WO2022249665A1 - Aluminum alloy, aluminum alloy wire, and method for manufacturing aluminum alloy wire - Google Patents

Abstract

This aluminum alloy has a composition containing 0.6-1.5 mass% of silicon, 0.5-1.3 mass% of magnesium, 0.3-1.2 (exclusive of 0.3) mass% of copper, and 0.2-1.15 mass% of manganese, with the remainder consisting of aluminum and inevitable impurities, wherein the abundance ratio of subgrain boundaries, as determined through crystal analysis of the cross section of the aluminum alloy, which has been subjected to a solution heat treatment and an aging treatment, by means of the SEM-EBSD method, is at least 15%.

Description

Aluminum alloy, aluminum alloy wire, and method for producing aluminum alloy wire

The present disclosure relates to aluminum alloys, aluminum alloy wires, and methods of manufacturing aluminum alloy wires.
This application claims priority based on Japanese Patent Application No. 2021-089505 filed in Japan on May 27, 2021, and incorporates all the content described in the Japanese application.

Patent Document 1 discloses an aluminum alloy wire made of an aluminum alloy containing silicon and magnesium and having high tensile strength after solution treatment and aging treatment. The above aluminum alloy wire can be used as a raw material for aluminum alloy members. The aluminum alloy member is manufactured by subjecting the aluminum alloy wire to predetermined plastic working, followed by solution treatment and aging treatment.

JP 2015-124409 A

The aluminum alloy of the present disclosure contains 0.6% to 1.5% by mass of silicon, 0.5% to 1.3% by mass of magnesium, and more than 0.3% by mass to 1.2% by mass of copper. Hereinafter, the composition includes 0.2% by mass or more and 1.15% by mass or less of manganese, and the balance is aluminum and unavoidable impurities. The existence ratio of subgrain boundaries obtained by crystallographic analysis of a cross section by the SEM-EBSD method in the state of being subjected to solution treatment and aging treatment is 15% or more.
The SEM-EBSD method is a crystal orientation analysis method using a scanning electron microscope (SEM) and an electron back scattering diffraction pattern (EBSD pattern).

The aluminum alloy wire of the present disclosure is made of the aluminum alloy of the present disclosure.

The method for producing an aluminum alloy wire of the present disclosure contains silicon in an amount of 0.6% by mass or more and 1.5% by mass or less, magnesium in an amount of 0.5% by mass or more and 1.3% by mass or less, and copper in an amount of more than 0.3% by mass1. .2% by mass or less, containing 0.2% by mass or more and 1.15% by mass or less of manganese, and the balance being aluminum and unavoidable impurities. a step of producing a first softened material by subjecting the hot-worked material to a first softening treatment; and a process of subjecting the first softened material to a first cold drawing process to obtain a first a step of manufacturing a first drawn wire material; a step of subjecting the first drawn wire material to a second softening treatment to manufacture a second softened material; and a second cold drawing process performed on the second softened material. and a step of manufacturing a second wire drawn material. The heating temperature of the first softening treatment and the second softening treatment is 300°C or higher and lower than 500°C. The working ratio of the first wire drawing is 30% or more. The working ratio of the second wire drawing is 20% or more.

FIG. 1 is a perspective view showing an example of an aluminum alloy wire of an embodiment. FIG. 2 is a schematic diagram illustrating the process of forming a structure containing subgrain boundaries in an aluminum alloy. FIG. 3 is a schematic diagram illustrating the process of forming a structure containing subgrain boundaries in an aluminum alloy.

[Problems to be Solved by the Present Disclosure]
As described above, it is desired that aluminum alloy members used after solution treatment and aging treatment have excellent creep properties. Further, an aluminum alloy is desired that can constitute an aluminum alloy member having excellent creep properties.

The aluminum alloy wire described in Patent Document 1 has a high tensile strength after a heat resistance test in a state of solution treatment and aging treatment. If such an aluminum alloy wire is used as a raw material for an aluminum alloy member, an aluminum alloy member having high tensile strength even when used at high temperatures can be obtained. However, conventionally, no mention has been made of an aluminum alloy wire from which an aluminum alloy member having excellent creep properties can be obtained.

Therefore, one of the objects of the present disclosure is to provide an aluminum alloy that has excellent creep properties in a state of being subjected to solution treatment and aging treatment. Another object of the present disclosure is to provide an aluminum alloy wire made of the above aluminum alloy. Another object of the present disclosure is to provide an aluminum alloy wire manufacturing method capable of manufacturing the aluminum alloy wire described above.

[Effect of the present disclosure]
The aluminum alloy of the present disclosure and the aluminum alloy wire of the present disclosure have excellent creep properties in the state of solution heat treatment and aging treatment. The aluminum alloy wire manufacturing method of the present disclosure can manufacture the aluminum alloy wire of the present disclosure.

[Description of Embodiments of the Present Disclosure]
First, the embodiments of the present disclosure are listed and described.
(1) The aluminum alloy according to one aspect of the present disclosure contains 0.6% by mass or more and 1.5% by mass or less of silicon, 0.5% by mass or more and 1.3% by mass or less of magnesium, and 0.3% by mass of copper. % and 1.2% by mass or less, 0.2% by mass or more and 1.15% by mass or less of manganese, and the balance being aluminum and unavoidable impurities. In this aluminum alloy, the existence ratio of subgrain boundaries obtained by crystallographic analysis of the cross section by the SEM-EBSD method in the state of being subjected to solution treatment and aging treatment is 15% or more.

A subgrain boundary in the present disclosure means a grain boundary existing between adjacent crystal grains having a crystal orientation difference of 2° or more and 15° or less. In the present disclosure, a grain boundary existing between adjacent crystal grains having a crystal orientation difference of more than 15° and less than or equal to 180° is called a large-angle boundary. The existence ratio of subgrain boundaries in the present disclosure is the ratio of the length of subgrain boundaries to the total length of the length of subgrain boundaries and the length of large-angle boundaries in a cross section of an aluminum alloy. A method for measuring the length of the subgrain boundary and the length of the large angle boundary will be described later.
In the present disclosure, the cross section of the aluminum alloy is, for example, the following cross sections. When the aluminum alloy has a somewhat long shape such as a wire, pipe, plate, etc., the cross section is taken along a plane along the longitudinal direction of the aluminum alloy.
In the present disclosure, the conditions for the solution treatment and the conditions for the aging treatment are as follows.
(Conditions for solution treatment)
The heating temperature is a temperature selected from the range of 530°C or higher and 580°C or lower. The heating time is selected from the range of 15 minutes or more and 120 minutes or less.
(Conditions for aging treatment)
The heating temperature is a temperature selected from the range of 150°C or higher and 180°C or lower. The heating time is selected from the range of 4 hours or more and 100 hours or less.

The aluminum alloy of the present disclosure has the above-described specific composition, so that its strength is increased by precipitation hardening in the state of being subjected to solution treatment and aging treatment. From this point, the aluminum alloy of the present disclosure is less prone to creep deformation in the state of being subjected to solution treatment and aging treatment. In addition, the aluminum alloy of the present disclosure has a specific structure including subgrain boundaries in the above range in cross section. Subgrain boundaries are thought to provide resistance to dislocation motion in aluminum alloys. Creep deformation caused by diffusion of atoms and movement of dislocations is suppressed in aluminum alloys as the proportion of subgrain boundaries increases. From this point, the aluminum alloy of the present disclosure is less prone to creep deformation in the state of being subjected to solution treatment and aging treatment. As described above, the aluminum alloy of the present disclosure has excellent creep properties in the state of solution heat treatment and aging treatment.

In addition, the aluminum alloy of the present disclosure has well-balanced heat resistance, corrosion resistance, and strength in the state of solution heat treatment and aging treatment, similar to alloys called 6000 series alloys in the international alloy symbol. Such an aluminum alloy of the present disclosure can be suitably used as an aluminum alloy member that is required to have excellent creep properties in addition to heat resistance, corrosion resistance, and strength, and as a raw material for this aluminum alloy member. Examples of aluminum alloy members include automobile parts and various structural members. Automobile parts and various structural members can take the form of wires, bars, pipes, and the like. The raw material is, for example, an aluminum alloy wire, an aluminum alloy plate, or the like.

(2) The aluminum alloy of the present disclosure may further contain one or more elements selected from the group consisting of iron, chromium, zinc, titanium, and zirconium. The iron content is more than 0% by mass and 0.8% by mass or less. The content of chromium is more than 0% by mass and 0.35% by mass or less. The zinc content is more than 0% by mass and 0.5% by mass or less. The content of titanium is more than 0% by mass and 0.2% by mass or less. The content of zirconium is more than 0% by mass and 0.2% by mass or less.

In the above aluminum alloy, the existence ratio of subgrain boundaries tends to increase.

(3) The aluminum alloy of (2) above contains 0.9 mass % or more and 1.3 mass % or less of silicon, 0.8 mass % or more and 1.2 mass % or less of magnesium, and more than 0 mass % of iron. 4% by mass or less, 0.65% by mass or more and 1.1% by mass or less of copper, 0.55% by mass or more and 1.15% by mass or less of manganese, more than 0% by mass of chromium and 0.35% by mass or less, zinc 0.12% by mass or more and 0.25% by mass or less, more than 0% by mass and 0.075% by mass or less of titanium, 0.05% by mass or more and 0.17% by mass or less of zirconium, and the balance being aluminum and inevitable impurities composition.

In the above aluminum alloy, the existence ratio of subgrain boundaries tends to increase.

(4) The aluminum alloy of (2) above contains 0.6% by mass or more and 1.5% by mass or less of silicon, 0.7% by mass or more and 1.3% by mass or less of magnesium, and 0.02% by mass or more of iron. 0.4% by mass or less, 0.5% by mass or more and 1.2% by mass or less of copper, 0.5% by mass or more and 1.1% by mass or less of manganese, 0% by mass or more and 0.3% by mass or less of chromium, 0.005 mass% or more and 0.5 mass% or less of zinc, 0.01 mass% or more and 0.2 mass% or less of titanium, 0.05 mass% or more and 0.2 mass% or less of zirconium, and the balance being aluminum and It may have a composition consisting of unavoidable impurities.

In the above aluminum alloy, the existence ratio of subgrain boundaries tends to increase.

(5) In the aluminum alloy of the present disclosure, the product of the average value of the steady creep rate and the cube of the average grain size of the cross section in the state of solution treatment and aging treatment is 80 μm ³ / h or less. Hereinafter, the value obtained by multiplying the average value of the steady creep rate by the cube of the average grain size of the cross section is sometimes referred to as the creep evaluation value. The method for measuring the average value of the steady creep rate and the average grain size will be described later.

The above aluminum alloys are superior in creep properties.

(6) The aluminum alloy of the present disclosure may have an average crystal grain size of 10 μm or more and 200 μm or less in the cross section after solution treatment and aging treatment.

The above aluminum alloy has excellent creep properties and strength.

(7) An aluminum alloy wire according to an aspect of the present disclosure is made of the aluminum alloy according to any one of (1) to (6) above.

Since the aluminum alloy wire of the present disclosure is made of the aluminum alloy of the present disclosure, it has excellent creep properties in a state in which solution treatment and aging treatment have been performed. Such an aluminum alloy wire of the present disclosure can be used as a raw material for aluminum alloy members. The aluminum alloy wire of the present disclosure is excellent in manufacturability because it can be mass-produced by using, for example, the method for producing an aluminum alloy wire described later.

(8) A method for manufacturing an aluminum alloy wire according to one aspect of the present disclosure includes silicon of 0.6% by mass or more and 1.5% by mass or less, magnesium of 0.5% by mass or more and 1.3% by mass or less, and copper. Hot plastic working of an aluminum alloy cast material having a composition of more than 0.3% by mass and 1.2% by mass or less, containing 0.2% by mass or more and 1.15% by mass or less of manganese, and the balance being aluminum and inevitable impurities a step of producing a hot-worked material by applying a first softening treatment to the hot-worked material to produce a first softened material; and a first cold stretching of the first softened material. a step of producing a first drawn wire material by wire working; a step of producing a second softened material by subjecting the first drawn wire material to a second softening treatment; and a step of manufacturing a second drawn wire material by performing a second wire drawing process. The heating temperature of the first softening treatment and the second softening treatment is 300°C or higher and lower than 500°C. The working ratio of the first wire drawing is 30% or more. The working ratio of the second wire drawing is 20% or more.

The method for producing an aluminum alloy wire of the present disclosure can produce an aluminum alloy wire that has excellent creep properties in a state in which solution treatment and aging treatment have been performed. The reason for this will be described later.

(9) In the aluminum alloy wire manufacturing method of the present disclosure, the aluminum alloy may further contain one or more elements selected from the group consisting of iron, chromium, zinc, titanium, and zirconium. The iron content is more than 0% by mass and 0.8% by mass or less. The content of chromium is more than 0% by mass and 0.35% by mass or less. The zinc content is more than 0% by mass and 0.5% by mass or less. The content of titanium is more than 0% by mass and 0.2% by mass or less. The content of zirconium is more than 0% by mass and 0.2% by mass or less.

The above method for producing an aluminum alloy wire can produce an aluminum alloy wire with better creep properties.

[Details of the embodiment of the present disclosure]
Hereinafter, embodiments of the present disclosure will be specifically described with reference to the drawings as appropriate.

[Aluminum alloy]
(Overview)
The aluminum alloy of the embodiment has the following composition and cross-sectional structure. The composition of the aluminum alloy of the embodiment contains silicon, magnesium, copper, and manganese within the ranges described later, with the balance being aluminum and unavoidable impurities. The aluminum alloy of the embodiment may further contain one or more elements selected from the group consisting of iron, chromium, zinc, titanium, and zirconium within the range described below. The cross-sectional structure of the aluminum alloy of the embodiment includes subgrain boundaries 61 to some extent in the state where the solution treatment and aging treatment are performed as shown in the upper diagram of FIG. 3 . The composition and structure will be described in order below.

In the following description, the following notation may be used.
Silicon, magnesium, copper, and manganese are collectively referred to as primary elements. Iron, chromium, zinc, titanium, and zirconium are collectively referred to as secondary elements.
Each element is indicated by an element symbol. Si means silicon. Mg means magnesium. Cu means copper. Mn means manganese. Al means aluminum. Fe means iron. Cr means chromium. Zn means zinc. Ti means titanium. Zr means zirconium.
A state in which the aluminum alloy is subjected to solution treatment and aging treatment is referred to as a state after heat treatment.

(composition)
In the aluminum alloy of the embodiment, the first element is an essential element and the second element is an optional element. Quantitatively, the aluminum alloy of the embodiment contains 0.6% by mass or more and 1.5% by mass or less of silicon, 0.5% by mass or more and 1.3% by mass or less of magnesium, and more than 0.3% by mass of copper. 2% by mass or less, 0.2% to 1.15% by mass of manganese, 0% to 0.8% by mass of iron, 0% to 0.35% by mass of chromium, 0% by mass of zinc % or more and 0.5 mass % or less, 0 mass % or more and 0.2 mass % or less of titanium, 0 mass % or more and 0.2 mass % or less of zirconium, and the balance being aluminum and unavoidable impurities. The content of iron in the aluminum alloy of the embodiment containing one or more secondary elements is more than 0% by mass and 0.8% by mass or less. The content of chromium is more than 0% by mass and 0.35% by mass or less. The zinc content is more than 0% by mass and 0.5% by mass or less. The content of titanium is more than 0% by mass and 0.2% by mass or less. The content of zirconium is more than 0% by mass and 0.2% by mass or less.

Because the content of the first element is equal to or higher than the above-mentioned lower limit, compounds containing the first element are precipitated in the state after heat treatment. Since precipitates such as the above compounds are present in a dispersed state, an effect of improving strength by precipitation hardening can be obtained. When part of the first element is dissolved in aluminum, which is the main constituent of the matrix phase, the effect of improving strength by solid solution strengthening is also obtained. When the content of the first element is equal to or less than the above-described upper limit, grain boundary embrittlement due to segregation of the first element is suppressed, and compounds containing the first element are less likely to coarsen. Particles such as coarse compounds can be starting points of cracks. If the number of coarse particles is small, cracks due to the coarse particles are less likely to occur. From these points, the aluminum alloy of the embodiment is excellent in strength after heat treatment. The excellent strength makes it difficult for the aluminum alloy of the embodiment to undergo creep deformation. In the manufacturing process, cracks due to the coarse particles are less likely to occur, so cold plastic working such as cold wire drawing can be performed satisfactorily. From this point, the aluminum alloy of the embodiment is also excellent in manufacturability.

When the second element is contained in addition to the first element, one or more effects selected from the group consisting of precipitation hardening, solid solution strengthening, suppression of grain boundary embrittlement, and suppression of grain coarsening are exhibited. I can expect it. Due to such an effect, the aluminum alloy of the embodiment containing the second element in addition to the first element is less prone to creep deformation after heat treatment. When the content ratio of the second element satisfies the upper limit range described above, the compound or the like containing the second element is less likely to become coarse. In addition, depending on the type of the second element, the cast material can have a fine structure. From these points, the aluminum alloy of the embodiment containing the second element in addition to the first element is excellent in workability when plastic working is included in the manufacturing process. The casting temperature can be lowered depending on the type of the second element. From these points, the aluminum alloy of the embodiment containing the second element in addition to the first element is superior in manufacturability.

Specific examples of the composition containing the second element in addition to the first element include the following composition α and composition β.
<Composition α>
The composition α is 0.9% by mass to 1.3% by mass of silicon, 0.8% by mass to 1.2% by mass of magnesium, more than 0% by mass and 0.4% by mass or less of iron, and 0% by mass of copper. 0.65 mass % or more and 1.1 mass % or less, manganese of 0.55 mass % or more and 1.15 mass % or less, chromium of 0 mass % or more and 0.35 mass % or less, zinc of 0.12 mass % or more and 0.12 mass % or less. It contains 25 mass % or less, more than 0 mass % and 0.075 mass % or less of titanium, 0.05 mass % or more and 0.17 mass % or less of zirconium, and the balance consists of aluminum and unavoidable impurities. The composition α roughly corresponds to the composition of the alloy indicated by the international alloy symbol A6056.

<Composition β>
Composition β contains 0.6% by mass to 1.5% by mass of silicon, 0.7% by mass to 1.3% by mass of magnesium, 0.02% by mass to 0.4% by mass of iron, and copper 0.5% by mass to 1.2% by mass, manganese 0.5% by mass to 1.1% by mass, chromium more than 0% by mass and 0.3% by mass or less, zinc 0.005% by mass or more It contains 0.5 mass % or less, 0.01 mass % or more and 0.2 mass % or less of titanium, 0.05 mass % or more and 0.2 mass % or less of zirconium, and the balance consists of aluminum and unavoidable impurities. Composition β may further contain 0.005 mass % or more and 0.05 mass % or less of strontium.

The content range of the first element and the content range of the second element are exemplified below in the composition α and the composition β.
<Composition α>
The silicon content may be 0.9% by mass or more and 1.2% by mass or less.
The content of magnesium may be 0.8% by mass or more and 1.0% by mass or less.
The content of iron may be 0.10% by mass or more and 0.25% by mass or less.
The content of copper may be 0.65% by mass or more and 0.85% by mass or less.
The content of manganese may be 0.55% by mass or more and 0.80% by mass or less, or 0.55% by mass or more and 0.65% by mass or less.
The content of chromium may be 0.01% by mass or more and 0.10% by mass or less, or 0.02% by mass or more and 0.05% by mass or less.
The content of zinc may be 0.13% by mass or more and 0.25% by mass or less.
The content of titanium may be 0.001% by mass or more and 0.075% by mass or less, or 0.01% by mass or more and 0.075% by mass or less.
The content of zirconium may be 0.10% by mass or more and 0.17% by mass or less.
The total content of titanium and zirconium may be 0.11% by mass or more and 0.20% by mass or less.

<Composition β>
The content of silicon may be 0.8% by mass or more and 1.4% by mass or less, or 1.1% by mass or more and 1.3% by mass or less.
The content of magnesium may be 0.8% by mass or more and 1.3% by mass or less, or 0.8% by mass or more and 1.0% by mass or less.
The iron content may be 0.05% by mass or more and 0.40% by mass or less.
The content of copper may be 0.8% by mass or more and 1.2% by mass or less.
The manganese content may be 0.7% by mass or more and 1.1% by mass or less.
The content of chromium may be 0.01% by mass or more and 0.30% by mass or less, or 0.05% by mass or more and 0.30% by mass or less.
The content of zinc may be 0.05% by mass or more and 0.25% by mass or less.
The content of titanium may be 0.01% by mass or more and 0.15% by mass or less.
The content of zirconium may be 0.08% by mass or more and 0.2% by mass or less.
The total content of titanium and zirconium may be 0.10% by mass or more and 0.20% by mass or less.
When strontium is included, the content of strontium may be 0.005% by mass or more and 0.04% by mass or less.

<Other elements>
When titanium is included, the aluminum alloy of the embodiment may further include boron in the range of 50 ppm by mass or less.

(organization)
The present inventors have found that an aluminum alloy having excellent creep properties after heat treatment preferably has a structure containing subgrain boundaries to some extent. In other words, it is preferable not to have a structure substantially composed of recrystallized grains, but to have a structure containing a certain amount of subgrains that are not recrystallized grains. Quantitatively, in the aluminum alloy of the embodiment, the existence ratio of subgrain boundaries obtained by crystallographic analysis of the cross section by the SEM-EBSD method in the state after heat treatment is 15% or more. A known device and known image analysis software can be used for crystal analysis by the SEM-EBSD method.

If the existence ratio of subgrain boundaries is 15% or more, the aluminum alloy of the embodiment contains grain boundaries that act as resistance to dislocation movement to some extent. Subgrain boundaries suppress creep deformation caused by atomic diffusion and dislocation movement in aluminum alloys in the post-heat treatment state. The aluminum alloy of such an embodiment is less prone to creep deformation in the state after heat treatment. Creep deformation is suppressed as the existence ratio of subgrain boundaries increases. That is, creep characteristics are improved. From the viewpoint of improving creep properties, the proportion of subgrain boundaries may be 17% or more, 20% or more, or even 30% or more. The upper limit of the existence ratio of subgrain boundaries is 99%. That is, the existence ratio of subgrain boundaries is 15% or more and 99% or less. Considering manufacturability, the existence ratio of subgrain boundaries may be 90% or less, or 80% or less.

When the aluminum alloy of the embodiment constitutes a wire, the cross section for evaluating the existence ratio of subgrain boundaries is not the cross section cut along the plane perpendicular to the longitudinal direction of the wire, but the plane along the longitudinal direction. Use the cut cross section. Hereinafter, a cross section cut along a plane along the longitudinal direction of the wire made of the aluminum alloy of the embodiment, that is, the aluminum alloy wire 1 of the embodiment may be referred to as a longitudinal section. In the longitudinal section of the aluminum alloy wire 1 of the embodiment, the existence ratio of subgrain boundaries is evaluated. If the aluminum alloy wire 1 of such an embodiment has a length equal to or greater than the following predetermined length, the subgrain boundaries surely exist. The predetermined length is the length of the observation field of view of the longitudinal section used for evaluating the existence ratio of the subgrain boundaries. The predetermined length is, for example, 2 mm or more. The length of the observation field is the length along the longitudinal direction of the aluminum alloy wire 1 . If the aluminum alloy wire 1 having a length equal to or longer than the predetermined length is used as a raw material for an aluminum alloy member, an aluminum alloy member having excellent creep properties can be obtained.

In addition, in the aluminum alloy of the embodiment, only the solution treatment is performed, and the existence ratio of the subgrain boundaries is 15% or more even in a state in which the aging treatment is not performed. That is, it is considered that the existence ratio of subgrain boundaries does not substantially change before and after the aging treatment.

(creep evaluation value)
In the aluminum alloy of the embodiment, for example, after heat treatment, the product of the average steady creep rate and the cube of the average grain size of the cross section is 80 μm ³ /h or less. The present inventors adopted the steady creep rate of grain boundary diffusion creep as an index for evaluating the creep properties of aluminum alloys. In grain boundary diffusion creep, grain deformation occurs due to the diffusion of atoms along grain boundaries. The steady creep rate (%/h) in the grain boundary diffusion creep is obtained by the constitutive equation shown below (Equation 1).

In (Equation 1), dot ε is the steady creep rate. A is a material constant. D is the diffusion coefficient. G is the stiffness modulus. b is the magnitude of the Burgers vector. k is the Boltzmann constant. T is temperature. d is the grain size. σ is the applied stress.

In general, the smaller the steady creep rate of a metal, the less likely it is to undergo creep deformation. According to the above (Formula 1), the larger the grain size d, the smaller the steady creep rate. By multiplying both sides of the above (Equation 1) by the cube of the crystal grain size d, the effect of the crystal grain size d is also reflected on the left side of the above (Equation 1). That is, the creep evaluation value obtained by the product of the steady creep rate (%/h) and the cube of the grain size d reflects the effect of the grain size d described above. It is considered that such a creep evaluation value can appropriately evaluate factors other than grain size d, such as atomic diffusion and dislocation movement, as factors of creep deformation.

The aluminum alloy of the embodiment having a creep evaluation value of 80 μm ³ /h or less is less prone to creep deformation after heat treatment. The smaller the creep evaluation value, the more difficult it is for the aluminum alloy to undergo creep deformation. From the viewpoint of improving the creep property, the creep evaluation value may be 70 μm ³ /h or less, 60 μm ³ /h or less, or even 50 μm ³ /h or less.

There is no particular lower limit for the creep evaluation value. The creep evaluation value is, for example, 0.1 μm ³ /h or more. An aluminum alloy having a creep evaluation value of 0.1 μm ³ /h or more and 80 μm ³ /h or less does not require excessive plastic working in the manufacturing process and is easy to manufacture.

(Average grain size)
For example, the aluminum alloy of the embodiment has an average grain size of 10 μm or more and 200 μm or less in a cross section after heat treatment. If the average crystal grain size is 10 μm or more, the steady creep rate represented by the above-mentioned (Equation 1) tends to become small. If the average crystal grain size is 200 μm or less, the crystal grains are small to some extent, and the strength tends to be high. Therefore, the aluminum alloy of the embodiment in which the average crystal grain size is within the above range has excellent creep properties and excellent strength. From the viewpoint of providing good creep property and high strength in a well-balanced manner, the average crystal grain size may be 15 μm or more and 190 μm or less, or 20 μm or more and 180 μm or less.

The above average grain size is a value obtained by averaging the grain size of each grain obtained by crystallographic analysis of the cross section of the aluminum alloy of the embodiment by the SEM-EBSD method. The grain size of each grain is the diameter of a circle having an area equal to the cross-sectional area of each grain in the cross section.

(Usage form)
The aluminum alloys of embodiments can have various shapes. For example, the aluminum alloys of the embodiments have somewhat long shapes. The aluminum alloy of such an embodiment has an end surface which is a plane perpendicular to its longitudinal direction and an extension extending in the longitudinal direction. The length of the extension along the longitudinal direction is greater than the diameter of a circle having an area equal to the area of the outer contour of the end face. In the aluminum alloy of the embodiment having the stretched portion, the cross section to be measured for the existence ratio of subgrain boundaries is obtained by cutting the stretched portion along the plane along the longitudinal direction.

　The aluminum alloy of the embodiment having an extended portion is, for example, a wire rod, a pipe, a plate material, or the like. That is, the extending portion may be a solid body such as a wire rod or a plate material, or a hollow body such as a pipe.

<wire>
An aluminum alloy wire 1 of the embodiment is made of the aluminum alloy of the embodiment. The aluminum alloy wire 1 of the embodiment has an end surface 10 and an extension portion 11 as shown in FIG. The end surface 10 here is a surface perpendicular to the longitudinal direction of the aluminum alloy wire 1 . The extending portion 11 extends in the longitudinal direction. The aluminum alloy wire 1 of the embodiment typically has the same outer contour and the same wire diameter over the entire length of the extended portion 11 as shown in FIG. The wire diameter here is the diameter of a circle having the same area as the area of the end face 10 or the area of a cross section cut along a plane perpendicular to the longitudinal direction. FIG. 1 exemplifies the case where the outer peripheral contour of the end face 10 and the outer peripheral contour of an arbitrary cross section cut along a plane perpendicular to the longitudinal direction are circular. The outer contour of the end face 10 and the outer contour of the cross section may be polygonal such as square, or may be curved such as elliptical. The wire diameter of the aluminum alloy wire 1 of the embodiment is not particularly limited. The wire diameter is, for example, about 3 mm or more and 15 mm or less.

In the aluminum alloy wire 1 of the embodiment, as described above, the cross section to be measured for the existence ratio of subgrain boundaries is the vertical cross section. In the aluminum alloy wire 1 of the embodiment, the proportion of existence of subgrain boundaries in the longitudinal section is 15% or more. Further, in the aluminum alloy wire 1 of the embodiment, the creep evaluation value obtained by multiplying the average value of the steady creep rate by the cube of the average grain size of the longitudinal section is, for example, 80 μm ³ /h or less. The average grain size of the longitudinal section is, for example, 10 μm or more and 200 μm or less.

<Aluminum alloy member>
The aluminum alloy of the embodiment can constitute an aluminum alloy member. For example, the aluminum alloy member is made of the aluminum alloy of the embodiment and subjected to solution treatment and aging treatment. A specific example is an aluminum alloy member obtained by subjecting the aluminum alloy wire 1 of the embodiment to plastic working, followed by solution treatment and aging treatment. Another example is an aluminum alloy member obtained by subjecting a plate material made of the aluminum alloy of the embodiment to plastic working, followed by solution treatment and aging treatment. Plastic processing here includes, for example, extrusion processing, forging processing, wire drawing processing, and the like. Still another example is an aluminum alloy member obtained by subjecting the aluminum alloy wire 1 of the embodiment to solution treatment and aging treatment. That is, the aluminum alloy member may be linear or bar-shaped. Alternatively, the aluminum alloy member may be tubular. The aluminum alloy wire 1 of the embodiment can thus be used as a raw material for aluminum alloy members.

The aluminum alloy member described above is excellent in creep properties because it is made of an aluminum alloy having the above-described specific composition and the above-described specific structure. Moreover, this aluminum alloy member is lighter than a metal member made of an iron-based alloy such as steel. Such aluminum alloy members can be used in applications where light weight and excellent creep properties are desired, such as automobile parts and various structural members.

(Method for producing aluminum alloy)
The present inventors have investigated a method for producing an aluminum alloy having the specific composition described above and exhibiting excellent creep properties in the state of solution heat treatment and aging treatment. As a result, the inventors have found that it is preferable to satisfy the following conditions. Based on this finding, the method of manufacturing the aluminum alloy of the embodiment includes, for example, the following first step, second step, third step, fourth step, and fifth step.
<conditions>
Cold plastic working. The material to be subjected to this plastic working is subjected to a softening treatment, and the softening treatment is also performed during the plastic working. These softening treatments are performed at relatively low temperatures. The plastic working before and after the softening treatment is performed with a large degree of working.

The first step is a step of producing a hot-worked material by subjecting a cast material of an aluminum alloy containing the above-mentioned first element within the above-described range and the balance being aluminum and unavoidable impurities to hot plastic working. In addition to the first element, the aluminum alloy forming the cast material may further contain the second element within the range described above.
The second step is a step of producing a first softened material by subjecting the hot-worked material to a first softening treatment.
The third step is a step of producing a first plastically worked material by subjecting the first softened material to cold first plastic working.
The fourth step is a step of manufacturing a second softened material by subjecting the first plastically worked material to a second softening treatment.
The fifth step is a step of producing a second plastically worked material by subjecting the second softened material to cold second plastic working.
The heating temperature of the first softening treatment and the second softening treatment is 300°C or higher and lower than 500°C.
The workability of the first plastic working is 30% or more.
The workability of the second plastic working is 20% or more.

The aluminum alloy produced by the above-described production method has a structure that includes subgrain boundaries to some extent in the state of being subjected to solution treatment and aging treatment. The reason why such an organization is provided is considered as follows. Hereinafter, with reference to FIGS. 2 and 3, the process of forming a structure including subgrain boundaries when solution treatment and aging treatment are performed after the above-described second plastic working will be described. 2 and 3 show the progress of recrystallization from the top of FIG. 2 to the bottom of FIG. Dashed lines and thick solid lines in FIGS. 2 and 3 indicate large- angle boundaries 51 and 52 . A thin solid line indicates a subgrain boundary 61 .

As shown in the upper diagram of FIG. 2, dislocation cells are rearranged by performing solution treatment after the second plastic working. When a dislocation cell becomes a subgrain, a subgrain boundary 61 is formed if the orientation difference between adjacent cells is small. When the orientation difference between adjacent cells is large, large-angle boundaries 51 are formed in some subgrains. Large-angle boundaries 51 mainly move in the subsequent growth of subgrains. Subgrains can grow due to the movement of the large-angle boundary 51 . Further, when a subgrain meets another subgrain having a similar orientation as the subgrain grows, a subgrain boundary 61 is formed between the two subgrains. As a result, the movement of subgrains stops.

As shown in the middle diagram of FIG. 2, when several subgrains 60 surrounded by subgrain boundaries 61 are gathered, a structure is formed in which the large-angle boundary 52 surrounds the entire periphery of these grains. The tissue is called "recovery tissue". 2 and 3 show the large-angle boundary 52 with a thick solid line for easy understanding.

As shown in the lower diagram of FIG. 2, the large-angle boundary 52 moves in the state where the large-angle boundary 52 is formed between the recovery tissues. Movement of the large-angle boundary 52 causes some restorative tissue to erode other restorative tissue as shown in the upper diagram of FIG. As a result, the subgrains 60 grow while being held inside the structure surrounded by the large-angle boundaries 52 . That is, a structure containing many subgrains 60 and subgrain boundaries 61 is formed.

On the other hand, as the recovery phenomenon progresses, almost no subgrains 60 and subgrain boundaries 61 remain, and a structure composed of recrystallized grains 50 is formed as shown in the lower part of FIG. In addition, it is considered that such a structure is mainly formed during the solution treatment. Even if the aging treatment is performed after the solution treatment, it is considered that the structure after the solution treatment but before the aging treatment is substantially maintained.

In general, softening treatment releases at least part of the strain, ie, dislocations introduced into the aluminum alloy by plastic working before softening treatment. In the manufacturing method described above, although the first softening treatment and the second softening treatment are performed, the heating temperature is relatively low as described above. Therefore, it is considered that the solid solution of the element having a smaller diffusion coefficient than that of Al is maintained even when the softening treatment is performed. As a result, it is considered that the recovery of dislocations is hindered during the solution treatment, that is, the recovery phenomenon hardly progresses.

In addition, the plastic workability of the softened material is enhanced by performing the first softening treatment and the second softening treatment. Therefore, the working ratio of the first plastic working and the working ratio of the second plastic working can be increased. Dislocations can be accumulated in the aluminum alloy by the plastic working because the working degree of the plastic working is large. In particular, cold plastic working tends to accumulate dislocations in an aluminum alloy as compared with warm working or hot working. That is, in the above-described manufacturing method, an aluminum alloy in which dislocations are accumulated after the second plastic working is obtained. Dislocations are released more easily in hot working and warm working than in cold working. It is considered that aluminum alloys in which dislocations have accumulated are less susceptible to the above-described recovery phenomenon even if they are subjected to solution treatment and aging treatment. Since the recovery phenomenon is difficult to progress in this manner, a structure containing subgrain boundaries to some extent is likely to be obtained.

A method for producing the aluminum alloy described above will be specifically described below.
<First step>
In the first step, the cast material is manufactured using, for example, a die casting method, a continuous casting method, or the like. In the first step, the hot plastic working is, for example, hot rolling, and the hot worked material is, for example, continuously cast and rolled material. If the hot-worked material is a continuously cast and rolled material, for example, a continuous long aluminum alloy wire can be produced. In this respect, the aluminum alloy wire 1 of the embodiment can be mass-produced in a form in which the hot-worked material is a continuously cast and rolled material.

<Second process>
The conditions for the first softening treatment in the second step and the conditions for the second softening treatment in the fourth step, which will be described later, are as follows.
《Conditions for softening treatment》
The heating temperature is a temperature selected from the range of 300°C or higher and lower than 500°C. The retention time is a time selected from the range of 1 hour or more and 100 hours or less. The softening atmosphere is, for example, an air atmosphere or a non-oxidizing atmosphere. The non-oxidizing atmosphere is, for example, a reduced pressure atmosphere, an inert gas atmosphere, a reducing gas atmosphere, or the like.

By setting the heating temperature of the softening treatment to 300°C or higher, the degree of processing of the first plastic working and the degree of working of the second plastic working can be increased. When the heating temperature of the softening treatment is less than 500° C., the recovery phenomenon hardly progresses during the solution treatment as described above. The heating temperature may be 350° C. or higher and 480° C. or lower, further 350° C. or higher and 460° C. or lower, from the viewpoint of increasing the workability and suppressing the progress of the recovery phenomenon.

<Third process>
In the third step, the first plastic working is, for example, wire drawing, rolling, or forging. When the degree of working of the first plastic working in the third step is 30% or more, even if some of the dislocations introduced by the first plastic working are released by the second softening treatment, the dislocations tend to remain to some extent. . As a result, it is easy to finally obtain an aluminum alloy in which many dislocations are accumulated. The workability of the first plastic working may be 35% or more and 40% or more. The working ratio of the first plastic working depends on the final size such as the final wire diameter, but is selected from a range of, for example, 30% or more and 80% or less. The working degree of the first plastic working is a ratio obtained by dividing the difference between the cross-sectional area before the first plastic working and the cross-sectional area after the first plastic working by the cross-sectional area before the first plastic working. The working degree of the first plastic working in the third step is larger than the working degree of the second plastic working in the fifth step described later, for example.

<Fourth step>
The conditions and effects of the second softening treatment in the fourth step are as described above.

<Fifth step>
In the fifth step, the second plastic working is, for example, wire drawing, rolling, or forging. The kind of the second plastic working may be the same as or different from the kind of the first plastic working in the third step. If the workability of the second plastic working in the fifth step is 20% or more, it is easy to finally obtain an aluminum alloy in which many dislocations are accumulated. The working ratio of the second plastic working may be 23% or more, and may be 25% or more. The working ratio of the second plastic working is selected from a range of, for example, 20% or more and less than 80% so that a second plastic working material having a predetermined final size such as a final wire diameter can be obtained. The working degree of the second plastic working is a ratio obtained by dividing the difference between the cross-sectional area before the second plastic working and the cross-sectional area after the second plastic working by the cross-sectional area before the second plastic working.

(Manufacturing method of aluminum alloy wire)
In order to manufacture the aluminum alloy wire 1 of the embodiment, the method of manufacturing the aluminum alloy wire of the embodiment can be used. In the method for manufacturing an aluminum alloy wire of the embodiment, the following replacements are made in the method for manufacturing an aluminum alloy described above. The first plastic working is read as the first wire drawing. The first plastically worked material is read as the first drawn wire material. The second plastic working is read as the second wire drawing. The second plastically worked material is read as the second drawn wire material. As described above, a material made of an aluminum alloy having a specific composition is excellent in cold wire drawability. The aluminum alloy wire manufacturing method of the embodiment using such a material can mass-produce the aluminum alloy wire 1 of the embodiment. For basic operations in the method for manufacturing an aluminum alloy wire of the embodiment, reference can be made to a known method for manufacturing an aluminum alloy wire.

(Manufacturing method of aluminum alloy member)
A method for manufacturing the aluminum alloy member described above includes, for example, the following processing steps and heat treatment steps.
The working step is a step of manufacturing a third worked material by applying a third plastic working to the second plastic worked material subjected to the second plastic working or the second drawn wire material to which the second wire drawing has been performed. is.
The heat treatment step is a step of sequentially subjecting the third processed material to solution treatment and aging treatment to produce an aged material.
The third plastic processing includes, for example, extrusion processing, forging processing, wire drawing processing, and the like. The conditions for solution treatment and aging treatment are as described above.

[Main effects of the embodiment]
The aluminum alloy according to the embodiment and the aluminum alloy wire 1 according to the embodiment are excellent in creep properties in a state of being subjected to solution treatment and aging treatment. In Test Example 1 below, the above effect will be specifically described by taking the aluminum alloy wire 1 of the embodiment as an example.

The method for manufacturing an aluminum alloy wire according to the embodiment can manufacture the aluminum alloy wire 1 according to the embodiment which has excellent creep properties in a state in which solution treatment and aging treatment have been performed.

[Test Example 1]
Microstructural observation and creep properties were investigated in the state where the aluminum alloy wires having the compositions shown in Table 1 were subjected to solution treatment and aging treatment. Tables 2 and 3 show the conditions for manufacturing the aluminum alloy wires and the results of the investigation.

(Preparation of sample)
The aluminum alloy wire of each sample is manufactured by subjecting a continuously cast and rolled material to the first softening treatment and then to cold drawing. A continuously cast rolled material can be produced by, for example, a known Propertit type continuous casting and rolling mill. A second softening treatment is performed during the wire drawing process. The wire drawing process before the second softening treatment is called the first wire drawing process. The wire drawing after the second softening treatment is called second wire drawing. The aluminum alloy wire of each sample is manufactured by subjecting a continuously cast rolled material to first softening treatment, first wire drawing, second softening treatment and second wire drawing in this order.
In Tables 2 and 3, composition α and composition β in the item of composition correspond to composition α and composition β shown in Table 1, respectively.
In Tables 2 and 3, the item of softening treatment indicates heating temperature (° C.) and holding time (hour). For example, "380° C.×10 h" means that the heating temperature is 380° C. and the holding time is 10 hours.
The first wire drawing and the second wire drawing are performed at the degree of working (%) shown in Tables 2 and 3, respectively.
The wire diameter of the continuously cast rolled material is selected from the range of 5 mm or more and 30 mm or less. The wire diameter of the second drawn wire manufactured after the second wire drawing is a value selected from the range of approximately 1.0 mm or more and 21 mm or less depending on the degree of working.

(Organization observation)
<Ratio of existence of subgrain boundaries>
The obtained aluminum alloy wire of each sample is subjected to solution treatment and aging treatment under the conditions described above to produce a heat treated wire. The obtained heat-treated wire is cut along a plane along the longitudinal direction of the heat-treated wire to obtain a longitudinal section. This longitudinal section is smoothed by mechanical polishing. Crystallographic analysis of the polished longitudinal section is performed by the SEM-EBSD method. The observation field of view has a size of 1 mm along the radial direction of the heat-treated wire and a size of 2.5 mm along the longitudinal direction of the heat-treated wire. An EBSD pattern is obtained by irradiating an electron beam at a pitch of 1.0 μm to the rectangular observation field. Image analysis of the EBSD pattern provides crystal orientation data. Based on the crystal orientation data, the crystal grains are identified and the misorientation of the crystal grain boundary is analyzed. Acquisition of crystal orientation data and image analysis can be automatically performed using a known device. Here, OIM6.2.0 by TSL Solutions Co., Ltd. is used as image analysis software. In addition, image analysis is performed using data points having a confidence value coefficient CI value of 0.1 or more in this image analysis software.

Using the results of the above image analysis, determine the length of the subgrain boundary and the length of the large angle boundary. Furthermore, the total length of the length of the subgrain boundary and the length of the large angle boundary is obtained. The ratio obtained by dividing the subgrain boundary length (μm) by the total length (μm) is obtained. Here, the above ratio is obtained in one observation field of view. The existence ratio (%) of subgrain boundaries shown in Tables 2 and 3 is the above ratio.

<Average grain size>
The grain size of each crystal grain is determined using the result of the image analysis described above. Here, the grain sizes of all crystal grains included in one observation field are obtained. The average crystal grain size (μm) shown in Tables 2 and 3 is a value obtained by averaging the grain sizes of all the above crystal grains.

(creep property)
A creep test is performed under the following conditions, and an average steady creep rate is obtained.
<Conditions of creep test>
The applied pressure is 250 MPa. The heating temperature is 150°C. The retention time is 150 hours.

<Average steady-state creep rate>
In the above creep test, the steady creep rate is determined every 5 hours over the holding time range of 35 hours to 135 hours. In other words, a total of 21 steady creep rates are obtained. Steady creep rate is determined according to JIS Z 2271:2010. The average value (%/h) of the steady creep rate shown in Tables 2 and 3 is the average value of the total 21 steady creep rates described above. Tables 2 and 3 index the average steady creep rate. For example, "1.09E-04" means "1.09×10 ^-4 ".

<Creep evaluation value>
The creep evaluation values shown in Tables 2 and 3 are the product of the average steady creep rate (%/h) and the cube of the average crystal grain size (μm).

<Component analysis>
The composition of the aluminum alloy wire of each sample obtained is the same as the composition in Table 1. That is, the aluminum alloy constituting the aluminum alloy wire of each sample contains the elements shown in Table 1 within the range shown in Table 1, and the balance is Al and unavoidable impurities. A known method can be used to analyze the composition of the aluminum alloy wire. For example, an energy dispersive X-ray spectrometer or the like can be used to analyze the composition.

In the explanation below, sample No. 1 to No. 4, No. 11 to No. 14 may be collectively referred to as the first sample group. Sample no. 101 to No. 104 may be collectively referred to as a second sample group.

As shown in Tables 2 and 3, the aluminum alloy wires of the first sample group have smaller creep evaluation values than the aluminum alloy wires of the second sample group. Quantitatively, the creep evaluation value of the aluminum alloy wire of the first sample group is 80 μm ³ /h or less, and further 50 μm ³ /h or less. Some samples have a creep evaluation value of 20 μm ³ /h or less. A small creep evaluation value indicates that the aluminum alloy wire of the first sample group is less prone to creep deformation than the aluminum alloy wire of the second sample group.

One of the reasons why the above results were obtained is thought to be the difference in the existence ratio of subgrain boundaries. The aluminum alloy wire of the first sample group, which has a small creep evaluation value, has a larger proportion of subgrain boundaries than the aluminum alloy wire of the second sample group. Quantitatively, the existence ratio of subgrain boundaries in the aluminum alloy wire of the first sample group is 15% or more, and further 17% or more. Many samples have a subgrain boundary existence ratio of 20% or more. It is believed that the presence of a large subgrain boundary suppresses the creep deformation caused by the diffusion of atoms and movement of dislocations in the aluminum alloy.

It should be noted that, when compared with the same composition, the average crystal grain size of the aluminum alloy wire of the first sample group is smaller than the average crystal grain size of the aluminum alloy wire of the second sample group. In this respect, the average steady creep rate of the aluminum alloy wires of the first sample group tends to be higher than the average steady creep rate of the aluminum alloy wires of the second sample group. However, if the creep property is evaluated by the creep evaluation value that reflects the influence of the grain size, the aluminum alloy wire of the first sample group is superior in creep property to the aluminum alloy wire of the second sample group. shown.

In addition, this test shows the following.
(1) An aluminum alloy wire having a composition β tends to have a larger proportion of subgrain boundaries than an aluminum alloy wire having a composition α. From this point of view, the aluminum alloy wire having the composition β is superior in creep properties.
(2) The average grain size of the aluminum alloy wire of the first sample group is 10 μm or more and 200 μm or less. From this point of view, the aluminum alloy wires of the first sample group are excellent in creep property and also in strength.
(3) An aluminum alloy wire having a large proportion of subgrain boundaries in the state of being subjected to solution treatment and aging treatment can be produced by a production method that satisfies the above <conditions>. In the aluminum alloy wires of the second sample group, the temperature of the first softening treatment is higher than that of the aluminum alloy wires of the first sample group. Therefore, it is considered that the existence ratio of the subgrain boundaries decreased in the aluminum alloy wires of the second sample group.

The present disclosure is not limited to these examples, but is indicated by the scope of the claims, and is intended to include all modifications within the meaning and scope of equivalents of the scope of the claims. For example, in Test Example 1, it is possible to change the composition of the aluminum alloy, or to change the manufacturing conditions such as the workability of wire drawing and the conditions of softening treatment.

1 aluminum alloy wire, 10 end face, 11 extension part 50 recrystallized grain, 51, 52 large angle boundary 60 subgrain, 61 subgrain boundary

Claims (9)

1. 0.6% by mass or more and 1.5% by mass or less of silicon,
   0.5% by mass or more and 1.3% by mass or less of magnesium,
   More than 0.3% by mass of copper and 1.2% by mass or less,
   A composition containing 0.2% by mass or more and 1.15% by mass or less of manganese, with the balance being aluminum and inevitable impurities,
   The existence ratio of subgrain boundaries obtained by crystallographic analysis of the cross section by the SEM-EBSD method in the state where solution treatment and aging treatment are performed is 15% or more.
   aluminum alloy.
2. Furthermore, containing one or more elements selected from the group consisting of iron, chromium, zinc, titanium, and zirconium,
   The iron content is more than 0% by mass and 0.8% by mass or less,
   The content of chromium is more than 0% by mass and 0.35% by mass or less,
   The content of zinc is more than 0% by mass and 0.5% by mass or less,
   The content of titanium is more than 0% by mass and 0.2% by mass or less,
   2. The aluminum alloy according to claim 1, wherein the content of zirconium is more than 0% by mass and 0.2% by mass or less.
3. 0.9% by mass or more and 1.3% by mass or less of silicon,
   0.8% by mass or more and 1.2% by mass or less of magnesium,
   More than 0% by mass and 0.4% by mass or less of iron,
   0.65% by mass or more and 1.1% by mass or less of copper,
   0.55% by mass or more and 1.15% by mass or less of manganese,
   More than 0% by mass and 0.35% by mass or less of chromium,
   0.12% by mass or more and 0.25% by mass or less of zinc,
   More than 0% by mass and 0.075% by mass or less of titanium,
   3. The aluminum alloy according to claim 2, comprising 0.05% by mass or more and 0.17% by mass or less of zirconium, with the balance being aluminum and unavoidable impurities.
4. 0.6% by mass or more and 1.5% by mass or less of silicon,
   0.7% by mass or more and 1.3% by mass or less of magnesium,
   0.02% by mass or more and 0.4% by mass or less of iron,
   0.5% by mass or more and 1.2% by mass or less of copper,
   0.5% by mass or more and 1.1% by mass or less of manganese,
   More than 0% by mass and 0.3% by mass or less of chromium,
   0.005% by mass or more and 0.5% by mass or less of zinc,
   0.01% by mass or more and 0.2% by mass or less of titanium,
   3. The aluminum alloy according to claim 2, comprising 0.05% by mass or more and 0.2% by mass or less of zirconium, with the balance being aluminum and unavoidable impurities.
5. The product of the average value of the steady creep rate and the cube of the average grain size of the cross section in the state of solution treatment and aging treatment is 80 μm ³ /h or less. 5. The aluminum alloy according to any one of items 4.
6. The aluminum alloy according to any one of claims 1 to 5, wherein the average crystal grain size of the cross section is 10 µm or more and 200 µm or less in a state in which solution treatment and aging treatment have been performed.
7. Made of the aluminum alloy according to any one of claims 1 to 6,
   aluminum alloy wire.
8. 0.6 mass % to 1.5 mass % of silicon, 0.5 mass % to 1.3 mass % of magnesium, more than 0.3 mass % to 1.2 mass % of copper, and 0.2 mass % of manganese A step of producing a hot-worked material by subjecting a cast material of an aluminum alloy having a composition containing not less than 1.15% by mass and the balance consisting of aluminum and inevitable impurities to hot plastic working;
   a step of subjecting the hot-worked material to a first softening treatment to produce a first softened material;
   a step of subjecting the first softened material to cold first wire drawing to produce a first drawn wire;
   a step of subjecting the first wire drawn material to a second softening treatment to produce a second softened material;
   a step of manufacturing a second wire drawn material by subjecting the second softened material to cold second wire drawing,
   The heating temperature of the first softening treatment and the second softening treatment is 300° C. or more and less than 500° C.,
   The working degree of the first wire drawing is 30% or more,
   The working degree of the second wire drawing is 20% or more,
   A method for producing an aluminum alloy wire.
9. The aluminum alloy further contains one or more elements selected from the group consisting of iron, chromium, zinc, titanium, and zirconium,
   The iron content is more than 0% by mass and 0.8% by mass or less,
   The content of chromium is more than 0% by mass and 0.35% by mass or less,
   The content of zinc is more than 0% by mass and 0.5% by mass or less,
   The content of titanium is more than 0% by mass and 0.2% by mass or less,
   The method for producing an aluminum alloy wire according to claim 8, wherein the content of zirconium is more than 0% by mass and 0.2% by mass or less.

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