JP6674362B2 - Aluminum alloy foil and method for producing the same - Google Patents

Description

  The present invention relates to an aluminum alloy foil and a method for producing the same. More specifically, the present invention relates to an aluminum alloy foil having excellent appearance and manufactured without an intermediate annealing step, and a method for manufacturing the same.

  Aluminum foil and aluminum alloy foil (hereinafter, also simply referred to as “foil”) are used as a thickness of about 5 to 200 μm for packaging daily necessities, foods, medicines and the like. This foil is often used by being bonded to polyethylene, vinyl, paper, resin, or the like. Aluminum foil and aluminum alloy foil used for such applications need to shield the contents to be packaged from moisture and ultraviolet rays in the air, and are required to be excellent in quality without pinholes and holes. You. In addition, since it is often used for packaging foods and medicines, the beautiful appearance is also required quality.

  While cost reduction is required for the aluminum foil and the aluminum alloy foil, omitting intermediate annealing in a cold rolling process is being studied. If the intermediate annealing can be omitted, energy costs and annealing equipment become unnecessary, and productivity is improved, which is extremely advantageous in terms of cost. Further, since the production delivery time is shortened, various proposals have been made for a production method in which the intermediate annealing is omitted.

For example, in Patent Document 1, Fe: 0.1 to 1.0 wt%, Si: 0.3 wt% or less, Cu: 0.10 wt% or less are essential components, Mn: 0.05 wt% or less, Mg: 0 0.01 wt% or less, Ti: 0.05 wt% or less, or one or two kinds of B: 0.01 wt% or less and Zr: 0.05 wt% or less are added, and the balance is Al After the ingot of the alloy consisting of ordinary impurities is homogenized, hot rolling is performed at an end temperature of 250 ° C. or more, and then cooled at a cooling rate of 50 ° C./hr or less to obtain a recrystallized structure. There has been proposed a method for manufacturing an aluminum foil base that is cold-rolled to a predetermined foil thickness without performing foil base annealing.
This production method suppresses work hardening by precipitating Fe and Si during cooling after hot rolling, thereby reducing the number of pinholes in polymerization rolling and the number of cuts in foil rolling.

Patent Literature 2 discloses an aluminum alloy ingot containing 0.2 to 2.8% by weight of Fe and 0.05 to 0.3% by weight of Si and the balance of Al and unavoidable impurities. A method for producing an aluminum alloy foil substrate in which chemical heat treatment, hot rolling, and cold rolling are performed in this order, wherein the thickness of the hot-rolled plate is 3 mm or less, and at least the final pass rise temperature of the cold rolling is 100 to There has been proposed a method for producing an aluminum alloy foil material which is controlled at 180 ° C.
This manufacturing method controls the cold rolling temperature to be high and suppresses work hardening, thereby reducing the number of pinholes in polymerization rolling and the number of cuts in foil rolling without performing intermediate annealing.

Patent Literature 3 discloses an aluminum alloy casting containing Fe: 0.5 to 2.5% by mass and Si: 0.01 to 0.3% by mass, with the balance being Al and unavoidable impurities. In the method for producing an aluminum alloy foil base, in which a lump is subjected to homogenization treatment and hot rolling, and then cold-rolled to a foil without performing intermediate annealing, the solid solution Fe is 10 to 200 ppm, A method for manufacturing an aluminum alloy foil having a molten Si ratio of 0.2 to 0.75 has been proposed.
In this production method, work hardening characteristics are controlled by controlling the amount of solid solution elements, thereby improving the rollability and reducing the number of pinholes generated.

Further, Patent Document 4 contains Fe: 0.8 to 2.0% by weight, regulates Si: 0.15% by weight or less, and adjusts the Fe / Si ratio to 15 or more. By subjecting an aluminum alloy ingot, each of which has an impurity element regulated to 0.05% by weight or less, to homogenization heat treatment and hot rolling, rolling to a foil product without intermediate annealing, and annealing with foil. A method for producing an aluminum foil having a crystal grain size of 15 μm or less has been proposed.
This manufacturing method is intended to prevent deterioration in strength, moldability and pinhole characteristics without reducing the number of crystallized substances by lowering the soaking temperature and controlling the holding time to a short time.

JP-A-63-18041 JP-A-11-217656 JP 2001-288524 A JP-A-3-120332

  However, the conventional method of manufacturing a foil without intermediate annealing has the following problems. As described above, in Patent Literatures 1 to 3, Fe and Si are precipitated during cooling after hot rolling, the cold rolling temperature is controlled to be high, the amount of solid solution Fe and the amount of solid solution Si are controlled. By doing so, the work hardening characteristics are controlled. Thereby, foil rolling is facilitated, foil breakage during foil rolling is suppressed, and pinhole characteristics are improved. Further, in Patent Document 4, without decreasing the number of crystallized substances, deterioration of strength and formability is suppressed, and pinhole characteristics are improved by suppressing deterioration of pinhole characteristics.

  However, not recrystallizing by the intermediate annealing means not refining the macrostructure of the foil. When the macro structure is coarse, a phenomenon occurs in which a streak pattern is observed in appearance on a mat surface (matte surface) that is freely deformed. For this reason, the foil manufactured without intermediate annealing has room for improvement in aesthetics compared to the foil manufactured by performing intermediate annealing, and the foil manufactured without intermediate annealing is suitable for specific applications. Was used only in a limited manner.

  The material structure of the hard foil is in a state of a crystal grain structure in which recrystallized grains formed in the hot rolling step or the intermediate annealing step are elongated in the rolling direction by the subsequent rolling step and foil rolling step. . Then, the aspect ratio (major axis / minor axis) of the crystal grains is a value corresponding to the total rolling ratio of rolling and foil rolling. Therefore, theoretically, the aspect ratio of the crystal grains of the hard foil manufactured without the intermediate annealing step is generally 300 or more, and the aspect ratio of the crystal grains of the hard foil manufactured through the intermediate annealing step is generally Is 150 or less. However, in a microstructure state having an aspect ratio exceeding 100, it is difficult to determine a crystal grain boundary by a microstructure observation method using an optical microscope or the like, and it is difficult to distinguish whether or not an intermediate annealing step has been performed.

  The present invention has been made in view of such a background, and an object of the present invention is to provide an aluminum alloy foil in which the occurrence of a streak pattern on a mat surface is suppressed without performing intermediate annealing, and a method for manufacturing the same. In the present invention, the streak pattern corresponds to an elongated material structure, is a very slight unevenness formed on the mat surface, and its presence is detected by oblique reflection.

Since the aluminum alloy ingot of the composition according to the present invention has a large Fe content, the presence of a large number of Al-Fe crystallized substances facilitates recrystallization even in hot rough rolling. However, since recrystallization and elongation are repeated between hot rough rolling passes, a coarse grain structure is likely to be formed if the condition control is insufficient. Furthermore, when this is hot-finish-rolled, if it is finished under the condition of less than 300 ° C. that does not recrystallize, the structure in hot rough rolling simply becomes a stretched state. Further, even when the recrystallization at 300 ° C. or more is completed, the elongated crystal grains formed before the rough rough rolling are recrystallized, that is, the same crystal orientation group is likely to be formed.
As a result of intensive studies by the present inventors, it has been found that the streaks on the mat surface detected during the polymerization rolling are a structure in which the hot rough rolling structure is elongated or a structure in which the same crystal orientation group is elongated. In the case of performing intermediate annealing during cold rolling, which is a conventional technique, since the accumulated strain amount is large, the state changes from the elongated state of the hot rough rolling structure to a fine recrystallized grain structure. Investigated that it had been resolved. That is, it has been found that it is necessary to obtain a fine recrystallized grain structure at the final stage of hot rough rolling in order to improve the detected matte surface pattern with respect to the stripes on the matte surface.

The aluminum alloy foil according to the present invention does not undergo an intermediate annealing step of annealing the hot-rolled sheet in a cold-rolling step of cold-rolling the hot-rolled sheet into a cold-rolled sheet, and An aluminum alloy foil produced without an intermediate annealing step of annealing the cold-rolled sheet in a foil rolling step of foil-rolling the hot-rolled sheet into a foil-rolled foil, Fe: 0.70 to 1. 40% by mass, Ti: 0.005 to 0.05% by mass, the balance being Al and inevitable impurities, and 90 ° in the angular spectrum on the mat surface of the aluminum alloy foil calculated by the following (1). It is assumed that the relative peak height in the direction is less than 0.29.
Relative peak height in the 90 ° direction = peak height in the 90 ° direction 最大 (maximum peak height at 0 to 20 ° and 160 to 180 °) (1)
(Wherein, 90 ° direction is the rolling direction of the aluminum alloy foil.)

Further, the aluminum alloy foil according to the present invention, without undergoing an intermediate annealing step of annealing the hot-rolled sheet in a cold-rolling step of cold-rolling a hot-rolled sheet into a cold-rolled sheet, and An aluminum alloy foil manufactured without an intermediate annealing step of annealing the cold-rolled sheet in a foil rolling step of foil-rolling the cold-rolled sheet into a foil-rolled foil, Fe: 0.70 1.40% by mass, Ti: 0.005 to 0.05% by mass, the balance being Al and unavoidable impurities, and the number of crystal grains having a tilt angle exceeding 30 ° on the surface is perpendicular to the rolling direction. In the direction, it is 2 / mm or less.

  According to such a configuration, in the aluminum alloy foil, generation of a streak pattern on the mat surface is suppressed.

The method for producing an aluminum alloy foil according to the present invention is the method for producing an aluminum alloy foil described above , wherein Fe: 0.70 to 1.40% by mass, and Ti: 0.005 to 0.05% by mass. A hot rolling step of hot-rolling an aluminum alloy ingot consisting of Al and inevitable impurities into a hot-rolled plate, and cold-rolling without annealing the hot-rolled plate. A cold rolling step as a rolled plate, a foil rolling step to foil roll the foil without rolling the cold-rolled sheet and a foil rolling step to polymerize and roll the foil rolled foil, The hot rolling step includes hot rough rolling and hot finishing rolling, and the final pass in the hot rough rolling is performed under the condition that the Z factor shown in the following (2) is 1.0E + 12 to 5.0E + 13. Shall be.

  According to such a procedure, the manufacturing method of the aluminum alloy foil performs the final pass in the rough rolling in the hot rolling step under the condition that the Z factor becomes a predetermined value, so that the final step of the hot rough rolling is performed. A fine recrystallized grain structure results. Thereby, generation of a streak pattern on the mat surface is suppressed.

The aluminum alloy foil of the present invention is excellent in productivity because it is not subjected to intermediate annealing, and the occurrence of streak patterns on the mat surface is suppressed.
ADVANTAGE OF THE INVENTION Since the manufacturing method of the aluminum alloy foil of this invention does not perform intermediate annealing, it is excellent in productivity and can obtain the aluminum alloy foil which suppressed generation | occurrence | production of a streak pattern on a mat surface.

It is a schematic diagram which shows an example of the measurement result of an angular spectrum. It is a schematic diagram explaining the sampling position at the time of calculating the number of crystal grains in which the inclination angle exceeds 30 degrees. It is an image (image of test material No. 2) of the foil surface (glossy side) for confirming the structure state of crystal grains having an inclination angle exceeding 30 °. It is an image (image of test material No. 6) of the foil surface (glossy side) for confirming the structure state of the crystal grains having an inclination angle exceeding 30 °.

Hereinafter, the aluminum alloy foil and the method for producing the same according to the present invention will be specifically described.
《Aluminum alloy foil》
<First embodiment>
The aluminum alloy foil contains predetermined amounts of Fe and Ti as essential components, with the balance being Al and unavoidable impurities. Further, the aluminum alloy foil defines a relative peak height in a 90 ° direction (hereinafter, appropriately referred to as a relative peak height) in an angular spectrum on a mat surface of the aluminum alloy foil.
Hereinafter, each configuration will be described.

[Fe: 0.70 to 1.40 mass%]
Fe is added to refine the recrystallized grains and control the strength and work hardening behavior of the aluminum alloy foil. If the Fe content is less than 0.70 mass%, the effect of improving the strength is not sufficient, and the crystal grains are coarse or insufficiently recrystallized, and the value of the relative peak height becomes large. On the other hand, if the Fe content exceeds 1.40% by mass, for example, even if work hardening stagnates, the absolute value of the strength becomes too high and foil rolling becomes difficult, which causes rolling cracks. Therefore, the content of Fe is set to 0.70 to 1.40% by mass. The Fe content is preferably 0.80% by mass or more, more preferably 0.90% by mass or more, from the viewpoint of making the recrystallized grains finer, more easily controllable in strength and work hardening behavior. From the viewpoint of facilitating foil rolling, the content is preferably 1.30% by mass or less.

[Ti: 0.005 to 0.05% by mass]
Ti is added to refine the ingot structure. If the Ti content is less than 0.005% by mass, the effect of refining the ingot structure is insufficient, the value of the relative peak height becomes large, and streaks on the mat surface are easily observed. On the other hand, when the content of Ti exceeds 0.05% by mass, the effect of refining the ingot structure is saturated, so that the cost increases and the economy is lacking. Therefore, the content of Ti is set to 0.005 to 0.05% by mass. The content of Ti is preferably 0.007% by mass or more, more preferably 0.009% by mass or more, from the viewpoint of further improving the effect of refining the ingot structure. From the viewpoint of cost reduction, the content is preferably 0.03% by mass or less, more preferably 0.02% by mass or less.

[Remainder: Al and unavoidable impurities]
In addition to the components described above, the remainder of the aluminum alloy foil consists of Al and inevitable impurities. As the unavoidable impurities, there is substantially no problem as long as they are contained within the range of impurities stipulated in the JIS standard of 8079 alloy and 8021 alloy, for example. Specifically, as unavoidable impurities, Si, Cu, Mn, Mg, Cr, Zn, Zr, V, Ni, Sn, In, Ga, or the like may be contained or added within a range not to impair the effects of the present invention. good. Specifically, Si: 0.30% by mass or less, Zn: 0.10% by mass or less, the other elements are each 0.05% by mass or less, and the total amount of other elements is 0.15% by mass or less. is there.

(Relative peak height in the 90 ° direction in the angular spectrum on the matte surface: less than 0.29)
In the foil according to the present embodiment, it is necessary to reduce the value of the relative peak height in the 90 ° direction in the angular spectrum on the mat surface in order to suppress the occurrence of the streak pattern on the mat surface. Specifically, the aluminum alloy foil has a relative peak height in the 90 ° direction in the angular spectrum on the matte surface of the aluminum alloy foil calculated by the following (1) of less than 0.29.

Relative peak height in the 90 ° direction = peak height in the 90 ° direction 最大 (maximum peak height at 0 to 20 ° and 160 to 180 °) (1)
Here, in the formula, the 90 ° direction is substantially the rolling direction of the aluminum alloy foil. The maximum peak heights at 0 to 20 ° and 160 to 180 ° mean the maximum peak heights in both the range of 0 to 20 ° and the range of 160 to 180 °.

  When the relative peak height is 0.29 or more, unevenness due to crystal grains elongated in the rolling direction is remarkable, and streaks on the mat surface of the foil are easily observed. Therefore, the relative peak height is less than 0.29. Further, in order to make it difficult to observe the streaks on the mat surface, the relative peak height is preferably set to 0.12 or less.

  The relative peak height is, as described above, the content of the alloy component in a predetermined range, and, as described later, by performing a final pass in hot rough rolling under predetermined conditions without performing intermediate annealing. Can be controlled.

Hereinafter, a method of calculating the relative peak height in the 90 ° direction in the angular spectrum on the mat surface will be described.
With respect to the foil obtained by performing the polymerization rolling, a sample of a predetermined size is cut out from an arbitrary position for inspection. Then, the sample is stuck on a glass plate, and a streak pattern evaluation on the mat surface is performed. The evaluation is carried out using a shape analysis laser microscope VK-X250 manufactured by KEYENCE CORPORATION according to ISO25178 and a violet laser with a measurement magnification of 1000 times and a visual field of 202 μm × 270 μm. The measurement is performed on the matte side of the foil.

  The so-called mat surface is a "ripple" rough surface extending in the rolling vertical direction, and when measured in the rolling direction, has an arithmetic average roughness Ra of about 0.2 to 0.4 μm defined in JIS B 0601: 2001. is there. On the other hand, the streak pattern, which is the subject of the present invention, is fine irregularities extending in the rolling parallel direction due to the material structure extending in the rolling direction. Both of the patterns are superimposed, and cannot be expressed by the arithmetic average roughness Ra, even if they can be detected optically.

According to the measurement by the laser microscope, the angle spectrum shows that the values of 0 ° and 180 ° are large, reflecting the “ripple” shape of the rough surface extending in the vertical direction of the rolling, and the fine irregularities extending in the parallel direction of the rolling. Is reflected, and the feature of a small peak at 90 ° is output. The state of the matte surface was defined as an angular spectrum (see FIG. 1) indicating the evaluation of oblique light reflection, where the rolling direction of the aluminum alloy foil was 90 °, and the width direction perpendicular to the rolling direction was 0 ° and 180 °. In this case, the streak pattern, which is the subject of the present invention, can be detected as a minute relative peak at 90 °.
In the present invention, the “90 ° direction” at the peak height in the 90 ° direction does not mean strictly 90 °, and there may be a deviation of about ± 5 ° due to measurement or sample variation. In addition, since the peak height of the angular spectrum varies depending on the measurement visual field, measurement is performed on a plurality of samples, and the average value is used.

<Second embodiment>
The aluminum alloy foil contains predetermined amounts of Fe and Ti as essential components, with the balance being Al and unavoidable impurities. In the aluminum alloy foil, the number of crystal grains having a tilt angle exceeding 30 ° on the surface is 2 / mm or less in a direction perpendicular to the rolling direction.
Hereinafter, each configuration will be described.

[Fe: 0.70 to 1.40 mass%]
Fe is added to refine the recrystallized grains and control the strength and work hardening behavior of the aluminum alloy foil. When the Fe content is less than 0.70 mass%, the effect of improving the strength is not sufficient, and the crystal grains are coarse or insufficiently recrystallized, and the number of crystal grains having a tilt angle exceeding 30 ° increases. On the other hand, if the Fe content exceeds 1.40% by mass, for example, even if work hardening stagnates, the absolute value of the strength becomes too high and foil rolling becomes difficult, which causes rolling cracks. Therefore, the content of Fe is set to 0.70 to 1.40% by mass. The Fe content is preferably 0.80% by mass or more, more preferably 0.90% by mass or more, from the viewpoint of making the recrystallized grains finer, more easily controllable in strength and work hardening behavior. From the viewpoint of facilitating foil rolling, the content is preferably 1.30% by mass or less.

[Ti: 0.005 to 0.05% by mass]
Ti is added to refine the ingot structure. If the content of Ti is less than 0.005% by mass, the effect of refining the ingot structure is insufficient, the number of crystal grains having an inclination angle exceeding 30 ° increases, and streaks on the mat surface are easily observed. On the other hand, when the content of Ti exceeds 0.05% by mass, the effect of refining the ingot structure is saturated, so that the cost increases and the economy is lacking. Therefore, the content of Ti is set to 0.005 to 0.05% by mass. The content of Ti is preferably 0.007% by mass or more, more preferably 0.009% by mass or more, from the viewpoint of further improving the effect of refining the ingot structure. From the viewpoint of cost reduction, the content is preferably 0.03% by mass or less, more preferably 0.02% by mass or less.

[Remainder: Al and unavoidable impurities]
In addition to the components described above, the remainder of the aluminum alloy foil consists of Al and inevitable impurities. The unavoidable impurities are the same as in the first embodiment, and a description thereof will be omitted.

(Number of crystal grains whose inclination exceeds 30 °: 2 / mm or less)
In the foil according to the present embodiment, in order to suppress the occurrence of a streak pattern on the mat surface, it is necessary to reduce the number of crystal grains having a tilt angle of more than 30 ° on the surface.
Here, “a crystal grain having a tilt angle of more than 30 °” is a crystal grain surrounded by a grain boundary having a tilt angle (a crystal orientation difference between adjacent crystal grains) of more than 30 ° on the surface of the foil.
If the value of the Z factor described later is insufficient, the recrystallized grains become coarse, and in this state, it is difficult to have a random orientation. Here, in the foil, the crystal grains are stretched in hot rolling, but the crystal grain size (normal recrystallized grains are defined as “the tilt angle exceeds 15 °”) is as small as about 100 μm or less (dimension in the width direction). is there. On the other hand, in a foil in which streaks are detected, the number of identical crystal orientation groups increases due to insufficient recrystallization, so that extremely coarse crystal grains (identical crystal orientation groups) exist when the tilt angle is defined as exceeding 30 °. . In a structure having an extremely large inclination angle, the deformation is different from that of the adjacent grains, so that the structure has minute irregularities extending in the rolling parallel direction. Among them, the irregularities in the width direction of the mat are detected as oblique light. On the other hand, a foil in which no streak is observed has almost no crystal grains having an inclination angle of more than 30 °, and does not have an uneven shape that can be detected with the naked eye.
As described above, the reason why the “grains having an inclination of more than 30 °” is specified is that the occurrence of a streak pattern on the mat surface of the foil is strongly dependent on the number of “grains having an inclination of more than 30 °”. This is because they have been found from numerous experimental results.
Note that the maximum value of the tilt angle is 65 ° due to the crystal structure.

  When the number of crystal grains having an inclination angle of more than 30 ° exceeds 2 / mm, stripes on the mat surface of the foil are easily observed. Therefore, the number of crystal grains having a tilt angle exceeding 30 ° is set to 2 / mm or less. The number of crystal grains having an inclination angle of more than 30 ° is preferably 1 / mm or less, more preferably 0 / mm, from the viewpoint of further suppressing generation of a streak pattern on the mat surface of the foil. The number of crystal grains is the number per 1 mm in the width direction (direction perpendicular to the rolling direction).

  The number of crystal grains having an inclination angle exceeding 30 ° is, as described above, the content of the alloy component within a predetermined range, and as described later, the final pass in hot rough rolling without performing intermediate annealing. It can be controlled by performing under predetermined conditions.

The number of crystal grains of the aluminum alloy plate is usually measured by buffing, electrolytic polishing, and electrolytic etching of the plate surface, and then observing polarized light using an optical microscope (for example, observation magnification of 100 times). In many cases, the “Barker method” is used.
However, for a thin foil having a thickness of 10 μm or less, the physical pretreatment as described above is difficult and the number of crystal grains is small, so that accurate measurement cannot be performed by the Barker method.
Therefore, the inventor of the present invention has proposed an EBSD method (Electron Back Scatter Diffraction) that can easily perform pretreatment and can measure the number of crystal grains having a desired inclination angle (in the present invention, an inclination angle exceeding 30 °) with high accuracy. ) Was employed as the measurement method.
For example, the number of crystal grains having a tilt angle of more than 30 ° can be measured by ion-etching the foil surface, using a scanning electron microscope to check the foil surface, and calculating by the EBSD method.

<< Production method of aluminum alloy foil >>
The method for manufacturing an aluminum alloy foil includes a casting step, a homogenization heat treatment step, a hot rolling step, a cold rolling step, a foil rolling step, and a polymerized foil rolling step, which are performed in this order. . However, no intermediate annealing is performed. Hereinafter, each step will be described.

(Casting process)
The casting step is a step of melting and casting an aluminum alloy by a standard method to produce an aluminum alloy ingot having the following composition.
The aluminum alloy contains, as essential components, 0.70 to 1.40% by mass of Fe and 0.005 to 0.05% by mass of Ti, with the balance being Al and unavoidable impurities.
The reasons for limiting the components of the aluminum alloy and the like are the same as those in the first and second embodiments of the aluminum alloy foil, and thus description thereof is omitted here.

(Homogenizing heat treatment process)
The homogenizing heat treatment step is a step of performing a homogenizing heat treatment on the aluminum alloy ingot. The homogenization heat treatment is performed to perform hot rolling on the ingot.
The homogenizing heat treatment is preferably performed under the condition that the temperature is maintained at a soaking temperature of 400 to 600 ° C. for 2 hours or more. In the present invention, the factor Z is specified, and the soaking temperature and the holding time are not particularly specified. However, when the soaking temperature is 400 ° C. or higher, hot rolling is easily performed. On the other hand, if the soaking temperature is 600 ° C. or lower, surface abnormalities such as seizure are less likely to occur on the surface of the aluminum alloy material by hot rolling, and pinholes are less likely to occur. Therefore, the homogenizing heat treatment is preferably performed at a soaking temperature of 400 to 600 ° C. The soaking temperature is preferably 500 ° C. or less from the viewpoint of further suppressing the occurrence of surface abnormality of the aluminum alloy material.

  The holding time of the homogenizing heat treatment is preferably short. However, if the holding time is 2 hours or more, the uniformity of the structure in the width direction and the length direction of the ingot is easily improved. Therefore, the homogenizing heat treatment is preferably maintained at a soaking temperature of 400 to 600 ° C. for 2 hours or more. In the present invention, the upper limit of the retention time is not particularly limited, but is preferably 24 hours or less from the viewpoint of economy. The holding time is more preferably 4 hours or more from the viewpoint of further improving the uniformity of the ingot in the width direction and the length direction. In addition, from the viewpoint of economy, it is more preferably 10 hours or less.

(Hot rolling process)
The hot rolling step is a step of hot-rolling the homogenized heat-treated aluminum alloy ingot into a hot-rolled plate, and includes hot rough rolling and hot finishing rolling.

[Rough hot rolling]
The hot rough rolling start temperature is not particularly defined. Further, the temperature during the hot rough rolling is not particularly defined. However, in order to control the Z factor to an appropriate range, the hot rough rolling start temperature is preferably in the range of 400 to 500 ° C. From the viewpoint of making it easier to control the Z factor to an appropriate range, the temperature during the hot rough rolling is preferably 390 ° C or higher, and more preferably 440 ° C or lower.

The hot rough rolling is performed in the final pass under the condition that the Z factor is 1.0E + 12 to 5.0E + 13. The proper range of the Z factor has been derived from many experiments. The Z factor of the final pass can be controlled by the work roll diameter, rolling speed, rolling reduction, rolling temperature, and the like.
In hot working, the deformation stress of aluminum is organized using the Z-factor over a wide strain rate range. The Z factor is Z represented by the equation (2).

The units in the formula (2) are strain rate: s ⁻¹ , activation energy: kJ · mol ⁻¹ , gas constant: J · mol ⁻¹ · K ⁻¹ , and absolute temperature: K.
In addition, it is reported that the grain size d of the sub-crystal grains formed during hot working complies with the equation (3), and it is considered that the grain size of the recrystallized grains in the next stage also follows the same relationship.

  Based on the above relationship, the present inventors have decided to control the Z factor in order to make the recrystallized grains during hot rolling fine. In other words, the research was carried out by paying attention to the fact that the grain size of the recrystallized grains can be reduced by appropriately controlling the strain rate and the temperature in the equation (2). Here, as the strain rate, an average strain rate obtained by Ford & Alexander's equation (4) was used.

In calculating the Z factor, the activation energy was selected to be 155 kJ · mol ⁻¹ , and the gas constant was 8.314 J · mol ⁻¹ · K ⁻¹ .

  When the Z factor is less than “1.0E + 12”, recrystallization is not completed or recrystallized grains remain coarse, the value of the relative peak height increases, and the number of crystal grains having a tilt angle exceeding 30 ° increases. In addition, the problem of streaks on the mat surface of the foil cannot be solved. On the other hand, the recrystallized grains become smaller as the Z factor increases, but under conditions where the Z factor exceeds “5.0E + 13”, the temperature after the completion of the hot rough rolling is not appropriate for performing the hot finish rolling in the next step. Since the temperature is lower than the temperature, hot finish rolling cannot be performed smoothly. On the other hand, when the Z factor exceeds “5.0E + 13”, the rolling reduction in the hot rough rolling end pass becomes too large, causing surface defects to cause pinholes in the foil. Therefore, the Z factor is set to 1.0E + 12 to 5.0E + 13.

[Hot finishing rolling]
The end temperature and the end plate thickness of the hot finish rolling are not particularly specified because they do not affect the stripe characteristics of the matte surface. However, in order to produce a foil without intermediate annealing, it is preferable that the working ratio is small in order to suppress work hardening, the finished plate thickness is preferably 3 mm or less, and more preferably 2.5 mm or less. The termination temperature is set to 300 ° C. or higher to form a recrystallized structure, and by sufficiently softening, work hardening is suppressed, which is suitable for the intermediate annealing omitting step. If the end temperature is lower than 300 ° C., foil rolling is possible, but the degree of work hardening is high, and there is a possibility that many pinholes are generated.

(Cold rolling process / Foil rolling process)
The cold rolling step is a step in which the hot-rolled sheet is cold-rolled without annealing to form a cold-rolled sheet. The foil rolling step is a step in which the cold-rolled sheet is rolled into a foil roll without annealing. Foil rolling is a type of cold rolling. That is, these steps are cold rolling and foil rolling steps in which the hot-rolled sheet is cold-rolled and foil-rolled into a foil (foil-rolled foil) without annealing.
The conditions for the cold rolling and the foil rolling are not particularly limited, and the rolling may be performed until the foil thickness becomes suitable for performing the superposed foil rolling in a later step.

(Polymerized foil rolling process)
The superposed foil rolling step is a step of superposingly rolling the rolled foil. In the polymerization rolling, two foils are stacked and supplied between upper and lower work rolls and rolled in the final pass of the foil rolling. Polymerized foil rolling is a type of cold rolling and foil rolling.
The conditions of the superposed foil rolling are not particularly limited, and the rolling may be performed until the desired aluminum alloy foil is obtained. The polymerized foil rolling is performed, for example, under conditions where the rolling reduction is 30 to 60%. Further, the foil thickness after the superimposed foil rolling is, for example, 5 to 40 μm.

  The method for manufacturing the aluminum alloy foil is as described above, but in the course of manufacturing the aluminum alloy foil, as long as it does not adversely affect each of the steps, before or after each of the steps, including other steps. You may. For example, it may include a surface smoothing step of chamfering an ingot, a foreign substance removing step of removing foreign substances on the surface of a plate or foil, and a defective product removing step of removing defective products generated in each step.

  The aluminum alloy foil manufactured in this manner has no streak pattern on the mat surface, or even if a streak pattern occurs on the mat surface, the streak pattern is hardly recognized as an external appearance by processing such as laminating in the next step. Therefore, for example, it can be used for packaging where importance is placed on the appearance of daily necessities, foods, medicines and the like.

  The embodiment for carrying out the present invention has been described above. Hereinafter, an example in which the effect of the present invention has been confirmed will be specifically described in comparison with a comparative example which does not satisfy the requirements of the present invention. Note that the present invention is not limited to this embodiment.

(Material preparation)
An aluminum alloy having the composition shown in Table 1 was melted and cast to a thickness of 500 mm by semi-continuous casting to obtain an ingot having the composition shown in Table 1. After facing the ingot, the ingot was subjected to a homogenizing heat treatment, and hot rough rolling was performed to a thickness of 50 mm. In the hot rough rolling, the work roll diameter, the rolling speed, the rolling reduction, and the rolling temperature were controlled, and the Z factor of the final pass was controlled to each value. After the completion of the hot rough rolling, a hot finish rolling was subsequently performed to finish with a 2.3 mm thickness. In the cold rolling, cold rolling and foil rolling were performed without performing intermediate annealing on the way to obtain 6.5 μm foil. In the foil rolling, rolling from the 14 μm thickness to the 6.5 μm thickness in the final foil rolling pass was defined as polymerization rolling. Each condition is as shown in Table 1.

[Evaluation]
(Evaluation by angular spectrum)
The following procedure was used to evaluate the occurrence of streak patterns on the matte surface of each aluminum alloy foil using an angular spectrum.
(1) About the foil obtained by performing the polymerization rolling, three samples (n = 3) having a size of about 20 mm × 20 mm were cut out from an arbitrary position.
(2) Each aluminum alloy foil was affixed on a flat glass plate (a flat slide glass) with the glossy side (glossy side) of the aluminum alloy foil down with tape at four corners as little as possible.
(3) Using a shape analysis laser microscope VK-X250 manufactured by KEYENCE CORPORATION, the angular spectrum on the mat side was measured using a violet laser according to ISO25178. At the time of measurement, the rolling direction of the aluminum alloy foil and the 90 ° direction of the angular spectrum were made to substantially match. The observation magnification at the time of measuring the angular spectrum was 1000 times, and the size of the visual field was 202 μm × 270 μm. FIG. 1 shows an example of the measurement result of the angular spectrum.
(4) In the semicircular chart showing the measurement results of the angular spectrum, the peak height in the 90 ° direction and the maximum peak height at 0 to 20 ° and 160 to 180 ° are measured, and the above formula (1) is used. The relative peak height in the 90 ° direction was determined.
(5) The relative peak heights in the 90 ° direction of the three sheets (n = 3) were averaged.

(Evaluation based on the number of crystal grains)
The following procedure was used to evaluate the occurrence of streak patterns on the matte surface of each aluminum alloy foil based on the number of crystal grains having a tilt angle exceeding 30 °.
Since it is difficult to measure the number of crystal grains by observing the matte surface side, the measurement was performed by observing the glossy surface side. Since the streak pattern on the matte surface reflects the state of the texture on the glossy side, by measuring the number of crystal grains on the glossy side, the state of occurrence of the streak pattern on the matt surface can be examined. .

(1) With respect to the foil obtained by performing the polymerization rolling, the center of the rolling width in the width direction, 1/4 part, and 3/4 part are each 20 mm in length and width from the left end of the foil as a reference for inspection. A sample having a size of about 20 mm was cut out (see FIG. 2).
(2) The surface oil was lightly removed by immersing the test material foil in an organic solvent.
(3) The surface of the foil was subjected to ion etching for 500 seconds at an accelerating voltage of 600 V and a current of 13 mA using ESCA (Electron Spectroscopy for Chemical Analysis, model JPS-9010MC) manufactured by JEOL Ltd.
(4) TSL-OIM (Orientation Imaging Microscope) which is a measurement software manufactured by TSL Solutions under the condition of an acceleration voltage of 20 KV using FESEM (Field Emission Scanning Electron Microscope, model JSM-700F) manufactured by JEOL Ltd. ) -Foil surface was measured with Data Collection version 5. The measurement was performed at 200 times (0.5 μm step, 400 μm × 200 μm).
(5) The measurement data was analyzed using TSL-OIM (Orientation Imaging Microscope) -Analysis version 7, which is analysis software manufactured by TSL Solutions.
(6) First, as a definition of a crystal grain having an inclination angle of more than 30 °, Grain Tolerance Angle: 30 °, pixel (step): 2, and when the azimuth difference between two pixels is 30 ° or less, those grains are defined. Pixels were assumed to be the same crystal grain.
(7) Crystal grains were observed using Unique Grain Color Quick Map, and the number of crystal grains having a tilt angle exceeding 30 ° per 1 mm in the width direction was obtained.
(8) The number of crystal grains having an inclination angle of more than 30 ° at the three locations (n = 3) described above was averaged.

  FIGS. 3 and 4 show the test material Nos. Obtained based on the methods (1) to (6). 2 (FIG. 3) and No. 2 6 (FIG. 4) are images of the foil surface (glossy surface side) showing the structure states of the “crystal grains having a tilt angle exceeding 30 °”, respectively, which are at the center in the width direction of the rolling width. From the images shown in FIGS. 3 and 4, in the mat surface streak evaluation described later, the five-point (No. 2) crystal grains having a tilt angle of more than 30 ° compared to the one-point (No. 6). It can be confirmed that there are few. The same applies to the 圧 延 and ／ parts of the rolling width in the width direction.

(Mat surface streak evaluation)
The appearance of the streak pattern on the mat surface of each aluminum alloy foil was visually evaluated.
The evaluation was performed on a five-point scale of 1 to 5 points by the naked eye judgment using oblique light. 1 point: remarkable streak pattern occurred, 2 points: many streak patterns occurred, 3 points: streak pattern occurred and rejected, 4 points: A streak pattern was slightly observed (lower limit of acceptance), 5 points: evaluation was made that no streak pattern was observed, and 4 or more points were judged as pass.
Among the above evaluations, 1 to 3 points were defective with respect to the streak pattern on the mat surface as in the prior art, 4 points and 5 points were no problem, and 5 points were better than 4 points. is there. The evaluation of 5 points indicates that no streak pattern is observed, and the evaluation of 4 points indicates that the streak pattern is no longer observed depending on the conditions of the laminating process in the next step.

  The above evaluation is shown in Table 1. In Table 1, "-" indicates that the evaluation could not be performed, or that the evaluation was not performed because the surface was not suitable as a foil due to poor surface. Those that do not satisfy the requirements of the present invention are underlined.

  As shown in Table 1, Nos. 1 to 5 were excellent in the surface condition of the mat surface because they satisfied the range of the present invention. That is, the streak pattern on the matte surface was not observed, or even if observed, was very slight, and exhibited a beautiful appearance. Also, in the evaluation by the angular spectrum, the relative peak height in the 90 ° (degree) direction was less than the predetermined value, and it was found that the generation of the streak pattern was suppressed. Also, in the evaluation based on the number of crystal grains, it was found that the number of crystal grains having a tilt angle exceeding 30 ° was equal to or less than a predetermined value, and that the generation of streak patterns was suppressed.

On the other hand, No. Nos. 6 to 13 did not satisfy the scope of the present invention, and thus the following results were obtained.
No. In Sample No. 6, the Ti content was insufficient and the value of the Z factor was low. Therefore, the evaluation by the angular spectrum and the evaluation by the number of crystal grains were poor, and a marked streak pattern was generated.
No. In No. 7, the value of the Z factor was appropriate but the Ti content was insufficient, and the evaluation by the angular spectrum and the evaluation by the number of crystal grains were poor, and a streak pattern occurred.
No. Sample No. 8 is appropriate for both the value of the Z factor and the content of Ti, but is insufficient in the content of Fe, so that the evaluation by the angular spectrum and the evaluation by the number of crystal grains are poor, and a streak pattern occurs.
No. In Sample No. 9, since the value of the Z factor was low, evaluation by the angular spectrum and evaluation by the number of crystal grains were poor, and a streak pattern occurred.

No. In the case of 10, both the value of the Z factor and the Ti content were appropriate, but due to the large content of Fe, the work hardening was large and the foil was broken during rolling to 6.5 μm, and the evaluation was not possible.
No. No. 11 had a low value of the Z factor. In this test material, the hot rough rolling start temperature was too high, and it was difficult to lower the temperature to an appropriate temperature range within a predetermined time. In addition, seizure occurred during hot rolling, which was unsuitable for foil.
No. 12, the value of the Z factor was high. This test material was rolled at a speed of 3000 mm / s and an end temperature of 360 ° C. (the hot finish rolling end temperature was 300 ° C.) in the final hot rough rolling pass. Was unsuitable for
No. No. 13 had a high value of the Z factor. This test material was subjected to rolling at a speed of 2500 mm / s and an end temperature of 360 ° C. (the end temperature of hot finish rolling was 300 ° C.) in the final pass of hot rough rolling. Was unsuitable for

  As described above, the present invention has been described in detail with reference to the embodiments and examples. However, the gist of the present invention is not limited to the above-described contents, and the scope of the rights is interpreted based on the description of the claims. There must be. Needless to say, the contents of the present invention can be modified or changed based on the above description.

Claims (3)

In a cold rolling step of cold-rolling a hot-rolled sheet into a cold-rolled sheet, without passing through an intermediate annealing step of annealing the hot-rolled sheet, and foil rolling the cold-rolled sheet An aluminum alloy foil manufactured without an intermediate annealing step of annealing the cold-rolled plate in a foil rolling step as a rolled foil,
Fe: 0.70 to 1.40 mass%, Ti: 0.005 to 0.05 mass%, the balance being Al and unavoidable impurities,
An aluminum alloy foil characterized in that the relative peak height in the 90 ° direction in the angular spectrum on the matte surface of the aluminum alloy foil calculated by the following (1) is less than 0.29.
Relative peak height in the 90 ° direction = peak height in the 90 ° direction 最大 (maximum peak height at 0 to 20 ° and 160 to 180 °) (1)
(Wherein, 90 ° direction is the rolling direction of the aluminum alloy foil.) In a cold rolling step of cold-rolling a hot-rolled sheet into a cold-rolled sheet, without passing through an intermediate annealing step of annealing the hot-rolled sheet, and foil rolling the cold-rolled sheet An aluminum alloy foil manufactured without an intermediate annealing step of annealing the cold-rolled plate in a foil rolling step as a rolled foil,
Fe: 0.70 to 1.40 mass%, Ti: 0.005 to 0.05 mass%, the balance being Al and unavoidable impurities,
An aluminum alloy foil, wherein the number of crystal grains having a tilt angle of more than 30 ° on the surface is 2 / mm or less in a direction perpendicular to the rolling direction. It is a manufacturing method of the aluminum alloy foil of Claim 1 or Claim 2, Comprising:
Hot rolled sheet obtained by hot rolling an aluminum alloy ingot containing Fe: 0.70 to 1.40% by mass and Ti: 0.005 to 0.05% by mass, with the balance being Al and unavoidable impurities Hot rolling process and
A cold rolling step of cold rolling the cold rolled sheet without annealing the hot rolled sheet,
A foil rolling step in which the cold-rolled sheet is foil-rolled without annealing to obtain a foil-rolled foil,
A polymerized foil rolling step of polymerizing and rolling the foil rolled foil,
The hot rolling step includes hot rough rolling and hot finishing rolling, and the final pass in the hot rough rolling is performed under the condition that the Z factor shown in the following (2) is 1.0E + 12 to 5.0E + 13. A method for producing an aluminum alloy foil, comprising: