JP3197404B2 - Flux-cored wire for gas shielded arc welding - 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 for welding, and more particularly to a flux cored wire for gas shielded arc welding having excellent welding workability.

[0002]

2. Description of the Related Art Flux-cored wires for gas shielded arc welding (hereinafter referred to as flux-cored wires) are mainly used for automatic or semi-automatic welding of mild steel and low alloy steel. And the weld bead is completely encapsulated by the generated slag, and thus has advantages such as a beautiful appearance. Therefore, it has tended to be used more and more in recent years.

Conventionally, a flux-cored wire is shown in FIG.
However, when the diameter is reduced to 2.4 mm or less, the wire is easily broken at the time of wire drawing, and processing is difficult. In addition, since the amount of use of the flux-cored wire having a small diameter has increased, recently, it is easy to draw as shown in FIG.
A flux-cored wire having a simple sectional structure shown in (c) is mainly manufactured.

However, in the case of a flux-cored wire having a simple cross-sectional structure, the outer shell melts quickly during welding, and the melting of the filling flux is delayed, so that the unmelted flux tends to protrude.
There are problems such as the occurrence of welding defects such as slag entrainment in the welded portion and the occurrence of spatter due to unstable arc.

In order to solve this problem, for example, Japanese Patent Application Laid-Open
JP-A-8-148095 discloses a technique in which a carbonate of Li is contained to lower the melting point of the filling flux and increase the melting rate of the filling flux. In addition, Japanese Unexamined Patent Publication
Japanese Patent Application Laid-Open No. -104695 discloses that metal powder is segregated in the direction of the cross section of the wire and a part of the metal powder is distributed so as to be in contact with the inner surface of the outer cover. Is disclosed.

[0006]

However, recently, there has been a trend toward adopting welding conditions having a higher current density than efficiency.
Even if the projecting of unfused flux is improved by the above-mentioned prior art, the technique described in Japanese Patent Application Laid-Open No. 58-148095, in which the melting point of the filling flux is lowered by adding a carbonate of Li, still protrudes the unmolten flux. Is generated, and the arc may become unstable and spatter may occur. Further, in the technique described in Japanese Patent Application Laid-Open No. 62-104695 in which metal powder is segregated in the direction of the cross section of the wire and a part of the metal powder is distributed so as to be in contact with the inner surface of the outer coat, the unmelted flux does not protrude, but the metal powder is formed. In some cases, the arc generated from the gas becomes unstable and spatter occurs.

Accordingly, the present invention is directed to a gas shielded arc welding method having good welding workability, such as no projection of unmelted flux during welding, stable arcing and a small amount of spatter even under high current density welding conditions. An object is to provide a flux cored wire.

[0008]

The flux-cored wire for gas shielded arc welding according to the present invention contains 5 to 30% by weight of iron powder in the filling flux, and the other contains a deoxidizing agent,
A flux comprising an alloying agent, an arc stabilizer, and a slag forming agent is filled in a wire weight ratio of 12 to 22%, and the iron powder is filled in a central portion of a wire cross section.

[0009]

[Function] Since the iron powder is filled in the center of the wire cross section, even under high current density welding conditions, there is no protrusion of unmelted flux, the arc is stable, and the amount of spatter generated is reduced. The property becomes good.

[0010] 5-30% by weight of iron powder at the center of the wire section
Needs to be If the iron powder content is less than 5%, the unmelted flux will protrude under high current density welding conditions even if it is filled in the center of the wire cross section, causing slag entrainment in the weld or arcing. It becomes unstable and the amount of spatters increases. If the iron powder content exceeds 30%, the unmelted flux does not protrude and the arc is stable, but the generated slag is small and the weld bead is not completely encapsulated, resulting in poor bead appearance.

The filling rate of the flux composed of iron powder, deoxidizer, alloying agent, arc stabilizer and slag forming agent must be 12 to 22% by weight of the wire. If this is less than 12%, the arc becomes unstable and spatter occurs. Further, the generated slag amount is small and the weld bead is not completely covered, so that the bead appearance becomes poor. Conversely, if the flux filling rate exceeds 22%, the outer skin thickness becomes thin and the wire is easily broken at the time of wire drawing, making processing difficult.

The deoxidizing agent referred to in the present invention is Fe-S
i, Fe-Mn and the like; alloying agents refer to Ni, Mo and the like. The arc stabilizer is an alkali metal compound, and the slag forming agent is TiO ₂ , SiO ₂ , Al
Oxides such as ₂ O ₃ and CaO and CaF ₂ and Ba
It refers to F _2, AlF _3.

[0013]

The present invention will be described in more detail with reference to the following examples. First, two kinds of filling base fluxes shown in Table 1 were produced as trials. Various combinations of the base flux and the iron powder to be filled shown in Table 2 were used, and the base flux 2 and the iron powder 3 were supplied while the steel strip (skin) 1 was formed into a tube using the apparatus shown in FIG. . In FIG. 3, 1 is a shell (strip), 2 is a base flux, 3 is iron powder, and iron powder 3 is supplied so as to be wrapped in the base flux 2. FIG. 1 shows a cross section of the prototype flux-cored wire.

The strip 1 is 2.0 mm thick and 64 mm wide (SPH).
After supplying the base flux 2 and the iron powder 3 by using C), the opposite edge surfaces (not shown) are welded and subjected to one-time annealing by a rolling roll group to reduce the outer diameter to 3.0 mm. It was plated and wound on a coil. Then, the wire was finish-drawn and wound on a spool as a flux-cored wire of 1.2 to 1.6 mm.

The prototype wire wound on the spool was subjected to horizontal fillet welding to steel grade SM490B and a plate thickness of 12.7 mm, and the presence or absence of protrusion of unmelted flux, the measurement of spatter generation, and the bead appearance were examined. Table 3 shows the welding conditions. Table 2 summarizes the results.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

No. in the table. 1 to 6 are examples of the present invention.
o. 7 to 12 are comparative examples. No. satisfying all the constituent requirements of the present invention. Nos. 1 to 6 have no protrusion of unmelted flux, have stable arc, and generate 3 g of spatter.
/ min or less, the bead appearance was good, and the results were extremely satisfactory.

In the comparative examples, No. No. 7 has a small amount of iron powder at the center of the wire. No. 11 was prepared by mixing iron powder with a base flux and filling the mixture. Since No. 12 was not filled with iron powder, unmelted flux protruded in any case, the arc became unstable, and the amount of spatter generated frequently was 3 g / min or more. No. No. 8 had a large amount of iron powder, so there was no protrusion of unmelted flux, the arc was stable, and the amount of spatter generated was small. However, the amount of generated slag was small, so that the weld bead could not be completely covered and the bead appearance was poor. It became bad. No. In No. 9, since the flux filling rate was low, the arc became unstable, the amount of spatter generated was increased to 3 g / min or more, and the amount of slag generated was small, so that the weld bead could not be completely covered and the bead appearance was poor.
No. Since No. 10 had a high flux filling rate, the wire was disconnected at the time of drawing, and the welding test was stopped.

[0021]

As described above in detail, according to the flux-cored wire for gas shielded arc welding of the present invention, even under high current density welding conditions, unfused flux does not protrude during welding, and the arc is stable. Since a small amount of spatter is generated and a good bead appearance can be obtained, it greatly contributes to high efficiency of welding.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a flux-cored wire for gas shielded arc welding of the present invention.

FIGS. 2A, 2B and 2C are cross-sectional views showing a conventional flux-cored wire for gas shielded arc welding.

FIG. 3 is a perspective view showing an example of a flux supply method used in an embodiment of the present invention.

[Explanation of symbols]

 1 outer skin (strip) 2 base flux 3 iron powder

Continuation of front page (72) Inventor Kenji Shiiyama 4-2-1 Asae, Hikari-shi, Yamaguchi Prefecture Nippon Steel Welding Industry Co., Ltd. Inside the Hikari Factory (58) Field surveyed (Int. Cl. ⁷ , DB name) B23K 35 / 368 B23K 35/02

Claims (1)

(57) [Claims] 1. A flux-cored wire for arc welding, wherein the filler flux contains 5 to 30% by weight of iron powder, and the other contains a flux composed of a deoxidizing agent, an alloying agent, an arc stabilizer and a slag forming agent. 12 to 2 by weight
A flux-cored wire for gas shielded arc welding, wherein 2% is filled and said iron powder is filled in the center of the cross section of the wire.