JPH0115356B2 - - Google Patents

Description

[Detailed description of the invention]

purpose of invention

[Industrial application field]

The present invention relates to improvements in gas-shielded arc welding wires, and also includes a method for manufacturing the same.

[Conventional technology]

Electrode wire for gas shielded arc welding (hereinafter referred to as
In the past, it was believed that the surface of wires (simply referred to as "wires") should be microscopically smooth and that the amount of residual lubricant used in the manufacturing process should be kept as low as possible. This is because it is important to ensure that the wire passes smoothly through the conduit tube of the welding equipment in order to prevent spatter, and also to prevent welding defects due to decomposition products of lubricants such as oil and fat during welding. This was done to prevent the conduit tube from accumulating in the conduit tube and interfering with stable wire feeding due to dust attached with the lubricant. However, even though extremely reducing the amount of lubricant is effective in reducing welding defects caused by the lubricant components mentioned above, it still inevitably leads to uneven feeding due to lack of lubricant, making it difficult to feed the wire. Increases the occurrence of spatter due to micro vibrations. So, the wire
It has been proposed to solve this problem by using a regulated amount of lubricant in the range of 0.5 to 2 g per 10 kg. However, in practice, if an amount of lubricant close to the lower limit within the above range is used on the microscopically dense and smooth wire surface, it is extremely difficult to create a uniform lubricant coating on the wire surface. There is also a risk that the lubricant film may be wiped off by contact with other objects, and the wire charcoal feeding often lacks stability, making the purpose of preventing spatter impossible. On the other hand, considering the welding defects caused by the decomposition products of the lubricant, it is better to use less lubricant. Furthermore, if too much lubricant is used, the wire feeding resistance tends to increase as the device is used for a long time. It turns out that this is because too much lubricant makes it easier for wires to become dusty, and that dust accumulates inside the conduit tube.

[Problems to be solved by the invention]

The purpose of the present invention is to provide a welding wire that solves the above-mentioned problems, improves feedability during welding, provides stable work, reduces the occurrence of spatter, and enables welding with a low risk of welding defects. and to provide a suitable manufacturing method thereof. Composition of the invention

[Means to solve the problem]

The gas shielded arc welding wire of the present invention is
The surface of the welding wire material is coated with a porous copper plating layer having a porosity of 5 to 50%, and this plating layer is impregnated with a lubricant. Here, "porosity" is defined as the ratio (%) of the area of the entire surface occupied by a portion that is more concave than the apparent surface when the wire surface is observed under a microscope. The lubricant used can be any conventionally used lubricant, and its amount can be smaller than conventionally as long as a surface coating layer with appropriate porosity is provided, for example, 0.1 to 0.5 g per 10 kg of wire, compared to the conventional 0.5 to 2 g. A low wire feed resistance comparable to that obtained is obtained. One embodiment of the method for producing the welding wire of the present invention is to apply copper plating to the surface of the welding wire material under conditions that provide a porous plating layer, and apply a lubricant to this plating layer to reduce the area reduction. Wire drawing is carried out under conditions of 60 to 10% to obtain a desired wire diameter, and the porosity of the plating layer is adjusted to a range of 5 to 50%. Another method is to apply copper plating under conditions that provide a porous plating layer to the surface of the welding wire material, pickle the plating layer, and then apply a lubricant to achieve an area reduction rate of 80 to 10%. The process consists of drawing the wire under certain conditions to obtain the desired wire diameter and adjusting the porosity of the plating layer within the range of 5 to 50%. As the plating means, both electroplating and chemical immersion plating can be used, and vapor phase plating, that is, vapor deposition can also be used. Chemical plating tends to provide a porous plating layer, but even in electroplating, the porosity can be adjusted by selecting current density and other electrolytic conditions. The specific method may be based on what is known in the plating technology, with reference to the examples described later. Although it will be readily appreciated that the present invention is applicable to any welding wire used in gas-shielded arc welding, a typical field of application is where the wire material is mild steel or low alloy steel. It is something.

[Effect]

The present inventors have obtained the following knowledge as a result of research aimed at solving the above-mentioned problems. First, for stable wire feeding, it is more important whether the wire surface is uniformly coated with lubricant than whether it is microscopically smooth. Even if the wire surface is smooth and a microscopically sufficient amount of lubricant is applied, uneven adhesion, especially breaks in the lubricant coating, will deteriorate feeding performance. A uniform coating of lubricant can be obtained by making the wire surface moderately porous and allowing the lubricant to exist there, rather than by making the wire surface dense and smooth. Second, in the plating process that is often carried out in wire manufacturing, depending on the plating conditions, it is possible to provide a plating layer with the above-mentioned appropriate porosity. The porosity of this layer decreases, and the degree of porosity increases as the area reduction rate increases, and the porosity can be increased by pickling after plating. By utilizing these facts, the porosity of the plating layer on the wire surface can be controlled to a desired level. As is clear from the examples shown later, when the porosity of the plating layer is as low as 5%, the effect of providing a base for the lubricant is insufficient.On the other hand, when the porosity is higher than 50%, the surface The feeding resistance increases due to the roughness of the feed. As mentioned above, the porosity of the plating layer decreases due to expansion and contraction after plating, so in order to ensure the necessary porosity, the area reduction rate of wire drawing cannot be set too high. Normally it should be kept below 60%. On the other hand, if pickling is performed after plating, the porosity of the plating layer will increase as mentioned above, so if this step is added, the restrictions on the area reduction rate during wire drawing will be relaxed,
It can be set as high as 80% of the upper limit. In any of the above cases, the area reduction rate for wire drawing should be selected to be 10% or more. At a low area reduction rate of less than 10%, it is generally difficult to reduce the porosity of the porous plating layer formed on the wire surface to less than the above-mentioned upper limit of 50%.

[Example] C Si Mn P S Fe 0.03 0.79 1.56 0.009 0.014 Remainder A wire having the above composition (%) was used and processed according to the manufacturing process listed in Table 1. The conditions for plating and subsequent pickling are shown in Table 2. The properties of the obtained wire are shown in Table 3. Rapeseed oil was used as a lubricant and diluted in various proportions with pentane to control the amount of adhesion. No. 1 shown for comparison is an example where the area reduction rate is too low and the porosity exceeds the upper limit, and No. 8 is an example where the area reduction rate is too high and the porosity becomes extremely low. It is.

【table】

【table】

【table】

[Table] ** Degreased after final wire drawing Next, a welding test was conducted using these sample wires under the following welding conditions, and the wire feeding resistance within the conduit tube when 500 kg of wire was used. was measured. Welding machine (capacity): Semi-automatic welding machine (500A) Conduit tube: Tube length 3m, inner diameter 3mm Welding current: 350A Arc voltage: 35V Welding speed: 28cm/min Shielding gas: CO ₂ 20/min Porosity and wire feeding The relationship with resistance is shown in Figure 1.
Furthermore, the relationship between porosity and slope ratio during wire drawing is shown in FIG. The graph in Figure 1 shows that the porosity of the wire surface layer is 5.
As long as it is within the range of ~50% (No. 2 to No. 7 and No.
9) Regardless of the amount of lubricant, the feeding resistance will always be low (2.3-3.7Kg), and even if the porosity is higher (No. 2) or lower (No. 2) than this range.
8) indicates that the feed resistance will be high (5Kg or more). Speaking of lubricants,
Conventionally, it was thought that 0.5 g or more of lubricant was required per 10 kg of wire to ensure good wire feedability, but according to the present invention, it has been found that a smaller amount is sufficient. The graph in FIG. 2 also shows that the porosity of the wire surface decreases as the area reduction increases. In order to obtain a wire with a dense and smooth surface, which has been thought to have good feedability, a high area reduction rate (No. 8) of 80 to 90% or more is required, but the present invention In order to obtain a wire of
This can be seen from Figure 2. It can also be seen that if a pickling process is added after plating, an area reduction rate as high as 80% can be used. (No. 7) Even if the wires come into contact with other objects, it is desirable that the attached lubricant is not wiped off, so to check this, wipe the surface of each wire with dry gauze. , the amount of remaining lubricant was measured. The results are shown in Table 4. The data in Table 4 shows that in the wire (No. 8) with very low surface porosity, the lubricating oil is easily wiped off by contact with other objects.

[Table] Separately, the surface of the wire of the present invention was photographed using a scanning electron microscope and compared with a conventional wire having a dense and smooth surface. Figures 3A to 3C and Figure 4 are photographs of the same, and it can be seen that the former have pores distributed and can serve as bases for lubricant, but no such pores are found in the latter. do not have. Effects of the Invention The wire for gas-shielded arc welding of the present invention has excellent feedability because it has only a small amount of lubricant on the surface to the extent that it has no adverse effect on welding. As a result, welding work when manufacturing boilers or other pressure vessels, various chemical reaction vessels, etc. can be carried out stably and with less spatter, and a good welded part without defects can be obtained. Such a wire can be obtained by drawing a porous plating layer at a specific reduction in area according to the present invention.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the porosity of the surface of the welding wire and the feeding resistance in the conduit tube of the welding device when 500 kg of the welding wire is used. Figure 2 shows the porosity (%) of the wire surface relative to the area reduction rate (%) of wire drawing performed during wire manufacturing.
This is a graph showing. Figure 3 A, B and C are
Both are electron micrographs (magnification: 1000) of the surface of the wire according to the present invention, and FIG. 4 is a similar electron micrograph (magnification: 1000) of the surface of a conventional wire.

Claims (1)

[Scope of Claims] 1. A gas-shielded arc welding wire comprising a welding wire material whose surface is coated with a porous copper plating layer having a porosity of 5 to 50%, and this plating layer contains a lubricant. 2 Copper plating is applied to the surface of the welding wire material under conditions that provide a porous plating layer, a lubricant is applied to this plating layer, and wire drawing is performed under conditions of an area reduction rate of 60 to 10% to form the desired wire. A method for manufacturing a wire for gas shielded arc welding, which comprises adjusting the diameter and the porosity of the plating layer to a range of 5 to 50%. 3 Copper plating is applied to the surface of the welding wire material under conditions that provide a porous plating layer, and after this plating layer is pickled, a lubricant is applied to increase the area reduction rate to 80~
A method for manufacturing a wire for gas shielded arc welding, which comprises drawing the wire under conditions of 10% to obtain a desired wire diameter and adjusting the porosity of the plating layer to a range of 5 to 50%.