JP2582601B2 - Composite wire for self-shielded arc welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a composite wire for self-shielded arc welding applied to outdoor all-position welding of ships, bridges, marine structures and the like.

[Conventional technology]

Unlike other welding materials, the self-shielding arc welding composite wire (hereinafter referred to as self-shielding wire) has a stronger self-shielding mechanism, and is less likely to generate welding defects due to wind. It has been adopted.

However, conventional self-shielded wires have a deoxidizing agent such as Al, Mg, etc., in order to prevent the generation of pores in the weld metal.
A large amount of the denitrifying agent was added, so that a large amount of Al remained in the weld metal, the crystal grains became coarse, and good low-temperature toughness was not obtained. In addition, CaF ₂ is a conventional self-shielded wire that has been used as a main metal fluoride.
F ₂ in order to significantly increase the fluidity of the slag, there is a problem with the bead formation properties in vertical position and upwardly orientation, application to construction site for all position welding is required is difficult.

In order to eliminate these disadvantages, for example, JP-A-54-15
No. 5139, JP-A-56-74395, JP-A-58-148095, JP-A-59-42198, good use characteristics in all positions welding by reducing the diameter of the wire And self-shielded wires with improved porosity and low-temperature toughness.

[Problems to be solved by the invention]

By using BaF ₂ as the metal fluoride and further reducing the diameter of the wire shown there, the low-temperature toughness and the weldability in all positions are certainly improved as compared with the conventional wire. Almost all metal fluorides except for CaF ₂ are chemically synthesized, and their particle size is small, the apparent density is small, and the particle size of iron oxide is small. The variation in the rate is large, and there is a problem in wire production such as disconnection at the time of drawing, and it is not always satisfactory in terms of stability of impact value and quality performance.

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned drawbacks of conventional wires and to expand the field of application, and to provide a self-shielded wire that stabilizes low-temperature toughness, improves wire productivity, and provides stable quality performance. It is something to offer.

[Means for solving the problem]

The feature of the wire according to the present invention is that a component of the steel sheath is C: 0.06% or less, P: 0.009% or less, and N: 0.004% or less. One or two of CaF ₂ and BaF ₂ having an apparent density of 1.3 g / cm ³ or more:
One or more iron oxides having a particle size range of 3% to 12% and a particle size range of 74μ to 350μ of 50% or more: 0.2 to 5%, Al:
0.5 to 3%, Mg: 0.5 to 3%, Mn: 0.1 to 2%, Sum of the amount of Fe and iron powder added as an alloy with Al, Mg, Mn: 0.5 to 10%, or Al, Mg, Fe powder amount of Fe added as alloy with Mn
Total with Ni: 0.5-10%, and CaF ₂ , BaF ₂
0.1 to 2%, and the apparent density of the total mixed flux is 1.4 g / cm ³
The above powdery and granular fluxes are
By filling up to 30%, the low-temperature toughness is excellent, and the productivity of the wire can be improved and the quality performance can be stabilized.

[Operation] The reason why the wire according to the present invention is configured as described above together with the operation will be described in detail below.

First, in the present invention, the composition of the steel shell is C: 0.06% by weight.
In the following, it is necessary to use steel materials with P: 0.009% or less and N: 0.004% or less. That is, in order to obtain a toughened weld metal, the C in the weld metal must be reduced to 0.07% or less. However, considering the flux and the lubricant on the wire surface, the C in the steel shell is reduced to 0.06% or less. Should. Although P and N are inevitable impurities, P impedes the high temperature crack resistance of the weld metal and N significantly deteriorates the toughness.
% And N is preferably 0.004% or less.

 Next, the composition of the flux component will be described.

The role of metal fluoride, which is used in large quantities in self-shielded wires, is to encapsulate the weld metal as a slag agent to improve the bead shape, and to shield the arc and molten pool from the atmosphere as a gas generating substance, and to remove degassing elements. And the impurities in the molten metal are raised to clean the weld metal. This improves toughness.

Metal fluorides are almost chemically synthesized, except for CaF ₂ , and have a fine particle size. CaF ₂ naturally produced
Represents a large amount of SiO ₂ as disclosed in JP-A-56-19997.
Therefore, CaF ₂ is subjected to a treatment for improving the quality thereof, and its particle size is inevitably fine. Accordingly, the metal fluoride used as a main component of the self-shielded wire in a large amount has a small particle size and a small apparent density, which causes a reduction in production yield and a change in the flux filling rate in wire production.

The present inventors have conducted various studies to solve these problems, and as a result, as shown in FIG.
It has been found that by setting the apparent density of F ₂ and BaF ₂ to 1.3 g / cm ³ or more, the productivity of the wire can be greatly improved and the quality can be stabilized. As a result, CaF ₂ , BaF ₂
Must be regulated to 1.3 g / cm ³ or more. In the present invention, one or two of CaF ₂ and BaF ₂ are contained in an amount of 3 to 12% based on the total weight of the wire, because the wire diameter is 2.
When high efficiency welding is required in the downward and horizontal fillet welding positions with a large diameter of 0 mm or more, CaF ₂ is the main component, while a small diameter wire of 2.0 mm or less has excellent weldability in all positions. This is because BaF ₂ as a main component has excellent properties in slag encapsulation and bead formation.

If CaF ₂ and BaF ₂ are less than 3%, these characteristics are not sufficiently exhibited, while if more than 12%, the arc becomes unstable,
The amount of slag generated is excessive, and defects such as slag entrapment are likely to occur. Therefore, the apparent density of 1.3 g / cm ³ or more of CaF ₂ and BaF
One or _two will be in the range 3 to 12%.

Incidentally, in claim (3) of the present invention, a metal fluoride other than CaF ₂ and BaF ₂ is added in a range of 0.1 to 2%.
The reason is that, in addition to effective shielding by adding a small amount such as LiF, the purpose is to improve arc stability such as alkali metal fluoride, and if the added amount is less than 0.1%, the effect is not sufficiently exhibited. If it exceeds 2%, the arc becomes unstable, and the amount of spatter generated is undesirably increased. Therefore, it is set in the range of 0.1 to 2%. As metal fluorides other than CaF ₂ and BaF ₂ , MgF ₂ , MnF ₂ , SrF, LiF, NaF, K ₂ Si
F ₆ , Na ₂ SiF _{6 and the} like are effective.

In the present invention, iron oxide is used as an essential component. First, the reason is that the weld metal excessively deoxidized by Al and Mg
This is because oxygen is supplied to promote nucleation of ferrite, thereby improving the toughness of the weld metal.

Second, since iron oxide has a low melting point, high melting point Al ₂ O ₃ and MgO generated by the deoxidation reaction of Al and Mg are floated as slag to prevent welding defects such as slag entrainment. This is because Third, by adding iron oxide, an appropriate slag fluidity can be obtained for welding in all positions, so that the bead appearance and shape are improved and the slag shield is enhanced. . If the content of iron oxide is less than 0.2%, the above effect is not obtained. On the other hand, if it exceeds 5%, the droplet transferability is deteriorated and defects such as slag entrapment due to excessive slag are liable to occur.
Therefore, the appropriate range of iron oxide is set to 0.2 to 5%.

As the iron oxide, iron oxide represented by FexOy, for example _{FeO, Fe 2 O 3, Fe} 3 O 4 may be added in the form of such, or oxidation of the expressed Li or alkaline earth metals with MxFeyOz Oxides (for example, LiFeO ₂ , Sr ₂ Fe
O ₄ , Sr ₂ Fe ₂ O ₃ , Sr ₇ Fe ₁₀ O ₂₂ , BaFe ₂ O ₄ , BaFe ₁₂ O _19, etc.).

The reason why the particle size of these iron oxides is in the range of 74μ to 350μ is regulated to 50% or more is that the iron oxide particle size is 74μ or less excluding hematite, especially alkaline earth. Oxides of similar metals are used as magnetic materials for magnetic tapes, and the particles themselves are ultrafine powders having a particle size of 1 μm or less. Therefore, when these are used, they are not dispersed at the time of mixing and condense to cause segregation, so that the intended performance cannot be obtained. The present inventors have studied the particle size of iron oxide in these mixed fluxes, and as a result,
If it is 50% or more, it is confirmed that the dispersibility of the compounded and mixed flux is good and no segregation occurs, so the particle size of the iron oxide is in the range of 74μ to 350μ. Was 50% or more. However, even if the particle size is too coarse, the wire may be broken during the production of the wire.

Al acts as a strong deoxidizing and denitrifying agent to improve the porosity of the weld metal, and is an essential element for self-shielded wires. If it is less than 0.2%, the above effect is insufficient, and welding defects such as pits and blowholes are generated. On the other hand, if it exceeds 3%, the amount of Al in the weld metal becomes excessive, leading to coarsening of crystal grains and toughness. Is not preferred because it deteriorates. Therefore, Al is set to 0.2 to 3%. Incidentally, Al may be used alone, or Fe-Al, Al-Mg, Zr-Al, Li-Al, Ca-Al, Ca-Al-
It may be added in the form of an alloy such as Mg.

Mg is not only a powerful deoxidizer but also an element that improves the transferability of droplets. Addition of Mg makes the droplet particles finer,
Spray droplet transfer. If the Mg content is less than 0.5%, the above effect is insufficient. If the Mg content is more than 3%, spattering frequently occurs and fume increases, which is not preferable. Therefore, the appropriate range of Mg is set to 0.5 to 3%. Note that Mg may be used alone or may be added in the form of an Mg alloy such as Al-Mg, Ni-Mg, Li-Mg, Ca-Mg, and Fe-Mg.

The reason for adding Mn in an amount of 0.1 to 2% is to provide necessary and sufficient strength suitable for a welded joint. If it is less than 0.1%, the required strength and good bead shape cannot be obtained,
On the other hand, if it exceeds 2%, the strength becomes too high and the crack resistance is deteriorated. Therefore, the addition amount of Mn is set to 0.1 to 2%. In addition, Mn can be used alone, in the form of various alloys including iron alloys such as Fe-Mn, oxides such as MnO, and composite oxides such as LiMnO ₂ .

The reason that the sum of the amount of Fe added as an alloy with Al, Mg, and Mn and the amount of iron powder is set to 0.5 to 10% is that iron powder is used for the purpose of increasing the welding speed, and furthermore, low-temperature toughness of marine structures and the like ( 20
° C to -40 ° C).
Ni can be added to further improve the low-temperature toughness.
Therefore, the content of these should be in the range of 0.5 to 10%.

The above are the essential components of the particulate flux in the wire of the present invention, but in the present invention, in order to further enhance the shielding effect, metal such as Li ₂ CO ₃ , BaCO ₃ , CaCO ₃ , SrCO ₃ , MgCO ₃ , MnCO ₃ Adding carbonate within a range that does not cause deterioration in workability such as spattering, and as a physical property modifier for slag, CaO, Al ₂ O ₃ , MgO, SiO ₂ , TiO ₂ , ZrO ₂ , Na ₂ O, An oxide such as K ₂ O may be added as needed.

In the self-shielded wire of the present invention, the powdery or granular flux having an apparent density of the mixed total flux of 1.4 g / cm ³ or more was in the range of 10 to 30% based on the total weight of the wire. The reason why the apparent density of all the mixed fluxes was 1.4 g / cm ³ or more was that the apparent density of CaF ₂ and BaF ₂ and the particle size of iron oxide regulated by the present invention, and the apparent flux as a whole This is because it has been confirmed that by regulating the density, the productivity can be significantly improved. Therefore, the apparent density of all the mixed fluxes was set to 1.4 g / cm ³ . If the flux filling rate is less than 10%, the above effects of the flux cannot be expected, and pores are generated in the weld metal, the slag encapsulation property is impaired, and if it exceeds 30%, the amount of slag generated This is because, as a result, the required mechanical properties are hardly obtained, and furthermore, the wire drawing workability is reduced and the wire production becomes difficult.

As the steel sheath, a low carbon steel within the composition regulation range is used, but a low alloy steel or a steel alloy steel satisfying the composition regulation range can be used. There is no restriction on the cross-sectional shape of the wire, and a relatively simple cylindrical shape is used for a small diameter of 2 mmφ or less, and a sheath material is used for a large diameter wire of about 2.4 to 3.2 mmφ. It is common to have a complicatedly folded structure. In the case of a seamless wire, it is also effective to subject the surface to Cu plating.

〔Example〕

Table 1 shows the composition of the steel shell used for the trial production, Table 2 shows the composition of the wire flux, and Table 3 shows the test results. In Tables 2 and 3, Nos. 1 to 6 are comparative examples, and Nos. 7 to 15 are examples of wires according to the present invention.

All were finished to 2.0mmφ wire using the steel outer skin shown in Table 1 and welded by welding 8 layers 15 passes with JIS G3106 SM-50B 20mmt × 350mml at 250A DC (-), ExT: 20mm The mechanical properties of metal components were investigated. The groove shape and the procedure for collecting the test piece were prepared in accordance with JISZ3111.

As is evident from the test results in Table 3, the wires of Comparative Examples Nos. 1 to 6 in which the composition of the outer skin and the flux are outside the present invention have a significantly reduced impact value at −40 ° C. No improvement in toughness was observed. In No. 6, the flux composition was within the present invention, but P in the weld metal was as high as 0.012% due to the high P of the shell component, and no improvement in toughness was observed.

On the other hand, the wires of the present invention of Nos. 7 to 15 all have an impact value of 10 kgf-m or more even at -40 ° C.
It was confirmed that the low-temperature toughness was also good.

[Effects of the Invention] The present invention is configured as described above. Particularly, by controlling the apparent density of the metal fluoride as the main component and the particle size of the iron oxide, the productivity of the wire is greatly improved. Along with
It has become possible to reduce the fluctuation of the flux filling rate. Further, by combining the outer shell component and the flux structure, it is possible to provide a composite wire for self-shielded arc welding that can obtain good low-temperature toughness, and can achieve higher grade and higher toughness of the molten material.

[Brief description of the drawings]

FIG. 1 is a drawing showing the relationship between the apparent densities of CaF ₂ and BaF ₂ and the fluctuations in wire production yield and flux filling rate.

Claims (3)

(57) [Claims] 1. A cavity surrounded by a steel sheath whose components of the steel sheath are C: 0.06% or less (% by weight: the same applies hereinafter), P: 0.009% or less, and N: 0.004% or less, relative to the total weight of the wire. The apparent density is 1.
One or two of CaF ₂ and BaF ₂ of ³ g / cm ³ or more: 3 to 12
% Or more, at least one of iron oxides having a particle size range of 74 μ to 350 μ is 50% or more: 0.2 to 5%, Al: 0.5 to 3%
%, Mg: 0.5 to 3%, Mn: 0.1 to 2%, the sum of the amount of Fe and the amount of iron powder added as an alloy with Al, Mg, and Mn: 0.5 to 10% The apparent density of flux is 1.4g / c
It is m ³ or more particulate flux relative to the total wire weight
Composite wire for self-shielded arc welding characterized by being filled by 10 to 30%. 2. The total of the amount of Fe, the amount of iron powder, and the amount of Ni added as an alloy of Al, Mg, and Mn instead of the amount of Fe and the amount of iron powder: 0.5 to 10%
The composite wire for self-shielded arc welding according to claim 1. 3. The composite wire for self-shielded arc welding according to claim 1, wherein one or more metal fluorides other than CaF ₂ and BaF ₂ are contained in an amount of 0.1 to 2%. .