JPH07276087A - Gas shield arc welding metal-flux cored wire - Google Patents

Abstract

PURPOSE:To produce a gas shield arc welding metal flux cored wire small in fumes to be generated. CONSTITUTION:In a gas shield arc welding metal flux cored wire obtd. by filling the sheath made of soft steel with flux, the sheath made of soft steel is constituted of a steel having a compsn. contg., in the ratio to the total weight of the outer surface, <=0.02% C, 0.01 to 0.20% Ti and 0.01 to 0.10% Al and satisfying Ti/C >=1.0 and Al/C >=1.5. As flux, metal type flux contg., in the ratio to the total weight of the wire, one or more kinds among the oxides and fluorides of alkali metals excluding Cs and Rb by 0.01 to 0.30% (the value expressed in terms of alkali metal elements), 5 to 28% iron powder, metal powder by >=94% (to the total weight % of the flux) and one or two kinds of Cs and Rb by 0.001 to 0.10% (the value expressed in terms of Cs and Rb) and furthermore contg. Mn by 0.5 to 3.6% (totalling also the amt. of Mn in a hoop) and Si by 0.1 to 1.8% (totalling also the amt. of Si in a hoop) is used.

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 gas shielded arc welding metal-based flux-cored wire with reduced fume generation.

[0002]

2. Description of the Related Art In recent years,
Demand for gas-shielded arc welding flux-cored wire is rapidly expanding in terms of ease of welding and efficiency. Especially, the metal flux cored wire is
Compared with conventional welding wires, it has the features of being able to perform high-efficiency welding and producing a small amount of slag, which makes it difficult to penetrate into fields such as steel frames, bridges, and industrial machinery. There is something to watch.

However, the biggest drawback of this type of wire is that it is used at a relatively high current value in order to obtain high efficiency, so that a large amount of fumes are generated, which deteriorates the welding work environment, and the removal of 3K or the like. It cannot be said that it is not preferable from the viewpoint of.

In view of these circumstances, it is an object of the present invention to provide a gas shielded arc welding metal flux-cored wire which produces a small amount of fumes.

[0005]

A technique for reducing welding fumes is disclosed in Japanese Patent No. 1403569 by the present applicant.
No. 1572313, No. 1572327, etc., 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 deposition rate, and the amount of welding fumes increases exponentially as the current increases. I can not cope.

[0006] Therefore, as a result of intensive studies on the measures for reducing the fume generation amount in the metal flux-cored wire, the present inventors have found that the addition of Cs and Rb to the flux is effective, and have already proposed it. (Patent application flat 4
-285033).

On the other hand, it was clarified and proposed that the adjustment of C, Ti, and Al in the outer skin and the adjustment of Ti, oxides of alkali metals and fluorides in the flux are also effective as a fume reduction measure (Japanese Patent Application No. Hei 10 (1999) -108242). 5-42168).

The inventors of the present invention have aimed to further reduce the fume, use an outer shell in which the amounts of C, Ti and Al are appropriately controlled, and use C as an alkali metal in the filling flux.
It was clarified that the addition of s and Rb has a remarkable synergistic effect in reducing the amount of fumes, and the present invention has been completed here.

That is, the present invention relates to a gas shielded arc welding metal flux cored wire obtained by filling a flux into a mild steel outer sheath, wherein the ratio of the mild steel outer sheath to the total weight of the outer sheath is C: ≤ 0.02% Ti : 0.01 to 0.20% Al: 0.01 to 0.10%, and Ti / C ≧ 1.0 Al / C ≧ 1.5, a steel having a composition satisfying Ti / C ≧ 1.0 Al / C ≧ 1.5. , One or more kinds of alkali metal oxides and fluorides excluding Cs and Rb in terms of the total weight of the wire (calculated as alkali metal element): 0.01 to 0.30% Iron powder: 5 to 28% Metal powder : ≧ 94% (% by total flux) Cs and / or Rb compounds, one or more in total
(Cs, Rb conversion value): 0.001 to 0.10% is contained, and Mn (total Mn amount in the hoop): 0.5 to 3.6% Si (Si amount in the hoop is also included. Summarized): Gas shielded arc welding metal flux cored wire characterized by being a metal flux containing 0.1-1.8%.

[0010]

The present invention will be described in more detail below.

First, the reason why the components of the wire sheath are limited in the present invention will be described. Various experiments were conducted in order to examine means for reducing welding fume from the outer skin component side, and an example of experimental results showing the essence of the results obtained by the experiments will be described below.

In these experiments, No. 1 in Table 2 described later was used.
The flux of the composition of (flux rate 15%)
i, Mild steel shell with Al content (C: 0.003 to 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%), 1.4 mm
A flux-cored wire having a diameter was produced.

Next, under the following fixed welding conditions, downward bead-on-plate welding was performed using a test plate JIS G3106 SM490A (plate thickness 12 mm), and the amount of welding fumes generated during that time was 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 liters / min

1 and 2 show the amount of welding fumes and Ti, Al and C in the outer skin based on the data obtained by the experiment.
This is the relationship with quantity. As shown in FIGS. 1 and 2, in order to reduce the amount of welding fume generated, in addition to the C content reduction of the conventional technique for the outer skin component, Ti, Al
It was confirmed that the combined addition of 0.01% or more of each is an effective means. Of these, it has been found that Al has little effect by itself, and a remarkable effect is produced only by combined addition with Ti. It was also found that the addition effect of Cs and Rb in the flux makes the effect of reducing welding fume more remarkable. The welding fume reduction effect of Ti and Al is C ≦ 0.02%, Ti / C ≧ 1.0, Al /
It was also found that it was obtained when C ≧ 1.5.

The reason why the effect of reducing welding fumes is obtained by Ti and Al is that Ti and Al have a strong affinity for oxygen and form a high-freezing point oxide, so that the suspended droplet at the tip of the wire during the arc welding process. It is considered to form an oxide film on the surface and suppress the explosive formation of CO and CO ₂ which are fumes generating sources as a result of the reaction between C and oxygen.

Further, the upper limits of the amounts of Ti and Al must be set to 0.20% and 0.10%, respectively, in order to avoid deterioration of material properties such as deterioration of ductility and hardening which occur as a result of retention in the weld metal. Investigated.

For the above reasons, a mild steel shell suitable for reducing welding fume is C: ≤ 0.02% Ti: 0.01 to 0.20% Al: 0.01 to 0 in terms of the total weight of the shell. Steel containing 0.10% and having a composition satisfying Ti / C ≧ 1.0 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. Considering the workability in the rolling and / or drawing process in wire production, Mn: 0.0
The range of 10 to 0.70% and Si ≦ 0.35% is desirable.

Next, the reason why the flux component to be filled is limited will be described. The flux component is weight% with respect to the entire wire.

One or two compounds of Cs and / or Rb
The above total (converted into Cs and Rb ): 0.001 to 0.10% The total of one or more Cs and Rb compounds is 0.0.
If it is less than 01%, there is no fume reduction effect (see FIG. 3).
However, if it exceeds 0.10%, the moisture absorption resistance deteriorates, the porosity resistance decreases, the amount of diffusible hydrogen in the deposited metal increases, and the crack resistance deteriorates. Although Cs and Rb are added in an appropriate form, especially Cs is Cs ₂ CO ₃ or TiO ₂ , Si
It can be added in the form of a composite oxide with O ₂ . The above-mentioned addition amount of Cs and / or Rb in the present invention is an amount obtained by converting Cs and / or Rb in those compounds into an element. More preferably, it is 0.001 to 0.010%.

Alkali metal oxides other than Cs and Rb,
One or more fluorides (converted to alkali metal elements): 0.01
~ 0.30% arc stability and spatter reduction, Li, N
Add alkali metal components such as a and K. Since the alkali metal has a remarkable hygroscopic property, it is preferable to use one or more kinds in the form of oxide or fluoride. The range limited to 0.
If it is less than 01%, the effect of improving arc stability and reduction of spatter cannot be obtained, and if it exceeds 0.30%,
This is because these alkali metals have a high vapor pressure, and conversely the spatter increases, and the effect of reducing welding fume by Ti and Al cannot be obtained.

In addition, feldspar, anhydrous sodium silicate, water glass,
Since complex oxides such as Li, Na and K, fluorides such as cryolite, potassium silicofluoride and sodium silicofluoride, and a small amount of alkali metal carbonates are decomposed by arc heat to become oxides, The same effect can be obtained. The addition amount in the present invention is a value converted into an alkali metal element. More preferably 0.01 to 0.1
It is 0%.

Iron powder: 5 to 28% Iron powder is added according to the flux rate in order to obtain a high deposition rate. That is, when the flux ratio (total weight% of the flux to the wire) is less than 10%, the thickness of the outer metal is too thick, so that large-grain spatter increases, while when it exceeds 30%, the outer metal thickness decreases. Since the wire becomes softer, the feedability is reduced, and the spread of the arc becomes significant, and the penetration depth and undercut are likely to occur. Therefore, the flux rate is preferably in the range of 10 to 30%.

Iron powder is added according to the above-mentioned flux rate, but if it is less than 5%, the remarkable high deposition rate, which is a feature of the metal flux-cored wire, cannot be obtained, and if it exceeds 28%, a deoxidizing agent, etc. Since other components are insufficient, it becomes 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 iron powder is set in the range of 5 to 28%. It is more preferably 8 to 15%.

Metal powder: ≧ 94% (vs total flux%) In order to secure the high welding speed characteristics and the amount of slag capable of continuous multi-layer welding, which are the features of the metal-based flux-cored wire, oxides, fluorides, carbonates The ratio of metal powder in the flux, excluding non-metallic substances such as salt, must be 94% or more.

[0027]Mn (total Mn amount in the outer skin): 0.5
3.6%  Mn is a deoxidizer, which improves toughness by improving strength and hardenability and
Improvement of bead shape by increasing viscosity of molten metal slag (especially
For horizontal fillet), also consider the amount of Mn in the outer skin
Added. In that case, if the Mn content is less than 0.5%, for mild steel
As a result, sufficient strength cannot be obtained and the bead shape is also good.
However, if it exceeds 3.6%, the weld metal strength will be excessive.
Therefore, low temperature cracking is likely to occur, so the above range is set. Na
The Mn source is Mn, Fe-Mn, Fe-Si-Mn.
Which can be mentioned. More preferably 0.5-2.5%
It

Si (total amount of Si in the outer skin): 0.1-
1.8% Si has the same effect as Mn. However, if the Si content is less than 0.1%, the deoxidizing agent, the toughness improving effect and the bead shape improving effect cannot be obtained, and if the Si content exceeds 1.8%, the Si content in the weld metal becomes excessive and conversely the toughness is deteriorated. Since the ductility and the ductility decrease, the above range is set. The source of Si is Si or Fe.
Alloys such as -Si, Fe-Si-Mn, and Fe-Si-Mg are mentioned. More preferably, it is 0.3 to 1.2%.

In addition, in order to further improve the bead appearance and shape within the range where the above-mentioned metal powder ratio is satisfied, SiO ₂ ,
Oxides such as ZrO ₂ , CaO, and FeO are added, and in order to improve the slag releasability, high temperature cracking does not occur in the range of 0.1.
% (Total weight% of the wire) or less bismuth oxide (Bi ₂ O ₃ ) or 0.2% (total weight% of the wire) or less MgO or Mg within the range where the bead shape does not deteriorate. You can also

Further, the base steels to which the present invention is applied are mainly mild steel and high-strength steel. Depending on the application, metals or alloys such as Ni, Cr, Mo and Cu may be added to produce low-alloy steel, high-alloy steel, etc. There is no problem even if it is expanded and applied.

The type of shield gas is mainly carbon dioxide gas, but Ar, He or the like may be used, or a mixed gas thereof may be applied. Also, the cross-sectional shape of the flux-cored wire is not limited at all, and for example, as shown in FIG.
Various shapes exemplified in (B), (C), (D) and the like can be used. In the case of the shape (D), the wire surface may be plated with Al, Cu or the like, and the plating amount is 0.05 to 0.3.
0% is suitable. Wire diameter is 1.2mm depending on the application
φ, 1.4 mmφ, 1.6 mmφ, 2.0 mmφ, 2.4 mmφ,
It can be arbitrarily selected from 3.2 mmφ.

Next, examples of the present invention will be described.

[0033]

EXAMPLE Using a shell metal made of steel having the composition shown in Table 1, a filling flux having the composition shown in Table 2 was prepared.
With the cross-sectional shape of (B) in Figure 4, the test wire (wire diameter 1.4
mmφ) was produced. Next, using each flux-cored wire, welding was performed under the following conditions, and the amount of fume generated, workability, etc. 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 liters / min Distance between chip base materials: 25 mm Test plate: JIS G 3106, SM490A (12 mmt) Welding method: Downward bead on plate welding

(Fume measurement method) The amount of fume generated is determined by JI
According to S Z 3930 “Measurement method of total fume amount of coated arc welding rod”, by measuring the weight of fume generated when welding for 1 minute, the value per unit time (g
/ Min) (the number of repetitions = 3 average value) was determined. Fume was collected by an apparatus equipped with a collection box shown in FIG.

(Workability) Workability was evaluated by sensory evaluation.

The results of these experiments are shown in Table 3 and can be considered as follows.

Experiment No. 2, No. 3, No. 6, No. 7, N
No. 15 and No. 18 are examples of the present invention, and the fume generation amount is extremely small in both cases. On the other hand, since the comparative example does not completely satisfy the requirements of the present invention, as shown below, other performances such as welding workability are inferior even when the fume generation amount is large or small.

In Experiment No. 1 and No. 4, Cs and Rb were out of the range of the present invention. When the amount was too small, the amount of fumes increased, and when the amount was too large, the moisture absorption resistance of the wire deteriorated, and the resistance to resistance increased. Porosity, crack resistance, etc. are reduced.

Experiments No. 5 and No. 8 have an alkali metal content outside 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, the spatter rather increases, and the effect of reducing the amount of fumes is impaired.

Experiments No. 9 and No. 10 are those in which the amount of iron powder is out of the range of the present invention. When the amount is too small, the welding efficiency is lowered and the spatter is increased, and when the amount is too large, the mechanical properties of the weld metal are deteriorated. It is difficult to secure and prevent welding defects such as pits and blowholes.

Experiments No. 11 and No. 12 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 and the bead shape is also deteriorated. If it is too large, the strength becomes excessive, and cold cracking is likely to occur.

Experiments No. 13 and No. 14 are examples in which the amount of Si is outside the range of the present invention. If it is too small, the bead shape deteriorates, and if it is too large, the toughness and ductility of the weld metal deteriorate.

Experiment No. 16 is an example in which the amount of C in the outer metal is outside the range of the present invention, and the amount of fumes generated is increased. Experiments No. 17 and No. 21 are examples in which the amount of Al in the coating metal is out of the range of the present invention. When the amount is too small, the fume generation amount increases, and when the amount is too large, the ductility of the weld metal decreases. Experiment No. 1
Nos. 9 and 20 are examples in which the Ti content of the outer metal is out of the range of the present invention, and when the Ti content is too small, the fume generation amount increases, and when the Ti content is too large, the yield to the weld metal increases and the ductility decreases.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

[Table 3]

[0048]

As described in detail above, according to the present invention,
It is possible to provide a gas shielded arc welding metal flux cored wire that can significantly reduce the amount of fume generated, and does not impair the high welding speed, welding workability, etc., which are features of the metal flux cored wire, and its effect is extremely high. It is remarkable.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a fume generation amount and a C amount in a crust.

FIG. 2 is a diagram showing the relationship between the fume generation amount and the Ti amount in the outer skin.

FIG. 3 is a diagram showing the relationship between the amount of fume generated and the amounts of Cs and Rb in the flux.

4 (A), (B), (C), and (D) are diagrams showing examples of cross-sectional shapes of a flux-cored wire.

FIG. 5 is a schematic explanatory diagram of an apparatus including a fume collection box.

Claims (1)

[Claims] 1. A gas shielded arc welding metal flux cored wire comprising a mild steel outer shell filled with flux, wherein the ratio of the mild steel outer shell to the total weight of the outer shell is C: ≤0.02% Ti: 0.01. ~ 0.20% Al: 0.01-0.10% and a composition of Ti / C≥1.0 Al / C≥1.5, the total weight of the wire as flux. In proportion to one or more of alkali metal oxides and fluorides excluding Cs and Rb (calculated as alkali metal element): 0.01 to 0.30% Iron powder: 5 to 28% Metal powder: ≥94% (Total weight% of flux) Total of one or more compounds of Cs and / or Rb
(Cs, Rb conversion value): 0.001 to 0.10% is contained, and Mn (total Mn amount in the hoop): 0.5 to 3.6% Si (Si amount in the hoop is also included. (Total): Gas-shielded arc welding metal-based flux-cored wire, which is a metal-based flux containing 0.1 to 1.8%.