JPH0751890A - Gas shielded arc welding titania flux cored wire - Google Patents

Abstract

PURPOSE:To provide a gas shielded arc welding titania flux cored wire which is particularly small in the amt. of the fumes to be generated. CONSTITUTION:This gas shielded arc welding titania flux cored wire is formed by filling a flux into a steel sheath and is the gas shielded arc welding titania flux cored wire formed by filling the flux contg., by weight% with the total flux, 8 to 60% TiO2, 0.01 to 1.0% Cs (where 20 to 2000 ratio of TiO2/Cs) <=0.5% C into the steel sheath at 5 to 30% of total weight% of the wire. The chemical components of the steel sheath are preferably <=0.02% C and <=0.20% Ti in the ratio with total weight of the sheath.

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 shield arc welded titania-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 wire is rapidly expanding due to the ease and efficiency of welding. In particular, titania-based flux-cored wire has a small amount of spatter, has a good bead appearance, and is easy to weld in all positions, so it is important to see how it penetrates into fields such as shipbuilding and bridges. There is something to watch.

On the other hand, however, the shortage of welding technicians is serious. This is probably because the welding work environment is harsh compared to other production sites due to welding fumes and spatter.

An object of the present invention is to provide a gas shielded arc welding titania type flux-cored wire which produces a small amount of fumes in view of these situations.

[0005]

As a technique for reducing welding fume, it is known that reducing the amount of C and oxygen in the wire is effective. The present inventors have completed the present invention as a result of earnestly researching a titania-based flux-cored wire that can further reduce the amount of fumes generated.

That is, the present invention relates to a gas shielded arc welding titania type flux cored wire obtained by filling a steel shell with a flux, based on the total weight% of the flux.
_{In, TiO 2: 8~60%, Cs} : 0.01~1.0%,
(However, the ratio of TiO ₂ / Cs: 20 to 2000) C ≦ 0.5
% Of the total amount of the wire in the steel outer shell, the gas shielded arc welded titania-based flux-cored wire is featured.

According to another aspect of the present invention, the chemical composition of the steel shell is C: 0.02% or less, based on the total weight of the shell.
Moreover, Ti is characterized by being 0.20% or less.

[0008]

The present invention will be described in more detail below. First, an example of basic experiment results showing the outline of the results of various experiments leading to the present invention will be shown.

In order to reduce the fume generation amount of the flux-cored wire, the flux of various compositions is combined with the steel skin of various compositions to produce the flux-cored wire having a diameter of 1.2 mm, and the fume generation effect is reduced. According to JIS Z39
It was examined by a test based on 30.

The welding conditions are as follows. (Welding conditions) Welding method: Downward bead-on-plate welding Welding current: 300A Arc voltage: Appropriate voltage with arc length of 1.5-2.0mm Welding speed: 30cm / min Wire protrusion length: 25mm Polarity: DCEP Shielding gas: 100% CO ₂ (flow rate 25 liters / min) Test plate: JIS G3106 SM490A (plate thickness 1
2 mm)

As shown in FIG. 1 to FIG. 4, the results of the welding test show that, as a controlling factor for reducing the fume generation amount of the titania-based flux-cored wire, it is C from the flux side.
The amount, the amount of Cs, and the ratio of TiO ₂ / Cs are important, and it has been recognized that the amounts of C and Ti are important from the viewpoint of the chemical composition of the steel shell. Note that the present inventors have an effect on reducing the fume generation amount of the titania-based flux-cored wire by using only one of the chemical components of the flux surface and the steel outer surface, but by combining both, the effect is further enhanced. I also determined that it stands out.

Based on the above experimental results, the reasons for limiting the chemical composition of the flux and the steel shell in the flux-cored wire of the present invention completed will be explained. The flux component is the total weight% of the flux, and the outer skin component is the total weight% of the outer skin.

First, the reasons for limiting the components of the flux are shown below.

C ≦ 0.5% C is used as a deoxidizing agent and, if necessary, for the purpose of securing toughness by improving strength and hardenability, and improving penetration depth by promoting arc concentration. It is added while considering the amount of C therein. In that case, when the amount exceeds 0.5%, the fume generation amount remarkably increases and the spatter generation amount also increases (FIG. 1). It is considered that this is because the explosive generation of CO and CO ₂ , which are the sources of fumes generated as a result of the reaction between C and oxygen, becomes significant at 0.5% or more. Therefore, the amount of C in the flux is regulated to 0.5% or less.

Cs: 0.01 to 1.0% Although the mechanism by which Cs reduces the amount of fumes generated is not clear in detail, Cs lowers the potential gradient of the arc and improves the stability of the arc. This is considered to be one of the reasons. The effect of reducing the amount of fume generated by adding Cs is as shown in FIG.
If the amount of Cs is less than 0.01%, the effect of fume reduction is not recognized, while if it exceeds 1.0%, spatter rather increases, and the moisture absorption of the flux becomes remarkable and the amount of hydrogen in the weld metal increases. As a result, its soundness and crack resistance deteriorate. Therefore, the amount of Cs in the flux is 0.01-1.0%
And

Cs sources include complex oxides with CsCO ₃ or SiO ₂ and natural porusite ores,
It may be added in the form of a simple salt or a double salt resulting from the synthesis.
However, if these Cs sources are added in amounts exceeding 1.0% in terms of Cs, the welding workability becomes poor.

TiO ₂ : 8 to 60% TiO ₂ can be expected to act as a slag forming agent / arc stabilizer. The amount of TiO ₂ must be at least 8% or more in order to obtain a good bead appearance / shape and an effect of improving arc stability in the downward and horizontal postures. But T
When iO ₂ exceeds 60%, the freezing point of the slag is high and the viscosity becomes excessive, so that slag entrainment and gas defects on the bead surface are likely to occur. Therefore, the amount of TiO ₂ in the flux is in the range of 8-60%.

As the TiO ₂ source, oxides such as rutile, reduced illuminant, rucoxin, illuminant, potassium titanate and the like can be mentioned.

Ratio of TiO ₂ / Cs: 20 to 2000 The effects of adding TiO ₂ and Cs alone are as described above, but it was found that the effects of both effects the respective addition amounts. That is, the ratio of TiO ₂ / Cs is also the amount of fume generated, sagging in the vertical advance welding, and X of the weld metal
It has a great influence on the wire performance (fusion failure, slag winding defect, etc.) (Fig. 3). In order to obtain good welding workability in all positions and to obtain a sound weld metal, the ratio T
It is necessary that iO ₂ / Cs is at least 20 or more. However, if the ratio exceeds 2000, the fume reducing effect of Cs becomes small, and the X-ray performance of the weld metal deteriorates. Therefore, it is necessary to suppress it to 2000 or less.

Compounds of alkali metals other than Cs such as Li, Na and K can be added in appropriate amounts, if necessary. These alkali metal compounds other than Cs are extremely effective in improving the arc stability and reducing the amount of spatter, but they are a significant source of fumes. That is, these alkali metal fluorides, carbonates, and simple oxides such as Na ₂ O, K ₂ O, and Li ₂ O are prominent sources of fumes, and are complex oxides with other oxides. However, there is no difference in the extent to which the fumes are generated. Therefore, it is preferable that the addition amount of the alkali metal compound other than Cs is suppressed to 7.0% or less in terms of the metal element.

Needless to say, the flux may contain other components that are usually added as a titania-based flux-cored wire.

Next, the reasons for limiting the chemical composition of the steel shell will be described below.

C ≦ 0.02%, Ti ≦ 0.20% C causes explosive production of CO and CO ₂ , which are fume sources resulting from the reaction with oxygen, as in the case of flux. Further, since the influence of C on the outer skin on fumes and spatter is more remarkable than that by the flux, it is necessary to keep the content thereof as low as possible. It should be limited to 0.02% or less even in consideration of processability in production and decarburization technology.

Since Ti has a strong affinity with oxygen and produces a high freezing point oxide, an oxide film is formed on the surface of the suspended droplet at the tip of the wire in the arc welding process, and fumes are generated as a result of the reaction between C and oxygen. Source CO, CO ₂
However, excessive addition of Ti causes deterioration of the material such as reduction of ductility and hardening. Therefore, the Ti amount is 0.
The range is 20% or less (see FIG. 4).

Regarding the range of the amount of C and the amount of Ti in the steel shell, either one of the restrictions is effective in reducing the fume generation amount, but by restricting both components within the above range at the same time, The effect will be much greater.

Regarding other components, it is desirable that Mn is in the range of 0.10 to 0.70% and Si≤0.35% in consideration of the workability in the rolling or / and drawing process in wire production.

The reason for limiting the flux ratio of the flux-cored wire (based on the total weight% of the wire) is as follows.

Flux rate: 5 to 30% Usually, the flux rate should be determined in combination with the wire cross-sectional shape in view of the uniformity in wire melting and wire workability, and low flux for thin wires. It is desirable to have a simple cross section at a high rate, and for large diameter wires, a high flux rate and a complex cross section. However, in any case, if the flux rate is less than 5%, large-sized spatters increase, and
If it exceeds 0%, the outer skin becomes thin, and there is a problem that the wire feedability is deteriorated. Therefore, the flux rate is 5 to 3
Specify as 0%.

The wire cross-sectional shape is not limited in any way, and various shapes such as those shown in FIGS. 5A, 5B, 5C and 5D can be used. Further, the surface of the wire may be plated with Cu, Al or the like, in which case the plating amount is preferably 0.05 to 0.35%. Further, the wire diameter can be arbitrarily determined according to the application.

Further, as the shield gas, oxidizing, neutral and reducing gases can be applied. As a general shield gas, CO ₂ gas or a mixed gas of two or more kinds of Ar, CO ₂ , O ₂ , He and the like can be used.

Further, although the base steel type to which the flux-cored wire of the present invention is applied is mainly mild steel / high tensile steel, it may be applied to other steel types such as low alloy steel and high alloy steel depending on the application.

Next, examples of the present invention will be described.

【Example】

Using a steel hoop containing the components shown in Table 1, a flux containing wire containing the components shown in the same table was filled at a predetermined flux rate (1.
2mmφ) was manufactured. Then, a welding test was performed using this flux-cored wire. The welding conditions are the same as the basic experimental conditions described above.

As shown in Table 1, the test results show that in all the examples of the present invention, the amount of fume generated was extremely small, and the workability (spatter generation amount, bead sag, X-ray performance, bead appearance, etc.) was excellent. ing. On the other hand, in the comparative examples, the amount of fumes generated is large, and there are many cases in which there is a problem in welding workability.

In Table 1, No. 1 to No. 6 are the effects of the amount of TiO ₂ in the flux, No. 7 to No. 11 are the effects of the amount of Cs in the flux, and No. 12 to No. 13 are Effect of C content in flux, No.14 to No.17 is T in flux
iO ₂ of impacts, Nanba18～nanba21 the influence of the flux rate, Nanba22～nanba23 are those examined principally from the effects of C content and Ti content in the steel sheath, these Some of the test results are shown in FIGS.

[0036]

[Table 1]

[0037]

As described in detail above, according to the present invention,
In particular, it is possible to provide a gas shielded arc welding titania-based flux-cored wire in which the amount of fumes generated is significantly reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the amount of C in a flux and the amount of fumes generated.

FIG. 2 is a diagram showing the relationship between the amount of Cs in the flux and the amount of fume generated.

FIG. 3 is a diagram showing a relationship between a TiO ₂ / Cs ratio in a flux and a fume generation amount.

FIG. 4 is a diagram showing the relationship between the amount of fumes and the amount of C and Ti in the steel shell.

5A to 5D are diagrams showing an example of a cross-sectional shape of a flux-cored wire (M: steel outer shell, F: flux).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeo Nagaoka 100-1 Urakawachi Fujimae, Fujisawa-shi, Kanagawa Kobe Steel Fujisawa Works (72) Inventor Koichi Hosoi 100-back Urakawachi, Fujisawa, Kanagawa 1 Stock Company Kobe Steel Works, Fujisawa Works

Claims (2)

[Claims] 1. A gas shielded arc welding titania-based flux cored wire formed by filling the flux in the steel sheath, in pairs flux total _{weight%, TiO 2: 8~60%,} Cs: 0.01~1.0 % (However, the ratio of TiO ₂ / Cs: 20-2000) C ≦ 0.5%, the total weight% of the wire in the steel shell is
A gas-shielded arc-welded titania-based flux-cored wire, which is filled with 5 to 30% by weight. 2. The chemical composition of the steel shell is C: 0.02% or less and Ti: 0.20%, based on the total weight of the shell.
The gas shielded arc welding titania-based flux-cored wire according to claim 1, wherein: