JPH11320178A - Wire for gas shielded arc welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suit for the case where CO2 gas is used as a shield gas, reduce the generation volume of welding slag without deteriorating welding workability and mechanical performance of a welding material, and improve slag exfoliation property. SOLUTION: This wire for gas shielded arc welding comprises 0.03-0.10 wt.% C, 0.60-1.20 wt.% Si, 1.20-1.60 wt.% Mn, 0.010-0.025 wt.% S, 0.08-0.20 wt.% Ti, 0.020-0.100 wt.% Cr, and the balance of Fe and inevitable impurities. When the Si content in the wire is designated as [Si] at wt.% and the Mn content in the wire as [Mn] at wt.%, A being calculated by a formula A=[Si]/[Mn] is 0.40-0.90.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to mild steel or 490 (N
/ Mm ² ) class high-strength steel, using a carbon dioxide gas as a shielding gas, which is suitable for arc welding when using a gas shielded arc welding wire, and in particular, a gas shielded arc capable of reducing the occurrence of poor welding. It relates to a welding wire.

[0002]

2. Description of the Related Art Gas-shielded arc welding is rapidly spreading because it has a higher welding efficiency than a covered arc welding method and can be welded in combination with a welding robot. The welding method is large. Among them, multilayer welds such as steel joints and butt joints of bridge flanges can achieve deep penetration and excellent resistance to stomatal defects, and have a relatively small amount of slag generation and slag removal. In general, a gas-shielded arc welding method using a solid wire using carbon dioxide gas as a shielding gas is generally used in view of the fact that the number of labors for the welding can be reduced and the cost is low.

[0003] As a carbon dioxide gas shield welding wire, for example, in order to improve the slag properties such as slag removability and melting point, a gas shield in which the Mn and Si contents in the wire and their content ratios are adjusted. An arc welding wire has been proposed (JP-B-51-45543). In addition, the content of C, Si and Mn in the wire is specified, and the amount of slag is increased by adding Bi and S and Se or Te to the wire to improve the slag peelability. A shielded arc welding wire is also known (JP-A-3-399596).

Further, a wire for gas shielded arc welding has been proposed in which the slag removability is improved by regulating the contents of C, Si, Mn, Bi and B (Japanese Patent Laid-Open No. 6-182585). . Furthermore, C, Si, M
A gas-shielded arc welding wire in which the slag removability is improved by regulating the contents of Zr and V while defining the contents of n and Ti has also been proposed (Japanese Patent Application Laid-Open No. 55-64992). ). Incidentally, Japanese Patent Application Laid-Open No. 55-64
No. 992 describes that when a large amount of Ti is contained in a wire, the amount of slag generated increases and the slag removability decreases.

[0005]

However, any of the above-mentioned wires can improve the slag removability, but cannot sufficiently reduce the amount of slag generated during welding. Further, when the content of Ti in the wire is reduced in order to reduce the amount of slag generated, there is a problem that the amount of spatter generated during high-current welding is significantly increased.

When gas shielded arc welding is performed using, for example, a wire conforming to JIS Z3312YGW11 among the conventional wires for gas shielded arc welding, a continuous pass that can perform satisfactory welding without removing slag. The number is 5 to 6 passes, and the thickness of the material to be welded is about 25 mm or less. Therefore, as compared to the conventional gas shielded arc welding method, the slag removal process can be further reduced or the material to be welded having a thickness exceeding 25 mm can be unmannedly operated by a welding robot for gas shielded arc welding. Wire is required. For this purpose, it is required to further reduce the amount of slag generated during welding.

[0007] In gas shielded arc welding, a method for reducing the amount of slag generated is as follows.
A method using a mixed gas of 80% by volume of Ar gas and 20% by volume of CO ₂ gas, a method of using a mixed gas of 97% by volume of Ar gas and 3% by volume of O ₂ gas, or Ar gas; There is a method using a mixed gas of CO ₂ gas and O ₂ gas. These methods, by reducing the oxidizing,
This is to reduce the amount of oxide slag generated.

However, when a mixed gas is used as the shielding gas, there is a problem that the cost increases and the pore defect resistance decreases.

As described above, in the combination of the shielding gas composed of CO ₂ gas and the conventional wire, the welding workability such as the amount of spatter and the mechanical performance of the weld metal are equivalent to those at the time of welding using the conventional wire. In a state where the slag is more than that, the amount of slag generated can be sufficiently reduced, and good slag removability cannot be obtained.

The present invention has been made in view of such a problem, and is suitable for a case where CO ₂ gas is used as a shielding gas, without deteriorating welding workability and mechanical performance of a weld metal. It is an object of the present invention to provide a gas shielded arc welding wire capable of reducing the amount of welding slag and improving the slag peelability.

[0011]

The gas-shielding arc welding wire according to the present invention comprises: C: 0.03 to 0.10% by weight; Si: 0.60 to 1.20% by weight;
20 to 1.60% by weight, S: 0.010 to 0.02
5% by weight, Ti: 0.08 to 0.20% by weight and C
r: 0.020 to 0.100% by weight, the balance being Fe and unavoidable impurities, the content of Si is [Si] by weight%, and the content of Mn is [M] by weight%.
n], A calculated from the equation A = [Si] / [Mn] is 0.40 to 0.90.

[0012] The gas shielded arc welding wire according to the present invention further contains 0.0080% by weight or more of O,
It is preferable that O in the center of the wire except for a region from the wire surface to a depth of 0.01 mm is regulated to 0.0065% by weight or less based on the total weight of the wire.

Preferably, the content of Si is 0.70 to 1.20% by weight, and the content of Mn is 1.20 to 1.50% by weight. Further, the Ti
Is preferably 0.08 to 0.14% by weight,
It is even more preferable that A calculated by the above formula is 0.50 to 0.80.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors can reduce the amount of slag generated as compared with a conventional wire, and
In order to obtain a wire capable of improving slag peelability, various experimental studies were repeated. As a result, it has been found that the amount of slag generated can be reduced by appropriately adjusting the content ratio of Si and Mn, which are elements that generate slag. The reason why the amount of slag generation can be reduced by adjusting the Si content and the Mn content is not clear, but when the content of Si and Mn is within a predetermined range, the oxide of each element forms a complex. Since it does not form, it does not float in the molten metal as slag. Therefore, since each oxide remains in the weld metal, it is estimated that the amount of slag generated is reduced.

When the contents of Si and Mn are properly defined, the surface tension of the slag generated by using this wire becomes high, so that the slag is scattered in an island shape on the molten metal, and the iron of the bead is formed. The effect of increasing the ground exposure can be obtained.

Furthermore, the amount of slag can be reduced not only by adjusting the contents of Si and Mn but also by adding an appropriate amount of Cr to the wire. This is Cr
It is presumed that this oxide does not float as slag, and this oxide remains in the crystal grains of the weld metal or at the crystal grain boundaries.

Further, the present inventors have paid attention to the amount of oxygen in the wire itself, which is a supply source of oxygen other than the shielding gas. As a result, when the amount of oxygen in the wire is increased, the amount of slag generated is increased. Therefore, it has been found that it is preferable to reduce the amount of oxygen in the wire as much as possible. However, simply reducing the amount of oxygen in the wire decreases the arc stability and increases the amount of spatter generated.

Therefore, as a result of further experimental studies by the present inventors, it has been found that the amount of oxygen contained in the surface layer of the wire does not contribute to an increase in the amount of slag generated. The reason why the amount of oxygen in the surface portion of the wire does not contribute to the amount of slag generated will be described below. That is, the portion where the wire melted by the arc reacts with oxygen can be divided into a portion between droplet formation and droplet transfer and a surface at the time of formation of the molten pool. Among them, the contribution to the slag generation amount is large when the surface area is larger than the volume of the molten metal, that is, during the period from droplet formation to droplet transfer.

FIG. 1A is a plan view showing a droplet during transition.
1 (b) is a side view thereof, and FIG. 1 (c) shows the oxygen concentration on the vertical axis, and the horizontal axis shows the position along the line XX shown in FIGS. 1 (a) and 1 (b). FIG. 4 is a graph showing the relationship between oxygen concentration and position. As shown in FIGS. 1A to 1C, at a position along the line XX in the droplet 11, the oxygen concentration becomes extremely high in a region from the surface of the droplet 11 to 0.01 mm. ing. Thus, kinetically, the supply rate of oxygen is changed off the shield gas (B
ulk) to the droplet surface, the rate of chemical reaction between oxygen at the droplet surface and the elements in the droplet, and the oxide center to the droplet center (from the droplet center to the surface). Deoxidizing element)
Depends on the three types of mass transfer rates, of which
It is shown that the mass transfer of oxide to the droplet center is rate-limiting.

Therefore, when the oxygen content in the central portion of the wire is large, the oxidation reaction inside the droplet proceeds rapidly, and the amount of slag generated increases. On the other hand, in order to reduce the amount of slag generated, it is preferable to reduce the oxygen content at the center of the wire as much as possible.

However, even if oxygen distributed near the surface of the wire becomes a droplet, it is still distributed on the surface of the droplet and gradually diffuses into the droplet due to mass transfer such as convection. Since this mass transfer is rate-determining and the oxidation reaction on the droplet surface is in an equilibrium state, it does not affect the rate of oxide formation near the wire surface even if the oxygen concentration is high. Almost no.

On the other hand, as the total oxygen content including the wire surface is larger, the viscosity of the droplet is reduced, so that the stability of the droplet transfer and the workability of welding such as the reduction of the amount of spatter can be improved. .

From these facts, the inventors of the present invention have made it possible to increase the oxygen concentration in the surface portion of the wire and lower the oxygen concentration in the central portion of the wire without lowering the arc stability and the low spatterability. It has been found that the amount of slag generation can be reduced. As a result, the amount of slag generated can be significantly reduced as compared with a conventional wire without using a method such as Ti reduction (no addition) which has been effective for reducing the amount of slag generated, A wire having excellent welding workability can be obtained.

Hereinafter, the chemical components contained in the gas-shielded arc welding wire according to the present invention and the reasons for limiting the composition will be further described.

C: 0.03% to 0.10% by weight C is an element for securing the strength of the weld metal and is also one of the deoxidizing elements. In particular, unlike other elements such as Si and Mn, the oxide of C is released into the atmosphere as a gas like CO or CO ₂ , and therefore has a property of not forming slag. If the C content in the wire is less than 0.03% by weight, the strength of the weld metal for 490 N / mm ² grade steel cannot be secured. If the C content is less than 0.03% by weight, a sufficient deoxidizing effect cannot be obtained. On the other hand, if the C content in the wire exceeds 0.10% by weight, CO explosion becomes excessive, the amount of spatters generated increases, and welding workability decreases. Therefore, the C content in the wire is set to 0.03 to 0.10% by weight.

Si: 0.60 to 1.20% by weight, preferably
Specifically, 0.70 to 1.20% by weight Si is a main deoxidizing element and an element having an effect of improving the strength of the weld metal. When the Si content in the wire is less than 0.60% by weight, deoxidation becomes insufficient and blowholes are generated. On the other hand, if the Si content in the wire is less than 0.60% by weight, the familiarity of the bead becomes poor, and the appearance of the bead deteriorates. On the other hand, S in the wire
When the i content exceeds 1.20% by weight, the strength becomes excessive or the toughness is reduced, and the amount of slag generated is increased. Therefore, the Si content in the wire is set to 0.60 to 1.20% by weight. Preferably, the Si content in the wire is 0.70 to 1.20% by weight.

Mn: 1.20 to 1.60% by weight, preferably
Alternatively, 1.20 to 1.50% by weight Mn, like Si, is an element having a main deoxidizing effect and an effect of improving the strength of the weld metal. When the Mn content in the wire is less than 1.20% by weight, deoxidation becomes insufficient and blowholes are generated. Further, if the Mn content in the wire is less than 1.20% by weight, a weld metal having desired strength and toughness cannot be obtained. On the other hand, when the Mn content in the wire is 1.
If it exceeds 60% by weight, the amount of slag generated increases and the slag removability deteriorates. Therefore, Mn in the wire
The content is 1.20 to 1.60% by weight. Preferably, the Mn content in the wire is 1.20 to 1.5.
0% by weight, whereby the amount of slag generated can be further reduced.

Calculated by the formula A = [Si] / [Mn]
A: 0.40 to 0.90, preferably 0.50
The ratio between the Si content and the Mn content in the 0.80 to 0.80 wire significantly affects the amount of slag generated and the slag removability. The Si content in the wire is [Si] by weight%, and the Mn in the wire is
When the content is expressed as [Mn] in weight%, the formula A = [S
If A calculated by [i] / [Mn] is less than 0.40, the amount of slag generation increases and the composition ratio of Mn oxide increases, so that a porous and thick slag is formed. . When A is less than 0.40, the interfacial energy between the slag and the iron decreases, the slag peeling property decreases, and the slag covers the entire bead surface,
Iron exposure is reduced. On the other hand, when A exceeds 0.90,
As the amount of slag generated increases and the composition ratio of the Si oxide increases, glassy slag having a high melting point is obtained.
As a result, the slag is less likely to melt in the welding arc of the next pass, and slag winding defects are more likely to occur. Further, when the glass-like slag is formed, the appearance of the bead after the slag is separated deteriorates. Therefore, A calculated by the above formula is 0.40 to 0.90, and in this range, the amount of slag generated is small, and the generated slag has good removability. Preferably, A is 0.50 to 0.80.

S: 0.010 to 0.025% by Weight S is an element having the effect of reducing the surface tension of the molten metal and improving the conformability of the bead toe. Also,
S in the wire does not affect the amount of slag,
As the S content in the slag increases, the effect of coagulating the slag can be obtained, and the iron base on the bead surface can be exposed. The more exposed the iron material on the bead surface, the easier the arc is generated, and the more easily the slag can be peeled off. If the S content in the wire is less than 0.010% by weight, these effects cannot be sufficiently obtained. On the other hand, if the S content in the wire exceeds 0.025% by weight, the resistance to hot cracking of the weld metal decreases. Therefore, the S content in the wire is set to 0.010 to 0.025% by weight.

Ti: 0.08 to 0.20% by weight, preferably
In other words, 0.08 to 0.14% by weight Ti is an element having the effect of stabilizing the globule transfer of droplets and significantly reducing the amount of spatter generated in high current welding. However, the addition of Ti into the wire increases the amount of slag generated. In the present invention,
By appropriately defining the content of other components other than Ti, the amount of slag generated is reduced.
It is not necessary to sufficiently reduce the i content. Ti in wire
If the content is less than 0.08% by weight, the effect of arc stability cannot be obtained. On the other hand, if the content of Ti in the wire exceeds 0.20% by weight, the effect of increasing the amount of slag cannot be suppressed even if the content of components other than Ti is appropriately adjusted, and the slag removability is also reduced. Also gets worse. Therefore, the Ti content in the wire is 0.08 to 0.5.
20% by weight. Preferably, Ti in the wire
The content is 0.08 to 0.14% by weight, whereby the amount of slag generation can be further reduced.

Cr: 0.020 to 0.100 wt% Cr has a lower affinity for oxygen than Si and Mn, but is an element that forms an oxide. Since the Cr oxide does not become slag but remains in the weld metal, a very small amount of Cr
Is added to the wire, an effect of reducing the amount of slag generated can be obtained. If the Cr content in the wire is less than 0.020% by weight, the effect of reducing the amount of slag generated cannot be sufficiently obtained. On the other hand, Cr
Is contained in a large amount exceeding 0.100% by weight, the strength of the weld metal becomes excessive and the inclusions become excessive, resulting in a decrease in the toughness of the weld metal. Therefore, the Cr content in the wire is set to 0.020 to 0.100% by weight.

O: 0.0080% by weight or more , excluding a region from the wire surface to a depth of 0.01 mm
O in center of ear: 0.0065 weight per total weight of wire
% Or less The smaller the amount of oxygen in the wire, the more the amount of slag generated can be reduced. On the other hand, the more oxygen in the wire,
Arc stability is improved. However, what affects the amount of slag generated is the amount of oxygen in the center of the wire, and the amount of oxygen existing in the surface layer of the wire (the area from the wire surface to a depth of 0.01 mm) has little effect on the generation of slag. do not do. Therefore, in the present invention, in order to obtain a welding wire that satisfies both a reduction in the amount of slag generation and an improvement in arc stability, the oxygen content in the wire is defined separately for the central portion of the wire and the surface portion of the wire. I do. However, since it is difficult to measure the amount of oxygen in the surface portion of the wire by weight%, in the present invention, the O (oxygen) content of the entire wire and the central portion of the wire (the surface portion of the wire was removed from the entire wire). Region) and the O content.

When the O content at the center of the wire exceeds 0.0065% by weight based on the total weight of the wire, the effect of sufficiently reducing the amount of slag cannot be obtained. On the other hand, if the total oxygen content in the wire is less than 0.0080% by weight, good arc stability cannot be obtained. Therefore, the O content in the wire is set to 0.0080% by weight or more, and the O content in the center portion of the wire (excluding the area from the wire surface to a depth of 0.01 mm) is set to 0.0065% by weight or less. In addition, as a method for controlling the oxygen concentration in the central portion of the wire and the surface portion of the wire, a material having a lower O content than the specified value in the central portion is selected to prepare a wire material, and when the wire material is annealed, the annealing atmosphere is changed. There is a method of adjusting and oxidizing the surface of the wire material to make the O content of the entire wire 0.0080% by weight or more.

In the present invention, components other than the above-mentioned components and iron are not intentionally added to the wire. However, as an impurity level, P is 0.020% by weight or less, Al, Ni, and Nb. , V, and Zr are each 0.05% by weight or less, and B is 0.0010% by weight or less, since it does not particularly affect the wire of the present invention, so that it is acceptable. In addition, Cu as a solid wire
The presence or absence of plating is not particularly specified because it does not affect the wire of the present invention.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the gas shielded arc welding wire according to the present invention will be specifically described in comparison with comparative examples.

First, various wires were prepared by changing only the Si content and the Mn content in the wires and their ratios, and the base metal was welded using these wires under the welding conditions shown in Table 1 below. Then, the amount of slag generated was measured. FIG.
FIG. 2 is a schematic diagram showing the shape of a welding base material and a lamination method when measuring the amount of slag generated. As shown in FIG. 2, two steel plates 12 having inclined end surfaces and having a thickness of 28 mm
The inclined end faces are arranged to face each other, and
Was placed. The root interval is 7 mm and the groove angle is 3
5 mm. Then, after forming the weld metal 14 by performing gas shield arc welding on the formed groove, the generated slag was sampled, and the amount of slag generated per unit length in the welding direction was measured. In FIG. 2,
The numbers shown in the weld metal indicate the order of lamination of the weld metal laminated by each pass.

[0037]

[Table 1]

FIG. 3 shows the slag generation amount on the vertical axis, and the ratio of the Si content to the Mn content ([Si] / [Mn]) on the horizontal axis.
FIG. 3 is a graph showing a relationship between a slag generation amount and a content ratio of Si and Mn. As shown in FIG. 3, in the range Y ([Si] / [Mn]: 0.4 to 0.9) of the present invention, the amount of slag generated is 0.35 g / cm or less, and the amount of slag generated is reduced. I was able to. In a preferred range Z ([Si] / [Mn]: 0.5 to 0.8) of the present invention, the amount of slag generated is 0.25 g / c.
m or less, and the amount of slag generation was further reduced.

Next, using various wires, the above Table 1 was used.
The base metal was welded under the welding conditions shown in FIG. 2 and the amount of slag generated was measured, and the integrity of the weld metal, the strength of the weld metal, and the Charpy absorbed energy by X-ray radiography and ultrasonic testing (UT) were measured. It was measured. The slag peelability, bead appearance and arc stability were evaluated organoleptically. Furthermore, welding was performed under the welding conditions shown in Table 2 below, and the amount of generated spatter was measured.

[0040]

[Table 2]

FIG. 4 is a perspective view showing a method for measuring the amount of spatter generated. The steel plate 15 was arranged with its longitudinal direction being horizontal, and spatter collection boxes 16 were installed on both sides. The sputter collection box 16 has an opening (not shown) on a surface that contacts the steel plate 15. Then, while welding the upper surface of the steel plate 15, the torch 17 is moved in the welding direction 19, and the spatter 18 generated by welding is collected inside the collection box 16,
The amount of spatter generation was calculated by measuring the weight increase of the collection box 16. The compositions of the wires of the examples and comparative examples are shown in Tables 3 to 6 below, and the evaluation results are shown in Tables 7 to 1 below.
0 is shown. In the wire compositions shown in Tables 3 to 6 below, the O content at the center of the wire is measured by grinding the surface layer from the surface of the wire to a depth of 100 to 110 μm and measuring the O content at the remaining portion. Was obtained.

Further, in Tables 7 to 10 below, the amount of slag generation is a value obtained by collecting all slag after welding, weighing it, and converting it per unit welding length (total slag amount / 40).
cm), and when it is less than 0.25 g / cm, it is extremely good, and 0.25 g / cm or more and 0.35 g / cm.
If the value is less than 0.35 g / cm, it is regarded as good. The slag removability, arc stability, and bead appearance were evaluated on a three-point scale from good to poor, ◎ was extremely good, ○ was good, and x was poor.

Further, regarding the tensile strength, 490 N / m
The range is considered to be appropriate as a welding wire for m ² grade steel, and if it is 490 to 600 N / mm ² , it is acceptable, and if it is less than 490 N / mm ² or 600 N / m 2
a case in which more than m ² was rejected. Regarding the absorbed energy, a case where the energy was 47 J or more at 0 ° C. was regarded as a pass, and a case where the energy was less than 47 J was rejected. Regarding the soundness of the weld metal by the X-ray transmission test and the ultrasonic flaw detection test, one in which no defects such as cracks, poor fusion, slag entrainment and blow holes were generated was accepted, and at least one of these was confirmed. Things were rejected. Regarding the amount of spatter generated, the case where the amount is less than 1.50 g / min is extremely good, the case where the amount is 1.50 g / min or more and less than 2.00 g / min is good, and the case where the amount is 2.00 g / min or more. Was regarded as defective.

[0044]

[Table 3]

[0045]

[Table 4]

[0046]

[Table 5]

[0047]

[Table 6]

[0048]

[Table 7]

[0049]

[Table 8]

[0050]

[Table 9]

[0051]

[Table 10]

As shown in Tables 3 to 10 above, Example N
o. 1 to 14 are composition of wire, Si content and Mn.
Since the ratio to the content was appropriately adjusted, the amount of slag generated was small, and the slag removability and bead appearance were excellent. In addition, welding defects such as pore defects and cracks did not occur, and a sound weld metal could be obtained. Furthermore, the strength and toughness of the weld metal are good,
The arc stability was good and the amount of spatter generated was small. In particular, in Example No. 4 to 14
Since the O content of the entire wire and the O content of the central portion of the wire are appropriately adjusted, the arc stability can be further improved, and the amount of slag generated can be further reduced.

On the other hand, in Comparative Example No. In No. 15, since the C content in the wire exceeded the upper limit of the range of the present invention, CO explosion increased and the amount of fine spatters increased. Also,
Since the Cr content in the wire exceeded the upper limit of the range of the present invention, the strength of the weld metal became excessive and the toughness was lowered. Comparative Example No. 16 is a general JIS Z331
2 Although it is one type of wire conforming to YGW11, the amount of slag is increased because the Mn content in the wire exceeds the upper limit of the present invention and the Cr content is less than the lower limit of the present invention. However, the slag removability also decreased. Comparative Example No. In No. 17, since the contents of C and Mn in the wire were less than the lower limit of the range of the present invention, the hardenability was reduced, the strength of the weld metal was reduced to 490 N / mm ² or less, and the toughness was reduced. In addition, blow holes were generated due to insufficient deoxidation.

Comparative Example No. 18 is Si and S in the wire
Since the content exceeds the upper limit of the range of the present invention, the strength of the weld metal becomes excessive and the toughness is insufficient. Also,
Hot cracking occurred when the S content in the wire exceeded the upper limit of the range of the present invention. Further, since A calculated from [Si] / [Mn] exceeds the upper limit of the range of the present invention,
The amount of slag generated increased, the slag became vitreous, slag entrainment defects occurred, and the bead appearance deteriorated. Comparative Example No. In No. 19, since the content of Si and S in the wire was less than the lower limit of the range of the present invention, the familiarity of the bead became poor and the bead appearance was deteriorated. In addition, S in the wire
Since the i content was less than the lower limit of the range of the present invention, deoxidation was insufficient and blowholes occurred. Furthermore, [Si] / [M
n] is less than the lower limit of the range of the present invention, so that the amount of slag generated increased and the slag removability deteriorated.

Comparative Example No. In No. 20, although the contents of Si and Mn were within the range of the present invention, the amount of slag generated increased because A calculated from [Si] / [Mn] exceeded the upper limit of the range of the present invention. Also, the slag becomes glassy,
A slag entrainment defect occurred and the bead appearance deteriorated. Comparative Example No. 21 is Si and Mn in the wire
Although the content is within the scope of the present invention, [Si] / [Mn]
Since A calculated from is below the lower limit of the present invention range and the Ti content exceeds the upper limit of the present invention range,
As the amount of slag generated increased, the slag peelability decreased.

Comparative Example No. In No. 22, since the content of Ti, which is an element for improving the arc stability in the wire, was less than the lower limit of the range of the present invention, the generation amount of slag was reduced, but the generation amount of spatter was significantly increased. In addition, Cr in the wire
Since the content exceeds the upper limit of the range of the present invention, the strength of the weld metal becomes excessive and the toughness decreases. Comparative Example No. In No. 23, the Mn content in the wire exceeded the upper limit of the present invention, and the A and Cr contents calculated from [Si] / [Mn] were less than the lower limit of the present invention.
Since the deoxidizing effect by r could not be obtained, the amount of slag generated increased. Also, since the Si content in the wire was less than the lower limit of the present invention, blowholes were generated due to insufficient deoxidation. Furthermore, since the content of Si and S in the wire was less than the lower limit of the range of the present invention, the familiarity of the bead became poor, and the bead appearance also deteriorated. Furthermore, Mn in slag
Since the oxide ratio was high, the removability of the slag was reduced.

Comparative Example No. 24 indicates C and S in the wire
Since the i content exceeds the upper limit of the present invention and the Mn content in the wire is less than the lower limit of the present invention,
As the strength of the weld metal became excessive, the toughness decreased. Further, since A calculated from [Si] / [Mn] exceeds the upper limit of the range of the present invention, the amount of slag generated increases, the slag becomes vitreous, slag entrainment defects occur, and beads are formed. The appearance of deteriorated. Comparative Example N
o. In No. 25, the strength of the weld metal became excessive because the C content in the wire exceeded the upper limit of the range of the present invention. Also,
Since the Ti content in the wire was less than the lower limit of the range of the present invention, the stability of the arc was reduced, and the amount of spatter generated was extremely large.

[0058]

As described in detail above, according to the present invention,
Since the composition of the wire is properly defined and the ratio between the Si content and the Mn content is appropriately defined, the welding performance such as mechanical performance and defect resistance of the weld metal and spatter generation is improved. Without lowering, the amount of slag generated can be reduced and the slag removability can be improved. When O is contained in the wire,
When the O content and the O content at the center of the wire are strictly defined, a gas-shielded arc welding wire that can further reduce the amount of slag and improve the stability of the arc can be obtained. be able to. Thereby, in the case of continuous welding, the maximum thickness required to remove slag increases, and the number of slag removal steps can be reduced. Therefore, the welding operation is facilitated and the efficiency of the welding process can be significantly improved, so that a great industrial value can be obtained.

[Brief description of the drawings]

1 (a) is a plan view showing a droplet during transition, FIG. 1 (b) is a side view thereof, FIG. 1 (c) is an oxygen concentration on the vertical axis, and FIG. It is a graph which shows the relationship between oxygen concentration and a position which takes the position along XX shown to 1 (b).

FIG. 2 is a schematic diagram showing a shape of a welding base material and a lamination method when measuring a slag generation amount.

FIG. 3 shows a slag generation amount on a vertical axis and a ratio ([Si] / [Mn]) of a Si content and a Mn content on a horizontal axis.
It is a graph which shows the relationship between the amount of slag generation, and the content ratio of Si and Mn.

FIG. 4 is a perspective view showing a method for measuring a sputter generation amount.

[Explanation of symbols]

 11; droplets 12, 15; steel plate 13; backing material 14; weld metal 16; spatter collection box 17; torch 18;

Claims (6)

[Claims] 1. C: 0.03 to 0.10% by weight, S
i: 0.60 to 1.20% by weight, Mn: 1.20 to 1.60% by weight, S: 0.010 to 0.025% by weight, Ti: 0.08 to 0.20% by weight, and Cr: 0.
020 to 0.100% by weight, with the balance being Fe and unavoidable impurities. When the content of Si is [Si] in weight% and the content of Mn is [Mn] in weight%, A gas shielded arc welding wire characterized in that A calculated by the formula A = [Si] / [Mn] is 0.40 to 0.90. 2. The composition according to claim 2, further comprising 0.0080% by weight of O, and excluding the region from the surface of the wire to a depth of 0.01 mm, O at the center of the wire is 0.00% of the total weight of the wire.
The gas shielded arc welding wire according to claim 1, wherein the wire is regulated to 65% by weight or less. 3. The Si content is 0.70 to 1.20% by weight.
The gas-shielded arc welding wire according to claim 1, wherein: 4. The Mn content is 1.20 to 1.50% by weight.
The gas shielded arc welding wire according to any one of claims 1 to 3, wherein: 5. The Ti content is 0.08 to 0.14% by weight.
The gas shielded arc welding wire according to any one of claims 1 to 4, wherein: 6. The gas shielded arc welding wire according to claim 1, wherein A is 0.50 to 0.80.