Wire for gas shielded arc welding

Abstract

Provided is a wire for gas shielded arc welding. 【Solution】The wire for gas shielded arc welding of the present invention comprises, by weight %, C: 0.001 to 0.30%, Si: 0.25% or less (excluding 0%), Mn: 0.50 to 3.00%, P: 0.030% or less (excluding 0%), S: 0.030% or less (excluding 0%), Cr: 0.50% or less (excluding 0%), Mo: 0.60% or less (excluding 0%), Al: less than 0.10% (excluding 0%), Ni: 0.40% or less (excluding 0%), Cu: 0.50% or less (excluding 0%), Ti: less than 0.10% (excluding 0%), the balance being Fe and other inevitable impurities, and is characterized by satisfying the following relational expressions 1 and 2. [Relational expression 1] 2.0 ≤ [Si] × 100 / [Mn] ≤ 5.2 [Relational expression 2] [Ti] + [Al] < 0.10 (In the above relational expressions 1 and 2, [Si], [Mn], [Ti], and [Al] represent the weight % content of each element in parentheses with respect to the welding wire)

Description

Technical Field

[0001] The present invention relates to a wire for gas shielded arc welding, and more particularly to a wire for gas shielded arc welding that is not only excellent in welding joint strength and porosity resistance but also can ensure the economy that is essentially required during component manufacturing.

Background Art

[0002] In the automotive field, due to policies on fuel consumption regulations for environmental protection such as the global warming problem, research on technologies for reducing the weight of vehicle bodies and components has emerged as a major issue. For chassis components that are important for vehicle driving performance, it is also necessary to apply high-strength steel materials for weight reduction under such a general trend. In order to achieve such component weight reduction, it is essential to increase the strength of the material, and it can be said that ensuring the durability performance of components made of high-strength steel materials in an environment where repeated fatigue loads are applied is an important factor.

[0003] However, when assembling automotive chassis components, in the case of arc welding mainly used to ensure strength, since the lap joint welding between components is performed by welding the welding wire, it is inevitable to give the geometric shape of the joint. This acts as a concentration part (notch effect) of repeated fatigue stress and becomes a fracture origin, resulting in a decrease in the durability performance of the component. For this reason, there is a limit to the application of high-strength steel materials.

[0004] Therefore, in order to improve the fatigue characteristics of the welded part, it is most important to mainly reduce the angle (toe angle) of the bead tip, which is the stress concentration part. In addition to this, it can be said that controlling the material and stress of the toe part are important factors. Also, as described above, due to the trend of high-strengthening and weight-saving of parts and the thinning of the material, the requirement for rust prevention performance to prevent through corrosion has increased, and the adoption of plated steel sheets has increased. However, there is no plating layer in the weld metal of the arc welded part in particular, and there is a risk that the corrosion resistance after painting with respect to the base material will deteriorate. As a result, in the harsh corrosion environment during vehicle driving, there is a problem that it leads to a decrease in fatigue characteristics along with the occurrence of early corrosion in the welded part of the chassis parts made of plated steel sheets. On the other hand, during the gas shielded arc welding of plated steel materials, due to the generation of vapors such as zinc, a large amount of pore defects in the form of pits and blowholes occur in the weld bead, which may lead to a decrease in the strength of the welded part. As a result, the welding productivity decreases, which has become a problem. Also, in the case of general unplated steel materials, during gas shielded arc welding, the slag generated on the weld bead causes poor painting and becomes a factor in the decrease in corrosion resistance after painting. Therefore, there is a problem that the cost increases due to post-treatment processes such as pickling or brushing for removing slag after welding during part manufacturing.

[0005] Recently, the development of lightweight chassis parts for next-generation eco-cars has been actively carried out, and in particular, the development of welding technologies that can improve the characteristics of welded parts while ensuring economic efficiency has become an important issue.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a wire for gas shielded arc welding excellent in weld strength and porosity resistance that can ensure excellent strength and porosity resistance of welded metal in the field of the automobile industry. The problems of the present invention are not limited to the above matters. Further problems of the present invention are described in the entire content of the specification, and those having ordinary knowledge in the technical field to which the present invention pertains will have no difficulty in understanding the further problems of the present invention from the entire content of the specification of the present invention.

Means for Solving the Problems

[0008] The wire for gas shielded arc welding of the present invention contains, by weight%, C: 0.001 to 0.30%, Si: 0.25% or less (excluding 0%), Mn: 0.50 to 3.00%, P: 0.030% or less (excluding 0%), S: 0.030% or less (excluding 0%), Cr: 0.50% or less (excluding 0%), Mo: 0.60% or less (excluding 0%), Al: less than 0.10% (excluding 0%), Ni: 0.40% or less (excluding 0%), Cu: 0.50% or less (excluding 0%), Ti: less than 0.10% (excluding 0%), the balance being composed of Fe and other inevitable impurities, and is characterized by satisfying the following relational expressions 1 and 2. [Relational Expression 1] 2.0 ≦ [Si] × 100 / [Mn] ≦ 5.2 [Relational Expression 2] [Ti] + [Al] < 0.10 (In the above relational expressions 1 and 2, [Si], [Mn], [Ti], and [Al] represent the weight% content of each element in parentheses with respect to the welding wire.)

[0009] The above welding wire preferably contains Si in the range of 0.05 to 0.09%. The above welding wire can further contain one or more of Nb: 0.10% or less, V: 0.10% or less, and Zr: 0.10% or less. The above welding wire preferably further contains B: 0.01% or less. The above welding wire can be a solid wire, a metal cored wire, or a flux cored wire.

[0010] The welded metal of the present invention is a welded metal obtained by welding a base metal to be welded using the above welding wire, and the length fraction occupied by pore defects in the welded metal satisfies 10% or less (including 0%) with respect to the total length of the welded metal.

Effect of the Invention

[0011] According to the present invention, as a next-generation welding technology that secures performance / cost competitiveness in line with the popularization era of electric vehicles, it is possible to effectively provide a gas shielded arc welding wire excellent in welding part strength and porosity resistance.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0013] Hereinafter, the present invention will be described. When welding galvanized steel sheets, there is a problem that porosity defects occur in the welded part due to the generation of zinc vapor. At this time, when the Si content, which is a deoxidizer in the wire component, is reduced below a certain level, the viscosity of the molten metal decreases, the discharge of zinc vapor becomes smooth, and O generated by the dissociation of CO2 in the shielding gas at the high temperature during welding reacts more actively with Zn in the plating layer. As ZnO-based oxides are formed, the zinc vapor pressure can be effectively reduced to stabilize the arc and suppress the occurrence of porosity defects. However, when Ti or Al, which is a steel deoxidizer in the wire component, is contained in a content of a certain level or more, the above-mentioned oxidation reaction of Zn is hindered, and even with a low Si content, arc instability, an increase in porosity defects, and a decrease in the strength of the welded part are caused, as confirmed through the research results of the present inventors. In particular, when the Ti + Al value is 0.10% or more, an increase in porosity defects is obvious, and it was confirmed that a weld metal having excellent welded part strength and porosity resistance cannot be ensured.

[0014] Therefore, the wire for gas shielded arc welding of the present invention preferably consists of, by weight%, C: 0.001 to 0.30%, Si: 0.25% or less (excluding 0%), Mn: 0.50 to 3.00%, P: 0.030% or less (excluding 0%), S: 0.030% or less (excluding 0%), Cr: 0.50% or less (excluding 0%), Mo: 0.60% or less (excluding 0%), Al: less than 0.10% (excluding 0%), Ni: 0.40% or less (excluding 0%), Cu: 0.50% or less (excluding 0%), Ti: less than 0.10% (excluding 0%), with the balance being Fe and other inevitable impurities, and satisfies the following relational expressions 1 and 2. [Relational Expression 1] 2.0 ≤ [Si] × 100 / [Mn] ≤ 5.2 [Relational Expression 2] [Ti] + [Al] < 0.10

[0015] Hereinafter, the wire for gas shielded arc welding according to an embodiment of the present invention will be described. First, in the wire of the present invention, the reasons for adding each component and the reasons for limiting the content will be described in detail. The content of each component is based on weight% unless otherwise specified.

[0016] C: 0.001 to 0.30% The above C is an element that is advantageous for stabilizing the arc and atomizing the droplets, and is also advantageous for ensuring hardening ability. When the content of the above C is less than 0.001%, the droplets become coarser, the arc becomes unstable, not only does the amount of spatter generated increase, but there is also a drawback that it becomes difficult to ensure sufficient strength of the weld metal. On the other hand, when it exceeds 0.30%, the viscosity of the molten metal decreases, not only does the bead shape become poor, but there is also a risk of over-hardening the weld metal and reducing its toughness.

[0017] Si: 0.25% or less (excluding 0%) The above Si is an element that is advantageous for suppressing the generation of blowholes as an element (deoxidizing element) that promotes deoxidation of the molten metal during arc welding. However, during welding of galvanized steel sheets, by reducing the Si content, oxidation of Zn can be promoted, the zinc vapor pressure can be lowered, and the generation of pore defects in the weld zone can be prevented. Also, by reducing the Si content and strengthening the arc force due to a decrease in the specific resistance of the wire, the discharge of zinc vapor from the molten metal directly under the arc can be promoted. On the other hand, when the content of the above Si exceeds 0.25%, a large amount of non-conductive slag is generated, causing poor painting of the weld zone, and there is a risk that the surface activation of the weld zone is insufficient due to excessive deoxidation and the wettability of the molten metal decreases. Therefore, in the present invention, it is preferable to control the Si content to 0.25% or less. More preferably, it is to control the above Si content in the range of 0.05 to 0.09%. When the content of the above Si is too small, there is a risk that the deoxidation effect is insufficient and blowholes are likely to occur.

[0018] Mn: 0.5 to 3.0% The above Mn is a deoxidizing element, which is an element that promotes the deoxidation of molten metal during arc welding and is advantageous for suppressing the generation of blowholes. If the content of the above Mn is less than 0.5%, there may be a drawback that the deoxidation effect is insufficient and the generation of blowholes becomes easy. However, during the welding of galvanized steel sheets, when the content of Mn is excessively high, it may prevent the oxidation of Zn, increase the zinc vapor pressure, and promote the occurrence of arc instability and porosity defects in the welded part. On the other hand, if it exceeds 3.0%, the viscosity of the molten metal becomes excessively high. When the welding speed is fast, the molten metal cannot flow appropriately into the welding part, and a humping bead is formed, so there is a risk that bead shape defects are likely to occur. More preferably, the content of the above Mn is limited to 2.5% or less.

[0019] Cr: 0.50% or less (excluding 0%) The above Cr is a ferrite stabilizing element, which is an element that is advantageous for ensuring the hardening ability to improve the strength of the weld metal. If the content of the above Cr exceeds 0.50%, in some cases, the brittleness of the weld metal may increase unnecessarily, and it may be difficult to ensure sufficient toughness. The content of the above Cr is preferably 0.30% or less, more preferably 0.20% or less, and even more preferably 0.10% or less.

[0020] Mo: 0.60% or less (excluding 0%) The above Mo is a ferrite stabilizing element, which is an element that is advantageous for ensuring the hardening ability to improve the strength of the weld metal. If the content of the above Mo exceeds 0.60%, in some cases, the toughness of the weld metal may decrease.

[0021] P: 0.030% or less (excluding 0%) The above P is an element that generally enters the steel as an inevitable impurity, and is also included as a normal impurity in the solid wire for arc welding. If the content of the above P exceeds 0.030%, there is a risk that hot cracks in the weld metal become prominent.

[0022] S: 0.030% or less (excluding 0%) [[ID=2,3]] The above S is an element that generally mixes into steel as inevitable impurities and is also an element contained as ordinary impurities in solid wires for arc welding. When the content of the above S exceeds 0.030%, in some cases, the toughness of the weld metal deteriorates, the surface tension of the molten metal during welding is insufficient, and when performing high-speed downhand welding (welding from top to bottom during vertical welding), the molten part may flow down excessively due to gravity, resulting in a poor shape of the weld bead.

[0023] Al: Less than 0.10% (excluding 0%) The above Al is an element that can improve the strength of the weld metal by promoting the deoxidation of the molten metal during arc welding even in trace amounts as a deoxidizing element. To ensure the above-mentioned effects, 0% is excluded as the lower limit of the Al content. However, due to the deoxidation effect of Al, during the welding of galvanized steel sheets, it may interfere with the oxidation reaction of Zn, promoting the generation of porosity defects in the weld due to an increase in Zn vapor pressure and the induction of arc instability. When the content of the above Al is 0.10% or more, the generation of Al-based oxides increases, and in some cases, the strength and toughness of the weld metal may decrease, leading to poor electrocoating of the weld due to non-conductive oxides.

[0024] Ti: Less than 0.10% (excluding 0%) The above Ti is an element that can improve the strength of the weld metal by promoting the deoxidation of the molten metal during arc welding even in trace amounts as a deoxidizing element. It also facilitates the development of acicular ferrite that can improve the toughness of the weld. To ensure the above-mentioned effects, 0% is excluded as the lower limit of the Ti content. However, due to the deoxidation effect of Ti, during the welding of galvanized steel sheets, it may interfere with the oxidation reaction of Zn, promoting the generation of porosity defects in the weld due to an increase in Zn vapor pressure and the induction of arc instability. When the content of the above Ti is 0.10% or more, the generation of Ti-based oxides increases, and in some cases, the strength and toughness of the weld metal may decrease.

[0025] Ni: 0.40% or less (excluding 0%) The above-mentioned Ni is an element that can improve the strength and toughness of the weld metal. To ensure the above-described effects, 0% is excluded as the lower limit of the Ni content. However, if the content of the above-mentioned Ni exceeds 0.40%, there is a drawback that it becomes sensitive to cracks, so the Ni content is set to 0.40% or less. The content of the above-mentioned Ni is preferably 0.30% or less, more preferably 0.20% or less, and even more preferably 0.10% or less.

[0026] Cu: 0.50% or less (excluding 0%) The above-mentioned Cu is generally contained at about 0.02% as an impurity in the steel forming the wire. However, in the case of the solid wire for arc welding, its content can be determined mainly due to the copper plating applied to the surface of the wire. The above-mentioned Cu is an element that can stabilize the wire feeding property and the electrical conductivity. However, if the content of the above-mentioned Cu exceeds 0.50%, there is a drawback that the crack sensitivity of the weld metal becomes high. The content of the above-mentioned Cu is preferably 0.45% or less, more preferably 0.40% or less, and even more preferably 0.30% or less. And the welding wire of the present invention can selectively further contain one or more of Nb: 0.10% or less, V: 0.10% or less, and Zr: 0.10% or less.

[0027] Nb: 0.10% or less The above-mentioned Nb is an element that can enhance the hardening ability, make the microstructure dense, and improve the strength and toughness of the weld metal. In addition, it has the effect of improving the flow of the molten metal during arc welding and stabilizing the arc. To ensure the above-described effects, 0% is excluded as the lower limit of the Nb content. However, if the content of the above-mentioned Nb exceeds 0.10%, there is a possibility that a low melting point compound is formed at the grain boundary and hot cracks are likely to occur.

[0028] V: 0.10% or less The above V is an element that can enhance the hardening ability, make the microstructure dense, and improve the strength and toughness of the weld metal. It is also a precipitation strengthening element that can generate carbonitrides to improve the strength of the weld metal. However, when the content of the above V exceeds 0.10%, there is a risk that the toughness of the weld metal may decrease in some cases due to excessive strength caused by excessive precipitates. Therefore, the content of the above V is set to 0.10% or less.

[0029] Zr: 0.10% or less The above Zr is an element that promotes deoxidation of the molten metal during arc welding (a deoxidizing element) and is advantageous for suppressing the generation of blowholes. However, when the content of the above Zr exceeds 0.10%, there is a drawback that the electrocoating property of the welded part deteriorates. Therefore, the content of the above Zr is set to 0.10% or less. In addition, the welding wire of the present invention can selectively further contain B: 0.01% or less.

[0030] B: 0.01% or less The above B is an element that can enhance the hardening ability and improve the strength of the weld metal. However, when the content of the above B exceeds 0.01%, there is a drawback that the toughness of the weld metal may decrease in some cases due to excessive hardening ability. Therefore, the content of the above B is set to 0.01% or less.

[0031] In addition, the remaining components of the present invention are iron (Fe). However, in the normal manufacturing process, it is inevitable that unintended impurities may be mixed in from the raw materials or the surrounding environment, so this cannot be excluded. Since the above impurities are understandable to any ordinary technician, all the details thereof are not particularly mentioned in the present invention.

[0032] On the one hand, the welding wire of the present invention contains Mn and Si so as to satisfy the following relational expression 1. By satisfying the following relational expression 1, the strength and porosity resistance of the above-described weld metal can be improved. If the value defined by the above relational expression 1 is less than 2.0, the deoxidation effect of the weld metal may be insufficient, and problems such as insufficient strength due to a decrease in porosity resistance may occur. If it exceeds 5.2, not only does the viscosity of the weld metal increase, but also the zinc vapor pressure during welding increases according to the above-described principle, and the strength may be insufficient due to arc instability and a decrease in porosity resistance. Along with this, there may be a problem that the electrodeposition coating property deteriorates due to an increase in Si-based non-conductive oxides. [Relational Expression 1] 2.0 ≦ [Si] × 100 / [Mn] ≦ 5.2 (In the above relational expression 1, [Si] and [Mn] represent the weight % content of each element in parentheses with respect to the welding wire.)

[0033] In addition, the welding wire of the present invention is required to contain Ti and Al so as to satisfy the following relational expression 2. When welding a galvanized steel sheet, pore defects occur in the welded part due to the generation of zinc vapor. At this time, if the content of Si, which is a deoxidizer in the wire component, is lowered below a certain level, the viscosity of the molten metal becomes low, and the discharge of zinc vapor becomes smooth. As O generated by the dissociation of CO2 in the shielding gas at the high temperature during welding reacts more actively with Zn in the plating layer to form a Zn-based oxide, the zinc vapor pressure can be effectively reduced, the arc can be stabilized, and the occurrence of pore defects can be suppressed. However, when Ti or Al, which is a steel deoxidizer in the wire component, is contained in a content of a certain level or more, the above oxidation reaction of Zn is hindered, and arc instability, an increase in pore defects, and a decrease in the strength of the welded part are caused even with a low Si content. In particular, when the Ti + Al value is 0.10% or more, the increase in pore defects is obvious, and it is impossible to ensure a weld metal having excellent welded part strength and porosity resistance. [Relational Expression 2] [Ti] + [Al] < 0.10 (In the above relational expression 2, [Ti] and [Al] represent the weight % content of each element in parentheses with respect to the welding wire.)

[0034] On the one hand, in the present invention, the welding wire can be a solid wire, a metal-cored wire or a flux-cored wire, and is not limited to a specific wire type. Further, the present invention is a weld metal obtained by welding a weld base material using the welding wire of the present invention having the above-described composition components, and in the weld metal, the length fraction occupied by pore defects can satisfy 10% or less (including 0%) with respect to the total length of the weld metal. At this time, in the present invention, the weld base material is a hot-dip galvanized steel sheet having a hot-dip galvanized layer formed on its surface, the thickness of the hot-dip galvanized layer is 2 to 20 μm, and the one-sided plating amount is 5 to 120 g / m 2 is preferably.

[0035] Also, in the present invention, the composition components of the weld base material are not limited. As an example, the weld base material can consist of, by weight%, C: 0.04 to 0.18%, Si: 2.0% or less (including 0%), Mn: 0.5 to 3.0%, Cr: 2.0% or less (including 0%), Mo: 2.0% or less (including 0%), Al: 0.01 to 0.1%, P: 0.05% or less (excluding 0%), S: 0.05% or less (excluding 0%), and the balance being Fe and other inevitable impurities. The weld base material can selectively further contain one or more of Ti: 0.2% or less, Nb: 0.1% or less, and Cu: 0.1% or less. Furthermore, the weld base material preferably has a thickness of 0.8 to 4.0 mm.

[0036] On the one hand, in the present invention, the type of shielding gas used for welding the base metal is not particularly limited, and 100% CO2 gas, Ar + 20% CO2 gas, Ar + 10% CO2 gas, Ar + 5% CO2 gas, Ar + 2% O2 gas, etc. can be used as the shielding gas. In particular, when Ar + 5 - 20% CO2 is used as the shielding gas, the remarkable effects of the present invention can be exerted. That is, in the present invention, in order to ensure the tensile strength of the welded part without causing fracture of the weld metal or the fusion line, it is preferable to mix 5 - 20% of CO2 with Ar and use it as the protective gas during the welding.

[0037] Hereinafter, the present invention will be described more specifically with reference to examples. However, it should be noted that the following examples are merely for exemplifying and embodying the present invention, and are not intended to limit the scope of rights of the present invention. This is because the scope of rights of the present invention is determined by the matters described in the claims and those reasonably inferred therefrom.

Examples

[0038] Two base materials of hot-dip galvanized steel sheets with a tensile strength of 540 MPa, having the alloy composition shown in Table 1 below, a thickness of 2.0 mm, a length of 200 mm, a width of 150 mm, and a one-sided plating amount of 85 g / m 2 were prepared. And solid wires for gas shielded arc welding having the alloy composition described in Table 2 below were prepared.

[0039] Next, the above hot-dip galvanized steel sheets were lap joint welded using each of the solid wires for welding provided as described above. At this time, Pulse DC (shielding gas: Ar + 10 - 20% CO2) was used as the welding method, the shielding gas flow rate was 20 l / min, the angle of the welding torch was 45° with respect to the vertical direction of the base material, the wire protruding length was 15 mm, and the welding current / voltage / speed conditions were 200 A - 20 V - 80 cm / min. The gap of the lap joint was 0 mm and the length of the lap joint was 10 mm. On one side, welding was started at a position 10 mm from the starting point in the length direction of the welded base material. After welding was carried out for a length of 180 mm, welding was terminated at a position 10 mm from the end point on the side opposite to the welding start position.

[0040] For each welded part formed by the above welding, the porosity was measured, and the results are shown in Table 3 below. At this time, the specific method for measuring the porosity is as follows. The welded test pieces fabricated above were irradiated with X-rays to measure the respective pore lengths distributed in the welded parts. The porosity of the welded parts was calculated by dividing the total value obtained by summing up all these lengths by the total length of the welded parts. At this time, the sections 10 mm from the starting point and the end point of the welded parts were excluded from the measurement, and the porosity was taken as the average value of the measured values of three welded test pieces.

[0041] In addition, a tensile test was conducted on the welded parts formed above, and the position where fracture occurred was observed visually. At this time, if the fracture occurred in the welded base material or the heat affected zone, it was evaluated as qualified (O), and if the fracture occurred in the weld metal, it was evaluated as unqualified (×). And the specific method of the tensile test at this time is as follows. Tensile test pieces with a width of 30 mm and a length of 250 mm were processed from each of the welded test pieces fabricated above. After a uniaxial tensile test was carried out at a speed of 10 mm / min, the fracture position was investigated. At this time, the results of the tensile test were evaluated by using three welded test pieces to verify the reproducibility.

[0042]

Table 1

[0043]

Table 2

[0044]

Table 3

[0045] As shown in Tables 1 to 3 above, in the case of Invention Examples 1 to 5 that satisfy both the alloy components of the wire and Relational Expressions 1 to 2, the length fraction occupied by the porosity defects with respect to the total length of the weld metal is all 10% or less (including 0%), and furthermore, it can be seen that the fracture position of the welded part is also excellent as the base metal of the weld or the heat affected zone.

[0046] On the other hand, Comparative Examples 1 and 4 to 5 are cases where Relational Expressions 1 to 2 are outside the scope of the present invention, and show a high porosity of the welded part with any of the shielding gases or show a high porosity of the welded part with all of the shielding gases. As a result, it can be confirmed that the fracture position of the welded part also occurs in the weld metal. In addition, since Comparative Examples 2 to 3 and Comparative Examples 9 to 10 do not satisfy Relational Expression 2, they show a high porosity of the welded part with any of the shielding gases or show a high porosity of the welded part with all of the shielding gases. As a result, the fracture position of the welded part also occurred in the weld metal.

[0047] And Comparative Examples 6 to 8 are cases where Relational Expression 1 is not satisfied, and show a high porosity of the welded part with all of the shielding gases. As a result, it can be confirmed that the fracture position of the welded part also occurs in the weld metal. On the other hand, FIG. 1 is a photograph showing the appearance of a weld bead and the results of X-ray analysis during the formation of a weld metal using the welding wire of Invention Example 1 in an embodiment of the present invention, and FIG. 2 is a photograph showing the appearance of a weld bead and the results of X-ray analysis during the formation of a weld metal using the welding wire of Comparative Example 2 in an embodiment of the present invention.

Claims

1. By weight, C: 0.001 to 0.30%, Si: 0.25% or less (excluding 0%), Mn: 0.50 to 3.00%, P: 0.030% or less (excluding 0%), S: 0.030% or less (excluding 0%), Cr: 0.50% or less (excluding 0%), Mo: 0.60% or less (excluding 0%), Al: less than 0.10% (excluding 0%), Ni: 0.40% or less (excluding 0%), Cu: 0.50% or less (excluding 0%), Ti: less than 0.10% (excluding 0%), the balance being Fe and other inevitable impurities, and satisfying the following relational expressions 1 and 2. A wire for gas shielded arc welding characterized by this. [Relational Expression 1] 2.0 ≦ [Si] × 100 / [Mn] ≦ 5.2 [Relational Expression 2] [Ti] + [Al] < 0.10 (In the above relational expressions 1 and 2, [Si], [Mn], [Ti], and [Al] represent the weight% content of each element in parentheses with respect to the welding wire.)

2. The welding wire according to claim 1, characterized in that it contains Si in the range of 0.05 to 0.09%.

3. The welding wire according to claim 1, characterized in that it further contains one or more of Nb: 0.10% or less, V: 0.10% or less, and Zr: 0.10% or less.

4. The welding wire according to claim 1, characterized in that it further contains B: 0.01% or less.

5. The welding wire according to claim 1, characterized in that it is a solid wire, a metal cored wire or a flux cored wire.

6. A weld metal obtained by welding a weld base material using the welding wire according to claim 1, wherein the weld metal satisfies that the length fraction occupied by pore defects is 10% or less (including 0%) with respect to the total length of the weld metal. A weld metal characterized by this.

7. The weld metal according to claim 6, characterized in that the weld base material is a hot dip galvanized steel sheet having a hot dip galvanized layer formed on its surface.

8. The base metal for welding, by weight percentage, comprises C: 0.04 to 0.18%, Si: 2.0% or less (including 0%), Mn: 0.5 to 3.0%, Cr: 2.0% or less (including 0%), Mo: 2.0% or less (including 0%), Al: 0.01 to 0.1%, P: 0.05% or less (excluding 0%), S: 0.05% or less (excluding 0%), and the balance consists of Fe and other inevitable impurities, and is characterized in that it is the weld metal according to claim 6.

9. The base metal for welding further comprises one or more of Ti: 0.20% or less, Nb: 0.10% or less, and Cu: 0.10% or less, and is characterized in that it is the weld metal according to claim 8.

10. The base metal for welding has a thickness of 0.8 to 4.0 mm, and is characterized in that it is the weld metal according to claim 6.

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