Welding wire, welding method, and weld metal manufacturing method

Abstract

To provide a welding wire capable of improving electrodeposition coating properties and achieving both a lack resistance of an electrodeposition coating part and pore defect resistance after the electrodeposition coating.SOLUTION: A welding wire contains, for the total mass of the welding wire, C: 0.010-0.100 mass%, Si: 0.15-0.50 mass%, Mn: 1.70-3.00 mass%, Ti: 0.01-0.17 mass%, Al: 0.10 mass% or less (including 0 mass%), Cr: 1.00 mass% or less (including 0 mass%), Mo: 0.50 mass% or less (including 0 mass%), P: 0.030 mass% or less (including 0 mass%), S: 0.0300 mass% or less (including 0 mass%), Cu: 0.50 mass% or less (including 0 mass%), O: 0.0100 mass% or less (including 0 mass%), N: 0.0100 mass% or less (including 0 mass%), and the balance being Fe and inevitable impurities.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a welding wire used in gas-shielded arc welding, a welding method using the welding wire, and a method for producing a weld metal using the welding wire. [Background technology]

[0002] Automotive suspension parts are exposed to moisture from the road surface, so technology to prevent rusting of suspension parts is required. Generally, when manufacturing parts, the parts are arc-welded and then electro-deposition-coated to form an anti-rust coating on the surface, thereby preventing rusting of the suspension parts. However, after welding, welding slag (hereinafter simply referred to as "slag"), which has low electrical conductivity, is generated on the bead surface, and depending on the condition of the slag, it can inhibit the formation of the anti-rust coating (hereinafter simply referred to as "coating" or "electro-deposition coating").

[0003] Generally, the following methods are used: after welding, the slag remaining on the bead surface is mechanically removed, followed by electrodeposition coating; or, alternatively, electrodeposition coating is performed while the slag remains on the bead surface. If electrodeposition coating is performed while the slag remains on the bead surface, it becomes difficult to form a sufficient coating film, resulting in variations in the quality of the rust prevention properties of the finished parts. Furthermore, removing the slag mechanically increases the burden on the worker. Therefore, from the perspectives of quality and workload, it is preferable to minimize the amount of slag generated during arc welding.

[0004] As mentioned above, electrodeposition paintability is an extremely important performance factor that affects the quality and workload of welding automotive parts. Therefore, as an arc welding method that can improve electrodeposition paintability, a welding method using an 80% Ar-20% CO2 mixed gas is mainly used because it generates very little slag.

[0005] Furthermore, various wires have been developed that have improved electrodeposition coatability by adjusting the composition of specific components in the wire. For example, Patent Document 1 discloses a solid wire in which the contents of C, Si, Mn, Ti, Al, Sn, P, S, B, Cr, Ni, Mo, Nb, V, Cu, etc. in the wire are controlled, and the values ​​obtained by a formula using the contents of specific elements are controlled. Furthermore, Patent Document 2 discloses an ultra-low silicon welding wire in which the contents of C, Si, Mn, P, and S in the wire are controlled. Here, ultra-low silicon welding wire refers to a wire with an Si content of 0.1 mass% or less. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-3717 [Patent Document 2] Japanese Patent Application Publication No. 2019-81195 Summary of the Invention [Problem to be solved by the invention]

[0007] Recently, there has been a growing demand for the use of carbon dioxide gas or for an increased CO2 gas content in mixed gases in order to achieve higher welding speeds and reduce the cost of shielding gases. However, shielding gases are not only used for the purpose of blocking the atmosphere; the type of shielding gas also significantly affects the arc condition, various properties of the weld metal, and the properties and amount of slag produced. For this reason, if a shielding gas with a CO2 gas content exceeding 20% ​​is used in welding using the solid wire described in Patent Document 1, or if the CO2 gas content is increased in welding using the ultra-low silicon welding wire described in Patent Document 2, the desired "resistance to porosity defects" and "various performance characteristics against electrodeposition coating" may not be achieved.

[0008] Specifically, in a strong oxidizing atmosphere, such as one in which the CO2 gas content in the shielding gas exceeds 20%, the amount of slag increases and changes. Furthermore, if the wire contains a small amount of deoxidizing elements, deoxidation is insufficient during welding, making porosity defects more likely to occur. Here, porosity refers to pits or blowholes. Furthermore, if electrodeposition coating is performed after welding using conventional wires while leaving slag on the bead, even if electrodeposition coating is possible, the slag may become thick in some areas or the slag shape may cause the paint film to become unstable. As a result, for example, when conventional wires are used to weld automotive suspension parts, the slag is prone to peeling off after electrodeposition coating due to vibrations and impacts on the electrodeposition coating, resulting in the entire paint coating being removed and reducing rust prevention properties. In this specification, the ability of the paint film to resist chipping after electrodeposition coating is referred to as "electrodeposition coating chipping resistance."

[0009] The present invention has been made in view of the above-mentioned problems, and has an object to provide a welding wire that can improve electrodeposition coatability even when a carbon dioxide gas or a mixed gas having a mixing ratio of CO2 gas exceeding 20% ​​is used as a shielding gas, and can achieve both resistance to electrodeposition coating chipping and resistance to porosity defects after electrodeposition coating, a welding method using the welding wire, and a method for producing weld metal using the welding wire. [Means for solving the problem]

[0010] The above object of the present invention is achieved by the following configuration [1] relating to a welding wire.

[0011] [1] Based on the total mass of the welding wire, C: 0.010 mass% or more and 0.100 mass% or less, Si: 0.15% by mass or more and 0.50% by mass or less, Mn: 1.70 mass% or more and 3.00 mass% or less, Ti: 0.01% by mass or more and 0.17% by mass or less, Al: 0.10 mass% or less (including 0 mass%), Cr: 1.00% by mass or less (including 0% by mass), Mo: 0.50 mass% or less (including 0 mass%) P: 0.030% by mass or less (including 0% by mass), S: 0.0300 mass% or less (including 0 mass%), Cu: 0.50 mass% or less (including 0 mass%) O: 0.0100 mass% or less (including 0 mass%), N: 0.0100% by mass or less (including 0% by mass), A welding wire, the balance of which is Fe and unavoidable impurities.

[0012] Preferred embodiments of the present invention relating to the welding wire relate to the following [2] to [4].

[0013] [2] The Si content in the wire is expressed as mass% of the total mass of the wire [Si], The Ti content in the wire is expressed as mass% relative to the total mass of the wire [Ti], The Cr content in the wire is expressed as mass% relative to the total mass of the wire [Cr], The Mn content in the wire is expressed as mass% relative to the total mass of the wire [Mn], When the Mo content in the wire is expressed as [Mo] in mass% relative to the total mass of the wire, The welding wire according to [1], characterized in that the value F1 calculated by the following formula (1) is 55 or more. Formula (1): F1=200×(3.0×[Si]+0.3×[Ti]+5.0×[Cr]) / (1.2×[Mn]+1.8×[Mo])

[0014] [3] The O content in the wire is expressed as mass% of the total mass of the wire [O], The Si content in the wire is expressed as mass% relative to the total mass of the wire [Si], The Ti content in the wire is expressed as mass% relative to the total mass of the wire [Ti], The Cr content in the wire is expressed as mass% relative to the total mass of the wire [Cr], The Mn content in the wire is expressed as mass% relative to the total mass of the wire [Mn], The Mo content in the wire is expressed as mass% relative to the total mass of the wire [Mo], The Al content in the wire is expressed as mass% relative to the total mass of the wire [Al], The carbon content in the wire is expressed as mass% relative to the total mass of the wire [C], When expressed as The welding wire according to [1] or [2], characterized in that a value F2 calculated by the following formula (2) is 40.00 or less, and a value F3 calculated by the following formula (3) is 8.50 or less. Formula (2): F2=5×[C] / ([Cr]+5×[Mo]) Formula (3): F3=10000×[O] / (15×[Si]+3×[Mn]+12×[Ti]+20×[Al]+15×[Cr]+2×[Mo])

[0015] [4] S content in the wire in mass% of the total mass of the wire [S], The Si content in the wire is expressed as mass% relative to the total mass of the wire [Si], The Mn content in the wire is expressed as mass% relative to the total mass of the wire [Mn], The Ti content in the wire is expressed as mass% relative to the total mass of the wire [Ti], When the Al content in the wire is expressed as [Al] in mass% relative to the total mass of the wire, The welding wire according to any one of [1] to [3], wherein a value F4 calculated by the following formula (4) is 0.25 or more and 6.0 or less. Formula (4): F4=500×[S] / (5×[Si]+[Mn] / 10+[Ti]+[Al])

[0016] The above object of the present invention is achieved by the following configuration [5] relating to the welding method.

[0017] [5] A welding method, characterized by performing gas-shielded arc welding using the welding wire according to any one of [1] to [4].

[0018] A preferred embodiment of the present invention relating to a welding method relates to the following [6].

[0019] [6] The welding method according to [5], characterized in that the steel plate is gas-shielded arc-welded while alternately switching the feeding of the welding wire between a forward feeding period and a reverse feeding period.

[0020] The above object of the present invention is achieved by the following configuration [7] relating to a method for producing a weld metal.

[0021] [7] A method for producing a weld metal, characterized in that the welding wire according to any one of [1] to [4] is used to produce a weld metal by gas-shielded arc welding. [Effects of the Invention]

[0022] According to the present invention, it is possible to provide a welding wire that can improve electrodeposition coatability even when a mixed gas containing carbon dioxide gas or CO2 gas at a mixing ratio of more than 20% is used as a shielding gas, and that can achieve both resistance to electrodeposition coating chipping after electrodeposition coating and resistance to porosity defects, a welding method using the welding wire, and a method for producing weld metal using the welding wire. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present inventors have found that when a carbon dioxide or CO2 mixed gas mixture containing more than 20% carbon dioxide is used as a shielding gas, and electrodeposition coating is performed with slag remaining on the bead after welding, even if good electrodeposition coatability is achieved, the slag is prone to peeling off and chipping off the entire coating, depending on the state of the slag. Therefore, as a result of extensive research, the present inventors have found that by appropriately controlling the content of certain alloy components in the wire, not only electrodeposition coatability but also resistance to electrodeposition coating chipping and porosity defects can be improved. Furthermore, they have found that by controlling the value obtained by a specific formula using the contents of Si, Ti, Cr, Mn, and Mo in the wire, the shape of the slag can be appropriately adjusted, thereby improving resistance to electrodeposition coating chipping.

[0024] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. Note that the present invention is not limited to the embodiment described below, and can be carried out with any modifications within the scope of the gist of the present invention.

[0025] In this specification, the content of each component in the wire means mass % relative to the total mass of the welding wire unless otherwise specified, and the ratio of gas components in the shielding gas is expressed in volume %.

[0026] [Welding wire] The form of the welding wire according to this embodiment is not particularly limited as long as the content of each element in the wire is within the range of the present invention. For example, both solid wire and flux-cored wire for gas-shielded arc welding can be applied to the present invention, but solid wire is preferred. In this specification, these wires are collectively referred to as "welding wire" or "wire."

[0027] Hereinafter, the specific components in the wire and the reasons for limiting the numerical values ​​of their contents will be described in more detail.

[0028] <C: 0.010 mass% or more and 0.100 mass% or less> C is a component that has a deoxidizing effect and an effect of increasing the strength of the weld metal. In the welding of thin plates, since single-pass welding is applied, there is no risk of strength reduction due to reheat as in the case of multi-layer welding, and it is possible to obtain a strength equal to or higher than that of the base material. If the C content in the wire is less than 0.010 mass%, it becomes difficult to obtain the strength of mild steel that is minimally required. Therefore, the C content in the wire is 0.010 mass% or more with respect to the total mass of the wire, preferably 0.015 mass% or more, more preferably 0.020 mass% or more, and even more preferably 0.030 mass% or more. On the other hand, if the C content in the wire exceeds 0.100 mass%, not only does the deoxidizing effect become large, the arc becomes unstable, making it difficult to obtain sufficient shielding performance, but spatter and fume are likely to occur. Therefore, within the range where the desired strength of the weld metal can be ensured, it is preferable that the C content is less. Thus, the C content in the wire is 0.100 mass% or less with respect to the total mass of the wire, preferably 0.090 mass% or less, more preferably 0.080 mass% or less, and even more preferably 0.065 mass% or less.

[0029] <Si: 0.15 mass% or more and 0.50 mass% or less> Si is a component that has a deoxidizing effect and an effect of improving the bead conformity. Also, by appropriately controlling the Si content in the wire, it is possible to make the slag less likely to drip and make the bead shape at the weld termination smooth. If the Si content in the wire is less than 0.15% by mass, the deoxidation effect in the molten metal cannot be sufficiently obtained, and there is a risk that porosity defects will remain in the weld metal. Also, if the Si content in the wire is less than 0.15% by mass, spatter is likely to occur. Therefore, in this embodiment, by including Si in the wire at a predetermined content, the amount of spatter generated during welding can be reduced. Furthermore, if the Si content in the wire is 0.15% by mass or more, the viscosity of the molten slag increases, and the slag end alignment on the weld bead is improved, so the resistance to electrodeposition coating film peeling is improved. Therefore, the Si content in the wire is preferably 0.15% by mass or more, more preferably 0.17% by mass or more, still more preferably 0.19% by mass or more, and even more preferably 0.25% by mass or more with respect to the total mass of the wire. On the other hand, SiO2, which is an oxide of Si, is a non-conductive glassy oxide. When the Si content in the wire exceeds 0.50% by mass, it becomes an oxide and remains as slag on the weld bead, making it difficult to form a good electrodeposition coating film and deteriorating the electrodeposition coating property. Therefore, the Si content in the wire is preferably 0.50% by mass or less, more preferably 0.48% by mass or less, still more preferably 0.45% by mass or less, and even more preferably 0.40% by mass or less with respect to the total mass of the wire.

[0030] <Mn: 1.70% by mass or more and 3.00% by mass or less> Mn is an important component for ensuring the desired strength of the weld metal. In the wire according to this embodiment, in order to improve the welding workability, porosity defect resistance, and resistance to electrodeposition coating film peeling, the C content and Si content in the wire are limited to a predetermined range. Therefore, in order to obtain sufficient strength of the weld metal, it is necessary to appropriately control the Mn content. If the Mn content in the wire is less than 1.70% by mass, it becomes difficult to not only sufficiently obtain the strength of the weld metal but also obtain good porosity defect resistance. Therefore, the Mn content in the wire is 1.70% by mass or more, preferably 1.75% by mass or more, more preferably 1.80% by mass or more, and even more preferably 1.90% by mass or more based on the total mass of the wire. On the other hand, if the Mn content in the wire exceeds 3.00% by mass, excessive deoxidation progresses, the amount of oxygen in the molten pool decreases, and the viscosity and surface tension of the molten metal increase, so that a good bead shape cannot be obtained. In addition, due to the increase in the Mn content, the viscosity of the molten slag decreases and the slag is likely to drip, the slag termination alignment property on the weld bead deteriorates, and the resistance to electrodeposition coating part dropout deteriorates. Therefore, the Mn content in the wire is 3.00% by mass or less, preferably 2.50% by mass or less, more preferably 2.30% by mass or less, and even more preferably 2.00% by mass or less based on the total mass of the wire.

[0031] <Ti: 0.01% by mass or more and 0.17% by mass or less> Ti is a strong deoxidizing element and an element that preferentially forms oxides by its deoxidizing action. For this reason, like Mn and Si, Ti is an element that greatly contributes to the composition of the slag. In addition, by containing Ti in combination with Si in the wire, an effect of increasing the viscosity of the molten slag and making the slag less likely to drip can be obtained. If the Ti content in the wire is less than 0.01% by mass, a good slag shape cannot be obtained and the resistance to electrodeposition coating part dropout deteriorates. Therefore, the Ti content in the wire is 0.01% by mass or more, preferably 0.015% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.025% by mass or more based on the total mass of the wire. On the one hand, when the Ti content in the wire exceeds 0.17% by mass, excessive deoxidation proceeds, the amount of slag generated increases too much, and there is a risk of peeling off the slag due to the thickening of the slag, resulting in deterioration of the electrodeposition coating part loss resistance. Also, due to excessive progress of the deoxidation action, the bead shape deteriorates. Therefore, the Ti content in the wire should be 0.17% by mass or less, preferably 0.15% by mass or less, more preferably 0.13% by mass or less, and even more preferably 0.08% by mass or less, based on the total mass of the wire.

[0032] <Al: 0.10% by mass or less (including 0% by mass)> Al is an element having a strong deoxidation action and is an element that affects the yields of Si, Mn, and Ti in the weld metal. Also, Al is a strong deoxidizing element and has an effect of changing the physical properties of the slag. When the Al content in the wire exceeds 0.10% by mass, especially in a strong oxidation atmosphere where a mixed gas with a mixing ratio of carbon dioxide gas or CO2 gas exceeding 20% is used as the shielding gas, the amount of slag increases, thick slag is formed, and the electrodeposition coating part loss resistance deteriorates. Therefore, the Al content in the wire should be 0.10% by mass or less, preferably 0.09% by mass or less, more preferably 0.08% by mass or less, and even more preferably 0.07% by mass or less, based on the total mass of the wire. When Al is contained in the wire, the Al content in the wire is preferably 0.001% by mass or more, and more preferably 0.005% by mass or more, based on the total mass of the wire.

[0033] <Cr: 1.00% by mass or less (including 0% by mass)> By including Cr in the wire, an effect of enhancing the mechanical properties of the weld metal can be obtained. The Cr content in the wire can be appropriately adjusted according to the required strength of the weld metal. However, in this embodiment, if the strength can be ensured by other elements, the wire may not contain Cr, and it may be 0% by mass. Further, Cr has a deoxidizing action and is a component that not only improves the porosity defect resistance but also increases the viscosity of the molten slag to appropriately control the slag shape and further improves the resistance to falling-off of the electrocoating part. When Cr is included in the wire for the purpose of improving the mechanical properties or the resistance to falling-off of the electrocoating part of the weld metal, considering the balance with other elements for enhancing the mechanical properties in this embodiment, the Cr content in the wire is preferably 0.10% by mass or more, more preferably 0.15% by mass or more, and even more preferably 0.20% by mass or more with respect to the total mass of the wire. When the Cr content in the wire exceeds 1.00% by mass, in the multi-pass fillet welding of 440 - 980 MPa grade steel plates applied to the underbody parts of automobiles, the strength becomes excessive and it becomes difficult to form a weld metal with a suitable strength. Therefore, the Cr content in the wire is 1.00% by mass or less, preferably 0.70% by mass or less, more preferably 0.55% by mass or less, and even more preferably 0.40% by mass or less with respect to the total mass of the wire.

[0034] <Mo: 0.50% by mass or less (including 0% by mass)> By including Mo in the wire, the effect of enhancing the mechanical properties of the weld metal can be obtained. The Mo content in the wire can be appropriately adjusted according to the required strength of the weld metal. However, in this embodiment, if the strength can be ensured by other elements, the wire may not contain Mo, and it may be 0% by mass. When Mo is included in the wire for the purpose of improving the mechanical properties of the weld metal, considering the balance with other elements for enhancing other mechanical properties in this embodiment, the Mo content in the wire is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.10% by mass or more based on the total mass of the wire. When the Mo content in the wire exceeds 0.50% by mass, in the multi-pass fillet welding of 440 - 980 MPa grade steel plates applied to automotive underbody parts, the strength becomes excessive and it becomes difficult to form a weld metal with suitable strength. Also, when Mo is excessively contained in the wire, slag is likely to drip and sufficient resistance to electrodeposition coating film loss cannot be obtained. Therefore, the Mo content in the wire is 0.50% by mass or less, preferably 0.40% by mass or less, more preferably 0.35% by mass or less, and even more preferably 0.25% by mass or less based on the total mass of the wire.

[0035] <P: 0.030% by mass or less (including 0% by mass)> P is an element that reduces the crack resistance of the weld metal, and the lower the P content in the wire, the more preferable. When the P content in the wire exceeds 0.030% by mass, the required crack resistance cannot be obtained. Therefore, the P content in the wire is 0.030% by mass or less, preferably 0.025% by mass or less, and more preferably 0.020% by mass or less based on the total mass of the wire.

[0036] <S: 0.0300% by mass or less (including 0% by mass)> S is an element that has the effect of aggregating slag and affects the surface tension of the weld metal, thereby having the effect of improving the wettability of the weld bead and the bead shape. On the other hand, when the slag amount is fixed and the S content in the wire is changed, as the S content increases, the slag aggregates and thickens. From the perspective of electrodeposition coating property, the lower the S content in the wire, the more preferable. When the S content in the wire exceeds 0.0300% by mass, it becomes difficult to uniformly form a thin slag on the weld metal, and a good electrodeposition coating film cannot be formed, resulting in the inability to obtain the desired electrodeposition coating property, or the slag may peel off together, leading to a deterioration in the resistance to electrodeposition coating part dropout. Therefore, the S content in the wire is preferably 0.0300% by mass or less, more preferably 0.0250% by mass or less, still more preferably 0.0200% by mass or less, and even more preferably 0.0150% by mass or less with respect to the total mass of the wire. [[ID=X]] When S is contained in the wire, if the S content in the wire is 0.0010% by mass or more, the effect of improving the wettability of the weld bead and the bead shape can be obtained. Therefore, the S content in the wire is preferably 0.0010% by mass or more, more preferably 0.0030% by mass or more with respect to the total mass of the wire. [[ID=X]] [[ID=X]]

[0037] [[ID=X]] <Cu: 0.50% by mass or less (including 0% by mass)>[[ID=X]] By containing Cu in the wire, the effect of enhancing the mechanical properties of the weld metal can be obtained. Also, by applying a plating containing Cu on the surface of the wire, the electrical conductivity of the wire can be improved. When Cu is contained in the wire for the purpose of obtaining these effects, considering the balance with other elements in this embodiment, the Cu content in the wire is preferably 0.03% by mass or more, more preferably 0.05% by mass or more with respect to the total mass of the wire. [[ID=X]] It should be noted that in the above translation, for the tags like , etc., they are kept as they are because they are specific tags that need to be preserved exactly according to the requirements. Also, the placeholder <Cu: 0.50% by mass or less (including 0% by mass)> is translated as accurately as possible while maintaining its format. And the line breaks are maintained as in the original text.When the Cu content in the wire exceeds 0.50% by mass, in the fillet welding of steel sheets in the 440 to 980 MPa grade applied to automotive underbody parts, the strength becomes excessive and it becomes difficult to form a weld metal with suitable strength. Therefore, the Cu content in the wire should be 0.50% by mass or less based on the total mass of the wire, preferably 0.42% by mass or less, and more preferably 0.35% by mass or less. In addition, in this specification, the Cu content includes not only the Cu content contained in the bulk of the wire but also the Cu content in the plating formed on the wire surface.

[0038] <O: 0.0100% by mass or less (including 0% by mass)> O is not an essential component in the wire of this embodiment and is an element that affects the amount of slag generated and the porosity resistance. Therefore, it is preferable that the O content in the wire is low. When the O content in the wire exceeds 0.0100% by mass, it becomes impossible to obtain an appropriate amount of slag generation and excellent porosity resistance. Therefore, the O content in the wire should be 0.0100% by mass or less based on the total mass of the wire, preferably 0.0085% by mass or less, more preferably 0.0075% by mass or less, and even more preferably 0.0050% by mass or less. The lower limit value of the O content in the wire is not particularly defined, but for example, it is substantially 0.0005% by mass or more.

[0039] <N: 0.0100% by mass or less (including 0% by mass)> N is an element that has the effect of improving the strength and fatigue resistance of the weld metal, and the porosity resistance is improved by suppressing the N content to a certain content or less. When N is contained in the wire for the purpose of obtaining these effects, considering the balance with other elements in this embodiment, the N content in the wire is preferably 0.0035% by mass or more, and more preferably 0.0050% by mass or more based on the total mass of the wire.< If the N content in the wire exceeds 0.0100% by mass, not only will it be impossible to obtain excellent resistance to porosity defects, but spatter will increase and the bead shape will deteriorate. Therefore, the N content in the wire is set to 0.0100% by mass or less, preferably 0.0090% by mass or less, more preferably 0.0085% by mass or less, and even more preferably 0.0080% by mass or less, based on the total mass of the wire. There is no particular lower limit for the N content in the wire, but it is practically, for example, to be 0.0005% by mass or more.

[0040] In this embodiment, by specifying the content of the above-mentioned specific elements in the wire, it is possible to improve electrodeposition coatability and to achieve both resistance to electrodeposition coating chipping after electrodeposition coating and resistance to pore defects. Furthermore, by controlling the value calculated by the following formula using the content of the above-mentioned specific elements, it is possible to further improve the above-mentioned effects.

[0041] The following describes the preferred range of the value calculated by a predetermined formula using the content of each component contained in the wire and the reasons for limiting the numerical value. In the following formulas (1) to (6), [Si] is the Si content in the wire expressed as mass% relative to the total mass of the wire, [Ti] is the Ti content in the wire expressed as mass% with respect to the total mass of the wire, [Cr] is the Cr content in the wire expressed as mass% with respect to the total mass of the wire, [Mn] is the Mn content in the wire expressed as mass% with respect to the total mass of the wire, [Mo] is the value of the Mo content in the wire expressed as mass% with respect to the total mass of the wire, [O] is the value of the O content in the wire expressed as mass% with respect to the total mass of the wire, [Al] is the Al content in the wire expressed as mass% with respect to the total mass of the wire, [C] is the C content in the wire expressed as mass% with respect to the total mass of the wire, [S] is the value of the S content in the wire expressed as mass % relative to the total mass of the wire.

[0042] <Value F1 calculated by formula (1): 55 or more> By adjusting the ratio of the Si, Ti, Cr, Mn, and Mo contents in the wire, the viscosity of the slag can be appropriately controlled, which makes the slag less likely to drip and more effectively prevents the slag from becoming excessively thick and peeling off the electrodeposition coating. That is, by setting the value F1 calculated by the following formula (1) to 55 or more, the electrodeposition coating chipping resistance can be further improved. Therefore, the value F1 calculated by the following formula (1) is preferably 55 or more, more preferably 78 or more, and even more preferably 150 or more. Furthermore, while there is no particular upper limit, from the viewpoint of welding workability, the value F1 is preferably 400 or less, more preferably 350 or less, and even more preferably 300 or less. Formula (1): F1=200×(3.0×[Si]+0.3×[Ti]+5.0×[Cr]) / (1.2×[Mn]+1.8×[Mo])

[0043] Furthermore, the inventors of the present application have found that resistance to blowhole defects can be further improved by controlling the values ​​calculated by the following formulas (2) and (3) within appropriate ranges. Factors that cause blowhole defects in weld metal include the following. (A) Caused by zinc contained in the coating of galvanized steel sheets (B) Oxygen contained in molten metal Regarding (A), the zinc contained in the coating of the galvanized steel sheet itself may become trapped in the weld metal as bubbles, or the vaporization of zinc may cause the arc to become unstable, inhibiting the shielding gas and allowing nitrogen to enter the molten metal, resulting in the generation of blowhole defects. Therefore, the present inventors considered that, in order to further improve blowhole defect resistance, the intrusion of zinc vapor into the weld metal could be suppressed by ensuring arc stability, while increasing the viscosity of the molten metal to suppress the inflow of molten metal directly below the arc, thereby suppressing the intrusion of zinc vapor into the weld metal. Furthermore, the inventors of the present application have considered that, with regard to (B), by appropriately controlling the alloy elements contained in the wire, it is possible to promote deoxidation of the molten metal and further improve resistance to pore defects. Details are explained below.

[0044] <Value F2 calculated by formula (2): 40.00 or less> By appropriately controlling the C content in the wire, arc stability can be improved. However, excessive C content in the wire can cause spattering and other issues, making the arc unstable and more likely to entrain zinc vapor. Furthermore, by appropriately controlling the Cr and Mo content in the wire, the viscosity of the molten metal can be increased, suppressing the inflow of molten metal directly below the arc. This makes it easier to discharge zinc vapor directly below the arc, thereby suppressing the intrusion of zinc vapor into the molten metal. Specifically, by setting the value F2 calculated by the following formula (2) to 40.00 or less, the resistance to blowhole defects can be further improved. Therefore, the value F2 calculated by the following formula (2) is preferably 40.00 or less, more preferably 18.00 or less, and even more preferably 5.00 or less. Furthermore, although the lower limit is not particularly limited, from the viewpoint of welding workability, the value F2 is preferably 0.15 or more, more preferably 0.30 or more, and even more preferably 0.50 or more. Formula (2): F2=5×[C] / ([Cr]+5×[Mo])

[0045] <Value F3 calculated by formula (3): 8.50 or less> By appropriately controlling the content of each alloy element relative to the oxygen content in the wire, it is possible to suppress the incorporation of oxygen from the wire into the molten metal, promote deoxidation of the molten metal, and further suppress porosity defects. That is, by setting the value F3 calculated by the following formula (3) to 8.50 or less, it is possible to further improve porosity defect resistance. Therefore, the value F3 calculated by the following formula (3) is preferably set to 8.50 or less, more preferably set to 5.10 or less, and even more preferably set to 4.20 or less. Furthermore, although there is no particular restriction on the lower limit, from the viewpoint of welding workability, the value F3 is preferably set to 0.30 or more, more preferably set to 0.50 or more, and even more preferably set to 1.00 or more. Formula (3): F3=10000×[O] / (15×[Si]+3×[Mn]+12×[Ti]+20×[Al]+15×[Cr]+2×[Mo])

[0046] In the wire according to this embodiment, it is further preferable that the values ​​F4 to F6 calculated by the following formulas (4) to (6) based on the contents of S, Si, Mn, Ti, and Al are adjusted to fall within respective preferred ranges. The preferred ranges of the values ​​F4 to F6 and the reasons for limiting the numerical values ​​thereof will be explained below.

[0047] <Value F4 calculated by formula (4): 0.25 or more and 6.0 or less> When the value F4 calculated by the following formula (4) is 0.25 or more, the surface tension of the molten metal is prevented from becoming too large, and a stable bead shape can be obtained. Therefore, the value F4 calculated by the formula (4) is preferably 0.25 or more, more preferably 0.35 or more, and even more preferably 0.50 or more. On the other hand, if the value F4 calculated by the following formula (4) is 6.0 or less, not only is the deoxidizing effect improved and the resistance to pore defects further improved, but the aggregation of excess slag is suppressed, which prevents the slag from peeling off and further improves the resistance to electrodeposition coating chipping. Therefore, the value F4 calculated by the following formula (4) is preferably 6.0 or less, more preferably 4.5 or less, and even more preferably 3.0 or less. Formula (4): F4=500×[S] / (5×[Si]+[Mn] / 10+[Ti]+[Al])

[0048] <Value F5 calculated by formula (5): 0.85 or less> When combined with Ti, Al disperses the slag appropriately, preventing it from becoming excessively thick. Si is also an element that is effective in aligning the slag toes. By appropriately adjusting the ratio of the Ti and Al contents to the Si content in the wire, the amount of slag generated can be controlled, further preventing the electrodeposition coating from peeling off along with the slag. In other words, setting the value calculated by the following formula (5) to 0.85 or less can further improve the resistance to electrodeposition coating chipping. Therefore, the value F5 calculated by the following formula (5) is preferably 0.85 or less, and more preferably 0.65 or less. While the lower limit is not particularly limited, it is preferably 0.02 or more, and more preferably 0.08 or more, from the viewpoint of welding workability. Formula (5): F5=([Ti]+1.5×[Al]) / [Si]

[0049] <Value F6 calculated by formula (6): 15 or more and 105 or less> By appropriately adjusting the ratio of Mn content to Ti content in the wire, it is possible to control the amount of slag generated and further prevent the electrodeposition coating from peeling off together with the slag. In other words, by setting the value F6 calculated by the following formula (6) to 15 or more, it is possible to further improve the resistance to electrodeposition coating chipping. Therefore, the value F6 calculated by the following formula (6) is preferably 15 or more, and more preferably 20 or more. On the one hand, when the value F6 calculated by the following formula (6) is 105 or less, it is possible to prevent the viscosity of the molten slag from becoming too low, obtain better slag end alignment, and further improve the resistance to electrodeposition coating peeling. Therefore, the value F5 calculated by the following formula (6) is preferably 105 or less, more preferably 80 or less, and even more preferably 50 or less. Formula (6): F6 = [Mn] / [Ti]

[0050] The welding wire according to this embodiment defines the contents of C, Si, Mn, Ti, Al, Cr, Mo, P, S, Cu, O, and N in the wire, and preferably defines the values calculated by the above formulas (1) to (6). However, the welding wire may contain Ni or B within a range of a predetermined content or less. The upper limit values and reasons for limitation of the contents of Ni and B will be described below.

[0051] <Ni: 0.50 mass% or less (including 0 mass%)> Ni is not an essential component in the wire of this embodiment, but can be contained in the wire for the purpose of improving the strength of the weld metal. The content of Ni can be appropriately adjusted according to the required strength within a range not exceeding the specified upper limit value. In the case of lap fillet welding of 440 - 980 MPa grade steel plates applied to automotive underbody parts, when using the welding wire according to this embodiment and containing Ni in the wire, the Ni content is preferably 0.50 mass% or less, more preferably 0.40 mass% or less, based on the total mass of the wire. By suppressing the Ni content in the wire as described above, a balance can be achieved with other elements that enhance mechanical properties in this embodiment, and it is possible to prevent the weld metal from having excessive strength.

[0052] <B: 0.0100 mass% or less (including 0 mass%)> When the wire contains B, it is possible to obtain the effect of improving the mechanical properties of the weld metal. The B content can be adjusted appropriately depending on the required strength, as long as it does not exceed the specified upper limit. When the welding wire according to this embodiment is used for lap fillet welding of 440 to 980 MPa class steel sheets used in automobile suspension parts and B is contained in the wire, the B content is preferably 0.0100 mass% or less, and more preferably 0.0080 mass% or less, with respect to the total mass of the wire. By suppressing the B content in the wire as described above, a balance with the other elements in this embodiment that improve the mechanical properties can be achieved, and excessive strength of the weld metal can be suppressed.

[0053] <Balance: Fe and unavoidable impurities> The remainder of the wire components in this embodiment is Fe and unavoidable impurities. Examples of the unavoidable impurities include K, Na, Ca, Zr, Nb, V, Li, Bi, and As. The content of each of these unavoidable impurities is preferably 0.0500% by mass or less, more preferably 0.0100% by mass or less, and even more preferably 0.0080% by mass or less, based on the total mass of the wire. The total content of these unavoidable impurities is preferably 0.50% by mass or less, and even more preferably 0.10% by mass or less, based on the total mass of the wire.

[0054] (wire diameter) In this embodiment, the diameter of the welding wire is not particularly limited, but a wire having a diameter specified in welding material standards such as AWS or JIS can be used.

[0055] (Wire type) In this embodiment, the type of wire is not limited as long as the contents of C, Si, Mn, Ti, Al, Cr, Mo, P, S, Cu, O, and N in the wire are controlled within the specified ranges. However, in general, in the welding of automotive suspension parts, from the viewpoint of improving quality and work efficiency, welding materials that produce less welding slag and can reduce the slag removal work are required. Therefore, it is preferable that the oxide content in the wire is low. Therefore, a solid wire is preferred.

[0056] [Welding wire manufacturing method] The welding wire according to this embodiment is not particularly limited in its manufacturing method, and no special manufacturing conditions are required, and it can be manufactured by a conventional method. Specifically, in the case of a solid wire, first, a steel containing the above alloy elements in a specified content is melted to obtain an ingot. Next, the ingot is subjected to hot forging or the like as needed, followed by hot rolling and cold wire drawing to form a wire. Thereafter, the obtained wire is annealed at a temperature of about 500 to 900°C as needed, pickled, copper plated as needed, and further subjected to finish wire drawing as needed to obtain a target wire diameter. Thereafter, a lubricant is applied as needed, and the welding wire can be manufactured.

[0057] [Welding method] The welding method according to the present embodiment is a method of performing gas-shielded arc welding using the welding wire according to the present embodiment. Preferably, the welding method according to the present embodiment gas-shielded arc welding the steel plates while alternately switching the feeding of the welding wire between a forward feeding period and a reverse feeding period.

[0058] (shielding gas) In the welding method according to this embodiment, the shielding gas used is not particularly limited. From the viewpoint of shielding resistance, it is preferable to use a mixed gas containing, for example, more than 20% CO2 gas, more preferably 99.0% or more CO2 gas, even more preferably 99.5% or more CO2 gas, and even more preferably 99.8% or more CO2 gas. Carbon dioxide gas is particularly preferable. Carbon dioxide gas is composed of CO2 gas and impurities, and the impurities are preferably, for example, 0.5% or less, more preferably about 0.2%. When using a mixed gas, gases other than CO2 gas can be selected as appropriate, and specific examples include Ar gas and the like, which are readily available on the market.

[0059] (Welding conditions) In addition, in this embodiment, the steel material to be welded and the welding position are not particularly limited, but for example, when manufacturing automobile suspension parts, the welding wire according to this embodiment can be suitably used in lap fillet welding of 440 to 980 MPa class steel sheets. The welding conditions in this case are also not particularly limited, and general conditions used for welding using a wire can be applied.

[0060] (Feeding control method) The feed control method is a method of welding steel plates while alternately switching the feed of the welding wire between a forward feed period and a reverse feed period. The feed control method can be further classified into a "short-circuit type feed control method" and a "short-circuit suppression type feed control method." The short-circuit type feed control method is a type of welding based on a short-circuit transition mode in which the feed speed of the welding wire is alternately switched between a forward feed period and a reverse feed period, thereby generating a short-circuit period and an arc period. The short-circuit suppression type feed control method is a type of welding based on a globule transition mode in which the feed speed of the welding wire is alternately switched between a forward feed period and a reverse feed period, thereby suppressing the occurrence of a short-circuit period. The short-circuit suppression type feed control method has a pulse waveform in which the welding current alternates between a high-current period and a low-current period based on a phase related to the wire tip position (hereinafter referred to as the "wire position phase"). Here, the wire position phase is preferably within a range of 0 to 360°, with the forward feed period and the reverse feed period being one cycle, and with 0° being the closest to the tip side and 180° being the closest to the base metal side. In the welding method according to this embodiment, it is preferable to use a short-circuit suppression type feed control method, and it is more preferable to select the wire position phase at which the high current period ends from the range of 100 to 150° and the wire position phase at which the high current period starts from the range of 300 to 360°. By using the short-circuit suppression type feed control method and applying this condition, it is possible to obtain a weld bead with a better appearance and improve welding workability. It is also possible to suppress the occurrence of porosity defects.

[0061] [Weld metal manufacturing method] The method for producing a weld metal according to this embodiment is a method for producing a weld metal while supplying a shielding gas using the welding wire according to the embodiment. When using the method for producing a weld metal according to this embodiment, the welding method is not particularly limited except for using the welding wire according to this embodiment, but the welding method according to the embodiment can be used. [Example]

[0062] Hereinafter, examples of the welding wire according to the present embodiment and comparative examples will be described.

[0063] [Gas-shielded arc welding] (Welding wire production) Solid wires with a diameter of 1.2 mm were produced from ingots containing various alloying elements.

[0064] (gas shielded arc welding) Next, gas-shielded arc welding was carried out using the obtained welding wire while controlling the feeding of the welding wire. The welding conditions and the conditions for controlling the feeding are shown in Table 1 below.

[0065] [Table 1]

[0066] [Evaluation test] The welded joints obtained using the wires of the invention examples and the comparative examples were evaluated for resistance to electrodeposition coating chipping, electrodeposition coating properties, and resistance to pore defects.

[0067] (Resistance to electrodeposition coating chipping) The resistance to electrocoat chipping correlates with the shape of the slag in the weld. Specifically, when slag drips, the slag thickens in the area where it drips, making it more likely to peel off and resulting in poor resistance to electrocoat chipping. Therefore, the resistance to electrocoat chipping was evaluated by observing the shape of the slag in the weld. Specifically, the weld was observed from the front, and the difference (distance d) between the maximum and minimum distances from the vertical top end of the slag (the end on the upper plate side) to the bottom end was measured. The width of the weld metal in the vertical direction (weld width D) was also measured. The ratio (d / D) of the distance d to the weld width D was then calculated. In other words, a small ratio (d / D) indicates less slag dripping and better resistance to electrocoat chipping. The evaluation criteria for electrodeposition coating defect resistance were as follows: a ratio (d / D) of 0.35 or less was rated as ⊚ (best), a ratio of more than 0.35 but less than 0.53 was rated as ◯ (good), and a ratio of 0.53 or more was rated x (poor).

[0068] (Electrodeposition paintability) The electrodeposition paintability was evaluated by applying electrodeposition paint to the welded joint after welding and visually observing the surface of the bead. The evaluation criteria for electrodeposition paintability were that the entire bead was covered with electrodeposition paint, which was rated as ○ (good). Furthermore, the case where even a partial coating defect was observed was rated as × (bad).

[0069] (Porosity defect resistance) The resistance to porosity defects was evaluated in terms of pit resistance and blowhole resistance. Pit resistance was evaluated by visually observing the surface of the bead after welding using a galvanized steel sheet as the base material to confirm the presence or absence of pits. Blowhole resistance was evaluated by observing blowholes using a radiographic test. The evaluation criteria for pit resistance were as follows: when no pits occurred on the bead, it was evaluated as ○ (good); and when pits occurred on the bead, it was evaluated as × (poor). The evaluation criteria for blowhole resistance were as follows: when there were zero blowholes of 0.7 mm or more in the direction of the weld line and 0.7 mm or more in the direction perpendicular to the weld line, it was evaluated as ⊚ (best); when there were 1 to 3 blowholes of the above sizes, it was evaluated as ○ (good); and when there were 4 or more blowholes of the above sizes, it was evaluated as × (poor).

[0070] Furthermore, as the evaluation criteria for the overall evaluation of pore defect resistance, a sample that was x (poor) in at least one of the evaluation results for pit resistance or blowhole resistance was evaluated as x (poor). A sample that was o (good) in both pit resistance and blowhole resistance was evaluated as o (good), and a sample that was o (good) in pit resistance and ⊚ (best) in blowhole resistance was evaluated as ⊚ (best).

[0071] The contents of each component contained in the welding wire used are shown in Tables 2 and 3 below, and the values ​​F1 to F6 calculated using these contents according to formulas (1) to (6) are shown in Table 4 below. The results of each evaluation test are also shown in Table 5 below.

[0072] In Table 4 below, formulas (1) to (6) are as follows: Formula (1): F1=200×(3.0×[Si]+0.3×[Ti]+5.0×[Cr]) / (1.2×[Mn]+1.8×[Mo]) Formula (2): F2=5×[C] / ([Cr]+5×[Mo]) Formula (3): F3=10000×[O] / (15×[Si]+3×[Mn]+12×[Ti]+20×[Al]+15×[Cr]+2×[Mo]) Formula (4): F4=500×[S] / (5×[Si]+[Mn] / 10+[Ti]+[Al]) Formula (5): F5=([Ti]+1.5×[Al]) / [Si] Formula (6): F6=[Mn] / [Ti]

[0073] However, in the above formulas (1) to (6), [Si] is the Si content in the wire expressed as mass% relative to the total mass of the wire, [Ti] is the Ti content in the wire expressed as mass% with respect to the total mass of the wire, [Cr] is the Cr content in the wire expressed as mass% with respect to the total mass of the wire, [Mn] is the Mn content in the wire expressed as mass% with respect to the total mass of the wire, [Mo] is the value of the Mo content in the wire expressed as mass% with respect to the total mass of the wire, [O] is the value of the O content in the wire expressed as mass% with respect to the total mass of the wire, [Al] is the Al content in the wire expressed as mass% with respect to the total mass of the wire, [C] is the C content in the wire expressed as mass% with respect to the total mass of the wire, [S] is the value of the S content in the wire expressed as mass % relative to the total mass of the wire.

[0074] In addition, in the column for the content of each component in Table 2 below, "-" indicates that the component was not added or was below the detection limit. Furthermore, when the content of each element used in formulas (1) to (6) was "-", the content of that element was set to 0 (zero) to calculate F1 to F6.

[0075] [Table 2]

[0076] [Table 3]

[0077] [Table 4]

[0078] [Table 5]

[0079] As shown in Tables 2 to 5 above, Invention Examples Nos. 1 to 22, in which the content of each component in the welding wire was within the range specified by the present invention, were excellent in electrodeposition paintability, and were able to achieve both resistance to electrodeposition paint chipping and resistance to pore defects.

[0080] On the other hand, in Comparative Example No. 1, the Si content in the wire was less than the lower limit specified in the present invention, and the Ti content exceeded the upper limit specified in the present invention, so the resistance to electrodeposition coating chipping and pore defect resistance were poor.

[0081] In Comparative Example No. 2, the Si content and Mn content in the wire were less than the lower limit values ​​specified in the present invention, and the Ti content exceeded the upper limit specified in the present invention, so the resistance to electrodeposition coating chipping and resistance to pore defects were poor.

[0082] In Comparative Example No. 3, the Si content and Mn content in the wire were less than the lower limit values ​​specified in the present invention, and therefore the resistance to electrodeposition coating chipping and pore defects were poor.

[0083] In Comparative Example No. 4, the Si content in the wire was less than the lower limit specified in the present invention, and therefore the resistance to chipping of the electrodeposition coating was poor.

[0084] In Comparative Example No. 5, the Ti content in the wire was less than the lower limit specified in the present invention, and therefore the resistance to chipping of the electrodeposition coating was poor.

[0085] In Comparative Example No. 6, the Mo content in the wire exceeded the upper limit specified in the present invention, and therefore the resistance to chipping of the electrodeposition coating was poor.

Claims

1. For the total mass of welding wire, C: 0.010% by mass or more and 0.100% by mass or less, Si: 0.15% by mass or more and 0.50% by mass or less, Mn: 1.70% by mass or more and 3.00% by mass or less, Ti: 0.01% by mass or more and 0.17% by mass or less; Al: 0.10 mass% or less (including 0 mass%), Cr: 1.00% by mass or less (including 0% by mass), Mo: 0.50 mass% or less (including 0 mass%), P: 0.030% by mass or less (including 0% by mass), S: 0.0300% by mass or less (including 0% by mass), Cu: 0.50 mass% or less (including 0 mass%), O: 0.0100% by mass or less (including 0% by mass), N: 0.0100% by mass or less (including 0% by mass), A welding wire, the balance of which is Fe and unavoidable impurities.

2. The Si content in the wire is expressed as mass% [Si] relative to the total mass of the wire, The Ti content in the wire is expressed as [Ti] in mass% relative to the total mass of the wire, The Cr content in the wire is expressed as mass% relative to the total mass of the wire [Cr], The Mn content in the wire is expressed as mass% relative to the total mass of the wire [Mn], When the Mo content in the wire is expressed as [Mo] in mass% relative to the total mass of the wire, The welding wire according to claim 1, wherein a value F1 calculated by the following formula (1) is 55 or more: Formula (1): F1=200×(3.0×[Si]+0.3×[Ti]+5.0×[Cr]) / (1.2×[Mn]+1.8×[Mo])

3. The O content in the wire is expressed as [O] in mass% relative to the total mass of the wire, The Si content in the wire is expressed as mass% [Si] relative to the total mass of the wire, The Ti content in the wire is expressed as [Ti] in mass% relative to the total mass of the wire, The Cr content in the wire is expressed as mass% relative to the total mass of the wire [Cr], The Mn content in the wire is expressed as mass% relative to the total mass of the wire [Mn], The Mo content in the wire is expressed as [Mo] in mass% relative to the total mass of the wire, The Al content in the wire is expressed as mass% [Al] relative to the total mass of the wire, The C content in the wire is expressed as mass% relative to the total mass of the wire [C], When expressed as 2. The welding wire according to claim 1, wherein a value F2 calculated by the following formula (2) is 40.00 or less, and a value F3 calculated by the following formula (3) is 8.50 or less. Formula (2): F2=5×[C] / ([Cr]+5×[Mo]) Formula (3): F3=10000×[O] / (15×[Si]+3×[Mn]+12×[Ti]+20×[Al]+15×[Cr]+2×[Mo])

4. The S content in the wire is expressed as [S] in mass% relative to the total mass of the wire, The Si content in the wire is expressed as mass% [Si] relative to the total mass of the wire, The Mn content in the wire is expressed as mass% relative to the total mass of the wire [Mn], The Ti content in the wire is expressed as [Ti] in mass% relative to the total mass of the wire, When the Al content in the wire is expressed as [Al] in mass% relative to the total mass of the wire, The welding wire according to claim 1, wherein a value F4 calculated by the following formula (4) is 0.25 or more and 6.0 or less: Formula (4): F4=500×[S] / (5×[Si]+[Mn] / 10+[Ti]+[Al])

5. A welding method comprising gas-shielded arc welding using the welding wire according to any one of claims 1 to 4.

6. 6. The welding method according to claim 5, wherein the steel plates are gas-shielded arc-welded while alternately switching the feeding of the welding wire between a forward feeding period and a reverse feeding period.

7. A method for producing a weld metal, comprising producing the weld metal by gas-shielded arc welding using the welding wire according to any one of claims 1 to 4.

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