Joining method of titanium or titanium-based alloy material

Abstract

To provide a joining method of titanium or titanium-based alloy material capable of easily producing suitable joint of titanium or titanium-based alloy material in a short time at low cost.SOLUTION: In a method for joining titanium or titanium-based alloy material 1 to metal base material 2, the whole of the titanium or titanium-based alloy material 1 is resistance-welded to the metal base material 2 in a state that the whole of the titanium or titanium-based alloy material is covered with nickel powder 3.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a method for joining titanium or titanium alloy material to a metal base material. [Background technology]

[0002] In general, titanium has a strong oxide film layer on its surface, a high melting point (1400°C), and the property of oxidizing at low temperatures (around 400-500°C), making it hard and brittle, making it difficult to weld (join).

[0003] Conventionally, methods for joining titanium or titanium alloy materials (hereinafter also referred to as titanium materials) have been known (for example, Patent Document 1). In Patent Document 1, a diffusion bonding method is used in which a well-known antioxidant is applied to the joining surfaces of, for example, two halves of a thick-walled titanium structure, and then the atoms of the joining surfaces are diffused to join them. For example, aluminum powder is used as the antioxidant. In this case, the joining is performed in an argon gas atmosphere by TIG welding, or in a vacuum by vacuum beam welding, while oxygen is blocked.

[0004] The above joining methods are performed on a relatively large joining surface, and are not considered suitable for joining titanium materials such as wire rods. On the other hand, joining titanium materials using solder (brazing) is also conceivable, but as mentioned above, the surface of titanium materials has a strong oxide film layer that does not adhere well to solder, making joining with solder inherently difficult. Furthermore, if done in air, the titanium material is prone to oxidation due to its properties, making it brittle, so it must be done in an inert gas or vacuum to block oxygen. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 1486 / 1986 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, joining of titanium material and metal base material must be carried out in an inert gas or vacuum, which requires large-scale equipment and is time-consuming and costly to produce (mass-produce).

[0007] In particular, it has been almost impossible to achieve ultra-fine titanium wires used in shape memory alloys, etc. Thus, there has been a demand for a technology that can properly join titanium materials in a short time and at low cost.

[0008] An object of the present invention is to solve the above problems and to provide a method for joining titanium or titanium-based alloy materials, which can easily produce suitable joined titanium or titanium-based alloy materials in a short time and at low cost. [Means for solving the problem]

[0009] In order to achieve the above object, the method for joining titanium materials according to the present invention is a method for joining titanium materials to a metal base material, in which the titanium material is entirely covered with nickel powder and then resistance-welded to the metal base material.

[0010] According to this configuration, resistance welding is performed in the atmosphere using a large current and pressure in a short time, making the titanium material less susceptible to heat and less likely to become embrittled. In addition, since the titanium material is joined to the metal base material while being entirely covered with nickel powder, the numerous nickel powder particles block oxygen around the titanium material to some extent during welding, and the heat applied to the titanium material is diffused through this nickel powder, suppressing temperature rise in the titanium material and preventing embrittlement. This makes it possible to easily produce appropriate titanium material joining in a short time and at low cost.

[0011] In the present invention, the titanium material may be a wire material, which makes it possible to join titanium materials such as ultrafine wires, which has been difficult to achieve in the past.

[0012] The present invention may also include a first step of placing nickel powder on the metal base material and resistance welding the metal base material to form a nickel undercoat that covers the underside of the titanium material, a second step of placing the titanium material on the nickel undercoat and then placing nickel powder on top of that to form a nickel overcoat that covers the upper side of the titanium material, and a third step of resistance welding the titanium material together in a state where the upper and lower sides of the titanium material are entirely covered with the nickel powder through steps one and two. In this case, appropriate joining of titanium materials can be produced more easily in a short time and at low cost.

[0013] Preferably, in the third step, the nickel powder covering the titanium or titanium-based alloy material is also resistance-welded to each other, so that the joining of the titanium material is strengthened not only by the joining of the titanium material and the nickel powder but also by the joining of the nickel powder itself.

[0014] Preferably, multiple wires of the titanium or titanium alloy material are bonded together to a metal base material. In this case, the bonding strength between the titanium or titanium alloy material wire and the metal base material is increased. After bonding, the wires can be cut lengthwise into individual pieces, allowing for efficient production of single-wire bonding. [Effects of the Invention]

[0015] In this invention, resistance welding is performed in the atmosphere using a large current and pressure in a short time, so the titanium material is less susceptible to heat and less likely to become embrittled. In addition, the titanium material is joined to the base metal while being entirely covered with nickel powder, so that during welding, the numerous nickel powder particles block oxygen around the titanium material to some extent, and the titanium material is thermally diffused through this nickel powder, suppressing temperature rise in the titanium material and preventing embrittlement. This makes it possible to easily produce appropriate titanium material joining in a short time and at low cost. [Brief explanation of the drawings]

[0016] [Figure 1]1 is a front view showing a resistance welding apparatus for performing a method for joining a titanium or titanium-based alloy material to a metal base material according to an embodiment of the present invention. [Figure 2] 1 is a schematic perspective view showing the operation of a method for joining titanium or titanium-based alloy materials according to one embodiment of the present invention. FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] 10A to 10C are estimated cross-sectional views showing the operation of the joining method. [Figure 10] 10A and 10B are schematic perspective views showing the operation of a modified example of a method for joining titanium or titanium-based alloy materials. DETAILED DESCRIPTION OF THE INVENTION

[0017] Preferred embodiments of the present invention will now be described with reference to the drawings. Fig. 1 is a front view showing a resistance welding apparatus 20 for performing a joining method for joining a titanium or titanium-based alloy material (hereinafter also referred to as a titanium material) to a metal base material according to one embodiment of the present invention.

[0018] As shown in Figure 1, resistance welding apparatus 20 operates in the atmosphere with a pair of welding electrodes 10, 11 supplied with power from a welding power source 15, and with a titanium material 1 placed on a metal base material 2, such as Cu (copper) or a copper alloy, under pressure, electricity is passed between welding electrodes 10, 11, causing a welding current A to flow. As a result of the high current (low voltage) welding current A flowing between titanium material 1 and metal base material 2 while pressure is being applied, a nugget (alloy layer) N is formed between titanium material 1 and metal base material 2 due to resistance heating of the metal, and titanium material 1 is resistance welded to metal base material 2.

[0019] In this example, the titanium material is a wire-like titanium material (hereinafter also referred to as titanium wire) 1. Resistance welding is performed in a short time by passing a large current while applying pressure, so compared to other welding methods, the titanium wire 1 is less susceptible to the effects of heat and is less likely to become embrittled. The titanium wire 1 is an extremely thin wire of a titanium alloy material, for example, several tens of micrometers thick, which is used in shape memory alloys. In this case, it is possible to join extremely thin titanium wires, which was previously difficult to achieve.

[0020] 2 to 8 show the operation of the joining method for joining the titanium wire 1 to the metal base material 2 through the first step S1 to the third step S3.

[0021] First, in a first step S1, as shown in FIG. 2, a large number of Ni (nickel) powders 3 are placed on a metal base material 2. In this state, as shown in FIG. 3, the metal base material 2 is placed between electrodes 10 and 11, and current is passed through them to perform resistance welding. In this way, as shown in FIG. 4, the Ni powder 3 is solidified and bonded onto the metal base material 2, and a nickel base 4 is created that temporarily bonds the Ni powder 3. The nickel base 4 bonded to the metal base material 2 covers the underside of the Ti (titanium) wire 1. For example, a powder of 20 μm or less is used as the Ni (nickel) powder 3.

[0022] Next, in the second step S2, as shown in Fig. 5, the Ti wire 1 is placed on the nickel underlayer 4. Next, as shown in Fig. 6, a large number of Ni powder particles 3 are placed on the Ti wire 1. The placed Ni powder particles 3 cover the upper side of the Ti wire 1.

[0023] In the third step S3, as shown in Fig. 7, the metal base material 2, nickel substrate 4, Ti wire 1, and Ni powder 3 are placed between electrodes 10 and 11, and current is passed through them to perform resistance welding. As a result, the Ti wire 1 is resistance-welded with the entire upper and lower sides covered with Ni powder 3. In this way, as shown in Fig. 8, the Ni powder 3 around the Ti wire 1 is nickel-fixed 5 by resistance welding, and the metal base material 2, Ti wire 1, and Ni powder 3 are integrated.

[0024] At this time, the Ti wire 1 and the Ni powder 3 are joined at multiple contact points 6 (Fig. 9). The Ni powders 3, 3 covering the Ti wire 1 are also resistance-welded to each other and joined at multiple contact points 7 (Fig. 9). In this case, the joining is stronger not only between the Ti wire 1 and the Ni powder 3 but also between the Ni powders 3 themselves.

[0025] 9, in the third step S3, multiple contact points 6 between the Ti wire 1 and the Ni powder 3 are formed around the Ti wire 1, and the fine contact points of the Ni powder 3 access the Ti wire 1, allowing electrical conduction and resistance welding, and during this welding, the numerous Ni powders 3 seal the periphery of the Ti wire 1, blocking oxygen to some extent, and it is thought that the heat applied to the Ti wire 1 is diffused via the Ni powder 3. In this way, the temperature rise of the Ti wire can be suppressed.

[0026] Furthermore, around the periphery, the Ni powder 3 on the nickel base 4 and the Ni powder 3 covering it from above are bonded to each other, forming a plurality of contact portions 7 between the Ni powders 3, 3. It is estimated that small nuggets (alloy layers) N ​​are formed at each of these plurality of contact portions 6, 7. In this way, it is thought that the bonding between the Ti wire 1 and the Ni powder 3 as well as the bonding between the Ni powders 3 around the Ti wire 1 strengthens the bonding between the Ti wire 1 and the metal base material 2.

[0027] As a result, resistance welding is performed in a short time using a large current and pressure, making the Ti wire 1 less susceptible to heat effects and less likely to become embrittled. In addition, since the Ti wire 1 is joined to the metal base material 2 while being entirely covered with the Ni powder 3, the numerous Ni powders 3 block oxygen around the Ti wire 1 during welding, and the thermal diffusion of the Ti wire 1 through this Ni powder 3 suppresses the temperature rise of the Ti wire 1 and prevents its embrittlement.

[0028] Figure 10 shows the state in which multiple Ti wires 1 are joined together to a metal base material 2. In this case, the joining strength between the Ti wires 1 and the metal base material 2 is increased. After joining, each Ti wire 1 can be cut into individual pieces in the vertical direction, allowing for efficient production of single-wire joints.

[0029] As described above, the present invention uses resistance welding in the atmosphere with a large current and pressure in a short time, so the Ti wire (titanium material) 1 is less susceptible to heat effects and is less likely to become embrittled. In addition, the Ti wire (titanium material) 1 is joined to the metal base material while being entirely covered with Ni (nickel) powder 3. Therefore, during welding, the numerous Ni powder particles 3 have the effect of blocking oxygen around the Ti wire (titanium material) 1, and the Ti wire (titanium material) 1 is thermally diffused through this Ni powder 3. This suppresses the temperature rise of the Ti wire (titanium material) 1, preventing its embrittlement. This allows for easy and appropriate joining of the Ti wire (titanium material) 1 in a short time and at low cost.

[0030] In this embodiment, the Ti wire 1, which is a wire material, and the metal base material 2 are joined together, but this is not limitative, and a Ti material other than a wire material may also be joined together with a metal base material.

[0031] The present invention is not limited to the above-described embodiments, and various additions, modifications, and omissions are possible without departing from the spirit of the present invention. Therefore, such additions, modifications, and omissions are also included in the scope of the present invention. [Explanation of symbols]

[0032] 1: Ti wire (titanium material) 2: Metal base material 3: Ni (nickel) powder 4: Nickel base 5: Nickel immobilization 6: Multiple contact points between Ti wire 1 and Ni powder 3 7: Ni powder 3, multiple contact points between 3 10, 11: Welding electrodes 15: Welding power supply 20: Resistance welding equipment A: Welding current

Claims

1. 1. A method for joining a titanium or titanium-based alloy material to a metal substrate, comprising: The method for joining titanium or titanium-based alloy materials includes covering the entire titanium or titanium-based alloy material with nickel powder and resistance welding the titanium or titanium-based alloy material to the metal base material.

2. In claim 1, The method for joining titanium or titanium alloy materials, wherein the titanium or titanium alloy materials are wire materials.

3. In claim 1, a first step of placing nickel powder on the metal base material and resistance welding the powder to form a nickel undercoat covering the underside of the titanium or titanium alloy material; a second step of placing the titanium or titanium-based alloy material on the nickel undercoat and then placing nickel powder thereon to form a nickel overcoat covering the titanium or titanium-based alloy material; and a third step of integrating the upper and lower sides of the titanium or titanium-based alloy material by resistance welding in a state in which the upper and lower sides are entirely covered with the nickel powder by the first step and the second step.

4. In claim 3, In a third step, the nickel powder covering the titanium or titanium-based alloy material is also resistance-welded to each other.

5. In claim 2, A method of joining titanium or titanium-based alloy materials, wherein a plurality of wires of said titanium or titanium-based alloy material are joined together to a metal base material.

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