JPS61170549A - Production of aluminium foil - Google Patents

Abstract

PURPOSE:To obtain the Al foil excelling in foil rollability and having fine crystal grains by subjecting an Al alloy plate having a prescribed composition to primary annealing at the slow rate of heating and temp. rise, to cold rolling, and then to short-time secondary annealing at the rapid rate of heating and temp. rise. CONSTITUTION:The plate having a composition consisting of, by weight, 0.1-0.8% Fe, 0.003-0.1% Ti, and, as impurities, <=0.50% Si, <=0.10% Cu, <=0.10% Mn, <=0.05% Mg, and the balance Al with other inevitable impurities is used as starting material. The plate is subjected to primary annealing to be heated to 280-400 deg.C at <=100 deg.C/hr temp. rise rate and held there for 0.5-48hr, which is then cold-rolled at >=about 50% draft and is succeedingly subjected to secondary annealing to be heated to 280-425 deg.C at >=1 deg.C/sec temp. rise rate and held there for a short period of <=10min. In this way, the foil hardly causing occurrence of pin holes by foil rolling can be obtained.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a method for producing an aluminum foil base, and more specifically, it has good rolling properties, fewer pinholes occur during foil rolling, and has fine crystal grains. The present invention relates to a method for manufacturing an aluminum foil substrate that is less likely to cause appearance defects such as streak defects due to

2. Description of the Related Art Conventionally, the method for producing aluminum foil, which is generally used for packaging materials, is to use JIS 1070 alloy or JIS 1N30 alloy as a raw material, cast a slab from the molten aluminum by a semi-continuous casting method, and then hot-roll the aluminum foil. After rolling and cold rolling to a thickness of about 0.4 to 111 (thickness for so-called foil stock), annealing is performed at a temperature higher than the recrystallization temperature (this is called foil annealing). (also referred to as intermediate annealing in relation to later foil rolling) to obtain an aluminum foil base, and then cold rolling (so-called foil rolling) to the aluminum foil base to obtain a 0.05 to 0.0
．． A common method is to obtain a final aluminum foil by making the aluminum foil approximately 0.005 - thick and then annealing it at a temperature of approximately 300 to 500° C. (referred to as foil annealing).

Here, during the foil annealing, 1IltRI! In the past, it was common to perform stationary annealing (batch annealing), but recently, with the aim of improving productivity and reducing costs, annealing is performed while the coil is continuously unwound. Continuous annealing is increasingly being applied.

Problems to be Solved by the Invention Aluminum foils used as packaging materials require a certain degree of moisture permeability and light shielding properties to protect the contents, and therefore are required to have as few pinholes as possible. . The occurrence of pinholes is greatly affected by the rollability during foil rolling. That is, as the foil rolling progresses, the rollability decreases due to work hardening, and the thinner the foil becomes, the more pinholes will occur. Therefore, it is necessary to obtain a foil base with good foil rolling properties in order to reduce the occurrence of pinholes.

On the other hand, aluminum foil used as a packaging material is required to have a good surface appearance, that is, to have few appearance defects. Typical appearance defects include ring-shaped patterns that occur parallel to the rolling direction during foil rolling, so-called streak patterns, and the surface of the overlapped surface (matte surface) when foil rolling is performed by lap rolling. There is roughness etc. It is known that the above-mentioned streak pattern is closely related to the crystal grain size and occurs when the crystal grains are coarse or the crystal grain sizes are non-uniform.

It is also known that the surface roughness of the overlapping surfaces during overlapping rolling is influenced by the size of the crystal grains, and the roughness becomes more significant as the grains become larger. Furthermore, if the crystal grains are extremely coarse, the crystal grain shape itself may appear on the foil surface. Therefore, in order to prevent appearance defects such as streak patterns and roughness of the laminated surfaces, it is necessary to make the crystal grains fine and uniform at the stage of forming the foil base before rolling the foil.

However, in the conventional method of manufacturing aluminum foil, as mentioned above, there are demands to ensure good foil rolling properties mainly to reduce the occurrence of pinholes during foil rolling, and to mainly reduce appearance defects such as streaks. It has been difficult to obtain an aluminum foil base that fully satisfies the requirements for grain refinement to achieve this goal.

That is, as already mentioned, foil annealing (medium l!l annealing)
Recently, continuous annealing has been increasingly used instead of stationary annealing. In this continuous annealing, the plate continuously passes through an atmosphere maintained at a predetermined temperature, so compared to stationary annealing, the heating rate is higher, the holding time at that temperature is shorter, and the cooling rate is faster. It is also known that the crystal grains are made finer than in stationary annealing because the heating temperature increase rate is particularly high.

Therefore, when continuous annealing is applied to foil annealing, productivity not only improves compared to stationary annealing, but also
It is possible to obtain a foil material with much finer crystal grains than in the case of stationary annealing, and it is therefore possible to prevent the occurrence of streaks during foil rolling and the occurrence of surface roughness on the overlapping surfaces during overlapping rolling.

However, continuous annealing requires rapid heating and short holding time as described above, making it difficult to ensure sufficient foil rollability.

In other words, the foil rollability is mainly influenced by the amount of solid solution of Fe in the ^i matrix, and the larger the amount of solid solution of Fe, the more
Work hardening during foil rolling increases, resulting in decreased rollability and the formation of pinholes.

Generally, at the end of hot rolling, a large amount of Fe is solidly dissolved in the ^g matrix, and when conventional stationary annealing is applied, a long period of stationary annealing at approximately 260 to 430°C is required after cold rolling. By annealing, it was possible to precipitate a large amount of Fe, significantly reduce the amount of solid 11Fe, and obtain excellent foil rolling properties. However, as mentioned above, continuous annealing requires rapid heating and short holding time, so when continuous annealing is applied to foil annealing, solid solution Fe cannot be sufficiently precipitated. Therefore, it was inevitable that some pinholes would occur during foil rolling.

This invention has been made against the background of the above circumstances, and has fine and uniform crystal grains that do not cause appearance defects such as streaks caused by foil rolling or surface roughness of the overlapping surfaces during overlapping rolling. The object of the present invention is to provide a method for producing an aluminum foil substrate which has good foil rolling properties and significantly reduces the occurrence of pinholes during foil rolling.

Means for Solving the Problems The inventors of the present invention have repeatedly conducted various experiments and studies in order to achieve the above-mentioned objective, and as a result, the inventors have found that primary annealing using a slow heating temperature increase rate,
Subsequently, by combining a fast heating temperature increase rate after cold rolling and secondary annealing with short heating, an aluminum foil substrate with good foil rolling properties and fine crystal grains can be manufactured. The present invention was completed based on this discovery.

Specifically, the aluminum foil fabric manufacturing method of this invention includes:
Fe001~0.8% by weight, T i 0.003
Contains ~0.1% and 0.5 of 81 as an impurity
0% or less, CU 0.10% or less, Mn 0.10% or less, Mg 0.05% or less, and the remainder is A.
1 and other unavoidable impurities at a heating rate of 100°C/hr or less.
Primary annealing is performed by heating to a temperature within the range of 400°C and holding at the temperature within that range for 0.5 to 48 hours, followed by cold rolling at a rolling rate of 50% or more, and further 1°C/S.
It is characterized by performing secondary annealing in which the material is heated to a temperature in the range of 280 to 425° C. at a temperature increase rate of E or more and held at the temperature within that range for a short time of 10 minutes or less.

DETAILED DESCRIPTION OF THE INVENTION First, the reasons for limiting the material components in the aluminum foil production method of the present invention will be explained.

Fe: 1"e is an element effective in refining the recrystallized grains of the foil base and improving its strength, and is also an essential element in the case of this invention, but if it is less than 0.1%, these effects cannot be obtained. On the other hand, 0.
If the content exceeds 8%, corrosion resistance will decrease. Therefore, the content of Fe was set within the range of 0.1 to 0.8%.

T1: T1 is an effective element for uniformly refining the ingot structure, but if its content is less than 0.003%, the refining effect cannot be obtained, while if it is added in excess of 0.1%, 0.003 to 0, since not only the effect of refining the ingot structure will be saturated, but also coarse compounds will be generated and impair rolling properties.
．． It was set within the range of 1%. By adding Naori at the same time as T1, the effect of refining the ingot structure of T1 is further increased, so B may be added in combination with Ti within the range of 50E)El- or less. However, if L/B exceeds 50Del■, T
i 82 coarse intermetallic compounds are mixed in and the rolling properties are measured.

Si: Si is an impurity element that is inevitably mixed in from the Al base metal. Since the solid solubility of St in Al is extremely large, the entire amount of St mixed as an impurity usually becomes solid solution S1, causing work hardening during rolling and reducing rollability. Therefore, it is preferable that 81 be as small as possible, but since there is no practical problem up to 0.5%, the upper limit of Si is set at 0.5%.

Cu, Mn1M0: These elements are all dissolved as impurity elements in the A1 matrix and reduce the rollability of the foil.Moreover, the amount of precipitation during the intermediate annealing treatment is small, so the foil has excellent rollability. In order to obtain a foil fabric, it is preferable to reduce these contents as much as possible, and from this point of view, Cu and Mn should each be 0.10% or less, and Mg should be 0.10% or less.
It was decided to limit it to 0.5% or less.

In addition to the above-mentioned components, Al and other unavoidable impurities may be used.
(2), Ni, Na, etc.) is preferably in a total amount of less than 0.10%.

Next, the manufacturing method of the present invention will be explained.

In the method of the present invention, a plate material having the above-mentioned components is subjected to primary annealing, cold rolling, and secondary annealing under specific conditions in that order to obtain an aluminum foil material of the required thickness.
The history of the plate material to be subjected to the first annealing before the first annealing is not particularly limited.

In other words, a plate material obtained by soaking and hot rolling an ingot obtained by semi-continuous casting or ingot casting according to a conventional method, or a plate material obtained by rough cold rolling after hot rolling,
Furthermore, a plate obtained by a molten metal direct rolling method (continuous casting and rolling method) or a plate obtained by rough cold rolling may be used.

Here, there is no need to particularly limit the soaking conditions when soaking and hot rolling an ingot obtained by half-solid casting or ingot casting. Soaking for ~48 hours is recommended.

For hot-rolled plates, cold-rolled plates, or molten metal directly rolled plates as described above, the heating temperature increase rate is 100°C/h.
The temperature is raised to a temperature range of 280 to 400 °C at a low temperature increase rate of r or less, and held in that temperature range for 0.5 to 48 hours.
Next, perform annealing. The purpose of this first annealing is to sufficiently precipitate Fe and Sl dissolved in solid solution in the Al plate material and to perform recrystallization.

The holding temperature (annealing temperature) in this first annealing is 280
If the temperature is lower than 400°C, recrystallization will not occur, and if the holding temperature is higher than 400°C, precipitation of Fe will be small, so the holding temperature was set within the range of 2'80 to 400°C. Furthermore, if the heating rate up to the holding temperature range exceeds 100°C/hr, the amount of Fe precipitated during heating will be small, and therefore the heating rate will be 100°C/hr.
°C/hr or less. Note that in order to sufficiently precipitate Fe, it is preferable to set the temperature increase rate to 50° C./hr or less. Furthermore, if the holding time in the above temperature range is less than 0.5 hours, the precipitation of Fe will be insufficient, while if the holding time is longer than 48 hours, the Fe precipitation will reach a saturated state, which will only be economically wasteful. be. Therefore, the retention time is 0.5-48
It was time.

Here, the primary annealing may be performed directly on the hot-rolled sheet or the molten metal directly rolled sheet as described above, but if the primary annealing is performed after cold rolling at a rolling ratio of 30% or more, ,
Recrystallized grains become finer.

In addition, since the precipitation of Fe is further promoted, it is preferable to cold-roll the hot-rolled sheet or the molten metal directly rolled sheet by 30% or more before performing the primary annealing.

After sufficiently precipitating and recrystallizing Fe1S1 through the primary annealing, cold rolling is performed at a rolling ratio of 50% or more, followed by 2
Secondary annealing is performed by rapidly heating to a temperature in the range of 80 to 425°C and holding in that temperature range for a short time of 10 minutes or less.

The main purpose of this secondary annealing is to make the recrystallized grains fine and uniform by rapidly heating the plate that has been subjected to cold rolling at a relatively high rolling rate of 50% or more to introduce strain. In addition, heating is performed at a relatively low temperature (280 to 425° C.) for a short time so as not to dissolve the Fe precipitated in the first annealing into a solid solution again (so as not to reduce the rollability).

Here, if the cold rolling ratio after the first annealing is less than 50%, the recrystallized grains in the second annealing will not become sufficiently small, so the rolling ratio of the cold rolling after the first annealing is 50%. That's all. In addition, the annealing temperature (holding temperature) in the second annealing is 28
At temperatures below 0°C, recrystallization will not occur if the holding time is within 10 minutes with rapid heating at 1°C/q or higher; on the other hand, if the temperature is held at temperatures above 425°C, Fe precipitated during the first annealing will rapidly dissolve into solid solution. However, since the foil rolling property decreases, the annealing retention rIAv! , is 2
It is necessary to keep the temperature within the range of 80 to 425°C. Furthermore, if the heating rate up to the holding temperature range is less than 1°C/atm, the effect of refining the recrystallized grains by rapid heating cannot be obtained, and furthermore, if the holding time in the temperature range exceeds 10 minutes, the recrystallized grains will become finer. Coarsening will begin. Therefore, the temperature increase rate in the second annealing was set to be 1° C./SE or more, and the holding time at 280 to 425° C. was set to within 10 minutes. Here, in order to obtain finer recrystallized grains, the heating temperature increase rate in the second annealing should be set to 5℃/
It is desirable that the holding time be 3 minutes or less.

In this way, heating at a slow heating rate allows the first stage to be heated for a relatively long time.
Next annealing is performed to sufficiently precipitate and recrystallize the solid IFe in the material plate, and then cold rolling is performed to introduce strain, followed by short-time secondary annealing by heating at a rapid temperature increase rate. By performing this, a fine recrystallized structure can be obtained without causing re-solid solution of precipitated Fe.

Furthermore, by performing the annealing and recrystallization twice, the crystal grain size can also be made uniform. Therefore, the aluminum foil substrate obtained by the above process has good foil rolling properties due to the small amount of solid solution Fe, has extremely few pinholes during foil rolling, and has fine and uniform crystal grains. Therefore, there is less occurrence of streak patterns during foil rolling, and there is also less roughness on the overlapping surfaces when foil rolling is performed by overlapping rolling.

The thickness of the foil fabric obtained as described above is usually 0.
The foil thickness is approximately 4 to 1 mm, and the foil rolling to this foil base is usually carried out until the foil thickness is approximately 0.05 to 0.054 mm. After rolling the foil, the rolling oil was heated to 300 to 500°C according to a conventional method in order to remove the rolling oil adhering to the surface of the foil and to soften the foil to improve handling and formability when the foil was used. ~2
Usually, the foil is annealed for about an hour.

Example 1 m of A1 alloy having two types of compositions shown in alloy codes A and B in Table 1 was manufactured according to a conventional method, and after casting, each ingot was
6. Soaking at 30°C for 12 hours and hot rolling. It was made into a plate material with a thickness of Osm, and was further cold rolled to a thickness of 3.01. The cold-open rolled sheets were subjected to heat treatments shown in Tables 1 to 14IIL18 in Tables 2 and 3. Here, Se1 to Na6. hiO ~ 15 is 3.0-thick and the first
Next annealing was performed, and at the stage of rough cold rolling to a thickness of 0.91 mm, second annealing was performed. Also Na7~Nl18
, Magnetics 16 to N117 were obtained by cold-rolling the cold-open rolled sheets of 3.0+n+ thickness to a thickness of 0.9+n without performing primary annealing, and annealing was performed only at that stage. Roughly Na9, m18 is obtained by further cold rolling the above 3,011-thick cold-open rolled plate to a thickness of 1.5-1, and at that stage the first
After the next annealing, cold rolling to 0.9-thickness (rolling rate 4
0%) and was subjected to secondary annealing. Each plate (annealed foil material) with a thickness of 0 and 9 mm thus obtained was further foil rolled to a thickness of 15JJI, and then
A foil with a thickness of 7JJI was obtained by lap rolling.

In the above examples, the crystal grain size of the foil material with a thickness of 0.91 after the secondary annealing was investigated, the tensile strength of each sample was investigated at the stage of 15 thicknesses, and the foil surface with the final value of 7JJII thickness was investigated. The results of investigating the condition of the streak pattern and the surface roughness of the overlapping surface (matte surface) during lap rolling are summarized in the second
They are also shown in Table and Table 3. The evaluation of the streak pattern was as follows: "O" indicates that the stripe pattern was not visible and the appearance was good, "Δ" indicates that the stripe pattern was slightly generated, and "X" indicates that the stripe pattern was noticeable and the product appearance was poor. I took it as a thing. In addition, for evaluation of roughness of the overlapped surface, marks of 0, Δ, and X were given in descending order of roughness.

Table 1: Chemical composition of sample materials (wt%) Table 2 Table 3 As is clear from Tables 2 and 3, when the method of the present invention was followed (samples NfL1 to N13, N11O to L
1kL12) have low tensile strength at 15JJI thickness, that is, low work hardening and good rollability, and have fine crystal grains at the 0.9am thick secondary annealing stage. Since it was uniform, it is clear that there was little streak pattern or roughness on the matte surface due to overlapping rolling.

Note that samples N14 and Na13 have a high annealing holding temperature of 450°C in the first annealing, and sample 81
6. Hidden 15 has a temperature increase rate of 400℃/in the first annealing.
hr, the precipitation of Fe is not sufficiently performed in either case, and as a result, the tensile strength at 15 tone thickness becomes high and the rolling properties deteriorate. In addition, in both samples Ha5 and N1114, since the holding temperature in the second annealing was as high as 450°C, the Fe precipitated in the first annealing was re-dissolved, and as a result, the tensile strength at a thickness of 15JJ+1 increased and the rolling In addition, the recrystallized grains became coarse during the second annealing, resulting in roughness of the matte surface. Furthermore, samples Na7 and kl 6 are 3
．． This is because annealing was not performed at 0II thickness, but only annealing was performed at the 0.9-thickness stage using body heat and holding for a long time.

The crystal grains were not finely divided, resulting in a streaky pattern and rough matte surface. Also, sample Na8.81117 is.

Because annealing was not performed at a thickness of 3.01, and only annealing was performed at the stage of 0.9++ue thickness by rapid heating and holding for a short time, sufficient precipitation of Fe was not achieved, and the tensile strength at a thickness of 15JJIl was high, resulting in a failure in rolling. It can be seen that the quality is decreasing.

Furthermore, although the conditions of the first annealing and the second annealing are within the scope of the present invention, samples NIL9, NQ, and 18 were not subjected to the second annealing because the rolling ratio of the cold rolling between them was low (40%). The recrystallized grains were not made sufficiently fine, and the matte surface became rough.

Effects of the Invention As is clear from the above examples, according to the method of the present invention, it is possible to produce an aluminum foil substrate with good foil rolling properties and fine and uniform crystal grains. When obtaining foil using the foil base produced by the method of the invention, it is possible to reduce the occurrence of pinholes during foil rolling, and at the same time, it is possible to reduce the appearance defects due to the occurrence of streaks during foil rolling, and to reduce the occurrence of overlapping rolling. It is also possible to reduce the occurrence of roughness on the overlapping surface (matte surface) during processing, and it is therefore possible to obtain aluminum foil of extremely high quality as a packaging material, etc.

Applicant Sky Aluminum Co., Ltd. Agent Patent Attorney Yutaka 1) Hisashi Take (line or 1 person)

Claims (1)

[Claims] Weight ratio: Fe0.1-0.8%, Ti0.003-0.
1%, and contains 0.50% or less of Si as impurities, 0.10% or less of Cu, 0.10% or less of Mn, M
g to 0.05% or less, and the balance is Al and other unavoidable impurities.
Heat to a temperature within the range of °C and reduce the temperature within that range by 0.5 °C.
First annealing is performed for ~48 hours, followed by cold rolling at a rolling reduction of 50% or more, and then heated to a temperature within the range of 280 to 425°C at a temperature increase rate of 1°C/sec or more. A method for producing an aluminum foil substrate, which comprises performing secondary annealing by holding the temperature within a range for a short time of 10 minutes or less.