WO2020137394A1

WO2020137394A1 - Aluminum alloy foil and method for producing aluminum alloy foil

Info

Publication number: WO2020137394A1
Application number: PCT/JP2019/047367
Authority: WO
Inventors: 貴史鈴木
Original assignee: 三菱アルミニウム株式会社
Priority date: 2018-12-26
Filing date: 2019-12-04
Publication date: 2020-07-02
Also published as: KR20210060589A; JPWO2020137394A1; JP6754025B1; CN112867806B; JP2021075778A; KR102501356B1; CN112867806A

Abstract

This aluminum alloy foil includes a composition containing Fe (1.0-1.8 mass%), Si (0.09-0.20 mass%), Cu (0.005-0.05 mass%), and Mn (limited to no more than 0.01 mass%), the balance being Al and unavoidable impurities. According to a crystal orientation analysis per unit area by electron backscatter diffraction (EBSD), the length ratio of high angle grain boundaries (HAGBs) having an orientation difference of at least 15° to low angle grain boundaries (LAGBs) having an orientation difference of at least 2° but less than 15° satisfies "HAGBs/LAGBs > 2.0". As a texture, the orientation density of Cu is not more than 40, and the orientation density of R is not more than 30.

Description

Aluminum alloy foil and method for manufacturing aluminum alloy foil

The present invention relates to an aluminum alloy foil having excellent formability and a method for manufacturing the aluminum alloy foil.

The aluminum foil used as packaging material for batteries such as foods and lithium-ion secondary batteries is subject to great deformation due to press molding. Therefore, good formability has been conventionally demanded, and soft foils of 1000 series alloys such as 1N30 and 8000 series alloys such as 8079 and 8021 are used. Elongation is an important parameter for forming, but it does not deform aluminum alloy foil in one direction and so-called bulging is often performed. On the other hand, it is required that not only the parallel direction but also the expansion in each direction such as 45° and 90° be high. In addition, recently, the thickness of the packaging material has been reduced in the field of battery packaging materials.

For example, in Patent Document 1, when the average crystal grain size is 20 μm or less and the number density of the intermetallic compound having a circle equivalent diameter of 1.0 to 5.0 μm is set to a predetermined amount or more, the intermetallic compound is recrystallized. To function as a nucleation site for the crystal grain size after final annealing.
In Patent Document 2, a boundary having an orientation difference of 5° or more in a crystal orientation analysis by electron backscattering analysis image method (EBSP) is defined as a crystal grain boundary, and a crystal grain included in the crystal grain boundary is defined as a crystal grain boundary. An aluminum alloy foil has been proposed in which the average value D is 12 μm or less and the area ratio of crystal grains having a crystal grain size of 20 μm or more is 30% or less.
In Patent Document 3, the average crystal grain size and the average grain size of the subgrains are specified to be not more than a predetermined value, and the dispersion density of the Al—Fe compound is specified to be not less than a predetermined value.
In Patent Document 4, the formability is improved by defining the texture (orientation density).

International Publication No. 2014/021170 International Publication No. 2014/034240 JP-A-2004-27353 International Publication No. 2013/168606

However, in Patent Document 1, although the number density of coarse intermetallic compounds having an equivalent circle diameter of 1.0 to 5.0 μm is specified, the maximum amount of Cu added is 0.5 mass%. Cu is an element that reduces the rollability even in a small amount, and the risk of fracture due to the generation of edge cracks during rolling increases. Further, when the foil becomes thin, it may be difficult to maintain high moldability.
Although Patent Document 2 defines a very fine crystal grain size, it is limited to a grain boundary having an orientation difference of 5° or more. When the angle is 5° or more, it is not clear whether the large-angle grain boundaries and the small-angle grain boundaries are mixed and the crystal grains surrounded by the large-angle grain boundaries are fine.
Unlike Patent Documents 1 and 2, Patent Document 3 is a patent relating to a thin foil having a thickness of 10 μm or less, not a battery exterior foil. Since it is manufactured without intermediate annealing, a texture develops and stable elongation cannot be obtained in the 0°, 45° and 90° directions. If the foil is thin, high moldability cannot be expected.
In Patent Document 4, the texture is controlled, but the elongation characteristics are not sufficient and the balance between strength and elongation is not sufficient.

The present invention has been made in view of the above problems, and an object thereof is to provide an aluminum alloy foil having good workability and high elongation properties.

In the aluminum alloy foil of the present invention, the first embodiment is Fe: 1.0 mass% or more and 1.8 mass% or less, Si: 0.09 mass% or more and 0.20 mass% or less, Cu: 0.005. The content of Mn is controlled to 0.01% by mass or less, and the balance is composed of Al and unavoidable impurities, and the content per unit area by backscattering electron diffraction (EBSD) is In the crystal orientation analysis, the ratio "HAGBs/LAGBs>2.0" of the length of the high-angle grain boundaries (HAGBs) having an orientation difference of 15° or more and the small-angle grain boundaries (LAGBs) having an orientation difference of 2° or more and less than 15° is used. The texture is characterized by having a Cu orientation density of 40 or less and an R orientation density of 30 or less.

The invention of an aluminum alloy foil in another form is characterized in that, in the above-mentioned form of the invention, Si: more than 0.10 mass% and 0.20 mass% or less.

The invention of an aluminum alloy foil in another mode is characterized in that, in the invention of the above mode, the elongation in each direction of 0°, 45° and 90° with respect to the rolling direction is 20% or more.

The invention of an aluminum alloy foil of another aspect is the same as the invention of the aspect described above, in which the crystal grains surrounded by a large-angle grain boundary having an orientation difference of 15° or more have an average grain size of 10 μm or less and a maximum grain size/average grain size. It is characterized in that ≦3.0.

The method for producing an aluminum alloy foil according to the present invention is the method for producing an aluminum alloy foil of each of the above-mentioned forms, which is a homogenization treatment in which the ingot of the aluminum alloy having the above-mentioned composition is held at 520 to 560° C. for 6 hours or more. After the homogenization treatment, hot rolling is performed so that the rolling finish temperature is 230° C. or higher and lower than 280° C., intermediate annealing is performed at 300 to 400° C. during the cold rolling, and then the final cold rolling rate. Is 90% or more, and the final annealing is performed at 250 to 350° C. for 10 hours or more.

The contents specified in the present invention will be described below.
-Fe: 1.0% by mass or more and 1.8% by mass or less Fe crystallizes as an Al-Fe intermetallic compound during casting, and when the size is large, it becomes a site of recrystallization during annealing and fine recrystallized grains are formed. Has the effect of If it is less than 1.0% by mass, the distribution density of the coarse intermetallic compound is low, the effect of refining it is low, and the final crystal grain size distribution is also nonuniform. If it exceeds 1.8% by mass, the effect of refining the crystal grains is saturated or reduced, and the size of the Al-Fe compound produced during casting becomes very large, resulting in a decrease in foil elongation and rollability. A particularly preferred range is 1.0% by mass or more and 1.6% by mass or less.

-Si: 0.09% by mass or more and 0.20% by mass or less Si forms an intermetallic compound together with Fe, but if added in excess, it causes coarsening of the size of the compound and reduction of the distribution density. If the content exceeds the upper limit, there is a concern that elongation and formability due to coarse crystallized substances may decrease, and further, the uniformity of recrystallized grain size distribution after final annealing may decrease. Further, since Si has an effect of promoting precipitation of Fe, if Si is regulated too much, the amount of solid solution of Fe increases and recrystallization during annealing is strongly suppressed, and in-situ recrystallization often occurs. When in-situ recrystallization occurs during the final annealing, the proportion of small-angle grain boundaries in the total grain boundaries of the recrystallized grain structure increases, leading to a decrease in “HAGBs/LAGBs”, and the density of Cu and R orientations. Will also increase. For these reasons, the Si content is set to 0.09 mass% or more and 0.20 mass% or less. For the same reason, it is preferable that the lower limit of the Si content is more than 0.10 mass% and the upper limit is 0.18 mass%, and the lower limit of the Si content is 0.12 mass%. desirable.

-Cu: 0.005 mass% or more and 0.05 mass% or less Cu is an element that increases the strength of the aluminum foil and reduces the elongation. On the other hand, it has an effect of suppressing excessive work softening during cold rolling, which has been reported for Al-Fe alloys. If it is less than 0.005%, the effect of suppressing work softening is low, and if it exceeds 0.05%, the elongation clearly decreases. It is preferably 0.005% or more and 0.01% or less.

-Mn: 0.01 mass% or less Mn has a function of forming a solid solution in the aluminum matrix or forming a very fine compound and suppressing recrystallization of aluminum. If it is a small amount, it can be expected to suppress work softening like Cu, but if the addition amount is large, recrystallization during intermediate annealing and final annealing will be delayed, and it will be difficult to obtain fine and uniform crystal grains. Therefore, it is regulated to 0.01% or less. It is more preferably 0.005% or less.

・"HAGBs/LAGBs>2.0"
Although not limited to the Al—Fe alloy, depending on the recrystallization behavior during annealing, the length L1 of the high-angle grain boundaries (HAGBs) and the length L2 of the low-angle grain boundaries (LAGBs) occupying the total grain boundaries may be changed. The ratio changes. When the ratio of LAGBs is high after the final annealing, even if the average crystal grains are fine, if L1/L2≦2.0, local deformation is likely to occur and the elongation decreases. For this reason, it is desirable that L1/L2>2.0. By satisfying this requirement, higher elongation can be expected. More preferably, the ratio is 2.5 or more. The lengths of the high-angle grain boundaries and the low-angle grain boundaries can be measured by SEM-EBSD in the same manner as the crystal grain size. L1/L2 is calculated from the total length of the high-angle grain boundaries and the low-angle grain boundaries in the area of the observed visual field.
The above ratio can be adjusted by the heating temperature at the time of annealing, the cold rolling rate, the conditions for homogenization treatment, and the like.

-Cu orientation density of 40 or less and R orientation density of 30 or less as a texture The texture has a great influence on the elongation of the foil. When the Cu orientation density exceeds 40 and the R orientation density also exceeds 30, anisotropy occurs in the elongation values at 0°, 45° and 90°, and particularly the elongation values in the 0° and 90° directions decrease. I will end up. If the elongation is anisotropic, uniform deformation cannot be performed at the time of molding, resulting in deterioration of moldability. More preferably, the Cu orientation density is 30 or less and the R orientation density is 20 or less.
The orientation density can be adjusted by the heating temperature during annealing, the cold rolling rate, the homogenization treatment conditions, and the Fe and Si contents.

・Elongation in each direction of 0°, 45°, 90° relative to the rolling direction is 20% or more. Elongation of the foil is also important for high formability. Especially, the direction parallel to the rolling direction is 0°, and 0° , 45°, and 90° which is the normal to the rolling direction, it is desirable that the elongation is high. Although the elongation value of the foil is greatly influenced by the thickness of the foil, for example, when the thickness is 40 μm and the elongation is 20% or more, high formability can be expected.

The average grain size of the crystal grains surrounded by the high-angle grain boundaries having the orientation difference of 15° or more is 10 μm or less, and the maximum grain size/the average grain size≦3.0.
Since the crystal grain of the soft aluminum foil becomes fine, it is possible to suppress the surface roughness of the foil when it is deformed, and it is expected that high elongation and high formability associated therewith can be expected. The influence of the crystal grain size increases as the foil thickness decreases. In order to realize high elongation properties and high formability associated therewith, it is desirable that the average grain size of the crystal grains surrounded by the large-angle grain boundaries with an orientation difference of 15° or more is 10 μm or less. However, even if the average crystal grain size is the same, if the grain size distribution of the crystal grains is non-uniform, local deformation is likely to occur and elongation is reduced. Therefore, not only the average crystal grain size of 10 μm or less, but also the maximum grain size/average grain size≦3.0, high elongation characteristics can be obtained.
The average particle size is preferably 8 μm or less, and the ratio is preferably 2.0 or less.
It is possible to obtain a high-angle grain boundary map with a misorientation of 15° or more by crystal orientation analysis per unit area by backscattering electron diffraction (EBSD; Electron BackScatter Diffraction).
The above properties can be adjusted by the content of Fe or Si, the homogenization treatment conditions, the heating temperature during annealing, and the cold rolling rate.

-Homogenization treatment: Hold at 520 to 560°C for 6 hours or longer. The homogenization treatment here aims at eliminating microsegregation in the ingot and adjusting the distribution state of intermetallic compounds, and finally makes it fine. This is a very important process for obtaining a uniform grain structure. In the homogenization treatment, if the temperature is lower than 520° C., it takes a very long time to eliminate the microsegregation in the ingot, which is not desirable, and the distribution state of the intermetallic compound is not appropriate. Further, at a temperature higher than 560° C., a crystallized product grows and the density of the coarse intermetallic compound having a grain size of 1 μm or more and less than 3 μm, which serves as a nucleation site for recrystallization, decreases, so that the crystal grain size tends to become coarse. Further, in order to obtain the desired texture at the time of intermediate annealing or final annealing, it is necessary to precipitate Fe as much as possible. At a high temperature exceeding 560°C, a slight amount of re-dissolved Fe occurs. Therefore, 560°C or lower is desirable in order to suppress the amount of solid solution of Fe. The time required for the homogenization treatment varies depending on the temperature, but it is necessary to secure at least 6 hours or more at any temperature. If it is less than 6 hours, there is a concern that the elimination of microsegregation and the precipitation of Fe will be insufficient.

-Finishing temperature of hot rolling: 230°C or higher and lower than 280°C Hot rolling is performed after the homogenization treatment. In the hot rolling, it is desirable that the finishing temperature be less than 280°C to suppress recrystallization. By setting the hot rolling finish temperature to less than 280°C, the hot rolled sheet has a uniform fiber structure. By suppressing the recrystallization after hot rolling in this way, the amount of strain accumulated up to the subsequent thickness of the intermediate annealed sheet increases, and a fine recrystallized grain structure can be obtained during the intermediate annealing. This leads to the fineness of the final crystal grains. At 280°C or higher, recrystallization occurs in a part of the hot-rolled sheet, a fiber structure and a recrystallized grain structure are mixed, and the recrystallized grain size during intermediate annealing becomes non-uniform, which is the final crystal as it is. This leads to uneven particle size. Since the temperature during hot rolling becomes extremely low to finish at less than 230° C., there is a concern that cracks may occur on the side of the plate and productivity may be significantly reduced.

・Intermediate annealing: 300-400℃
The intermediate annealing softens the hardened material by repeating cold rolling to recover the rolling property, promotes precipitation of Fe, and reduces the amount of solid solution Fe. If it is less than 300°C, there is a risk that recrystallization is not completed and the crystal grain structure becomes nonuniform, and if it is higher than 400°C, the recrystallized grains become coarse and the final crystal grain size becomes large. Further, at high temperatures, the amount of Fe deposited decreases and the amount of solid solution Fe increases. When the amount of solid solution Fe is large, recrystallization at the final annealing is suppressed, and the Cu orientation and R orientation density are significantly increased.

-Final cold rolling rate of 90% or more The higher the final cold rolling rate from the intermediate annealing to the final thickness, the larger the amount of strain accumulated in the material and the finer the recrystallized grains after the final annealing. Further, since the crystal grains are refined in the process of cold rolling (grain subdivision), it is desirable that the final cold rolling rate is high in that sense. Specifically, the final cold rolling rate should be 90% or more. Is desirable. If it is less than 90%, the amount of accumulated strain decreases and the grain refinement during rolling becomes insufficient, and the grain size after final annealing also increases. Further, the ratio of in-situ recrystallization also increases, LAGBs having an orientation difference of less than 15° increase, HAGBs/LAGBs decrease, and Cu orientation density and R orientation density also increase. Considering these characteristics, the final cold rolling rate is preferably 98% or more. Although there is no demerit in terms of material properties regarding the upper limit, manufacturing a thin foil by cold rolling exceeding 99.9% leads to a decrease in rollability and an increase in breakage due to side cracks.

Final anneal: Hold at 250° C. to 350° C. for 10 hours or longer Final anneal is performed after final cold rolling to completely soften the foil. If the temperature is less than 250° C. or the holding time is less than 10 hours, the softening may be insufficient, and if the temperature exceeds 350° C., the foil may be deformed or the economy may decrease. The upper limit of the holding time is preferably less than 24 hours from the viewpoint of economy.

According to the present invention, an aluminum alloy foil having high elongation characteristics can be obtained.

It is a figure which shows the planar shape of the square punch used in the limit forming height test in the Example of this invention.

A method for manufacturing an aluminum alloy foil according to an embodiment of the present invention will be described.
Fe: 1.0 mass% or more and 1.8 mass% or less, Si: 0.09 mass% or more and 0.20 mass% or less, Cu: 0.005 mass% or more and 0.05 mass% or less, and Mn: The aluminum alloy ingot was manufactured by controlling the amount to 0.01% by mass or less and adjusting the balance to Al and inevitable impurities. The method for producing the ingot is not particularly limited, and the ingot can be produced by a conventional method such as semi-continuous casting. The obtained ingot is subjected to a homogenizing treatment of holding it at 520 to 560° C. for 6 hours or more.

After the homogenization treatment, hot rolling is performed to set the rolling finish temperature to 230°C or higher and lower than 280°C. After that, cold rolling is performed, and intermediate annealing is performed during the cold rolling. In the intermediate annealing, the temperature is 300°C to 400°C. The intermediate annealing time is preferably 3 hours or more and less than 10 hours. If it is less than 3 hours, the softening of the material may be insufficient when the annealing temperature is low, and long-time annealing of 10 hours or more is economically unfavorable.
The cold rolling of the intermediate annealing corresponds to the final cold rolling, and the final cold rolling rate at that time is 90% or more. The thickness of the foil is not particularly limited, but may be, for example, 10 μm to 40 μm. The final annealing is equivalent to a batch method and is performed at 250 to 350° C. for 10 hours or more.

The obtained aluminum alloy foil has excellent elongation characteristics. For example, when the thickness is 40 μm, the elongation in each direction of 0°, 45°, 90° with respect to the rolling direction is 20% or more. Become.

Further, in the crystal orientation analysis per unit area by backscattering electron diffraction (EBSD), the average grain size of the crystal grains surrounded by the large tilt grain boundaries, which are grain boundaries with a misorientation of 15° or more, is 10 μm or less, and the maximum grain size is 10 μm or less. Diameter/average particle size≦3.0, and the crystal grains are fine. Therefore, it is possible to prevent the surface from being roughened when it is deformed.
Furthermore, in the crystal orientation analysis per unit area by backscattering electron diffraction (EBSD), the grain boundary with a misorientation of 15° or more is defined as a grain boundary with a misorientation of 2° or more and less than 15°, and When the length of the tilt grain boundary is L1 and the length of the small tilt grain boundary is L2, L1/L2>2.0. This has resulted in higher growth.

In addition, in the aluminum alloy foil, it is desirable that the density of the intermetallic compound satisfies the following regulations.
-Density of Al-Fe intermetallic compound having a particle size of 1 μm or more and less than 3 μm: 1×10 ⁴ particles/mm ² or more A particle size of 1 μm or more is generally said to be a nucleation site during recrystallization. Since the intermetallic compound is distributed at a high density, it becomes easy to obtain fine recrystallized grains during annealing. When the particle size is less than 1 μm or the density is less than 1×10 ⁴ particles/mm ² , it is difficult to work effectively as a nucleation site during recrystallization, and when it exceeds 3 μm, pinholes and elongation during rolling tend to be reduced. Become. Therefore, it is desirable that the density of the Al—Fe based intermetallic compound having a particle size of 1 μm or more and less than 3 μm is within the above range.

-Density of Al-Fe-based intermetallic compound having a particle size of 0.1 μm or more and less than 1 μm: 2×10 ⁵ pieces/mm ² or more Generally, it is a size that is said to be unlikely to become a nucleation site during recrystallization, but crystal grains The results are considered to have a great influence on the refinement and recrystallization behavior of Although the overall image of the mechanism is not clear yet, in addition to the coarse intermetallic compounds with a grain size of 1 to 3 μm, fine compounds with a grain size of less than 1 μm are present at high density, resulting in refinement of recrystallized grains after final annealing, and HAGBs. It has been confirmed that the decrease in the length of the /LAGBs is suppressed. There is also a possibility that the separation of the crystal grains during cold rolling (grain subdivision mechanism) is promoted. Therefore, it is desirable that the density of the Al—Fe intermetallic compound having a particle size of 0.1 μm or more and less than 1 μm is within the above range.

The obtained aluminum alloy foil can be deformed by press molding or the like, and can be suitably used as a packaging material for foods or lithium ion batteries. In the present invention, the application of the aluminum alloy foil is not limited to the above, and it can be used for any appropriate application.

An ingot of aluminum alloy having the composition shown in Table 1 was produced by a semi-continuous casting method. Then, for the obtained ingot, according to the manufacturing conditions shown in Table 1 (conditions for homogenization treatment, finish temperature of hot rolling, plate thickness during intermediate annealing, intermediate annealing conditions, final cold rolling rate), After homogenization, hot rolling, cold rolling, intermediate annealing, and cold rolling again (only Comparative Example No. 22 is not subjected to intermediate annealing, only cold rolling), and then a batch of 300° C. for 10 hours Type final annealing was performed to produce an aluminum alloy foil. The thickness of the foil was 40 μm.

The following measurements and evaluations were performed on the obtained aluminum alloy foil.
-Tensile strength and elongation were both measured by a tensile test (foil thickness 40 µm). The tensile test is based on JIS Z2241, and JIS No. 5 test pieces were sampled from a sample so that elongation in each direction of 0°, 45° and 90° with respect to the rolling direction could be measured, and a universal tensile tester (Shimadzu The test was performed with a tensile speed of 2 mm/min using AGS-X 10 kN manufactured by Seisakusho. The calculation of the elongation rate is as follows. First, before the test, two lines are marked on the longitudinal center of the test piece in the vertical direction of the test piece at intervals of 50 mm which is a gauge length. After the test, the broken surfaces of the aluminum alloy foils are brought into contact with each other to measure the distance between marks, and the elongation amount (mm) obtained by subtracting the gauge length (50 mm) from that is divided by the gauge distance (50 mm) to obtain an elongation rate. (%) was calculated.

・Crystal grain size After electropolishing the foil surface, crystal orientation analysis is performed by SEM (Scanning Electron Microscope)-EBSD, and the grain boundaries where the orientation difference between the crystal grains is 15° or more are HAGBs (high tilt grain boundaries). And the size of crystal grains surrounded by HAGBs was measured. The visual field size of 45×90 μm was measured in 3 visual fields at a magnification of 1000, and the average crystal grain size and the maximum grain size/average grain size were calculated. Each crystal grain size was calculated by the equivalent circle diameter, and the EBSD Area method (Average by Area Fraction Method) was used to calculate the average crystal grain size. In addition, OIM Analysis by TSL Solutions was used for the analysis.

・HAGBs/LAGBs
After electropolishing the foil surface, crystal orientation analysis is performed by SEM-EBSD, and high-angle grain boundaries (HAGBs) in which the orientation difference between crystal grains is 15° or more and small inclination angle in which the orientation difference is 2° or more and less than 15° Grain boundaries (LAGBs) were observed. The visual field size of 45×90 μm was measured in 3 visual fields at a magnification of 1000, the lengths of HAGBs and LAGBs in the visual field were determined, and the ratio was calculated.

-Crystal Orientation The Cu orientation is {112}<111> and the R orientation is {123}<634>. For each orientation density, the incomplete pole figure of {111}, {200}, and {220} is measured by the X-ray diffraction method, and the result is used to calculate a three-dimensional orientation distribution function (ODF). And evaluated.

-Limited molding height The molding height was evaluated by a square tube molding test. The test was performed with a universal thin plate forming tester (model 142/20 manufactured by ERICHSEN Co., Ltd.), and an aluminum foil having a thickness of 40 μm was used as a rectangular punch having a shape shown in FIG. Diameter R=4.5 mm). As the test conditions, the wrinkle suppressing force was 10 kN, the punch rising speed (molding speed) was set to 1, and mineral oil was applied as a lubricant to one side of the foil (the side where the punch hits). The punch rises from the bottom of the device against the foil to form the foil, but the maximum rise height of the punch that can be formed without cracks or pinholes after three consecutive forming times is the limit forming height of the material. (Mm). The height of the punch was changed at 0.5 mm intervals. Here, the overhang height of 8.0 mm or more was not considered to be good in moldability, and it was determined to be good, and less than 8.0 mm was determined to be bad.

-Density of intermetallic compound The intermetallic compound is cut in a parallel cross section (RD-ND surface) of the foil with a CP (Cross section polisher), and a field emission scanning electron microscope (FE-SEM: Carl Zeiss NVision40) is used. Was observed. For the “Al—Fe intermetallic compound having a particle size of 1 μm or more and less than 3 μm”, image analysis was performed on 5 fields of view observed at a magnification of ×2000, and the density was calculated. For the “Al—Fe intermetallic compound having a particle size of 0.1 μm or more and less than 1 μm”, 10 fields of view observed at ×10,000 magnification were subjected to image analysis to calculate the density. The calculation results are shown in Table 1.

As shown in Table 2, in Examples satisfying the requirements of the present invention, good results were obtained in elongation, tensile strength, and critical overhang height. The tensile strength satisfied 90 MPa or more in the directions of 0°, 45°, and 90° with respect to the rolling direction. On the other hand, good results were not obtained in Comparative Examples that did not satisfy any one or more of the requirements of the present invention.

Claims

Fe: 1.0 mass% or more and 1.8 mass% or less, Si: 0.09 mass% or more and 0.20 mass% or less, Cu: 0.005 mass% or more and 0.05 mass% or less, and Mn: It has a composition in which the content is regulated to 0.01% by mass or less, and the balance is Al and inevitable impurities, and in the crystal orientation analysis per unit area by backscattering electron diffraction (EBSD), a large tilt grain boundary with an orientation difference of 15° or more. (HAGBs) and the length of the low-angle grain boundaries (LAGBs) having an orientation difference of 2° or more and less than 15°, “HAGBs/LAGBs>2.0”, a Cu orientation density of 40 or less, and an R orientation density. An aluminum alloy foil which is 30 or less.
The aluminum alloy foil according to claim 1, wherein Si: more than 0.10 mass% and 0.20 mass% or less in the composition.
The aluminum alloy foil according to claim 1 or 2, wherein the elongation in each direction of 0°, 45° and 90° with respect to the rolling direction is 20% or more.
The crystal grains surrounded by a high-angle grain boundary with a misorientation of 15° or more have an average grain size of 10 μm or less and a maximum grain size/average grain size≦3.0. The aluminum alloy foil according to any one.
A method for producing an aluminum alloy foil according to any one of claims 1 to 4, wherein the aluminum alloy ingot having the composition according to claim 1 is homogenized at 520 to 560°C for 6 hours or more. After the homogenization treatment, hot rolling is performed so that the rolling finish temperature is 230° C. or higher and lower than 280° C., intermediate annealing is performed at 300 to 400° C. during the cold rolling, and then the final cold rolling rate. Is 90% or more, and the final annealing is performed at 250 to 350° C. for 10 hours or more.