JP3219916B2 - Plating solid wire for arc welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to plating for arc welding with improved welding workability (including arc stability and feeding stability).
Regarding solid wire, it is applied to arc welding of various metal materials such as mild steel and high tensile steel.

[0002]

2. Description of the Related Art Arc instability is one of the major problems in welding workability in conventional arc welding. The causes include fluctuation of the energizing point and instability of the feeding property.

As a method of improving the arc instability, for a copper-plated solid wire, a wire for improving plating adhesion and plating film uniformity in order to stabilize a current-carrying point has been studied. Has been put to practical use. In addition, a technique such as a wire (JP-A-56-144892) oxidized at grain boundaries to stabilize the feeding property has been proposed.

[0004] However, the problem of arc instability for solid wires has not been improved to the extent satisfactory with plating adhesion, improved plating coverage, and grain boundary oxide wires alone. That is, the grain boundary oxide wire forms an oxygen-enriched layer on the surface of the wire, copper-plated the wire, and then draws the wire to form a lateral groove on the wire surface, and the liquid lubrication held in the lateral groove Although the agent improves the wire feeding property, the arc stability is insufficient. Attempts have also been made to improve the plating adhesion and the uniformity of the plating film, and to stabilize the current-carrying point between the chip and the wire. Not obtained.

An object of the present invention is to solve the above-mentioned drawbacks of the conventional wire and to provide a plated solid wire for arc welding which is excellent in arc stability without fluctuation of a current supply point and instability of feeding. .

[0006]

Means for Solving the Problems As means for solving the above-mentioned problems, the present invention relates to a plated solid wire for arc welding in which a plating film is formed on the surface of the wire, wherein the wire composition is expressed by weight% (hereinafter referred to as weight%). , The same), C: 0.
02-0.15%, Si: 0.5-1.0%, Mn:
1.0 to 2.0%, P: 0.04% or less, S: 0.03
% Or less, Cu: 0.10 to 0.40%, balance: iron and non-ferrous
A specific surface area value of the wire surface defined by the following equation (1) (hereinafter referred to as “wire specific surface area”).
It was suppressed to 0.01 or less, and (2) below arc welding plating solid wire, characterized in that to adjust the plating thickness index defined to 0.1 to 0.6 in expression. Wire specific surface area = (Sa / Sm) -1 (1) where, Sa: actual surface area of wire surface of measurement portion (mm ² ) Sm: apparent surface portion of measurement of actual surface area of wire surface Area (mm ² ) Plating thickness index = [Cu] x wire diameter ... (2) where [Cu]: Cu in the plated solid wire for arc welding
Amount (unit: wt%) Wire diameter: Wire diameter of plated solid wire for arc welding (unit: mm)

[0007]

The present invention will be described below in more detail. First, the results of a basic experiment that led to the knowledge of the present invention will be described.

[0008] The present inventors have proposed a solid wire,
When a wire was manufactured by changing the wire drawing method (lubricant, wire drawing speed, wire temperature, etc.), increasing or decreasing the amount of plated Cu, plating size, annealing conditions, etc., and investigating the arc stability,
Differences (good, bad) were found in the arc stability.

[0009] The cause was considered to be unstable feedability and fluctuation of the energizing point. First, the correlation between unstable feedability and arc stability was investigated. Specifically, the wire feedability was investigated without passing the welding current, but no good correlation with the arc stability investigation result was obtained.

Next, the arc stability is considered to be related to the electrical conductivity of the wire, and the roughness of the wire surface is determined by the SEM or the stylus method.
(JIS B0601, JIS B0651), and the relationship with workability was investigated.

Specifically, the relationship between arc stability and the results of measurement of surface roughness in the wire longitudinal direction by the stylus method and measurement results by a circularity meter in the circumferential direction were investigated.
No clear correlation was observed in the results from these two-dimensional measurement methods. However, through the SEM and the surface roughness measurement by the stylus method, two findings on which the present invention was based could be found.

First, the roughness of the wire surface obtained from observation by SEM does not always match the roughness obtained by the stylus method. Second, even though the roughness results obtained by the stylus method are the same, there is a difference in wire conduction and arc stability. For the above reasons, the stylus method was examined.In the roughness measurement by the stylus method, it was difficult to measure irregularities smaller than the curvature of the needle tip (fine concave parts cannot be measured, convex parts are broken by the stylus. Concluded) that no good agreement was found between the surface condition observed by SEM and the result measured by the stylus method.

Therefore, a measurement method for performing three-dimensional quantification of finer roughness and roughness is used. As a result of this measurement, a strong correlation between roughness and arc stability could be recognized. It was found that fine irregularities and three-dimensional irregularities (wire specific surface area), which cannot be measured by the conventional stylus method, greatly affected arc stability. The reason for this is not necessarily 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 (electric current point) between the tip and the wire becomes unstable, and as a result, the welding current becomes unstable It is estimated that the arc is not stable. It is considered that fine irregularities on the wire surface, which cannot be measured by the conventional surface roughness measuring method, greatly affect the arc stability.

Further investigation revealed that the arc stability greatly changed depending on the amount of copper plating applied to the wire surface.
By controlling the plating thickness index shown in (2) to a predetermined range, it has been found that the effect of suppressing the wire specific surface area becomes significant. This is presumably because the copper plating layer present in an appropriate amount suppresses irregularities on the wire surface caused by contact with dies, rollers, and the like in the wire drawing process after the copper plating process.

Plating thickness index = [Cu] × wire diameter (2) where [Cu]: Cu in the plated solid wire for arc welding
Amount (unit: wt%) Wire diameter: Wire diameter of plated solid wire for arc welding (unit: mm)

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

Incidentally, the apparent area of the measured portion is the area represented by length × width when the measured portion is developed on a plane. In the present invention, the actual surface area of a 500 μm × 600 μm (300,000 μm ² ) portion was measured after the measurement portion was developed on a plane.

The wire specific surface area is measured by a method under the following conditions.

Sampling method: Approximately 20 mm is sampled from any three places from the product wire wound on the spool so as not to scratch as much as possible, and organic materials such as petroleum ether, acetone, carbon tetrachloride, and chlorofluorocarbon which do not corrode the metal surface. Depending on the type of lubricant used in the solvent or processing process, it is attached to the wire surface by ultrasonic cleaning with a liquid (hot water or other degreasing liquid) that seems to be the most suitable to remove it Remove impurities such as dirt and oils. The ultrasonic cleaning is performed one by one so that the wires do not rub against each other to form a flaw. In the production of the wire, the flaws received from the dies by wire drawing, and flaws and abrasions caused by the contact between the facilities and wires, attention has been paid to avoid as much as possible, in that sense The specific surface area of the wire is measured by selecting a portion having no flaw.

Measurement position: One arbitrary cross section of the sample
The measurement is performed at three places shifted by 20 degrees, and a simple average of the measured values of a total of nine places of three samples is obtained.

Measurement magnification: 150 times (constant regardless of wire diameter). In addition, as a measuring device, ERA-8000 made by Elionix is mentioned, for example.

The present invention provides excellent arc stability by suppressing the wire specific surface area measured in the above manner to 0.01 or less and adjusting the plating thickness index to 0.1 to 0.5. It has been found that a plated wire for arc welding can be obtained.

Wire specific surface area: 0.01 or less The wire specific surface area affects the arc stability. The smaller the wire specific surface area, the better the arc stability. When it is assumed that welding is performed in a severe feed system, the upper limit of the wire specific surface area is set to 0.01 in order to secure wire feedability and maintain arc stability. The average surface roughness (Ra) measured by the above-mentioned ERA-8000 is desirably 0.4 μm or less. It is also desirable that the variation in the specific surface area in the longitudinal direction of the wire be within ± 0.005.

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

Plating thickness index: 0.1 to 0.6 The plating thickness index has an effect on the arc stability. If the plating thickness index is less than 0.1, the current flowing on the wire surface is impeded from flowing uniformly and regularly, and the arc is not formed. There is a problem of becoming a rule,
If it exceeds 0.6, the die is in contact with the soft copper plating during wire drawing, so that the plating is lost, and this missing portion causes instability of the current-carrying point, resulting in an irregular arc. A more preferred range is 0.2 to 0.5.

The wire composition of the plated wire for arc welding of the present invention is not particularly limited, and various compositions are possible, but a steel wire containing the following components is recommended.

C: 0.02 to 0.15% C is an indispensable component for obtaining the strength of the weld metal, but if it is less than 0.02%, the strength is insufficient as a high tensile strength steel weld metal. If it exceeds 0.15%, the cracking sensitivity is significantly increased, which is not preferable.

Si: 0.5 to 1.0% Si is indispensable as a deoxidizing element and is effective in increasing the yield strength of the weld metal. However, if it is less than 0.5%, deoxidation is insufficient, and if it exceeds 1.0%, the toughness of the weld metal decreases, which is not preferable.

Mn: 1.0 to 2.0% Mn is added together with Si as a deoxidizing element,
%, The tensile strength of the weld metal cannot be maintained, and, if it exceeds 2.0%, the drawability at the time of production becomes extremely poor, which is not preferable.

P ≦ 0.04%, S ≦ 0.03% P needs to be suppressed to less than 0.04% from the viewpoint of preventing cracking. In addition, since S causes hot cracking, it is necessary to suppress S to less than 0.03%.

Cu: 0.10 to 0.40 % If the Cu content is less than 0.10%, it is difficult to completely coat the exposed underlayer (Fe base). F on the wire surface
When the ground is exposed, the contact resistance on the wire surface becomes non-uniform, which causes arc instability. On the other hand, when the Cu content is 0.40
% , The internal stress of the plated Cu film increases, so that the plated Cu peels off in the feed roller portion and the inside of the conduit liner during welding, exposing the Fe ground, and as a result, the arc becomes unstable. The amount of Cu is mainly the amount of plated Cu.

In addition to the above components, one or two of Ti and Al can be added in an appropriate amount, if necessary.

Ti: 0.01 to 0.5% Ti is added as a deoxidizing element, and has the effect of forming an oxide to refine the microstructure of the weld metal and improve toughness. However, if it is less than 0.01%, deoxidation is insufficient, and if it exceeds 0.5%, it becomes difficult to manufacture a wire, which is not preferable.

Al: 0.001 to 0.5% Al is added as a deoxidizing element and has the effect of increasing the droplet viscosity. However, if the content is less than 0.001%, the droplet viscosity is low and the droplet transfer becomes unstable.

The other components are substantially iron, but the effects of the present invention are not inhibited even if the following elements are contained as impurities.

Ca is up to 50 ppm, Ni, Cr, Mo, Nb,
W can each be allowed up to 0.15%. As trace impurities, B ≦ 0.05%, V ≦ 0.05%, Zr ≦ 0.05.
05%, O (oxygen) ≦ 0.03%, N ≦ 0.02% are acceptable.

Next, examples of the present invention will be described.

[0038]

【Example】

Using various raw wires, the raw wire → intermediate drawing → annealing → pickling → finish drawing → depending on the production conditions of the product, the wire diameter is 1.0 to 2.0 mmφ with the chemical components shown in Table 1. A solid wire was prototyped. Welding was performed on a mild steel base material using these wires, and welding was partially performed with the feed system conditions changed to two levels to evaluate welding workability. Table 2 shows the welding conditions.

On the other hand, the specific surface area of each wire was measured by the above-mentioned measuring method. The results are summarized in Table 1.

In Table 1, wires Nos. 1 to 8 are examples of the present invention, and all exhibited good workability and mechanical performance.

On the other hand, the wire stability of the wire No. 9 of the comparative example is inferior because the plating thickness index is smaller than the lower limit of the range of the present invention. Since wire No. 10 also has a plating thickness index smaller than the lower limit of the range of the present invention, arc stability and feedability are poor. In addition, since the plating thickness index of the wires No. 11 and No. 12 is larger than the upper limit of the range of the present invention, the arc stability is inferior.

Since the wire No. 13 of the comparative example has a wire specific surface area value outside the range of the present invention, the arc stability is inferior. Since the wire No. 10 also has a wire specific surface area value outside the range of the present invention, arc stability and feedability are inferior. Since the wires No. 15 and No. 16 both have a wire specific surface area value and a plating thickness index outside the range of the present invention, arc stability and feedability are inferior.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

As described in detail above, according to the present invention,
We can provide plated solid wires for arc welding with excellent arc stability without fluctuations in the current-carrying point and instability of feeding, and can be applied to arc welding of various metal materials such as mild steel and high tensile steel it can.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-231590 (JP, A) JP-A-63-242487 (JP, A) JP-A-7-32186 (JP, A) JP-A-7-32 32187 (JP, A) JP-A-1-202391 (JP, A) JP-A-3-5096 (JP, A) JP-A-57-56170 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) B23K 35/02 B23K 35/30

Claims (2)

(57) [Claims] An arc welding plated solid wire having a plating film on the surface of a wire, wherein the wire assembly
C: 0.02 to 0.1% by weight (hereinafter the same)
5%, Si: 0.5 to 1.0%, Mn: 1.0 to 2.0
%, P: 0.04% or less, S: 0.03% or less, Cu:
0.10 to 0.40%, balance: iron and unavoidable impurities
Thus, the specific surface area of the wire surface defined by the following equation (1) (hereinafter, referred to as “wire specific surface area”) is suppressed to 0.01 or less, and the plating thickness index defined by the following equation (2) The plated solid wire for arc welding characterized by adjusting to 0.1 to 0.6. Wire specific surface area = (Sa / Sm) -1 (1) where, Sa: actual surface area of wire surface of measurement portion (mm ² ) Sm: apparent surface portion of measurement of actual surface area of wire surface Area (mm ² ) Plating thickness index = [Cu] x wire diameter ... (2) where [Cu]: Cu in the plated solid wire for arc welding
Amount (unit: wt%) Wire diameter: Wire diameter of plated solid wire for arc welding (unit: mm) 2. The composition of the wire further comprises: Al: 0.0
2. The plated solid wire for arc welding according to claim 1 , wherein the plated solid wire contains one or two of 0.01 to 0.5% and 0.01 to 0.5% of Ti.