JP2005021983A - Titanium-based wire rod for forming molten metal and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a titanium-based wire rod for forming molten metal which is excellent in both feeding ability and arc stability. <P>SOLUTION: The titanium-based wire rod 301 for forming the molten metal is composed of a rod stock 3 of titanium-based metal. The longitudinal tensile strength of the wire rod is in a range between Smin and Smax, wherein Smin=-230Dw+850 in MPa and Smax=-620Dw+2,000 in MPa. A titanium-based oxide film of 1μm or more and 5μm or less in thickness is formed on the surface of the rod stock 3. The rod stock 3 on which a titanium-based oxide film 2 is formed is then thinned together with the titanium-based oxide film 2 by a cold wire drawing process. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a Ti-based wire used for forming a molten metal in welding, thermal spraying, or the like.

  When welding Ti-based metal members made of Ti metal or Ti alloy, arc welding is performed by using an industrial Ti-based wire and covering the welding site with an inert gas to prevent oxidation of Ti, which is an active metal. Performed shielded arc welding is employed. For example, in MIG welding (Metal Inert Gas Arc Welding), as shown in FIG. 8, a Ti wire 201 for welding and a base material WP made of pure titanium or titanium alloy in an inert gas IG atmosphere such as argon or helium. An arc AR is generated between the two. Then, the tip of the wire 201 is fed into the arc AR by the feed roller 202 and welded while being melted. Reference numeral 205 denotes a gas nozzle (torch) that ejects an inert gas IG from the distal end, and includes a flexible conduit tube 204 on the proximal end side. Reference numeral 206 denotes an electrode tip (contact tip) that is fixed to the torch 205 and holds the wire 201 and supplies current to the wire 201, WM is a weld bead, and MP is a molten pool. According to MIG welding, there is an advantage that not only the efficiency is increased, but the melting is deepened and the occurrence of poor welding is suppressed by improving the melting energy, and the tip of the torch 205 is reduced in size to facilitate welding in a narrow place. is there.

  On the other hand, a Ti-based metal coating layer is formed by thermal spraying for the purpose of corrosion-resistant coating of large members. In the field of this thermal spraying, a thermal spray layer is formed by a thermal spraying method, for example, an arc thermal spraying method, using a Ti-based wire similar to the above welding. In the arc spraying method, two Ti-based wires are fed in parallel to a holder for energization, and an arc discharge gap is formed between the tips of the wires to create a molten metal, which is made of an inert gas such as nitrogen or argon, or This is a method in which a sprayed layer is deposited on the surface of an object to be processed by jetting air as a medium. The Ti-based wire is fed to the thermal spray gun through a conduit tube as in the case of welding.

  By the way, in recent years, in order to improve the efficiency of the Ti welding process and shorten the delivery time of the welding work, the feeding speed of the wire 201 tends to be further increased. In this case, when the frictional force between the surface of the wire 201 and the conduit tube 204 is large, the wire 201 is not smoothly fed, and in the worst case, the wire 201 is clogged or buckled in the conduit tube 204. There is a fear.

  In particular, in the case of a conventional welding Ti-based wire, the surface of the wire is mechanically or chemically polished to give a metallic luster finish. There is a problem that it is rough and inferior in feedability. In addition, the wire having a metallic gloss appearance is not as good as the arc stability during welding, and in MIG welding using an automatic welder, the arc moves finely in search of a stable point. There is a problem that a good bead shape cannot be obtained. This seems to be related to the fact that when the feed speed becomes unstable, the distance between the molten wire tip and the base material to be welded changes slightly.

  In MIG welding of an Fe-based member, Cu plating or lubricating oil is applied to the surface of the Fe-based welding wire to reduce friction. However, in the case of welding of Ti, which is an active metal, applying Cu plating or lubricating oil to the surface of the wire reduces the strength of the welded joint due to the formation of brittle Cu-Ti intermetallic compounds and carbides. Can not be adopted. On the other hand, as a method for stabilizing the arc during welding, a method of introducing carbon dioxide gas or oxygen into the shield gas has long been adopted, but this method absorbs oxygen from the shield gas to the weld bead. In the case of Ti welding, it is not preferable because it leads to a decrease in the elongation of the welded joint.

  Also, when Ti spraying is performed, the same problems as in the case of welding basically occur. For example, in the case of arc spraying, since an arc is formed between two Ti wires, even if the supply speed of one wire is disturbed, the arc discharge gap interval changes and the arc becomes unstable. Therefore, it can be said that the problem of arc stability is more likely to occur than in the case of welding.

  The object of the present invention is to provide both excellent wire feedability and arc stability when performing welding or thermal spraying, etc., and also to ensure the mechanical properties of the obtained welded part and the quality of the sprayed layer. The object is to provide a Ti-based wire for forming a molten metal.

Means for Solving the Problems and Effects of the Invention

In order to solve the above problems, the molten metal-forming Ti-based wire of the present invention is a molten metal-forming Ti-based wire for forming a molten metal composed of a Ti-based metal by heating and melting sequentially from the tip side. The wire body is made of a Ti metal, the wire diameter is Dw, and the tensile strength in the wire longitudinal direction is
Smin = −230 Dw + 850 (unit: MPa)
Smax = −620Dw + 2000 (unit: MPa)
And a Ti-based oxide film is formed on the surface of the wire main body with a thickness of 1 μm or more and 5 μm or less.

  In the present specification, “Ti-based metal” refers to a Ti metal or a Ti alloy containing Ti as a main component (50 mass% or more). The Ti-based oxide film means an oxide film in which 50% by mass or more of the cation element is Ti. Moreover, the wire diameter Dw means a nominal value.

  The method for producing a molten metal forming Ti wire according to the present invention is a method for producing a molten metal forming Ti wire for forming a molten metal comprising a Ti metal by heating and melting sequentially from the tip side. By forming a Ti-based oxide film on the surface of a pre-processed wire composed of a Ti-based metal, and cold drawing the pre-processed wire together with the Ti-based oxide film, A Ti-based wire for forming a molten metal having a Ti-based oxide film formed on the surface with a thickness of 1 μm or more and 5 μm or less is obtained.

Since Ti is an active metal, a natural oxide film that forms a passive state on the surface in a room temperature atmosphere is formed. Since the natural oxide film suppresses corrosion inside the metal, Ti metal or Ti alloy containing Ti as a main component exhibits excellent corrosion resistance. However, the thickness of the natural oxide film is very thin, about 40 to 100 nm. What is formed on the surface of the wire in the present invention is a Ti-based oxide film that is thicker than the natural oxide film, specifically, having a thickness of 1 μm to 5 μm. Thus, by actively forming a Ti-based oxide film thicker than the natural oxide film on the surface of the wire, it is possible to greatly improve the feedability of the wire via a conduit tube, for example, arc welding or arc spraying. The stability of the arc when performing is also good. As a result, specifically, the following effects are achieved.
(1) By improving the feedability of the wire rod inside the conduit tube, the risk of clogging and buckling of the wire rod is greatly reduced and the frequency of process interruptions is reduced. Work efficiency is improved.
(2) By improving the stability of the arc, it is possible to improve the mechanical strength of the obtained welded portion and the quality of the sprayed layer. In particular, in the case of thermal spraying, since two Ti-based wires are fed simultaneously, the arc tends to be more disturbed due to the influence of the wire feeding property, but the Ti-based wire of the present invention should be adopted. Thus, arc spraying can be stably continued.

  Therefore, in the case of arc welding in which the arc is covered with an inert gas that does not contain oxygen, the effect (2) is particularly significantly achieved from the viewpoint of achieving arc stabilization. Moreover, in arc spraying, there are two types, a case where an oxygen-containing medium such as compressed air is used as an injection medium, and a case where an inert gas such as nitrogen or argon is used as a medium. The arc stabilizing effect is particularly remarkable when an inert gas is used as a medium.

  However, if the tensile strength of the wire is excessively small, the rigidity of the wire will be insufficient, and the wire will tend to buckle and deform during feeding, which may cause problems such as clogging of the wire inside the conduit tube. . On the other hand, if the tensile strength of the wire is excessively large, the flexibility of the wire is insufficient, and smooth feeding of the wire along a curved path by a conduit tube or the like may be hindered. Further, in a portion where the bend of the route forming member such as a conduit tube is particularly large, a problem that the inner surface of the route forming member is crushed easily due to interference with a highly rigid wire. Therefore, in the Ti-based wire for forming a molten metal according to the present invention, the tensile strength in the longitudinal direction of the wire composed of the Ti-based metal is considered in consideration of the buckling strength of the wire in order to suppress the above problems. Stipulated in the above range according to the wire diameter.

  In Ti-based wire rods, the strength of hot-worked and annealed materials decreases due to recovery and recrystallization, but the strength is reduced by cold wire drawing (generally refers to wire drawing at a temperature lower than the recovery and recrystallization temperature). It is possible to improve. Therefore, after forming a Ti-based oxide film thicker than the natural oxide film by oxidative heat treatment on the surface of the wire body, cold drawing at an appropriate processing rate (area reduction rate) can increase the tensile strength in the longitudinal direction of the wire. It becomes possible to control within the range of Smin to Smax. Further, Ti-based oxide films formed on the surface of a wire before processing by oxidation heat treatment are often relatively low in density and have low adhesion to the wire body due to the effect of volume expansion during oxidation. However, when cold-drawing is performed after that, the Ti-based oxide film is compressed in the wire diameter reduction direction in the wire drawing die to increase the density, and also has an adhesion force due to the effect of biting into the metal wire body. Enhanced.

  At this time, the Ti-based oxide film formed on the surface of the wire before processing is partly responsible for the lubrication function between the wire and the wire drawing die during the cold wire drawing. If the system oxide film is too thin, this lubrication effect is insufficient, and the dice mark is likely to be deeply etched on the surface of the wire, causing a defect. On the other hand, if the Ti-based oxide film is too thick, the ductility of the Ti-based oxide film is not so high by nature, and therefore, the Ti-based oxide film is easily peeled off when passing through a wire drawing die, and is uniform over the entire length of the wire. It becomes difficult to obtain a covered state of a Ti-based oxide film. Ti-based oxide film has low ductility and also has a large difference in thermal expansion coefficient with the underlying wire main body. Therefore, the decrease in adhesion when the film thickness increases is significant. In many cases, a considerable amount of cracks are formed in the film when it is formed on the surface of the film. In such a case, the Ti-based oxide film is more easily peeled off during the wire drawing process, and the adhesion between the remaining Ti-based oxide film and the wire body surface is low even after the wire drawing process. The Ti-based oxide film is likely to fall off when the wire is fed or fed in the conduit tube. Moreover, a considerable amount of cracks may be caused by cold drawing. When cracks are remarkably generated, lubricants and the like at the time of wire drawing tend to remain inside the cracks, and these impurities may be mixed into the molten metal. Therefore, in the Ti-based wire for forming a molten metal according to the present invention, the thickness of the Ti-based oxide film is specified to be 1 μm or more and 5 μm or less in order to suppress the above-described problems.

  In summary, if the tensile strength in the longitudinal direction is less than the above-described Smin, the wire rod is insufficiently rigid, and buckling deformation at the time of feeding, and consequently, wire rod clogging inside the conduit tube or the like tends to occur. In addition, when the tensile strength in the longitudinal direction of the wire exceeds the above-described Smax, smooth feeding of the wire along the curved path is hindered, and the inner surface of the route forming member such as a conduit tube is particularly disturbed at a portion having a large bend. Prone to be struck. Therefore, it is necessary to adjust the tensile strength of the wire to a range between Smin and Smax, but a Ti-based wire having such a strength can be manufactured by adjusting the processing rate (area reduction) of cold drawing. is there. When the thickness of the Ti-based oxide film is less than 1 μm, the lubrication effect at the time of wire drawing is insufficient, and a dice mark is deeply carved on the surface of the obtained wire, which causes the friction coefficient of the wire surface to deteriorate. . On the other hand, if the thickness of the Ti-based oxide film exceeds 5 μm, the Ti-based oxide film is likely to be peeled off when passing through a wire drawing die, and a uniform Ti-based oxide film covering state is obtained over the entire length of the wire. It becomes difficult. Further, the adhesion between the Ti-based oxide film and the surface of the wire main body is lowered, and the Ti-based oxide film is likely to drop off when the wire is used, or cracks are remarkably generated and the lubricant tends to remain at the time of wire drawing. Therefore, the thickness of the Ti-based oxide film is set to 1 μm or more and 5 μm or less, which makes it possible to form a smooth and uniform Ti-based oxide film on the surface of the wire body. In this case, the coverage ratio of the surface of the metal main body by the Ti-based oxide film (the portion thicker than the natural oxide film) is 70% or more, preferably 80% or more.

  In addition, it is desirable to keep the heat history added to a wire main body below 300 degreeC after cold wire drawing. If a thermal history exceeding 300 ° C. is applied, a new Ti-based oxide film with poor adhesion on the surface of the wire may be generated. Moreover, if a heat history is 300 degrees C or less, the tensile strength of a wire will hardly fall. More preferably, the heat history applied to the wire body is kept at 200 ° C. or lower.

  Further, after forming a Ti-based oxide film on the surface of the wire before processing, the Ti-based oxide film can be compressed together with the reduced diameter of the wire before processing by performing the cold wire drawing at a surface reduction rate of 10% or more. it can. Thereby, the biting force into the metal main body of the Ti-based oxide film is further increased, and the adhesion can be further improved. Then, after forming a Ti-based oxide film on the surface of the wire before processing, by applying the cold wire drawing at a surface reduction rate of 10% or more, the tensile strength in the longitudinal direction of the wire can be easily reduced from Smin to Smax. Can be controlled.

  Further, since the thickness of the Ti-based oxide film of the obtained wire is comparatively thin such as 1 μm or more and 5 μm or less, the formation time by the oxidation heat treatment can be shortened. Therefore, it is possible to adopt a method of forming a Ti-based oxide film by transporting the pre-processed wire in a strand state into an oxidation furnace and oxidizing the surface of the pre-processed wire. Since the oxidation heat treatment can be performed while continuously transporting the wire into the oxidation treatment furnace at a relatively high speed, the Ti-based oxide film can be efficiently formed, and the oxidation heat treatment can be performed in a strand state. Therefore, the Ti-based oxide film can be uniformly formed on the surface of the wire.

  At the time of wire drawing, it is necessary to consider lubrication between the inner surface of the wire drawing die and the surface of the wire. As is clear from the fact that the Ti-based oxide film has the effect of reducing internal friction with the conduit tube, the surface thereof is relatively smooth and also has the effect of reducing friction during wire drawing. Therefore, the Ti-based wire for forming a molten metal of the present invention manufactured by cold drawing in a state with a Ti-based oxide film thicker than a natural oxide film is compared with the conventional Ti-based wire for forming a molten metal, A wire rod having a more uniform wire diameter distribution and a good roundness can be obtained over the entire length of the wire rod.

  Specifically, the nominal value of the wire diameter Dw is set as the upper limit value, the value obtained by subtracting 0.02 mm from the nominal value is set as the lower limit value, and the wire diameter Dw falls between the upper limit value and the lower limit value over the entire length of the wire. In addition, it is possible to realize a wire whose roundness of the cross section of the wire is adjusted to 5 μm or less. By adjusting the wire diameter distribution and the roundness of the cross section as described above, not only the feeding performance of the wire is improved, but also the wire after drawing is aligned with a winding member such as a reel or bobbin. When winding, problems such as winding disturbance are less likely to occur, and the workability of the winding process can be improved. A Ti-based oxide film alone does not necessarily have sufficient lubricity at the time of wire drawing, and it is necessary to use a lubricant and a pretreatment film in combination. That is, since the lubricity is raised by the amount of Ti-based oxide film formed, even if a lubricant is applied under the same conditions, the lubrication performance is further improved by forming the Ti-based oxide film. In addition, from the viewpoint of obtaining equivalent lubricity, there is an advantage that the amount of lubricant applied can be reduced, and it also means that various problems described later due to remaining lubricant are reduced.

  By the way, when cold drawing is performed on a Ti-based wire having a Ti-based oxide film thicker than a natural oxide film, cracks are likely to occur in the Ti-based oxide film, and a lubricant is retained and remains in this crack. It becomes easy. In a weld bead or a sprayed layer formed using such a wire, a lubricant component may be mixed as an impurity, which may adversely affect strength and corrosion resistance. In addition, in the case of metal soap, for example, such a lubricant component contains oxygen, carbon, hydrogen and the like in the carboxylic acid molecular structure portion. Therefore, even if the amount of oxygen in the wire main body is regulated, if oxygen from the lubricant remains, it may be difficult to keep the oxygen content of the entire wire within the upper limit limit. Further, if impurities such as carbon and hydrogen, which are irrelevant to the formation of the Ti-based oxide film, remain in the form of a lubricant component, the carbon content and the hydrogen content of the entire wire are also specified as upper limit values (see Table 1, for example: (The standard upper limit value of hydrogen is set in the range of 0.008 mass% to 0.02 mass%, and the standard upper limit value of carbon is set in the range of 0.03 mass% to 0.1 mass%) It may be difficult to fit inside.

  Therefore, it is desirable to control the area ratio of cracks formed in the Ti-based oxide film (after wire drawing) to be 20% or less. The area ratio of the crack can be adjusted by the thickness of the Ti-based oxide film to be formed and the area reduction ratio of the wire drawing. It is desirable that the crack area ratio be as small as possible. However, if the thickness of the Ti-based oxide film is reduced too much, the effect of improving the wire feedability and arc stability will be insufficient, and the wire drawing process will be reduced. If the area ratio is too small, the production efficiency of the wire rod will be significantly reduced, so that the lower limit value is appropriately determined so that such problems do not occur.

  A Ti-based oxide film is formed on the surface of the wire before processing with a thickness of 1 μm or more and 5 μm or less, and a lubricant applying step for applying a lubricant to the surface of the Ti-based oxide film is performed, and a cold wire drawing step In the case of performing cold wire drawing while lubricating the inner surface of the wire drawing die and the surface of the wire before work with a lubricant by passing the wire rod before passing the wire to which the lubricant has been applied, In the finished wire after the wire drawing process, a lubricant removing step of removing the lubricant remaining on the Ti-based oxide film together with the lubricant held in the crack during the cold wire drawing process can be performed. . If the lubricant in the cracks is sufficiently removed, contamination as a weld bead or sprayed layer formed using the wire can be suppressed, which adversely affects the strength and corrosion resistance of the weld bead or sprayed layer. There is nothing. Furthermore, since the residual of the lubricant component such as metal soap is reduced, the residual oxygen from the lubricant is also reduced, and it becomes easier to keep the oxygen content of the entire wire within the upper limit of the standard. In addition, impurities contained in lubricants such as carbon and hydrogen, which are unrelated to the formation of Ti-based oxide films, can be reduced by reducing the residual amount of lubricant, and the carbon content and hydrogen content of the entire wire are also the upper limit of the standard. (Refer to Table 1: For example, hydrogen is 0.008% by mass or more and 0.02% by mass or less, and carbon is 0.03% by mass or more and 0.1% by mass or less).

  When a strong friction acts on the surface of the wire when removing the lubricant held in the crack, the formed Ti-based oxide film may be peeled off. Therefore, in order to suppress the separation as much as possible, it is desirable to clean the processed wire by immersing it in a cleaning solution. More specifically, it is effective to carry out the lubricant removing step as having a cleaning step of immersing the processed wire in the cleaning liquid and a water washing or hot water washing step of removing the cleaning liquid. In order to enhance the cleaning effect, it is possible to rub with a wiping medium softer than the wire, but sufficient care must be taken so as not to cause peeling of the oxide film. It is desirable that the final wire after cleaning or the like has a residual amount of lubricant of 1 g or less (including zero g) per 10 kg of the wire in order not to make the above-described failure of the lubricant remaining.

In the Ti-based wire for forming a molten metal according to the present invention, the ratio Tw / Dw between the thickness Tw of the Ti-based oxide film and the wire diameter Dw is adjusted in the range of 0.3 × 10 ⁻³ to 1 × 10 ^−1. It is desirable that When the ratio Tw / Dw between the thickness Tw of the Ti-based oxide film and the wire diameter Dw is less than 0.3 × 10 ⁻³ (0.03% of the wire diameter Dw), the effect of improving the feedability becomes insufficient. . In addition, the arc tends to become unstable, which is disadvantageous in forming a uniform weld bead or sprayed layer. On the other hand, when Tw / Dw is 1 × 10 ⁻¹ (10% of the wire diameter Dw) or more, the oxygen mixing ratio into the molten metal is increased, which may lead to adverse effects such as deterioration of the characteristics of the welded joint. In order to make the arc stabilization effect more prominent, the ratio Tw / Dw between the thickness Tw of the Ti-based oxide film and the wire diameter Dw is in the range of 1 × 10 ⁻³ to 50 × 10 ⁻³ . It is more desirable to adjust to. The thickness of the Ti-based oxide film can be specified as follows. That is, the cross section of the wire is mirror-polished and the oxygen concentration distribution is subjected to surface analysis by EPMA (Electron Probe Micro Analysis), and the peripheral region where the oxygen concentration is 7% by mass or more is specified as the Ti-based oxide film.

  The Ti wire for forming a molten metal of the present invention can be used as a Ti wire for welding that forms a weld metal as a molten metal. Moreover, it can also be used as a Ti wire for thermal spraying that forms a thermal spray metal layer as a molten metal.

  Moreover, the Ti-based wire for forming a molten metal of the present invention is mainly composed of Ti. When a Ti alloy is employed, various additive elements can be contained as subcomponents for the purpose of improving the strength or ductility of the obtained welded part or sprayed layer. Hereinafter, examples of additive elements that can be employed and ranges of desirable addition amounts are shown.

(1) Al: 9 mass% or less Al has the function of stabilizing the α phase, which is a low temperature phase of Ti, and strengthening it by dissolving in the α phase. However, if the content exceeds 9% by mass, a large amount of intermediate phase (intermetallic compound) such as Ti ₃ Al is formed, leading to inhibition of toughness or ductility. On the other hand, in order to make the above-mentioned effect remarkable, it is desirable to add 1% by mass or more, and more desirably in the range of 2 to 8% by mass.

(2) At least one of N and O: 0.5% by mass or less in total N and O also function as an α-phase stabilizing and reinforcing element similar to Al, and the effect of adding O is particularly remarkable. However, if the total content exceeds 0.5% by mass, toughness or ductility is hindered. On the other hand, in order to make the above effect remarkable, it is desirable to add 0.03% by mass or more in total, and more desirably, add in a range of 0.08 to 0.2% by mass in total. Is good. The oxygen content here means the oxygen content of the inner layer portion other than the Ti-based oxide film.

(3) One or more of V, Mo, Nb, and Ta: 45% by mass or less in total These elements are β-phase stabilizing elements that are Ti high-temperature phases, and have hot workability. This is effective in improving the strength and improving the heat treatment. However, all of these elements have a high specific gravity and a high melting point, and excessive addition leads to damage to the light weight and high specific strength characteristic of the Ti alloy. Since this will cause difficulty, the upper limit of the total addition amount is set to 45% by mass. On the other hand, in order to make the above effects remarkable, it is desirable to add 1% by mass or more in total. Mo and Ta may be added in a small amount to improve the corrosion resistance of the alloy.

(4) One or more of Cr, Fe, Ni, Mn and Cu: 15% by mass or less in total These elements also have the effect of stabilizing the β phase, improving hot workability and heat treatment It is effective in increasing strength through improvement. However, any of them easily forms an intermediate phase (for example, TiCr ₂ , TiFe, Ti ₂ Ni, TiMn, or Ti ₂ Cu) with Ti, and excessive addition leads to damage to ductility and toughness. The upper limit of the total addition amount is 15% by mass. On the other hand, in order to make the above effects remarkable, it is desirable to add 0.5% by mass or more in total. Ni may be added in a small amount to improve the corrosion resistance of the alloy.

(5) At least one of Sn and Zr: 20% by mass or less in total These elements are known as neutral additive elements that strengthen both the α phase and the β phase. However, excessive addition causes saturation of the effect, so the upper limit of the total addition amount is 20% by mass. On the other hand, in order to make the above effects remarkable, it is desirable to add 0.5% by mass or more in total.

(6) Si: 0.7% by mass or less Increases the creep resistance (creep rupture strength) of the alloy and has an effect of improving heat resistance. However, excessive addition causes a decrease in creep rupture strength or ductility due to the formation of an intermetallic compound such as Ti ₅ Si _3, so the upper limit of the addition amount is 0.7 mass%. On the other hand, in order to make the above-mentioned effect remarkable, it is desirable to add 0.03% by mass or more, and more desirably 0.05% to 0.5% by mass.

(7) At least one of Pd and Ru: 0.5% by mass or less in total The effect of improving the corrosion resistance of the alloy. However, since both are precious metals and expensive, the upper limit of the addition amount is set to 0.5% by mass in consideration of saturation of the effect. On the other hand, in order to make the above effect remarkable, it is desirable to add 0.02% by mass or more.

Specific examples of the alloy composition include the following (in addition, regarding the composition, Ti, which is the main component element, and the subcomponent elements are combined with a hyphen together with a composition value in which the unit of mass% is omitted. (For example, a Ti-6 mass% Al-4 mass% V alloy is described as Ti-6Al-4V).
(1) α-type alloy Ti-5Al-2.5Sn, Ti-5.5Al-3.5Sn-3Zr-1Nb-0.3Mo-0.3Si, Ti-2.5Cu
(2) Near α type alloy: Ti-6Al-2Sn-4Zr-2Mo-0.1Si, Ti-8Al-1Mo-1V, Ti-2.25Al-2Sn-4Zr-2Mo, Ti-6Al-2Sn-2Zr- 2Mo-0.25Si, Ti-6Al-2Nb-1Ta-0.8Mo, Ti-6Al-2Sn-1.5Zr-1Mo-0.35Bi-0.1Si, Ti-6Al-5Zr-0.5Mo-0. 2Si, Ti-5Al-6Sn-2Zr-1Mo-0.25Si
(3) α + β type alloy Ti-8Mn, Ti-3Al-2.5V, Ti-6Al-4V, Ti-6Al-6V-2Sn, Ti-7Al-4Mo, Ti-6Al-2Sn-4Zr-6Mo, Ti- 6Al-2Sn-2Zr-2Mo-2Cr-0.25Si, Ti-10V-2Fe-3Al, Ti-4Al-2Sn-4Mo-0.2Si, Ti-4Al-4Sn-4Mo-0.2Si, Ti-2. 25Al-11Sn-4Mo-0.2Si, Ti-5Al-2Zr-4Mo-4Cr, Ti-4.5Al-5Mo-1.5Cr, Ti-6Al-5Zr-4Mo-1Cu-0.2Si, Ti-5Al- 2Cr-1Fe
(4) β-type alloys Ti-13V-11Cr-3Al, Ti-8Mo-8V-2Fe-3Al, Ti-3Al-8V-6Cr-4Mo-4Zr, Ti-11.5Mo-6Zr-4.5Sn, Ti- 11V-11Zr-2Al-2Sn, Ti-15Mo-5Zr, Ti-15Mo-5Zr-3Al, Ti-15V-3Cr-3Al-3Sn, Ti-22V-4Al, Ti-15V-6Cr-4Al
(5) Near β type alloy: Ti-10V-2Fe-3Al,
(6) Corrosion resistant alloy (Can also be used for welding, but is particularly useful when you want to form a corrosion resistant coating layer by thermal spraying)
Ti-0.15Pd, Ti-0.3Mo-0.8Ni, Ti-5Ta

In the Ti-based wire for forming a molten metal of the present invention, the Ti-based oxide film can be formed by subjecting the Ti-based metal wire to a thermal oxidation treatment in an atmosphere containing oxygen. As the atmosphere containing oxygen, in addition to an oxygen-containing nitrogen atmosphere (including an air atmosphere) or an oxygen-containing inert gas atmosphere, a gas atmosphere containing an oxygen compound such as water vapor may be used. In order to efficiently form a Ti-based oxide film having a necessary and sufficient thickness, it is preferable to use an oxygen-containing atmosphere having an oxygen partial pressure of 5 to 21 × 10 ³ Pa, and the processing temperature is set to, for example, 500 to 800 ° C. It is good to do. In addition to the thermal oxidation treatment, a method of electrochemically oxidizing the surface layer can be employed. Specifically, an anodic oxidation method in a phosphoric acid solution is effective.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of an apparatus system for performing MIG welding using a Ti-based wire for forming a molten metal according to the present invention. Although this apparatus 300 is illustrated as performing MIG welding of an exhaust pipe EP for engine made of pure titanium or titanium alloy as a base material, for example, the present invention is not limited to this. In addition, a Ti-based wire for forming a molten metal (hereinafter also simply referred to as a wire) is composed of Ti or a Ti alloy (for example, Ti-6% Al-4% V). The wire rod 301 unwound from the reel 50 is guided to a flexible conduit tube 304 by a feeding roller 302 after the wire wrinkles are corrected by a correction roller 303. A torch 305 is provided at the distal end of the conduit tube 304, and an inert gas IG such as argon introduced from the rear end side of the conduit tube 304 passes from the distal end of the torch 305 to the welded portion of the exhaust pipe EP that is a member to be welded. It is sprayed and this is gas-shielded.

  In the torch 305, an electrode tip 306 that is electrically connected to the wire 301 is provided in a form that allows the wire 301 to be fed, and an arc AR is generated by applying a high pressure to the gap between the tip of the wire 301 and the exhaust pipe EP. The wire 301 is melted by the thermal energy of this arc and is dropped onto the welding site to form a weld bead WM. The feeding roller 302 feeds the wire 301 toward the arc AR continuously or intermittently in accordance with the speed at which the wire 301 is melted and consumed. The weld bead WM is at a high temperature immediately after solidification, and oxidation proceeds immediately when the shield is broken. Therefore, an after shield jig 307 that covers the top of the weld bead WM and a back shield that also covers the back of the weld bead WM are used. A jig 308 is provided.

FIG. 2 schematically shows a cross section of the wire 301. In the wire 301, the wire body 3 is made of Ti metal, and the tensile strength in the wire longitudinal direction is Smin = −230D + 850 (unit: MPa).
Smax = −620D + 2000 (unit: MPa)
The range is from Smin to Smax. A Ti-based oxide film 2 is formed on the surface of the wire main body 3 with a thickness of 1 μm or more and 5 μm or less. Further, the ratio Tw / Dw between the thickness Tw of the Ti-based oxide film 2 and the wire diameter Dw is 0.3 × 10 ⁻³ to 1 × 10 ⁻¹ , more preferably 1 × 10 ⁻³ to 50 × 10. ^-3 .

  By using the wire 301 having the Ti-based oxide film 2, the arc stability is improved. The reason is guessed as follows. That is, the wire 301 is preferentially heated from the surface layer portion by the skin current when an arc is generated, and the temperature is also high. As a result, the oxygen localized in the Ti-based oxide film 2 forming the surface layer portion evaporates at the initial stage of arc melting and flows out into the shielding gas atmosphere, and is the same as in the case of using a shielding gas containing oxygen. This is considered to stabilize the arc. Also, unlike the conventional case where a considerable amount of oxygen is introduced into the shielding gas itself, the amount of oxygen necessary and sufficient for arc stabilization is directly compensated by evaporation from the Ti-based oxide film, so that the shielding gas Compared with the addition of oxygen to the steel, it works effectively even in a small amount. As a result, the amount of oxygen taken into the weld bead can be reduced as compared with the conventional method, and the weld joint strength can be improved. In addition, there is a theory that the arc is oriented toward the oxide, and the stable arc and anode points are formed by regular oxide formation, so that the arc is stabilized.

  From the viewpoint of securing the joint properties of the welded portion obtained as the total amount of oxygen of the inner layer portion 3 and the Ti-based oxide film 2, the wire 301 is, for example, a type of industrial pure Ti plate defined in JIS: H4600 (2001). When welding two types of plates, it is desirable that the oxygen concentration be 0.15% or less.

  Further, the surface roughness of the surface of the wire rod on which the Ti-based oxide film 2 is formed is preferably 10 μm or less with the maximum height being Ry, from the viewpoint of improving the feedability in the conduit tube 304 of the wire rod 301. . The formation of the Ti-based oxide film 2 with the thickness and oxygen concentration as described above is naturally advantageous in obtaining a wire surface whose surface roughness is adjusted to such a numerical value. Moreover, in the said surface roughness, it is desirable that arithmetic mean roughness Ra is 0.5 micrometer or less. Further, the lower limit values of the maximum height Ry and the arithmetic average roughness Ra are not particularly limited, and are appropriately set in consideration of cost (the present inventors have at least Ra up to about 1.0 μm and Ra is at least about 1.0 μm. It has been confirmed that it can be reduced to about 0.1 μm). In addition, in this specification, surface roughness means what was measured by the method prescribed | regulated to JIS: B0601 (2001).

  The wire 301 can greatly reduce the dynamic friction coefficient on the surface of the wire by forming the Ti-based oxide film 2 as described above. Specifically, the surface dynamic friction coefficient of a conventional Ti wire rod whose surface is polished is about 0.5 to 0.6. However, by adopting the present invention, the dynamic friction coefficient is 0.4 or less, for example, 0. It can be reduced to about 2 to 0.3. The wire diameter Dw that is commonly used as the wire 301 is in the range of about 0.6 to 2.0 mm. When such a wire diameter Dw is employed, the Ti-based oxide film 2 is specifically formed. As a level of feed stability that can be achieved, for example, an average amplitude of a feed reaction force measurement profile obtained by measuring a reaction force in a wire feeding device can be 15 N or less. Since the feeding reaction force can be reduced in this manner, the occurrence of clogging of the wire 301 in the conduit tube 304 can be effectively suppressed.

  Further, in order to prevent the wire 301 from buckling in the conduit tube 304, the tensile strength in the longitudinal direction of the wire needs to be adjusted to the above-described Smax or more and Smin or less. That is, when the tensile strength in the longitudinal direction is less than Smin, the wire 301 is likely to be buckled and deformed at the time of feeding due to insufficient rigidity, and consequently the wire rod is clogged inside the conduit tube 304 (FIG. 1). On the other hand, when the tensile strength in the longitudinal direction of the wire 301 exceeds Smax, as shown in FIG. 1, smooth feeding of the wire in the flexible conduit tube 304 that can be bent freely is hindered, and particularly the bending is large. At the site, the inner surface of the conduit tube 304 is likely to be damaged. Therefore, it is necessary to adjust the tensile strength of the wire to Smin or more and Smax or less.

The wire 301 having the above strength can be manufactured by cold drawing. This will be specifically described below. First, a wire before rolling is obtained by rolling a wire rod using a Ti ingot (for example, one or two types of industrial pure titanium) as a raw material and then descaling. As shown in FIG. 3, the pre-processed wire 301 ′ is continuously conveyed in a strand state into the oxidation treatment furnace 46, the surface is oxidized, and a Ti-based oxide film is formed. For the oxidation treatment, for example, an oxygen-containing atmosphere having an oxygen partial pressure of 5 to 21 × 10 ³ Pa, for example, an oxygen-containing nitrogen atmosphere (including an air atmosphere) is used, and the treatment temperature is set to 500 ° C. to 800 ° C. (for example, 750 ° C.). Is set. The thickness of the Ti-based oxide film formed on the surface of the pre-processing wire 301 ′ is 1 μm or more and 5 μm or less, and in order to obtain the thickness, in the heating section of the oxidation processing furnace 46 set to the processing temperature, The conveyance speed of the pre-processing wire 301 ′ is adjusted according to the length of the heating section so that the passage time of the pre-processing wire 301 ′ is 1 to 10 minutes (for example, 6 minutes). This heat treatment improves the ductility of the pre-processed wire by recovery and recrystallization, and facilitates subsequent cold drawing and the like. In the present embodiment, the above-mentioned conveyance is performed while winding the pre-processing wire 301 ′ wound around the feed side roll 47 in a coil shape by the receiving side roll 48 by the motor 48m.

  As shown in FIG. 4, the pre-processing wire 301 ′ after forming the Ti-based oxide film passes through the lubricant 21 in the lubricant tank 20, and the lubricant is applied to the surface. The lubricant imparts a lubricating action between the wire drawing dies in the next wire drawing step and improves the wire drawing property. Note that the application of the lubricant 21 to the pre-processed wire 301 ′ can also be performed by charging a coiled wire into the lubricant tank 20 as shown in FIG. 5.

  As the lubricant, in addition to various metal soaps, graphite fluoride, molybdenum disulfide, and the like can be used, and two or more kinds can be used in combination. A trace amount of lubricant may remain on the surface of the wire even after the cleaning described later. In particular, in the case of a welding wire, it may lead to a decrease or variation in weld joint strength due to mixing of the lubricant component. Therefore, it can be said that it is more desirable to use a lubricant that is easy to decompose or evaporate when the wire is melted and is less likely to be mixed into the weld metal. Particularly desirable lubricants in this respect are those containing at least one of calcium stearate and calcium hydroxide. Moreover, what contains molybdenum disulfide can also be employ | adopted.

  The Ti-based oxide film formed on the surface of the pre-processed wire 301 'is smooth and has a small coefficient of friction, and the adhesion of the lubricant is not so good. Therefore, even if the pre-processed wire 301 ′ is buried in the lubricant powder as it is, a sufficient amount of lubricant may not be adhered. Therefore, as shown in FIG. 7, a pretreatment film 49 having a form in which scattered projections are uniformly dispersed is formed, and in this state, the preprocessed wire 301 ′ is elongated in the lubricant powder 21. It is effective to adopt a method of moving in the direction. In this way, the lubricant powder 21 is taken out by the convex portion of the pretreatment film 49 and adhered to the surface of the pre-processed wire 301 ′, thereby forming the lubricant powder layer 321. Due to the take-out effect of the lubricant powder 21 by the protrusions of the pretreatment film 49, the amount of adhesion of the lubricant powder greatly increases, and the lubricant powder 21 is formed by dispersing and forming the protrusions on the surface of the wire. Can be uniformly attached to the surface of the wire.

  The pretreatment film 49 can be easily and easily formed by, for example, applying a solution of a pretreatment film forming agent to the surface of the wire before processing and drying it. As the pretreatment film-forming agent, any one of water-soluble metal sulfate, water-soluble metal carbonate, fatty acid calcium and calcium hydroxide is used, and the aqueous solution of the pretreatment film-forming agent is applied to the surface of the wire before processing. A method of applying may be adopted. The pretreatment film-forming agent has an advantage that decomposition or evaporation is likely to proceed when the wire is melted, and is less likely to be mixed into the weld metal.

  In this embodiment, the Ti-based metal wire is thermally oxidized in an oxygen-containing atmosphere to form a Ti-based oxide film on the surface of the pre-processing wire 301 ′. The pretreatment film 49 can be formed by the following method. That is, as shown in FIG. 3, after the thermal oxidation treatment, a solution of the pretreatment film forming agent is applied to the surface of the pre-processed wire 301 ′ that has been heated, and the solvent of the solution is removed by the residual heat of the wire 301 ′. Evaporate to form a pretreatment film. According to this method, the wire 301 ′ is applied with a solution at a high temperature of, for example, 500 ° C. or more and 800 ° C. or less due to the thermal history of the Ti-based oxide film formation, so that the solvent (water) quickly evaporates due to the residual heat. As shown in FIG. 5, the pretreatment film 49 can be easily formed in a uniformly dispersed form without providing a drying device on the downstream side of the coating device 147. Further, since the evaporation of the solvent proceeds promptly, the pretreatment film 49 can be firmly adhered to the surface of the wire.

  In this case, as shown in FIG. 3, immediately after the thermal oxidation furnace 46 of the pre-processed wire 301 ′, the pretreatment film-forming agent solution coating device 147 (in this embodiment, the solution spray nozzle is used as the pre-process wire 301 And a Ti-based oxide film is formed through the thermal oxidation furnace 46 while conveying the pre-processed wire 301 'in the longitudinal direction (in the form of a strand), If the pre-processing wire rod 301 ′ after the formation of the Ti-based oxide film is subsequently conveyed to the coating device 147 and the solution of the pretreatment film forming agent is applied, the solution of the wire rod 301 ′ while the temperature of the wire rod 301 ′ is sufficiently high. Since application | coating can be performed, a pre-processing film | membrane can be formed more reliably. The coating device 147 may be substituted by a method in which the pre-processing wire 301 ′ is immersed in a solution of the film forming agent.

  The pre-processed wire 301 ′ with the pretreatment film formed is wound up by the receiving roll 48 and temporarily stored as shown in FIG. 3. Thereafter, the unprocessed wire 301 ′ with the pretreatment film formed thereon is supplied from the roll 48 to the lubricant tank 20 to form the lubricant powder layer 321 shown in FIG. 7. At this time, the pretreatment film-forming agent comprising the aforementioned water-soluble metal sulfate, water-soluble metal carbonate, fatty acid calcium, calcium hydroxide and the like has a relatively high hygroscopic property, so the pre-processed wire 301 ′ is pre-dried. After preliminary drying in the furnace 45 (FIG. 4), an improvement in lubrication performance can be expected by supplying the lubricant tank 20.

  As shown in FIG. 4, the pre-processing wire 301 ′ (FIG. 8) to which the lubricant is applied includes a die holder 31 and a wire drawing die 32 (for example, made of cemented carbide) fixed to the die holder 31. Are introduced into a cold wire drawing device 30. Specifically, by inserting the wire rod 301 ′ before processing into a wire drawing die 32 having a substantially conical section so that the outlet side has a smaller diameter than the inlet side, and pulling from the outlet side at room temperature, A wire 301 having substantially the same cross section as that of the outlet of the wire drawing die 32 is obtained. The wire 301 is wound around the wire spool 50 through the straightening portion 49 and used for the MIG welding described above. In addition, when it is not possible to reduce the surface to the desired wire diameter with a single wire drawing, a plurality of wire drawing may be repeated using a plurality of dies whose die diameters are sequentially reduced.

  The Ti-based oxide film formed on the surface of the pre-processed wire 301 ′ by the oxidation heat treatment is often low in density and low in adhesion to the wire body due to the effects of volume expansion during oxidation. However, by performing the cold wire drawing process as described above, the Ti-based oxide film 2 'is compressed in the wire rod diameter reducing direction in the wire drawing die to increase the density, and to the wire main body made of metal. As a result, the Ti-based oxide film 2 with improved adhesion due to the biting effect is obtained.

  Here, as shown in FIG. 8, in the pre-processed wire 301 ′, the Ti-based oxide film 2 ′ has low ductility and also has a large difference in thermal expansion coefficient with the underlying wire main body 3 ′. When the film thickness is increased, the adhesion force is remarkably reduced, and a considerable amount of crack CK is often generated in the film. Accordingly, if the thickness Tw ′ of the Ti-based oxide film 2 ′ exceeds 5 μm, the Ti-based oxide film 2 is likely to be peeled off when passing through the wire drawing die 30 and extends over the entire length of the wire. A uniform Ti-based oxide film coating state cannot be obtained. Further, since the adhesion between the Ti-based oxide film 2 'and the wire main body 3 is low, the Ti-based oxide film is likely to fall off even when the wire is used (for example, at the time of contact with a guide roll or the like).

  On the other hand, if the thickness Tw ′ of the Ti-based oxide film 2 ′ of the pre-processing wire 301 ′ is smaller than 1 μm, the lubrication effect during the Ti-based oxide film 2 ′ wire drawing process as shown in FIG. Insufficiently, the dice mark K is deeply etched on the surface of the obtained wire 301, which causes the friction coefficient of the wire surface to deteriorate. Therefore, the thickness of the Ti-based oxide film is set to 1 μm or more and 5 μm or less, whereby the smooth and uniform Ti-based oxide film 2 can be formed on the surface of the wire body 3.

  In FIG. 8, the Ti-based oxide film 2 ′ has a relatively smooth surface and has a friction reducing effect during wire drawing, as apparent from the fact that it has an internal friction reducing effect with the conduit tube. . Therefore, a wire rod having a more uniform wire diameter distribution and a good roundness can be obtained over the entire length of the wire rod as compared with a conventional Ti metal wire for forming a molten metal. Specifically, the nominal value of the wire diameter Dw is set as the upper limit value, the value obtained by subtracting 0.02 mm from the nominal value is set as the lower limit value, and the wire diameter Dw falls between the upper limit value and the lower limit value over the entire length of the wire. In addition, it is possible to realize a wire whose roundness of the cross section of the wire is adjusted to 5 μm or less. This not only improves the feedability of the wire 301 during use of FIG. 1, but also when winding the wire 301 after drawing in alignment with the reel 50 in FIG. Problems are less likely to occur, and the workability of the winding process can be improved. In this case, the maximum value of the wire diameter Dw in the entire length of the wire rod 310 represents a nominal value.

  In FIG. 8, the hole diameter of the die hole 31h of the wire drawing die 32 is adjusted so that the area reduction rate of the cold wire drawing is in the range of 20% to 70% according to the wire diameter of the pre-processing wire 301 ′. ing. The area reduction ratio is set so that the area ratio of the crack CK after drawing is 20% or less in consideration of the thickness of the Ti-based oxide film 2. When the crack CK is formed in the Ti-based oxide film 2 ′ when the cross section of the drawn wire is reduced, the lubricant 321 ′ applied to the surface of the pre-processing wire 301 ′ is pushed into the crack CK. Since the lubricant remaining in the crack is likely to remain on the surface of the wire, as described later, it is necessary to sufficiently remove the lubricant by dipping in the cleaning liquid in consideration of suppression of peeling of the Ti-based oxide film 2.

  The Ti-based oxide film formed on the surface of the pre-processed wire 301 ′ by the oxidation heat treatment is often low in density and low in adhesion to the wire body due to the effects of volume expansion during oxidation. However, by performing the cold wire drawing process as described above, the Ti-based oxide film 2 'is compressed in the wire rod diameter reducing direction in the wire drawing die to increase the density, and to the wire main body made of metal. As a result, the Ti-based oxide film 2 with improved adhesion due to the biting effect is obtained.

  As shown in FIG. 13, in the pre-processed wire 301 ′, the Ti-based oxide film 2 ′ has a low ductility and also has a large difference in thermal expansion coefficient with the underlying wire main body 3 ′. When the thickness Tw ′ of the oxide film 2 ′ increases excessively, specifically when it exceeds 5 μm, a considerable amount of cracks are often generated in the film. Since this crack holds a large amount of lubricant, it has an adverse effect of increasing the amount of impurities mixed into the weld bead or the sprayed layer.

  Returning to FIG. 8, in the processed wire 301 after the cold drawing as described above, the lubricant tends to remain in the crack. In addition, some lubricant may remain on the Ti-based oxide film 2. Therefore, as shown in FIG. 9, the processed wire 301 is guided to the cleaning tank 56, and the processed wire 301 is immersed in the cleaning liquid 57 for cleaning (cleaning step). As the cleaning liquid, for example, an alkaline cleaning liquid (for example, mainly composed of a surfactant) that is soluble in the above-described metal soap, which is the main component of the lubricant, can be used. By this cleaning, the water-soluble pretreatment film and the lubricant adhering to the region other than the crack CK can be removed. If water-soluble metal sulfate, water-soluble metal carbonate, fatty acid calcium and calcium hydroxide are used as the pretreatment film forming agent, the pretreatment film forming agent can be easily dissolved and removed by the above washing and auxiliary washing. It is possible to reduce the residual amount on the surface of the wire after the treatment. As a result, the residual oxygen from the pretreatment film-forming agent is also reduced, and it becomes easier to keep the oxygen content of the entire wire within the standard upper limit value. In addition, impurities such as carbon and hydrogen, which are unrelated to the formation of the Ti-based oxide film, are reduced by reducing the residual pre-treatment film forming agent, and the carbon content and hydrogen content of the entire wire are within the upper limit of the standard. Can be easily accommodated. In addition, after washing | cleaning, the wire 301 after washing | cleaning is dried with the drying apparatus 65 by the air spray etc. which were provided in the downstream.

  On the other hand, with respect to the lubricant, those adhering to the region other than the crack CK can be removed relatively easily by the above cleaning, but the lubricant retained inside the crack CK should be sufficiently removed only by cleaning. Can be difficult. Therefore, after the cleaning process, the surface of the processed wire 301 wet with the cleaning liquid is rubbed with a wiping medium 62 softer than the wire to wipe off the lubricant press-fitted into the crack CK. Is effective. By this wiping, the lubricant is sufficiently removed from the crack CK, and the amount of lubricant remaining on the surface of the wire 301 is greatly reduced. As a result, the residual oxygen from the lubricant is reduced, and it becomes easier to keep the oxygen content of the entire wire within the standard upper limit. In addition, impurities such as carbon and hydrogen, which are unrelated to the formation of the Ti-based oxide film, are reduced by reducing the residual lubricant, and the carbon content and hydrogen content of the entire wire can be easily within the specified upper limit. Can fit. In this case, the material and pressing pressure of the wiping medium 62 should be appropriately selected, and the Ti-based oxide film should not be peeled off.

  In the present embodiment, an auxiliary cleaning tank 150 by spraying warm water is provided on the downstream side of the cleaning tank 56, and further, the wire rod 301 continues to be conveyed with respect to the wire 301 conveyed through the cleaning tank 56 and the auxiliary cleaning tank 150. A wiping device 60 is provided in which a strip-like wiping medium 62 is brought into contact with the wiping medium 60 to perform a wiping process on the surface of the wire.

  Returning to FIG. 8, by reducing the residual lubricant in the crack CK as described above, it is possible to suppress contamination as an impurity into the weld bead formed using the wire, and the strength and characteristics of the weld bead. Will not be adversely affected. The residual amount of lubricant should be 1 g or less, preferably 0.5 g or less per 10 kg of wire (including zero g). Further, the formation area ratio of cracks is preferably adjusted to 20% or less.

  In addition, said wire 301 can also be used as a wire for thermal spraying. FIG. 16 schematically shows an example of the thermal spraying apparatus. The thermal spraying device 400 includes a thermal spray gun 302 and a thermal spray unit 303. In the thermal spraying unit 303, the two wire rods 301 and 301 wound around the reels 312 and 312 are respectively fed to the thermal spray gun 302 through the conduit tube 310. In this embodiment, the wire rods 301 and 301 are fed in such a manner that the wire rods 301 and 301 are drawn from the thermal spray unit 303 by feed rollers 308 and 308 provided on the thermal spray gun 302. The wire rods 301 and 301 may be fed toward the thermal spray gun 302 by a feed roll provided in the above, or both may be used in combination.

  In the thermal spray gun 302, the wire rods 301 and 301 pass through the respective energizing holders 304 and 304 in an electrically conductive state, and then are sent out in a direction in which the tip portions approach each other. When the wire rods 301 and 301 are energized by the DC arc power source 314 on the thermal spraying unit 303 side via the energization holders 304 and 304, arc discharge is generated in the gap G formed between the tips of the wire rods 301 and 301, and the wire rod 301 , 301 is melted to generate molten metal. An injection nozzle 310 is disposed at a position facing the gap G, and an injection medium made of air or an inert gas such as nitrogen or argon is supplied to the injection nozzle 310 through the injection medium passage 309 by the compressor 313 on the thermal spraying unit 303 side. Is done. Then, the molten metal formed in the gap G is sprayed on the surface of the workpiece 307 together with the jetting medium, and the sprayed layer 306 is deposited. Since the wires 301 and 301 are continuously fed to the gap G while being sequentially melted from the tip side by arc discharge, spraying can be continued by continuing to supply the medium to the spray nozzle.

  Thus, in the case of thermal spraying, two wire rods 301 and 301 are fed in parallel, and an arc is formed in the gap G between the tips, so that the supply speed of one wire rod 301 advances or lags with respect to the other. Then, the gap G varies and arc instability is likely to occur. However, by adopting the present invention, the feeding speed of the wires 301 and 301 with respect to the gap G can be stably maintained, so that the stability of the arc can be greatly improved, and as a result, a high quality sprayed layer 306 is formed. it can.

  In the embodiment described above, the entire wire 301 is made of Ti metal as shown in FIG. 2, but only the surface layer portion of the wire 301 is made of Ti metal as shown by a one-dot chain line in FIG. It is also possible to form a composite wire having another metal layer 4 formed therein. For example, when a welded part or sprayed layer is to be made of a Ti alloy, a metal layer 4 (for example, Al, V, Al-V alloy, etc.) made of the alloy component is provided to form a molten metal. It can be alloyed with the Ti metal forming the outer layer. By ensuring that the outer layer is a Ti metal layer on which the Ti-based oxide film 2 is formed, it is possible to ensure better feeding stability and arc stability of the wire than when the entire wire is made of a single alloy layer. Can do. If a wire filled with ceramic powder is used instead of the metal layer 4, a metal-ceramic composite material (for example, cermet) can be sprayed. Furthermore, the thermal spraying method is not limited to arc spraying, and flame spraying, laser spraying, gas spraying, plasma spraying, etc. can be adopted as long as a linear spraying material can be used. Also in these thermal spraying methods, the effect of stabilizing the feeding of the wire is similarly achieved, contributing to the formation of a uniform thermal spray layer.

Hereinafter, experimental results performed to confirm the effects of the present invention will be described.
(Example 1)
First, a titanium wire material (corresponding to one type of industrial pure titanium: wire diameter 1.6 mm) defined in JIS: H4670 (1993) as a material is maintained in a nitrogen atmosphere (oxygen partial pressure 21 × 10 ³ Pa). The pre-processing wire having various Ti oxide films was obtained by performing an oxidation heat treatment at 500 to 800 ° C. for 1 to 60 minutes using the oxidation treatment furnace. This material is cold-drawn (number of machining passes: 6 times, the area reduction rate per stroke is about 14.5%), and the wire diameter is 1.0 mm (nominal value depending on the die hole diameter in the final stage) Thus, Ti metal wires for forming a molten metal having Ti oxide films having various thicknesses shown in Table 1 were obtained (Nos. 1 to 6). In addition, for comparison, a wire (No. 6) subjected to a wire annealing (No. 6) after a titanium wire material is vacuum-annealed at 600 ° C. for 1 hour and then subjected to an oxidation heat treatment for forming a Ti oxide film having the same thickness as No. 3 is drawn. Created. The processed wire was wound on a reel having a diameter of 280 mm and a width of 100 mm. The following measurements and evaluations were performed on these wires.

(1) Thickness Tw of Ti-based oxide film
The cross section of the wire (10 randomly extracted points) is mirror-polished, and the oxygen concentration distribution is analyzed by EPMA (Electron Probe Micro Analysis), and the peripheral region where the oxygen concentration is 7% or more is specified as a Ti-based oxide film The average thickness in the circumferential direction and the line length direction was calculated.

(2) Tensile strength A test piece having a length of 100 mm was cut out from the wire, tensioned at a crosshead speed of 1.0 mm / min using an Instron type tensile tester, and a stress-strain curve was measured. The maximum stress value was read as the tensile strength.

(3) Surface roughness In the form of setting the evaluation length in the longitudinal direction of the wire, the roughness curve is measured by the method defined in JIS: B0601 (2001), and the maximum height Ry (μm) and the arithmetic average roughness Each value of Ra (μm) was read.

(4) Feeding stability evaluation The wire was set in the MIG welding apparatus 300 of FIG. 1, and welding was performed at a wire feed speed of 75 mm / second and a current of 90 A. The length of the conduit tube 304 is 3 m. If the wire can be welded without any trouble, ○ (good feedability), and × (when feedability is unstable) when buckling occurs in the wire at the start of welding. Judged.

(5) Coefficient of dynamic friction It was measured using a Bowden-Leven type friction tester. Specifically, the wire sample is mounted on the sample table, the steel material for pressing is stacked from above, and the friction force when the sample table is moved at a constant speed while pressing the steel material with a weight of a constant weight, It is detected by a strain gauge type load detector.
(6) Covering state of Ti oxide film after wire drawing The distribution of oxygen content is investigated over the entire length of the wire after wire drawing, and the variation rate of oxygen content in the wire length direction is within 5%. (◯) A value exceeding 5% and 10% or less was acceptable (Δ), and a value exceeding 10% was evaluated as defective (x). A wire rod with a large dropout of the Ti oxide film at the time of wire drawing has a large variation rate of the oxygen content because the oxygen content at the dropout portion is greatly reduced.
(7) Presence or absence of wire-drawing flaws The wire after wire drawing was visually observed using a magnifying glass with a magnification of 10 times. ).
(8) Presence or absence of Ti oxide film falling off during wire feeding In (4), the deposit after the feeding of the wire rod was almost free from depositing Ti oxide film was good (O), notable Those that were found in the above were judged as bad (x).
(9) Sectional roundness of wire after wire drawing Measured at 10 arbitrary points from the wire full length by the method defined in JIS: B7451 (1997), and the average value was calculated. Further, the wire diameter distribution was measured over the entire length, and the maximum value and the minimum value were obtained.
(10) Reel winding property evaluation 5 kg of a wire was wound on a reel, and it was confirmed whether or not aligned winding was possible.

The results are shown in Table 1.

  According to this result, it can be seen that the feeding stability of the wire is good when the tensile strength of the wire is 620 MPa (the value of Smin described above when D is about 1 mm) or more. When the thickness of the Ti oxide film is 1 μm or more and 5 μm or less, the coated state with the Ti oxide film after wire drawing is good, and there is no generation of dice marks after wire drawing, and a wire with good performance is obtained. You can see that The wire diameter distribution also has a nominal value Dw as an upper limit value and Dw−0.02 (mm) as a lower limit value, and the wire diameter distribution is within this range, and the roundness is 5 μm or less. Thereby, not only the feeding stability is improved, but also the reel winding property is good.

The schematic diagram which shows the outline of the MIG welding apparatus of Ti used as the application object of this invention. The cross-sectional schematic diagram of the Ti-type wire for molten metal formation of this invention. Explanatory drawing of the manufacturing process of the Ti-type wire for molten metal formation of this invention. Explanatory drawing following FIG. Explanatory drawing which shows another process of FIG. The figure explaining the formation concept of a pre-processing film. The effect explanatory view of a pretreatment coat. The figure explaining the effect which wire drawing has on the property of Ti system oxide film. The conceptual explanatory drawing of the cleaning and wiping process after wire drawing. The figure explaining a mode that the cross-sectional roundness of the wire before a process affects lubricant distribution. Explanatory drawing of the preliminary process for raising cross-sectional roundness. The SEM observation image and EDX analysis profile which show an example of the surface normality of Ti system oxide film after wire drawing with the influence which it has on the lubricant residual state of the process of washing and wiping off. The figure explaining the problem at the time of forming a Ti-type oxide film too thickly. The figure explaining the problem at the time of forming a Ti-type oxide film too thinly. The schematic diagram which shows the principal part of a MIG welding apparatus. The schematic diagram which shows the outline of the arc spraying apparatus of Ti used as the application object of this invention.

Explanation of symbols

2 Ti-based oxide film 3 Inner layer 21 Lubricant CK crack 46 Thermal oxidation treatment furnace 147 Coating device 49 Pretreatment film 62 Belt (wiping medium)
301 Ti-based wire for forming molten metal 321 Lubricant powder layer

Claims (16)

A molten metal-forming Ti-based wire for forming a molten metal composed of a Ti-based metal by heating and melting sequentially from the tip side, wherein the wire body is composed of a Ti-based metal, and the wire diameter is Dw. The tensile strength in the longitudinal direction is
Smin = −230 Dw + 850 (unit: MPa)
Smax = −620Dw + 2000 (unit: MPa)
A Ti-based wire for forming a molten metal, characterized in that a Ti-based oxide film having a thickness of 1 μm or more and 5 μm or less is formed on the surface of the wire body. The ratio Tw / Dw of the thickness Tw of said Ti-type oxide film and the wire diameter Dw is adjusted to the range of 0.3 * 10 < ^-3 > ^-1 * 10 < ^-1 >, For molten metal formation of Claim 1 Ti wire.   The molten metal-forming Ti-based wire according to claim 1 or 2, wherein the surface roughness of the surface of the wire has a maximum height Ry of 10 µm or less.   The Ti-based wire for forming a molten metal according to any one of claims 1 to 3, wherein a dynamic friction coefficient of the surface of the wire is 0.4 or less.   The Ti system for forming a molten metal according to any one of claims 1 to 4, wherein the wire diameter Dw is 0.6 mm or more and 2.0 mm or less, and an average amplitude of a feeding reaction force is 15 N or less. wire.   The nominal value of the wire diameter Dw is the upper limit value, the value obtained by subtracting 0.02 mm from the nominal value is the lower limit value, and the wire diameter Dw is within the upper limit value and the lower limit value over the entire length of the wire. The Ti-based wire for forming a molten metal according to any one of claims 1 to 5, wherein the roundness of the cross section of the wire is adjusted to 5 µm or less.   The Ti-based wire for forming a molten metal according to any one of claims 1 to 6, wherein an area ratio of cracks formed in the Ti-based oxide film is 20% or less.   The Ti-based wire for forming a molten metal according to claim 7, wherein a residual amount of the lubricant is 1 g or less per 10 kg of the wire.   A method of manufacturing a molten metal-forming Ti-based wire for forming a molten metal composed of a Ti-based metal by sequentially heating and melting from the tip side, and a Ti-based material on the surface of a pre-processed wire composed of the Ti-based metal By forming an oxide film and cold drawing the pre-processed wire together with the Ti-based oxide film, the Ti-based oxide film has a thickness of 1 μm or more and 5 μm or less on the surface of the wire body made of Ti-based metal. A method for producing a Ti-based wire for forming a molten metal, comprising: forming a Ti-based wire for forming a molten metal.   The manufacturing method of the Ti type | system | group wire for molten metal formation of Claim 9 whose heat history added to the said wire main body after the said cold wire drawing is 300 degrees C or less.   Claims: The Ti-based oxide film is compressed together with the reduced diameter of the pre-processed wire rod by forming the Ti-based oxide film on the surface of the unprocessed wire rod and then cold-drawing at a surface reduction rate of 10% or more. The manufacturing method of the Ti-type wire for molten metal formation of claim | item 9 or claim | item 10.   12. The Ti-based oxide film is formed according to claim 9, wherein the Ti-based oxide film is formed by conveying the pre-processed wire in a strand state into an oxidation furnace and oxidizing the surface of the pre-processed wire. The manufacturing method of the Ti-type wire for molten metal formation of description. After forming the Ti-based oxide film on the surface of the pre-processed wire, the cold drawing is performed at a surface reduction rate of 10% or more, thereby obtaining the tensile strength in the longitudinal direction of the wire as the wire diameter Dw. ,
Smin = −230 Dw + 850 (unit: MPa)
Smax = −620Dw + 2000 (unit: MPa)
The manufacturing method of the Ti type | system | group metal wire for molten metal formation of any one of Claim 9 thru | or 12 controlled to the range of Smin or more and Smax or less represented by these.   Forming a Ti-based oxide film with a thickness of 1 μm to 5 μm on the surface of the pre-processed wire, and applying a lubricant to the Ti-based oxide film surface; In the process, the cold-drawn wire is processed while lubricating the inner surface of the wire drawing die and the surface of the wire before working with the lubricant by passing the wire before drawing with a lubricant through a wire drawing die. In the processed wire after the cold wire drawing, the lubricant remaining on the Ti-based oxide film is removed together with the lubricant retained in the crack during the cold wire drawing. The manufacturing method of the Ti type | system | group wire for molten metal formation of any one of Claim 9 thru | or 13 which has a process.   The method for producing a molten metal-forming Ti-based wire according to claim 14, wherein the lubricant contains any one of calcium stearate, calcium hydroxide, and molybdenum disulfide.   The nominal value of the wire diameter Dw is the upper limit value, the value obtained by subtracting 0.02 mm from the nominal value is the lower limit value, the wire diameter Dw is adjusted between the upper limit value and the lower limit value over the entire length of the wire, And the manufacturing method of the Ti type | system | group wire for molten metal formation of any one of Claim 9 thru | or 15 which adjusts the roundness of a wire cross section to 5 micrometers or less.