JPS60257993A - Cored wire for gas shielded arc welding - Google Patents

Abstract

PURPOSE:To decrease the variance in a flux rate and to assure excellent welding workability by setting the fluidity of the metallic powder to be compounded into a filled flux to a specific value or below. CONSTITUTION:A cored wire for gas shielded arc welding is constituted by filling the powder flux contg. 85-99wt% metallic powder consisting essentially of iron powder and having <=81sec/50g (the value measured in accordance with JIS Z-2502) fluidity of the metallic powder into a steel sheath. The cored wire for gas shielded arc welding having the excellent welding efficiency and welding workability is thus obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a gas-shielded arc welding device that exhibits excellent welding efficiency and welding workability in automatic or semi-automatic welding for shipbuilding, steel frames, bridges, etc. It concerns composite wires.

[Conventional technology]

In recent years, in the welding construction of various structures such as ships and bridges, the use of gas shield door welding methods, which are advantageous in improving welding efficiency and promoting labor savings, has rapidly increased. ing. Wires used in this type of welding are broadly classified into (1) solid wires and (2) composite wires formed by filling a metal outer sheath with powdery granular flux. Among these, composite wires that contain a large amount of metal powder, mainly iron powder, as a flux component are commonly called iron powder-based composite wires, and have high welding efficiency because they can obtain the same amount of deposited metal as solid wires. ■As composite wire has the characteristic of providing excellent welding workability unique to composite wire, demand for it is expected to continue to increase in the future.

However, this type of iron powder-based composite wire has a problem in that the filling flux rate varies widely and welding workability (especially arc stability) is poor. Although the cause of these problems is not necessarily clear, it appears that the above problems cannot be avoided as long as a filling flux containing a large amount of metal powder is used. In order to deal with these inconveniences, various improvements have been made regarding, for example, the flux component, sheath component, dimensions of the metal sheath, flux filling method, wire drawing speed, die schedule, etc.

[Problem that the invention seeks to solve]

However, even with the above method, it is not possible to make the flux rate uniform to a satisfactory degree, and in the end, it is not possible to obtain sufficient welding workability. has become a major obstacle.

The present invention has been made in view of these circumstances, and its object is to provide an iron powder-based composite wire that has a uniform flux rate and can provide excellent welding workability.

[Means for solving problems]

The composite wire for gas shielded arc welding of the present invention contains 85 to 99% by weight of metal powder mainly composed of iron powder, and the fluidity of the metal powder is 81 seconds 150 y or less (JIS Z 25
The gist of this method is that a powdery flux having a measurement value of 0.02 is filled into a steel outer skin.

[Function] According to the results obtained by the present inventors in preliminary experiments, there is a certain correlation between the flux rate in the composite wire and the fluidity of the filling flux, and It was confirmed that the flux rate of the composite wire exhibited non-uniformity depending on the degree of poor fluidity. In addition, flux containing a large amount of metal powder, mainly iron powder, has extremely poor fluidity, and when the seam of the metal shell is sewn together by resistance welding, etc., the flow of electricity during welding causes problems. There are also circumstances in which the magnetic metal powder (iron powder, etc.) is affected by the action of the magnetic force, further deteriorating its fluidity, and this causes Form 1 to affect the entire filling flux, inhibiting the uniformity of the flux rate. It was confirmed that there is.

On the other hand, when we measured the fluidity (measured in accordance with JIS Z 2502; the same applies hereinafter) of metal powder used as a filling material for ordinary composite wire for welding, it was 38 to 8.
5 seconds and 150 y, and when such a filling flux containing a large amount of metal powder is used, the variation in flux 1j rate will be noticeable.

Therefore, we conducted an experiment from the viewpoint that it is necessary to clarify the relationship between the fluidity of metal powder and the variation in flux rate, and thereby to understand the fluidity that can increase the uniformity of flux rate to a satisfactory degree. .

That is, a powder flux having the composition shown in Table 1 was prepared (however, multiple types of metal powder with different flow rates were used), and ordinary composite wires C1 and C2 using mild steel as the metal sheath were prepared. φ, flux rate - flux weight / (shell weight flux weight) ((turn) is approximately 18%
80 samples (20 cm) were taken at 1 m intervals in the longitudinal direction to examine variations in flux rate. The fluidity of the flux components other than the metal powder was 150y for 25 to 28 seconds.

Table 1 (% by weight) The results are shown in FIG. The black dots in the figure indicate welding workability (
Indicates that the arc stability) was poor.

As is clear from Figure 1, the dispersion of flux rate becomes larger when metal powder with higher fluidity (lower fluidity) is used, and welding workability tends to deteriorate accordingly. The above-mentioned dispersion increases rapidly when the degree is around 81 seconds and 150 y. The points marked with ◎ in the figure are titania-based (metal powder content: 15*
) This shows the above-mentioned variation when filling flux, and the variation when using metal powder with a flow rate of 81 seconds 150y or less can be suppressed to the same level as when using the titania-based filling flux. , it is possible to obtain a composite wire with no practical problems in terms of arc stability. Furthermore, as is clear from FIG. 1, the lower the fluidity of the metal powder, the less variation in flux rate, so the lower the fluidity is, the better.

In this way, in the present invention, the filling rate of the flux can be made as uniform as possible by adjusting only the fluidity of the metal powder in the filling flux, and the fluidity of the flux components other than the metal powder is almost the same. However, it is not a problem. However, in the present invention, as described above or as will be detailed later, metal powder is used in the flux component at least 85 to 99% by weight, and conventional metal powder generally has poor fluidity (as described above). Coupled with the fluidity (88-85 seconds 150y) and the fact that it is susceptible to the influence of magnetic force, it is safe to assume that most of the causes of increased flux rate variation depend on the fluidity of the metal powder. . On the other hand, other flux components (metal oxides, metal fluorides, metal carbonates, etc.) inherently have excellent fluidity, and as seen in the titania-based composite wire mentioned above, the variation in flux rate can be reduced. Since this is not a factor, it is considered that by regulating the fluidity of the metal powder as described above, the fluidity of the entire filling flux can be sufficiently increased.

As mentioned above, the metal powder used in the present invention is mainly composed of iron powder (approximately 50 to 90% by weight of the total metal powder), and other metal powders include Mns S 1 % A I, Ti,
Deoxidizing metal powder such as Mg and these iron alloys, Nis C
Although alloy components such as r- and Mo are included, the proportion of metal powder including iron in the total filling flux must be set in the range of 85 to 99% by weight. The reason for this is that if the content of metal powder is less than 85% by weight, the effect of improving welding efficiency, which is a characteristic of so-called iron-based composite wires, cannot be sufficiently achieved, and in this case, metal oxidation with good fluidity cannot be achieved. Because the content of metal powder is high, the fluidity inhibiting effect of metal powder does not appear as much, and even when using metal powder with poor fluidity, it is possible to obtain a sufficiently uniform flux rate. This is because the meaning of regulating the flow rate would be virtually unrecognized. On the other hand, if the metal powder content exceeds 99%, slag formation in the filling flux (various metal oxides, etc.) will occur.

The absolute amount of arc stabilizer (K2TiO3, etc.) becomes insufficient, and the bead shape deteriorates due to insufficient amount of slag produced, or spatter increases due to arc instability, reducing work efficiency. However, if the upper limit of the metal powder is set at 99% by weight, a sufficient amount of slag forming agent etc. can be included as the remaining component, so problems such as spatter generation due to arc instability and deterioration of bead shape can be avoided. Therefore, it is possible to obtain an iron powder-based composite wire that exhibits a high level of welding efficiency. Note that the iron content in the metal powder is preferably 60% by weight or more, more preferably 70% by weight or more, considering the purpose of "increasing the amount of welded metal." In this case, the iron content in the ferroalloy is The iron content may also be included in the calculation.

Next, the form of the composite wire is not particularly limited, but it is preferably a seamless type, and the method for manufacturing it is: ■ After filling the above-mentioned powder flux into a pipe-shaped metal jacket, it is made into a predetermined cross-sectional size. A method of wire drawing until the end of the wire is drawn, and a method of wire drawing after bending a band-shaped metal sheath into a pipe shape, filling the inner cavity with the above-mentioned granular flux, and seam welding the abutting portions of both sides by resistance welding, etc. One method is to do so. However, since the composite wire obtained by the above manufacturing method has no gaps in the longitudinal direction of the outer skin and has a nearly symmetrical cross section, there is no directionality in the bending direction, and the wire feedability and straightness are improved. This is because it has good properties and can be subjected to copper plating treatment for preventing rust or improving conductivity and feedability without any problem. In particular, in the present invention, as mentioned above, the flux containing a large amount of metal powder is filled to improve welding efficiency. is applied, so the above-mentioned effect can be achieved by making it a seamless composite wire! ! The signs will be extremely significant. When applying metal plating such as copper plating, the preferred amount of plating is in the range of 0.05 to 0.80% based on the total weight of the composite wire, and if it exceeds 0.80%, the effect of improving the melting rate will be inhibited. In addition, care should be taken because the amount of plating metal mixed into the weld metal may increase and impair the physical properties of the weld metal.

The target steel types for which the composite wire of the present invention is used are mainly mild steel and high-strength steel, but it can of course also be applied to welding other materials such as low-alloy steel and high-alloy steel. The type of metal powder to be mixed may be appropriately selected depending on the type of steel to be welded as described above. Carbon dioxide is the most common shielding gas, but Ar and H
Of course, it is also possible to use gas or a mixture thereof.

〔Example〕

Using the filling flux having the composition shown in Table 2 and a mild steel outer skin material, the flux was filled so that the target flux rate was about 18% by weight, and then wire drawing was performed using a conventional method.1.2. , φ were prepared, and the stability of flux rate, welding workability, and welding efficiency of each composite wire were investigated using the following method.

[Stability of flux rate]

80 samples (2
0crn) and measure the individual flux rates to correct for variations.

○: Variation less than 2% ×: Variation 2% or more [welding workability, welding efficiency] Welding posture - downward welding method: Automatic welding (continuous 2-pass welding) Groove conditions:
V-groove welding current: 260-850A Shielding gas: CO7,201/denominator Material: Mild steel Judgment: ○...Good, △...Slightly good, ×...Poor The results are shown in Table 8.

4. Bow mail :・ Table 8 From Table 2.8, the following can be considered.

Experiments No. 001 to 1O are examples that satisfy the specified requirements of the present invention, have excellent uniformity with little variation in flux rate, and have extremely good welding workability and welding efficiency.

On the other hand, Experiments Nos. 11 to 14 are comparative examples that lack any of the requirements stipulated by the present invention, and as shown below, any of the variations in flux rate, welding workability, and welding efficiency were poor.

Experiment No. 11.14: This is a comparative example in which the fluidity of the metal powder is too high, and the flux rate varies widely, resulting in poor welding workability.

Experiment No. 12: This is a comparative example in which the content of metal powder is too high, and the bead appearance (shape) is poor and an increase in spatter is observed because the amount of slag forming agent and arc stabilizer in the filled fluff is insufficient. It will be done.

Experiment No. 18: This is a comparative example where the content of metal powder is insufficient, and the fluidity of the entire filling flux is good and there is little variation in flux rate, and the welding workability is good, but the welding efficiency is poor and the iron powder-based composite The original characteristics of the wire cannot be enjoyed.

〔Effect of the invention〕

The present invention is constructed as described above, but the point is that by setting the fluidity of the metal powder mixed in a large amount in the filling flux to a specific value or less, the flow of the flux is particularly improved during filling. The variation in the welding rate was drastically reduced, the deterioration of arc stability caused by the variation was prevented, and excellent welding workability was ensured. As a result, the biggest drawback of iron powder-based composite wire has been resolved, and its features (excellent welding efficiency) can be fully demonstrated, and the range of application of iron powder-based composite wire can be greatly expanded. Became. In addition, especially for seamless composite wires, manufacturing requirements require a large reduction in area during wire drawing, and under these conditions, uneven flux rates can lead to wire breakage during wire drawing. However, the present invention has the advantage that the flux rate can be made uniform during filling, so there are fewer disconnection accidents, and productivity can be improved.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the fluidity in the filling flux and the variation in flux rate.

Claims (1)

[Claims] Contains 85 to 99% by weight of metal powder mainly composed of iron powder, and the fluidity of the metal powder is 81 seconds and 150 y or less (JIS Z
1. A composite wire for gas-shielded arc welding, characterized in that the copper outer sheath is filled with a powdery flux having a measurement value according to 2502.