JP2003164903A - Method for manufacturing aluminium foil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing aluminium foil with good rolling property in a foil rolling mill, which reduces the generation of pinholes in high-speed foil rolling as well as the generation of macro stripes of the foil. <P>SOLUTION: An aluminium alloy ingot, containing Fe of 0.20-0.80%, Si of 0.05-0.30%, Cu of 0.003-0.10% and Mg of 0.01% or less with Fe/Si ratio of 2-10, and containing one kinds or more of Ti of 0.005-0.2% and B of 0.0001-0.005%, after undergoing the soaking at 500°C or higher, starts to be hot-rolled at 360-460°C. In the rough hot-rolling at the stage of the plate thickness of 10-100 mm, at least one pass is carried out with the rate of descent of 50-85% and the distortion speed of 2/sec or more, at the temperature of 340-420°C. The temperature of the finishing hot-rolling is set at 200-330°C. After the hot-rolling, the primary cold rolling is carried out at the rolling rate of 50% or more, and then the batch annealing is carried out at 250-450°C maintained for more than 0.5 hours. Thereafter the secondary cold rolling is carried out. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aluminum foil, and more particularly, the rollability is good in a foil rolling mill and pinholes are generated by high-speed foil rolling. The present invention relates to a method for manufacturing an aluminum foil having a small amount of macro streaks. [0002] Aluminum foil has a thickness of about 5 to 200 μm and is mainly used for packaging foodstuffs, medicines, etc., and is used by being bonded to polyethylene, vinyl, paper, resin, etc. Often done. Conventionally, aluminum foils for such applications include JIS-1N30, J
Pure aluminum alloys such as IS-1050 and JIS-1100 are generally used, casting ingots from molten aluminum by a semi-continuous casting method, homogenizing treatment,
A plate material having a thickness of about 0.4 to 2.0 mm by hot rolling and cold rolling, then subjected to intermediate annealing, and further a plate material having a thickness of about 0.15 to 0.60 mm by cold rolling.
It is a common manufacturing method to form (foil), then foil-roll to a thickness of about 5 to 200 μm by foil rolling, and further anneal. Note that the above-described homogenization treatment, intermediate annealing, and the like may be omitted depending on the required levels of quality and cost. As described above, aluminum foil is used for packaging foodstuffs, medicines, etc., and aluminum foil used for such applications is:
The function of shielding the contents from atmospheric moisture and ultraviolet rays becomes important. However, a minute hole called a pinhole is generated in the manufacturing process of the foil, and if the number of the pinhole is large, the quality of the contents may be deteriorated by the outside air or light entering from the pinhole. For this reason, how to reduce pinholes is an important issue in foil production. In recent years, in order to increase productivity, higher-speed foil rolling has been performed, and accompanying this, the occurrence of pinholes, especially the increase in the occurrence of pinholes in thin foils with a thickness of 15 μm or less has become a problem. ing.
An object of the present invention is to provide a foil having less pinholes even when a thin foil having a thickness of 15 μm or less is produced by high-speed foil rolling. As a result of the inventor's repeated experiments and studies to solve the above-described problems, the alloy composition is appropriately selected, and at the same time, during the plate manufacturing process, Appropriate combination of manufacturing processes such as homogenization, hot rolling, cold rolling, and intermediate annealing, and in particular, by controlling the recrystallization behavior of the material during hot rolling, the problem described above can be solved. The headline and the present invention were made. Specifically, as described in claim 1, Fe:
0.20 to 0.80%, Si: 0.05 to 0.30%,
Cu: 0.003 to 0.1%, Mg: 0.01% or less, satisfying the relationship of Fe / Si = 2 to 10, and T
i: 0.005-0.2, B: 0.0001-0.05
1 type or 2 types selected from among them, with the balance being A
1 and an alloy consisting of inevitable impurities is made into an ingot.
After performing homogenization at a temperature of 00 ° C. or higher, 360 ° C. to
Hot rolling is started at a temperature range of 460 ° C.
At least once in hot rough rolling in the 00mm stage
Pass reduction ratio of 50% to 85%, distortion rate at this time is 2
/ Sec or more, the temperature is set to 340 to 420 ° C., the hot temperature of the hot finish rolling is set to 200 to 330 ° C., and then the primary cold rolling is performed at a rolling rate of 50% or more. Al- with less macro streak, characterized by performing batch annealing at 250 to 450 ° C. and holding for 0.5 h or more, followed by secondary cold rolling, and low pinholes even when high speed foil rolling is performed It is a manufacturing method of Fe-type foil. DETAILED DESCRIPTION OF THE INVENTION The present inventors have described 10 to 10 in the hot rolling stage.
If recrystallization is insufficient at a thickness of 100 mm, strong macro streaks are formed on the hot-rolled sheet, and if such a plate with strong macro streaks is subjected to intermediate annealing, coarse crystal grains corresponding to the macro streaks are formed. It has been found that such a remarkably non-uniform grain structure is inferior in pinhole resistance. The present invention provides a method for suppressing such macro streak and providing a foil with less pinholes. First, the reasons for limiting the alloy component composition of the present invention will be described. Fe: Fe is an alloying element which is a basic element of the present invention, and is an important element that forms an intermetallic compound with Al or Al and Si and contributes to refinement of crystal grains and improvement of strength. In the present invention, by adding a large amount of 0.20 to 0.80%, the solid solution and precipitation of Fe, the size and distribution of intermetallic compounds are controlled, and a large amount of Fe-based intermetallic compounds are dispersed in the matrix. To increase the number of nucleation sites for recrystallization.
It improves pinhole resistance. Fe amount is 0.
If it is less than 2%, it is difficult to refine the crystal grains. Conversely, 0.8
If it exceeds 50%, the foil rollability is inferior. Si: Si is an alloy element which is the basis of the present invention, and forms an intermetallic compound with Al.Fe and contributes to refinement of crystal grains. Moreover, Si accelerates the precipitation of Fe and affects the recrystallization behavior. Si amount is 0.05%
If it is less than 1, precipitation of Fe becomes insufficient, recrystallization that occurs during hot rolling is delayed, and macro streaks are likely to be formed. On the other hand, if it exceeds 0.3%, the amount of Si is too much and pinhole resistance is lowered. If the ratio Fe / Si of Fe / SiFe to Si is less than 2, a fine recrystallized grain structure may not be obtained, and if it exceeds 10, foil rolling becomes difficult and pinholes are likely to occur. There is a problem. Therefore, Fe / Si is set to a range of 2 to 10. Cu: Cu is an alloying element that is the basis of the present invention, and is an important element for improving strength and preventing material softening during foil rolling. However, if it is 0.003% or less, there is no effect of preventing material softening, and if it exceeds 0.1%,
Work hardening is easy to proceed and pinhole resistance decreases. Mg: Mg has the effect of reducing the adhesion between the foil and the resin / vinyl even if contained in a small amount.
It is necessary to regulate to 0.01% or less. Ti, B: In a normal aluminum alloy, a small amount of Ti or Ti and B is added for refining ingot crystal grains. In this invention, a small amount of Ti or Ti is also added. And B are added. However, if the amount of Ti is less than 0.005%, the effect cannot be obtained, and if it exceeds 0.20%, a huge Al—Ti intermetallic compound is crystallized and pinhole resistance is lowered.
The amount was in the range of 0.005 to 0.20%. Moreover, if B is added together with Ti, the effect of ingot crystal grain refinement is improved. However, when adding B together with Ti, the amount of B is 0.0.
If it is less than 001%, the effect is not obtained, and if it exceeds 0.05%, Ti-B coarse particles are mixed and the pinhole resistance is deteriorated. Therefore, B is set in the range of 0.0001 to 0.05%. . If other impurity elements such as Mn, Cr, Zn, Zr, and V are restricted to 0.05 or less, the effect of the present invention is not hindered. Next, the manufacturing process will be described. The present inventors have found that the crystal grain size during the intermediate annealing is closely related to the hot rolling process. That is, 1 in the hot rolling stage
If recrystallization is insufficient at 0-100 mm plate thickness,
Strong macro streaks are formed on the hot-rolled sheet. If such a plate with strong macro streak is subjected to intermediate annealing, coarse crystal grains may be generated corresponding to the macro streak, and such extremely uneven crystal grain structure is inferior in pinhole resistance. There was found. Therefore, the manufacturing conditions are defined as follows. Homogenization treatment: Homogenization treatment not only eliminates the segregation of elements generated during casting, but also adjusts the solid solution and precipitation of Fe and Si and the size and distribution of these intermetallic compounds, thereby preventing pinhole resistance. It is effective in improving. However, 500
If it is less than 0 ° C., the above effect is insufficient. Further, the upper limit is not particularly limited, but a temperature range in which eutectic melting does not normally occur 6
It shall be 30 degrees C or less. Hot rolling conditions: Hot rolling is an important process for mechanical properties, surface quality, and pinhole resistance, and it is essential to limit the conditions to a specific range. When the hot rolling start temperature is lower than 360 ° C., recrystallization during hot rolling is suppressed, macro streaks are easily formed, and pinhole resistance is deteriorated. On the other hand, when hot rolling is started at a temperature exceeding 460 ° C., the crystal grains formed during hot rolling become large and pinhole resistance is reduced. Therefore 360-46
Control within the range of 0 ° C. Furthermore, in order to improve pinhole resistance and reduce macro streak, during hot rolling, especially 10m
In hot rough rolling with a thickness of m to 100 mm, it is important to cause fine recrystallization. Therefore, it is indispensable to appropriately control the reduction ratio, strain rate, temperature, and the like at this stage. If the rolling reduction is less than 50%, it is difficult to obtain fine recrystallized grains. On the other hand, if it exceeds 85%, the rolling load is large and the surface quality is deteriorated. Therefore, the rolling reduction for one pass is 50 to 85%. If the strain rate at this time is less than 2 / sec, it is difficult to obtain fine recrystallized grains. Accordingly, the strain rate is 2 / sec or more. Although the upper limit is not restricted, it is usually 20 /
Control to less than sec. If the temperature is lower than 340 ° C., the recrystallization proceeds insufficiently and macro streaks are likely to be formed. on the other hand,
If it exceeds 420 ° C., it is difficult to obtain fine crystal grains. Therefore, it is necessary to make it the temperature range of 340-420 degreeC. If the hot rolling end temperature exceeds 330 ° C., non-uniform coarse crystal grains may be formed. If it is less than 200 ° C., lubrication failure or water corrosion may occur.
It was set as the range of -330 degreeC. Primary cold rolling before intermediate annealing: A cold rolling rate of 50% or more is necessary to obtain fine crystal grains during intermediate annealing. If it is less than 50%, cold strain accumulation is insufficient, crystal grains during intermediate annealing tend to be coarse, and pinhole resistance is lowered. Intermediate annealing conditions: The material is completely recrystallized,
It is an indispensable process for improving pinhole resistance by adjusting appropriate material strength and promoting precipitation of Fe and Si. Intermediate annealing is performed in a batch furnace. If it is less than 250 ° C., recrystallization hardly proceeds and it takes too much time until complete recrystallization occurs, resulting in an increase in cost. Conversely, at temperatures above 450 ° C,
In addition to coarsening of the crystal grains, a thick surface oxide film may be formed, which may reduce the adhesion to the coating film / film. In order to suppress the formation of an oxide film, annealing at a temperature of 430 ° C. or lower and in an inert gas atmosphere is preferable. If the treatment time is less than 0.5 h, a uniform recrystallized structure may not be obtained. Although the upper limit of the holding time is not regulated, it is usually within 24 hours in consideration of economy. Thereafter, secondary cold rolling is performed to obtain a foil. And this foil is rolled into a foil product. The foil obtained as described above has a final foil rolling speed (final pass) of 40 as well as general foil rolling.
Thin thickness of 5.5 to 7 by high speed foil rolling at 0 mpm or more.
Even under the harsh conditions of rolling to a thin foil of 0 μm,
The foil is excellent in pinhole resistance and can provide a foil with less pinholes. EXAMPLE Alloys A1 to A3 within the composition range of the present invention shown in Table 1 and alloys with alloy code B1 outside the composition range of the present invention are cast by DC casting according to conventional methods. After the homogenization treatment was performed on the resulting ingot, hot rolling was started, followed by cold rolling, intermediate annealing in the middle of the batch, and cold rolling to obtain a foil. It was. Detailed conditions are shown in Tables 2 and 3. [Table 1] [Table 2] [Table 3] The foil obtained as described above was visually checked for the presence of macro streaks. In addition, the thing which does not see a macro streak was made "good". Further, the foil was rolled to each thickness shown in Table 4, and the number of pinholes was examined by visual observation in the dark about the obtained foil. The results are shown in Table 4. [Table 4] 1, 2 and 3 are the alloy components of the present invention and the production method of the present invention. Each of 1, 2 and 3 has a weak macro streak, an extremely small number of pinholes, and good pinhole resistance. is there. On the other hand, 4 is an alloy component of the present invention, but the manufacturing conditions are out of the scope of the present invention, and 10 to 100 mm.
In rough hot rolling at the plate thickness stage, the one-pass rolling reduction was small and the material temperature was low, so the macro streaks were strong and the number of pinholes was large. In addition, although the production method 5 is within the scope of the present invention, since the alloy component is high in Cu content and deviates from the scope of the present invention, the pinhole resistance is poor even when the method of the present invention is used. As described above, the foil according to the present invention is less likely to have pinholes when it is rolled to a thickness of 15 μm or less, especially when it is rolled at high speed by a high speed foil rolling machine. Therefore, even when used for food packaging or the like, it exhibits a high barrier property.

Front page continuation (51) Int.Cl. ⁷ Identification symbol FI Theme code (reference) C22F 1/00 682 C22F 1/00 682 683 683 686 686A 691 691B 694 694A 694B

Claims (1)

Claims: 1. Fe: 0.20-0.80%, Si:
0.05 to 0.30%, Cu: 0.003 to 0.1%,
Mg: 0.01% or less, satisfying the relationship of Fe / Si = 2 to 10, Ti: 0.005 to 0.2, B:
An alloy containing one or two selected from 0.0001 to 0.05, with the balance being Al and inevitable impurities, was ingot, and homogenized at a temperature of 500 ° C. or higher. Thereafter, hot rolling is started in a temperature range of 360 ° C. to 460 ° C., and the rolling reduction of one pass is 50% to 85 at least once in the hot rough rolling at a thickness of 10 to 100 mm.
%, The strain rate at this time is 2 / sec or more, and the temperature is 340
˜420 ° C., and the finishing temperature of hot finish rolling is 200 to 3
Hot rolling was performed at 30 ° C., and then primary cold rolling was performed at a rolling rate of 50% or more, and intermediate annealing was performed at 250 to 450 ° C.
Al-Fe with few macro streaks, characterized by batch annealing for 0.5 h or more, followed by secondary cold rolling, and low pinholes even at high speed foil rolling
A manufacturing method of a foil-based fabric.