JPH04124251A - Production of aluminum foil - Google Patents

Abstract

PURPOSE:To improve strength and formability and to reduce pinholes in a foil by subjecting an Fe-containing Al alloy to hot rolling and to annealing, cold-rolling the resulting plate while process-annealing it between the cold rolling stages, applying cold rolling to the resulting sheet at high draft, and then exerting finish annealing at low temp. CONSTITUTION:An Al alloy containing 0.7-2.0wt.% Fe is hot-rolled and annealed at 350-500 deg.C. In the course of successive cold rolling, process annealing is exerted at the time when a sheet thickness of >=50% draft is reached, and further, the resulting sheet is rolled at >=90% draft to the thickness of a foil product. Successively, finish annealing treatment is performed at 200-300 deg.C. By this method, the occurrence of strain at the time of annealing can be prevented and the abnormal growth of crystalline grains can be prevented. Further, adhesive strength between the foil and a laminate can be improved, and a laminated product excellent in corrosion resistance can be obtained.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing aluminum foil that has excellent strength and formability and has few pinholes. (Prior Art and Problems to Be Solved) Generally, aluminum foil is used with a thickness in the range of about 5.degree. 5 to 100 .mu.m depending on the purpose. Conventionally, aluminum foil is generally lN30 (JI
Pure aluminum (S 84160) has been used, but in recent years, aluminum foil such as 8011.8o79 has been used for packaging aluminum foil that requires forming.
2-Fe alloy and 8006 with Mn added in addition to Fe
Other alloys are also being used. In addition, recently, there has been a trend towards thinner walls due to the desire to reduce costs, but the thinner the aluminum foil, the more pinholes will increase exponentially, and the barrier properties against moisture and air, which are the characteristics of aluminum foil, will deteriorate, making it difficult to use. This poses a problem. Therefore, in order to reduce pinholes, the manufacturing process of foil fabrics has been studied (Japanese Patent Publication No. 60-56786, Japanese Patent Application Laid-Open No. 63-18041, etc.), and the above AM-Fe alloy,
Using Al-Fe-Mn alloy for thin foil of 15 μm or less,
Attempts have been made to produce aluminum foil that has excellent formability, strength, and pinhole resistance (Japanese Patent Laid-Open No. 63-263
No. 22). However, when manufacturing thin-walled can products using the above-mentioned AQ-Fa gold alloy, there are the following problems. (2) The degree of solid solution of Fe, which is an alloying element, has a large effect on the softening behavior during final annealing, which may lead to variations in the strength and formability of aluminum foil products. That is, if the amount of solid solution of Fe is large, the softening temperature will be high, resulting in insufficient softening during production, which may result in insufficient moldability. ■Furthermore, in order to sufficiently promote softening, final annealing is sometimes carried out at a high temperature of 300°C or higher, but this may cause shape distortion, coarsening of crystal grains, and increased oxidation during this annealing. Decreased adhesion of laminated foil due to
This may cause deterioration of product quality. Therefore, it is currently desired to develop a material that softens at a finish annealing temperature as low as possible. The present invention has been made in response to the above-mentioned demands, and an object of the present invention is to provide a method for manufacturing Aluminum 11 foil that can improve the quality of the tube by lowering the final annealing temperature. It is. (Means for Solving the Problems) In order to solve the above problems, the present inventor has conducted extensive research and has discovered that it is possible to solve the problems by specifying the composition of the aluminum foil and the manufacturing process and conditions. It is. That is, in the present invention, an aluminum alloy containing 0.7 to 2.0 wt% of Fe and the balance consisting of Al and unavoidable impurities is annealed in a temperature range of 350 to 500 ° C. after hot rolling. During the cold rolling process, the processing rate is 50
% or more, intermediate annealing is performed when the plate thickness is 20% or more, and after rolling with a processing rate of 90% or more to obtain a can product thickness, final annealing is performed at 20% or more.
The gist of the present invention is a method for producing aluminum foil, which is characterized in that it is carried out at a temperature range of 0 to 300°C. The present invention will be explained in more detail below. (Function) First, in the present invention, Al-Fe (0.7 to 2.0vt%
) using alloys. Addition of Fe is most effective in refining crystal grains and is effective in improving strength and formability. Here, if the Fe content is less than 0.7 tit%, grain refinement will be insufficient, and there will be no effect on improving strength, formability, and reducing pinholes. Also, 2. Ot
If it exceeds gt%, the effect will be saturated and the huge AQ-Fe-based intermetallic compound will be difficult to split in the subsequent cold rolling process and will tend to remain, resulting in poor formability and the formation of pinholes. bring about negative effects. In addition,
Addition of a third element such as Mn should be avoided because the characteristics tend to change due to fluctuations in manufacturing process conditions. Furthermore, in the present invention, since the characteristics of the aluminum alloy are easily changed depending on manufacturing conditions, manufacturing process control is required as described below. That is, after hot rolling, annealing is performed in a temperature range of 350 to 500°C. This is in order to homogenize the structure by controlling fluctuations in solid solution and precipitation of Fe due to temperature history during hot rolling, and by performing this heat treatment, recrystallization is performed and precipitation of Fe is promoted. To recrystallize 3
A temperature of 50° C. or higher is required, but if the temperature exceeds 500° C., solid solution of the Fe element will not only proceed, but also the recrystallized grains will become coarser, resulting in poor quality and a waste of energy. After annealing, cold rolling including intermediate annealing is performed, but first, it is necessary to increase the cold working rate up to intermediate annealing. In other words, by increasing the cold working rate up to intermediate annealing, it is necessary to change the recrystallized structure in coarse annealing to a fine worked structure, and to promote precipitation during intermediate annealing, it is necessary to accumulate working strain. Therefore, the cold working rate is set to 5.
0% or more. After intermediate annealing, the cold working rate is set at a high rate of 90% or more. This is to refine the recrystallized structure after intermediate annealing by strong working, and to refine the recrystallized structure in the can product after final annealing. If it is less than 90%, the recrystallized grains in the foil product after finish annealing will become large, resulting in poor strength and formability, and will cause roughness of the matte surface during double ring rolling during finish rolling of the foil, resulting in pinholes. will increase. Preferably it is 95% or more. Next, finish annealing is performed, and the finish annealing temperature is 200
It may be in the range of ~280°C. Conventionally, finish annealing was performed at a temperature of 300° C. or higher, but in the present invention, by using the steps and conditions described above, the treatment can be performed at a lower temperature. If finish annealing is performed at a high temperature exceeding 280°C, shape distortion, increase in oxide film, and increase in crystal grains are likely to occur during annealing. Therefore, finish annealing is performed at a temperature below 280°C, but re-annealing is not possible below 200°C. The temperature range is set at 200° C. to 280° C. since this may lead to insufficient crystallization and poor moldability. Preferably it is 220-260°C. Examples of the present invention are shown below. (Example) Al-Fe alloys containing various Fe contents shown in Table 1 are formed into ingots by a conventional method, and hot-rolled into hot-rolled sheets (3, Om+m).
After manufacturing, successively, rough annealing, cold rolling (including intermediate annealing) and finish annealing were performed under the conditions shown in Table 1. The results of investigating the material properties (number of pinballs, strength, elongation, crystal grain size, oxidation and film thickness, etc.) of the obtained can products are also listed in Table 1. In addition, at the time of foil finish rolling, double ring (overlapping) rolling was performed to obtain a foil with a thickness of 7 μm. The number of pinholes was determined by shining light from below the foil in a dark room, counting the number of pinholes visually, and then converting the number to the number per 1n+2. The crystal grain size was observed using an optical microscope and the average grain size was measured. Regarding strength and elongation, tension and total elongation were measured using an Instron tensile tester. Tensile test piece is 15m wide
A strip-shaped louse with an effective length of 100 mm was used. From Table 1, it can be seen that in all of the examples of the present invention, high-quality can products with excellent strength and elongation and a small number of pinholes were obtained.

[Left below]

(Effects of the Invention) As detailed above, according to the present invention, the following excellent effects can be obtained. ■Since the final annealing temperature can be set at a low temperature, it is possible to prevent the occurrence of distortion during annealing, and also to suppress abnormal growth of crystal grains, resulting in can products with excellent mechanical properties and distorted shapes. Furthermore, since the growth of the oxide film during annealing can be suppressed, the adhesion between the foil and the laminate is improved, and a laminate product with excellent corrosion resistance can be obtained. Moreover, it is advantageous in terms of thermal energy, and productivity can be improved. ■Even with thin and thick foils, excellent strength and elongation can be obtained, and the occurrence of pinholes can be suppressed. It will be possible to make the wall thinner than the current one, which will reduce costs. ■In addition to suppressing quality variations due to temperature and time fluctuations during hot rolling, unlike conventional aluminum alloys, no third elements other than Fe (Mn, etc.) are added, so it is less affected by other manufacturing conditions. This makes it possible to stabilize the quality.

Claims (1)

[Claims] For an aluminum alloy containing 0.7 to 2.0 wt% of Fe and the balance consisting of Al and unavoidable impurities, after hot rolling and annealing in a temperature range of 350 to 500 ° C.,
During the cold rolling process, intermediate annealing is performed when the thickness of the plate is at a processing rate of 50% or more, and after further rolling with a processing rate of 90% or more to achieve the thickness of the foil product, final annealing is performed at a temperature range of 200 to 300 ° C. A method for producing aluminum foil, characterized in that the method is carried out.