JP2614967B2 - Gas shielded arc welding metal flux cored wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flux-cored wire, and more particularly to a metal-based flux-cored wire for gas shielded arc welding with reduced fume generation. Suitable for welding.

[0002]

2. Description of the Related Art In recent years,
While labor shortages are being called out in the entire industry, the shortage of welding technicians is particularly acute.In industries such as steel frames, industrial machinery, and shipbuilding, high efficiency, automation, and robotization are being promoted.
Efforts to improve the welding work environment are rapidly advancing from the viewpoint of 3K removal.

Due to the shortage of welding technicians, the demand for flux-cored wires for gas shielded arc welding has been rapidly growing in recent years from the viewpoints of (1) ease of welding and (2) high efficiency. Among them, a metal-based flux-cored wire, in particular, has the advantage of having a small amount of slag in addition to the advantages of (1) and (2), and is expected to grow.

[0004] However, the greatest difficulty of this type of wire is that it is used at a high welding current in order to obtain high efficiency, so that a large amount of fume is generated and its extension is questioned from the viewpoint of the welding work environment. ing.

SUMMARY OF THE INVENTION [0005] In view of these requirements, an object of the present invention is to provide a gas-shielded arc-welded metal-based flux-cored wire that generates less fume.

[0006]

A technique for reducing welding fume is disclosed in Japanese Patent No. 1403569 by the present applicant.
Nos. 1572313 and 1572327, and it is known that it is particularly effective to reduce the amount of C and oxygen in the outer skin. However, in the case of a metal-based flux cored wire, it is applied at a high current (for example, 300 to 500 A) in order to obtain a high welding speed, and the amount of welding fumes increases exponentially with an increase in the current. Can not.

Therefore, the present inventor has conducted intensive studies on measures to reduce the amount of fume generated in the metal-based flux-cored wire. , Al was found to be effective, and based on this finding, the present inventors completed various tests and studies to complete the present invention.

That is, the present invention relates to a gas-shielded arc-welded metal flux-cored wire obtained by filling a mild steel outer sheath with a flux, wherein C: ≦ 0.02% Ti as a ratio of the mild steel outer sheath to the total weight of the outer sheath. : A steel containing 0.01 to 0.20% Al: 0.01 to 0.10% and having a composition satisfying Ti / C ≧ 1.0 Al / C ≧ 1.5. Ti or Ti oxide (converted to Ti amount): 0.03 to 1.0% One or more of alkali metal oxides and fluorides (converted to alkali metal element): 0.1. 01 to 0.15% Fe: 5 to 28% Metal powder: ≧ 94% (based on the total weight% of flux), and further Mn (total Mn content in the outer skin): 0.5 to 3.6% Si (sum of the amount of Si in the outer skin): Metal flux containing 0.1 to 1.8% It is a symptom.

Hereinafter, the present invention will be described in more detail.

[0010]

[Action]

First, the reason for limiting the components of the wire sheath in the present invention will be described. Various experiments were conducted to examine means for reducing welding fumes from the outer shell component surface, and examples of experimental results showing the outline of the results obtained by the experiments are described below.

In these experiments, No. 1 in Table 1 described later was used.
Of the composition (flux rate 15%) with various T
i, mild steel outer skin with Al content (C: 0.003-0.03%, Mn:
0.20 to 0.30%, Si: 0.01 to 0.03%, P:
0.008 to 0.011%, S: 0.005 to 0.007
%, N: 0.002 to 0.004%) and 1.4 mm
A flux-cored wire having a diameter was produced.

Next, downward bead-on-plate welding was performed using a test plate JIS G3106 SM490A (plate thickness: 12 mm) under the following welding conditions, and the amount of welding fumes generated during the downward welding was determined in accordance with JIS Z3930. Measured.

(Welding conditions) Welding current: 350 A Welding voltage: 36 V Welding speed: 30 cm / min Wire protrusion length: 25 mm Polarity: DC (wire plus) Shielding gas: CO ₂ , flow rate 25 liter / min

1 and 2 show welding fume generation amounts and Ti, Al, C in the outer skin based on data obtained by experiments.
It is a relation between quantity and quantity. As shown in FIGS. 1 and 2, in order to reduce the amount of welding fume generation, in addition to the conventional technique of lowering the C% for the outer shell component, Ti, Al
It was confirmed that the addition of a composite of 0.01% or more was an effective means. Of these, it was found that Al alone had little effect, and a remarkable effect was produced only when combined with Ti. The welding fume reducing effect of Ti and Al is C ≦ 0.02% and Ti / C ≧ 1.0.
0, it was also found that Al / C ≧ 1.5.

The reason why Ti and Al can reduce the welding fume is that Ti and Al have a strong affinity for oxygen and generate a high freezing point oxide. It is considered that an oxide film is formed on the surface to suppress the explosive generation of fume generation sources CO and CO ₂ generated as a result of the reaction between C and oxygen.

The upper limits of the Ti and Al contents need to be 0.20% and 0.10%, respectively, in order to avoid deterioration of the material due to reduced ductility and hardening resulting from the yield to the weld metal. Was determined.

For the above reasons, the mild steel outer skin suitable for reducing welding fume is C ≦ 0.02% Ti: 0.01 to 0.20% Al: 0.01 to 0.1% in terms of the total weight of the outer skin. It is a steel containing 10% and having a composition satisfying Ti / C ≧ 1.0 and Al / C ≧ 1.5.

A more preferable range is as follows: C: ≦ 0.01% Ti: 0.01 to 0.10% Al: 0.01 to 0.05%, and Ti / C ≧ 3.0 The composition satisfies Al / C ≧ 2.0. In consideration of the workability in the rolling and / or drawing process in wire manufacturing, Mn: 0.1.
The range of 10 to 0.70% and Si ≦ 0.35% is desirable.

Next, the reason why the flux components to be filled are limited will be described. The flux component is a percentage by weight based on the entire wire.

Ti or Ti oxide (in terms of Ti amount): 0.03 to
1.0% Ti is effective in reducing the amount of welding fume, improving penetration shape and improving arc stability, and is added in consideration of the amount of Ti in the outer skin. That is, when Ti is 0.03% or more, it is effective in reducing the amount of welding fume, improving the penetration depth and improving the arc stability. However, if the content exceeds 1.0%, in the case of Ti in the form of a metal or an alloy, the yield to the deposited metal is increased and the ductility is extremely reduced. Defects such as slag winding are likely to occur during welding.

In order to reduce the amount of welding fume generated from the surface of Ti / C ≧ 1.0 flux component, the amount of C in the flux is reduced, and at the same time, Ti is reduced.
Is effective according to the amount of C. That is, Ti
When the / C ratio is 1.0 or more, a remarkable effect of reducing welding fume can be obtained. Examples of the Ti source include alloys such as metal Ti and Fe-Ti, and oxides such as rutile, reduced illuminite, lucoxin, illuminite, and potassium titanate.

Al or Al ₂ O ₃ (in terms of Al amount): 0 to 1.0% Al is not remarkable as compared with Ti, but has an effect of reducing the amount of welding fume, and is added as necessary. In that case,
When Al exceeds 1.0%, in the case of metal or alloy Al,
The yield of Ti on the deposited metal is excessively increased, and the ductility is significantly reduced. In the case of Al ₂ O ₃ , the slag removability is significantly reduced. In addition, Al, Fe-Al, Al-Li are used as Al sources.
And oxides such as Al ₂ O ₃ .

At least one of alkali metal oxides and fluorides
(Converted to an alkali metal element): 0.01% to 0.15% Li, N
Add alkali metal components such as a, K, Rb and Cs. Since the alkali metal has remarkable hygroscopicity, it is preferable to use one or more kinds in the form of an oxide or a fluoride. The reason for limiting to the above range is that if it is less than 0.01%, the effects of improving arc stability and reducing spatter cannot be obtained, and 0.15%
Above this, because these alkali metals have a high vapor pressure, spatter increases, and in addition, the effect of reducing welding fume by Ti and Al cannot be obtained.

Incidentally, feldspar, sodium silicate anhydride, water glass,
Compound oxides such as Li, Na, and K, fluorides such as cryolite, potassium silicate, and sodium silicate, and a small amount of alkali metal carbonates are also decomposed by arc heat to form oxides. Similar effects can be obtained.

C: 0 to 0.07% C is a deoxidizing agent , in order to secure toughness by improving strength and hardenability and to obtain a penetration depth. An appropriate amount can be added to the flux. In that case, C
If the amount exceeds 0.07%, the effect of reducing the amount of welding fume by Ti and Al cannot be obtained, and the amount of generated welding fume increases significantly. Therefore, the amount is set to 0.07% or less. In addition, as a C source,
Fe-Mn, Fe-Si-Mn, graphite, iron powder (carbon steel, cast iron)
And carbonates.

Mn (sum of Mn content in the outer skin): 0.5 to
3.6% Mn also considers the amount of Mn in the outer skin to improve toughness by improving the deoxidizing agent, strength and hardenability, and to improve the bead shape by increasing the viscosity of molten metal slag (particularly for horizontal fillets) And add. In this case, if Mn is less than 0.5%, sufficient strength cannot be obtained even for mild steel, and the bead shape is not good. On the other hand, if Mn exceeds 3.6%, the strength of the deposited metal becomes excessive and low-temperature cracking easily occurs. The Mn source includes Mn, Fe-Mn, Fe-Si-Mn, and the like.

Si (total amount of Si in the outer skin): 0.1 to
1.8% Si has the same effect as Mn. However, when Si is 0.
If it is less than 1%, the effect of deoxidizing agent, improvement of toughness and bead shape cannot be obtained, and if Si exceeds 1.8%, the amount of Si in the deposited metal becomes excessive and toughness and ductility decrease. ,
Within the above range. The source of Si is Si or Fe-S
i, Fe-Si-Mn, Fe-Si-Mg and the like.

Fe: 5-28% The amount of Fe powder is added according to the flux rate in order to obtain a high welding speed. If the flux rate (flux to total wire weight%) is less than 10%, the thickness of the shell metal is too large, and the spatter of large grains increases. On the other hand, if it exceeds 30%, the wire becomes softer as the thickness of the skin metal decreases,
In addition to lowering the feedability, the spread of the arc becomes remarkable, so that the penetration depth and the undercut tend to occur. Therefore, the flux rate is preferably in the range of 10 to 30%.

Fe powder is added in accordance with the above-mentioned flux rate. However, if it is less than 5%, a remarkable high welding speed characteristic of a metal-based flux-cored wire cannot be obtained and 28%
If it is too large, other components such as a deoxidizing agent will be insufficient, and it will be difficult to secure the mechanical properties of a predetermined weld metal and prevent welding defects such as pits and blow holes. Therefore, the amount of Fe powder is 5-28%
Range.

Metal powder: ≧ 94% ( based on the total weight of flux) Oxides, fluorides, and carbonates to ensure high welding speed characteristics and the amount of slag capable of continuous multilayer welding, which are the characteristics of metal-based flux cored wires. It is necessary to make the ratio of metal powder in the flux excluding non-metallic substances such as the above 94% or more.

In order to further improve the bead appearance and shape within a range satisfying the above metal powder ratio, SiO ₂ ,
In order to add oxides such as ZrO ₂ , CaO, and FeO, and to improve slag removability, a range of 0.1% in which hot cracking does not occur.
% (Total wire weight%) or less of bismuth oxide (Bi ₂ O ₃ ) or MgO or Mg of 0.2% (total wire weight%) or less within a range where the bead shape does not deteriorate. Can also.

Further, the base material steels to which the present invention is applied are mainly mild steels and high tensile steels. Depending on the application, metals or alloys such as Ni, Cr, Mo and Cu are added to obtain low alloy steels and high alloy steels. Enlargement can be applied.

The type of the shielding gas is mainly carbon dioxide gas, but may be Ar, He, or the like, or may be a mixed gas thereof. Also, there is no limitation on the cross-sectional shape of the flux-cored wire. For example, FIG.
Various shapes illustrated in (B), (C) and (D) can be used. In the case of the shape (D), the surface of the wire may be plated with Al, Cu, or the like, and the plating amount is 0.05 to 0.3.
0% is appropriate. The wire diameter is 1.2mm according to the application.
φ, 1.4mmφ, 1.6mmφ, 2.0mmφ, 2.4mmφ,
It can be arbitrarily determined from 3.2 mmφ.

Next, examples of the present invention will be described.

[0036]

【Example】

Using a shell metal made of steel having the composition shown in Table 1, a filling flux having the component composition shown in Tables 2 and 3 was prepared, and the test wire (A) in FIG. (The wire diameter was 1.4 mmφ). Next, welding was performed using the flux-cored wires under the following conditions, and the fume generation amount, workability, and the like were investigated.

(Welding conditions) Polarity: DC wire (+) Welding current: 350 A Voltage: 37 ± 3 V Speed: 30 cm / min Shielding gas: 100% CO ₂ , 25 l / min Distance between tip base materials: 25 mm Test plate: JIS G 3106, SM490A (12 mmt) Welding method: Downward bead-on-plate welding

(Fume measuring method) According to JIS Z 3930 “Method of measuring total fume amount of coated arc welding rod”, 1
The weight per unit time (g / min) (the number of repetitions =
3 average value). The fume was collected by a device equipped with a collection box shown in FIG.

The experimental results are shown in Table 4 and are considered as follows.

Experiments Nos. 1 to 8 are examples of the present invention, in which the amount of generated fume is extremely small. On the other hand, since the comparative examples of Experiment Nos. 9 to 31 do not completely satisfy the requirements of the present invention, the workability and the like are inferior even when the fume generation amount is large or relatively small as shown below. I have.

Experiment No. 9 is an example in which the C content of the outer skin metal is out of the range of the present invention, and the amount of generated fume is increased.

Experiments Nos. 10 to 11 are examples in which the Ti content of the outer metal is out of the range of the present invention. descend.

Experiments Nos. 12 and 13 are examples in which the Al content of the shell metal is outside the range of the present invention. If the Al amount is too small, the amount of fume generation increases, and if it is too large, the ductility of the weld metal decreases.

Experiment No. 14 is an example in which the Ti / C ratio of the shell metal is No. 15 and Al / C ratio is out of the range of the present invention.
Fume generation is increasing.

Experiment No. 16 shows that C, Ti, and A of the outer skin metal were used.
In the example in which the l, Ti / C ratio, and Al / C ratio are all outside the range of the present invention, the fume generation amount has increased rapidly.

Experiments Nos. 17 and 18 are based on the flux Ti.
Or in the case where Ti oxide (converted to Ti) is outside the scope of the present invention,
If the amount is too small, the amount of fume generation increases and the stability of the arc deteriorates. If too large, the ductility of the weld metal decreases.

In Experiment No. 19, the Al content of the flux was out of the range of the present invention, and the ductility of the weld metal was reduced.

Experiment No. 20 is an example in which the Ti / C ratio of the flux is out of the range of the present invention, and no effect of reducing fume is recognized.

Experiment No. 21 is an example in which the C amount of the flux is out of the range of the present invention, and the amount of generated fume is increased.

Experiments Nos. 22 to 23 are examples in which the amount of alkali metal in the flux is out of the range of the present invention. If the amount is too small, arc stability is poor and spatter increases. If the amount is too large, spatter increases and the fume reduction effect is impaired.

Experiments Nos. 24 and 25 were performed using flux Fe
In examples where the amount is outside the scope of the present invention, too small an amount increases spatter of large grains. On the other hand, if the amount is too large, the thickness of the outer skin metal is reduced, so that the feeding property is deteriorated and defects such as undercut are liable to occur.

Experiment No. 26 is an example in which the metal powder ratio is out of the range of the present invention. The efficiency, which is a feature of the metal-based flux cored wire, is impaired, and the amount of slag increases, making continuous multilayer welding difficult. .

Experiment Nos. 27 to 28 are examples in which the amount of Mn is out of the range of the present invention. If the amount is too small, sufficient strength cannot be obtained.
The bead shape also deteriorates. If it is too large, the strength becomes excessive and low-temperature cracking easily occurs.

Experiment Nos. 29 to 30 are examples in which the Si content is out of the range of the present invention. If the Si content is too small, the bead shape deteriorates, and if it is too large, the toughness and ductility of the weld metal decrease.

Experiment No. 31 shows that the requirements (C, Ti, Al,
Ti / C, Al / C, Ti, C, Ti /
C) are all examples outside the scope of the present invention, in which the amount of generated fumes has increased sharply.

[0057]

[Table 1]

[0058]

[Table 2]

[0059]

[Table 3]

[0060]

[Table 4]

[0061]

As described in detail above, according to the present invention,
A gas-shielded arc welding metal-based flux-cored wire with less fume generation can be provided, and the high welding speed, welding workability, etc., which are features of the metal-based flux-cored wire, are not impaired.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the amount of fume generation and the amounts of Ti, Al, and C in the outer skin.

FIG. 2 is a diagram showing the relationship between the amount of fume generation and the amounts of Ti, Al, and C in the outer skin.

FIG. 3 is a diagram illustrating an example of a cross-sectional shape of a flux-cored wire.

FIG. 4 is a schematic explanatory view of an apparatus provided with a fume collection box.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tetsuya Hashimoto 100-1 Urakawachi, Miyama-ji, Fujisawa-shi, Kanagawa Prefecture Kobe Steel Fujisawa Works (56) References JP-A-7-276077 (JP, A) JP-A-3-294091 (JP, A) JP-A-2-3077698 (JP, A) JP-A-62-248597 (JP, A) JP-A-62-248593 (JP, A) JP-A-62-284893 (JP, A) JP-A-61-206589 (JP, A)

Claims (5)

(57) [Claims] 1. A gas-shielded arc-welded metal flux-cored wire obtained by filling a mild steel sheath with a flux, wherein C: ≦ 0.02% Ti: 0.01 as the mild steel sheath relative to the total weight of the sheath. 0.10% to 0.10% Al: 0.01 / 0.10% and Ti / C ≧ 1.0 Al / C ≧ 1.5 The total weight of wire as flux Ti or Ti oxide (converted to Ti amount): 0.03 to 1.0% At least one of alkali metal oxides and fluorides (converted to alkali metal element): 0.01 to 0.1. 15% Fe: 5-28% Metal powder: contains ≧ 94% (total weight% of flux), and further contains Mn (total Mn content in the hull): 0.5-3.6% Si (in the hull) Gas seal characterized in that it is a metal-based flux containing 0.1 to 1.8%. Arc welding metal-based flux cored wire. 2. The gas-shielded arc welding metal according to claim 1, wherein the flux further contains Al or Al ₂ O ₃ (converted to the amount of Al): ≦ 1.0% as a percentage of the total weight of the wire. Flux-cored wire. 3. The gas shielded arc according to claim 1, wherein the flux further contains C: ≦ 0.07% (where Ti / C ≧ 1.0) as a percentage of the total weight of the wire. Weld metal flux cored wire. 4. The mild steel outer skin contains C: ≦ 0.01% Ti: 0.01 to 0.10% Al: 0.01 to 0.05%, based on the total weight of the outer skin, and The gas-shielded arc welding metal flux cored wire according to claim 1, wherein the steel is a steel having a composition satisfying Ti / C ≧ 3.0 Al / C ≧ 2.0. 5. The gas-shielded arc welding metal flux cored wire according to claim 3, wherein the flux satisfies Ti / C ≧ 3.0.