JPH08243779A - Steel wire for gas shielded arc welding - Google Patents

Abstract

PURPOSE: To improve arc stability and to lessen the generation of spatters by adhering a specific amt. of one or >=2 kinds of potassium sulfate, sodium nitrate and potassium chlorate added into lubricating oil onto the surface of a steel wire. CONSTITUTION: The lubricating oil with which one or >=2 kinds of the potassium sulfate, sodium nitrate and potassium chlorate are mixed is adhered onto the surface of the steel wire for gas shielded arc welding subjected to copper plating, etc. The adhesion thereof is specified to 0.1 to 10.0g per 10kg wire. The potassium sulfate, sodium nitrate and potassium chlorate are decomposed by releasing oxygen at about 40 deg.C. The presence of this oxygen lowers the viscosity of molten steel. Consequently, the desorption of the globule from the front end of a wire is facilitated and a contribution is made to an improvement in the arc stability. The adhesion to the wire is executed by adding one or >=2 kinds of the potassium sulfate, sodium nitrate and potassium chlorate to the lubricating oil which consists of vegetable oils and mineral oils and is used at the time of finish drawing.

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 steel wire used for full-automatic and semi-automatic welding of steel.

[0002]

2. Description of the Related Art In recent years, welding robots, automatic welding machines, etc. have been introduced to promote high-speed automation of welding. Along with this, high demands have been made due to the performance of welding wires and welding workability. ing. Generally, 0.8 to 2.4 mm for CO ₂ gas shield arc welding, MIG welding, etc.
Diameter copper plated welding steel wire is used. These welding wires are usually used for welding in a state of being wound on a spool or a bobbin or loaded in a pail pack. When these wires are used,
It is installed in a feeder, which is an accessory device of the welding machine, and welding is performed through a flexible conduit cable, a welding torch, and a contact tip extending 3 to 20 m through a feeding roller.

The gas shielded arc welding method has a tendency to expand its application range by taking advantage of its characteristics of high efficiency, high quality and low cost as compared with other welding methods. However, although the gas shielded arc welding method has the characteristics of high efficiency and high quality, there are problems such as frequent occurrence of spatter during welding. Therefore, many measures and studies have been made to reduce the amount of spatter generated in the gas shield arc welding method. Improvement of first welding power supply characteristics, conversion of CO ₂ shield gas to Ar, a method of increasing the oxygen concentration in the wire surface layer portion are known from improvement and CO ₂ welding power supply characteristic A
Although conversion to r can be expected to be effective, it is economically unfavorable because of high cost.

On the other hand, JP-A-60-40685, JP-A-60-162595 and the like disclose methods for increasing the oxygen concentration in the surface layer of the wire. Since it has the effect of lowering the droplets, if the surface oxygen concentration of the droplets suspended on the tip of the wire becomes high, the droplets will become particles even with a slight pinch force. It is considered that the fine droplets regularly move to the crater and the arc stability is improved.

As a method for increasing the oxygen concentration in the surface layer of the wire, the wire is annealed in an oxidizing atmosphere to form an oxide film on the surface, and then an appropriate amount of oxide film is formed by controlling the pickling conditions. There is a method to make it remain. This method requires complicated heat treatment and pickling control at the manufacturing stage, such as annealing at 700 ° C. for 4 hours or more when increasing the surface oxygen concentration. Further, during welding, the plating peels off and clogs the chips, which hinders the wire feedability, which causes problems such as unstable arc and frequent spattering. Further, Japanese Patent Publication No. 64-6833 discloses a method of enriching necessary oxygen by, for example, oxidizing copper in an oxidizing atmosphere after plating. There is a problem that the electrical conductivity between the chips becomes unstable and spatter frequently occurs.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the conventional wire as described above, improve the arc stability and reduce the spatter. An improved fully automatic and semi-automatic welding steel wire is provided.

[0007]

Means for Solving the Problems The present invention is to solve the above problems, and in a steel wire for gas shielded arc welding, one or more of potassium nitrate, sodium nitrate and potassium chlorate in a lubricating oil is used. The steel wire for gas shield arc welding, characterized in that 1.0 to 10.0 g per 10 kg of the wire is adhered to the surface of the steel wire.

[0008]

The present invention will be described in detail below. Although many methods for improving welding workability by increasing the oxygen concentration in the surface layer of the wire have been disclosed as described above, there is a problem that the annealing time, temperature, etc. increase the cost compared with the prior art. The present invention has been made in view of those points.
Oxygen is an element that lowers the surface tension, and its action is believed to improve droplet transferability.
The present inventors have noted that oxygen also exerts an action of lowering the viscosity of molten steel. That is, it was presumed that the presence of oxygen reduced the viscosity of the molten steel, which facilitated the detachment of droplets from the tip of the wire and contributed to the improvement of arc stability.

As a method for increasing the oxygen concentration in the wire surface layer without using the annealing time or temperature control method, US Pat. No. 2,818,496 discloses a method in which iron oxide is applied by mechanically providing a wire surface with irregularities, or a special method. Kaihei 5
Japanese Patent No. 69181 discloses a method in which a lubricating oil mixed with iron oxide powder is used for wire drawing and the iron oxide powder is incorporated into the recesses of the plating layer. All of these have in common that iron oxide is used as the oxygen source, but when iron oxide is used, an arc is generated between the tip and the wire during welding and arc becomes unstable, and further iron oxide powder is contained in the tip. This is an unfavorable method because it obstructs clogging welding.

The present inventors have obtained the following knowledge as a result of repeated basic research aiming at solving the above-mentioned various problems. 40 for potassium nitrate, sodium nitrate and potassium chlorate
Attention was paid to the fact that it has the characteristic of releasing oxygen and decomposing at around 0 ° C. 2KClO ₃ → 2KCl + 3O ₂

Since potassium nitrate, sodium nitrate, and potassium chlorate are not metal powders, arc is not generated between the tip and the wire during welding, so that welding is not hindered. As a method for adhering to the wire, it is possible to mix it with a lubricating oil such as vegetable oil or mineral oil used for finish drawing. Both have a density of 2.1 to 2.3 g / m.
^Since it is ³ , it is easy to mix it uniformly with the lubricating oil. Since it does not precipitate in the lubricating oil like iron oxide powder having a high density, it can be uniformly and surely attached to the wire.

Next, the reasons for limiting each component will be described.
The amount of potassium nitrate, sodium nitrate, and potassium chlorate attached to the wire is 1.0 to 10.0 per 10 kg of wire.
The reason for limiting to g is as follows. That is, 1.
If it is less than 0 g, the effect of improving the welding workability is not recognized, and 1
If the amount exceeds 0.0 g, the amount of oxygen released during welding will be too large and it will be effective in reducing spatter, but the conductivity of the wire surface will decrease, the electrical conductivity between the tip and the wire will deteriorate, and the arc will become unstable. 1.0-10.0g per 10kg
Limited.

[0013]

EXAMPLES Next, the present invention will be described more specifically by way of examples. Steel wire for gas shield arc welding with 0.4 μm copper plating (JIS Z3312 YGW1
1, C: 0.10%, Si: 0.81%, Mn1.61
%, P: 0.010%, S: 0.016%, Ti: 0.
22%, wire diameter: 2.4 mm) in the final wire drawing step (2.
(4 → 1.2 mm), a test was conducted in which the combination of potassium nitrate, sodium nitrate and potassium chlorate was changed and added to the lubricating oil. The tests were conducted with various amounts of adhesion. In Table 1, for comparison with the wire of the present invention, the electric conductivity, the amount of spatter, and the bead appearance when welding was performed using a wire outside the range of the present invention, and the obtained values are also shown.

[0014]

[Table 1]

The electrical conductivity was investigated by the electrical conductivity between the chip and the wire. When the quality was judged to be worse, an arc was generated between the tip and the wire, the wire feeding became unstable, and the welding was interrupted. Conduit liner is 6m (inner diameter: 1.4
mm) made of stainless steel), with a diameter of 3
A loop of 00 mm was applied.

The amount of spatter was measured by measuring the amount of spatter captured in the copper collection box. Welding was performed with a CO ₂ gas shield, welding conditions were downward bead-on-plate welding at 320 A-32 V-30 cm / min, and the distance between the tip and the base metal was constant at 20 mm. Regarding the amount of spatter, the commercially available wire is usually around 2.0 g / min under these welding conditions, but since the main object of the present invention is to reduce the amount of sputter, 1.5 g / min or less was passed. The electrical conductivity was judged to be unacceptable if the arc was interrupted once. The quality of the bead appearance was evaluated by the alignment of the bead toes and the bead waveform.

As shown in Table 1, the wires 1 to 10 of the present invention
The sputtering amount was 1.5 g / min or less, and the electric conductivity was such that the arc was not interrupted during welding, good welding workability was exhibited, and the bead appearance was also good.

The comparative wires 11 to 14 are 10 kg of wire.
Since the amount of deposit per contact is too large at 12.5 to 40.5 g, the surface oxygen concentration of the droplets suspended on the tip of the wire is too high, the droplets grow large, spatter frequently occurs, and the arc becomes unstable. It was On the other hand, in the case of the conventional wire 15 which does not use the adhered component, the target spatter generation amount is 1.5 g / min.
It did not go below.

[0019]

The present invention is constituted as described above and comprises one or two of potassium nitrate, sodium nitrate and potassium chlorate.
Mix 10 or more seeds in lubricating oil, and wire 10
By applying 1.0 to 10.0 g per kg,
It has a high industrial value because it improves welding workability and responds to welding automation, robotization, and high efficiency.

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Claims (1)

[Claims] 1. A steel wire for gas shielded arc welding, wherein one or more kinds of potassium nitrate, sodium nitrate and potassium chlorate are mixed in a lubricating oil, and 1.0-10. Steel wire for gas shielded arc welding, characterized in that 0 g is adhered.