JP3017058B2 - Cut wire for welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cut wire for welding suitable for use as an arc start material for various weldings and a filling material in a groove, and more particularly to an arc start property, hot cracking resistance and hydrogen cracking resistance. Excellent cutting wire for welding.

[0002]

2. Description of the Related Art Conventionally, when starting welding such as submerged arc welding and electroslag welding using a large diameter wire, as an arc start material for easily generating an arc between a welding wire and a steel plate to be welded, Cut wires coated with steel wool and C (carbon) are commonly used. In addition, in submerged arc welding and the like, for the purpose of increasing the welding amount and controlling the penetration depth, a method in which iron powder or a general cut wire is scattered and filled in a welding groove, and thereafter, welding is widely performed. Has been adopted.

[0003]

However, the above-described starting materials, such as steel wool and cut wires coated with C, as well as iron powder and general cut wires, which are fillers in the groove, have the following problems. However, it cannot be used as both an arc start material and a filling material in a groove, which is a major obstacle to achieving full automation.

[0004] Although the steel wool used as a starting material has an extremely good arc-starting property, it requires time and effort because the steel wool needs to be manually rounded to an appropriate size and disposed in the arc-start portion. There are difficulties. When steel wool is used as the filling material in the groove, it is extremely difficult to fill the groove due to its characteristics. Further, since the bulk density is extremely small, the effect of the high welding speed is hardly produced as the filler in the groove.

[0005] The cut wire coated with C used as a starting material has the second best arc-starting property after steel wool, and it is also easy to fill the cut wire into a groove or the like (Japanese Patent Laid-Open Publication No. HEI 9-26139). 6-29715
No. 0). However, when the cut wire is repeatedly subjected to collision and friction during transportation and in the automatic spraying machine, the coating of C easily peels due to friction and collision between particles, and C is applied to the wire. In comparison, since the specific gravity is about 1/10, C segregation occurs during welding. Segregation of C in the weld metal is undesirable because it causes hot cracking and hydrogen cracking. Therefore, when sprayed on the tab, the degree of adverse effect is small, but when sprayed within the groove of the main welding, there is a possibility that welding failure may be caused. In particular, in recent years, in which the base material has been increasing in tension, the tendency of hydrogen cracking to become a problem increases.

[0006] Iron powder, which is a filling material in a groove, is advantageous in that it is inexpensive and easy to control the spraying height because of its fineness. However, when iron powder is used as the arc start material, there is a disadvantage that the arc start property is inferior to the above-described cut wire coated with C. In addition, when welding is performed outside, there is a problem that it is easily scattered by wind. Further, since the bulk specific gravity is relatively small, it is difficult to obtain a high welding speed. In addition, when a large amount of an alloy component is added to iron powder, component segregation easily occurs, and welding defects such as high-temperature cracking and hydrogen cracking easily occur.

[0007] When a general cut wire is used as a filling material in a groove, it has an advantage that a high welding speed can be easily obtained, and that automatic spraying and adjustment of components in a weld metal are easy. is there. However, since the arc start performance is inferior, there is a problem that almost no ignition occurs particularly when welding is performed at a low current density using a large-diameter welding wire. In addition, the use of a material with poor rust resistance and stored for a long time increases the amount of diffusible hydrogen in the weld metal,
Particularly in the case of high-strength steel, the risk of hydrogen cracking increases.

The present invention has been made in view of the above problems, and has excellent arc starting properties, can be used as a filling material in a groove, and has good hot cracking resistance and hydrogen cracking resistance. An object of the present invention is to provide a simple welding cut wire.

[0009]

The welding cut wire according to the present invention is a welding cut wire in which a Cu coating layer is formed so as to cover the cut wire strand and oil is further applied. The diameter D of the cut wire is 0.6 to 2.0 mm, the length L in the longitudinal direction is 0.5 to 2 Dmm,
The value obtained by dividing the amount of Cu deposited on the Cu-deposited layer by the total weight of the cut wire is 0.03% or more in percent, and the value obtained by dividing the oil content of the oil by the total weight of the cut wire is p.
It is 5 to 200 ppm in pm.

It is preferable that a value obtained by dividing the Cu deposition amount by the total weight of the cut wire is 0.25% or less in percent.

[0011] The Cu deposition layer may be formed on the entire surface of the cut wire, or may be formed on a peripheral surface of the cut wire.

The oil may be applied to the entire surface of the cut wire, or may be applied to the peripheral surface of the cut wire.

[0013]

The present inventors have conducted intensive studies in order to impart a good arc start property to a cut wire.
It has been found that by forming a Cu coating layer having an appropriate weight on the surface of the cut wire strand, the arc start property is improved. In addition, it was clarified that by applying an appropriate amount of oil to the surface of the cut wire, rust resistance was improved without impairing arc start performance, and hydrogen cracking resistance and porosity were improved. Furthermore, as a result of examining the shape of the cut wire, the present inventors have found a cut wire in which scattering due to wind or the like is suppressed as much as possible while maintaining the arc start property, and the present invention has been accomplished.

Hereinafter, the reason for the numerical limitation in the present invention will be described.

Cut wire diameter D: 0.6 to 2.0
It is necessary to set the diameter D of the mm cut wire so that the cut wire becomes too light and does not scatter, and an optimal current density for arc start can be obtained. When D is less than 0.6 mm, small diameter processing is required to obtain this diameter, and the economic efficiency is poor. In addition, there is a problem that the cut wire is easily scattered by wind and the like, and the bulk density is easily reduced. Furthermore, since the ratio of the surface area to the total weight of the cut wire becomes too large,
The ratio between the total weight of the cut wire and the amount of Cu attached to the cut wire, and the ratio between the total weight of the cut wire and the oil content of the cut wire easily exceed appropriate ranges.

On the other hand, when D exceeds 2.0 mm, the current density becomes too large, so that the arc start performance is deteriorated and the filling of the groove inner bottom is deteriorated. Therefore, the diameter D of the cut wire is set to 0.6 to 2.0 mm.

The wire length L of the cut wire: 0.5 to 2 Dm
The wire length L of the m- cut wire, like the diameter D described above, directly affects the total weight and current density of the cut wire. When L is less than 0.5 mm, the workability is reduced and the cut wire is easily scattered by wind or the like. Further, in addition to the decrease in bulk density, the surface area tends to increase, and the amount of Cu to be applied and the amount of oil to be described later easily exceed appropriate amounts.
On the other hand, when L is 2D, that is, when it exceeds twice the diameter D of the cut wire, the current density becomes excessively large, and the arc start performance deteriorates. In addition, the filling property to the inner bottom of the groove is reduced.
Therefore, the wire length L of the cut wire is 0.5 to 2 Dmm
And

[0018] The Cu deposition amount _Cw (g) is
Divide by the weight G (g), and the obtained value (C _w / G) is 100
Doubled and expressed in percentage: 0.03% or more, preferred
Alternatively, by applying Cu to a cut wire strand of 0.25% or less , the electrical conductivity of the cut wire can be increased. However, if C _w / G is 0.
If it is less than 03%, the electric conductivity is insufficient, and the arc start property is deteriorated. Further, the rust resistance of the cut wire decreases, and when welding is performed using a cut wire that has generated rust, the amount of diffusible hydrogen in the weld metal increases rapidly. For this reason,
Hydrogen cracking resistance and porosity resistance are extremely deteriorated.

On the other hand, when C _w / G takes a large value,
Except for the point that economic efficiency is inferior, there is almost no possibility that various problems such as those caused by the cut wire coated with C at the time of segregation may occur, and a good arc start property can be obtained. Therefore, C
_Although it is not necessary to set the upper limit of _w / G,
C _w / G is preferably 0.25% or less in order to suppress the occurrence of component segregation even when the u-adhered layer is peeled off.

From the above, C _w / G needs to be 0.03% or more, and although the upper limit is not particularly limited,
Desirably, it is 0.25% or less. It should be noted that such a Cu-adhered layer can be formed by ordinary plating, but other methods may be used as long as the Cu-adhered layer that satisfies the above-mentioned weight range can be formed.

The total weight of the cut wire to oil amount Y _w (g)
G (g), multiply the obtained value ( _Yw / G) by 10 ⁶
A value expressed in ppm: 5 to 200 ppm In order to prevent rust, it is necessary to apply an appropriate amount of oil to the cut wire surface. If Y _w / G is less than 5 ppm, rust resistance becomes poor, and hydrogen cracking resistance and low-temperature cracking resistance decrease. On the other hand, if Y _w / G exceeds 200 ppm, the oil content on the wire surface is too large, so that the hydrogen cracking resistance and the porosity are deteriorated. In addition, the electric conductivity decreases, and the arc start property deteriorates. Therefore, Y _w / G is set to 5 to 200 ppm.

The measured value of the wire oil content is a value obtained by carbon tetrachloride extraction-non-dispersive infrared spectrometry specified in JIS.

The chemical composition of the cut wire is not particularly limited, and the cut wire is generally of the C—Mn— (Si) type, and Mo, Ni, Cr, Cu, Nb, V, etc. may be added as necessary. May be done.

Further, it is preferable to apply Cu to the cut wire and apply oil to the entire surface of the cut wire, that is, the outer peripheral surface and both end surfaces from the viewpoint of rust resistance and electric conductivity. However, in order to secure productivity, the above-described effects can be sufficiently obtained even when Cu is applied and oil is applied only to the outer peripheral surface of the cut wire.

[0025]

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a schematic view of a cut wire for welding according to an embodiment of the present invention. FIG. 1 (a) shows a cut wire in which the outer peripheral surface of the cut wire is coated with Cu and oil is applied, and FIG. The entire surface of the wire is coated with Cu and coated with oil. As shown in FIG. 1 (a), a Cu adhered layer 2 is formed on the outer peripheral surface of the cut wire 1, and oil is applied to the outer peripheral surface of the Cu adhered layer 2 to cut the cut wire 1. 3a are formed. The cut wire for welding configured as described above has high electric conductivity because Cu is adhered thereto, and thus has good arc start performance. Also, since oil is applied, rust resistance is good. For this reason, generation of hydrogen cracks and pores can be prevented.

Further, as shown in FIG. 1B, a cut wire obtained by forming a Cu coating layer 2 on the entire surface of the cut wire core material and further applying oil on the entire Cu coating layer 2 is obtained. 3b
Is a cut wire for welding with even better electrical conductivity and rust resistance.

In any of the above embodiments, the diameter D of the cut wire is set to 0.6 to 2.0 mm, and the length L of the cut wire is set to 0.5 to 2 Dmm. Further, Cu was deposited so that the value obtained by dividing the Cu deposition amount _Cw (g) of the cut wire by the total weight G (g) of the cut wire was 0.03% or more in percent. And the oil content Y _w (g) of the cut wire is calculated as the total weight G of the cut wire.
The value obtained by dividing by (g) is 5 to 20 in ppm.
Apply oil to 0 ppm.

Next, the results of welding performed by actually using the welding cut wire according to the embodiment of the present invention will be described in comparison with a comparative example. Example No. 1,
2, 5, 6 and Comparative Example Nos. The cut wire strands used in Examples 1, 3 and 4 and Example Nos. Nos. 3, 4 and Comparative Example Nos. Table 1 below shows the chemical components of the cut wire used in Example 2. Table 2 below shows the diameter D (mm) of the cut wire, the length L (mm) of the cut wire, the amount of Cu deposited, the amount of oil, and the rusting state in each of the examples and comparative examples.

[0029]

[Table 1]

[0030]

[Table 2]

In the above table, the Cu deposition amount is a value obtained by dividing the Cu deposition amount by the total weight of the cut wire, and the oil content is the oil content of the oil divided by the total weight of the cut wire. The values are shown in ppm. In addition, the rusting condition was such that the temperature of each cut wire was 30 ° C and the relative humidity was 80%.
The results of the investigation are shown after being left in a constant temperature and humidity room of RH for 7 days.

Using each cut wire having the above-described chemical composition and shape, the arc start property was examined. FIG.
FIG. 4 is a schematic diagram showing a method for investigating arc startability.
The filler 12 was sprayed on a base material 11a having a thickness of 12 mm in a circle having a diameter of 10 to 15 mm so as to have a thickness of 2 to 3 mm. The welding wire 13 was arranged substantially on the center of the filler 12, and after the flux was sprayed on the upper portion, the arc was started, and the arc startability at this time was investigated. The welding flux used is JISZ3
352 FS-FG3 having a particle size of 20 × D mesh and a welding wire conforming to JIS Z3351
It has a diameter of 4.8 mm specified in YS-S6.
Using this welding flux and wire, a current of 75
The welding was started at 0 A and a voltage of 36 V.

Further, each cut wire is filled in a groove,
After welding, weldability was investigated by an X-ray transmission test. FIG. 3 is a schematic diagram showing this welding method. The base material 11b having a thickness of 12 mm is abutted while forming a gap 17 having an interval of 5 mm, and a groove 14 having a groove angle of 50 °.
Are formed. The backing material 15 is in contact with the back side of the base material 11b so as to cover the lower part of the groove 14. Backing material 1
A recess 16 is formed in the center of the groove 5, and the groove 14 is formed.
A part of the filler 12 filled in the inside passes through the gap 17 and accumulates in the recess 16. After welding the inside of the groove 14 over 1000 mm, the weldability was examined by an X-ray transmission test. The welding flux used was JIS
Particle size specified in Z3352 FS-FG3 is 20 ×
D mesh and welding wire are JIS Z33
The diameter specified in 51YS-S6 is 4.8 mm. Using this welding flux and wire, the current is 750A, the voltage is 36V, and the welding speed is 23c.
The groove was welded under the condition of m / min.

The above-mentioned base materials 11a and 11b (JIS G)
Table 3 shows the chemical composition of 3106 SM-490A), Table 4 shows the chemical composition of the welding wire 13, and Table 5 shows the results of investigation on the arc start property and weldability of each cut wire.

[0035]

[Table 3]

[0036]

[Table 4]

[0037]

[Table 5]

In the welding in the groove, a cut wire left in a constant temperature and humidity room for 7 days was used.

As shown in Table 5 above, Example No. 1 to
The arc startability and weldability of No. 6 were both good.

On the other hand, in Comparative Example No. In No. 1, since the oil content was larger than the amount specified in the present invention and the ignitability was relatively low, the arc start property was deteriorated. Also, since the oil content was too large, blow holes were generated in the welding in the groove. Furthermore, since the diameter of the cut wire is smaller than the range specified in the present invention, the bulk density is reduced, and the wall thickness of the weld metal is insufficient.

Comparative Example No. In No. 2, since the oil content was less than the range specified in the present invention, red rust occurred on the cut wire after being left in a constant temperature and humidity chamber. Gas defects such as pits and blowholes frequently occurred in the weld metal.

Comparative Example No. Since the cut wire No. 3 had a Cu deposition amount smaller than the amount specified in the present invention, the ignitability was poor and the arc start performance was deteriorated. Also, pits and blowholes occurred frequently.

Comparative Example No. Since the diameter and the length of the cut wire of No. 4 were all larger than the ranges specified in the present invention, the ignitability deteriorated.

[0044]

As described above, the welding cut wire according to the present invention is covered with Cu and oil, and has an appropriate diameter and length. In addition to being usable as a material, it is possible to prevent high-temperature cracking due to C segregation, hydrogen cracking due to rusting, and welding defects such as blowholes.

Further, the cut wire for welding according to the present invention can be used as both an arc start material and a filling material in a groove, so that welding can be automated. In addition, since the complexity of inventory management can be reduced,
It is possible to prevent erroneous use due to mixing and equalization of a cut wire coated with a general cut wire.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a welding cut wire according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a method for investigating arc startability.

FIG. 3 is a schematic view showing a welding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1; Cut wire strand 2; Cu adhesion layer 3a, 3b; Cut wire 11a, 11b; Base material 12; Filler 13; Welding wire 14; Groove 15; Backing material 16;

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-6-262347 (JP, A) JP-A-6-297150 (JP, A) JP-A-57-199594 (JP, A) JP-A-63-1995 13696 (JP, A) JP-A-3-124391 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 35/36 B23K 9/18 B23K 25/00 B23K 35/02

Claims (6)

(57) [Claims] 1. A welding cut wire having a Cu coating layer formed thereon so as to cover the cut wire strand, and further applied with oil, wherein the diameter D of the cut wire is 0.6 to 2. 0 mm, length L in the longitudinal direction is 0.5 to 2 Dm
m, the value obtained by dividing the Cu deposition amount of the Cu deposition layer by the total weight of the cut wire is 0.03% or more as a percentage,
A cut wire for welding, wherein a value obtained by dividing an oil content of the oil by a total weight of the cut wire is 5 to 200 ppm in ppm. 2. The cut wire for welding according to claim 1, wherein a value obtained by dividing the amount of the deposited Cu by the total weight of the cut wire is 0.25% or less in percent. 3. The cut-off wire according to claim 1, wherein the Cu deposition layer is formed on the entire surface of the cut wire.
3. The cut wire for welding according to item 1. 4. The cut-off wire according to claim 1, wherein the Cu deposition layer is formed on a peripheral surface of the cut wire.
3. The cut wire for welding according to item 1. 5. The welding cut wire according to claim 3, wherein the oil is applied to an entire surface of the cut wire. 6. The welding cut wire according to claim 3, wherein the oil is applied to a peripheral surface of the cut wire.