JPH0732151A - Auxiliary composite wire for gas shielded arc welding of galvanized steel sheet - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an auxiliary composite wire for preventing blowholes in gas shielded arc welding of galvanized steel sheet. [Composition] When gas-shielded arc welding a galvanized steel sheet, when supplying a blowhole improving element into the arc and / or the molten pool by an auxiliary composite wire having a composition different from that of the welding wire, Cr as a blowhole improving element group, V, B, Ti, Ta, W, P, Fe containing one or more kinds, and the total content of the elements is 10% or more based on the weight of the wire excluding the flux,
Furthermore, an auxiliary composite wire whose outer part is an outer sheath made of unavoidable impurities and flux inside it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas shielded arc welding method and auxiliary wire for galvanized steel sheet which can greatly improve blowholes generated in beads during gas shielded arc welding.

[0002]

2. Description of the Related Art The bond strength of a bead formed by arc welding is greatly reduced by a blowhole formed in the bead. When welding non-plated materials such as cold-rolled steel sheets and hot-rolled steel sheets, blowholes of this kind are rarely formed if proper welding conditions are selected. However, when welding galvanized steel sheets, it is difficult to suppress the occurrence of blowholes. The cause of blowholes found in welded joints of galvanized steel sheets is that the zinc component in the plating layer existing near the joint interface is gasified and blown into the molten steel consisting of the steel sheet and welding wire components, and zinc gas This is because the bead is formed while remaining.

As a method of solving this problem, a Fe-P-Zn compound having a melting point higher than that of zinc is formed by previously supplying a certain amount of a composition containing phosphorus iron as an active ingredient onto a welding line which is a joining interface. A method for detoxifying zinc (Japanese Patent Laid-Open No. 63-108995) is disclosed. In addition, TiO ₂ , ferro titanium, ferro manganese,
By applying at least one kind of powder group such as ferrosilicon, iron, and illuminite to the welding line before welding,
A method (Japanese Patent Laid-Open No. 61-30286) for improving the stirring effect in the molten pool and promoting the floating of blowholes is disclosed.

[0004]

However, even if the above-mentioned method is used, it is not possible to sufficiently suppress blowholes generated in the arc-welded joint, and sufficient joint strength cannot be obtained. Therefore, an industrially effective gas shielded arc welding method for galvanized steel sheets is required.

[0005]

The present invention has been made to advantageously solve the above problems, and its features are shown in the following items.

(1) In the case of gas shielded arc welding of galvanized steel sheet, when supplying blowhole improving elements into the arc and / or the molten pool by an auxiliary composite wire having a composition different from that of the welding wire, a group of blowhole improving elements Cr, V, B, Ti, Ta, W, P, F
characterized in that it contains one or more of e, the total content of the above elements is 10% or more based on the weight of the wire excluding the flux, and that the balance is coated with an outer coat of inevitable impurities. Auxiliary composite wire for gas shield arc welding of galvanized steel sheet.

(2) In the case of gas shielded arc welding of galvanized steel sheet, when the blowhole improving elements are supplied into the arc and / or the molten pool by the auxiliary composite wire having a composition different from that of the welding wire, a group of blowhole improving elements Cr, V, B, Ti, Ta, W, P, F
and one or more of e, and the total content of the elements is 10% to 9 based on the weight of the wire excluding the flux.
Auxiliary composite wire for gas shielded arc welding of galvanized steel sheet, which is obtained by coating a mixture of particles and flux having a content of 0% and the balance being unavoidable impurities with a metal sheet.

(3) In the case of gas shielded arc welding of galvanized steel sheet, when supplying blowhole improving elements into the arc and / or the molten pool by an auxiliary composite wire having a composition different from that of the welding wire, a group of blowhole improving elements Cr, V, B, Ti, Ta, W, P, F
and one or more of e, and the total content of the elements is 10% to 9 based on the weight of the wire excluding the flux.
Auxiliary composite wire for gas shielded arc welding of galvanized steel sheet, characterized in that the content of 0% and the remainder being inevitable impurities are covered with a metal plate.

[0009]

The present invention is based on the finding that blowholes in the weld bead remain as bubbles after the galvanized layer near the bead is gasified and penetrates into the molten pool and solidifies. In order to prevent the intrusion of zinc gas, which is the cause, at the initial stage of melting of the molten pool, form a zinc gas barrier layer enriched with blowhole improving elements at the molten pool interface near the root of lap fillet welding. Was found to be effective and was made. Further, in order to form the zinc gas barrier layer by concentrating the blowhole improving element on the interface, an auxiliary wire having a composition different from that of the welding wire and containing the blowhole improving element may be supplied into the arc and / or the molten pool. I found that.

The present inventors believe that the blowhole-improving element group is concentrated at the interface of the molten pool to improve the viscosity of molten steel or increase the interfacial tension to prevent the penetration of zinc gas. Further, it has been found that Cr, V, B, Ti, Ta, W, P and Fe are effective as the blowhole improving element group. As an aspect of adding this blowhole improving element to the auxiliary composite wire, considering the blowhole improving effect, the usability of the wire, etc., the above (1),
There are auxiliary composite wires of (2) and (3). (2),
In (3), if the particles comprising the blowhole improving element are coated with a metal plate, it is not necessary to mainly use the outer metal plate as the blowhole improving element, and the workability and formability of the wire can be increased by increasing the addition of the blowhole improving element. It is possible to prevent the deterioration of the workability, so that workability is improved. Furthermore, since the wire contains particles consisting of flux and / or blowhole improving elements, liquid convection in the center of the molten pool is promoted, and gas components other than zinc in the molten pool are also promoted to float and be removed. .

Next, the reasons for limiting the content of the blowhole improving element will be described. The auxiliary composite wire of (1) has Cr, V, B, Ti, T as the blowhole improving element group on the outer skin.
Contains one or more of a, W, P and Fe, and the total content is 10% per weight of wire excluding flux.
The above must be contained in the outer skin. If it is less than 10%, the effect of preventing the intrusion of zinc gas is not sufficient, and it is also difficult to sufficiently secure the rigidity of the outer skin. The outer skin may contain unavoidable impurities in the balance of the blowhole improving element to the extent that the effect of improving the blowhole is not impaired. The inevitable impurities referred to here are C and S.
i, Mn, S, Mo, Nb, O, N, Al and the like. The flux may be the flux of a flux-cored wire used in ordinary gas shielded arc welding, and the particle size of the flux may be powder and may be set appropriately.

In the auxiliary composite wire of (2), the particles mixed with the flux include Cr, V, and
One or more of B, Ti, Ta, W, P and Fe must be contained in an amount of 10% to 90% based on the weight of the wire excluding the flux. If it is less than 10%, the above zinc gas invasion preventing effect is not sufficient. Further, if it exceeds 90%, the rigidity of the metal layer coating the outside is not sufficient, which is not preferable as an industrial product. The composition of the particles mixed with the flux may be the same composition, but may be a plurality of compositions. The metal layer for coating the outer side contains Fe, further contains C, Si, Mn, P, S, and Nb, Ti, Ni, Cr, Mo, V, B, Al, N.
Of these, one containing one or two or more of them, and one mainly containing Cu may be used. The balance of this metal layer may be unavoidable impurities.

As the auxiliary composite wire (3), Cr, V, and
It is necessary to contain one or more of B, Ti, Ta, W, P and Fe in an amount of 10% to 90% based on the weight of the wire. If it is less than 10%, the effect of preventing the intrusion of zinc gas is not sufficient. Further, if it exceeds 90%, the rigidity of the metal layer covering the outside is not sufficient and the metal layer may be damaged by the shield gas or the like and the particles inside may be scattered. The composition of the particles inside the wire may be the same, but a plurality of types may be used. The aspect of the metal layer coating the outside may be the same as that of the auxiliary composite wire of (2).

The cross-sectional shape of the auxiliary composite wire may be any of circular, elliptical, polygonal (triangular, quadrangular, etc.), as long as it is a particle having a powdery flux and / or a blowhole improving element inside. Alternatively, a metal layer that covers the outer skin or the outside may be folded inside.

FIG. 1 is a perspective view showing an example of an embodiment of a welding method of the present invention. 1, 2 are materials to be welded, 3 is a welding torch, and 8 is a welding torch.
Is a welding bead, and 10 is a shielding gas. As a method of supplying the blowhole improving element into the arc and / or the molten pool using the auxiliary composite wire, as shown in FIG. 1, in the consumable electrode type gas shield arc welding, the arc 6 generated from the welding wire 4 and / Or molten pool 7
The auxiliary composite wire 5 may be supplied to the auxiliary composite wire 5 via the supply nozzle 9. This supply rate may be appropriately set according to the arc welding conditions (welding current, voltage). Further, if the auxiliary composite wire 5 is introduced into the molten pool 7 and the auxiliary composite wire 5 is melted by the heat of fusion, the blowhole improving effect can be advantageously obtained. Further, if the auxiliary composite wire 5 is melted in the vicinity of the root portion of fillet welding, the effect of preventing the intrusion of zinc gas described above will work more advantageously.

As the above-mentioned supply nozzle, a general arc welding wire feeder may be used. Further, when the welding wire and the auxiliary composite wire are supplied in conjunction with each other, the generation of blow holes can be prevented more effectively.

The galvanized steel sheet to which the welding method of the present invention is applied includes various manufacturing methods such as a hot dip coating method, an electroplating method, a vapor deposition plating method and a thermal spraying method. The plating composition is pure Zn. Other than Zn, Fe, Z
n and Ni, Zn and Al, comprise one or two or more kinds of alloy elements and impurity elements for the improvement of corrosion resistance such as various functions mainly of Zn such as Zn and Mn, also SiO _2, A
There are ceramic fine particles such as l ₂ O ₃ and the like, oxides such as TiO ₂ and organic polymers dispersed in the plating.
In addition, the composition is a single composition in the thickness direction of the plating layer, or the composition changes continuously or in a layered manner.
Some include various alloy elements.

For example, hot-dip galvanized steel sheet, iron-zinc alloyed hot-dip galvanized steel sheet, aluminum mainly containing zinc, hot-dip galvanized steel sheet of iron or the like, alloyed hot-dip in which the lower layer is alloyed in the cross-sectional direction of the plating layer. Galvanized steel sheet (generally referred to as half alloy), one-sided iron-zinc alloyed hot-dip galvanized layer, galvanized steel sheet consisting of other-side hot-dip galvanized layer, zinc, iron by electroplating, vapor deposition plating, etc. on these plating layers, Steel plate plated with a metal containing nickel as a main component, or electrogalvanized steel plate, zinc, nickel, chromium alloy electroplated steel, etc., and a single alloy layer or multi-layer alloy electroplated steel plate, and these plated layers There are a plated steel sheet coated with an organic film, a vapor-deposited steel sheet of zinc and a metal containing zinc, and the like. Others, SiO ₂ , A
There is a dispersion-plated steel sheet in which fine ceramic particles such as l ₂ O ₃ and TiO ₂ and an organic polymer are dispersed in zinc or zinc alloy plating. The present inventors have confirmed that the above-mentioned effects are produced regardless of the type of galvanized steel sheet.

The gas shielded arc welding to which the present invention is applied may be any welding method as long as it is gas shielded. For example, there are a MAG welding method using a solid wire and a cored wire, a MIG welding method, a TIG welding method and a plasma welding method.

[0020]

[Examples] Welding tests were conducted on various galvanized steel sheets shown in Table 1 to examine the occurrence of blowholes. As shown in Fig. 1, the welding method is two-piece fillet welding,
A welding current was used so that the penetration on the lower plate side of the stack was 35% of the plate thickness. The welding speed was 1200 mm / min, the main wire for arc welding was a solid wire having a diameter of 1.2 mm, and the auxiliary composite wire having various components and different wire diameters was used. The shielding gas is Ar8.
Three kinds of 0% + CO ₂ 20%, CO ₂ and He were used, and the flow rate was 25 liters / min in all cases. As shown in FIG. 1, automatic welding was employed in which the welding position was horizontal, the torch angle was 60 ° from the horizontal, and the torch advance angle was 0 °.

[0021]

[Table 1]

For the evaluation of the number of defects, all blowholes were detected by X-ray transmission test of all weld bead lines, and 10
The number of blow holes per 0 mm length was evaluated. These welding conditions and evaluation results are shown in Tables 2 to 10.

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

[0026]

[Table 5]

[0027]

[Table 6]

[0028]

[Table 7]

[0029]

[Table 8]

[0030]

[Table 9]

[0031]

[Table 10]

The main component of the flux of the auxiliary composite wires of Tables 2 to 4 (Examples A1 to A36, Comparative Examples A37 to A45) is that "Wire 1" is an oxide such as TiO ₂ or MgO.
“Wire 2” is a fluoride such as CaF ₂ or BaF ₂ , and “wire 3” is an oxide such as TiO ₂ , SiO ₂ or Zr ₂ O ₃ .

The composition of the metal layer coating the outside of the auxiliary composite wires of Tables 5 to 7 (Examples B1 to B39, Comparative Examples B40 to B48) and the flux main component were "wire 4".
Is weight% (the same applies to other wires below) C = 0.05, S
i = 0.60, Mn = 0.43, S <0.01, P <
0.01, the balance Fe and an unavoidable impurity as an outer layer, and an auxiliary composite wire containing TiO ₂ as a main component of the flux. “Wire 5” has C = 0.06, Si =
0.25, Mn = 0.23, S <0.01, P <0.0
1, Nb = 0.83, Ti = 0.008, steel consisting of balance Fe and unavoidable impurities as an outer layer, and CaF ₂ , B
Auxiliary composite wire whose main component is aF ₂ isofluoride is shown. "Wire 6" has C = 0.05,
Si = 0.60, Mn = 0.43, S <0.01, P <
An auxiliary composite wire having 0.01 as the outer layer and steel as a balance Fe and unavoidable impurities and having a reduced slag-forming agent and a metal powder as a main component of the flux is shown.

Tables 8 to 10 (Examples C1 to C39,
The outer layers of the auxiliary composite wires of Comparative Examples C40 to C48 are “wire 7” in which C = 0.05, Si = 0.60, Mn = 0.
43, S <0.01, P <0.01, the balance Fe and unavoidable impurities, and the “wire 8” has C =
0.06, Si = 0.25, Mn = 0.23, S <0.
01, P <0.01, Nb = 0.83, Ti = 0.00
8. Steel consisting of balance Fe and unavoidable impurities,
“Wire 9” has C = 0.002, Si = 0.41, Mn
= 0.35, S <0.01, P <0.01, Nb = 0.
015, Ti = 0.008, N = 0.0035, balance F
Steel consisting of e and unavoidable impurities, "Wire 1
“0” is steel consisting of Fe and the balance being unavoidable impurities.
The “wire 11” is composed of Cu and the balance is unavoidable impurities.

According to the present invention, the occurrence of blowholes during gas shield arc welding of galvanized steel sheets can be significantly reduced, and the reliability of the joint can be greatly improved. Moreover, Cr, V, B, Ti,
Unlike the case of containing Ta, W or P, there is no fear of degrading the mechanical properties of the steel sheet and the yield of the above elements is good, so that it is far superior in terms of use performance and cost. Therefore, the present invention, as a gas shielded arc welding method of galvanized steel sheet having excellent arc weldability and an auxiliary composite wire, greatly contributes to industrial development.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a welding method of the present invention.

[Explanation of symbols]

 1, 2 Material to be welded 3 Welding torch 4 Welding wire 5 Auxiliary wire 6 Arc 7 Welding pool 8 Welding bead 9 Supply nozzle 10 Shielding gas

Claims (3)

[Claims] 1. When supplying a blowhole improving element into an arc and / or a molten pool by an auxiliary composite wire having a composition different from that of a welding wire in the case of gas shielded arc welding of a galvanized steel sheet, a group of blowhole improving elements is provided. It contains one or more of Cr, V, B, Ti, Ta, W, P and Fe, and the total content of the above elements is 10% or more based on the weight of the wire excluding flux, and the balance is unavoidable. Auxiliary composite wire for gas shielded arc welding of galvanized steel sheet, characterized in that a flux is coated with an outer sheath made of mechanical impurities. 2. When a galvanized steel sheet is gas shielded by arc welding, when a blowhole improving element is supplied into an arc and / or a molten pool by an auxiliary composite wire having a composition different from that of a welding wire, a blowhole improving element group is provided. It contains one or more of Cr, V, B, Ti, Ta, W, P and Fe, and the total content of the elements is 10% to 90% based on the weight of the wire excluding the flux.
An auxiliary composite wire for gas shielded arc welding of galvanized steel sheet, characterized in that a mixture of particles and flux, the balance of which is unavoidable impurities, is coated with a metal plate. 3. When supplying a blowhole improving element into an arc and / or a molten pool by an auxiliary composite wire having a composition different from that of a welding wire in the case of gas shield arc welding a galvanized steel sheet, a group of blowhole improving elements is provided. It contains one or more of Cr, V, B, Ti, Ta, W, P and Fe, and the total content of the elements is 10% to 90% based on the weight of the wire excluding the flux.
An auxiliary composite wire for gas shielded arc welding of galvanized steel sheet, characterized in that particles having an inevitable impurity in the balance are coated with a metal plate.