Aluminum extruded wire

Abstract

To provide an aluminum extruded wire that is made of aluminum having a small amount of alloy element added and has high strength and high strength uniformity in the longitudinal direction.SOLUTION: Provided is an aluminum extruded wire in which Fe, Cu, Ti, Mn, Mg, Cr, B, Ga, V and Zn with the total contained amount of 0.01 mass% or less and one or more selected from the group consisting of Ni, Y and Si are contained, and the balance of which is Al and unavoidable impurities, and in a cross section perpendicular to the longitudinal direction of the extruded wire, both the central measurement area including the center point of the cross section and the peripheral measurement area contacting the outer periphery of the cross section have an average crystal grain size measured by backscattered electron diffraction of 15 to 50 μm, respectively.SELECTED DRAWING: Figure 1B

Description

Technical Field

[0001] The present disclosure relates to an aluminum extrusion wire.

Background Art

[0002] Aluminum extruded products manufactured by extrusion technology have been known for a long time. For example, Non-Patent Document 1 discloses that in the extrusion molding of AA1100 series aluminum alloys, an extrusion temperature of 400 to 500°C and a container temperature of 360 to 460°C are suitable. Patent Document 1 relates to a high purity aluminum sputtering target, and it is described that an extruded product with a crystal grain size of 100 μm or less can be obtained by extruding high purity aluminum at a low temperature of 300°C or lower.

[0003] Patent Document 2 relates to a high electric conductivity and heat resistance iron-containing lightweight aluminum wire, and it is disclosed that the extrusion temperature is 300 to 450°C. Patent Document 3 relates to a method for manufacturing a rod for an aluminum wire, and it is disclosed that aluminum containing Ni: 40 to 60 ppm and Si: 5 to 10 ppm is extruded at a billet temperature of 360 to 380°C and a container temperature of 380 to 420°C.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0005]

Non-Patent Document 1

[0006] In typical aluminum alloys, strength is determined by precipitation strengthening and solid solution strengthening due to added elements. Therefore, by keeping the component composition constant, the strength can be made constant along the entire length of the aluminum alloy extruded wire.

[0007] Aluminum extruded wires used for overhead power lines, superconducting stabilizers, and fine wire processing utilize aluminum materials such as high-purity aluminum of 4N or higher, to which specific chemical components are intentionally added at a concentration of 1000 ppm or less by mass. In such aluminum extruded wires, the strength tends to be low because the amount of added elements is small. Furthermore, the strength cannot be controlled by the added elements, and there is a risk that the strength will fluctuate along the length of the aluminum extruded wire. For example, extruded wires formed immediately after the start of extrusion (start of extrusion) have relatively high strength, and then the strength gradually decreases, with extruded wires formed towards the end of extrusion (end of extrusion) (sometimes referred to as the "tail end of the extruded wire") showing a significant decrease in strength.

[0008] However, neither Non-Patent Document 1 nor Patent Documents 1-3 consider the uniformity of strength along the length of the aluminum extruded wire. Therefore, the present invention aims to provide an aluminum extruded wire made of aluminum with a small amount of alloying elements added, which has high strength and high strength uniformity in the longitudinal direction. [Means for solving the problem]

[0009] One aspect of the present invention is: Fe, Cu, Ti, Mn, Mg, Cr, B, Ga, V, and Zn with a total content of 0.01% by mass or less, It includes one or more elements selected from the group consisting of Ni, Y, and Si, The remainder consists of Al and inevitable impurities, In a cross-section perpendicular to the longitudinal direction of the extrusion line, the average crystal grain size measured by backscattered electron diffraction is 15 to 50 μm in both the central measurement region including the center point of the cross-section and the peripheral measurement region in contact with the outer periphery of the cross-section, and it is an aluminum extrusion line.

[0010] Aspect 2 of the present invention is The aluminum extrusion line according to Aspect 1, which satisfies the following formula (1). |Dp - Dc| ≤ 20 (μm) ··· (1) Here, Dc is the average crystal grain size (μm) in the central measurement region of the cross-section, Dp is the average crystal grain size (μm) in the peripheral measurement region of the cross-section.

[0011] Aspect 3 of the present invention is The above center The aluminum extrusion line according to Aspect 1 or 2, wherein the area ratio of the region where the local orientation difference within the crystal grains is 0.2° or more is 15 to 30% in both the measurement region and the peripheral measurement region.

[0012] Aspect 4 of the present invention is The aluminum extrusion line according to any one of Aspects 1 to 3, which satisfies the following formula (2). [[ID=3e]] |Rc - Rp| ≤ 5 (%) ··· (2) Here, Rc is the area ratio (%) of the region where the local orientation difference is 0.2° or more in the central measurement region of the cross-section, Rp is the area ratio (%) of the region where the local orientation difference is 0.2° or more in the peripheral measurement region of the cross-section.

[0013] Aspect 5 of the present invention is When measuring the local orientation difference within the crystal grains in the cross-section by means of backscattered electron diffraction, it is the aluminum extrusion wire according to any one of Aspects 1 to 4 that satisfies the following formula (3). |STD1 - STD2| ≤ 0.02 ··· (3) Here,[[]]END]] STD1 is the standard deviation of the measured value (°) of the local orientation difference in the central measurement region of the cross-section, STD2 is the standard deviation of the measured value (°) of the local orientation difference in the peripheral measurement region of the cross-section.

[0014] Aspect 6 of the present invention is the aluminum extrusion wire according to any one of Aspects 1 to 5, wherein the total content of one or more selected from the group consisting of Ni, Y, and Si is 10 to 2000 mass ppm.

[0015] Aspect 7 of the present invention is the aluminum extrusion wire according to any one of Aspects 1 to 6, having a diameter of 1 to 10 mm.

[0016] Aspect 8 of the present invention is the aluminum extrusion wire according to any one of Aspects 1 to 7, which is for aluminum wiring of semiconductor elements.

[0017] Aspect 9 of the present invention is the aluminum extrusion wire according to any one of Aspects 1 to 8, which is for a superconducting stabilizer used at 20 K or lower.

Advantages of the Invention

[0018] According to one embodiment of the present invention, there can be provided an aluminum extrusion wire made of aluminum with a small addition amount of alloy elements, which has high strength and high strength uniformity in the longitudinal direction.

Brief Description of the Drawings

[0019] [Figure 1A]This is an EBSD-KAM map measured in the central measurement area of ​​a cross-section perpendicular to the longitudinal direction of the Al extrusion line. [Figure 1B] This is an EBSD-KAM map measured in the peripheral measurement area of ​​a cross-section perpendicular to the longitudinal direction of the Al extrusion line. [Modes for carrying out the invention]

[0020] The inventors of this invention have diligently researched the fact that aluminum extruded wires with a low amount of alloying elements tend to have low strength and are prone to strength variations (strength non-uniformity) along the length of the extruded wire. As a result, they found that in such aluminum extruded wires, precipitation strengthening and solid solution strengthening are less likely to occur due to the low amount of alloying elements, and that grain size is the dominant factor in the strength of the aluminum extruded wire. Based on this finding, further investigations revealed that by controlling both the grain size in the central measurement area and the grain size in the peripheral measurement area in a cross section perpendicular to the longitudinal direction of the aluminum extruded wire to an appropriate range, the strength of the aluminum extruded wire can be appropriately controlled, resulting in the suppression of strength variations along the length and improvement of strength uniformity along the length, thus completing the present invention.

[0021] In the case of extruded aluminum (AA1100 series) and aluminum alloys, the extrusion process involves common strengthening mechanisms such as precipitation, grain boundary strengthening, and work hardening, resulting in high strength. Therefore, the influence of strength changes due to grain size is small. Consequently, based on conventional knowledge, grain size is not considered when examining the strength uniformity along the length of the extruded wire.

[0022] The following describes an aluminum extruded wire according to an embodiment of the present invention.

[0023] [Aluminum extruded wire] 1.Chemical composition The chemical composition of the aluminum extruded wire (hereinafter sometimes simply referred to as "extruded wire") according to the embodiment is: Fe, Cu, Ti, Mn, Mg, Cr, B, Ga, V, and Zn with a total content of 0.01% by mass or less, It includes one or more elements selected from the group consisting of Ni, Y, and Si, The remainder consists of Al and unavoidable impurities. Unavoidable impurities refer to trace impurities contained in the aluminum raw material (primary metal, etc.).

[0024] In the extruded wire according to this embodiment, specific elements are intentionally added to high-purity aluminum. The intentionally added components (sometimes referred to as "intentionally added components" or simply "added components") are Ni, Y, and Si. These elements are fine precipitation strengthening elements. Excluding the intentionally added components, the chemical composition contains Fe, Cu, Ti, Mn, Mg, Cr, B, Ga, V, and Zn in a total content of 0.01% by mass or less, with the remainder being Al and unavoidable impurities. In other words, excluding the intentionally added components, it is high-purity aluminum of 4N (99.99% by mass) or higher.

[0025] The total content of one or more intentionally added components selected from the group consisting of Ni, Y, and Si is preferably 10 to 2000 ppm by mass, and more preferably 30 to 300 ppm by mass. Each intentionally added component is preferably contained within the following ranges in order to exert the effect of strengthening fine precipitation. When Ni is included as an intentionally added component, the Ni content can be 10 to 1000 ppm by weight, preferably 30 to 300 ppm by weight, and particularly preferably 30 to 100 ppm by weight. When Y is included as an intentionally added component, the Y content can be 10 to 2000 ppm by weight, 30 to 1000 ppm by weight, and is particularly preferably 50 to 300 ppm by weight. When Si is included as an intentionally added component, the Si content can be 10 to 100 ppm by weight.

[0026] In this specification, a material obtained by adding a predetermined intentional additive to high-purity aluminum (4N or higher) may be referred to as a "high-purity aluminum-based material."

[0027] 2.Crystal structure The aluminum extruded wire according to this embodiment has the following crystalline structure.

[0028] (crystal grain size) In the aluminum extruded wire according to the embodiment, the average grain size measured by backscatter electron diffraction (EBSD) in both a central measurement region including the center point of the cross-section and a peripheral measurement region tangent to the outer circumference of the cross-section, in a cross-section perpendicular to the longitudinal direction, is 15 to 50 μm. The preferred range for the average grain size is 27.5 to 50 μm, the more preferred range is 28 to 46 μm, and the particularly preferred range is 29 to 40 μm. The inventors have discovered for the first time that an extruded wire with such a crystal grain size, which is an aluminum extruded wire made of aluminum with a small amount of alloying elements added, has high strength uniformity in the longitudinal direction. The reason for these effects is not entirely clear, but it is presumed that the grain boundary strengthening mechanism in high-purity aluminum-based materials has an optimal grain size range. If the grain size is larger than the optimal range, grain boundary strengthening becomes insufficient, and if the grain size is smaller than the optimal range, recrystallization easily occurs during processing, causing the grain size to locally increase, and the grain boundary strengthening mechanism does not function properly.

[0029] The center point of a cross-section perpendicular to its longitudinal direction is the center of the circle if the perimeter of the cross-section is circular, or the intersection of the major and minor axes if it is elliptical. In the case of a polygon, the center point of the cross-section is the intersection of multiple diagonals if they intersect at a single point, or the center of the circumcircle of the polygon if the multiple diagonals do not intersect at a single point.

[0030] Preferably, the central measuring area is positioned such that the intersection of its diagonals coincides with the center point of the cross-section. The central measuring area is, for example, a rectangular area of ​​0.46 mm × 0.61 mm. However, if the diameter of the aluminum extruded wire is small, the dimensions of the central measuring area may be reduced. If the diameter of the aluminum extruded wire is 1.6 mm or less, the central measuring area may be a rectangular area of ​​0.23 mm × 0.31 mm, and if it is greater than 1.6 mm, it may be a rectangular area of ​​0.46 mm × 0.61 mm.

[0031] The peripheral measurement area is preferably positioned so that both ends of one of the two opposing long sides of the peripheral measurement area are in contact with the outer circumference of the cross-section. The peripheral measurement area is, for example, a rectangular area of ​​0.46 mm × 0.61 mm. However, if the diameter of the aluminum extruded wire is small, the dimensions of the peripheral measurement area may be reduced. If the diameter of the aluminum extruded wire is 1.6 mm or less, the peripheral measurement area is a rectangular area of ​​0.23 mm × 0.31 mm, and if it is greater than 1.6 mm, it may be a rectangular area of ​​0.46 mm × 0.61 mm.

[0032] If the outer circumference of the cross-section is rounded, the outer circumference shape may be defined excluding the rounded portion. The presence or absence of blurring is determined by scanning electron microscopy (SEM) observation, as described later, if the focus within the peripheral measurement area is not uniform, then blurring is considered to be present.

[0033] Cross-sectional measurements using the EBSD method are performed as follows. EBSD (Earth-borne Spectroscopy) is a widely used method for analyzing the orientation distribution of crystal textures. Typically, EBSD is performed using a scanning electron microscope (SEM) equipped with a backscatter electron diffraction detector. For example, the Symmetry detector manufactured by Oxford Instruments Ltd. can be used as a backscatter electron diffraction detector.

[0034] A sample of a predetermined length (e.g., 25 mm in length) is cut from the extruded wire at a cross-section perpendicular to the longitudinal direction of the extruded wire. The cut sample is embedded in resin, and the cross-section is polished and etched. Then, an electron beam is scanned across the cross-section, and the diffraction pattern of backscattered electrons is read by the instrument.

[0035] Specifically, the diffraction pattern of backscattered electrons loaded into the instrument is first imported into a computer, and the sample surface is scanned while performing crystal orientation analysis using analysis software. This indexes the crystals at each measurement point, and the crystal orientation at each measurement point is determined. At this time, a continuous region having the same crystal orientation is defined as a single crystal grain, and a mapping image of the crystal grain distribution, i.e., a grain map, is obtained. In defining a single crystal grain, adjacent crystals are considered to have the same crystal orientation if the angle difference between their crystal orientations is 10° or less. This allows images of the crystal grains to be recorded in a computer based on the crystal orientation calculated at each measurement point.

[0036] Further image processing is performed to obtain the measured equivalent diameter of the crystal grain size. The average of the equivalent diameters is calculated using area-weighted averaging, and this is defined as the "average crystal grain size."

[0037] The aluminum extruded wire according to the embodiment preferably satisfies the following formula (1). |Dp-Dc|≦20(μm)···(1) Here, Dc is the average grain size (μm) in the central measurement region of the cross-section. Dp is the average crystal grain size (μm) in the peripheral measurement area of ​​the cross-section.

[0038] By controlling the difference (absolute value) between the average grain size Dc in the central measurement area of ​​the cross-section and the average grain size Dp in the peripheral measurement area to be 20 μm or less, the strength in the longitudinal direction of the extruded wire can be made even more uniform. The reason for this effect is not entirely clear, but it is presumed to be due to the following mechanism.

[0039] As mentioned above, in aluminum extruded wire with a small amount of alloying elements, precipitation strengthening and solid solution strengthening can be ignored, and grain size is the dominant factor in the strength of the extruded wire. Furthermore, in aluminum extruded wire with a small amount of alloying elements, the processing temperature has a significant effect. In extrusion molding, the flow velocity of aluminum differs significantly between the central and peripheral portions within a cross-section perpendicular to the longitudinal direction. In aluminum extrusion billets, the peripheral portion in contact with the container is constrained by friction, resulting in a lower aluminum flow velocity in the peripheral portion than in the central portion. This difference in flow velocity leads to the partial formation of shear deformation regions. As a result, in the obtained aluminum extruded wire, the grain size differs significantly between the central and peripheral measurement regions in a cross-section perpendicular to the longitudinal direction. In particular, the difference in grain size is pronounced at the tail of the extruded wire. It is thought that the strength of aluminum extruded wire with a small amount of alloying element addition is greatly affected by grain size, leading to a decrease in strength uniformity along the length of the extruded wire.

[0040] Therefore, by reducing the difference in aluminum flow velocity between the central and peripheral parts from the start to the end of extrusion molding, the difference in grain size between the central and peripheral measurement areas can be reduced, thereby significantly suppressing fluctuations in strength along the length of the extruded wire. In other words, by improving the uniformity of grain size in the cross-section perpendicular to the longitudinal direction of the extruded wire, the uniformity of strength along the length of the extruded wire can be improved. Furthermore, as will be described later, by setting the container temperature of the extrusion molding machine 20 to 80°C lower than the billet temperature during extrusion molding, the difference in aluminum flow velocity between the central and peripheral parts can be reduced.

[0041] (Local orientation difference within a crystal grain) In both the central and peripheral measurement regions, the area ratio of regions with a local orientation difference of 0.2° or more within the crystal grains is preferably 15-30%, more preferably 15-25%, and still preferably 15-20%. By including a moderate amount of high-strain regions, an increase in strength due to work hardening can be expected, and the effect of this strength increase is more easily exerted uniformly along the length of the extruded wire. Therefore, it is possible to obtain an extruded wire with even higher strength and even higher strength uniformity.

[0042] Kernel-Average Misorientation (KAM) is one of the analysis methods used in EBSD (Evidence-Based Spheric Diagram) analysis, measuring the difference in crystal orientation between the measurement point and its vicinity. A larger KAM indicates greater strain within that crystal grain. The area ratio of the region where the local azimuthal error (KAM) is 0.2° or greater (sometimes referred to as the "high local azimuthal error region" or "high strain region") is the area of ​​the measurement range (for example, 0.46 mm × 0.61 mm = 0.28 mm²). 2 This refers to the ratio of the area of ​​the region where the KAM (high strain) is 0.2° or higher (high strain region), when the KAM is set to 100%. A higher area ratio of the high strain region results in a greater work hardening effect.

[0043] A sample prepared using the same procedure as the sample used for cross-sectional measurement by the EBSD method described above was measured using the same apparatus. The measurement step was set to 0.2 μm / pix. The obtained backscattered electron diffraction pattern was analyzed using the analysis software AZtec, and the cumulative frequency of regions with a local azimuth difference of 0.2° or more (high local azimuth difference regions) was calculated and defined as the area of ​​the high-strain region. The area of ​​the high-strain region was defined as the area of ​​the measurement region (e.g., 0.28 mm²). 2 Divide by ) to find the area ratio of the high-strain region. Furthermore, in order to exclude grain boundaries at this time, if the KAM is 10° or greater, it is recognized as a grain boundary and excluded from the above area ratio calculation.

[0044] The extruded wire is further preferably satisfied with the following equation (2). |Rc-Rp|≦5(%)···(2) Here, Rc is the area percentage (%) of the region with a local orientation difference of 0.2° or more in the central measurement area of ​​the cross-section. Rp is the area percentage (%) of the region in the peripheral measurement area of ​​the cross-section where the local orientation difference is 0.2° or more.

[0045] Equation (2) suggests that the area ratio Rc of the region with a local orientation difference of 0.2° or more (high strain region) in the central measurement area of ​​the cross section and the area ratio Rp of the region with a local orientation difference of 0.2° or more (high strain region) in the peripheral measurement area have similar values. As mentioned above, high-strain regions can contribute to increased strength due to work hardening. Therefore, if the area ratio of high-strain regions is relatively uniform within the cross-section, the strength within the cross-section becomes relatively uniform, further improving the strength uniformity throughout the extruded wire.

[0046] Furthermore, as will be described later, by setting the container temperature of the extrusion molding machine 20 to 60°C lower than the billet temperature during extrusion molding, the difference in aluminum flow velocity between the central and peripheral parts can be reduced.

[0047] When the local orientation difference (KAM) within the crystal grains in the cross-section is measured by backscattered electron diffraction, it is preferable that the following equation (3) is satisfied. |STD1-STD2|≦0.02···(3) Here, STD1 is the standard deviation of the measured value (°) of the local orientation difference in the central measurement area of ​​the cross-section. STD2 is the standard deviation of the measured value (°) of the local orientation difference in the peripheral measurement area of ​​the cross-section.

[0048] When the distribution of local orientation difference (KAM) in the central and peripheral measurement regions of a cross-section is uniform, the standard deviation of each KAM becomes small, and the difference (absolute value) between their standard deviations also becomes small. In other words, by satisfying equation (3), the variability of KAM in the central and peripheral measurement regions of the cross-section becomes small. Because the area ratio of high-strain regions is relatively uniform within the cross-section, the strength within the cross-section becomes relatively uniform, and the strength uniformity of the entire extruded wire can be further improved.

[0049] Furthermore, as will be described later, by setting the container temperature of the extrusion molding machine 20 to 60°C lower than the billet temperature during extrusion molding, the difference in aluminum flow velocity between the central and peripheral parts can be reduced.

[0050] Aluminum extruded wire can be made into any size and shape depending on the application; for example, its diameter may be between 1 and 10 mm.

[0051] The aluminum extruded wire according to this embodiment is made of a high-purity aluminum-based material and is therefore suitable for use in aluminum wiring for semiconductor devices, superconducting stabilizing materials used at temperatures below 20K, and the like. Furthermore, it is preferable to control the type and amount of intentionally added components to the aluminum extruded wire according to the application.

[0052] (Manufacturing method for aluminum extruded wire) A method for manufacturing aluminum extruded wire according to the embodiment is described. However, a person skilled in the art who has access to the disclosure of this application may arrive at a different method for manufacturing aluminum extruded wire according to the embodiment based on the description therein.

[0053] High-purity aluminum (for example, Al with a purity of 99.99% (4N) or higher) is used as a raw material, to which a predetermined amount of intentionally added components (one or more of Ni, Y, and Si) are added, and the mixture is stirred, dissolved, and held. Subsequently, a billet is cast according to a standard method, and further processing is performed to create an extrusion billet of the desired dimensions.

[0054] The extrusion billet is heated to the billet preheating temperature (referred to as the "billet temperature"), and then extruded using an extrusion apparatus. The billet temperature should be within the range of billet temperatures commonly used in extrusion molding.

[0055] During extrusion molding, the heating temperature of the extruder's container (referred to as the "container temperature") is set 20 to 80°C lower than the billet temperature. In other words, the billet temperature BL and the container temperature C are set so that (billet temperature BL - container temperature C) is between 20 and 80°C. This makes it possible to set the average grain size of the central and peripheral measurement areas of the cross-section perpendicular to the longitudinal direction of the extruded line to 15 to 50 μm, and to keep the difference between the average grain size Dc of the central measurement area and the average grain size Dp of the peripheral measurement area to 20 μm or less.

[0056] Furthermore, by setting the (billet temperature BL - container temperature C) to 20-60°C, the area ratio of the high-strain region in the central and peripheral measurement areas of the cross-section can be set to 15-30%, and the difference ΔR between the area ratio Rc of the high-strain region in the central measurement area and the area ratio Rp of the high-strain region in the peripheral measurement area can be reduced to 5% or less. In addition, the difference in the standard deviation of the local orientation difference (KAM) in the central and peripheral measurement areas of the cross-section can be reduced to 0.02 or less. A more preferable range for (billet temperature BL - container temperature C) is 25-45°C, and an even more preferable range is 30-40°C.

[0057] Conventionally, in order to maintain the billet temperature, the container temperature was kept at approximately the same level as the billet temperature (usually within a temperature difference of 10°C). However, in the aluminum extruded wire according to this embodiment, the container temperature is set 20°C to 80°C lower than the billet temperature, thereby generating appropriate strain within the crystal grains of the resulting extruded wire. This makes it possible to obtain an extruded wire with a desired crystal grain size. [Examples]

[0058] A sample of aluminum extruded wire for measurement was prepared using the following procedure.

[0059] (1) Preparation of samples for measurement High-purity aluminum (99.999% purity Al) obtained by a three-phase electrolysis method was used as the Al raw material. High-purity aluminum raw material was placed in a graphite crucible, Ni was added as an intentional additive, and after stirring and degassing (vacuum held at 700°C for 2 hours), a billet was cast at 740°C using a graphite mold with an inner diameter of 100 mm (inner diameter 100 mm x inner height 230 mm).

[0060] The obtained billet was processed to produce an extrusion billet with dimensions of φ70 mm x length 180 mm. Subsequently, the extrusion billet was extruded to obtain an extruded wire with dimensions of φ2 mm x length approximately 50 m. The billet temperature BL and container temperature C during extrusion molding were controlled to satisfy the "difference ΔT between billet temperature BL and container temperature C during extrusion molding (= billet temperature B (°C) - container temperature C (°C))" shown in Table 1, and extruded wires for Examples 1-3 and Comparative Examples 1-4 were produced. The billet temperature BL during extrusion molding was set to 350-390°C, which is a typical billet temperature for extrusion molding of high-purity aluminum materials.

[0061] The content of 12 elements was measured for each extruded wire obtained by solid-state emission spectroscopy. In all samples, the content of Ni was 50 ppm by mass, and the total content of Si, Fe, Cu, Ti, Mn, Mg, Cr, B, Ga, V, and Zn was 18 ppm by mass.

[0062] The first 2m and last 2m (tail) of the extruded wire were removed as transient sections. Then, samples were cut from the extruded end on the start side and the extruded end (tail side). First, a 200mm length of metal wire was cut from each end to create a tensile test specimen (sample) for tensile strength testing, and then a 25mm length of sample for grain size measurement was cut from the extruded end.

[0063] [Table 1]

[0064] (Measurement of crystal grain size) The crystal structure was observed using backscattered electron diffraction (EBSD). A 25 mm long sample was cut from the end of the extrusion process, perpendicular to the longitudinal direction of the extrusion line. The cut sample was embedded in resin, and the cross-section was polished and etched. Then, an electron beam was scanned across the cross-section, and the diffraction pattern of backscattered electrons was read using an instrument. The cross-section of each sample was measured by EBSD using the procedure described in the embodiment, and the average grain size was determined. A scanning electron microscope (JEOL JSM-7900F) was used, and a Symmetry backscatter electron diffraction detector (Oxford Instruments Ltd.) was used.

[0065] Table 2 shows the average grain size in the central and peripheral measurement areas of the cross-section for each of Examples 1-3 and Comparative Examples 1-4. Furthermore, we evaluated whether the average grain size met the requirements of the embodiment (average grain size of 15-50 μm), and indicated "○" if it met and "×" if it did not. Furthermore, the difference (absolute value) ΔD between the average crystal grain size Dc in the central measurement area and the average crystal grain size Dp in the surrounding measurement area was calculated and is shown in Table 2. In addition, it was evaluated whether ΔD satisfies the preferred range of the embodiment (ΔD ≤ 20 μm), and it was indicated as "○" if it satisfies and "×" if it does not.

[0066] (Measurement of local orientation difference within crystal grains) Following the procedure described in the embodiment, the local orientation difference (KAM) within the crystal grains in the cross-section of each sample was measured, and the area ratio of regions with a KAM of 0.2° or more (high strain regions) was determined. Table 3 shows the area ratio of the high-strain region in the central and peripheral measurement areas of the cross-section for each of Examples 1-3 and Comparative Examples 1-4. Furthermore, we evaluated whether the area ratio of the high-strain region met the preferred range of the embodiment (15-30% high-strain area), and indicated "○" if it met and "×" if it did not. Furthermore, the difference (absolute value) ΔR between the high-strain region Rc in the central measurement area and the high-strain region Rp in the peripheral measurement area was calculated and is shown in Table 3. In addition, it was evaluated whether ΔR satisfies the preferred range of the embodiment (ΔR ≤ 5%), and it was indicated as "○" if it satisfies and "×" if it does not.

[0067] The mean, standard deviation, and mode of KAM were determined from the measured values ​​of KAM within the crystal grains in the cross-section of each sample. Table 4 shows the mean, standard deviation, and mode of KAM in the central and peripheral measurement areas of the cross-section for each of Examples 1-3 and Comparative Examples 1-4. Furthermore, the difference (absolute value) ΔSTD between the standard deviation STD1 of the central measurement area and the standard deviation STD2 of the peripheral measurement area was calculated and is shown in Table 4. In addition, it was evaluated whether ΔSTD satisfies the preferred range of the embodiment (ΔSTD ≤ 0.02), and it was indicated as "○" if it satisfies and "×" if it does not.

[0068] (Evaluation of tensile strength) Metal wires 200 mm in length were cut from both the extrusion start end and the extrusion end (tail end) of the extrusion wire. The cut metal wires were processed to obtain tensile test specimens (samples). The shape and dimensions of the tensile test specimens were the same as those of JIS Z 2241:2011 No. 4 test specimen.

[0069] The tensile test was conducted in accordance with JIS Z 2241:2011. The tensile test specimen was gripped at both ends (50 mm) with a chuck, and the tensile strength was measured at a tensile speed of 20 mm / min. The tensile test method was also carried out in accordance with JIS Z 2241:2011.

[0070] Table 5 shows the tensile strength TS1 of the sample at the start of extrusion and the tensile strength TS2 of the sample at the end of extrusion (tail end) for each of Examples 1-3 and Comparative Examples 1-4. Furthermore, samples were classified as A if TS2 was 53.5 MPa or higher, B if TS2 was 52 MPa or higher but less than 53.5 MPa, and C if TS2 was less than 52 MPa.

[0071] Furthermore, the difference ΔTS(TS1-TS2) between the tensile strength TS1 of the sample at the start of extrusion and the tensile strength TS2 of the sample at the end of extrusion (tail end) was calculated and is shown in Table 5. Cases where ΔTS was 5 MPa or less were classified as A, cases where it was 10 MPa or more but less than 5 MPa as B, and cases where it was greater than 10 MPa as C.

[0072] An overall evaluation of each sample was performed based on the evaluation results of TS2 and ΔTS. If at least one evaluation was C, the overall evaluation was C; if both evaluations were A, the overall evaluation was A; otherwise, the overall evaluation was B.

[0073] [Table 2]

[0074] [Table 3]

[0075] [Table 4]

[0076] [Table 5]

[0077] In Examples 1-3, the difference between the billet temperature BL and the container temperature C during extrusion molding (= billet temperature BL - container temperature C) was 20-80°C. As a result, the average grain size Dc and Dp in the central and peripheral measurement areas of the cross-section of the extruded wire were both 15-50 μm, and the difference ΔD between the average grain size Dc and Dp was 20 μm or less (Table 2). Therefore, the tensile strength of the extruded wire was high at the end of the extrusion (tail), and the difference in tensile strength between the beginning and end of the extrusion (tail) was small. In other words, the extruded wires of Examples 1-3 not only had high strength, but also less variation in strength along the length direction, resulting in high strength uniformity.

[0078] In particular, in Examples 1 and 2, the difference between the billet temperature BL and the container temperature C was 20 to 60°C, centerIn the measurement area and the surrounding measurement area, the area fractions Rc and Rp of regions where the local orientation difference within the crystal grains was 0.2° or more were both 15-30%, and the difference ΔR between the area fractions Rc and Rp was 5% or less. Furthermore, the difference ΔSTD between the standard deviations STD1 and STD2 of the measured values ​​(°) of the local orientation difference between the central measurement area and the surrounding measurement area was 0.02 or less. As a result, the tensile strength of the extruded wire at the end of the extrusion (tail) and the strength uniformity along the length of the extruded wire were both particularly high.

[0079] In Comparative Example 1, the difference between the billet temperature BL and the container temperature C was -20°C, with the container temperature being higher than the billet temperature. As a result, the average grain size in the surrounding measurement area exceeded 50 μm. Consequently, the tensile strength of the extruded wire was low at the end of the extrusion (tail), and the difference in tensile strength between the beginning and end of the extrusion (tail) was large.

[0080] In Comparative Example 2, the difference between the billet temperature BL and the container temperature C was 0°C. As a result, the average grain size in the peripheral measurement area exceeded 50 μm, and the difference between the average grain size in the central measurement area and the peripheral measurement area exceeded 20 μm. Consequently, the tensile strength of the extruded wire was low at the end of the extrusion (tail), and the difference in tensile strength between the beginning and end of the extrusion (tail) was large.

[0081] In Comparative Example 3, the difference between the billet temperature BL and the container temperature C was 100°C, indicating a large temperature difference. As a result, the average grain size in the central measurement area was less than 15 μm. Consequently, the tensile strength of the extruded wire at the end of the extrusion (tail) was low.

[0082] Similar to Comparative Example 3, Comparative Example 4 had a large temperature difference of 90°C between the billet temperature BL and the container temperature C. As a result, the average grain size in the central measurement area was less than 15 μm. Consequently, the tensile strength of the extruded wire at the end of the extrusion (tail) was low.

Claims

1. Fe, Cu, Ti, Mn, Mg, Cr, B, Ga, V, and Zn with a total content of 0.01% by mass or less, It contains 10 to 2000 ppm by mass of Ni, The remainder consists of Al and unavoidable impurities. In a cross-section perpendicular to the longitudinal direction of the extruded line, the average grain size measured by backscattered electron diffraction in both the central measurement region including the center point of the cross-section and the peripheral measurement region tangent to the outer periphery of the cross-section is 15 to 50 μm, respectively. The central measuring area is positioned such that the intersection of its diagonals coincides with the center point of the cross-section. When the diameter of the aluminum extruded wire is 1.6 mm or less, the central measuring area is a rectangular area of ​​0.23 mm × 0.31 mm. When the diameter is greater than 1.6 mm, the central measuring area is a rectangular area of ​​0.46 mm × 0.61 mm. The peripheral measuring area is positioned such that both ends of one of the two opposing long sides of the peripheral measuring area are in contact with the outer circumference of the cross-section, and when the diameter of the aluminum extruded wire is 1.6 mm or less, the peripheral measuring area is a rectangular area of ​​0.23 mm × 0.31 mm, and when the diameter is greater than 1.6 mm, the central measuring area is a rectangular area of ​​0.46 mm × 0.61 mm, wherein the aluminum extruded wire.

2. An aluminum extruded wire according to claim 1, satisfying the following formula (1). |Dp-Dc|≦20(μm)...(1) Here, Dc is the average grain size (μm) in the central measurement region of the cross-section. Dp is the average crystal grain size (μm) in the peripheral measurement area of ​​the cross-section.

3. The aluminum extruded wire according to claim 1 or 2, wherein in both the central measurement region and the peripheral measurement region, the area ratio of regions where the local orientation difference within the crystal grains is 0.2° or more is 15 to 30%.

4. An aluminum extruded wire according to any one of claims 1 to 3, satisfying the following formula (2). |Rc-Rp|≦5(%)...(2) Here, Rc is the area percentage (%) of the region in the central measurement area of ​​the cross-section where the local orientation difference is 0.2° or more. Rp is the area percentage (%) of the region in the peripheral measurement area of ​​the cross-section where the local orientation difference is 0.2° or more.

5. An aluminum extruded wire according to any one of claims 1 to 4, wherein when the local orientation difference within the crystal grains in the cross-section is measured by backscattered electron diffraction, the following equation (3) is satisfied. |STD1-STD2|≦0.02...(3) Here, STD1 is the standard deviation of the measured value (°) of the local orientation difference in the central measurement area of ​​the cross-section, STD2 is the standard deviation of the measured value (°) of the local orientation difference in the peripheral measurement area of ​​the cross-section.

6. An aluminum extruded wire according to any one of claims 1 to 5, having a diameter of 1 to 10 mm.

7. An aluminum extruded wire according to any one of claims 1 to 6, for use in aluminum wiring of semiconductor devices.

8. An aluminum extruded wire according to any one of claims 1 to 7, for use as a superconducting stabilizer for use at 20K or below.

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