Aluminum alloy materials and cables, wires and spring components using them

Abstract

The aluminum alloy material of the present invention has high bending fatigue resistance and a specified elongation. It contains, by mass percent, Mg: 0.20-1.80%, Si: 0.20-2.00%, and Fe: 0.01-1.50%, and also contains one or more elements selected from Cu, Ag, Zn, Ni, Ti, Co, Au, Mn, Cr, V, Zr, and Sn: totaling 0.00-2.00%, with the balance being Al and unavoidable impurities. It has a fibrous metallic structure with grains extending in one direction. In a cross-section of the aluminum alloy material perpendicular to the long side direction of the aforementioned grains, the average grain size R1 of the grains present at a thickness position D that is 1 / 20 of the thickness of the aforementioned aluminum alloy material from the surface of the aforementioned aluminum alloy material is 400 nm or less, and the ratio (R2 / R1) of the average grain size R2 of the grains present at the center of the thickness of the aforementioned aluminum alloy material to the aforementioned average grain size R1 is 1.8 or more.

Description

Technical Field

[0001] This invention relates to aluminum alloy materials and cables, wires and spring components using the same. Background Technology

[0002] Copper-based metals have long been widely used in cables that transmit power or signals, such as thick rubber flexible cables for robots and elevator cables. Recently, research has been conducted on replacing them with aluminum-based materials. Compared with copper-based metals, aluminum-based materials have a lower specific gravity, a higher coefficient of thermal expansion, better electrical and thermal conductivity, and superior corrosion resistance.

[0003] However, pure aluminum materials have a lower number of bending fatigue fractures (hereinafter referred to as bending fatigue resistance) compared to copper-based metals. Furthermore, aluminum alloys of the 2000 series (Al-Cu series) and 7000 series (Al-Zn-Mg series), which utilize precipitation strengthening and have relatively high bending fatigue resistance, suffer from the following problems: poor corrosion resistance, stress corrosion cracking resistance, and low electrical conductivity; etc. While 6000 series aluminum alloys, which have excellent electrical and thermal conductivity and corrosion resistance, possess relatively high bending fatigue resistance among aluminum alloys, this is not sufficient, and further improvement in bending fatigue resistance is desired.

[0004] On the other hand, as a method to improve the bending fatigue resistance of conductive aluminum alloys, a fine grain formation method based on a strong processing method such as the ECAP method has been proposed (e.g., Patent Document 1). However, the aluminum alloy wires manufactured by the ECAP method are short in length, making industrial application difficult. Furthermore, the aluminum alloy wires produced using the ECAP method as described in Patent Document 1 have fewer than 10 times the number of repeated fractures (fracture repetitions) compared to pure aluminum wires, meaning they cannot be said to possess sufficient bending fatigue resistance to withstand long-term use. Additionally, the aluminum alloy wires produced using the strong processing method have poor elongation, resulting in frequent wire breakage during drawing and stranding processes.

[0005] Furthermore, Patent Document 2 describes a copper-coated aluminum alloy wire with increased strength by coating a core of an Al-Fe-Mg-Si aluminum alloy with copper and then cold-working it. However, in the copper-coated aluminum alloy wire described in Patent Document 2, the copper-based material, which is prone to plastic deformation due to its low elastic limit, exists in the wire surface layer where bending strain increases. Therefore, cracks are easily generated on the surface of the copper coating layer during repeated bending. In addition, the compound formed between the aluminum alloy core and the copper coating layer can become crack initiation points, etc., resulting in poor bending fatigue resistance.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2013 / 146762

[0009] Patent Document 2: Japanese Patent Application Publication No. 2010-280969 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] The purpose of this invention is to provide an aluminum alloy material that has high resistance to bending fatigue while having a specified elongation, and cables, wires and spring components using the same.

[0012] Methods for solving problems

[0013] The main structure of this invention is as follows.

[0014] [1] An aluminum alloy material, characterized in that it has the following alloy composition:

[0015] It contains, by mass percent, Mg: 0.20–1.80%, Si: 0.20–2.00%, and Fe: 0.01–1.50%, and also contains one or more elements selected from the group consisting of Cu, Ag, Zn, Ni, Ti, Co, Au, Mn, Cr, V, Zr, and Sn: totaling 0.00–2.00%, with the balance being Al and unavoidable impurities;

[0016] The aforementioned aluminum alloy material has a fibrous metallic structure in which grains extend in one direction. In a cross-section of the aluminum alloy material perpendicular to the long side direction in which the grains extend, the average grain size R1 of the grains present at a thickness position D, which is equivalent to 1 / 20 of the thickness of the aforementioned aluminum alloy material from the surface of the aforementioned aluminum alloy material, is 400 nm or less. Furthermore, the ratio (R2 / R1) of the average grain size R2 of the grains present at the thickness center position C of the aforementioned aluminum alloy material to the average grain size R1 at the aforementioned thickness position D is 1.8 or more.

[0017] [2] As described in [1] above, in the cross section of the aluminum alloy material parallel to the long side direction of the aforementioned grain extension, the ratio (L1 / L2) of the long side direction dimension L1 of the grain present at the aforementioned thickness position D along the aforementioned long side direction to the short side direction dimension L2 measured along the direction perpendicular to the aforementioned long side direction is 10 or more.

[0018] [3] The aluminum alloy material as described in [1] or [2] above, wherein the aforementioned aluminum alloy material is wire.

[0019] [4] The aluminum alloy material as described in [3] above, wherein the wire diameter of the aforementioned wire is 0.01 to 1.50 mm.

[0020] [5] The aluminum alloy material as described in [1] or [2] above, wherein the aforementioned aluminum alloy material is a sheet material.

[0021] [6] The aluminum alloy material as described in [5] above, wherein the thickness of the aforementioned plate is 0.02 to 2.00 mm.

[0022] [7] The cable is made of any one of the aluminum alloy materials described in [3] to [6] above.

[0023] [8] The wire is made of any one of the aluminum alloy materials described in [3] to [6] above.

[0024] [9] The spring component uses the aluminum alloy material described in any one of [3] to [6] above.

[0025] The effects of the invention

[0026] According to the present invention, it is possible to provide aluminum alloy materials that have high resistance to bending fatigue while having a specified elongation, as well as cables, wires and spring components using the same. Attached Figure Description

[0027] [ Figure 1 [A schematic cross-sectional view of the aluminum alloy material in the embodiment, perpendicular to the long side direction, (a) shows the case where the aluminum alloy material is wire, and (b) shows the case where the aluminum alloy material is sheet.]

[0028] [ Figure 2 [A schematic diagram showing the state of grains in the aluminum alloy material of the embodiment, (a) shows the state of grains present at the thickness position D, and (b) shows the state of grains present at the thickness center position C.]

[0029] [ Figure 3 This is a schematic diagram of an apparatus for measuring bending fatigue resistance.

[0030] [ Figure 4 [SIM image showing a cross-section of the aluminum alloy wire of Example 1 parallel to the long side direction.]

[0031] [ Figure 5 This is a SIM image showing a portion of the aluminum alloy wire of Example 1 at a thickness position corresponding to 1 / 20 of the wire diameter from the wire surface in a cross section perpendicular to the long side direction.

[0032] [ Figure 6 This image shows a SIM image of the center portion of the aluminum alloy wire in a cross-section perpendicular to the long side direction of Example 1. Detailed Implementation

[0033] The present invention will now be described in detail based on its embodiments.

[0034] The inventors of this application conducted repeated and in-depth research and discovered that by having a specified alloy composition, a metal structure with grains extending in one direction, and an average grain size of a specified value, it is possible to obtain an aluminum alloy material that not only has bending fatigue resistance far exceeding that of previous aluminum alloy materials, but also has bending fatigue resistance comparable to that of copper-based metal materials, and also has excellent elongation. Based on the above discovery, this invention was completed.

[0035] The aluminum alloy material of the embodiment has an alloy composition containing, by mass percent, 0.20 to 1.80% magnesium (Mg), 0.20 to 2.00% silicon (Si), and 0.01 to 1.50% iron (Fe), and also contains one or more elements selected from the group consisting of copper (Cu), silver (Ag), zinc (Zn), nickel (Ni), cobalt (Co), titanium (Ti), gold (Au), manganese (Mn), chromium (Cr), vanadium (V), zirconium (Zr), and tin (Sn): totaling 0.00 to 2.00%, with the balance being Al and unavoidable impurities, and has a fibrous metallic structure with grains extending in one direction. Furthermore, for aluminum alloy materials, in a cross section of the aluminum alloy material perpendicular to the long side direction of the aforementioned grain extension, the average grain size R1 of the grains present at a thickness position D, which is equivalent to 1 / 20 of the thickness of the aforementioned aluminum alloy material from the surface of the aforementioned aluminum alloy material, is 400 nm or less, and the ratio (R2 / R1) of the average grain size R2 of the grains present at the thickness center position C of the aforementioned aluminum alloy material to the aforementioned average grain size R1 at the aforementioned thickness position D is 1.8 or more.

[0036] Here, in the elemental composition of the aforementioned alloy, the elemental component whose lower limit is recorded as "0.00%" refers to the component that is optionally added to the aluminum alloy material as appropriate and as needed. That is, when the lower limit of the elemental component is "0.00%", it means that the elemental component is not contained in the aluminum alloy material or its content is below the detection limit value.

[0037] Furthermore, in this specification, the term "grain" refers to the portion enclosed by orientation difference boundaries. Here, "orientation difference boundary" refers to the boundary where the contrast (channel effect contrast) changes discontinuously when observing metal microstructure using methods such as scanning transmission electron microscopy (STEM) and scanning ion microscopy (SIM). Additionally, the dimension perpendicular to the long side direction of the grain extension corresponds to the spacing of the orientation difference boundaries.

[0038] (1) Grain state of aluminum alloy materials

[0039] use Figure 1 and Figure 2 The state of the grains in the aluminum alloy material of the embodiment and their function are explained.

[0040] Aluminum alloy materials possess a fibrous metallic structure with grains extending uniformly in one direction. Furthermore, the grains in this aluminum alloy material are fibrous and exhibit the following characteristics: in a cross-section perpendicular to the long side of the grain extension direction, the average grain size R1 of the grains present at thickness position D is less than 400 nm, and grains with a larger grain size R2 are present at the thickness center position C. These fine grains, extending uniformly in one direction in a fibrous manner, create a novel metallic structure, when observed in a cross-section of the aluminum alloy material perpendicular to the long side of the grain extension direction. The grains present on the surface side (thickness position D) have different grain sizes than the grains present at the thickness center position C. This results in a gradient grain size distribution, a novel metallic structure not found in conventional aluminum alloy materials.

[0041] Here, the aforementioned thickness position D refers to a position in a cross-section of the aluminum alloy material perpendicular to the long side direction of the grain extension, at a point equivalent to 1 / 20 of the thickness of the aluminum alloy material from its surface. Furthermore, thickness, for example, refers to... Figure 1 In the case where the aluminum alloy material is wire as shown in (a), the corresponding wire diameter φ is... Figure 1 (b) shows the case where the aluminum alloy material is a sheet material, which corresponds to the sheet thickness t. For example, Figure 1 In the case where the aluminum alloy material is wire as shown in (a), the thickness position D is the location within the region divided into concentric rings relative to the center of the aluminum alloy material in the aforementioned cross-section, and the thickness center position C is the location within the region enclosed by a circle whose diameter is 2 / 10 of the thickness (diameter is 2φ / 10) of the thickness, containing the center of the thickness of the aluminum alloy material in the aforementioned cross-section. Furthermore, Figure 1 (b) In the case where the aluminum alloy material is a sheet, the thickness position D is the location within the area divided by rectangles parallel to the upper and lower surfaces of the aluminum alloy material in the aforementioned cross section. The thickness center position C is the location within the area divided by a rectangle in the aforementioned cross section, which includes a center line defined between the upper and lower surfaces of the aluminum alloy material, and whose shorter side is 2 / 10 of the thickness (the shorter side is 2t / 10). Furthermore, the so-called average grain sizes R1 and R2 refer to the diameters of the equivalent circles as follows: in a cross section perpendicular to the direction of the long side of the grain extension, the area of ​​each grain is calculated based on the region enclosed by the outline of each grain, and the equivalent circle is calculated.

[0042] As described above, the aluminum alloy material exhibits a grain size gradient as follows: the grain size increases towards the thickness center C, and decreases from the thickness center C towards the surface. This aluminum alloy material possesses a fibrous metallic structure with grains extending in one direction, and is controlled such that, in a cross-section perpendicular to this direction, the average grain size R1 at thickness position D is 400 nm or less, and the ratio (R2 / R1) of the average grain size R2 at thickness center C to the average grain size R1 at thickness position D is 1.8 or more. Therefore, the aluminum alloy material can simultaneously achieve high bending fatigue resistance comparable to copper-based metals, and a certain elongation (e.g., a repeated fracture count of over 100,000 cycles when repeatedly bent with a bending strain amplitude ±0.25%, and an elongation of over 3% based on tensile tests). It exhibits excellent fatigue resistance, particularly for repeated bending deformation.

[0043] Furthermore, when the grain size of the aluminum alloy material surface layer, including the surface and thickness position D, is made fine, it not only improves fatigue characteristics, but also effectively improves grain boundary corrosion, reduces the roughness of the aluminum alloy material surface after plastic processing, and reduces collapse and flash during shearing, thus comprehensively improving the properties of aluminum alloy materials.

[0044] The microstructure of aluminum alloys is fibrous, consisting of elongated grains that extend in a fibrous manner along a single direction. Here, "single direction" refers to the processing direction of the aluminum alloy. For example, in the case of aluminum alloy wire, one direction corresponds to the drawing direction; in the case of aluminum alloy sheet or foil, one direction corresponds to the rolling direction.

[0045] The aforementioned direction preferably corresponds to the long side direction of the aluminum alloy material. That is, generally, for aluminum alloy materials, as long as they are not monolithically processed with a dimension shorter than the dimension perpendicular to their processing direction, their processing direction corresponds to their long side direction. For example, when the aluminum alloy material is in the form of wire, one direction corresponds to the long side direction of the wire.

[0046] Furthermore, in the cross-section of the aluminum alloy material perpendicular to the long side direction of grain extension, the average grain size R1 at the thickness position D is preferably 400 nm or less, more preferably 230 nm or less, even more preferably 210 nm or less, particularly preferably 180 nm or less, and even more preferably 150 nm or less. In the fibrous metallic structure of such an aluminum alloy material, the grain size (the dimension perpendicular to the long side direction of grain extension) extending in one direction is small. Therefore, crystal slip accompanying repeated deformation can be effectively suppressed, and higher bending fatigue resistance than before can be achieved. It should be noted that the lower limit of the average grain size R1 at the thickness position D is preferred from the perspective of achieving high bending fatigue resistance, but as a manufacturing or physical limit, it is, for example, 20 nm.

[0047] Furthermore, in the cross-section of the aluminum alloy material perpendicular to the long side direction of grain extension, the ratio (R2 / R1) of the average grain size R2 at the thickness center C to the average grain size R1 at the thickness position D is 1.8 or more, preferably 2.0 or more, more preferably 2.2 or more, even more preferably 2.4 or more, and particularly preferably 2.5 or more. As described above, the grain size at the thickness center C is larger than that near the surface of the cross-section, thus allowing for an increase in dislocations during tensile deformation. This results in high flexural fatigue resistance and a certain elongation. It should be noted that the upper limit of the above ratio (R2 / R1) is preferred from the perspective of simultaneously achieving high flexural fatigue resistance and elongation, but as a manufacturing limit, it is, for example, 20.0.

[0048] Furthermore, in the cross-section of the aluminum alloy material parallel to the long side direction of the grain extension, the long side dimension of the grains present in the aluminum alloy material, measured along the long side direction, is not particularly specified, but is preferably 1200 nm or more, more preferably 1700 nm or more, and even more preferably 2200 nm or more.

[0049] Furthermore, in a cross-section of an aluminum alloy material parallel to the long side direction of grain extension, for grains present at thickness position D, the aspect ratio (L1 / L2) of the long side dimension L1 measured along the long side direction and the short side dimension L2 measured along the direction perpendicular to the long side direction is preferably 10 or more, more preferably 20 or more. When the aforementioned aspect ratio (L1 / L2) is within the above range, the bending fatigue resistance is improved.

[0050] The mechanisms by which the aforementioned grain state improves bending fatigue resistance include, for example: in the surface of aluminum alloys with the greatest bending strain, the grains are fibrous with a large aspect ratio, which reduces the number of grain boundaries that can become crack initiation points on the surface, thus making it less prone to crack formation; since the short-side dimension L2 of the grains is small, dislocations are less likely to move, thus absorbing all or most of the bending strain as elastic strain; the formation of step-like portions that serve as crack initiation points on the surface of aluminum alloys is less likely, and when cracks do occur, the grain boundaries act as obstacles to crack propagation; and so on. These mechanisms are believed to work synergistically.

[0051] In addition, the mechanisms by which the above-mentioned grain state increases the tensile elongation can be cited as follows: the average grain size at the thickness center C is large, the accumulated lattice strain is small, and therefore it has a large plastic deformation capacity, which can fully absorb the plastic deformation during tensile deformation; by making the average grain size at the thickness position D small, the tensile strain can be absorbed in the form of elastic deformation; and so on.

[0052] (2) Alloy composition of aluminum alloy materials

[0053] Next, the alloy composition and function of the aluminum alloy material in the embodiments will be explained.

[0054] (Required ingredient)

[0055] Aluminum alloy materials contain 0.20–1.80% Mg, 0.20–2.00% Si, and 0.01–1.50% Fe by mass. Hereinafter, mass percent will be simply expressed as %.

[0056] <Mg:0.20~1.80%>

[0057] Mg has the function of strengthening aluminum by solid solution in aluminum matrix, as well as the function of refining crystals, and it also has the function of improving tensile strength and bending fatigue resistance through synergistic effect with Si. In addition, Mg has the function of improving tensile strength and elongation when it forms Mg-Si clusters as solute atomic clusters. However, if the Mg content is less than 0.20%, the above effects are insufficient. In addition, if the Mg content is higher than 1.80%, crystals are formed, and the workability (wire drawing workability, bending workability, etc.) is reduced. Therefore, the Mg content is set at 0.20-1.80%, preferably 0.40-1.00%.

[0058] <Si:0.20~200%>

[0059] Si (Si) strengthens aluminum by solid solution in the aluminum matrix and contributes to crystal refinement. It also improves tensile strength and flexural fatigue resistance through a synergistic effect with Mg. Furthermore, Si enhances tensile strength and elongation when it forms Mg-Si or Si-Si clusters as solute atom clusters. However, if the Si content is below 0.20%, these effects are insufficient. Conversely, if the Si content is above 2.00%, crystals form, reducing processability. Therefore, the Si content is set to 0.20–2.00%, preferably 0.40–1.00%.

[0060] <Fe:0.01~1.50%>

[0061] Fe crystallizes or precipitates in the form of aluminum, essential additives, and intermetallic compounds, such as Al-Fe, Al-Fe-Si, and Al-Fe-Si-Mg systems, during casting and homogenization heat treatment. In this specification, intermetallic compounds mainly composed of Fe and Al, as described above, are referred to as Fe-based compounds. Fe-based compounds contribute to grain refinement and improve tensile strength. Furthermore, even Fe dissolved in aluminum contributes to improved tensile strength. These effects are insufficient if the Fe content is below 0.01%. Conversely, if the Fe content is above 1.50%, there is an excess of Fe-based compounds, reducing workability. It should be noted that slow cooling rates during casting lead to sparse dispersion of Fe-based compounds, increasing the negative impact. Therefore, the Fe content is set at 0.01–1.50%, preferably 0.02–0.80%, more preferably 0.03–0.50%, further preferably 0.04–0.30%, and even more preferably 0.05–0.25%.

[0062] The mechanisms by which the aforementioned components contribute to crystal miniaturization include, for example: the large difference between the atomic radii of the aforementioned components and those of aluminum, which reduces the energy of grain boundaries; the high diffusion coefficient of the aforementioned components, which reduces the migration rate of grain boundaries when they enter them, thereby improving the crystal miniaturization effect and suppressing the coarsening of the crystal structure during repeated deformation; and the strong interaction with pores, which traps the pores and thus delays diffusion; and so on. These mechanisms are believed to work synergistically.

[0063] (Optional ingredients)

[0064] In addition to Mg, Si, and Fe, which are essential additives, aluminum alloy materials also contain at least 2.00% of one or more elements selected from the group consisting of Cu, Ag, Zn, Ni, Ti, Co, Au, Mn, Cr, V, Zr, and Sn as optional additives.

[0065] <Selected from one or more elements in the group consisting of Cu, Ag, Zn, Ni, Ti, Co, Au, Mn, Cr, V, Zr, and Sn: Total 0.00% to 2.00%>

[0066] Cu, Ag, Zn, Ni, Ti, Co, Au, Mn, Cr, V, Zr, and Sn are all elements that are particularly effective in improving heat resistance. From the viewpoint of maximizing this effect, it is preferable to set the total content of these optional additives to 0.06% or more. However, if the total content of these optional additives is set to be higher than 2.00%, processability decreases. Therefore, the total content of one or more elements selected from the group consisting of Cu, Ag, Zn, Ni, Ti, Co, Au, Mn, Cr, V, Zr, and Sn is set to 0.00% to 2.00%, preferably 0.06% to 2.00%, and more preferably 0.30% to 1.20%. It should be noted that the total content of these elements can be set to 0.00%. Furthermore, these elements can be added individually or in combination of two or more elements.

[0067] Furthermore, considering corrosion resistance in corrosive environments, aluminum alloy materials preferably contain one or more elements selected from the group consisting of Zn, Ni, Ti, Co, Mn, Cr, V, Zr, and Sn. Moreover, if the total content of these elements is less than 0.06%, the corrosion resistance is insufficient. Additionally, if the total content of these elements is greater than 2.00%, the workability decreases. Therefore, from the viewpoint of corrosion resistance, the total content of one or more elements selected from the group consisting of Zn, Ni, Ti, Co, Mn, Cr, V, Zr, and Sn is preferably 0.06% to 2.00%, more preferably 0.30% to 1.20%.

[0068] <Cu:0.00~2.00%>

[0069] Cu is an element that particularly enhances heat resistance. From the viewpoint of maximizing this effect, it is preferable to set the Cu content to 0.06% or more. However, if the Cu content is set above 2.00%, processability and corrosion resistance decrease. Therefore, the Cu content is preferably 0.00% to 2.00%, more preferably 0.06% to 2.00%, and even more preferably 0.30% to 1.20%. It should be noted that the Cu content can also be set to 0.00%.

[0070] <Ag:0.00~2.00%>

[0071] Ag is an element that particularly improves heat resistance. From the viewpoint of maximizing this effect, it is preferable to set the Ag content to 0.06% or more. However, if the Ag content is set above 2.00%, processability decreases. Therefore, the Ag content is preferably 0.00% to 2.00%, more preferably 0.06% to 2.00%, and even more preferably 0.30% to 1.20%. It should be noted that the Ag content can be set to 0.00%.

[0072] <Zn:0.00~2.00%>

[0073] Zinc (Zn) is an element that particularly improves heat resistance. From the viewpoint of maximizing this effect, it is preferable to set the Zn content to 0.06% or more. However, if the Zn content is set above 2.00%, processability decreases. Therefore, the Zn content is preferably 0.00% to 2.00%, more preferably 0.06% to 2.00%, and even more preferably 0.30% to 1.20%. It should be noted that the Zn content can be set to 0.00%. Furthermore, considering corrosion resistance in corrosive environments, aluminum alloy materials preferably contain Zn. Moreover, if the Zn content is below 0.06%, the corrosion resistance effect is insufficient. Additionally, if the Zn content is above 2.00%, processability decreases. Therefore, from the viewpoint of corrosion resistance, the Zn content is preferably 0.06% to 2.00%, more preferably 0.30% to 1.20%.

[0074] <Ni:0.00~2.00%>

[0075] Ni is an element that particularly improves heat resistance. From the viewpoint of maximizing this effect, it is preferable to set the Ni content to 0.06% or more. However, if the Ni content is set above 2.00%, processability decreases. Therefore, the Ni content is preferably 0.00% to 2.00%, more preferably 0.06% to 2.00%, and even more preferably 0.30% to 1.20%. It should be noted that the Ni content can be set to 0.00%. Furthermore, considering corrosion resistance in corrosive environments, aluminum alloy materials preferably contain Ni. Moreover, if the Ni content is below 0.06%, the corrosion resistance effect is insufficient. Additionally, if the Ni content is above 2.00%, processability decreases. Therefore, from the viewpoint of corrosion resistance, the Ni content is preferably 0.06% to 2.00%, more preferably 0.30% to 1.20%.

[0076] <Ti:0.00~2.00%>

[0077] Ti is an element that refines the crystal structure during casting and improves heat resistance. From the viewpoint of maximizing these effects, it is preferable to set the Ti content to 0.005% or more. However, if the Ti content is set above 2.00%, the workability decreases. Therefore, the Ti content is preferably 0.00% to 2.00%, more preferably 0.06% to 2.00%, and even more preferably 0.30% to 1.20%. It should be noted that the Ti content can be set to 0.00%. Furthermore, considering corrosion resistance in corrosive environments, aluminum alloy materials preferably contain Ti. Moreover, if the Ti content is below 0.06%, the corrosion resistance effect is insufficient. Additionally, if the Ti content is above 2.00%, the workability decreases. Therefore, from the viewpoint of corrosion resistance, the Ti content is preferably 0.06% to 2.00%, more preferably 0.30% to 1.20%.

[0078] <Co:0.00~2.00%>

[0079] Co is an element that particularly improves heat resistance. From the viewpoint of maximizing this effect, it is preferable to set the Co content to 0.06% or more. However, if the Co content is set above 2.00%, processability decreases. Therefore, the Co content is preferably 0.00% to 2.00%, more preferably 0.06% to 2.00%, and even more preferably 0.30% to 1.20%. It should be noted that the Co content can be set to 0.00%. Furthermore, considering corrosion resistance in corrosive environments, aluminum alloy materials preferably contain Co. Moreover, if the Co content is below 0.06%, the corrosion resistance effect is insufficient. Additionally, if the Co content is above 2.00%, processability decreases. Therefore, from the viewpoint of corrosion resistance, the Co content is preferably 0.06% to 2.00%, more preferably 0.30% to 1.20%.

[0080] <Au:0.00~2.00%>

[0081] Au is an element that particularly improves heat resistance. From the viewpoint of maximizing this effect, it is preferable to set the Au content to 0.06% or more. However, if the Au content is set above 2.00%, processability decreases. Therefore, the Au content is preferably 0.00% to 2.00%, more preferably 0.06% to 2.00%, and even more preferably 0.30% to 1.20%. It should be noted that the Au content can be set to 0.00%.

[0082] <Mn:0.00~2.00%>

[0083] Mn is an element that particularly improves heat resistance. From the viewpoint of maximizing this effect, it is preferable to set the Mn content to 0.06% or more. However, if the Mn content is set above 2.00%, processability decreases. Therefore, the Mn content is preferably 0.00% to 2.00%, more preferably 0.06% to 2.00%, and even more preferably 0.30% to 1.20%. It should be noted that the Mn content can be set to 0.00%. Furthermore, considering corrosion resistance in corrosive environments, aluminum alloy materials preferably contain Mn. Moreover, if the Mn content is below 0.06%, the corrosion resistance effect is insufficient. Additionally, if the Mn content is above 2.00%, processability decreases. Therefore, from the viewpoint of corrosion resistance, the Mn content is preferably 0.06% to 2.00%, more preferably 0.30% to 1.20%.

[0084] <Cr:0.00~2.00%>

[0085] Cr is an element that particularly improves heat resistance. From the viewpoint of maximizing this effect, it is preferable to set the Cr content to 0.06% or more. However, if the Cr content is set above 2.00%, workability decreases. Therefore, the Cr content is preferably 0.00% to 2.00%, more preferably 0.06% to 2.00%, and even more preferably 0.30% to 1.20%. It should be noted that the Cr content can be set to 0.00%. Furthermore, considering corrosion resistance in corrosive environments, aluminum alloy materials preferably contain Cr. Moreover, if the Cr content is below 0.06%, the corrosion resistance effect is insufficient. Additionally, if the Cr content is above 2.00%, workability decreases. Therefore, from the viewpoint of corrosion resistance, the Cr content is preferably 0.06% to 2.00%, more preferably 0.30% to 1.20%.

[0086] <V:0.00~2.00%>

[0087] V is an element that particularly improves heat resistance. From the viewpoint of maximizing this effect, it is preferable to set the V content to 0.06% or more. However, if the V content is set above 2.00%, processability decreases. Therefore, the V content is preferably 0.00% to 2.00%, more preferably 0.06% to 2.00%, and even more preferably 0.30% to 1.20%. It should be noted that the V content can be set to 0.00%. Furthermore, considering corrosion resistance in corrosive environments, aluminum alloy materials preferably contain V. Moreover, if the V content is below 0.06%, the corrosion resistance effect is insufficient. Additionally, if the V content is above 2.00%, processability decreases. Therefore, from the viewpoint of corrosion resistance, the V content is preferably 0.06% to 2.00%, more preferably 0.30% to 1.20%.

[0088] <Zr:0.00~2.00%>

[0089] Zr is an element that particularly improves heat resistance. From the viewpoint of maximizing this effect, it is preferable to set the Zr content to 0.06% or more. However, if the Zr content is set above 2.00%, processability decreases. Therefore, the Zr content is preferably 0.00% to 2.00%, more preferably 0.06% to 2.00%, and even more preferably 0.30% to 1.20%. It should be noted that the Zr content can be set to 0.00%. Furthermore, considering corrosion resistance in corrosive environments, aluminum alloy materials preferably contain Zr. Moreover, if the Zr content is below 0.06%, the corrosion resistance effect is insufficient. Additionally, if the Zr content is above 2.00%, processability decreases. Therefore, from the viewpoint of corrosion resistance, the Zr content is preferably 0.06% to 2.00%, more preferably 0.30% to 1.20%.

[0090] <Sn:0.00~2.00%>

[0091] Sn is an element that particularly improves heat resistance. From the viewpoint of maximizing this effect, it is preferable to set the Sn content to 0.06% or more. However, if the Sn content is set above 2.00%, processability decreases. Therefore, the Sn content is preferably 0.00% to 2.00%, more preferably 0.06% to 2.00%, and even more preferably 0.30% to 1.20%. It should be noted that the Sn content can be set to 0.00%. Furthermore, considering corrosion resistance in corrosive environments, aluminum alloy materials preferably contain Sn. Moreover, if the Sn content is below 0.06%, the corrosion resistance effect is insufficient. Additionally, if the Sn content is above 2.00%, processability decreases. Therefore, from the viewpoint of corrosion resistance, the Sn content is preferably 0.06% to 2.00%, more preferably 0.30% to 1.20%.

[0092] <Balance: Al and unavoidable impurities>

[0093] The balance other than the aforementioned components includes Al and unavoidable impurities. Unavoidable impurities refer to impurities that are unavoidably included in the manufacturing process. Depending on their content, unavoidable impurities can also be a significant factor in reducing processability; therefore, it is preferable to suppress the content of unavoidable impurities to a certain extent while also considering the reduction in processability. Examples of components that can be listed as unavoidable impurities include elements such as boron (B), bismuth (Bi), lead (Pb), gallium (Ga), and strontium (Sr). It should be noted that the upper limit for the content of unavoidable impurities can be set to 0.05% or less for each of the aforementioned components, and 0.15% or less for the total of the aforementioned components.

[0094] Such aluminum alloy materials can be achieved by combining and controlling the alloy composition and manufacturing process.

[0095] (3) Properties of aluminum alloy materials

[0096] Next, the characteristics of the aluminum alloy material in the embodiments will be explained.

[0097] [Resistance to bending fatigue]

[0098] As a benchmark for flexural fatigue resistance, the strain amplitude at room temperature is set to ±0.17% and ±0.25%. Flexural fatigue resistance varies with strain amplitude. A larger strain amplitude results in a shorter fatigue life, while a smaller strain amplitude results in a longer fatigue life. The strain amplitude can be determined using methods described later. Figure 3 The apparatus shown is used to determine this.

[0099] [Elongation]

[0100] Elongation was determined according to JIS Z2241:2011. Detailed test conditions are described in the Examples section below.

[0101] For aluminum alloy materials, especially when they are in the form of wire, the elongation is preferably 3.0% or more. Furthermore, the elongation is more preferably 3.5% or more, even more preferably 4.0% or more, particularly preferably 5.0% or more, and even more preferably 6.0% or more. Aluminum alloy materials with such a certain elongation reduce the likelihood of wire breakage during processing, cable manufacturing, and use, thus achieving high reliability. It should be noted that there is no particular upper limit to the elongation of the aluminum alloy material; for example, it could be 20.0%.

[0102] (4) Applications of aluminum alloy materials

[0103] For the aluminum alloy material used in the embodiments, all applications using copper-based and aluminum-based materials, especially those involving repetitive motion, are applicable. Specifically, aluminum alloy materials are preferably used for conductive components such as wires and cables; battery components such as screens and meshes for current collectors; spring components for electrical contacts such as connectors and terminals; bonding wires for semiconductors; and coils used in generators and motors.

[0104] More specific examples of applications for conductive components include: power cables such as thick rubber flexible cables, overhead transmission lines, OPGW, underground wires, and submarine cables; communication cables such as telephone cables and coaxial cables; robot cables; wired drone cables; EV / HEV charging cables; offshore wind power twisted cables; elevator cables; umbilical cables; tram overhead lines; jumper wires and other vehicle wiring harnesses; machine wiring harnesses such as automotive wiring harnesses; ship wiring harnesses; aircraft wiring harnesses and other transmission wires; busbars; lead frames; flexible flat cables; lightning rods; antennas; connectors; terminals; and cable bundles.

[0105] More specific examples of applications for spring components include spring electrodes, terminals, connectors, and springs for semiconductor probes.

[0106] In addition to the above, aluminum alloy materials are also preferred as metal fibers added to make resin-based materials, plastic materials, cloth, etc. conductive, or to control strength and elastic modulus.

[0107] (5) Manufacturing methods of aluminum alloy materials

[0108] For aluminum alloys, such as Al-Mg-Si alloy wires, a balance between high flexural fatigue resistance and elongation can be achieved by clustering small grains near the surface where bending strain increases and placing larger grains at the thickness center C where bending strain is low. Therefore, this approach differs significantly from conventional aluminum alloy manufacturing methods that typically involve the precipitation and solidification of Mg-Si compounds or crystal refinement.

[0109] In the preferred manufacturing method of the aluminum alloy material of the embodiment, the aluminum alloy raw material having a specified alloy composition is subjected to cold working with a machining degree of 5 or more as the final processing [1]. In addition, as needed, a pretreatment process to refine the grain size of the surface layer can be performed before cold working [1] [2], and tempering and annealing can be performed after cold working [1] [3]. The following is a detailed description.

[0110] Generally, when stress is repeatedly applied to a metallic material, crystal slip, the root cause of deformation in the metal crystals, occurs simultaneously with elastic deformation. The more easily a metallic material exhibits crystal slip, the more likely it is to develop crack initiation points on its surface, thus resulting in lower resistance to bending fatigue. Therefore, suppressing crystal slip within the metal structure is crucial for achieving high resistance to bending fatigue in metallic materials. The presence of grain boundaries within the metal structure is a significant factor hindering such crystal slip. These grain boundaries, when stress is applied to the metallic material, can suppress the propagation of crystal slip within the metal structure, thereby improving the fatigue properties of the metallic material.

[0111] Therefore, to achieve a long fatigue life for metallic materials, it is considered preferable to introduce grain boundaries into the metal structure at a high density, i.e., to aggregate small grains. Here, as a mechanism for the formation of grain boundaries, for example, the splitting of metal crystals accompanying the deformation of the metal structure can be considered as described below.

[0112] Typically, within polycrystalline materials, the stress state becomes a complex multiaxial state due to the differences in orientation between adjacent grains, the spatial distribution of strain near the surface in contact with the processing tool, and the bulk interior. As a result of these effects, grains with a single orientation before deformation split into multiple orientations during deformation, forming orientation difference boundaries between the split crystals.

[0113] However, the resulting orientation difference boundaries possess interfacial energy due to their structure, which deviates from the typical 12-coordinated densest atomic arrangement. Therefore, it is believed that in typical metallic structures, if grain boundaries reach a certain density, the increased internal energy becomes the driving force, leading to dynamic or static recovery and recrystallization. Thus, it is generally believed that even with increased deformation, the grain boundary density will eventually reach saturation due to the simultaneous increase and decrease of grain boundaries.

[0114] This phenomenon is consistent with the relationship between workability and tensile strength in conventional metallic structures like pure aluminum and pure copper. While pure aluminum and pure copper, as conventional metallic structures, exhibit increased tensile strength (solidification) at lower workability levels, there is a trend towards increasing solidification saturation with increasing workability. Here, it is assumed that workability corresponds to the amount of deformation applied to the aforementioned metallic structure, and solidification saturation corresponds to grain boundary density saturation.

[0115] Furthermore, while simple machining increases resistance to bending fatigue, it also reduces ductility, leading to problems such as wire breakage during machining and use. This is believed to be because the introduction of a large number of dislocations into the crystal results in dislocation density saturation, making it impossible to allow for higher degrees of plastic deformation.

[0116] In contrast, it can be seen that in the aluminum alloy material of the embodiment, while the workability increases, the grain boundary density in the surface layer increases continuously, i.e., the aggregation of small grains continues to occur, and the bending fatigue resistance is continuously improved. This is believed to be because by giving the aluminum alloy material the aforementioned alloy composition, it is possible to promote an increase in grain boundary density, and even if the grain boundaries within the metal structure reach a certain density, the increase in internal energy can be suppressed. As a result, it is believed that recovery and recrystallization within the metal structure can be prevented, and the grain boundaries within the metal structure can be effectively increased.

[0117] Although the mechanism of crystal miniaturization caused by the composite addition of Mg and Si may not be clear, it is believed to be due to: (i) Mg, which has a strong interaction with lattice defects such as dislocations, promotes crystal miniaturization, thereby promoting crystal breakage; (ii) Mg atoms with atomic radii larger than Al atoms and Si atoms with atomic radii smaller than Al atoms mitigate the mismatch of atomic arrangement at grain boundaries, thereby effectively suppressing the increase in internal energy accompanying processing.

[0118] Furthermore, in the aluminum alloy material of the embodiment, particularly due to the introduction of plastic deformation on its surface, there are very fine crystals near the surface layer, while on the other hand, larger crystals remain at the thickness center C. Because of this crystalline structure, the fine crystals on the surface layer effectively function during bending deformation, while the large crystals at the thickness center C effectively function for elongation.

[0119] In the method for manufacturing aluminum alloy materials according to the embodiments, the degree of processing in cold working [1] is set to 5 or more. In particular, by processing with a large degree of processing, it is possible to promote the splitting of metal crystals that occur with the deformation of the metal structure, and to introduce grain boundaries into the interior of the aluminum alloy material at a high density. As a result, small grains aggregate on the surface of the aluminum alloy material, and the bending fatigue resistance is greatly improved. Such a degree of processing is preferably set to 6 or more, and more preferably to 7 or more. In addition, there is no particular upper limit for the degree of processing, and it is usually 15 or less.

[0120] It should be noted that the degree of processing η is represented by the following formula (1) when the cross-sectional area before processing is set as s1 and the cross-sectional area after processing is set as s2 (s1>s2).

[0121] Processing degree (dimensionless): η=ln(s1 / s2)···(1)

[0122] The method of cold working [1] can be appropriately selected according to the shape of the aluminum alloy material to be targeted (wire, bar, sheet, strip, foil, etc.), for example, cassette roller dies, grooved roller rolling, round wire rolling, drawing based on dies, swaging, etc. In addition, the various conditions in the processing described above (type of lubricating oil, processing speed, processing heat, etc.) can be appropriately adjusted within the known range.

[0123] Furthermore, a pretreatment process [2] can be performed before cold working [1]. Examples of pretreatment processes [2] include shot peening, extrusion, die forging, skin pass, rolling, and recrystallization. Thus, a gradient in grain size can be created between the surface and interior of the aluminum alloy material before cold working [1], resulting in a finer crystal structure after cold working [1] and a larger gradient in grain size. The conditions in the above processes (processing speed, processing heat generation, temperature, etc.) can be appropriately adjusted within known ranges.

[0124] Aluminum alloy raw materials only need to have the above-mentioned alloy composition, and there are no special restrictions. For example, extruded materials, cast materials, hot-rolled materials, cold-rolled materials, etc. can be appropriately selected according to the purpose of use.

[0125] Alternatively, tempering annealing [3] can be performed after cold working [1] with the aim of relieving residual stress and increasing elongation. The treatment temperature of tempering annealing [3] is set to 50 to 200°C. If the treatment temperature of tempering annealing [3] is below 50°C, it is difficult to obtain the effect described above. If it is above 200°C, grain growth will occur due to recovery and recrystallization, and the bending fatigue resistance will decrease. In addition, the holding time of tempering annealing [3] is preferably 1 to 48 hours. It should be noted that the conditions of such heat treatment can be appropriately adjusted according to the type and amount of unavoidable impurities and the solid solution and precipitation state of the aluminum alloy raw material.

[0126] As described above, aluminum alloy raw materials can be processed with high machinability using methods such as die drawing and rolling. As a result, long-length aluminum alloy materials can be obtained. On the other hand, conventional aluminum alloy manufacturing methods such as powder sintering, compression torsion, high pressure torsion (HPT), forging, and equal channel angular pressing (ECAP) make it difficult to obtain such long-length aluminum alloy materials. The aluminum alloy material of the embodiment is preferably manufactured in a length of 10 m or more. It should be noted that the upper limit of the length of the aluminum alloy material during manufacturing is not specifically set, but considering workability, it is preferably set to 50,000 m.

[0127] Furthermore, for the aluminum alloy material of the embodiment, increasing the machinability is effective in refining the grain size of its surface layer. Therefore, when manufacturing wires, the finer the diameter, the easier it is to achieve the structure of the aluminum alloy material of this embodiment; similarly, when manufacturing sheets or foils, the thinner the thickness, the easier it is to achieve the structure of the aluminum alloy material of the embodiment.

[0128] Especially when the wire is made of aluminum alloy, its diameter is preferably 1.50 mm or less, more preferably 0.75 mm or less, even more preferably 0.30 mm or less, and particularly preferably 0.10 mm or less. It should be noted that the lower limit of the wire diameter is not specifically set, but considering factors such as workability, it is preferably 0.01 mm.

[0129] Furthermore, when the aluminum alloy material is sheet metal, its thickness is preferably 2.00 mm or less, more preferably 1.50 mm or less, even more preferably 1.00 mm or less, and particularly preferably 0.50 mm or less. It should be noted that the lower limit of the sheet thickness is not specifically set, but considering workability, it is preferably 0.02 mm.

[0130] As mentioned above, aluminum alloy materials are processed to be thinner or finer, but multiple such aluminum alloy materials can also be prepared and joined together to make them thicker or thicker for the intended use. It should be noted that known methods can be used for joining, such as pressing, welding, adhesive-based joining, friction stirring joining, etc. In addition, when the aluminum alloy material is a wire, multiple strands can be bundled and twisted together to form an aluminum alloy strand for the intended use. It should be noted that the above-mentioned tempering and annealing [3] can also be performed after the aluminum alloy material that has undergone the above-mentioned cold working [1] has been processed based on joining or twisting.

[0131] According to the embodiments described above, using the manufacturing method described above, it is possible to manufacture an aluminum alloy material having a specified alloy composition and a metallic structure with elongated grains aligned in one direction. In this aluminum alloy material, the average grain size R1 at the thickness position D is 400 nm or less, and the ratio (R2 / R1) is 1.8 or more. Therefore, the aluminum alloy material exhibits bending fatigue resistance characteristics far exceeding those of conventional aluminum alloy materials, comparable to copper-based metal materials, and also possesses excellent elongation. Such aluminum alloy wires can serve as a replacement for copper-based conductive components.

[0132] The embodiments have been described above, but the present invention is not limited to the above embodiments, but includes all the concepts of the present invention and all the ways contained in the claims, and various changes can be made within the scope of the present invention.

[0133] Example

[0134] Next, embodiments and comparative examples will be described, but the present invention is not limited to these embodiments.

[0135] (Examples 1-4)

[0136] Examples 1 to 4 use 10 mm diameter rods with the alloy composition shown in Table 1 as a pretreatment step [2] and shot peening with 1 mm diameter steel balls. Then, aluminum alloy wires with a diameter of 0.5 to 0.05 mm are produced under manufacturing conditions A to D shown in Table 1.

[0137] (Examples 5-8)

[0138] Examples 5-8 use 60 mm diameter bars with the alloy composition shown in Table 1 as a pretreatment step [2] to make the diameter of the bars 10 mm by die forging. Then, aluminum alloy wires with a wire diameter of 0.5-0.05 mm are produced under manufacturing conditions A-D shown in Table 1.

[0139] (Examples 9-15)

[0140] Examples 9 to 15 use 10 mm diameter bars with the alloy composition shown in Table 1 as a pretreatment process [2] and perform surface smoothing with a section shrinkage rate of <5% per pass using a wire drawing die. Then, aluminum alloy wires with a wire diameter of 0.5 to 0.05 mm are produced under the manufacturing conditions A to D, C, D and C shown in Table 1, respectively.

[0141] (Examples 16-18)

[0142] Examples 16-18 use 60 mm diameter bars with the alloy composition shown in Table 1 as a pretreatment step [2] to make the diameter of the bars 30 mm by die forging. Then, aluminum alloy wires with a wire diameter of 1.5-0.2 mm are produced under the manufacturing conditions A, A, and D shown in Table 1.

[0143] (Comparative Examples 1-4)

[0144] Comparative Examples 1 to 4 used 10 mm diameter rods with the alloy composition shown in Table 1 to produce aluminum alloy wires with diameters of 0.15 mm and 3.7 mm under the manufacturing conditions C, C, F, and C shown in Table 1, respectively.

[0145] (Comparative Example 5)

[0146] An aluminum alloy wire with a diameter of 0.08 mm is produced under manufacturing conditions E shown in Table 1, with the alloy composition shown in Table 1.

[0147] It should be noted that the manufacturing conditions A to F shown in Table 1 are described in detail below.

[0148] <Manufacturing Condition A>

[0149] The prepared bars were cold-worked to a machining degree of 6.0 [1]. It should be noted that no quenching and tempering was performed [3].

[0150] <Manufacturing Condition B>

[0151] The cold working [1] is performed with a degree of 8.5, otherwise it is performed under the same conditions as manufacturing condition A.

[0152] <Manufacturing Condition C>

[0153] The cold working [1] is performed with a degree of 11.0, otherwise it is performed under the same conditions as manufacturing condition A.

[0154] <Manufacturing Conditions D>

[0155] The prepared bar stock was cold-worked to a degree of 8.5 [1], and then tempered and annealed at a temperature of 100°C and a holding time of 5 hours [3].

[0156] <Manufacturing Condition F>

[0157] The cold working [1] is performed with a degree of 2.0, otherwise it is performed under the same conditions as manufacturing condition A.

[0158] (Comparative Example 5)

[0159] <Manufacturing Condition E>

[0160] A predetermined amount of aluminum (99.95% purity), magnesium (99.95% purity), silicon (99.99% purity), and iron (99.95% purity) were added to a graphite crucible and melted by stirring at 720°C under high-frequency induced heating to produce a molten metal with an alloy composition of Al - 0.60 wt% Mg - 0.30 wt% Si - 0.05 wt% Fe. The molten metal was then transferred to a container equipped with a graphite mold, and a 10 mm φ wire with a length of 100 mm was continuously cast at a casting speed of approximately 300 mm / min using the water-cooled graphite mold. Then, cumulative equivalent strain of 4.0 was introduced using the ECAP method. The recrystallization temperature for this stage was determined to be 300°C. Next, preheating was performed at 250°C for 2 hours in an inert gas atmosphere. Finally, a first wire drawing process with a workability of 0.34 was performed. The recrystallization temperature for this stage was determined to be 300°C. Then, a primary heat treatment was performed at 260°C for 2 hours in an inert gas atmosphere. Following this, a second drawing process with a machining degree of 9.3 was performed, drawing the wire through a water-cooled die at a speed of 500 mm / min. The recrystallization temperature for this stage was determined to be 280°C. Finally, a secondary heat treatment was performed at 220°C for 1 hour in an inert gas atmosphere to obtain an aluminum alloy wire with a diameter of 0.08 mm.

[0161] [evaluate]

[0162] The aluminum alloy wires obtained in the above examples and comparative examples were used to evaluate the properties described below. The evaluation conditions for each property are as follows. The results are shown in Table 1.

[0163] [1] Alloy composition

[0164] The measurements were performed according to JIS H1305:2005, using emission spectroscopy. It should be noted that the measurements were performed using an emission spectroscopy analyzer (manufactured by Hitachi High-Tech Science Corporation).

[0165] [2] Organizational observation

[0166] For observation of metallic structures, a scanning ion microscope (SMI3050TB, manufactured by Seiko Instruments Inc.) was used, employing the SIM (Scanning Ion Microscope) technique. Observation was performed at an accelerating voltage of 30 kV.

[0167] The specimens used for observation were obtained by the following operation: the aluminum alloy wire was cut with a thickness of 100nm±20nm using FIB (Focused Ion Beam) on the cross section parallel to the long side direction (processing direction) and the cross section perpendicular to the long side direction (processing direction), and then finished by ion milling.

[0168] In SIM observation, grayscale contrast is used to identify crystal orientation by varying contrast differences and grain boundaries by discontinuous contrast. It should be noted that, depending on electron beam diffraction conditions, sometimes there may be no difference in grayscale contrast even if crystal orientations differ. In such cases, the angle between the electron beam and the sample is changed by tilting the two orthogonal sample rotation axes within the electron microscope stage by ±3° each time, and the observation surface is photographed under various diffraction conditions to identify grain boundaries. It should be noted that the observation field of view is set to (15–40) μm × (15–40) μm, and observations are performed on the central portion and a portion at a thickness equivalent to 1 / 20 of the wire diameter from the wire surface in sections parallel and perpendicular to the processing direction. The magnification is appropriately adjusted according to the grain size.

[0169] Then, based on the images taken during SIM observation, it is determined whether there is a fibrous metallic structure in the cross-section of the aluminum alloy wire parallel to the long side direction (processing direction). If a fibrous metallic structure is observed, it is evaluated as "present" fibrous metallic structure.

[0170] Furthermore, in each observation field, any 100 grains were selected, and the average grain size R1, average grain size R2, long-side dimension L1, and short-side dimension L2 were measured. Then, based on the measured values, the average value of the 100 grains was calculated, yielding the average grain size R1, the aspect ratio (R2 / R1), and the length-to-width ratio (L1 / L2). It should be noted that for some comparative examples, since the average grain size R1 was significantly greater than 400 nm, grains larger than 400 nm were not selected, and the number of grains to be selected was reduced from 100, with each grain's average value calculated. Additionally, for cases where the aspect ratio (L1 / L2) was significantly greater than 10, the aspect ratio (L1 / L2) was consistently recorded as 10 or greater (represented as "≥10" in Table 1).

[0171] [3] Bending fatigue resistance

[0172] Using an alternating bending fatigue testing machine manufactured by Fujii Seiki Co., Ltd. (now FUJII Co., Ltd.), and a fixture capable of imparting bending strain amplitudes of ±0.17% and ±0.25%, repeated bending was performed to determine the number of repeated fractures. In this test, for each embodiment, four wires were prepared, and the tests were performed on each of the four wires individually, calculating the average value (N=4). Figure 3 As shown, aluminum alloy wire 1 is inserted with bending clamps 2 and 3 spaced approximately 1 mm apart, causing it to move repeatedly along bending clamps 2 and 3. For wires with coil marks, tensile strain is applied to straighten them, and repeated bending strain is applied to the fixed parts during the test. One end of aluminum alloy wire 1 is fixed to pressing clamp 5 in a manner that allows for repeated bending, and a weight 4, representing a load stress of 1 to 5% of the yield strength of aluminum alloy wire 1 (0.2%), is suspended at the other end. During the test, pressing clamp 5 moves, thus moving aluminum alloy wire 1 fixed thereto, enabling repeated bending. The following scheme is used: the repetition is performed at 100 times per minute; if aluminum alloy wire 1 breaks, weight 4 falls, and the counting stops. In addition, aluminum alloy wire 1 has higher strength than conventional aluminum alloy wire, and the weight 4 tends to become heavier than in typical repeated bending tests. Therefore, PTFE tape is attached to bending fixtures 2 and 3 to suppress wear.

[0173] Regarding the number of repeated fractures, with a strain amplitude of ±0.17%, 1 million cycles (10) will be achieved. 6 (100,000 cycles) or more is considered good. With a strain amplitude of ±0.25%, 100,000 cycles (10...) are considered good. 5 (Any one or more times) is considered good.

[0174] [4] Elongation

[0175] Tensile tests were conducted according to JIS Z2241:2001 using a precision universal testing machine (manufactured by Shimadzu Corporation) to determine the elongation. It should be noted that the test was performed with a distance of 10 cm between evaluation points and a deformation rate of 10 mm / min. Furthermore, for each embodiment, three wires were prepared, and the elongation of each wire was measured individually. The average value (N=3) was taken as the elongation of each wire. A higher elongation is preferred, and 3.0% or higher is considered acceptable.

[0176] [Table 1]

[0177]

[0178] A SIM image showing the morphology of the metallic structure of the aluminum alloy wire in Example 1 is presented. Figures 4-6 . Figure 4 A SIM image showing a cross-section of an aluminum alloy wire parallel to its long side. Figure 5 This is a SIM image showing a portion of the aluminum alloy wire at a thickness location corresponding to 1 / 20 of the wire diameter from the wire surface in a cross-section perpendicular to the long side direction. Figure 6 This is a SIM image showing the center of a cross-section of an aluminum alloy wire perpendicular to its long side.

[0179] like Figure 4 As shown, a fibrous metallic structure was observed in the aluminum alloy wire. Additionally, as... Figure 5 As shown, in the portion of the wire with a thickness equivalent to 1 / 20 of the wire diameter from the wire surface, the average grain size R1 is less than 400 nm. Figure 6 As shown, a larger grain size is maintained in the central part.

[0180] Explanation of reference numerals in the attached figures

[0181] 1 Aluminum alloy wire

[0182] 2, 3 Bending fixtures

[0183] 4 weights

[0184] 5. Push clamp

Claims

1. A method of manufacturing an aluminum alloy material, wherein, The aluminum alloy material has the following alloy composition: contains, in mass%, Mg: 0.29 to 1.00%, Si: 0.29 to 0.66%, Fe: 0.02 to 0.30%, and Ti: 0.02%, further contains one or more elements selected from the group of Ag, Ni, and Cr: total 0.00 to 2.00%, and the balance is Al and inevitable impurities; The aluminum alloy material has a fibrous metal structure in which grains extend in one direction, and in a cross section of the aluminum alloy material perpendicular to a long side direction in which the grains extend, an average grain size R1 of the grains present at a thickness position D corresponding to 1 / 20 of a thickness of the aluminum alloy material from a surface of the aluminum alloy material is 400 nm or less, and a ratio (R2 / R1) of an average grain size R2 of the grains present at a center position C of the thickness of the aluminum alloy material to the average grain size R1 at the thickness position D is 1.8 or more, The manufacturing method includes: a pre-treatment step in which at least one of shot peening, die forging, and skin pass rolling is performed to make the grain size of a surface layer fine; and a step in which cold working with a degree of working of 5 or more is performed, wherein the pre-treatment step is performed before the step in which the cold working is performed.

2. The method of producing an aluminum alloy material according to claim 1, wherein In a cross section of the aluminum alloy material parallel to the long side direction in which the grains extend, a ratio (L1 / L2) of a long side dimension L1 of the grains present at the thickness position D measured in the long side direction to a short side dimension L2 measured in a direction perpendicular to the long side direction is 10 or more.

3. The method of producing an aluminum alloy material according to claim 1 or 2, wherein The aluminum alloy material is a wire.

4. The method of producing an aluminum alloy material according to claim 3, wherein The wire has a wire diameter of 0.01 to 1.50 mm.

5. The method of producing an aluminum alloy material according to claim 1 or 2, wherein The aluminum alloy material is a plate.

6. The method of producing an aluminum alloy material according to claim 5, wherein The plate has a plate thickness of 0.02 to 2.00 mm.

Images