JP2015117423A - Aluminum alloy wire material, capacitor and manufacturing method of aluminum alloy wire material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy wire material having properties (strength, toughness and conductivity) suitable for a raw material of a capacitor terminal with a thread part in a good balance, a capacitor having a terminal containing the aluminum alloy wire material, and a manufacturing method of such an aluminum alloy wire material.SOLUTION: There is provided an aluminum alloy wire material used for a capacitor terminal with a thread part, having Fe of 0.25 mass% to 2.2 mass% inclusive, Mg of 0.05 mass% to 0.5 mass% inclusive and the balance Al with inevitable impurities, and conductivity of 55% IACS or more and breaking elongation of 10% or more.

Description

  The present invention relates to an aluminum (Al) alloy wire used for a capacitor terminal having a threaded portion, a capacitor including a terminal made of an Al alloy wire, and an Al alloy wire manufacturing method. In particular, the present invention relates to an Al alloy wire provided with a good balance of properties (strength, toughness, conductivity) suitable for capacitor terminals having a threaded portion.

  In recent years, due to the increase in environmental awareness, improvement in fuel efficiency of engine vehicles (for example, diesel vehicles and gasoline vehicles) that drive by driving an internal combustion engine has been promoted. In addition, electric vehicles (for example, hybrid vehicles, fuel cell vehicles, and electric vehicles) that are equipped with a battery and run by driving a motor with the electric power have been popularized.

  These engine vehicles and electric vehicles are being mounted with electric double layer capacitors (capacitors) in order to regenerate and use, for example, kinetic energy during deceleration as electric energy. In an engine vehicle, an electric double layer capacitor is used as a power source for driving a starter (including driving after a temporary stop of idling) and a power source for supplying various electric parts (for example, a lamp, an audio, an air conditioner, etc.) This is to save fuel by using it for back-up when idling stops. On the other hand, in an electric vehicle, the electric double layer capacitor shares the power supply for supplying the various electric components described above, thereby reducing the burden on the battery and improving the battery life.

  As the electric double layer capacitor mounted on an engine vehicle or an electric vehicle, a large capacitor is often used because of its usage. As this large electric double layer capacitor, a so-called screw terminal type electric double layer capacitor having a terminal having a threaded thread portion is generally used. The mechanical and electrical connection between the electric double layer capacitor and the external device (a mating member) is performed by tightening the connection portion with the external device to the screw portion of the terminal.

  As a technique related to a terminal provided in this screw terminal type electric double layer capacitor, for example, Patent Document 1 discloses a rivet in which a male screw portion is provided at a connection location with an external device. The rivet is made of pure Al when the rivet is used for an aluminum electrolytic capacitor.

JP 2006-060181 A

  The electric double layer capacitor placed at the place of vibration such as the above-mentioned vehicle needs to strongly tighten the connecting part of the mating member to the screw part of the terminal so that the mechanical and electrical connection with the mating member does not come off due to vibration. There is. However, since the terminal is made of pure Al as described above, the terminal is easily loosened when the connection portion is strongly tightened to the terminal. If the terminal is bent, the screw connection between the terminal and the connecting portion is easily loosened, and the mechanical and electrical connection between the capacitor and the mating member may be disconnected. On the other hand, if the tightening between the terminal and the connecting portion is adjusted to such an extent that the terminal does not sag, the terminal is prevented from being sag, but the screw connection between the terminal and the connecting portion is easily loosened by vibration.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide an Al alloy wire having a good balance of properties (strength, toughness, electrical conductivity) suitable for capacitor terminals having screw portions. It is in.

  Another object of the present invention is to provide a capacitor having a terminal made of the Al alloy wire.

  Another object of the present invention is to provide a method for producing the Al alloy wire.

  The Al alloy wire of the present invention is used for a capacitor terminal having a threaded portion. The Al alloy wire of the present invention contains Fe in an amount of 0.25 to 2.2% by mass, Mg in an amount of 0.05 to 0.5% by mass, with the balance being Al and inevitable impurities. Have The Al alloy wire of the present invention has a conductivity of 55% IACS or more and a breaking elongation of 10% or more.

  The capacitor of the present invention includes a terminal having a screw portion. This terminal is made of the Al alloy wire of the present invention.

  The method for producing an Al alloy wire according to the present invention comprises an casting process, a rolling process, a heat treatment process, and a wire drawing process, and produces an Al alloy wire used for a capacitor terminal having a threaded portion. The casting process includes an alloy of Fe containing 0.25 mass% to 2.2 mass% Fe, 0.05 mass% to 0.5 mass% Mg, and the balance of Al and inevitable impurities. The molten metal is cast to form a cast material. In the rolling step, the cast material is rolled to form a rolled material. In the heat treatment step, a heat treatment is performed on the rolled material to form a heat treatment material. In the wire drawing step, the heat treated material is drawn to form a wire drawing material.

  The Al alloy wire according to the present invention has characteristics (for example, strength, toughness, conductivity, etc.) suitable for a capacitor terminal having a threaded portion in a well-balanced manner.

  In the capacitor of the present invention, the mechanical and electrical connection with the mating member is difficult to be disconnected.

  The method for producing an Al alloy wire of the present invention can produce an Al alloy wire having characteristics (for example, strength, toughness, conductivity, etc.) suitable for a capacitor terminal having a threaded portion.

<< Description of Embodiments of the Present Invention >>
First, the contents of the embodiment of the present invention will be listed and described.

  (1) The Al alloy wire according to the embodiment is used for a capacitor terminal having a threaded portion. The Al alloy wire contains Fe in an amount of 0.25 to 2.2% by mass, Mg in an amount of 0.05 to 0.5% by mass, and the balance is composed of Al and inevitable impurities. The Al alloy wire has an electrical conductivity of 55% IACS or more and an elongation at break of 10% or more.

  According to the above configuration, since a suitable characteristic (for example, strength, toughness, conductivity, etc.) suitable for a capacitor terminal having a threaded portion is provided in a well-balanced manner, a screw terminal type electrolytic double layer capacitor (capacitor) terminal, etc. It can utilize suitably for the raw material of the capacitor terminal which has a part. Specifically, the Al alloy wire has a conductivity of 55% IACS or more, and has a high conductivity as the terminal. In addition, when the elongation at break is 10% or more, strong processing such as forging (forging) represented by plastic processing (header (former) processing) when forming a terminal having a screw portion using this Al alloy wire This is because cracks and the like are less likely to occur even if a cutting process is performed. Furthermore, compared to the case where the terminal is formed of pure Al alloy wire, the terminal is less likely to sag, and the connection portion of the mating member can be strongly tightened to the terminal. And since it is difficult to sag compared to a terminal made of a pure Al alloy wire, even if vibration is applied in a state where the connection portion is tightened to the terminal, the screw connection between the terminal and the connection portion is difficult to loosen. This is because the tightening state with the portion can be maintained over a long period of time.

  (2) As one form of the Al alloy wire, a 0.2% proof stress is 75 MPa or more.

  According to said structure, since the 0.2% yield strength is 75 MPa or more, the terminal which has a thread part is formed using this Al alloy wire, and the connection part of the other member is firmly clamped to the terminal at room temperature. The terminal is difficult to loosen. Therefore, the connection part can be strongly tightened to the terminal at room temperature. Since the terminal can hardly be loosened at room temperature, the connection part can be strongly tightened to the terminal, so even if vibration is applied at room temperature and with the connection part tightened to the terminal, the terminal and the connection part are screwed together. Is difficult to loosen, and the tightening state between the terminal and the connecting portion can be maintained over a long period of time.

(3) As one form of the Al alloy wire, a stress relaxation rate is 35% or more. The stress relaxation rate is a value obtained by {(δ ₀ −δ _t ) / δ ₀ } × 100. δ ₀ is a test member having a length of 70 mm made from an Al alloy wire (diameter 4 mm or more and 13 mm or less), in a cantilever beam in which one end side of the test member is a fixed end and the other end side of the test member is a free end. This is the displacement (deflection) of the free end with respect to the load before applying the load to the test member when a predetermined load is applied to the free end of the test member. δ _t is the displacement amount (deflection) of the free end with respect to the state before the load is applied to the test member after unloading after holding the state where the displacement amount of the free end of the test piece is δ ₀ at 150 ° C. for 10 hours. is there.

  According to said structure, even if the stress relaxation rate is 35% or more, even if it forms the terminal which has a screw part using this Al alloy wire, and fastens the connection part of the other party member to the terminal under high temperature, The terminal is difficult to loosen. Therefore, the connection portion can be strongly tightened to the terminal at a high temperature. Since the terminal can hardly be loosened at high temperatures, the connection portion can be strongly tightened to the terminal. Therefore, even if vibration is applied at high temperatures and with the connection portion tightened on the terminal, the screw connection between the terminal and the connection portion is possible. Is difficult to loosen, and the tightening state between the terminal and the connecting portion can be maintained over a long period of time.

  (4) As one form of the Al alloy wire, the tensile strength is 110 MPa or more and 230 MPa or less.

  According to the above configuration, when the tensile strength satisfies the above range, both high strength and high toughness can be achieved, and it is suitable for a capacitor terminal having a screw portion such as a terminal of a screw terminal type electrolytic double layer capacitor. Available.

  (5) As one form of the Al alloy wire, it may further contain 0.005 mass% or more and 1.0 mass% or less of one or more additive elements selected from Si, Cu, and Mn. .

  According to said structure, high intensity | strength and high toughness can be made compatible, suppressing the fall of electrical conductivity. By making the total content 0.005% by mass or more, the strength can be improved, and by making the total content 1.0% by mass or less, a decrease in conductivity is suppressed. This is because the strength does not become too high and a decrease in toughness can be suppressed.

  (6) As one form of the Al alloy wire, at least one of Ti and B is further contained, the Ti content is 0.05% by mass or less, and the B content is 0.005% by mass or less. There are some.

  According to said structure, high intensity | strength and high toughness can be made compatible, suppressing the fall of electrical conductivity. By containing at least one of Ti with a content of 0.05% by mass or less and B with a content of 0.005% by mass or less, the decrease in electrical conductivity can be suppressed and the strength is improved while increasing. This is because the decrease in toughness can be suppressed.

  (7) The capacitor according to the embodiment includes a terminal having a screw portion. And a terminal uses the Al alloy wire as described in any one of the said embodiment (1)-(6) as a raw material.

  According to said structure, it is hard to disconnect mechanical and electrical connection with the other party member. By forming the terminal having the threaded portion using the above-described Al alloy wire, the terminal is difficult to sag, so that the connection portion of the mating member can be strongly tightened to the terminal. In addition, even if vibration is applied to the terminal with the connection portion tightened, the screw connection between the terminal and the connection portion is difficult to loosen, and the tightening state between the terminal and the connection portion can be maintained for a long time. is there. Therefore, it can be suitably used for various power sources mounted in places where vibration is applied, such as the above-described engine vehicles and electric vehicles.

  (8) The manufacturing method of the Al alloy wire according to the embodiment includes an casting process, a rolling process, a heat treatment process, and a wire drawing process, and manufactures an Al alloy wire used for a capacitor terminal having a screw portion. The casting process includes an alloy of Fe containing 0.25 mass% to 2.2 mass% Fe, 0.05 mass% to 0.5 mass% Mg, and the balance of Al and inevitable impurities. The molten metal is cast to form a cast material. In the rolling step, the cast material is rolled to form a rolled material. In the heat treatment step, the rolled material is subjected to a heat treatment to form a heat treated material in which Fe is precipitated. In the wire drawing step, the heat treated material is drawn to form a wire drawing material.

  According to the above configuration, an Al alloy wire having characteristics (for example, strength, toughness, conductivity, etc.) suitable for a capacitor terminal having a screw portion such as a screw terminal type electric double layer capacitor (capacitor) terminal is manufactured. it can. By providing a heat treatment step between the rolling step and the wire drawing step, Fe uniformly precipitated in the rolling step is precipitated, and the precipitation state of the Fe is in a good state (fine and uniformly dispersed state). This is because there is a possibility that Fe can be easily re-dissolved in the subsequent wire drawing step.

<< Details of Embodiment of the Present Invention >>
Details of the embodiment of the present invention will be described below. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to a claim are included.

[Aluminum alloy wire]
The main feature of the Al alloy wire according to the embodiment is that it has specific characteristics with specific contents of iron (Fe) and magnesium (Mg), and is a screw terminal type electric double layer capacitor (capacitor). It exists in the point which can utilize suitably for the capacitor terminal which has a screw part, such as a terminal.

[composition]
(Fe, Mg)
The Al alloy wire contains 0.25% by mass to 2.2% by mass of Fe and 0.05% by mass to 0.5% by mass of Mg. By containing 0.25 mass% or more of Fe, strength can be improved. On the other hand, by making Fe 2.2 mass% or less, while ensuring the electrical conductivity desired for a terminal, the plastic workability desired for the process of a terminal is securable. As for content of Fe, 0.9 mass% or more and 2.0 mass% or less are more preferable. Moreover, an intensity | strength can be improved because Mg shall be 0.05 mass% or more. On the other hand, by setting the Mg content to 0.5 mass% or less, it is easy to ensure electrical conductivity and toughness. The effect of improving the strength by containing Mg can be more exhibited when silicon (Si) described later is contained at the same time.

(Si, Cu, Mn)
The Al alloy wire preferably further contains one or more additive elements selected from Si, copper (Cu), and manganese (Mn). If it does so, it has high toughness while having higher strength, and it is excellent in plastic workability. Si and Cu have little decrease in conductivity and can improve strength. Although Mn has a great influence on the decrease in conductivity, the effect of improving the strength is high. These additive elements preferably have a total content of 0.005% by mass or more and 1.0% by mass or less, and particularly preferably 0.05% by mass or more and 0.5% by mass or less. The Si content is preferably 0.05% by mass or more and 0.3% by mass or less, and particularly preferably 0.05% by mass or more and 0.2% by mass or less. The Cu content is preferably 0.05% by mass or more and 0.5% by mass or less, and particularly preferably 0.05% by mass or more and 0.4% by mass or less. The Mn content is preferably 0.005% by mass or more and 0.2% by mass or less, particularly preferably 0.005% by mass or more and 0.15% by mass or less.

(Ti, B)
The Al alloy wire preferably further contains at least one of titanium (Ti) and boron (B). If it does so, high intensity | strength and high toughness can be made compatible, suppressing the fall of electrical conductivity. Ti and B have the effect of making the crystal structure of the Al alloy fine during casting. If the crystal structure is fine, the strength can be improved. Although the content of B alone may be sufficient, the effect of refining the crystal structure is further improved when Ti alone, particularly both, is contained. When Ti or B is contained too much, the above-mentioned refinement effect is saturated or the conductivity is lowered. Therefore, it is preferable that the Ti content is 0.05% by mass or less and the B content is 0.005% by mass or less. If it does so, the said refinement | miniaturization effect is fully easy to be acquired, without electrical conductivity falling. The lower limit of the Ti content is preferably 0.005% by mass or more, particularly preferably 0.01% by mass or more, and the lower limit of the B content is preferably 0.001% by mass or more.

(Other additive elements)
In addition, one or more additive elements selected from zinc (Zn), nickel (Ni), silver (Ag), chromium (Cr), and zirconium (Zr) can also be contained. By doing so, it is possible to improve strength, toughness, impact resistance and the like. These additive elements preferably have a total content of 0.005 mass% to 0.2 mass%, particularly preferably 0.005 mass% to 0.15 mass%.

[Characteristic]
Al alloy wire has high electrical conductivity and high toughness. Specifically, the conductivity is 55% IACS or more and the elongation at break is 10% or more. When the electrical conductivity is 55% IACS or more, it can be suitably used for a terminal having a screw portion such as a terminal of a screw terminal type electrolytic double layer capacitor (capacitor). In addition, when the elongation at break is 10% or more, strong processing such as forging (forging) represented by plastic processing (header (former) processing) when forming a terminal having a screw portion using this Al alloy wire , Rolling, etc.) and cracking are less likely to occur. Therefore, it can utilize suitably for the terminal which has screw parts, such as a terminal of a screw terminal type electrolytic double layer capacitor.

  The tensile strength of the Al alloy wire is preferably 110 MPa or more and 230 MPa or less. The present inventors have found that an Al alloy wire having only high strength and poor toughness is not suitable for a terminal having a screw portion such as a terminal of a screw terminal type electric double layer capacitor. In general, an increase in strength causes a decrease in toughness. When the tensile strength satisfies the above range, both high toughness and high strength can be achieved. The tensile strength of the Al alloy wire is more preferably 140 MPa or more and 210 MPa or less.

  The 0.2% yield strength of the Al alloy wire is preferably 75 MPa or more. When the 0.2% proof stress is higher, a terminal having a threaded portion is formed using an Al alloy wire, and the terminal is less likely to sag even if the connecting portion of the mating member is strongly tightened to the terminal at room temperature. Therefore, the connection portion can be strongly tightened to the terminal. In addition, since the terminal is difficult to sag and the connection part can be strongly tightened to the terminal, even if vibration is applied with the connection part tightened to the terminal, the screw connection between the terminal and the connection part is difficult to loosen. And the tightening state with the connection part can be maintained for a long time. The 0.2% yield strength of the Al alloy wire is more preferably 80 MPa or more, and particularly preferably 90 MPa or more. These effects are more significant when the 0.2% proof stress is higher when the tensile strength is the same.

The stress relaxation rate of the Al alloy wire is preferably 35% or more. The stress relaxation rate (%) is obtained by {(δ ₀ −δ _t ) / δ ₀ } × 100. δ ₀ is a test member having a length of 70 mm made from an Al alloy wire (diameter 4 mm or more and 13 mm or less), in a cantilever beam in which one end side of the test member is a fixed end and the other end side of the test member is a free end. This is the displacement (deflection) of the free end with respect to the load before applying the load to the test member when a predetermined load is applied to the free end of the test member. δ _t is the amount of displacement of the free end relative to the amount before the load is applied to the test member after unloading after holding the state where the displacement amount (deflection) of the free end of the test piece is δ ₀ at 150 ° C. for 10 hours. Deflection). The higher the stress relaxation rate is, the more difficult it is to sag even if a terminal having a thread portion is formed using an Al alloy wire and the connecting portion of the mating member is strongly tightened to the terminal at a high temperature. Therefore, the connection portion can be strongly tightened to the terminal at a high temperature. In addition, since the terminal is difficult to sag at high temperatures, the connection portion can be strongly tightened to the terminal. Therefore, even if vibration is applied at a high temperature and the connection portion is tightened to the terminal, the screw between the terminal and the connection portion The connection is difficult to loosen, and the tightening state between the terminal and the connecting portion can be maintained over a long period of time. The stress relaxation rate of the Al alloy wire is more preferably 40% or more, and particularly preferably 55% or more.

  By adjusting additive elements (type and content), manufacturing conditions (heat treatment conditions (especially when heat treatment is performed), degree of work in the process before and after heat treatment, total work degree, etc. (details will be described later)) Thus, an Al alloy wire satisfying the specific ranges described above can be obtained, such as conductivity, elongation at break, tensile strength, 0.2% proof stress, and stress relaxation rate. For example, when the additive element is reduced or the temperature lowering rate is lowered after increasing the heating temperature during the heat treatment, the conductivity and toughness tend to increase. On the other hand, when the additive element is increased or the heating temperature during heat treatment is lowered, the strength and the 0.2% proof stress tend to increase. In addition, when heat treatment is performed after wire rolling and before wire drawing, Fe that is uniformly dissolved in the rolling process can be precipitated and the precipitates of Fe can be finely and evenly dispersed, so that the electrical conductivity, strength, and toughness can be excellent. High nature. When the workability of the wire drawing performed after heat treatment is increased, there is a high possibility of re-solidifying Fe by increasing the surface area of Fe by making Fe finer in the heat treatment process, and strength, toughness, 0.2% proof stress Likely to be higher.

[Shape / Size]
The cross-sectional shape of the Al alloy wire can have various shapes depending on the die shape during wire drawing in the manufacturing method described later. The cross-sectional shape is not particularly limited, but a circular shape is typical. In addition, examples of the cross-sectional shape include an elliptical shape and a polygonal shape such as a rectangle or a hexagon. The wire diameter (diameter) of the Al alloy wire can be set to various wire diameters (diameters) by appropriately adjusting the degree of processing (cross-sectional reduction rate) during wire drawing. For example, when used for a terminal of a screw terminal type electric double layer capacitor, the wire diameter of the Al alloy wire is preferably 5 mm or more and 15 mm or less.

[Method for producing aluminum alloy wire]
The method for producing an Al alloy wire includes the following casting process, rolling process, heat treatment process, and wire drawing process.

[Casting process]
In the casting step, a molten metal made of the Al alloy having the specific composition is cast to form a cast material made of the Al alloy having the specific composition. By setting it as the casting material which consists of the said specific plastic alloy, it can make it hard to disconnect at a post process (for example, at the time of wire drawing).

  For casting, either continuous casting using a movable mold or a frame-shaped fixed mold, or mold casting (billet casting) using a box-shaped fixed mold can be used. In continuous casting, since the molten metal can be rapidly solidified, a cast material having a fine crystal structure can be obtained. In addition, by rapid solidification, the crystal precipitate can be made fine, and a cast material having a structure in which the fine crystal precipitate is uniformly dispersed is obtained. When such a cast material is used as a raw material, it is easy to produce an Al alloy wire having a fine crystal structure, and it is possible to improve the strength by refining the crystal and toughness by dispersing fine crystal precipitates. .

  Although a cooling rate can be selected suitably, 1 degree-C / sec or more is preferable and 4 degree-C / sec or more is more preferable. Further, it is more preferable that the cooling rate is 20 ° C./sec or more in the solid-liquid coexisting temperature range of the molten metal at 600 to 700 ° C. For example, when a continuous casting machine having a water-cooled copper mold or a forced water cooling mechanism is used, rapid solidification at the cooling rate as described above can be realized. By performing the rapid solidification by adjusting the cooling rate in continuous casting, DAS (Dendrite Arm Spacing) of the cast material obtained after casting can be reduced. DAS is preferably 50 μm or less, and more preferably 40 μm or less.

  When adding Ti or B to the molten metal, it is preferable to add Ti or B immediately before pouring the molten metal into the mold. Then, local sedimentation of Ti or the like can be suppressed, and a cast material in which Ti or the like is uniformly mixed can be manufactured.

[Rolling process]
In the rolling step, the cast material is subjected to (hot) rolling to form a rolled material. The casting process and the rolling process are preferably performed continuously. If it does so, hot rolling can be easily performed using the heat | fever accumulate | stored in a casting material, energy efficiency is good, and it is excellent in the productivity of a cast rolling material compared with a batch type casting method. By this rolling, Fe can be uniformly dissolved.

[Preliminary drawing process]
In the preliminary wire drawing step, a skin wire drawing process can be performed on the rolled material to form a preliminary wire drawing material. The preliminary wire drawing step can be performed as necessary. The degree of processing of this preliminary drawing (= -ln (cross-sectional area after skin pass drawing / cross-sectional area before skin pass drawing)) is smaller than the degree of drawing described later, for example, about 0.3 or less. Can be mentioned.

[Heat treatment process]
In the heat treatment step, the rolled material (preliminary wire drawing material) is heat treated to form a heat treated material. This heat treatment is performed to improve the crystalline state (Fe precipitation amount, precipitation state, solid solution amount, solid solution state, etc.) of the rolled material (preliminary wire drawing material). Specifically, Fe uniformly dissolved in the rolling step is precipitated, and the precipitation state of Fe is set to a good state (a fine and substantially uniformly dispersed state). When the heat treatment material in which the precipitates of Fe are finely and substantially uniformly dispersed is used as a raw material, the precipitated Fe can be easily re-dissolved by wire drawing, and mechanical properties (for example, 0.2% proof stress, stress relaxation rate) It is easy to produce an Al alloy wire excellent in

For the heat treatment, batch processing can be used. The atmosphere during the heat treatment is preferably an atmosphere having a low oxygen content, such as an air atmosphere or a non-oxidizing atmosphere, in order to suppress the formation of an oxide film on the surface of the wire due to heat during the treatment. The non-oxidizing atmosphere is, for example, a vacuum atmosphere (reduced pressure atmosphere), an inert gas atmosphere such as nitrogen (N ₂ ) or argon (Ar), a hydrogen-containing gas (for example, hydrogen (H ₂ ) only, N ₂ , Ar, A reducing gas such as a mixed gas of an inert gas such as helium (He) and hydrogen (H ₂ ) or a carbon dioxide-containing gas (eg, a mixed gas of carbon monoxide (CO) and carbon dioxide (CO ₂ )). The atmosphere can be mentioned.

  Batch processing (bright heat treatment) is a processing method in which a heating target is enclosed in a heating container (atmosphere furnace, for example, a box-type furnace), and the heating process is limited. This is a processing method that makes it easy to manage the heating state. In the batch treatment, the breaking elongation of the wire can be increased to 10% or more by setting the heating temperature to 250 ° C. or higher. Preferred conditions are a heating temperature of 300 ° C. or more and 500 ° C. or less, and a holding time of 0.5 hours or more and 6 hours or less. By setting the heating temperature to 250 ° C. or higher or the holding time to 0.5 hour or longer, in addition to improving toughness, the conductivity can be improved. By setting the heating temperature to 500 ° C. or less or the holding time to 6 hours or less, a decrease in strength can be suppressed. In batch processing, the cooling rate from the heating temperature, that is, the cooling rate after heating is preferably 50 ° C./sec or less. A relatively large amount of fine precipitates can be precipitated by slowing down the temperature decreasing rate relatively slowly. The temperature-decreasing rate can be achieved, for example, by not leaving the furnace immediately after the heating, but by continuously storing it in the furnace after the heating.

[Drawing process]
The heat treatment material is subjected to (cold) wire drawing to form a wire drawing material. The degree of wire drawing (= -ln (cross-sectional area after drawing / cross-sectional area before drawing)) can be appropriately selected according to the desired wire diameter. The drawing degree is preferably larger than the degree of drawing in the preliminary drawing step. For example, the ratio of the drawing degree to the preliminary drawing degree (drawing degree / preliminary drawing degree) is more than 1.0, 1.1 or more, and further 1.2 or more. . The upper limit of this ratio is about 30. Heat treatment is performed before the wire drawing process to finely and substantially uniformly disperse the Fe precipitates. Therefore, by increasing the degree of processing in the wire drawing process, precipitation is performed even when the wire drawing is performed cold. It is possible to easily re-dissolve Fe that has been dissolved. Thereby, an Al alloy wire excellent in mechanical properties (for example, 0.2% yield strength, stress relaxation rate) is easily obtained. It is preferable to form a wire drawing material satisfying H14 or H16 defined in “Aluminum, magnesium and alloys thereof-categorized symbols JIS H 0001 (1998)” by appropriately adjusting the degree of wire drawing.

[Softening process]
A softening treatment can be performed on the wire drawing material. This softening treatment softens the wire rod, which has been increased by refining the crystal structure and work hardening, without significantly reducing the strength, thereby increasing the toughness of the wire rod. A softening process can be performed as needed. The conditions for the softening treatment may be the same as the heat treatment conditions described above. Even if this softening treatment is not performed, the elongation at break satisfies 10% or more depending on the diameter (thickness) of the wire drawing material. For example, when the diameter is large (that is, when the degree of wire drawing is small), the toughness is not significantly reduced by work hardening, and the elongation at break of the wire drawing material may be 10% or more. On the other hand, there may be a case where the elongation at break of the wire drawing material is less than 10%. In this case, the softening treatment may be performed under such a condition that the elongation of the wire after the softening treatment is 10% or more. Of course, even when the elongation at break satisfies 10% or more, when increasing the elongation at break, a softening treatment for improving toughness may be performed.

[Capacitor]
The capacitor includes a terminal that is mechanically and electrically connected to an external device. This terminal is made of the above-described Al alloy wire, and has at least one screw portion of a male screw portion formed by male screw processing and a female screw portion formed by female screw processing. A terminal having a male screw portion can be manufactured through the following process, for example. First, a blank wire obtained by cutting the above-described Al alloy wire into an appropriate length is prepared. Next, the blank blank is subjected to header processing (forging) to produce a screw blank having a screw shaft. Then, a thread groove is formed by rolling or cutting the shaft portion. On the other hand, the manufacture of the terminal having the female screw portion can be performed through the following process, for example. First, the prepared Al alloy wire is introduced into the nut former. The introduced Al alloy wire is cut into an appropriate length to produce a cut piece. Next, a hole that becomes a screw hole is formed in the cut piece by forging to produce a nut blank. And a thread groove is shape | molded in the internal peripheral surface of the said hole using a tapping machine. For the manufacture of the terminal having both the male screw part and the female screw part, a blank wire is prepared in the same manner as described above, and the male screw part and the female screw part are respectively provided on one end side and the other end side of the blank wire material in the same manner as described above. This can be done by forming. For example, first, the shaft portion and the hole are formed in each of one end side and the other end side of the blank wire. And after forming an internal thread groove in the internal peripheral surface of the said hole, forming an external thread groove in the said axial part is mentioned.

[Function and effect]
According to the above-described Al alloy wire, since it has the above-mentioned specific composition and specific characteristics (conductivity, elongation at break, tensile strength, 0.2% proof stress, stress relaxation rate), the screw terminal type It can utilize suitably for the capacitor terminal which has a thread part, such as the terminal of an electrolytic double layer capacitor (capacitor).

  According to the above-described method for producing an Al alloy wire, an Al alloy wire suitable for a capacitor terminal having a screw portion, such as a screw terminal type electrolytic double layer capacitor (capacitor) terminal, can be produced. In particular, by providing a heat treatment step between the rolling step and the wire drawing step, it is easy to obtain an Al alloy wire excellent in mechanical properties (for example, 0.2% yield strength and stress relaxation rate).

  According to the above-described capacitor, since the mechanical and electrical connection with the mating member of the capacitor is difficult to be removed by providing the terminal made of the above-described Al alloy wire, the portion to which vibration is particularly added (for example, the above-mentioned It can be suitably used for various power sources mounted on engine vehicles and electric vehicles.

《Test example》
An Al alloy wire was prepared, and various characteristics of the Al alloy wire were examined. Here, the Al alloy wire was produced by the procedure of casting → rolling → preliminary drawing → heat treatment → drawing.

First, pure Al (99.7 mass% or more Al) was prepared and melted as a base, and the additive elements shown in Table 1 were added to the obtained molten metal (molten Al) so as to have the contents shown in Table 1. Then, an Al alloy melt is prepared. It is desirable that the Al alloy molten metal whose components have been adjusted is appropriately subjected to hydrogen gas removal treatment or foreign matter removal treatment. Incidentally, Ti, or samples containing Ti and B, so that the content shown in Table 1 was fed Ti particles or TiB ₂ wire to molten Al alloy immediately before casting.

Next, using a belt-wheel type continuous casting and rolling machine, the prepared Al alloy molten metal is continuously cast and hot-rolled, and a wire rod having a wire diameter φ _r of 8 mm to 18 mm (continuous cast rolled material). Was made. In the continuous casting, the cooling rate was adjusted to 4.5 ° C./sec by adjusting the cooling mechanism and the like.

Preliminary wire drawing (skin pass wire drawing) was applied to the obtained wire rod to prepare a predrawn wire material having a wire diameter φ _p (mm) shown in Table 1. Sample 6 and sample 102 in which the wire diameter φ _{r of the} wire rod and the wire diameter φ _p of the pre-drawing material are the same size were not subjected to pre-drawing.

  Heat treatment was performed on the pre-drawn wire or the wire rod by heat treatment. Here, the heat treatment was performed by batch processing using a box furnace at the atmosphere, heating temperature, holding time, and temperature decreasing rate shown in Table 1.

The heat treatment material was subjected to cold wire drawing to produce a wire drawing material (Al alloy wire) having a wire diameter φ _d (mm) shown in Table 1.

  The obtained Al alloy wire was measured for tensile strength (MPa), 0.2% yield strength (MPa), elongation at break (%), conductivity (% IACS), and stress relaxation rate (%). The results are shown in Table 2.

Tensile strength (MPa), 0.2% proof stress (MPa), and elongation at break (%) were measured using a general-purpose tensile tester in accordance with “Metal Material Tensile Test Method JIS Z 2241 (2011)”. It was measured. The conductivity (% IACS) was measured by the bridge method. The stress relaxation rate (%) was determined by {(δ ₀ −δ _t ) / δ ₀ } × 100. δ ₀ is a cantilever beam in which a test member having a length of 70 mm is prepared from each Al alloy wire, one end of the test member is a fixed end, and the other end of the test member is a free end. This is the displacement (deflection) of the free end with respect to the load before the load is applied to the test member when a predetermined load is applied. δ _t is the amount of displacement of the free end relative to the amount before the load is applied to the test member after unloading after holding the state where the displacement amount (deflection) of the free end of the test piece is δ ₀ at 150 ° C. for 10 hours. Deflection). Here, the deflection δ ₀ was set to 25 mm.

  Sample Nos. Containing specific amounts of Fe and Mg respectively. 1 to Sample No. No. 6, as shown in Table 2, the electrical conductivity is 55% or more, the elongation at break is 10% or more, the tensile strength is 110 MPa or more and 230 MPa or less, the 0.2% proof stress is 75 MPa or more, the stress relaxation The rate is 35% or more.

  From this result, sample no. 1 to Sample No. It is considered that the Al alloy wire No. 6 can be suitably used for a capacitor terminal having a screw portion such as a screw terminal type electric double layer capacitor (capacitor). In particular, sample no. 1 to Sample No. It is considered that the terminal is difficult to sag even if a terminal having a thread portion is formed using the Al alloy wire of No. 6 and the connecting portion of the mating member is strongly tightened to the terminal under any condition of normal temperature or high temperature. . These sample Nos. 1 to Sample No. This is because the Al alloy wire No. 6 has a 0.2% proof stress of 75 MPa or more and a stress relaxation rate of 35% or more. Therefore, even in the same situation, the connection portion can be strongly tightened to the terminal. In addition, even if vibration is applied to the terminal with the connection portion tightened, the tightening state between the terminal and the connection portion is difficult to loosen, and the tightening state between the terminal and the connection portion can be maintained for a long time. .

  These sample Nos. 1 to Sample No. The electrical conductivity of 6 is 55% or more, the elongation at break is 10% or more, the tensile strength is 110 MPa or more and 230 MPa or less, the 0.2% proof stress is 75 MPa or more, and the stress relaxation rate is 35% or more. The following points can be considered as reasons for this. (1) Since heat treatment was performed before wire drawing after rolling, there is a high possibility that the amount of precipitated Fe could be adjusted (maintained), that is, the amount of solid solution of Fe could be adjusted (maintained). (2) Since the degree of processing of the wire drawing performed after the heat treatment is increased, there is a high possibility that Fe is re-dissolved.

  Sample No. Although 101 has high elongation at break and electrical conductivity, it has low tensile strength, 0.2% proof stress, and stress relaxation rate. Sample No. 101, sample No. 1 to Sample No. On the other hand, since it does not contain Mg and has a composition corresponding to pure Al, it is considered that the tensile strength, 0.2% proof stress, and stress relaxation rate were lowered. That is, sample no. If the capacitor terminal having the above-described screw portion is formed using a wire material equivalent to 101 pure Al, and the connection portion of the mating member is strongly tightened to the terminal, it is considered that the terminal is likely to sag. Therefore, sample no. 101 is unsuitable for the capacitor terminal having the above-described screw portion.

  Sample No. No. 102 has high elongation at break, 0.2% proof stress, and stress relaxation rate, but low conductivity. Sample No. 102, sample No. 1 to Sample No. Compared to 6, the Mg content is high and the Si content is also high, so the electrical conductivity is considered to be low. Therefore, sample no. It can be seen that the Al alloy wire No. 102 is unsuitable for the capacitor terminal material having the above-described screw portion.

  Sample No. 103 has high tensile strength, 0.2% proof stress, and stress relaxation rate, but has low elongation at break and electrical conductivity. Sample No. 103, sample No. 1 to Sample No. It is considered that the elongation at break and the electrical conductivity were low because the Fe content was higher than that of 6. That is, sample no. Since the Al alloy wire No. 103 has a small elongation at break and poor plastic workability, it is considered that cracks and the like are likely to occur when plastic working is performed when forming the capacitor terminal. In addition, the conductivity is low as described above. Therefore, sample no. 103 is unsuitable for the material of the capacitor terminal having the above-described screw portion.

  Sample No. Although 104 has high tensile strength, electrical conductivity, and stress relaxation rate, it has low 0.2% yield strength and elongation at break. Sample No. 104, sample No. 1 to Sample No. Compared to 6, the heat treatment temperature was lower, so the 0.2% yield strength and elongation at break were considered to be lower. That is, sample no. Since the Al alloy wire No. 104 has a small elongation at break and poor plastic workability, it is considered that cracks and other defects are likely to occur when plastic processing is performed when forming the capacitor terminals. In addition, since the 0.2% proof stress is low, it is considered that the capacitor terminal having the above-described screw portion is formed using this wire, and the terminal is easily sagged when the connection portion of the mating member is strongly tightened to the terminal. Therefore, sample no. 104 is unsuitable for the capacitor terminal having the above-described screw portion.

  The aluminum alloy wire of the present invention can be suitably used for a terminal of an electric storage device such as a screw terminal type electric double layer capacitor (capacitor) mounted on an engine vehicle or an electric vehicle. The capacitor of the present invention can be suitably used for various power sources mounted on engine vehicles, electric vehicles, and the like. In addition, the capacitor of the present invention can also be suitably used for various power sources mounted on railway vehicles. The manufacturing method of the aluminum alloy wire of the present invention can be suitably used for manufacturing the aluminum alloy wire of the present invention.

Claims (8)

Fe containing 0.25 mass% or more and 2.2 mass% or less, Mg containing 0.05 mass% or more and 0.5 mass% or less, with the balance being composed of Al and inevitable impurities,
Conductivity is 55% IACS or higher,
The elongation at break is 10% or more,
An aluminum alloy wire used for a capacitor terminal having a threaded portion.   The aluminum alloy wire according to claim 1, wherein the 0.2% proof stress is 75 MPa or more.   The aluminum alloy wire according to claim 1 or 2, wherein the stress relaxation rate is 35% or more.   The aluminum alloy wire according to any one of claims 1 to 3, wherein the tensile strength is 110 MPa or more and 230 MPa or less.   Furthermore, the aluminum of any one of Claims 1-4 which contains 0.005 mass% or more and 1.0 mass% or less of 1 or more types of additional elements selected from Si, Cu, and Mn in total. Alloy wire. Furthermore, containing at least one of Ti and B,
The aluminum alloy wire according to any one of claims 1 to 5, wherein the Ti content is 0.05% by mass or less, and the B content is 0.005% by mass or less. A capacitor including a terminal having a screw portion,
The capacitor is made from the aluminum alloy wire according to claim 1. Casting a molten aluminum alloy containing Fe in a range of 0.25% to 2.2% by weight, Mg in a range of 0.05% to 0.5% by weight, and the balance consisting of Al and inevitable impurities Casting process to form a cast material,
A rolling step of rolling the cast material to form a rolled material;
A heat treatment step of heat treating the rolled material to form a heat treated material in which Fe is deposited;
A wire drawing step of forming a wire drawing material by subjecting the heat treatment material to wire drawing,
An aluminum alloy wire manufacturing method for manufacturing an aluminum alloy wire used for a capacitor terminal having a threaded portion.