JPH0732187A - Wire for arc welding - Google Patents

Abstract

PURPOSE:To provide the solid wire and flux cored wire which are free from a fluctuation in an energization point and instability of feedability and have excellent arc stability. CONSTITUTION:This wire for arc welding is the solid wire and flux cored wire for arc welding which suppress the specific surface area value of the wire surface defined by the following equation (specific surface area of the wire) to <=0.05. The specific surface area of the wire = (Sa/Sm)-1, where Sm is the apparent area (mm<2>) in the measured part where the actual surface area of the wire surface is measured; Sa is the actual area (mm<2>) of the wire surface of the measured part. The apparent area of the measured part refers to an area expressed by (vertical x horizontal) when the measured part is developed to a plane. The specific surface area value of the wire is preferably <=0.01 in a severe feed state. This wire is adequate for welding of mild steels, high tensile steels, low-alloy steels, stainless steels, etc., exclusive of aluminum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire for arc welding, more specifically, a solid wire and a flux-cored wire having excellent welding workability, such as mild steel except for aluminum, high strength steel, low alloy steel and stainless steel. The present invention relates to a welding wire suitable for welding, etc., and particularly having good arc stability.

[0002]

2. Description of the Related Art Arc instability is a problem of workability of conventional wire welding. The causes include fluctuations in the energizing point and instability in feeding performance.

As a method for improving this arc instability,
Regarding copper-plated solid wires, wires and the like have been implemented to improve the adhesion of plating and the uniformity of plating film in order to stabilize the conduction point. Further, in order to stabilize the feeding property, a grain boundary oxide wire (Japanese Patent Laid-Open No. 56-1448).
92) and other technologies were developed.

On the other hand, regarding the flux-cored wire,
As a method of improving arc instability, studies have been conducted such as plating a flux-cored wire to stabilize the energization point, and an arc stabilizer in the flux. Further, in order to stabilize the feeding property, the surface lubricant has been improved, the surface roughness has been examined, and the technical development of the coating method has been made (JP-A-57-32894).

[0005]

However, the problem of arc instability in solid wires has not been satisfactorily improved only by improving grain boundary oxidation wires, plating adhesion and throwing power.

[0006] That is, the grain boundary oxidized wire is formed by forming an oxygen-enriched layer on the surface layer of the wire, plating it with copper, and drawing the wire to form a lateral groove on the wire surface and holding it in the lateral groove. Although the liquid lubricant is used to improve the wire feedability, the arc stability is insufficient. Attempts have also been made to improve the plating adhesion and the uniformity of the plating film and stabilize the conduction point between the chip and wire.However, even if these factors are improved, satisfactory arc stability performance cannot be obtained. Not obtained.

Regarding the flux-cored wire,
The arc stability cannot be improved only by the examination as in the prior art.

Under the circumstances, the present invention solves the drawbacks of the conventional wire, does not cause the fluctuation of the energization point and the instability of the feedability, and is a solid wire and flux excellent in arc stability. The purpose is to provide a cored wire.

[0009]

In order to solve the above-mentioned problems, the inventors of the present invention, regarding the solid wire, the drawing method (lubricant, drawing speed, wire temperature, etc.), increase / decrease in the amount of plating Cu, Prototypes of wires with different plating sizes and annealing conditions were produced. Also, for cored wires, various types of wires were produced by changing the conventional production conditions and flux composition.
When the arc stability was investigated, there was a difference in arc stability.
(Good and bad) was recognized.

Since the cause of this may be unstable feeding and fluctuation of the energizing point, first, the correlation between unstable feeding and arc stability was investigated. Specifically, the wire feedability was investigated without passing current, but no good correlation with the arc stability investigation results was obtained.

Next, it is considered that the arc stability is related to the electrical conductivity of the wire, and the roughness of the wire surface is measured by SEM or the stylus method (JIS B0601, JIS B0651), and the relationship with the workability is determined. saw. From the result of measuring the roughness of the surface in the longitudinal direction of the wire by the stylus method, and from the measurement result of the circularity meter in the circumferential direction, the relationship with the arc stability was investigated,
No clear correlation was observed in the results from these two-dimensional measurement methods.

However, through the surface roughness measurement by the SEM and the stylus method, the two findings forming the basis of the present invention could be found.

First, the roughness by the stylus method and the wire surface condition obtained by SEM observation do not always match. Secondly, even if the results of roughness by the stylus method are the same, there are differences in the wire conductivity and arc stability. For the above reasons, as a result of examining the stylus method, it is difficult to measure unevenness smaller than the curvature of the needle tip by the roughness measuring method by the stylus method (fine concave portions cannot be measured, convex portions are touchable). It was concluded that there is no good agreement between the surface condition observed by SEM and the result measured by the stylus method.

Therefore, a measuring method for finer roughness and three-dimensional quantification of roughness was used. As a result of this measurement, a strong correlation between roughness and arc stability could be recognized. It was found that the fine roughness and three-dimensional roughness (wire specific surface area), which cannot be measured by the conventional stylus method, have a great influence on the arc stability. The reason for this is not always clear, but if the wire specific surface area on the wire surface is large, that is, if the irregularities on the wire surface become large, the contact point (current-carrying point) between the chip and the wire becomes unstable, and as a result, the current becomes unstable. Therefore, it is estimated that the arc is not stable.
It is considered that the microscopic asperities on the wire surface, which cannot be measured by the conventional surface roughness measuring method, have a great influence on the arc stability.

This effect is the same for solid wires plated with copper and for solid wires without plating. Furthermore, a similar tendency was obtained even when the solid wire was replaced with the flux-cored wire.

Here, the wire specific surface area is the apparent area of the measurement portion where the actual surface area of the wire surface is measured, Sm.
(mm ² ), where Sa (mm ² ) is the actual surface area of the wire surface of the measurement portion, it is defined by the following formula (see FIG. 1). Wire specific surface area = (Sa / Sm) -1

The apparent area of the measurement portion is an area expressed by length × width when the measurement portion is developed on a plane. In the present invention, after the measurement portion is developed on a plane, 500
The actual surface area of a portion of μm × 600 μm (300000 μm ² ) was measured.

The specific surface area of the wire is measured by the method under the following conditions.・ Sampling method: Petroleum ether that does not corrode the metal surface by collecting about 20 mm from any 3 points so as not to scratch the product wire wound on the spool as much as possible.
Depending on the type of lubricant used in the organic solvent such as acetone, carbon tetrachloride, chlorofluorocarbon, etc., or in the processing process, the liquid that seems to be most suitable for removing it (hot water or other degreasing liquid)
By performing ultrasonic cleaning with, impurities such as dirt and oil and fat adhering to the wire surface are removed. Ultrasonic cleaning is performed one by one so that the wires do not rub against each other and scratch. In the production of wire, the flaws received from the die by wire drawing, among the various parts of the equipment and the contact between the wires, it is noted that scratches and scratches are not generated as much as possible, and its meaning. Then, the specific surface area value is measured by selecting a part having no flaw.・ Measurement position: One arbitrary cross section of one sample is measured at three locations shifted by 120 degrees, and a simple average of the measured values of nine locations of the three samples is taken. -Measurement magnification: 150 times (constant regardless of wire diameter). As the measuring device, for example, ERA-800 manufactured by Elionix Co., Ltd.
0 is mentioned.

The present invention has found that by suppressing the wire specific surface area measured as described above to be 0.05 or less, a solid wire for arc welding and a flux-cored wire excellent in arc stability can be obtained. It is a thing.

Next, the reason for limiting the numerical values will be described.

Wire specific surface area of 0.05 or less: The wire specific surface area affects the arc stability, and the smaller the wire specific surface area, the more the arc stability increases. However, in practice, wires up to 0.05 or less can be sufficiently used, and the upper limit of the wire specific surface area is set to 0.05.

In a severe feeding condition, a further low wire specific surface area value is required to secure the arc stability. Therefore, the upper limit of the wire specific surface area is preferably 0.01. Average surface roughness (Ra) measured by the above-mentioned ERA-8000
Is preferably 0.4 μm or less. Further, it is desirable that the variation of the specific surface area value in the longitudinal direction of the wire is also within ± 0.005.

As a method of reducing the specific surface area of the wire, wet drawing is smaller than dry drawing, the drawing speed is reduced, and the area reduction rate is subdivided by changing the drawing die schedule. By reducing the plating diameter,
It is possible to reduce the wire specific surface area.

The present invention can obtain the same effect regardless of the composition of the wire.

Next, examples of the present invention will be described.

[0026]

Example 1 This example is an example of a mild steel solid wire.

Solid wires having the chemical composition shown in Table 1 and a wire diameter of 1.2 mmφ were produced by the production method shown in Table 2 using various kinds of raw wires. According to the welding conditions shown in Table 3, some of them were welded on the mild steel base material while changing the feeding conditions to two levels, and the welding workability was evaluated. On the other hand, the wire specific surface area and Ra of each wire were measured by the above-described measuring method. The results are summarized in Table 4.

Wires No. 1 to No. 5 are examples of the present invention,
All showed good workability. Under severe feed conditions, the wire having a lower specific surface area and Ra showed better results. On the other hand, the wire No. of the comparative example.
6, No. 7, and the conventional wires A to C have a wire specific surface area of more than 0.05, and all have poor welding workability. 2 and 3 are SEM images and three-dimensional bird's-eye views of the wire surface for the wires No. 1 (inventive example) and No. 7 (comparative example). 2 shows the case of wire No. 1 and FIG. 3 shows the case of wire No. 7.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

[Table 4]

[0033]

Example 2 This example is an example of a stainless solid wire.

A stainless solid wire was trial-produced in the same manner as the case of the mild steel solid wire. The chemical composition of the wire, the manufacturing process, and the welding conditions are shown in Table 5, Table 6, and Table 7,
Table 8 shows the wire specific surface areas of the conventional wire and the trial wire.

As is clear from Table 8, all three trial wires of the present invention exhibited good workability under normal feeding conditions.

[0036]

[Table 5]

[0037]

[Table 6]

[0038]

[Table 7]

[0039]

[Table 8]

[0040]

Example 3 This example is an example of a seamless flux-cored wire.

Using the flux having the composition shown in Table 9 and the outer shell shown in Table 10, a seamless flux-cored wire having the specifications shown in Table 11 was manufactured by the manufacturing process shown in Table 12. These were welded on a mild steel base material under the welding conditions shown in Table 13, and the welding workability was evaluated. The wire specific surface area and Ra were measured for each wire by the above-described measuring method. The results are shown in Table 14.

As is clear from Table 14, all the trial wires of the examples of the present invention exhibited good workability under normal feeding conditions.

[0043]

[Table 9]

[0044]

[Table 10]

[0045]

[Table 11]

[0046]

[Table 12]

[0047]

[Table 13]

[0048]

[Table 14]

Since aluminum has a lower melting point than mild steel, high-strength steel, low-alloy steel, stainless steel, etc., it is necessary to increase the number of current-carrying points in the chip, and the wire specific surface area is 0. Wires for aluminum are excluded because it is insufficient at 0.05 or less.

[0050]

As described in detail above, according to the present invention,
It is possible to provide a solid wire and a flux-cored wire that have excellent arc stability without fluctuations in energization points and instability in feedability. Mild steel except for aluminum, high strength steel,
Suitable for welding low alloy steel, stainless steel, etc.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of measurement of a wire specific surface area.

2 is a wire surface of the solid wire No. 1 of Example 1. FIG.
In the photograph showing (metal structure), (a) shows the uneven state,
(B) is an SEM image.

3 is a wire surface of the solid wire No. 7 of Example 1. FIG.
In the photograph showing (metal structure), (a) shows the uneven state,
(B) is an SEM image.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yo Wada 100-1 Urakawachi, Fujimae, Fujisawa-shi, Kanagawa Kobe Steel Fujisawa Plant (72) Inventor Seiichi Yokoshima 100, Urakawachi, Miyazawa, Fujisawa-shi, Kanagawa No. 1 Stock Company Kobe Steel Works Fujisawa Works

Claims (1)

[Claims] 1. A solid wire for arc welding and a flux-cored wire, wherein the specific surface area value of the wire surface defined by the following formula (hereinafter referred to as wire specific surface area) is suppressed to 0.05 or less. Wire specific surface area = (Sa / Sm) -1 where: Sm: apparent area of the measurement portion where the actual surface area of the wire surface was measured (mm ² ) Sa: actual surface area of the wire surface of the measurement portion (mm ² )