JP2009255142A - Solid wire and manufacturing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid wire as a welding wire that can reduce production of spatters during arc welding and that has excellent weldability, and also to provide the manufacturing method of the solid wire. <P>SOLUTION: The solid wire 1 is composed of element wires 1a, 1b made of steel alloy, is provided with an alkaline metal impregnated part 3 in which two or more kinds of alkaline metals are impregnated near the surface of the element wires, and is characterized in that the total concentration of the alkaline metals in the alkaline metal impregnated part 3 is ≥1.5 mass ppm relative to the total mass of the solid wire 1. Also, the manufacturing method of the solid wire 1 includes an element wire making process, a coating process, an annealing process and a wire drawing process, wherein the melting point of the mixture of the alkaline metal carbonate in the coating process is below the annealing temperature in the annealing process. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solid wire used for arc welding of automobile parts and the like, and a manufacturing method thereof.

  Conventionally, in arc welding using a solid wire (welding wire), there is a problem that welding workability deteriorates due to generation of spatter. And it became clear that an alkali metal is effective in reducing generation | occurrence | production of a sputter | spatter, and the welding wire of the various structures which contained the alkali metal in the wire is examined.

  For example, Patent Document 1 describes a welding wire in which an alkali metal (one or two of Na and K) is cast into a drawn piece and added to the wire. Patent Document 2 or Patent Document 3 describes a welding wire in which a groove or a crack is formed on the surface of the wire and an alkali metal (a K compound or a lubricant containing K) is held in the groove or the crack. Patent Document 4 describes a welding wire in which an alkali metal (Na) is held during copper plating applied to the wire surface. Patent Document 5 or Patent Document 6 describes a welding wire in which a surface lubricant containing an alkali metal (K) or a surface treatment oil containing an alkali metal compound is applied to the wire surface. In Patent Document 7 or Patent Document 8, a steel salt wire is coated with a potassium salt (aqueous solution), and thereafter annealed and drawn to perform a welding process in which a predetermined amount of potassium is impregnated in the steel wire. Wires are described. In Patent Document 7, potassium carbonate and potassium hydroxide are described as potassium salts.

Japanese Patent Laid-Open No. 4-118195 JP-A-7-223087 Japanese Patent Laid-Open No. 7-47490 JP 2006-326680 A JP 2006-102799 A JP 2006-15403 A JP 2000-246485 A JP 2004-195542 A

  However, in the welding wire disclosed in Patent Document 1, when an industrially large melting furnace is used, the yield of the added stretch piece (alkali metal) cannot be managed, so that the control of the alkali metal concentration is not possible. Is possible. In addition, since the alkali metal has a very high activity, the stretched piece (alkane metal) is oxidized at the time of dissolution, and the amount of the alkali metal added to the wire becomes small, so that a sufficient amount of the alkali metal is added to the wire. It is industrially difficult to add an alkali metal. Therefore, the welding wire of Patent Document 1 cannot reduce the occurrence of spatter in arc welding, and cannot solve the problem of deterioration in welding workability.

  In the welding wire of Patent Document 2 or Patent Document 3, when the wire is fed, the alkali metal compound held in the groove or in the crack is dropped and clogging inside the welding electrode tip, conduit tube, etc. Cause. Moreover, a sufficient amount of alkali metal cannot be retained on the wire surface due to the dropping of the alkali metal compound. Therefore, in the welding wire of patent document 2 or patent document 3, in arc welding, generation | occurrence | production of a spatter cannot be reduced and the problem that welding workability deteriorates cannot be solved.

  In the welding wire of Patent Document 4, it is difficult to industrially implement the plating bath because it is very complicated to stably add a sufficient amount of alkali metal. Therefore, the welding wire of Patent Document 4 cannot reduce the occurrence of spatter in arc welding and cannot solve the problem of deterioration in welding workability.

  In the welding wire of Patent Document 5 or Patent Document 6, the surface lubricant or the surface treatment oil drops off during wire feeding, causing clogging inside the welding tip, conduit tube, and the like. Moreover, a sufficient amount of alkali metal cannot be held on the wire surface due to the removal of the surface lubricant or the surface treatment oil. Therefore, in the welding wire of patent document 5 or patent document 6, generation | occurrence | production of spatter cannot be reduced in arc welding, but the problem that welding workability | operativity deteriorates cannot be solved.

  The welding wire disclosed in Patent Document 7 or Patent Document 8 has the following problems. FIG. 5 is an explanatory view schematically showing a process of forming an alkali metal impregnated portion in the production of a conventional welding wire (solid wire), and FIG. 6 is an SEM photograph showing a cross-sectional structure of the conventional solid wire. is there.

As shown in FIG. 5, the potassium salt (aqueous solution) applied to the surface of the steel wire 11 a is decomposed by the heat during annealing, and the fine solid potassium salt 12 (for example, potassium carbonate K ₂ CO ₃ ). It becomes. Since the contact between the fine solid potassium salt 12 and the surface of the steel strand 11a is partial (the contact area is small), the alkali metal impregnated portion 13 formed in the steel strand 11a is also small. As a result, it becomes difficult to keep the alkali metal (K) in the wire 11 at a high concentration.

Further, since the contact between the potassium salt 12 and the steel wire 11a becomes partial, the atmosphere gas (O ₂ ) and the steel wire at the time of annealing are in direct contact (reaction), and the surface of the steel wire 11a is impregnated with potassium. Excess grain boundary oxidation occurs in the vicinity (see FIG. 6). The grain boundary oxidized crystal grains fall off during wire feeding, causing clogging inside welding electrode tips, conduit tubes, etc. (not shown), and covering the wire surface. Also adversely affects the plating adhesion of Cu and the like. Furthermore, the amount of potassium retained in the wire 11 is reduced due to the drop of crystal grains.
Therefore, in the welding wire of patent document 7 or patent document 8, generation | occurrence | production of spatter cannot be reduced in arc welding, but the problem that welding workability deteriorates cannot be solved.

  Note that potassium hydroxide has a lower melting point than potassium carbonate and does not decompose during the annealing process. However, since potassium hydroxide is a strong alkali, its handling is complicated, and adverse effects such as corrosion on the annealing equipment occur.

  Therefore, the present invention has been devised to solve such a problem, and its purpose is to reduce the occurrence of spatter during arc welding and to provide a solid wire as a welding wire having excellent welding workability and It is in providing the manufacturing method.

  In order to solve the above-mentioned problem, a solid wire according to claim 1 is made of a steel alloy strand, and has a solid impregnated portion in which two or more kinds of alkali metals are impregnated near the surface of the strand. It is a wire, Comprising: The total density | concentration of the alkali metal in the said alkali metal impregnation part is 1.5 mass ppm or more with respect to the total mass of the said solid wire, It is characterized by the above-mentioned.

  According to the above configuration, the alkali metal impregnation portion impregnated in the alkali metal impregnated portion has two or more types of alkali metal so that the impregnation of the alkali metal into the strands wets and spreads on the surface of the strands. The molten salt layer (liquid state) is used. As a result, the contact area between the alkali metal and the surface of the wire increases, the amount of alkali metal impregnated in the wire increases, and 1.5 mass ppm or more sufficient to suppress the occurrence of spatter during arc welding A high concentration alkali metal is impregnated and held in a strand (solid wire). Moreover, the impregnated alkali metal of 1.5 mass ppm or more reduces the surface oxide of the strand, and forms an iron single layer on the outermost surface of the strand. This iron single layer can be made such that the surface of the wire before plating is made of only metal, and is not recognized in conventional wires. And formation of this iron single layer prevents plating adhesion and excessive grain boundary oxidation, prevents dropping of crystal grains containing alkali metal, and provides stable alkali metal impregnation.

  The manufacturing method of the solid wire which concerns on Claim 2 uses the strand produced from the steel alloy material, the application | coating process which apply | coats the mixture of two or more types of alkali metal carbonates on the surface of the said strand, The said mixture An annealing process in which softening annealing is performed on an element-coated wire at an annealing temperature of 630 to 1000 ° C., and a wire that is softened and annealed in the annealing process is subjected to one or more drawing processes to produce a wire And the melting point of the mixture in the coating step is lower than the annealing temperature in the annealing step.

According to the said procedure, an application | coating process is included, In the application | coating process, the melting | fusing point of the mixture becomes low by apply | coating the mixture of two or more types of alkali metal carbonates to the surface of a strand. And including an annealing process, by making the melting point of the mixture below the annealing temperature of the annealing process, in the annealing process, the mixture applied to the surface of the strand is melted by soft annealing in the annealing process, and in a liquid state A molten salt layer is formed. By forming the molten salt layer in the liquid state, the contact area between the alkali metal and the surface of the strand increases, and the amount of alkali metal impregnated in the strand increases. As a result, a sufficient amount of alkali metal is held in the strand to suppress the occurrence of sputtering. In addition, the molten salt layer blocks direct contact between the surface of the wire and the atmospheric gas (O ₂ ), thereby suppressing excessive grain boundary oxidation and preventing crystal grains from falling off and being held in the wire. Prevents alkali metal from dropping (reducing). Furthermore, the sufficient amount of alkali metal held in the strand reduces the surface oxide of the strand and forms an iron single layer on the outermost surface of the strand.

  According to a third aspect of the present invention, there is provided a first method of producing a solid wire having a predetermined diameter by subjecting the wire to one or more wire drawing using a wire produced from a steel alloy material. A wire processing step, a coating step of applying a mixture of two or more kinds of alkali metal carbonates to the surface of the wire produced in the first wire drawing step, and 630 to 1000 on the wire coated with the mixture. An annealing step for softening annealing at an annealing temperature of ° C., and a second wire drawing step for producing a wire by subjecting the wire softened and annealed in the annealing step to wire drawing at least once, and The melting point of the mixture in the coating step is less than the annealing temperature in the annealing step.

  According to the said procedure, the wire-drawing process by which the wire-drawing process which diameter-reduces an element wire is performed is performed by 2 processes by including a 1st wire drawing process and a 2nd wire-drawing process. Thus, the diameter reduction from the wire to the wire is performed efficiently. Further, the actions of the coating step and the annealing step are the same as in the manufacturing method of claim 2.

  According to the solid wire according to the present invention, since the alkali metal impregnated in the alkali metal impregnated portion is two or more kinds, the amount of the alkali metal impregnated in the strand increases, and 1.5 mass ppm in the wire. Since the above alkali metals can be impregnated and retained, the occurrence of spatter during arc welding can be reduced, and excellent welding workability can be achieved. In addition, when a plating layer is provided on the wire surface, the iron single layer on the outermost surface of the wire has excellent plating adhesion.

  According to the method for producing a solid wire according to the present invention, the contact area of the alkali metal can be increased, excessive grain boundary oxidation can be suppressed, and a sufficient amount of alkali metal can be impregnated in the wire. The solid wire having excellent welding workability can be manufactured. Moreover, the solid wire which has the outstanding plating adhesiveness can be manufactured by forming an iron single layer in the outermost surface of a strand. Furthermore, a solid wire can be easily manufactured.

  The solid wire according to the present invention will be described in detail with reference to FIGS. FIG. 1 shows the configuration of a solid wire, where (a) is a cross-sectional view along the axial direction, (b) is a cross-sectional view along line AA in (a), and FIG. It is a SEM photograph which shows a section organization.

<Solid wire>
As shown in FIG. 1 and FIG. 2, a solid wire (hereinafter also referred to as a wire) 1 is composed of strands 1a and 1b, and an alkali metal (for example, K + Na + Li) near the surface of the strands 1a and 1b. Has an alkali metal impregnated portion 3 impregnated with. Although not shown, the wire 1 may have a plating layer made of Cu or the like on the outermost surface, that is, the alkali metal impregnated portion 3.

(Elementary wire)
If the strands 1a and 1b consist of steel alloys, the composition will not be specifically limited, C: 0.01-0.12 mass%, Si: 0.2-1.2 mass%, Mn: It is preferable that 0.5-2.5 mass%, P: 0.03 mass% or less, S: 0.001-0.03 mass% are contained, and the remainder is Fe and an unavoidable impurity.

  The C, Si, Mn, or S is added for the purpose of further reducing the occurrence of spatter in arc welding. The reasons for limiting the numerical range of C, Si, Mn or S are as follows. When the content of C, Si, Mn or S is less than the lower limit value, the surface tension of the droplets becomes small, and the effect of reducing the occurrence of sputtering tends to be small. In addition, if the content of C, Si, Mn or S exceeds the upper limit, the surface tension of the droplet increases, the droplet at the tip of the wire is repelled by the arc force, and sputtering is likely to scatter, Sputtering tends to increase. Moreover, when content of P exceeds an upper limit, the crack resistance of a welding part (welded metal) will deteriorate easily. Note that if the S content exceeds the upper limit, the occurrence of sputtering tends to increase, and crack resistance tends to deteriorate like P.

  Inevitable impurities may include O, N, etc., but they are allowed to be contained within a range not impeding the effects of the present invention, O: 0.02% by mass or less, N: 0.00. 01 mass% or less is preferable.

  The strands 1a and 1b further preferably contain Ti: 0.30% by mass or less in addition to the above composition. Ti is added for the purpose of further reducing the occurrence of spatter in arc welding. If the content exceeds 0.30% by mass, the surface tension of the droplet increases and the wire tip melts. The droplets are repelled by the arc force, so that the spatter is likely to scatter and the occurrence of spatter tends to increase. Ti has the effect of stabilizing the arc in a wide current range (200 to 350 A) together with low sputtering.

(Alkali metal impregnation part)
The alkali metal impregnated part 3 is a region formed in the vicinity of the surface of the strands 1a and 1b and impregnated with two or more kinds of alkali metals. Here, as the alkali metal, K, Na, or Li is preferable in consideration of a high impregnation rate into the strands 1a and 1b or an industrially inexpensive point. Moreover, although the depth of the alkali metal impregnation part 3 is based also on a wire diameter (elementary wire diameter), it is 5-30 micrometers, for example.

  Here, since there are two or more kinds of alkali metals impregnated in the alkali metal impregnated portion 3, in the production of the wire 1 described later, impregnation of the alkali metal into the strands 1a and 1b is performed by the strands 1a and 1b. This is performed by the molten salt layer 2 (liquid state) of the alkali metal salt mixture having a low melting point wetted and spread on the surface (see FIG. 4). This increases the contact area between the alkali metal and the surfaces of the strands 1a and 1b, increases the amount of alkali metal impregnated in the strands 1a and 1b, and is sufficient to suppress the occurrence of spatter during arc welding. A high concentration of alkali metal is impregnated and held in the strands 1a and 1b (wire 1).

  The total concentration of alkali metals in the alkali metal impregnated portion 3 needs to be 1.5 mass ppm or more with respect to the total mass of the wire 1. Preferably it is 5 mass ppm or more, More preferably, it is 10 mass ppm or more. If the total concentration is less than 1.5 mass ppm, the generation of spatter cannot be reduced. The total concentration of alkali metals is preferably a concentration measured after the wire 1 is straightened. In other words, the total concentration of alkali metal is measured after the straightening process corresponding to the wire feeding to the inside of the conduit tube (not shown), so that it does not fall off during the wire feeding. It is possible to accurately measure the total concentration of alkali metals held in the substrate.

  Moreover, as shown in FIG. 2, when the total concentration of alkali metals is 1.5 ppm by mass or more, the surface oxides of the strands 1a and 1b are reduced, and iron is formed on the outermost surfaces of the strands 1a and 1b. A single layer is formed. This iron single layer can suppress deterioration of the adhesion of the plating layer due to the surface oxide when a plating layer made of Cu or the like is provided on the strands 1a and 1b (wire 1).

<Manufacturing method of solid wire>
Next, a method for manufacturing a solid wire according to the present invention will be described in detail with reference to FIGS. 3 (a), 3 (b), and 4. FIG. FIGS. 3A and 3B are process diagrams showing a method of manufacturing a solid wire, and FIG. 4 is an explanatory view schematically showing a process in which an alkali metal impregnated portion is formed in the manufacture of the solid wire. The wire configuration will be described with reference to FIGS. 1A, 1B, and 2. FIG.

  As shown to Fig.3 (a), the 1st manufacturing method of the solid wire 1 includes application | coating process S1, annealing process S2, and wire drawing process S3. Hereinafter, each step will be described.

(Coating process: S1)
The application step S1 is a step of applying a mixture of two or more types of alkali metal carbonates to the surface of the strand 1a using the strand 1a made from a steel alloy material.

  The steel alloy material has a shape such as a billet, and is manufactured by melting molten steel having the above composition by a normal melting method using a converter, an electric furnace, or the like, and casting the molten steel. And the strand 1a of a predetermined diameter (for example, 5-9 mm) is produced by performing hot rolling and then cold rolling as needed to a steel alloy material. Moreover, you may procure the strand 1a of a predetermined diameter by purchase etc. as needed.

  Furthermore, two or more types of alkali metal carbonates are mixed so that the melting point of the mixture is lower than the annealing temperature in the next step (annealing step S2). If the melting point is equal to or higher than the annealing temperature, the molten salt layer 2 (see FIG. 4) of the mixture is not formed on the surface of the strand 1a in the annealing step S2, and the solid state alkali metal carbonate ( For example, since the potassium salt 12 (see FIG. 5) is formed, the amount of alkali metal impregnated in the strand 1a is reduced.

  Application of the alkali metal carbonate mixture is performed by conventionally known brush coating, spray coating, dip coating, or the like. The mixture of the present invention includes an alkali metal carbonate aqueous solution in addition to a mixture obtained by directly mixing two or more kinds of alkali carbonates.

(Annealing process: S2)
The annealing step S2 is a step in which softening annealing is performed at an annealing temperature of 630 to 1000 ° C. on the strand 1a coated with a mixture of two or more kinds of alkali metal carbonates in the coating step S1. Here, when the annealing temperature is less than 630 ° C., the wire 1a is not softened, and the wire drawing in the next step (the wire drawing step S3) becomes difficult. On the other hand, if the annealing temperature exceeds 1000 ° C., the softened state is saturated and it is not economical. As for the annealing time, the time required for the wire 1a to be sufficiently softened is appropriately set according to the annealing temperature. For example, when the annealing temperature is 830 ° C., the annealing time is 30 minutes.

In the annealing step S2, as shown in FIG. 4, a mixture of two or more kinds of alkali metal carbonates is melted to form a molten salt layer 2 in a liquid state (for example, K ₂ CO ₃ + Na ₂ CO ₃ + Li ₂ CO ₃ ). And the surface of the element wire 1a is spread. Thereby, a wide contact area between the alkali metal salt and the surface of the strand 1a is ensured. Then, the alkali metal is effectively impregnated in the wire 1a, the wide alkali metal impregnated portion 3 is formed, and a high concentration of alkali metal (for example, K + Na + Li) can be held in the wire 1 (wire 1a). it can. In addition, the molten salt layer 2 that has spread out suppresses excessive intergranular oxidation (see FIG. 6) that has occurred in the conventional wire by blocking the contact between the atmospheric gas (O ₂ ) and the wire 1a. In addition, since the crystal grains near the surface do not fall off, the alkali metal impregnated at a high concentration can be prevented from dropping (reducing). As a result, in arc welding, a high concentration of alkali metal can be held in the wire even after the wire is fed, so that the occurrence of spatter can be reduced and welding workability can be improved.

  Further, as shown in FIG. 2, the high concentration alkali metal held in the alkali metal impregnated portion 3 reduces the surface oxide formed on the strand 1a, and an iron single layer on the outermost surface of the strand 1a. Form. By forming the iron single layer, when a plating layer (not shown) made of Cu or the like is provided on the surface of the wire (element wire 1a), the adhesion of the plating layer can be improved.

(Wire drawing process: S3)
The wire drawing step S3 is a step of producing the wire 1 by performing the wire drawing process one or more times on the strand 1a softened and annealed in the annealing step S2. That is, this is a step of reducing the wire diameter (5 to 9 mm) to a predetermined wire diameter (1 to 8 mm). The number of wire drawing processes is appropriately set according to the wire diameter and the wire diameter. The wire drawing is performed by a conventionally known processing method using a dry or wet hole die.

  As shown in FIG.3 (b), the 2nd manufacturing method of the solid wire which concerns on this invention is 1st wire drawing process S1a, application | coating process S2a, annealing process S3a, and 2nd wire drawing process S4a. Is included. The first manufacturing method includes the coating step S1 and the annealing step S2 before the wire drawing step S3, whereas the second manufacturing method includes two wire drawing steps (first step). Between the wire drawing step S1a and the second wire drawing step S4a), the coating step S2a and the annealing step S3a are included.

(First wire drawing process: S1a)
The first wire drawing step S1a is a step in which the wire 1a made of a steel alloy material is subjected to wire drawing work one or more times to produce a wire 1b having a predetermined diameter. That is, it is a step of reducing the wire diameter from 5 to 9 mm to 2 to 3 mm, for example. Further, the diameter reduction rate and the number of wire drawing processes are appropriately set in consideration of work efficiency in manufacturing the wire 1. The wire drawing is performed by a conventionally known processing method using a dry or wet hole die. Moreover, the manufacturing method of the strand 1a is the same as the said 1st manufacturing method.

(Coating process: S2a), (Annealing process S3a)
In the coating step S2a, the strand 1b produced in the first wire drawing step S1a is used as the strand for coating the mixture of alkali metal carbonates. In the annealing step S3a, the strand coated with the mixture As the first manufacturing method (application step S1, annealing step S2) except that the wire 1b is used, the description is omitted.

(Second wire drawing process: S4a)
In this step, the wire 1 is produced by subjecting the wire 1b softened and annealed in the annealing step S3a to one or more wire drawing processes. That is, this is a step of reducing the wire diameter (2 to 3 mm) to a predetermined wire diameter (1 to 2 mm). Further, the number of wire drawing processes is appropriately set according to the wire diameter and the wire diameter. The wire drawing is performed by a conventionally known processing method using a dry or wet hole die.

Next, examples of the present invention will be described.
(Example (No. 1-12))
Steel alloy (C: 0.04 mass%, Si: 0.8 mass%, Mn: 1.2 mass%, P: 0.010 mass%, S: 0.010 mass%, Ti: 0.24 mass% The balance was Fe and inevitable impurities), and a strand for solid wire having a diameter of 5.5 mm was prepared by melting, casting, and hot rolling. And the wire was drawn to φ2.4 mm with a dry hole die (drawing process). Next, a mixture of two or more kinds of alkane metal carbonates mixed in the mixing amount shown in Table 1 was applied to the drawn wire (application process). And the softening annealing was performed to the strand with which the mixture was apply | coated 830 degreeC x 30 minutes (annealing process). Next, the soft annealed strand was drawn to φ1.2 mm with a dry hole die to produce a solid wire (drawing step).

  Here, as a mixed state of the alkali metal carbonate, when two or more kinds of alkali metal carbonates are directly mixed in a solid state (Examples (No. 1, 3, 5, 7, 9, 11)), and Two or more kinds of alkali metal carbonates were mixed in an aqueous solution state of about 5% by mass (Examples (No. 2, 4, 6, 8, 10, 12)). Moreover, as an application method, when alkali metal carbonate was directly mixed in a solid state, it was heated to form a molten salt, and a strand was immersed in the molten salt. When the alkali metal carbonate was mixed in an aqueous solution state, a strand was immersed in the aqueous solution.

(Comparative example (No. 13-18))
The comparative example (No. 13-16) produced the solid wire like Example (No. 1 or No. 2) except using one type of alkali metal carbonate. Moreover, the comparative example (No. 17-18) produced the solid wire like Example (No. 7 or No. 8) except performing softening annealing of 600 degreeC x 30 minutes.

  About the produced solid wire (Example (No. 1-12), comparative example (No. 13-18)), the correction process was performed on the following conditions, and the chemical analysis of the alkali metal density | concentration was performed after that. The results are shown in Table 1. The alkali metal concentration was calculated as the mass concentration of alkali metal with respect to the entire mass of the solid wire. The results are shown in Table 1.

(Correction processing conditions)
The solid wire was bent along a roller having a radius of 30 mm, and then returned (bending) was repeated four times.

  Moreover, about the solid wire (Example (No. 1-12) and Comparative Example (No. 13-18) after straightening, cross-sectional SEM observation was performed and the impregnation condition of the alkali metal was confirmed. About an example (No. 1), a SEM photograph is shown in FIG.

  Next, arc welding was performed on the solid wires (Examples (No. 1 to 12) and Comparative Examples (No. 13 to 18)) after straightening under the following welding conditions, and the amount of spatter generated was evaluated. As an evaluation method, spatter scattered around the arc point was observed with the naked eye, and the amount of the spatter was sensory evaluated. The results are shown in Table 1. In Table 1, a sample with a small amount of spatter generation was evaluated as (◯), and a sample with a large amount of spatter generation was evaluated as (x).

(Welding conditions)
-Test steel sheet: JIS G 3106 SM490B
Shield gas: 100% CO ₂ (flow rate 20 liter / min)
・ Welding current: 280A
・ Welding voltage: 32V
・ Welding speed: 40 cm / min
・ Wire protrusion length: 25mm
・ Welding polarity: DCEP
-Welding posture: downward bead-on-plate welding

  From the above results, since the solid wires of Examples (No. 1 to 12) used a mixture of two or more types of alkali metal carbonates, the melting point of the mixture was less than the annealing temperature, and the surface of the solid wire was near the SEM photograph. The alkali metal impregnated portion was confirmed, and the total concentration of alkali metals in the alkali metal impregnated portion was 1.5 mass ppm or more. As a result, when arc welding was performed using the solid wires of Examples (Nos. 1 to 12), the amount of spatter generated was small.

  Specifically, the solid wires of the examples (Nos. 1 to 8) have a total alkali metal concentration of 10 mass ppm or more, so that no large-scale spatter is generated even when welding is performed for 5 minutes or more. It was. In the solid wires of the examples (Nos. 9 to 10), the total concentration of alkali metals was 5 ppm by mass or more and less than 10 ppm by mass. In the solid wires of the examples (No. 11 to 12), the total concentration of alkali metals is 1.5 mass ppm or more and less than 5 mass ppm. The outbreak remained.

  On the other hand, since the solid wire of the comparative example (No. 13-16) used one kind of alkali metal carbonate, melting | fusing point of alkali metal carbonate became more than an annealing temperature, and the surface vicinity of a solid wire is shown by a SEM photograph. Although an alkali metal impregnated part was confirmed, the alkali metal concentration was less than 1.5 ppm by mass. As a result, the solid wires of the comparative examples (Nos. 13 to 16) were sputtered with 10 or more grains in 1 minute arc welding. In the solid wires of the comparative examples (Nos. 13 to 16), excessive grain boundary oxidation occurred compared to the examples, and the surface crystal grains containing the alkali metal dropped out by the straightening process, so the total concentration of the alkali metal was lowered. It was.

  Moreover, although the solid wire of the comparative example (No. 17-18) used the mixture of two types of alkali metal carbonates, since the annealing temperature was made into less than a lower limit, melting | fusing point of a mixture became more than annealing temperature, and SEM photograph As a result, an alkali metal impregnated portion was confirmed in the vicinity of the surface of the solid wire, but the concentration of the alkali metal was less than 1.5 ppm by mass. As a result, the solid wires of the comparative examples (Nos. 17 to 18) were sputtered with 10 or more grains by arc welding for 1 minute. Moreover, since the solid wire of the comparative examples (Nos. 17 to 18) had a low annealing temperature, a part of the wire was broken during the wire drawing process. The arc welding was performed at a portion where no disconnection occurred.

The structure of the solid wire which concerns on this invention is shown, (a) is sectional drawing along an axial direction, (b) is sectional drawing along the AA of (a). It is a SEM photograph which shows the section organization of the solid wire concerning the present invention. (A), (b) is process drawing which shows the manufacturing method of the solid wire which concerns on this invention. It is explanatory drawing which shows typically the process in which an alkali metal impregnation part is formed in manufacture of the solid wire which concerns on this invention. It is explanatory drawing which shows typically the process in which an alkali metal impregnation part is formed in manufacture of the conventional wire for welding (solid wire). It is a SEM photograph which shows the cross-sectional structure | tissue of the conventional solid wire.

Explanation of symbols

1 Solid wire (wire)
DESCRIPTION OF SYMBOLS 1a, 1b Wire 2 Molten salt layer 3 Alkali metal impregnation part S1 Application | coating process S2 Annealing process S3 Wire drawing process S1a 1st wire drawing process S2a Application | coating process S3a Annealing process S4a 2nd wire drawing process

Claims (3)

A solid wire comprising a strand made of steel alloy and having an alkali metal impregnated portion impregnated with two or more kinds of alkali metals in the vicinity of the surface in the strand,
The solid wire, wherein a total concentration of alkali metals in the alkali metal impregnated portion is 1.5 mass ppm or more with respect to a total mass of the solid wires. An application step of applying a mixture of two or more types of alkali metal carbonates to the surface of the element wire using an element wire made from a steel alloy material;
An annealing step of subjecting the wire coated with the mixture to soft annealing at an annealing temperature of 630 to 1000 ° C .;
A wire drawing step for producing a wire by subjecting the wire softened and annealed in the annealing step to wire drawing at least once, and
The solid wire manufacturing method, wherein a melting point of the mixture in the coating step is lower than an annealing temperature in the annealing step. A first wire drawing step of producing a wire having a predetermined diameter by subjecting the wire to at least one wire drawing using a wire produced from a steel alloy material;
An application step of applying a mixture of two or more kinds of alkali metal carbonates to the surface of the wire produced in the first wire drawing step;
An annealing step of subjecting the wire coated with the mixture to soft annealing at an annealing temperature of 630 to 1000 ° C .;
A second wire drawing step of producing a wire by subjecting the wire softened and annealed in the annealing step to wire drawing at least once, and
The solid wire manufacturing method, wherein a melting point of the mixture in the coating step is lower than an annealing temperature in the annealing step.