JP6466317B2 - Aluminum alloy hard foil and method for producing the same - Google Patents

Description

The present invention relates to an aluminum alloy hard foil (hereinafter referred to as “hard foil” as appropriate) and a method for producing the same, and in particular, to an aluminum alloy hard foil capable of suppressing the occurrence of pinholes and a method for producing the same. Is.

  Aluminum foil and aluminum alloy foil are usually about 5 to 100 μm thick, such as packaging for daily necessities, foodstuffs, chemicals, etc., heat insulation for building materials, vehicles, ships, etc., and electrical equipment for capacitors, boards, etc. Used for applications.

Among various applications, it is widely used as a soft material for various containers, battery packs, etc. as a material that requires moldability, but as a hard material, it is used for a light embossed fence, etc. Stay on.
This is because the hard material of aluminum foil and aluminum alloy foil has poor workability.

  Various techniques have been proposed so far for the workability of aluminum materials.

  For example, in Patent Document 1, as essential elements, Si: 0.180 to 0.40 mass% (hereinafter simply referred to as%), Mg: 0.70 to 1.20%, Mn: 0.70 to 1 .20%, Fe: 0.30 to 0.70%, Cu: 0.10 to 0.30%, consisting of the balance Al and unavoidable impurities, the value of α showing the ultimate deformability is 0.25 or more An aluminum alloy plate for a bottle can excellent in the mouth curl bending workability, which is characterized by the above, has been proposed.

  Patent Document 2 contains 5 to 10 wt% of Mg, the area ratio of Fe-Al-based and Mg-Si-based crystallized products is 0.4% or less, and the average particle size of the crystallized products is 2 μm or less. In addition, an aluminum alloy plate excellent in formability characterized by an ultimate deformability of 0.58 or more has been proposed.

JP 2007-277589 A Japanese Patent Laid-Open No. 07-150284

  The technology proposed in Patent Document 1 is excellent in curling of the mouth curl as an aluminum alloy plate for a bottle can, and the technology proposed in Patent Document 2 is stretched as an aluminum alloy plate for an automobile body sheet. It is excellent in moldability such as flangeability and bending workability.

Unlike the plate materials described in Patent Documents 1 and 2, since the foil targeted by the present invention is a thin product of about 5 to 100 μm as described above, it is rolled at a high cold rolling rate to make it thin. There is a need to. And when manufacturing thin foil, the superposition | polymerization rolling which piles up and rolls two foils normally is given.
When the foil is thinned by this polymerization rolling, the aluminum surface is freely deformed on the mat surface where the two foils are superposed, so that it is difficult to avoid the mat surface becoming a rough surface. Further, since rolling oil is supplied between the roll and the foil from the viewpoint of the lubricity and the like of the polymerization rolling, it is difficult to avoid the occurrence of oil pits based on the presence of the rolling oil on the rolled surface of the foil. And since the foil becomes thin in the portion where the concave and convex portions on the mat surface coincide with the position of the oil pits on the rolling surface, there is a very high possibility that pinholes will start from this portion. .
Thus, on the principle of polymerization rolling, it was difficult to avoid the occurrence of pinholes in the foil subjected to polymerization rolling.

Then, this invention makes it a subject to provide the aluminum alloy hard foil which can suppress generation | occurrence | production of a pinhole, and its manufacturing method .

When the present inventor has conducted extensive research on the elongation of the foil, even if the elongation is reduced by rolling the foil at a high rolling rate, the elongation in the vicinity of the fracture portion, that is, the local elongation is increased. It was found that if it was possible, it became strong against local fracture. As a result, it is possible to suppress the occurrence of pinholes by performing superposition rolling on the foil, even if there are portions where the concave and convex concave portions of the mat surface coincide with the oil pit positions on the rolled surface and are thinned. all right.
In addition, it was found that if the local elongation of the foil can be increased, the processability of the foil can be improved.
The present invention has been completed based on the above matters.

That is, the aluminum alloy hard foil according to the present invention contains Fe: 0.80 to 1.40 mass%, the balance is Al and inevitable impurities, the ultimate deformability is α, and the thickness is tmm. In this case, α ≧ 7.0 × 10 ⁻¹ × t + 0.089 is satisfied.
Moreover, it is preferable that the aluminum alloy hard foil which concerns on this invention satisfy | fills t <= 0.050.
Moreover, the manufacturing method of the aluminum alloy hard foil which concerns on this invention is characterized by including a predetermined | prescribed process.

  According to this aluminum alloy hard foil, since it contains a predetermined amount of Fe and the ultimate deformability and thickness satisfy a predetermined relational expression, the local elongation increases and the generation of pinholes can be suppressed. it can.

The aluminum alloy hard foil according to the present invention has an alloy component content within a predetermined range, and the ultimate deformability and thickness satisfy a predetermined relational expression, thereby increasing local elongation and suppressing the generation of pinholes. can do.
In addition, the aluminum alloy hard foil according to the present invention has a large local elongation and excellent workability.
Moreover, the manufacturing method of the aluminum alloy hard foil which concerns on this invention can manufacture the said aluminum alloy hard foil.

It is a schematic diagram of the scribed circle printed on the foil surface in order to calculate the ultimate deformability of aluminum alloy hard foil. In addition, only two examples are shown from the shortest distance L. It is a graph for calculating the ultimate deformability of the specimen 2-4.

  Hereinafter, the form for implementing the aluminum alloy hard foil which concerns on this invention is demonstrated in detail.

[Aluminum alloy hard foil]
The hard foil according to the present embodiment contains a predetermined amount of Fe, the balance is Al and inevitable impurities, the content of the alloy component is within a predetermined range, and the ultimate deformability and the thickness satisfy a predetermined relational expression. .
In addition, although the thickness of the hard foil which concerns on this embodiment is not specifically limited, For example, it is 5-100 micrometers, Preferably it is 80 micrometers or less, More preferably, it is 50 micrometers or less (0.050 mm or less). Moreover, the hard foil which concerns on this embodiment is a direct material manufactured without performing intermediate annealing as it mentions later.
Hereinafter, the reason why the content of the alloy component of the hard foil according to the present embodiment is numerically limited and the reason why the predetermined relational expression between the ultimate deformability and the thickness is set will be described.

(Fe: 0.70 to 1.40 mass%)
Fe is a component for controlling the strength and work hardening behavior of the hard foil, and forms an Al—Fe-based intermetallic compound, and has a substructure (a grain boundary where the inclination angle between adjacent crystal grains exceeds 2 °. Is added to increase the value of the ultimate deformability. When the Fe content is less than 0.70% by mass, the sub-structure is not sufficiently refined. As a result, the value of the ultimate deformability is not sufficiently increased, and the generation of pinholes cannot be sufficiently suppressed. The properties are not excellent. On the other hand, when the Fe content exceeds 1.40% by mass, a coarse intermetallic compound of Al—Fe type is formed, and as a result, the value of ultimate deformability is not sufficiently increased, and pinholes are sufficiently generated. In addition, the processability is not excellent.
Therefore, the Fe content is 0.70 to 1.40 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 substructure fine and increasing the value of ultimate deformability. Further, the content of Fe is preferably 1.30% by mass or less from the viewpoint of suppressing the formation of a coarse intermetallic compound and suppressing a decrease in the value of ultimate deformability.

(Balance: Al and inevitable impurities)
The hard foil according to the present embodiment may contain an element other than Fe as an inevitable impurity within a range defined by alloy numbers 8079 and 8021 of JISH4000: 2014. Specific examples of the inevitable impurity element include Si, Cu, Mn, Mg, Cr, Zn, Ti, Zr, V, Ni, Sn, In, and Ga. The content of these elements is individually Si: 0.2% by mass or less, Cu: 0.03% by mass or less, Mg: 0.01% by mass or less (preferably Mg: 0.005% by mass or less), The content of elements other than Si, Cu, and Mg is preferably individually controlled to 0.05% by mass or less, and in total, 0.15% by mass or less, and if within this range, contained as an unavoidable impurity The effect of the present invention is not hindered not only when it is added, but also when it is positively added.

(Extreme deformability)
In order to suppress the occurrence of pinholes in the hard foil according to the present embodiment, in the present embodiment, a relational expression related to ultimate deformability is defined as an important index.
This ultimate deformability is different from, for example, the normal elongation calculated by measuring the gauge distance as 50 mm in a JIS No. 5 tensile test piece, and the elongation when the gauge distance is assumed to be 0 mm, that is, the locality of the material. Shows growth. Specifically, the ultimate deformability indicates the local elongation of the flange tip portion that is expected to break when performing the stretch flange processing test.

The ultimate deformability satisfies the equation (1) of φ = α · Lβ (φ: true strain at the gauge distance L in the tensile test, α: ultimate deformability, β: strain gradient in the vicinity of the fracture), 1) can be expressed as equation (2) where ln (φ) = ln (α) + βln (L). And ultimate deformability can be calculated | required from the intercept of the regression curve at the time of logarithm plotting the gauge distance L and true distortion (phi).
The true strain here may be a nominal strain value.

Usually, the elongation of the hard foil becomes smaller as it becomes thinner. For example, it becomes 5% or less for a hard foil having a thickness of 0.050 mm or less. However, if the value of the ultimate deformability of the hard foil is sufficiently increased, for example, if the thickness is about 0.015 mm and the ultimate deformability is 0.100 or more, local elongation increases, Occurrence can be suppressed.
As a result of confirming various samples, when α ≧ 7.0 × 10 ⁻¹ × t + 0.089 (α: ultimate deformability, t: thickness (mm)) is satisfied, hard pinholes are sufficiently generated. It was confirmed that it can be suppressed.
The upper limit of the limit deformability value is not particularly limited, but is, for example, 0.400 or less.

  In addition, as described above, the ultimate deformability is large in the cold rolling process and the foil rolling process while controlling the temperature of the homogenization heat treatment while keeping the content of the alloy component within a predetermined range and as described later. It can be controlled by applying plastic strain to the foil.

  The hard foil according to the present embodiment is as described above, but the other characteristics that are not clearly specified are not particularly limited as long as they are conventionally known and exhibit the effects obtained by the characteristics. Needless to say.

[Method for producing aluminum alloy hard foil]
Next, the manufacturing method of the hard foil which concerns on this embodiment is demonstrated.
The hard foil according to the present embodiment includes a casting process, a homogenization heat treatment process, a hot rolling process, a cold rolling process, and a foil rolling process, and is performed in this order. However, intermediate annealing is not performed.
Hereinafter, each step will be described.

(Casting process)
The casting step is a step of producing an aluminum alloy ingot by melting and casting the aluminum alloy having the above-described component composition by a conventional method.

(Homogenization heat treatment process)
The homogenization heat treatment step is a step of homogenizing heat treatment of the aluminum alloy ingot. The homogenization heat treatment is performed in order to perform hot rolling on the ingot.
When the soaking temperature of the homogenization heat treatment is less than 400 ° C., hot rolling becomes difficult and a fine intermetallic compound is hardly formed. On the other hand, if the soaking temperature exceeds 500 ° C., the refinement of the substructure becomes insufficient in the cold rolling process, and the value of the ultimate deformability is not sufficiently increased.

A shorter holding time of the homogenization heat treatment is preferable. However, if the holding time is less than 2 hours, the structure in the width direction and the length direction of the ingot is not uniform, and a fine intermetallic compound is hardly formed. On the other hand, if the holding time exceeds 24 hours, it is not preferable from the viewpoint of economy, and a fine intermetallic compound grows, resulting in a large size and a reduced density. As a result, the value of the ultimate deformability is sufficiently large. Don't be.
Therefore, the homogenization heat treatment is preferably maintained at a soaking temperature of 400 to 500 ° C. for 2 to 24 hours.
The holding time of the homogenizing heat treatment is preferably 20 hours or less from the viewpoint of economy, and is 4 hours or more from the viewpoint of further improving the uniformity of the structure in the width direction and the length direction of the ingot. Is preferred.

(Hot rolling process)
The hot rolling step is a step of hot rolling an aluminum ingot subjected to homogenization heat treatment to form a hot rolled plate, and includes hot rough rolling and hot finish rolling.
The conditions for hot rolling are not particularly limited. For example, hot rough rolling in which the start temperature is 400 to 500 ° C. and the end temperature is 390 to 440 ° C., the end temperature is 300 ° C. or more, and the plate thickness is What is necessary is just to make it the conditions of performing hot finish rolling which is 3 mm or less (preferably 2.5 mm or less).

(Cold rolling process, foil rolling process)
A cold rolling process and a foil rolling process are processes which give a cold rolling and foil rolling to hard foil, without annealing a hot rolled sheet. And in this cold rolling process and foil rolling process, a fine substructure is increased by giving a big plastic strain to a hot rolled sheet. For the rolling process performed in the cold rolling process and the foil rolling process, when the sheet thickness after hot rolling is t ₀ mm and the foil thickness after foil rolling (in other words, before polymerization rolling) is tmm, ln (t _If the value of ( ₀ / t) is less than 4.0, sufficient plastic strain cannot be imparted to the material, and the fine substructure is not sufficiently formed. As a result, the value of the ultimate deformability is sufficiently large. Don't be.
Therefore, the rolling process performed in the cold rolling process and the foil rolling process is ln (t ₀ / t) when the sheet thickness after hot rolling is t ₀ mm and the foil thickness after foil rolling is tmm. It is preferable to carry out under the condition that the value is 4.0 or more.

(Other processes)
Although the manufacturing method of the hard foil which concerns on this embodiment is as having demonstrated above, a superposition | polymerization rolling process is normally provided after a foil rolling process.
The polymerization rolling step is a step of polymerizing and rolling the hard foil after foil rolling. The superposition rolling is a method in which two foils are stacked and supplied to a roll and rolled in the final pass of the foil rolling.
The conditions for the polymerization rolling are not particularly limited, and the rolling may be performed until the hard foil has a desired foil thickness. For example, the polymerization rolling is performed under a condition that the rolling rate is 30 to 60%. Moreover, the foil thickness after superposition | polymerization rolling is 5-40 micrometers as an example.

  Furthermore, when manufacturing the hard foil which concerns on this embodiment, in the range which does not have a bad influence on each said process, you may include another process between each process, or before and after. For example, a surface smoothing step for chamfering the ingot, a foreign matter removing step for removing foreign matter on the surface of the plate or foil, a defective product removing step for removing defective products generated in each step, and the like may be included.

  In addition, as for conditions that are not clearly shown in the respective steps, it is sufficient to use conventionally known conditions, and it is needless to say that the conditions can be appropriately changed as long as the effects obtained by the processing in the respective steps are exhibited.

  Next, the hard foil according to the present invention will be specifically described by comparing an example satisfying the requirements of the present invention with a comparative example not satisfying the requirements of the present invention.

[Sample material preparation]
Aluminum alloys having the compositions shown in Tables 1 and 2 were melted and cast into a 500 mm thickness by semi-continuous casting to form ingots having the compositions shown in Tables 1 and 2. After chamfering the ingot, homogenization heat treatment (temperature: shown in Tables 1 and 2, time: 4 hours) was applied, and hot rolling was performed to the thicknesses shown in Tables 1 and 2. Then, cold rolling and foil rolling were performed so that the processing rates shown in Tables 1 and 2 were obtained, and a test material (hard foil) was manufactured.
In addition, what was shown as "directly" in Tables 1 and 2 was not subjected to intermediate annealing, and the end temperature of these hot rolling was 300 to 330 ° C. On the other hand, those indicated as “medium blunt” in Tables 1 and 2 were subjected to intermediate annealing (420 ° C. × 4 hr) during the cold rolling, and the end temperature of these hot rolling was 270 ° C. . And about “t ₀ ” of ln (t ₀ / t) in Tables 1 and 2, what is indicated as “directly” is the thickness at the end of hot rolling, and is indicated as “medium blunt”. The thing was the board thickness at the time of intermediate annealing.

[Measurement items and evaluation items]
(Extreme deformability)
In order to determine the ultimate deformability, the following tensile strength and elongation tests were performed.
The tensile strength and elongation tests were performed using B-type test pieces in accordance with the Light Metal Association Standard LIS AT5. That is, a strip-shaped test piece of 15 mm width × about 200 mm length was cut out from a test material that is a hard foil (the foil before polymerization rolling in Table 2) so that the tensile direction is parallel to the rolling direction. A distance of 100 mm was used as a gauge distance. In the test, a 5965 dual column tabletop test system (load capacity 5 kN) manufactured by Instron was used to perform the test in the 1 kN range, and the measurement and analysis were performed using Bluehill, which is included software.

Before the tensile strength and elongation tests, a scribed circle having a diameter of 5 mm as shown in FIG. 1 was printed. Then, after the test (after breakage of the test material), the broken part was attached, and the nominal strain (elongation) φ with respect to the gauge distance L around the broken part was measured. For the measurement of the gauge distance L and the nominal strain φ, using a three-dimensional shape measuring device (QSL2010 / AFB manufactured by Mitutoyo Corporation), the cursor is aligned at an observation magnification of 30 times, and the accuracy of 1 μm is obtained by moving the stage. It carried out in. Based on the measured value and ln (φ) = ln (α) + βln (L) in the formula (2), the ultimate deformability α was determined.
The gauge length L was set to 4.9748 mm, 12.460 mm, 19.1056 mm, 26.2174 mm, 33.3605 mm, 40.3317 mm, and 47.4149 mm.

A detailed calculation method of the ultimate deformability will be described using the specimen 2-4.
First, the nominal strain φ (= (L after test−L ₀ before test) / L ₀ before test) at each gage distance L was calculated. The gauge distance L and the nominal strain φ were converted into logarithmic values and plotted as shown in FIG. And the regression line was calculated | required by the least square method from each plot of FIG. The value of α was determined by determining that the regression line intercept −2.4744 was ln (α).

(Stretch flange processing test)
Ten types of holes (d) were drilled in a 0.30 mm pitch from 4.00 mm to 6.70 mm on the foil having the thickness shown in Table 1. The clearance of the punching die was set to plate thickness + 5 μm. Flange processing was performed by using a burring mold 1 or a burring mold 2 and applying mineral oil to the mold as appropriate in order to improve lubrication.
The burring mold 1 has a structure in which the diameter D is 7.43 mm, the punch shape is conical at the tip (cone height 10 mm), the punch diameter is D-0.10 mm, and the die diameter is D + 0.10 mm. Met. The burring mold 2 has a structure in which the diameter D is 6.10 mm, the punch shape is a conical tip (conical part height 10 mm), the punch diameter is D-0.10 mm, and the die diameter is D + 0.10 mm. Met.
The stretch flange processing rate was calculated by the formula: processing rate (%) = 100 × (D−d) / d. Depending on the combination of the hole diameter and the mold, 21.8% (workability 1 point), 24.5% (workability 2 points), 28.1% (workability 3 points), 32.6% (working) 4 points), 35.1% (5 points of workability), 41.9% (6 points of workability), 42.9% (7 points of workability), 51.6% (8 points of workability) Stretch flange processing at 8 processing rates was performed.

Stretch flange processing at each processing rate was carried out at 10 locations, and when no cracks were observed at 7 or more of the 10 locations, it was determined that processing at that processing rate was “no problem”.
The score at the highest processing rate at which each sample material was determined to be “no problem” was defined as “workability score”, and when the score was 5 or more, the workability was evaluated as “◯”.

(Pinhole evaluation)
In a state where two test materials, which are hard foils shown in Table 2, were stacked, polymerization rolling was performed so as to have a thickness of 6.0 μm.
The foil obtained by performing the polymerization rolling under the above-mentioned conditions is placed on a glass plate of a light box in a dark room, irradiated with light of 800 lux or more from the bottom of the glass, and the number of pinholes per 1 m ² visually. Counted. Further, when the number of pinholes exceeded 100 / m ² , the number of pinholes per 0.316 m square (0.1 m ² ) was counted and made 10 times.
In addition, as pinhole evaluation, 50 piece / m < ² > or less was set as the pass.

  Tables 1 and 2 show the components of the aluminum alloy, the measurement items, and the results of the evaluation items.

[Examination of results]
First, the test materials 1-1 and 1-2 shown in Table 1 satisfy the requirements specified by the present invention, and therefore the processability is excellent.

On the other hand, about the test materials 1-3 to 1-7 of Table 1, since the requirements which this invention prescribes | regulates are not satisfy | filled, the following results were obtained.
For the specimens 1-3 and 1-4, the ultimate deformability did not satisfy the relational expression defined by the present invention, and therefore the workability was “x”.
With respect to the specimen 1-5, the Fe content was small, and the ultimate deformability did not satisfy the relational expression defined by the present invention, so that the workability was “x”.
For the test materials 1-6 and 1-7, the Fe content is large and the ultimate deformability does not satisfy the relational expression defined by the present invention, so that the workability is "x". It was.

  Next, with respect to the test materials 2-1 and 2-2 in Table 2, it is assumed that the local elongation is increased because the requirements specified by the present invention are satisfied. As a result, it was possible to suppress the occurrence of.

On the other hand, for the specimens 2-3 and 2-4 in Table 2, since the ultimate deformability does not satisfy the relational expression defined by the present invention, it is assumed that the local elongation is not large, As a result, the result was that the occurrence of pinholes could not be suppressed.
For the specimen 2-5, since the Fe content is small and the ultimate deformability does not satisfy the relational expression defined by the present invention, it is assumed that the local elongation is not increased, and as a result, As a result, the occurrence of pinholes could not be suppressed.
With respect to Test Material 2-6, since the Fe content was large, rolling cracks occurred and pinhole evaluation could not be performed.

  From the above results, it was confirmed that the aluminum alloy hard foil according to the present invention can suppress the generation of pinholes and is excellent in workability.

Claims (3)

Fe: 0.80 to 1.40% by mass, the balance being Al and inevitable impurities,
An aluminum alloy hard foil characterized by satisfying α ≧ 7.0 × 10 ⁻¹ × t + 0.089 when the ultimate deformability is α and the thickness is tmm.   The aluminum alloy hard foil according to claim 1, wherein t ≦ 0.050 is satisfied. A method for producing an aluminum alloy hard foil according to claim 1 or claim 2,
A casting process for producing an aluminum alloy ingot;
A homogenization heat treatment step of holding the aluminum alloy ingot at a soaking temperature of 400 to 500 ° C. for 2 to 24 hours;
Hot rolling is performed after the homogenization heat treatment step, and the sheet thickness is 2.5 mm or less;
The thickness after the hot rolling step is t ₀ mm, and ln (t ₀ / T) including a cold rolling step and a foil rolling step of 4.0 or more,
The manufacturing method of the aluminum alloy hard foil characterized by not performing intermediate annealing.

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