modifier, enhances slag encapsulation, and is also effective as an arc stabilizer. If it is less than 13%, the stability of the arc deteriorates, the scattering of spatter increases, and the slag encapsulation deteriorates, so that the bead shape also deteriorates. On the other hand, when it exceeds 35%, the arc force becomes weak, and when welding is performed using a high current, the welding rod becomes red hot, the coating material deteriorates, and the viscosity of the slag becomes high, and the fluidity of the slag is poor in the vertical position. The bead has a convex shape.

Quartz sand; 11-24% Quartz sand acts as a refractory agent and slag modifier.
If it is less than%, the slag encapsulation is poor and the slag releasability is also deteriorated. If it exceeds 24%, the coated cylinder becomes too deep, the arc state deteriorates, and the bead waveform also deteriorates.

Fe-Mn: 1.9 to 8.7% In the present invention, Fe-Mn has the functions of welding workability and an alloying agent. If it is less than 1.9%, the fluidity of the slag is deteriorated, the waveform of the bead is disturbed, the bead appearance is deteriorated, and it does not act as an alloying agent. If it exceeds 8.7%, the viscosity of the slag decreases, and the weld metal drops in vertical or upward welding to form a convex bead.

Iron powder: 15 to 43% Iron powder is added in order to improve electric conductivity, improve arc re-generation, increase the amount of deposition, and improve welding work efficiency. If it is less than 15%, it is extremely difficult to regenerate the arc. If it exceeds 43%, the sheath becomes shallow, the arc is unstable and short-circuiting is likely to occur, and the electric conductivity of the sheath is excessively improved, and arc occurs even in other than the sheath, which is not preferable for safety.

Organic matter: 1.5 to 7.3% Organic matter greatly contributes to carbonization of the tip of the coated cylinder during welding and good regeneration of arc with iron powder.
It is added to moderate the spray strength of the arc. 1.
If it is less than 5%, it is difficult to regenerate the arc, the arc is insufficiently sprayed, sufficient penetration cannot be obtained, and welding defects such as slag entrainment easily occur. If it exceeds 7.3%, the re-generation of the arc will be good, but the blowing of the arc will be strong, undercut will be likely to occur, and the molten metal will drip in the vertical position, and if high current is used, coating will occur. The agent deteriorates and stick burning occurs, and a healthy weld metal cannot be obtained.

Trace carbonate: 0.2 to 1.6% Barium carbonate and strontium carbonate represented as trace carbonates in the present invention are the most important parts in the present invention. These are one kind or two kinds. If the total is less than 0.2%, the arc is not stable and droplets cannot be atomized, so that spatter is often scattered. On the other hand, if it exceeds 1.6%, the arc force becomes weak and a convex bead shape is formed, so that the slag removability deteriorates and the welding workability deteriorates. If it is 2.4% or more, the arc force will be further weakened, and slag entrainment, fusion failure, etc. will occur and X-ray performance will deteriorate.

The arc stabilizer, the slag forming agent, the fixing agent and the unavoidable impurities in the coating material used in the present invention are as follows. (1) Arc stabilizer The arc stabilizer is feldspar, wollastonite, etc., and these can be used in one kind or in a combination of two kinds, and the proper content thereof is preferably 0.2 to 3.5%. (2) Slag-forming agent The slag-forming agent is alumina, illuminite, magnesium oxide or the like, which can be used in one kind or in a combination of two or more kinds, and the total amount thereof is preferably 0.5 to 4.5%. (3) Adhesives Adhesives are potassium silicate and sodium silicate,
These can be used alone or in combination of two kinds, respectively, and the solid mass of one kind or a total of two kinds is from 3.5 to 3.5 in the coating material.
It is preferably used in the range of 8.5%. (4) Inevitable Impurities Inevitable impurities are C, P, S, Cl and the like, and it is preferable that the total of one or more of these is 0.5% or less.

The steel core wire used in the present invention means that the steel core wire contains 0.01 to 0.14% C, 0.05% or less Si, and 0.2 to 1.0% Mn. , P is 0.03% or less, S
Is preferably 0.03% or less.

[0026]

EXAMPLE A coating material having the structure shown in Table 2 was coated on a core wire of JIS G 3523 SWY11 having a diameter of 4.0 mm and a length of 450 mm, and then dried to prepare 30 kinds of test welding rods, and an alternating current Using a welding machine, the amount of spatter generated, the welding workability and the X-ray transmission test were conducted by the welding, the measurement conditions, and the same evaluation method, which were carried out to investigate the effect of the addition of the trace amount of carbonate. When the results of each investigation under these test conditions and the comprehensive judgment were made, the results shown in Table 2 were obtained.

In Table 2, welding rods No. 1 to No. 1
No. 5 is an example of the present invention, and Nos. 16 to 30 are comparative examples. No. 1 to No. 15 of the non-low system rod of the present invention have individual components satisfying the requirements of the present invention and a trace amount of carbonate of 0.2.
Since the content is up to 6%, the arc is stable, the generation of spatter is extremely small, and the workability and X-ray performance are excellent.

Comparative examples No. 16, No. 21 and No. 30 are
Since the content of the trace amount of carbonate is excessively high, the stability of the arc is extremely good and the spatter is small. However, the arc force is too weak, and the workability is poor and the workability is deteriorated. In addition, the X-ray performance was deteriorated due to poor fusion and slag inclusion. In No. 16, since the amount of lime carbonate was large, the arc was unstable and the bead shape was poor, and since the amount of silica sand and Fe-Mn was small, the slag state deteriorated, and the welding workability also deteriorated due to this cause. Since No. 21 has a low content of lime carbonate, the amount of CO ₂ generated is reduced, the X-ray performance is slightly deteriorated due to inclusion of air, and the slag is highly viscous due to the excessive content of rutile and silica sand, and it has a bead shape. Deterioration occurred. No30
Since the content of Fe-Mn was large, the viscosity of the slag was lowered, the weld metal dripped down in the vertical direction, the bead shape was deteriorated, and the welding workability was deteriorated.

No17, No18, No20, No2
Since No. 2, No. 23, No. 27, No. 28, and No. 29 contained a trace amount of carbonate in an appropriate amount, the amount of spatter generated was small, but there was a problem that welding workability was poor as described below. First, in No. 17 and No. 18, since a large amount of iron powder is contained, the covering cylinder is shallow and the stability of the arc is deteriorated.
At o18, since the amount of organic substances was small, the arc spray was weak and the welding workability was deteriorated. Since No. 20 contains lime carbonate and an organic substance in excess, the arc force becomes excessively strong, so that the encapsulating property of the slag deteriorates, and since Fe-Mn is also large, the viscosity of the slag decreases and the bead has a convex shape. In the vertical direction, the bead shape was remarkably deteriorated. No
Since No. 22 and No. 23 contained a small amount of iron powder, it was difficult to regenerate the arc after the arc was interrupted. No. 22 had a large amount of silica sand and No. 23 had a large amount of lime carbonate, so the arc was unstable and the bead shape deteriorated. In No. 27, lime carbonate was contained in a small amount, so that the peelability of the slag was poor, and in No. 28, the coating material became red hot due to the excessive content of the organic substance, and the stick burning phenomenon occurred. In No. 29, since the iron powder was small, the re-generation of the arc became worse.

Next, No19, No24, No25, No
Regarding No. 26, the trace amount of carbonate was not contained or the content thereof was small, so that the stability of the arc was poor and the meltability was coarsened, and the amount of spatter was increased. Further, in No. 19, lime carbonate and Fe-Mn are small, and since rutile is contained in a large amount, the slag has very poor peelability and fluidity, the bead shape is deteriorated, and since there are many organic substances, undercutting occurs, and welding workability is also improved. It got pretty bad. In No24, F
Since the e-Mn and the organic substance were excessively contained, the viscosity of the slag was lowered, and the weld metal dripped vertically and the bead became a convex shape. In No. 25, since the content of silica sand and organic matter was small, arc spraying was weak, slag encapsulation was poor, and welding workability was poor. In No. 26, since the amount of rutile was small, the encapsulating property of the slag deteriorated, and along with this, the bead shape deteriorated and welding workability deteriorated.

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

[0034]

[Table 5]

[0035]

As described above, the non-low hydrogen type rod of the present invention is a welding rod capable of significantly reducing the generation of spatter by improving the arc stability and ensuring good welding performance. It can be provided and can greatly contribute to fire prevention and improvement of welding work efficiency in welding work.

[Brief description of drawings]

FIG. 1 shows the shape and dimensions of the groove used to investigate X-ray performance.

FIG. 2 is a diagram investigating the influence of the content of a trace amount of carbonate on the amount of spatter generation, welding workability, and X-ray performance.

Claims (1)

[Claims] 1. A non-low hydrogen type coated arc welding rod,
By weight%, lime carbonate; 5-22%, rutile; 13-35%, silica sand; 11-24%, Fe-Mn; 1.9-8.7%, iron powder; 15-43%, organic matter; 1 0.5 to 7.3%, one or two of barium carbonate and strontium carbonate
Total of seeds; 0.2 to 1.6%, and non-characterized in that it is applied to the steel core wire by using a coating agent composed of an arc stabilizer, a slag forming agent, a fixing agent and inevitable impurities. Low-hydrogen coated arc welding rod.