Solid wire for gas shielded arc welding and method for manufacturing welded joint

Abstract

A solid wire for gas shielded arc welding according to one aspect of the present disclosure contains C: 0.04-0.12%, Si: 0.13-0.28%, Mn: 1.4-2.3%, Ti: 0.13-0.25%, Al: 0.001-0.050%, and the like in mass% with respect to the total mass of the solid wire, and satisfies Si * Mn < = 0.60, (Si + Mn / 5) / (Ti + Al) < = 4.0, 1.00 < = Si + 0.5 * (Mn + Cr) + 0.3 * Ni, 0.30 < = C + Mn / 6 + Si / 24 + Ni / 40 + Cr / 5 + Mo / 4 + V / 14 < = 0.55, and 0 < = Cr + Ni < = 3.00.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a solid wire for gas shielded arc welding and a method for manufacturing a welded joint.

[0002] This application claims priority based on Japanese Patent Application No. 2023-141138 filed on August 31, 2023, and the content thereof is hereby incorporated by reference. BACKGROUND

[0003] Gas shielded arc welding is widely used in various fields. For example, in the automobile field, gas shielded arc welding is used for welding of walking members and the like. One example of a welding material in gas shielded arc welding is a solid wire. A solid wire is a welding wire in which flux is not present in the center portion or the like of the cross section of the welding wire, and the cross section becomes solid. Various solid wires for gas shielded arc welding have been proposed in the related art.

[0004] Patent Literature 1 discloses a welding wire for gas shielded arc welding, which contains, in the total mass of the welding wire per unit, C: 0.01 to 0.10 mass%, Si: 0.05 to 0.55 mass%, Mn: 1.60 to 2.40 mass%, Ti: 0.05 to 0.25 mass%, Cu: 0.30 mass% or less, Al: 0.10 mass% or less, P: 0.025 mass% or less, S: 0.010 mass% or less, and the remainder is Fe and inevitable impurities, and when the Si content (mass%) in the total mass of the welding wire per unit is set to [Si], and the Ti content (mass%) in the total mass of the welding wire per unit is set to [Ti], 0.1 ≤ [Ti] / [Si] ≤ 3.0.

[0005] Patent Literature 2 discloses an extremely low silicon welding wire for welding, which contains, in terms of mass%, C: 0.001 to 0.30%, Si: 0.15% or less, Mn: 0.50 to 3.00%, P: 0.030% or less, S: 0.030% or less, and the remainder is Fe and inevitable impurities.

[0006] Prior Art Documents

[0007] Patent Literature

[0008] Patent Literature 1: Japanese Patent Application Publication No. 2021-45761

[0009] Patent Literature 2: Japanese Patent Application Publication No. 2019-81195 SUMMARY

[0010] Problems to be Solved by the Invention

[0011] If gas shielded arc welding is performed using a solid core welding wire for a steel member, oxygen contained in the oxidizing gas in the shielding gas reacts with Si, Mn, etc. contained in the steel material and the welding wire to generate Si, Mn-based slag with Si oxide and Mn oxide as the main components. As a result, a large amount of Si, Mn-based slag remains on the surface of the bead as the molten solidified portion.

[0012] The slag adhering to the bead of the welded joint can impair the electrodeposition paintability of the welded joint. The reason why the electrodeposition paintability is reduced at the remaining portion of the slag is because Si oxide and Mn oxide, which are insulators, are not electrified at the time of electrodeposition painting, and the paint does not adhere to the entire surface of the welded portion.

[0013] Patent Document 1 and Patent Document 2 propose reducing the content of Si as a means for improving the electrodeposition paintability. Either document discloses that the slag formed by the combination of Si and oxygen in welding impairs the electrodeposition paintability of the welded joint.

[0014] However, the present inventors have found that a solid core welding wire in which Si is reduced impairs the welding workability. Specifically, a solid core welding wire in which Si is reduced increases spatter and impairs the plate gap weldability in lap welding.

[0015] Spatter is a molten metal particle that is scattered in arc welding. Spatter impairs the welding workability. In addition, a portion of the spatter scattered into the welding work environment adheres to the surface of the welded joint, impairing the appearance of the welded joint. In addition, the spatter adhering to the surface of the welded joint can also become a starting point of fatigue cracking and a starting point of red rust caused by poor electrodeposition painting. A process of removing the spatter adhering to the welded joint increases the manufacturing cost of the welded joint.

[0016] Plate gap weldability refers to the ability to form a normal joint portion when welding a plurality of steel plates that are overlapped. In actual welding construction, there are many cases where a gap is generated between the steel plates at the welded portion due to variations in pressing quality and assembly accuracy, etc. In a lap fillet joint, which is frequently used in arc welding of thin steel plates, if the gap between the steel plates increases, the shape of the welded portion connecting the upper plate and the lower plate becomes easily disordered. In a joint in which the welded portion is Figure 3B In a joint in which the welded portion is Figure 3B In a case where a plate set in which a plate gap S exists between the upper plate and the lower plate is welded, a solid core welding wire in which the welded metal 1 cannot be formed to the upper end of the upper plate end surface is evaluated as having low plate gap weldability. In a case where welding is performed using a solid core welding wire having low plate gap weldability, as shown in

[0017] On the other hand, as Figure 3A As shown in FIG. 1, in a case where a plate set in which a plate gap S exists between an upper plate and a lower plate is welded, the end surface of the upper plate is entirely melted, and a solid wire for which a weld 1 is formed to a corner portion of a weld portion (weld joint) of the upper plate is evaluated as having high plate gap weldability.

[0018] In a lap fillet arc welding using a solid wire in which Si is reduced in order to improve electrodeposition paintability, it is easy to form a weld portion having a shape as exemplified in FIG. 2. The same problem occurs in welding other than lap fillet welding. Figure 3B

[0019] In addition, if the amount of alloy elements contained in the solid wire increases, the hardness of the alloy constituting the solid wire increases. Due to this, the manufacturability of the solid wire is impaired. The solid wire is obtained by subjecting a wire rod to wire drawing. In order to increase the amount of alloy elements of the solid wire, the more the amount of alloy elements of the wire rod, the more difficult the wire drawing of the wire rod becomes.

[0020] A solid wire capable of solving all of the above problems is desired in the industry, but according to the related art, the request cannot be sufficiently met. The problem of Patent Literature 1 is to improve the spatter resistance of a solid wire and the electrodeposition paintability of a weld joint obtained using the solid wire. However, Patent Literature 1 does not make any study on the plate gap weldability and manufacturability of the solid wire. The problem of Patent Literature 2 is to improve the electrodeposition paintability of a weld joint obtained using a solid wire. However, Patent Literature 2 does not make any study on the spatter resistance, plate gap weldability, and manufacturability of the solid wire.

[0021] The problem of the present disclosure is to provide a gas shielded arc welding solid wire and a method for manufacturing a weld joint, which can avoid welding failure in a plate set having a large gap, further have excellent wire drawing workability at the time of wire manufacturing, and can manufacture a weld joint having high electrodeposition paintability.

[0022] Means for solving the problem

[0023] The gist of the present disclosure is as follows.

[0024] ​(1) The solid wire for gas shielded arc welding according to one aspect of the present disclosure has, in mass%, C: 0.04 to 0.12%, Si: 0.13 to 0.28%, Mn: 1.4 to 2.3%, Ti: 0.13 to 0.25%, Al: 0.001 to 0.050%, Cr: 0 to 3.00%, Ni: 0 to 3.00%, P: 0.020% or less, S: 0.015% or less, N: 0.0060% or less, Mo: 0 to 0.5%, B: 0 to 0.0100%, Cu: 0 to 0.50%, Nb: 0 to 0.30%, V: 0 to 0.5%, Zr: 0 to 0.20%, Mg: 0 to 0.050%, As: 0 to 0.020%, Sn: 0 to 0.100%, Sb: 0 to 0.10%, and the balance: iron and impurities, and satisfies the following (i) formula, (ii) formula, (iii) formula, (iv) formula, and (v) formula.

[0025] Si x Mn ≤ 0.60 (i) formula

[0026] (Si + Mn / 5) / (Ti + Al) ≤ 4.0 (ii) formula

[0027] 1.00 ≤ Si + 0.5 x (Mn + Cr) + 0.3 x Ni (iii) formula

[0028] 0.30 ≤ C + Mn / 6 + Si / 24 + Ni / 40 + Cr / 5 + Mo / 4 + V / 14 ≤ 0.55 (iv) formula

[0029] 0 ≤ Cr + Ni ≤ 3.00 (v) formula

[0030] wherein the element symbols in the (i) formula, the (ii) formula, the (iii) formula, the (iv) formula, and the (v) formula are contents of the respective elements in mass% with respect to the total mass of the solid wire.

[0031] (2) Preferably, the solid wire for gas shielded arc welding according to the above (1) satisfies 0.16 ≤ C x (5 x Si + Mn) ≤ 0.35 (vi) formula in mass% with respect to the total mass of the solid wire.

[0032] (3) Preferably, the solid wire for gas shielded arc welding according to the above (1) or (2) contains one or more selected from Al: 0.010 to 0.050%, Cr: 0.10 to 1.50%, Ni: 0.10 to 3.00%, and B: 0.0030 to 0.0100% in mass% with respect to the total mass of the solid wire.

[0033] (4) Preferably, the solid wire for gas shielded arc welding according to any one of the above (1) to (3) has a hardness measured in a cross section of the solid wire satisfying the following (vii) formula and (viii) formula.

[0034] H2≥ 250 (vii) formula

[0035] H2- H1≥ 40 (viii) formula

[0036] wherein the symbol H1 in the (viii) formula is a Vickers hardness measured at a position at a depth of 0.05 mm from a surface of the solid wire, and the symbol H2 in the (vii) formula and the (viii) formula is an average of Vickers hardnesses measured at positions at depths of 0.25 mm and 0.35 mm from the surface.

[0037] (5) Preferably, the solid wire for gas shielded arc welding according to any one of the above (1) to (4) has, in terms of mass %, Si: 0.13 to 0.19% relative to the total mass of the solid wire.

[0038] (6) Preferably, the solid wire for gas shielded arc welding according to any one of the above (1) to (5) has, in terms of mass %, Cr: 0.15 to 3.00% relative to the total mass of the solid wire.

[0039] (7) Preferably, the solid wire for gas shielded arc welding according to any one of the above (1) to (5) has, in terms of mass %, Cr: 0% or more and less than 0.50% relative to the total mass of the solid wire.

[0040] (8) Preferably, the solid wire for gas shielded arc welding according to any one of the above (1) to (7) has, in terms of mass %, Ni: 0 to 0.45% relative to the total mass of the solid wire.

[0041] (9) Preferably, the solid wire for gas shielded arc welding according to any one of the above (1) to (8) satisfies the following (ix) formula in terms of mass % relative to the total mass of the solid wire: 0.05 ≤ Cr + Ni ≤ 3.00.

[0042] (10) Preferably, the solid wire for gas shielded arc welding according to any one of the above (1) to (9) has a diameter of 0.8 to 1.4 mm.

[0043] (11) A method of manufacturing a welded joint according to another aspect of the present disclosure includes a step of performing gas shielded arc welding on a steel sheet using the solid wire for gas shielded arc welding according to any one of the above (1) to (10).

[0044] Inventive Effects

[0045] According to the present disclosure, it is possible to provide a solid wire for gas shielded arc welding and a method for manufacturing a welded joint, which can avoid poor welding in a large gap plate group, further have excellent wire drawing workability at the time of manufacturing the welding wire, and can manufacture a welded joint having high electrodeposition painting property. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is a graph showing experimental results obtained by investigating the relationship between Si + 0.5 x (Mn + Cr) + 0.3 x Ni and plate gap weldability.

[0047] Figure 2 is a graph showing experimental results obtained by investigating the relationship between C x (5 x Si + Mn) and spatter amount.

[0048] Figure 3A is one example of a cross-sectional view of a welded portion obtained using a solid wire having high plate gap weldability.

[0049] Figure 3B is one example of a cross-sectional view of a welded portion obtained using a solid wire having low plate gap weldability.

[0050] Figure 4 is a schematic view showing a gap between steel plates for evaluating plate gap weldability.

[0051] Figure 5A is a schematic view showing a transfer state of a droplet from a leading end of a solid wire having low droplet transfer characteristics.

[0052] Figure 5B is a schematic view showing a transfer state of a droplet from a leading end of a solid wire having high droplet transfer characteristics.

[0053] Figure 6 is a graph showing an example of cross-sectional hardness of various welding wires. DETAILED DESCRIPTION

[0054] First, the technical idea of the solid wire of the present embodiment will be described. Note that in the following description, a numerical range indicated by "to" means a range including the numerical values written before and after "to" as lower limit values and upper limit values, unless otherwise specified. However, in the case where "more than" or "less than" is indicated for the numerical values written before and after "to", the numerical range means a range not including these numerical values as lower limit values or upper limit values.

[0055] (1. Electrodeposition painting property)

[0056] The inventors of the present invention have intensively studied countermeasures for solving the electrodeposition paintability, and have obtained the following insights.

[0057] (A) The electrodeposition paintability is improved by suppressing the generation of Si-based dross by reducing the Si content of the solid wire as much as possible. In a composition system with little Si, the degree of deterioration of the electrodeposition paintability due to Mn dross is small.

[0058] (B) The electrodeposition paintability is improved by controlling the Ti content of the solid wire within an appropriate range, so that Ti-based dross having electrical conductivity is generated on the surface of the weld bead.

[0059] (C) The electrodeposition paintability is improved by controlling the Ti content and the Al content of the solid wire within an appropriate range, so that the generation of Si- and Mn-based dross having insulating properties is suppressed.

[0060] Based on the above insights, the inventors of the present invention have found the following (1) and (2) formulas.

[0061] Si x Mn ≤ 0.60 (1)

[0062] (Si + Mn / 5) / (Ti + Al) ≤ 4.0 (2)

[0063] By controlling the alloy composition of the solid wire in such a way as to satisfy the (1) and (2) formulas, the electrodeposition paintability of the welded joint can be improved.

[0064] On the other hand, according to the solid wire satisfying the above-mentioned requirements, the plate gap weldability deteriorates, and the spatter amount increases. Therefore, the inventors of the present invention have repeatedly studied countermeasures for improving the electrodeposition paintability while ensuring the plate gap weldability and spatter resistance.

[0065] (2. Plate gap weldability)

[0066] The inventors of the present invention prepared various lap fillet welded joints provided with a plate gap S, and observed the welded portions thereof. In the lap fillet welded joint shown in Figure 3A in which the plate gap weldability is good, the end surface of the upper steel sheet 2 is molten and solidified, and the weld metal 1 is formed up to the upper end of the end surface of the upper steel sheet 2, and is firmly bonded to the weld metal 1. On the other hand, in the lap fillet welded joint shown in Figure 3B in which the plate gap weldability is poor, it is considered that the end surface of the upper steel sheet 2 is not sufficiently molten and solidified, and the strength for joining the upper and lower steel sheets can be reduced.

[0067] The inventors of the present invention believe that the high-temperature physical values of the weld metal such as viscosity, surface tension caused by the composition of the molten metal, and the heat input balance for melting the welding wire together have an influence on the gap weldability. The inventors of the present invention focused on the heat input balance and investigated the influence of the resistance value of the solid wire on the heat input balance.

[0068] In gas shielded arc welding, the solid wire is melted, and the molten metal is transferred from the front end of the solid wire to the steel plate side. The heat for melting the solid wire is caused by the electric resistance heating of the current flowing in the solid wire and the arc plasma generated between the solid wire and the steel plate. If the Si content of the solid wire is reduced, the resistance value of the solid wire becomes smaller, and the electric resistance heating amount becomes smaller. Then, the solid wire becomes not sufficiently melted. If the welding current value is increased in order to secure the heat for melting the solid wire, the heat generated in the steel plate and the molten metal increases, and the molten metal is excessively heated. Thereby, it is believed that the burn-through of the welded portion is promoted.

[0069] Based on the above knowledge, the inventors of the present invention found the following (3) formula.

[0070] 1.00 ≤ Si + 0.5 x (Mn + Cr) + 0.3 x Ni (3) formula

[0071] "Si + 0.5 x (Mn + Cr) + 0.3 x Ni" contained in the (3) formula is an index of the resistance value of the solid wire. Mn, Cr, and Ni have the same effect as Si to increase the resistance value of the steel. By controlling the alloy composition of the solid wire in a manner to satisfy the (3) formula, the electric resistance heating and melting of the solid wire at the time of gas shielded arc welding are promoted, and the excessive heating of the molten metal is directed to be suppressed.

[0072] In Figure 1 The experimental results of the inventors of the present invention on the effect of the (3) formula are shown in Table 1. The inventors of the present invention used a plurality of solid wires different in Si + 0.5 x (Mn + Cr) + 0.3 x Ni, and performed gas shielded arc welding under the same conditions. Then, the gap between the steel plates (the gap between the steel plates) that these solid wires could weld was investigated. Specifically, the lap fillet welds were performed on the plate group in which the gap between the steel plates 2 shown in Table 1 gradually widened, and the limit value of the gap between the steel plates from which a good welded portion could be obtained was found. Figure 4 Figure 3A In Table 1, "good welded portion" means the welded portion in which the weld metal 1 is formed to the upper end of the upper plate end surface.

[0073] Figure 1 ​is a graph with Si + 0.5 x (Mn + Cr) + 0.3 x Ni of the solid core wire as the horizontal axis and the upper limit of the gap (i.e., the upper limit of the gap at which a good welded joint can be obtained) as the vertical axis. As shown in Figure 1 As shown in FIG. 1, it is understood that by setting Si + 0.5 x (Mn + Cr) + 0.3 x Ni to 1.00% or more in the solid core wire, good gap weldability can be ensured.

[0074] (3. Spatter resistance)

[0075] Regarding the reduction of spatter at the time of welding work, for example, improvement can be made by optimization of welding conditions such as an increase in welding voltage. However, if the welding voltage is increased, the welding heat input increases, and thus it can become a cause of reduction in gap weldability and burning through (piercing) of the steel sheet. Therefore, it is preferable that spatter be reduced by improvement of the welding wire.

[0076] The inventors of the present application have repeatedly studied the cause of spatter by observing the behavior of molten metal at the time of gas shielded arc welding using a high-speed video camera. As a result, it was found that in the solid core wire in which Si is reduced in order to improve electrodeposition painting properties, droplet transfer becomes unstable. Droplet refers to a droplet of molten metal formed by melting the tip of the welding wire by heat of an arc or the like. Droplet transfer refers to the phenomenon in which the droplet passes through the arc generation portion and is transferred from the melting electrode toward the molten pool.

[0077] Generally, in welding of automobile parts and the like, in gas shielded arc welding, pulsed MAG welding in which the welding current value is periodically varied is employed. In pulsed MAG welding, a droplet is formed at the tip of the solid core wire when the welding current value is high, and the droplet separates from the tip of the solid core wire when the welding current value is low, which is an ideal droplet transfer phenomenon. That is, it is preferable that the period of droplet transfer coincide with the period of increase and decrease of the welding current value.

[0078] However, the inventors of the present application have recognized that the lower the Si of the solid core wire, the more difficult the droplet becomes to separate from the tip of the solid core wire. If the droplet becomes difficult to separate from the tip of the solid core wire, the period of droplet transfer becomes difficult to coincide with the period of increase and decrease of the welding current value. Thus, the inventors of the present application have found that spatter is generated when the periods of the two deviate.

[0079] Next, the inventors of the present application have repeatedly studied a method of promoting separation of the droplet. Thus, the inventors of the present application have considered that the surface tension and viscosity of the droplet have an influence on the separation characteristics of the droplet. In the solid core wire in which the Si content is reduced in order to improve electrodeposition painting properties, as shown in FIG. 2, it is confirmed that the droplet 5 at the tip of the solid core wire 4 is extended in a necked state, and the separation of the droplet is hindered. Figure 5A Figure 5A ​The phenomenon shown is presumed to result in the following: if the Si content of droplet 5 is low, the oxygen content of droplet 5 increases due to insufficient deoxidation, and the surface tension of droplet 5 decreases.

[0080] If the Si content is increased to improve the surface tension of droplet 5, then as Figure 5B As shown, the molten droplet 5 separates into spherical particles, improving the droplet transition characteristics. However, in the research of the inventors of this invention, in order to improve the separation characteristics of the molten droplet 5 solely through the Si content, it is necessary to contain approximately 0.3% by mass Si in the solid wire 4. This results in compromised electrodeposition coating properties.

[0081] Therefore, the inventors of this invention focused on viscosity as another factor affecting droplet separation characteristics. Specifically, by including appropriate amounts of Si and Mn in the solid wire 4, deoxidation of the droplet 5 is promoted, thereby increasing the surface tension of the droplet 5. Furthermore, by including appropriate amounts of C in the solid wire 4, the viscosity of the droplet 5 is reduced, thereby improving the droplet's fluidity. Through the synergistic effect of these actions, an attempt is made to promote... Figure 5B The stable droplet separation shown in the figure.

[0082] Based on the above insights, the inventors of this invention discovered the following formula (6).

[0083] 0.16≤C×(5×Si+Mn)≤0.35 (6)

[0084] In equation (6), "C×(5×Si+Mn)" is an indicator of the viscosity of the molten droplets generated by the melting of solid welding wire. C reduces the viscosity of the droplets. The larger (5×Si+Mn) is, the more it promotes the deoxidation of the droplets, and the more the surface tension of the droplets increases. By controlling the chemical composition of the solid welding wire in accordance with equation (6), the solid welding wire can be appropriately filled with C, Si, and Mn, thereby stabilizing the droplet transition and reducing the amount of spatter.

[0085] exist Figure 2 The experimental results of the inventors of the present invention regarding the effect of formula (6) are shown in the figure. The inventors of the present invention performed gas shielded arc welding under the same conditions using multiple solid welding wires of different C×(5×Si+Mn). Then, the number of spatters adhering to the surface of the steel plate was counted. Figure 2 This is a graph with the C×(5×Si+Mn) of the solid welding wire on the horizontal axis and the number of spatters adhering to the surface of the steel plate on the vertical axis. For example... Figure 2 As shown, if a solid wire with C×(5×Si+Mn) set in the range of 0.16 to 0.35 is used, the amount of spatter can be significantly reduced.

[0086] (4. Manufacturability of solid welding wire)

[0087] For the solid wire in which the Si content is reduced in order to improve the electrodeposition paintability, it is necessary to contain alloying elements for increasing the electric resistance and reducing the stickiness of the molten droplet. In addition, it is necessary to contain Ti in the solid wire in order to reduce the electric resistance of the slag. However, these alloying elements increase the hardness of the solid wire and the wire material of the solid wire. The more the hardness of the wire increases, the more the wire is likely to be broken when the wire is subjected to the wire drawing process to obtain the solid wire.

[0088] Therefore, the inventors of the present application further control the chemical components of the solid wire by the following (4) formula.

[0089] 0.30 ≤ C + Mn / 6 + Si / 24 + Ni / 40 + Cr / 5 + Mo / 4 + V / 14 ≤ 0.55 (4) formula

[0090] The "C + Mn / 6 + Si / 24 + Ni / 40 + Cr / 5 + Mo / 4 + V / 14" contained in the (4) formula is the carbon equivalent Ceq. The higher the Ceq of the steel, the more the hardness of the steel increases. Therefore, in the solid wire of the present embodiment, the Ceq is set to be 0.55 mass% or less. Thereby, the wire is less likely to be broken when the solid wire is subjected to the wire drawing process, and the manufacturability of the solid wire is improved.

[0091] By satisfying the above-described (1) formula, (2) formula, (3) formula, and (4) formula, it is possible to obtain a solid wire which is easy to manufacture, in which the welding failure in the plate set having a large gap can be avoided, and in which a welded joint having high electrodeposition paintability can be manufactured. In addition, by satisfying the (6) formula, it is possible to give the solid wire a spatter suppression effect.

[0092] Next, a specific aspect of the solid wire of the present embodiment will be described. The inventors of the present application determined the component composition of the solid wire for gas shielded arc welding based on the above-described knowledge and other various situations. The solid wire for gas shielded arc welding of the present embodiment achieves its effect by the synergistic effect of each component composition, and the reasons for the limitation of each component composition will be described below.

[0093] The content of the alloying elements described below is all mass% with respect to the total mass of the solid wire. In the case where the solid wire has a plated layer such as copper plating, the value obtained by dividing the mass of the alloying element contained in the entire solid wire including the plated layer by the total mass of the solid wire including the plated layer is the mass% of the alloying element with respect to the total mass of the solid wire. Hereinafter, the mass% with respect to the total mass of the solid wire will be simply referred to as "%". In addition, the unit "mass%" of the carbon equivalent Ceq is also simply referred to as "%" in the present disclosure.

[0094] [C: 0.04 to 0.12%]

[0095] C is an element that improves the strength of the weld metal. By setting the C content to 0.04% or more, the strength of the weld metal can be improved. Further, C has an effect of reducing the viscosity of the droplet formed by melting of the solid wire. Thereby, the droplet transfer is stabilized, and the spatter amount can be suppressed. By setting the C content to 0.04% or more, the above-mentioned effect can be obtained. Further, it is preferable to set the C amount to 0.06% or more.

[0096] On the other hand, if the C content exceeds 0.12%, the solid wire raw material hardens, and the wire drawing property of the solid wire decreases. Therefore, the C content is set to 0.12% or less. Further, it is preferable to set the C content to 0.10% or less.

[0097] [Si: 0.13 to 0.28%]

[0098] Si in the solid wire is an element having a deoxidizing effect, and combines with oxygen in the molten pool to form a slag at the time of gas shielded arc welding. The slag is discharged outside the weld metal at the time of solidification of the molten pool to form the weld metal. Therefore, Si has an effect of reducing the oxygen amount of the weld metal. In a general solid wire, Si is actively added as a deoxidizing element.

[0099] However, the slag having Si as a main component has a high electric resistance value. The slag having a high electric resistance value hinders the coating film from adhering to the weld metal, the steel sheet at the time of electrodeposition coating. Therefore, the slag having Si as a main component causes poor electrodeposition coating of the welded joint. From the viewpoint of improving the electrodeposition coating property, it is preferable to reduce the Si content of the molten pool. Therefore, the Si content of the solid wire is set to 0.28% or less. It is preferable to set the Si content to 0.25% or less, 0.22% or less, 0.20% or less, 0.19% or less, or 0.18% or less.

[0100] On the other hand, if the Si content of the solid wire is excessively reduced, the electric resistance value of the solid wire is insufficient. The lower the electric resistance value of the solid wire, the more difficult the solid wire becomes to melt, and the more deteriorated the gap welding property of the steel sheet becomes. In addition, if the Si content of the solid wire is excessively reduced, the surface tension of the droplet formed by melting of the solid wire becomes low, the droplet transfer is destabilized, and the spatter amount increases. In the solid wire of the present embodiment, by using elements other than Si in a manner satisfying the formula (3) and preferably the formula (6), the adverse effects caused by reduction of Si are mitigated. However, in the case where the Si content is less than 0.13%, the above-mentioned adverse effects are significantly exhibited. Therefore, the Si content of the solid wire is set to 0.13% or more. As needed, the Si content can be set to 0.15% or more, 0.18% or more, or 0.20% or more.

[0101] [Mn: 1.4 to 2.3%]

[0102] As with Si, Mn is also a deoxidizing element. Mn promotes deoxidization of the molten pool during arc welding. Furthermore, Mn also has the effect of increasing the tensile strength of the weld metal. In addition, Mn also has the effect of promoting the resistance heating of the solid wire to improve the gap welding property. Furthermore, Mn also has the effect of stabilizing the transfer of the droplet by increasing the surface tension through the deoxidizing action of the droplet. Therefore, the Mn content of the solid wire is set to 1.4% or more. The Mn content is preferably 1.5% or more, 1.6% or more, 1.7% or more, or 1.8% or more.

[0103] On the other hand, in the case where the Mn content is excessive, it is possible that the insulating Mn-based dross is significantly generated on the surface of the weld metal, resulting in poor electrodeposition coating. In addition, in the case where the Mn content is excessive, it is possible that the wire as a material of the solid wire is excessively hardened, and the manufacturability of the solid wire is impaired. Therefore, the Mn content of the solid wire is 2.3% or less. The Mn content is preferably 2.2% or less, 2.1% or less, or 2.0% or less.

[0104] 〔Ti: 0.13 to 0.25%〕

[0105] Ti generates Ti-based dross with Ti oxide as the main component at the time of gas shielded arc welding. The Ti-based dross is conductive unlike the Si, Mn-based dross. The conductive Ti-based dross is less likely to cause poor electrodeposition coating. Therefore, Ti can improve the electrodeposition coating property of the solid wire. In addition, Ti also has the effect of suppressing the generation of pores. For the above reasons, the Ti content of the solid wire is set to 0.13% or more. The Ti content is preferably set to 0.15% or more, 0.18% or more, or 0.20% or more.

[0106] On the other hand, if the Ti content is excessive, it is possible that the Ti-based oxide is excessively generated, and the elongation of the weld metal decreases. Therefore, the Ti content is set to 0.25% or less. The Ti content is preferably set to 0.24% or less, 0.23% or less, or 0.21% or less.

[0107] 〔Al: 0.001 to 0.050%〕

[0108] Al has a deoxidizing effect. Al improves the tensile strength of the weld metal by promoting deoxidization of the molten pool. In addition, Al, like Ti, reduces the amount of Si, Mn-based dross generated, and can improve the electrodeposition coating property. Therefore, the Al content of the solid wire is 0.001% or more. The Al content is preferably set to 0.010% or more, 0.015% or more, or 0.018% or more.

[0109] On the other hand, if the content of Al is excessive, Al-based oxides are excessively generated, and the elongation of the weld metal decreases. In addition, the Al-based slag is also insulating like the Si-based slag and the Mn-based slag. If the Al-based slag is significantly generated on the surface of the weld metal, it is possible that poor electrodeposition coating is generated. Therefore, the content of Al in the solid wire is 0.050% or less. The content of Al is preferably set to 0.030% or less or 0.020% or less.

[0110] 〔0 ≤ Cr + Ni ≤ 3.00〕

[0111] Cr and Ni are not necessary to solve the problems of the solid wire of the present embodiment. In the solid wire of the present embodiment, the lower limit value of the content of Cr is 0%, and the lower limit value of the content of Ni is 0%. The lower limit value of the total content of Cr and Ni is also 0%.

[0112] On the other hand, Cr and Ni are elements that increase the resistance of the solid wire and promote the melting of the solid wire. In addition, Cr and Ni also have the effect of improving the mechanical properties of the weld metal. Therefore, it is preferable that the solid wire contain at least one of Cr and Ni. It is preferable that both Cr and Ni be contained in the solid wire. If the total content of Cr and Ni is 0.05% or more, the above-described effects can be obtained. Therefore, the contents of Cr and Ni are preferably 0.05% or more in total. The contents of Cr and Ni are more preferably set to 0.10% or more, 0.15% or more, or 0.30% or more in total.

[0113] On the other hand, if the contents of Cr and Ni are excessive, it is possible that the elongation of the weld metal decreases and the weld metal cracks. In addition, if the contents of Cr and Ni are excessive, the hardness of the wire as a material of the solid wire can become excessive, and the workability of the solid wire is impaired. Therefore, the contents of Cr and Ni are 3.00% or less in total. The contents of Cr and Ni are preferably set to 2.50% or less, 2.00% or less, or 1.00% or less in total.

[0114] Therefore, the solid wire satisfies formula (5).

[0115] 0 ≤ Cr + Ni ≤ 3.00 (5)

[0116] wherein the element symbols in formula (5) are the contents of the respective elements in mass% with respect to the total mass of the solid wire. The values on the left and right of formula (5) can be replaced with the above-described preferable upper and lower limit values of the total content of Cr and Ni. For example, the solid wire can satisfy formula (9) instead of satisfying formula (5).

[0117] 0.05 ≤ Cr + Ni ≤ 3.00 (9)

[0118] 〔Cr: 0 to 3.00%〕

[0119] Not only the total content of Cr and Ni is set to the above range, but also the content of Cr is set to 0 to 3.00%. The content of Cr can be specified to 0.05 to 1.50%. The content of Cr is preferably 0.05% or more, 0.11% or more, 0.15% or more, or 0.20% or more. The content of Cr is preferably 2.50% or less, 2.00% or less, 1.50% or less, 1.20% or less, 1.00% or less, 0.50% or less, less than 0.50%, 0.45% or less, or 0.40% or less.

[0120] 〔Ni: 0 to 3.00%〕

[0121] Further, not only the total content of Cr and Ni is set to the above range, but also the content of Ni is set to 0 to 3.00%. The content of Ni can be specified to 0.05 to 3.00%. The content of Ni is preferably 0.05% or more, 0.08% or more, 0.10% or more, or 0.20% or more. The content of Ni is preferably 2.50% or less, 2.00% or less, 1.50% or less, 1.20% or less, 1.00% or less, 0.50% or less, 0.45% or less, or 0.40% or less.

[0122] 〔P: 0.020% or less〕

[0123] P is an element that is generally mixed as an impurity in steel, and is also generally contained as an impurity in the solid wire for electric arc welding. Here, P is one of the main elements that cause high-temperature cracking of the weld metal, and it is thus preferable to be suppressed as much as possible. If the content of P exceeds 0.020%, high-temperature cracking of the weld metal becomes significant. Therefore, the content of P in the solid wire is 0.020% or less. The content of P is preferably set to 0.015% or less, 0.012% or less, or 0.010% or less.

[0124] P does not contribute to the solution of the problems of the present disclosure. Therefore, the content of P in the solid wire can also be 0%. However, considering the refining cost, the content of P in the solid wire can also be set to more than 0%. The content of P can also be 0.001% or more, 0.002% or more, or 0.005% or more.

[0125] 〔S: 0.015% or less〕

[0126] S is also an element that is generally mixed as an impurity in steel, and is also generally contained as an impurity in the solid wire for arc welding. Therefore, the S content of the solid wire is 0.015% or less. The S content is preferably set to 0.012% or less, 0.010% or less, or 0.008% or less. The S content can also be 0%, but the S content can also be set to more than 0% or 0.001% or more in consideration of the refining cost.

[0127] [N: 0.006% or less]

[0128] N is also an element that is generally mixed as an impurity in steel, and is also generally contained as an impurity in the solid wire for arc welding. Excessive N decreases the toughness of the weld metal and becomes a cause of pore defects in the weld metal. Therefore, the N content of the solid wire is set to 0.006% or less. The N content is preferably set to 0.005% or less or 0.004% or less. The N content can also be 0%, but the N content can also be set to more than 0% or 0.001% or more in consideration of the refining cost.

[0129] Mo, B, Cu, Nb, and V are not elements that are essential to solve the problems of the present disclosure. Therefore, the lower limit value of the content of these elements is 0%. On the other hand, by containing one or more of these elements in the solid wire, the performance of the solid wire can be further improved.

[0130] [Mo: 0 to 0.5%]

[0131] The Mo content of the solid wire can also be 0%. However, Mo increases the tensile strength in order to increase the hardenability of the welded portion, and the Mo content of the solid wire can also be set to 0.1% or more, 0.2% or more, or 0.3% or more as needed. On the other hand, in order to ensure the ductility of the welded portion, the Mo content of the solid wire is set to 0.5% or less. The Mo content can also be set to 0.4% or less or 0.3% or less as needed.

[0132] [B: 0 to 0.0100%]

[0133] The B content of the solid wire can also be 0%. However, B increases the tensile strength in order to increase the hardenability of the welded portion, and the B content of the solid wire can also be set to 0.0010% or more, 0.0020% or more, or 0.0030% or more as needed. On the other hand, in order to ensure the ductility of the welded portion, the B content of the solid wire is set to 0.0100% or less. The B content can also be set to 0.0090% or less or 0.0070% or less as needed.

[0134] [Cu: 0 to 0.50%]

[0135] The Cu content of the solid wire can also be 0%. However, copper plating provided on the solid wire for arc welding has the effect of stabilizing wire feeding and current feeding, and thus the Cu content of the solid wire can also be set to 0.10% or more, 0.15% or more, or 0.18% or more, as needed. On the other hand, the Cu content of the solid wire is set to 0.50% or less from the viewpoint of suppressing cracking during welding. The Cu content can also be set to 0.40% or less or 0.30% or less, as needed.

[0136] [Nb: 0 to 0.30%]

[0137] The Nb content of the solid wire can also be 0%. However, Nb has the effect of improving the hardenability of the welded portion and thus the tensile strength, and thus the Nb content of the solid wire can also be set to 0.05%, 0.10% or more, or 0.12% or more, as needed. On the other hand, the Nb content of the solid wire is set to 0.30% or less from the viewpoint of ensuring the ductility of the welded portion. The Nb content can also be set to 0.25% or less, 0.20% or less, or 0.12% or less, as needed.

[0138] [V: 0 to 0.5%]

[0139] The V content of the solid wire can also be 0%. However, V has the effect of improving the hardenability of the welded portion and thus the tensile strength, and thus the V content of the solid wire can also be set to 0.05% or more, 0.1% or more, or 0.12% or more, as needed. On the other hand, the V content is set to 0.5% or less from the viewpoint of ensuring the ductility of the welded portion. The V content can also be set to 0.30% or less or 0.20% or less, as needed.

[0140] (Zr: 0 to 0.20%)

[0141] The Zr content of the solid wire can also be 0%. However, Zr has the effect of improving the toughness of the welded metal by reducing the oxygen content of the welded metal through a deoxidizing effect, and thus the Zr content of the solid wire can also be set to 0.01% or more, 0.05% or more, or 0.08% or more, as needed. On the other hand, the upper limit of the Zr content is set to 0.20% in order to suppress the generation of coarse inclusions (inclusions having an equivalent circle diameter of 5 μm or more). The Zr content can also be set to 0.18% or less, 0.15% or less, 0.10% or less, or 0.05% or less, as needed.

[0142] (Mg: 0 to 0.050%)

[0143] The Mg content of the solid wire can also be 0%. However, Mg improves the toughness of the weld metal because it reduces the oxygen content of the weld metal through a deoxidizing effect, and therefore the Mg content of the solid wire can also be set to 0.001% or more, 0.003% or more, or 0.005% or more, as needed. On the other hand, by reducing the Mg content, the amount of slag that is generated is reduced, and welding defects such as slag entrapment can be suppressed, and therefore the Mg content is set to 0.050% or less. The Mg content can also be set to 0.040% or less, 0.030% or less, 0.010% or less, or 0.008% or less, as needed.

[0144] (As: 0 to 0.020%)

[0145] As is an element that is mixed as an impurity in steel, and it is also possible for As to be included as an impurity in the solid wire for arc welding. Here, As is one of the elements that reduce the toughness of the weld metal because it segregates at the grain boundaries when the weld metal solidifies, and therefore it is preferable to suppress As as much as possible. Therefore, the As content of the solid wire is 0.020% or less. The As content can also be set to 0.015% or less, 0.012% or less, or 0.010% or less. On the other hand, from the viewpoint of reducing refining costs, the As content can be set to more than 0%, 0.001% or more, 0.005% or more, or 0.008% or more.

[0146] (Sn: 0 to 0.100%)

[0147] The Sn content of the solid wire can also be 0%. However, Sn is an element that improves the corrosion resistance of the weld metal, and therefore the Sn content of the solid wire can also be set to 0.001% or more, 0.005% or more, or 0.010% or more, as needed. On the other hand, by reducing the Sn content of the wire, the generation of cracks in the weld metal is suppressed, and therefore the Sn content is set to 0.100% or less. The Sn content can also be set to 0.080% or less, 0.050% or less, or 0.020% or less, as needed.

[0148] (Sb: 0 to 0.10%)

[0149] The Sb content of the solid wire can also be 0%. However, Sb has the effect of promoting the flow of molten metal and expelling impurity elements to the surface of the molten metal as a surface-active element, and therefore the Sb content of the solid wire can also be set to 0.001% or more, 0.005% or more, or 0.01% or more, as needed. On the other hand, by reducing the Sb content of the wire, the generation of cracks in the weld metal is suppressed, and therefore the Sb content is set to 0.10% or less. The Sb content can also be set to 0.08% or less, 0.05% or less, or 0.02% or less, as needed.

[0150] The remaining portion of the above-described components has iron (Fe) and impurities. The impurities refer to components contained in raw materials, components mixed in during manufacturing, and components contained in the solid core welding wire within a range that does not adversely affect the solid core welding wire.

[0151] The chemical components of the solid core welding wire of the present embodiment further satisfy the following (1) formula, (2) formula, (3) formula, and (4) formula. It is preferable that the chemical components of the solid core welding wire of the present embodiment also satisfy the (6) formula. Note that the element symbols in the (1) formula, (2) formula, (3) formula, (4) formula, and (6) formula are the contents of each element in mass% with respect to the total mass of the above-described solid core welding wire.

[0152] (Si x Mn: 0.60 or less)

[0153] As described above, Si and Mn are elements that adversely affect electrodeposition paintability, but the degree of deterioration of paintability due to Mn dross is small in a component system in which Si is small. Therefore, in the solid core welding wire of the present embodiment, the contents of Si and Mn are set in a manner that satisfies the following (1) formula.

[0154] Si x Mn ≤ 0.60 (1) formula

[0155] In a case where the value of Si x Mn exceeds 0.60, Si-based dross and Si-Mn-based dross that are insulating significantly occur on the surface of a weld bead, and thus it is possible that electrodeposition paintability is deteriorated. Therefore, Si x Mn is 0.60 or less. Si x Mn is preferably 0.55 or less, 0.50 or less, or 0.45 or less. The lower limit value of Si x Mn is not particularly limited, but is, for example, 0.23 or more, 0.24 or more, or 0.25 or more.

[0156] ((Si + Mn / 5) / (Ti + Al): 4.0 or less)

[0157] As described above, Ti and Al are elements that can suppress adverse effects of Si and Mn-based dross on electrodeposition paintability. Therefore, in the solid core welding wire of the present embodiment, the contents of Si, Mn, Ti, and Al are set in a manner that satisfies the following (2) formula.

[0158] (Si + Mn / 5) / (Ti + Al) ≤ 4.0 (2) formula

[0159] In the case where the value of (Si + Mn / 5) / (Ti + Al) is 4.0 or less, the adverse effect of Si, Mn-based slag on electrodeposition paintability can be reliably suppressed, and excellent electrodeposition paintability can be obtained. The value of (Si + Mn / 5) / (Ti + Al) is preferably 3.5 or less, 3.0 or less, or 2.5 or less. The lower limit of (Si + Mn / 5) / (Ti + Al) is not particularly limited, but for example, (Si + Mn / 5) / (Ti + Al) can be set to 1.3 or more, 1.5 or more, or 2.0 or more.

[0160] Note that the product of Si and Mn is used as an index in the formula (1), but the sum of Si and Mn / 5 is used as an index in the formula (2). This is because Ti and Al are used for the purpose of reducing the absolute amount of Si-Mn-based slag.

[0161] (Si + 0.5 x (Mn + Cr) + 0.3 x Ni: 1.00% or more)

[0162] As described above, Si + 0.5 x (Mn + Cr) + 0.3 x Ni is an index of the resistance value of the solid wire. If the resistance value of the solid wire is too low, the resistance heat generation amount of the solid wire becomes small, and the solid wire becomes difficult to melt. As a result, the gap welding property is impaired. In order to improve the gap welding property, the chemical composition of the solid wire is selected in such a manner as to satisfy the following formula (3).

[0163] 1.00 ≤ Si + 0.5 x (Mn + Cr) + 0.3 x Ni (3)

[0164] Si + 0.5 x (Mn + Cr) + 0.3 x Ni can also be 1.10% or more, 1.20% or more, 1.30% or more, or 1.40% or more. The upper limit of Si + 0.5 x (Mn + Cr) + 0.3 x Ni is not particularly limited. From the viewpoint of ensuring the manufacturability of the solid wire, Si + 0.5 x (Mn + Cr) + 0.3 x Ni can be set to 2.00% or less, 1.90% or less, 1.80% or less, or 1.60% or less.

[0165] (C x (5 x Si + Mn): preferably 0.16 to 0.35)

[0166] As described above, C x (5 x Si + Mn) is an index of the viscosity of the droplet formed by melting of the solid wire. The larger C x (5 x Si + Mn) is, the more the surface tension of the droplet increases, and the viscosity of the droplet decreases, and the droplet transfer is more stabilized. As a result, spatter is reduced. Therefore, the chemical composition of the solid wire of the present embodiment is preferably selected in such a manner as to satisfy the following formula (6).

[0167] 0.16 ≤ C x (5 x Si + Mn) ≤ 0.35 (6)

[0168] C x (5 x Si + Mn) can also be 0.18 or more, 0.19 or more, or 0.20 or more. On the other hand, if C x (5 x Si + Mn) is excessive, the stability of droplet transfer is reduced. Therefore, C x (5 x Si + Mn) is preferably set to 0.35 or less. Further preferably, C x (5 x Si + Mn) is 0.30 or less, 0.25 or less, or 0.22 or less.

[0169] (Ceq: 0.30 to 0.55%)

[0170] As described above, C + Mn / 6 + Si / 24 + Ni / 40 + Cr / 5 + Mo / 4 + V / 14 is the carbon equivalent Ceq of the solid wire. By reducing Ceq, the hardness of the wire as a raw material of the solid wire is reduced, and the manufacturability of the solid wire can be improved. Therefore, the chemical components of the solid wire of the present embodiment are selected in a manner so as to satisfy the following (4) formula.

[0171] 0.30 ≤ C + Mn / 6 + Si / 24 + Ni / 40 + Cr / 5 + Mo / 4 + V / 14 ≤ 0.55 (4) formula

[0172] Ceq is preferably 0.55% or less, 0.50% or less, or 0.45% or less. On the other hand, from the viewpoint of improving the strength of the weld metal, Ceq is set to 0.30% or more. Ceq is preferably 0.32% or more, 0.35% or more, or 0.38% or more.

[0173] (H2≥ 250)

[0174] (H2 - H1≥ 40)

[0175] The present inventors have found that there is a correlation between the amount of spatter generated at the time of welding and the mechanical properties of the solid wire. In order to reduce the amount of spatter, it is necessary to set the wire feed speed to be substantially constant. The wire feed speed refers to the length of the wire fed per unit time. By increasing the strength of the solid wire, the deformation of the solid wire can be suppressed. If the amount of deformation of the solid wire is reduced, the friction of the solid wire within the wire line can be suppressed. If the friction of the solid wire is suppressed, the variation in the wire feed speed can be suppressed. That is, by increasing the strength of the wire, it is possible to set the wire feed speed to be substantially constant, and further suppress the amount of spatter.

[0176] On the other hand, the inventors of the present application have also found that excessive hardening of the solid wire increases the amount of spatter. The solid wire that is excessively hardened promotes wear of the electrode tip. The wear of the electrode tip causes variation in the position of the power feeding point. The power feeding point refers to the contact point for passing the solid wire through the electrode tip and feeding power. Generally, the front end of the power feeding tip becomes the power feeding point. Variation in the position of the power feeding point increases the amount of spatter.

[0177] As a result of the above studies, the inventors of the present application have found that increasing the hardness of the inside of the solid wire and softening the surface layer are extremely effective in suppressing spatter. Therefore, it is preferable that, in the solid wire of the present embodiment, the hardness determined in the cross section of the solid wire satisfies the following (7) and (8).

[0178] H2≥ 250 (7)

[0179] H2- H1≥ 40 (8)

[0180] In the (8), the symbol H1 is the Vickers hardness determined at a position at a depth of 0.05 mm from the surface of the solid wire. The symbol H2 in the (7) and the (8) is the average of the Vickers hardness determined at positions at depths of 0.25 mm and 0.35 mm from the surface. Note that the Vickers hardness is HV0.3 of JIS Z2244-1:2024. HV0.3 refers to the Vickers hardness determined by a Vickers test in which the test force is set to 2.942 N (300 gf). In addition, when a plated layer is provided on the surface of the solid wire, the surface of the solid wire refers to the interface between the plated layer and the base (the iron portion that is the base, which corresponds to the portion of the steel wire without the plated layer).

[0181] H2 represents the hardness of the inside of the solid wire. The hardness of the inside of the solid wire that satisfies the (7) is sufficiently increased. Therefore, in welding using the solid wire that satisfies the (7), the wire feed speed is stabilized, and the amount of spatter can be further suppressed.

[0182] H1 represents the hardness of the surface layer of the solid wire. H2- H1 represents the degree of softening of the surface layer of the solid wire. The greater H2- H1 is, the more the surface layer of the solid wire is softened. Therefore, in welding using the solid wire that satisfies the (8), the wear of the electrode tip is suppressed, and the amount of spatter can be further suppressed.

[0183] As described above, if the solid wire satisfies the formulas (7) and (8), the amount of spatter generation can be further suppressed, and thus is very preferable. However, even if the solid wire does not satisfy the formulas (7) and (8), the amount of spatter generation is suppressed to a degree required in practice, and thus as the solid wire of the present embodiment, it is not necessary to exclude the solid wire that does not satisfy the formulas (7) and (8).

[0184] The solid wire satisfying the formulas (7) and (8) is obtained, for example, by a manufacturing method having the following steps:

[0185] (S1) a step of performing primary drawing on a wire having the same composition as the solid wire of the present embodiment to obtain a primary drawn wire;

[0186] (S2) a step of annealing the primary drawn wire; and

[0187] (S3) a step of performing secondary drawing on the primary drawn wire to obtain the solid wire.

[0188] The annealing is performed under the following conditions.

[0189] • Annealing temperature: 650 to 900°C

[0190] • Annealing time: 10 to 30 minutes

[0191] • Product of annealing temperature (°C) and annealing time (min): 8400 to 25000 °C·min

[0192] • Dew point of annealing atmosphere: -10 to +10°C

[0193] The secondary drawing is performed under the following conditions.

[0194] • Area ratio of secondary drawn wire to primary drawn wire: 10 to 30%

[0195] That is, the area ratio A2 of the cross-sectional area Al of the primary drawn wire to the secondary drawn wire satisfies the following formula.

[0196] 0.10 ≤ A2 / Al ≤ 0.30

[0197] In order to confirm the effect of the hardness control of the solid wire, the following experiment was performed. The original wire was subjected to primary drawing by cold working, and after annealing in an intermediate step, secondary drawing was performed, whereby the solid wire was produced. In the annealing step, the temperature was set to 750 to 900°C, and the annealing time was set to 20 to 30 minutes. Furthermore, in the annealing step, by adding water vapor, hydrogen in a nitrogen atmosphere, the dew point was controlled in the range of -10 to +10°C. Note that in the production of Example A4, the pressure of the atmosphere was set to a reduced pressure atmosphere of about 1000 Pa.Figure 6 Examples of cross-sectional hardness of various welding wires. Figure 6 The horizontal axis of the graph is the distance from the measurement position of the Vickers hardness of the surface of the solid wire. Figure 6 The vertical axis of the graph is the hardness (HV0.3 of JIS Z2244-1:2024) of the solid wire at the measurement position.

[0198] Examples Al to A4 shown in the following table are examples in which the primary wire having the composition of Example No. 1 shown in Table 2A was subjected to one drawing process to a diameter of 1.2 mm and then subjected to annealing process under various conditions to produce a solid wire of Example No. 1. Examples Al to A4 shown in the following table are examples in which the primary wire having the composition of Example No. 1 shown in Table 2A was subjected to one drawing process to a diameter of 1.2 mm and then subjected to annealing process under various conditions to produce a solid wire of Example No. 1. The area ratio of the secondary drawing wire to the primary drawing wire at the time of production of Examples Al to A4 was 23%.

[0199] [Table 1]

[0200]

[0201] The "area ratio" is the area ratio of the secondary drawing wire to the primary drawing wire

[0202] Example No. Al is a secondary drawing wire obtained by subjecting the primary drawing wire to annealing at an atmosphere dew point of -10°C, an annealing temperature of 600°C, and an annealing time of 10 minutes. Example No. Al represents a hardness profile without surface layer softening and high hardness.

[0203] Example No. A2 is a secondary drawing wire obtained by subjecting the primary drawing wire to annealing at an atmosphere dew point of +5°C, an annealing temperature of 650°C, and an annealing time of 15 minutes. Example No. A2 is high hardness, and the surface layer is softened.

[0204] Example No. A3 is a secondary drawing wire obtained by subjecting the primary drawing wire to annealing at an atmosphere dew point of -7°C, an annealing temperature of 830°C, and an annealing time of 30 minutes. Example No. A3 has an increased degree of surface layer softening compared to Example No. A2, and the hardness of the inside of the wire is also slightly reduced.

[0205] Example No. A4 is a secondary drawing wire obtained by subjecting the primary drawing wire to annealing at an atmosphere dew point of -10°C, an annealing temperature of 900°C, and an annealing time of 30 minutes. Example No. A4 represents a hardness profile without surface layer softening and low hardness.

[0206] The spatter adhesion state at the time of welding using these solid wires A1 to A4 was investigated. As shown in Table 1, for the welding tests using the solid wires A1 and A4 that were not surface softened, the number of spatter adhesion was slightly large. In contrast, for the welding tests using the solid wires A2 and A3 that were surface softened, the number of spatter adhesion was extremely small. Based on these evaluation results, H2≥250 and H2-H1≥40 were set as the criteria for the wire hardness for spatter adhesion minimization.

[0207] The chemical components of the solid wire can be measured by a usual method. For example, the content of each element in mass% relative to the total mass of the solid wire can be found in accordance with JIS G 0321:2017 "Method of analysis of steel products and permissible variations thereof".

[0208] The inventors of the present application found the chemical components of the solid wire by wet chemical analysis of the solid wire that was cut to a length of several mm. Therefore, the content of the alloying elements in the present disclosure refers to the average value of the content of the alloying elements in the solid wire.

[0209] The diameter of the solid wire (diameter) is not particularly limited, but for example, it is preferably set to a range of 0.8 mm to 1.6 mm. Thereby, the workability of the solid wire in arc welding and the manufacturability of the solid wire can be further improved. The diameter of the solid wire can also be 0.9 mm or more, 1.0 mm or more, or 1.1 mm or more. The diameter of the solid wire can also be 1.5 mm or less, 1.4 mm or less, or 1.3 mm or less.

[0210] The solid wire is not only used for gas shielded arc welding, but also exists as a welding wire for submerged arc welding (SAW). However, the diameter of the welding wire for SAW is large, and the producer or user of the welding wire and the like can distinguish it from the solid wire for gas shielded arc welding by the diameter of the welding wire. Specifically, since the diameter of the welding wire for SAW does not become 1.4 mm or less, the producer or user of the welding wire and the like can recognize it as the solid wire for gas shielded arc welding as long as it is a welding wire having a diameter of 1.4 mm or less. In addition, even if the diameter of the welding wire is more than 1.4 mm, the producer or user of the welding wire and the like can easily judge whether it is the welding wire for SAW or the solid wire for gas shielded arc welding, depending on the display content in the package of the welding wire (the name or number of the specification of the welding wire), the name of the welding material or the product catalog of the welding material manufacturer, and the like.

[0211] The solid wire of the present embodiment is preferably applied to gas shielded arc welding of a steel sheet. For example, the manufacturing method of a welded joint including a step of performing gas shielded arc welding of a steel sheet using the solid wire for gas shielded arc welding of the present embodiment can suppress spatter, can avoid welding failure in a plate set having a large gap, and can manufacture a welded joint having high electrodeposited coating properties. The manufacturing method of a welded joint of the present embodiment is mainly targeted at underbody components of an automobile component. The steel sheet used as a welding base material is preferably set to a 440 MPa steel sheet to a 1180 MPa grade steel sheet. In addition, the thickness of the steel sheet used as a welding base material is preferably set to 1.0 mm to 3.5 mm.

[0212] Example

[0213] The effects of one aspect of the present disclosure are more specifically described through examples. However, the conditions in the examples are merely one example of conditions adopted in order to confirm the implementability and effects of the present disclosure. The present disclosure is not limited to this one example of conditions. Various conditions can be adopted as long as the present disclosure does not depart from the gist of the present disclosure and achieves the object of the present disclosure.

[0214] (Experiment 1)

[0215] Solid wires having various chemical compositions were trial-produced. The chemical compositions and calculated values of these solid wires are shown in Tables 2A, 2B, 3A, 3B, 4A, and 4B. The contents of the alloying elements described in Tables 2A to 3B are in mass %. The units of Ceq and “Si + 0.5 x (Mn + Cr) + 0.3 x Ni” described in Tables 4A and 4B are mass %. In addition, the remaining portion of the chemical composition described in Tables 2A to 3B is iron and impurities. Note that values outside the scope of the present disclosure are underlined. In addition, components not contained are set to be blank in the tables. Note that Cu of the solid wire is derived from Cu plating formed on the surface of the solid wire. Example 6 is a solid wire without Cu plating, and thus does not contain Cu.

[0216] The manufacturing method of the solid wire was set as follows. The raw steel melted in a vacuum was made into a raw wire by performing forging and rolling to a diameter of 2.0 mm. After that, the raw wire was annealed, and then fine drawn until the product diameter was 1.2 mm. Cu plating was not performed on Examples 6 and 17. Cu plating was performed on the surfaces of the solid wires other than these. The solid wire after fine drawing was made into a 20-kg reel as a trial product. Note that the annealing conditions (annealing temperature, annealing time, and annealing atmosphere) of the first drawing and the area ratio at the time of the second drawing were set to the same conditions as Example No. A3 of Table 1.

[0217] [Table 2A]

[0218] ​ No. C Si Mn Ti Al Cr Ni Cr+Ni 1 0.07 0.16 2.0 0.18 0.001 0.12 0.12 2 0.06 0.19 1.8 0.16 0.001 0.06 0.06 3 0.07 0.28 1.5 0.14 0.020 0.07 0.07 4 0.08 0.16 1.8 0.15 0.020 0.31 0.31 5 0.07 0.19 2.1 0.22 0.020 0.30 0.30 6 0.07 0.20 1.6 0.15 0.002 0.05 0.05 7 0.10 0.13 2.3 0.18 0.005 0.06 0.20 0.26 8 0.05 0.16 2.0 0.15 0.001 1.90 1.90 9 0.11 0.16 2.0 0.16 0.020 2.00 2.00 10 0.05 0.15 2.0 0.15 0.020 0.05 0.05 11 0.10 0.15 1.8 0.18 0.010 0.15 0.15 12 0.08 0.22 2.1 0.18 0.020 0.10 0.10 13 0.10 0.13 1.8 0.15 0.002 0.30 0.30 14 0.05 0.16 1.5 0.18 0.001 1.20 1.20 15 0.06 0.13 2.0 0.22 0.001 0.05 2.30 2.35 16 0.07 0.21 2.1 0.18 0.020 0.50 0.50 17 0.08 0.15 2.0 0.18 0.001 0.20 1.50 1.70 18 0.17 ]]> 1.5 ​ 0.17 1.5 0.18 0.020 0.05 0.05 19 0.14 ]]> ​ 0.20 2.2 0.19 0.002 0.20 0.10 0.30 20 0.12 0.13 2.1 0.20 0.005 0.06 3.20 3.26 ]]> ​ 21 0.08 0.13 1.4 0.20 0.005 0.06 0.06 22 0.07 0.14 1.5 0.16 0.020 0.05 0.05 23 0.08 0.13 1.5 0.16 0.001 24 0.08 0.23 2.3 0.16 0.001 25 0.08 0.32 ]]> ​ 1.8 0.17 0.001 26 0.08 0.25 2.5 ]]> ​ 0.18 0.002 27 0.11 0.18 2.2 0.12 ]]> ​ 0.002 0.50 0.50

[0219] [Table 2B]

[0220] No. C Si Mn Ti Al Cr Ni Cr+Ni 28 0.08 0.16 2.0 0.21 0.020 0.12 0.12 29 0.07 0.18 1.8 0.18 0.002 0.15 0.15 30 0.05 0.13 1.8 0.14 0.002 0.05 0.02 0.07 31 0.07 0.19 2.0 0.23 0.020 0.07 0.07 32 0.10 0.19 1.7 0.20 0.002 0.10 0.10 0.20 33 0.07 0.13 2.0 0.15 0.020 0.05 0.05 34 0.07 0.14 1.8 0.19 0.002 35 0.06 0.13 1.8 0.15 0.003

[0221] Table 3A

[0222] No. P S N B Mo Cu Nb V Zr Mg As Sn Sb 1 0.011 0.009 0.0032 0.31 2 0.011 0.001 0.0032 0.29 3 0.012 0.009 0.0033 0.28 0.2 4 0.014 0.011 0.0032 0.28 5 0.011 0.008 0.0032 0.0041 0.32 6 0.014 0.011 0.0035 0.1 0.1 7 0.011 0.007 0.0045 0.21 8 0.011 0.009 0.0042 0.0031 0.31 9 0.008 0.009 0.0031 0.48 10 0.012 0.008 0.0033 0.0032 0.32 11 0.011 0.011 0.0051 0.3 0.31 12 0.012 0.007 0.0033 0.31 0.14 0.2 13 0.011 0.008 0.0032 0.29 14 0.014 0.008 0.0031 0.31 15 0.008 0.009 0.0032 0.28 16 0.007 0.008 0.0030 0.3 0.27 17 0.013 0.011 0.0035 0.0033 0.025 18 0.011 0.008 0.0032 0.31 19 0.012 0.007 0.0033 0.31 20 0.011 0.008 0.0033 0.32 21 0.011 0.007 0.0031 0.31 22 0.012 0.008 0.0032 0.29 23 0.011 0.008 0.0031 0.29 24 0.013 0.009 0.0033 0.32 25 0.012 0.007 0.0032 0.31 26 0.011 0.008 0.0033 0.33 27 0.014 0.007 0.0032 0.31

[0223] Table 3B

[0224] No. P S N B Mo Cu Nb V Zr Mg As Sn Sb 28 0.012 0.008 0.0048 0.0041 0.29 0.11 0.07 29 0.008 0.003 0.0031 0.0032 0.32 0.004 0.004 30 0.011 0.008 0.0034 0.33 0.18 0.04 31 0.013 0.004 0.0057 0.0042 0.2 0.46 0.05 32 0.014 0.014 0.0041 0.0047 0.37 33 0.011 0.002 0.0032 0.0034 0.33 0.05 34 0.011 0.008 0.0035 0.0033 0.31 35 0.008 0.008 0.0031 0.0033 0.34

[0225] Table 4A

[0226] (4) Formula (1) Formula (2) Formula (3) Formula (6) Formula No. Ceq Si x Mn (Si + Mn / 5) / (Ti + Al) Si + 0.5 x (Mn + Cr) + 0.3 x Ni C x (5 x Si + Mn) 1 0.43 0.32 3.1 1.22 0.20 2 0.38 0.34 3.4 1.12 0.17 3 0.33 0.42 3.6 1.05 0.20 4 045 0.29 3.1 1.22 0.21 5 0.49 0.40 2.5 1.39 0.21 6 0.38 0.32 3.4 1.03 0.18 7 0.51 0.30 3.2 1.37 0.30 8 044 0.32 3.7 1.73 0.14 9 0.50 0.32 3.1 1.76 0.31 10 0.39 0.30 3.2 1.17 0.14 11 0.51 0.27 2.7 1.13 0.26 12 046 046 3.2 1.32 0.26 13 0.47 0.23 3.2 1.18 0.25 14 0.55 0.24 2.5 1.51 0.12 15 0.47 0.26 2.4 1.85 0.16 16 0.52 044 3.2 1.41 0.22 17 0.50 0.30 3.0 1.70 0.22 18 0.30 ]]> ​ 0.26 2.4 0.95 ]]> ​ 0.07 19 0.56 ]]> ​ 044 3.4 1.43 0.45 20 0.57 ]]> ​ 0.27 2.7 2.17 0.33 21 0.33 0.18 2.0 0.86 ]]> ​ 0.16 22 0.33 0.21 2.4 0.91 ]]> ​ 0.15 23 0.34 0.20 2.7 0.88 ]]> ​ 0.17 24 047 0.53 4.3 ]]> ​ 1.38 0.28 25 0.39 0.58 4.0 1.22 0.27 26 0.51 0.63 ]]> ​ 4.2 ]]> ​ 1.50 0.30 27 0.58 ]]> ​ 0.40 5.1 ]]> ​ 1.53 0.34

[0227] Table 4B

[0228] (4) Formula (1) Formula (2) Formula (3) Formula (6) Formula N0. Ceq Si x Mn (Si + Mn / 5) / (Ti + Al) Si + 0.5 x (Mn + Cr) + 0.3 x Ni C x (5 x Si + Mn) 28 0.44 0.32 2.4 1.22 0.22 29 0.38 0.32 3.0 1.13 0.19 30 0.37 0.23 3.5 1.06 0.12 31 0.48 0.38 2.4 1.23 0.21 32 0.41 0.32 2.6 1.12 0.27 33 0.42 0.26 3.1 1.16 0.19 34 0.38 0.25 2.6 1.04 0.18 35 0.37 0.23 3.2 1.03 0.15

[0229] Using prototype solid welding wire, lap fillet welds were performed on hot-rolled 440MPa grade steel plates (2.9mm thick) to investigate weldability of the gaps, spatter adhesion to the steel plates, and poor electrodeposition coating. In each case, the lap fillet welds were performed using pulsed MAG welding with Ar + 20% CO2 as the shielding gas.

[0230] (Investigation of weldability of plate gaps)

[0231] Implementation and use Figure 4 A conical test was conducted on a plate gap test piece with a gradually widening gap between the steel plates 2 as shown in the diagram. Lap fillet welds were performed with a 3mm thick spacer sandwiched between the ends of two test pieces with an overlapping length of 300mm. The settings were: welding current 260A, arc voltage 28.5V, and welding speed 100cm / min. Welding began at a plate gap of 0mm. After welding, the plate gap was... Figure 3A The extent of melting at the corner of the upper plate is considered good, and it will be as follows: Figure 3B If the corner of the upper plate is an unmelted area, it is considered defective. The upper limit of the weldable gap is determined and recorded in the "Conical Test Results" column of Tables 5A and 5B. Half the thickness of the steel plate is used as the criterion for judging the weldability of the gap. That is, a gap of 1.50 mm or more is considered acceptable.

[0232] (Investigation of splash adhesion amount)

[0233] A 120mm bead onplate weld was performed on a 150mm × 50mm steel plate test piece. The number of spatters larger than 0.3mm adhering to the steel plate surface was counted. The welding settings were: welding current 200A, arc voltage 23.5V, and welding speed 100cm / min. Four or fewer spatters were rated as Very Good, 5-7 as Good, and 8 or more as Normal. The results were compared and recorded in the "Spat Adhesion Amount" column of Tables 5A and 5B.

[0234] (Determination of the area ratio of poor electrodeposition coating)

[0235] After degreasing and chemical conversion treatment, the weld test pieces, prepared in a downward orientation, were electrodeposited to achieve a film thickness of 20 μm. The manufacturing conditions for the weld test pieces were set as follows: welding current 200 A, arc voltage 23.5 V, and welding speed 100 cm / min. The electrodeposited coating area of ​​the weld was then photographed, and the ratio of the area of ​​poor electrodeposited coating to the weld area was determined from the images. It should be noted that the weld length of the weld test pieces was set to 120 mm. Then, the defect rate of electrodeposited coating in the 90 mm length of the weld (excluding the 15 mm at the weld start and end) was calculated. A gray paint was used for electrodeposited coating. This made it easy to identify areas of poor electrodeposited coating and coated areas where reddish-brown or black slag was exposed. If the area of ​​poor coating was less than 5% (area ratio), the electrodeposited coating rate was considered good and recorded as "GOOD" in the "Poor Coating Area Ratio" column of Tables 5A and 5B. In cases of poor coating, the area percentage of poor coating shall be recorded in the "Area percentage of poor coating" column of Tables 5A and 5B.

[0236] Additionally, Tables 5A and 5B show the productivity of solid wire. Productivity is calculated from the output after annealing. Original thread fine drawing to The presence or absence of wire breakage was evaluated, and the results are recorded in the "Broken Wire Presence / Absence" column of Tables 5A and 5B. It should be noted that during annealing, the temperature history was managed by heating the original wire to 1200°C and then cooling it for 300 seconds from 800°C to 500°C. As shown in Tables 5A and 5B, the solid wire composition of this disclosure ensures stable productivity without wire breakage during drawing. On the other hand, wire breakage occurred in Comparative Examples 19, 20, and 27. It is presumed that in any of these examples, the hardening of the original wire caused by excessive Ceq was the cause of the breakage.

[0237] Table 5A

[0238]

[0239] Table 5B

[0240]

[0241] In the case of Example 18, the C content is not appropriate, and the formula (3) as an index of the gap weldability is not satisfied. Example 18 is not qualified with respect to the gap weldability.

[0242] In the case of Example 19, the C content is not appropriate, and the formula (4) as an index of the productivity is not satisfied. The welding wire of Example 19 has been broken during the manufacturing process.

[0243] In the case of Example 20, the total content of Cr and Ni is not appropriate, and the formula (4) as an index of the productivity is not satisfied. The welding wire of Example 20 has been broken during the manufacturing process.

[0244] In the case of Examples 21, 22 and 23, the formula (3) as an index of the gap weldability is not satisfied. Examples 21, 22 and 23 are not qualified with respect to the gap weldability.

[0245] In the case of Example 24, the formula (2) as an index of the painting property is not satisfied. Example 24 is not qualified with respect to the electrodeposition painting property.

[0246] In the case of Example 25, the Si content is not appropriate. Example 25 is not qualified with respect to the electrodeposition painting property.

[0247] In the case of Example 26, the Mn content is not appropriate, and the formulae (1) and (2) as indices of the painting property are not satisfied. Example 26 is not qualified with respect to the electrodeposition painting property.

[0248] In the case of Example 27, the Ti content is not appropriate, and the formula (2) as an index of the painting property and the formula (4) as an index of the productivity are not satisfied. The welding wire of Example 27 has been broken during the manufacturing process. In addition, Example 27 becomes not qualified with respect to the electrodeposition painting property.

[0249] On the other hand, in the case of Examples in which the chemical components are appropriate and the formulae (1) to (4) are satisfied, all of the productivity, the gap weldability and the painting property are good. In addition, in the case of Examples in which the formula (6) as an index of the spatter generation amount is satisfied, the spatter adhesion amount is suppressed to a very low level.

[0250] (Experiment 2)

[0251] Various solid core welding wires are manufactured by a manufacturing method having the following steps: a step of subjecting a wire rod to primary drawing to obtain a primary drawn welding wire; a step of annealing the primary drawn welding wire; and a step of subjecting the primary drawn welding wire to secondary drawing to obtain a solid core welding wire. At the annealing of the primary drawn welding wire, the dew point of the annealing atmosphere is set to a range of -10 to +10°C. The composition of the solid core welding wire, the annealing temperature, the annealing time, and the area ratio of the secondary drawn welding wire to the primary drawn welding wire are set as shown in Table 6.

[0252] Then, H1 (Vickers hardness measured at a position at a depth of 0.05 mm from the surface of the solid core welding wire) and H2 (average of Vickers hardnesses measured at positions at depths of 0.25 mm and 0.35 mm from the surface) of these solid core welding wires are measured. H2 and H2-H1 are recorded in Table 6.

[0253] Further, welding tests are performed using these solid core welding wires, and the spatter adhesion amount is investigated. The method of measuring the spatter adhesion amount is set to be the same as in Experiment 1.

[0254] [Table 6]

[0255]

[0256] "Area ratio" is the area ratio of the secondary drawn welding wire to the primary drawn welding wire

[0257] In the case of Example B2, the product of the annealing temperature and the annealing time is large. Due to this, H2 of Example B2 becomes small. In the welding test of Example B2, the spatter adhesion amount is the same level as that of the conventional solid core welding wire.

[0258] In the case of Example B3, the product of the annealing temperature and the annealing time is small. Due to this, H2-H1 of Example B3 becomes small. In the welding test of Example B3, the spatter adhesion amount is the same level as that of the conventional solid core welding wire.

[0259] In the case of Example B7, H2-H1 of Example B7 becomes small due to the small area ratio of the secondary drawn welding wire to the primary drawn welding wire. In the welding test of Example B7, the spatter adhesion amount is the same level as that of the conventional solid core welding wire.

[0260] On the other hand, in the welding test of the solid core welding wire in which H2 and H2-H1 are appropriate, the spatter adhesion amount is significantly improved compared to the conventional solid core welding wire.

[0261] Explanation of symbols

[0262] 1 Welded metal

[0263] 2 Steel plate

[0264] 3 Spacer

[0265] 4 solid wire

[0266] 5 droplet

[0267] S gap

[0268] A undercuts

Claims

1. A solid welding wire for gas shielded arc welding, characterized in that in terms of mass% relative to the total mass of the solid wire: C：0.04～0.12％、 Si: 0.13 to 0.28%, Mn: 1.4 to 2.3%, Ti: 0.13 to 0.25%, Al：0.001～0.050％、 Cr：0～3.00％、 Ni: 0 to 3.00%, P: 0.020% or less, S: 0.015% or less, N: 0.0060% or less, Mo: 0 to 0.5%, B：0～0.0100％、 Cu: 0 to 0.50%, Nb: 0 to 0.30%, V：0～0.5％、 Zr：0～0.20％、 Mg: 0 to 0.050%, As: 0 to 0.020%, Sn: 0 to 0.100%, Sb: 0 to 0.10%, and remainder: iron and impurities, satisfy the following (1) formula, (2) formula, (3) formula, (4) formula, and (5) formula, Si x Mn ≤ 0.60 (1) formula (Si + Mn / 5) / (Ti + Al) ≤ 4.0 (2) formula 1.00 ≤ Si + 0.5 x (Mn + Cr) + 0.3 x Ni (3) formula 0.30 ≤ C + Mn / 6 + Si / 24 + Ni / 40 + Cr / 5 + Mo / 4 + V / 14 ≤ 0.55 (4) formula 0 ≤ Cr + Ni ≤ 3.00 (5) formula wherein the element symbols in the (1) formula, the (2) formula, the (3) formula, the (4) formula, and the (5) formula are contents of respective elements in terms of mass% relative to the total mass of the solid wire.

2. The gas shielded arc welding solid wire according to claim 1, characterized by 0.16 ≤ C x (5 x Si + Mn) ≤ 0.35 (6) formula in terms of mass% relative to the total mass of the solid wire.

3. The gas shielded arc welding solid wire according to claim 1 or 2, characterized in that, contains one or more selected from Al: 0.010 to 0.050%, Cr: 0.10 to 1.50%, Ni: 0.10 to 3.00%, and B: 0.0030 to 0.0100% in terms of mass% relative to the total mass of the solid wire.

4. The gas shielded arc welding solid wire according to any one of claims 1 to 3, characterized in that, the hardness measured in the cross section of the solid wire satisfies the following (7) formula and (8) formula, H2 ≥ 250 (7) formula H2 - H1 ≥ 40 (8) formula wherein the symbol H1 in the (8) formula is a Vickers hardness measured at a position at a depth of 0.05 mm from the surface of the solid wire, and the symbol H2 in the (7) formula and the (8) formula is an average value of Vickers hardnesses measured at positions at depths of 0.25 mm and 0.35 mm from the surface.

5. The gas shielded arc welding solid wire according to any one of claims 1 to 4, characterized in that, Si: 0.13 to 0.19% in terms of mass% relative to the total mass of the solid wire.

6. The gas shielded arc welding solid wire according to any one of claims 1 to 5, characterized in that, Cr: 0.15 to 3.00% in terms of mass% relative to the total mass of the solid wire.

7. The gas shielded arc welding solid wire according to any one of claims 1 to 5, characterized in that, Cr: 0% or more and less than 0.50% in terms of mass% relative to the total mass of the solid wire.

8. The gas shielded arc welding solid wire according to any one of claims 1 to 7, characterized in that, Ni: 0 to 0.45% in terms of mass% relative to the total mass of the solid wire.

9. The gas shielded arc welding solid wire according to any one of claims 1 to 8, characterized in that, 0.05 ≤ Cr + Ni ≤ 3.00 (9) formula in terms of mass% relative to the total mass of the solid wire.

10. The gas shielded arc welding solid wire according to any one of claims 1 to 9, characterized in that, 0.8 to 1.4 mm in diameter.

11. A method for manufacturing a welded joint, comprising a step of performing gas shielded arc welding on a steel sheet using the solid core welding wire for gas shielded arc welding according to any one of claims 1 to 10.

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