JPH07251289A - Flux cored wire for arc welding and its production - Google Patents

Abstract

PURPOSE:To improve the plating adhesivity, the corrosion resistance, and the welding workability by providing the composite copper plating of the prescribed thickness on the outer skin surface by the electroplating and the chemical plating. CONSTITUTION:The copper plating of the film thickness of >=0.2mum by the electroplating is provided as the first layer on one side or both sides of a metallic strip. The copper plating of the film thickness of 0.2-10mum by the chemical plating is provided as the second layer. The metallic strip is bent in the U-shape with the surface having this composite copper plating layer being the outer side, and the flux is filled therein. The formation and wire drawing is made so that the thickness of the composite copper plating layer may be >=0.2mum in the final wire diameter. When the plating on the first layer is below the prescribed thickness, the performance is insufficient as the base plating, and cracks of the plating are likely to be generated. When the plating of the second layer is below the prescribed thickness, the oil for feeding can not be kept, and the wire feedability can not be secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a flux-cored wire for arc welding which is excellent in rust resistance and power feeding.

[0002]

2. Description of the Related Art Conventionally, it has been customary to apply copper plating to the surface of the wire for arc welding in order to improve rust resistance and power feeding. Has been done. Among the flux-cored wires, those of which the outer skin has no joints can be treated with a chemical solution because the flux is hermetically sealed in the pipe, and can be plated with copper.
However, since wires with joints are immersed in the plating solution during copper plating, chemicals enter the wires from the joints to deteriorate the flux, and the chemicals remaining inside the wires cause pits and blowholes during welding. There is a problem that welding defects such as occur. Therefore, it is difficult to apply copper plating to the flux-cored wire having joints. In order to solve this problem, in Japanese Patent Laid-Open No. 57-52595, a metal strip is plated with a single layer of copper, and this is filled with flux to perform molding and wire drawing.
We have a 6mmφ wire. In this case, bending is applied to the plated steel strip and the wire is drawn with a cold drawing die.Therefore, plating in a single layer is likely to cause peeling of the steel strip, resulting in unstable rust resistance and feedability. However, there is a problem that the workability is rather deteriorated as compared with the case where copper plating is not applied. That is, when the single layer plating is chemical plating, the adhesion of the plating is originally poor, and in the case of electroplating, the adhesion is good but the lubricity is poor.

In Japanese Patent Laid-Open No. 61-3697, a flux is filled in the inside, and after molding, the seam of the outer cover is welded and the surface is copper-plated. However, the cost of welding increases and the welding cost increases. However, there is a problem that the workability of welding of the product is deteriorated due to the alteration of the flux due to the heat effect of the above, and the fundamental problem has not been solved as a plating method for a wire having joints.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a flux-cored wire for arc welding and a method for manufacturing the same, which has been made to solve the above-mentioned drawbacks of the prior art.

[0005]

A first aspect of the present invention is a flux-cored wire for arc welding in which flux powder is placed in an outer shell formed by rolling a metal band, and electroplating is performed on the outer surface of the outer shell as a first layer. And a copper plating layer having a film thickness of 0.1 μm or more according to the above, and a copper plating layer having a film thickness of 0.1 to 5 μm formed by chemical plating as a second layer on the first layer. Is a flux-cored wire for arc welding, characterized in that the thickness is 0.2 μm or more. Copper plating is performed, and then the second layer is subjected to chemical plating as a second layer to a thickness of 0.2 to 10 μm. The surface having the composite copper plating layer is the outer surface, and the metal strip is U-shaped. Bend and fill this with flux, The thickness of the composite copper plating layer is a manufacturing method of a flux cored wire for arc welding, which comprises forming and wire drawing so as to be 0.2 [mu] m or more in diameter.

[0006]

The flux-cored wire for arc welding according to the present invention has a copper plating layer formed by electroplating on the first layer of the metal shell and a copper plating layer formed by chemical plating as the second layer.
It is filled with flux, molded and drawn.
The first electroplated copper plating layer can be applied thinly and evenly on the wire surface, and because it is not porous like the chemical plating layer, it has good adhesion to the base material and serves as a base plating. Are suitable. The film thickness is 0.
If the thickness is less than 1 μm, the thickness of the undercoating film is insufficient and the plating is liable to peel off, so the thickness must be 0.1 μm or more.

In order to obtain good feedability of welding wire, it is customary to apply feeding oil to the surface of the welding wire to reduce the wire resistance in the conduit tube. In order to hold the wire and stabilize the wire feeding property, the chemical plating which is porous is more suitable than the electroplating layer. Therefore, it was decided to carry out chemical plating on the electroplated layer having good adhesion.

If the film thickness of the second chemical plating layer is less than 0.1 μm, the porous film thickness is insufficient to retain the feed oil, and the wire feedability cannot be secured. .
On the other hand, if it exceeds 5 μm, the porous plating layer becomes too large,
It should be 0.1-5 μm because the peeling resistance deteriorates. As a result of applying these composite plating, processing during molding,
It was possible to obtain a good plating that does not peel off due to friction by a feeding roller during wire drawing and welding, and to maintain good feeding performance. The final plating thickness must be at least 0.2 μm or more to secure the rust resistance and power feeding of the wire.

Two-layer plating is carried out in order to prevent the plating from peeling off. Sufficient results can be obtained by plating at the stage of the metal strip before molding.
However, when the plating is performed after forming the U shape, the deformation after the filling is reduced, so that a better plating can be obtained.

[0010]

EXAMPLES Examples of the present invention will be described below. As shown in Fig. 1, remove the outer skin material (a) outer skin, (b) pickling,
(c) cleaning, (d) electroplating, (e) cleaning, (f) chemical plating, (g) cleaning and drying, (h) flux filling, (i) forming wire drawing, (j) finishing wire drawing, ( k) The product (l) was obtained through each winding process.

Width of JIS SPCC steel type 12.0 mm,
Using a 0.85 mm thick steel strip, the electroplating in the (d) process
The chemical plating in step (f) was performed under the conditions shown in Table 1. The plating thickness was adjusted by adjusting the linear velocity. The outer shell was filled with flux and formed into a 2.4 mmφ wire with a forming roll, and a 1.2 mmφ wire was manufactured with a cold drawing die. Flux filling rate is 15% per wire weight
So that Table 2 shows the results of the following various tests performed on the wire manufactured in this way.

[0012]

[Table 1]

[0013]

[Table 2]

Various evaluation methods are as follows. (1) Plating Adhesion It was wound on a 10 mmφ rod and the surface plating state was observed. The evaluation criteria are as follows. ◯: No peeling.

Δ: Plating cracks, peels off like a scaly, but does not peel off. X: Plating is peeled off. (2) Rust resistance The wire was kept in a thermo-hygrostat at 35 ° C and 90% RH for 36 hours, and the rusting condition was observed. The evaluation criteria are as follows.

◯: No rust was generated. Δ: A small amount of rust occurred. X: Innumerable spot rust or continuous rust occurred. (3) Weldability 280A, 31 on the base material JIS SM-400A (80mm × 400mm × 20mm)
Bead-on-plate welding was performed under the welding conditions of V ₂ , 40 cpm, and CO ₂ gas flow rate of 20 l / min, and the stability of the arc and the occurrence of spatter were observed. The evaluation criteria are as follows.

◯: Good Δ: Slightly good ×: Poor No. 1 to 4 are examples of the present invention, and Nos. 5 to 10 are comparative examples. In this example, good results were obtained in terms of plating adhesion, rust resistance and welding workability. On the other hand, in the comparative example, No. 5 has a poor first layer plating thickness and poor plating adhesion, and has poor rust resistance and welding workability. In No. 6, welding workability was poor because the second layer was thin and the wire feedability was not good. In No. 7, the plating thickness of the second layer was too large and the adhesion and workability were poor. In No. 8, the plating thickness at the final wire diameter was thin and the rust resistance was poor, and the workability was also poor. No. 9 was only electroplated and had good plating adhesion and rust resistance, but the workability was poor because the wire feedability was not stable. No.10 is the one that only chemical plating is applied,
The plating adhesion, rust resistance and workability were all poor.

[0018]

As described above, according to the present invention, it is possible to provide a flux-cored wire for arc welding which has good plating adhesion, rust resistance and welding workability.

[Brief description of drawings]

FIG. 1 is an explanatory view showing one embodiment of a manufacturing method of the present invention.

Claims (2)

[Claims] 1. A flux-cored wire for arc welding in which flux powder is placed in a shell formed by rolling a metal band, and a copper plating layer having a thickness of 0.1 μm or more formed by electroplating on the surface of the shell as a first layer. A composite copper plating layer comprising a copper plating layer having a film thickness of 0.1 to 5 μm by chemical plating as a second layer on the first layer, and the thickness of the composite copper plating layer is 0.2 μm or more. Characteristic flux-cored wire for arc welding. 2. A metal strip having a thickness of 0.2 μm or more copper plated by electroplating on one or both sides of the metal strip, and a second layer of chemical plating having a thickness of 0.2 μm on the first layer.
2 to 10 μm of copper plating is applied, the surface having the composite copper plating layer is used as an outer surface, the metal strip is bent into a U shape, and the flux is filled into the metal strip, and the thickness of the composite copper plating layer at the final wire diameter. Of the flux-cored wire for arc welding, characterized in that it is formed and drawn to have a size of 0.2 μm or more.