JP2020063482A - Aluminum alloy foil for electromagnetic cooking vessel and aluminum foil-molded container - Google Patents

Abstract

To provide an aluminum alloy foil for an electromagnetic cooking vessel that is suitable for electromagnetic cooking and has excellent corrosion resistance and moldability, and an aluminum foil-molded container.SOLUTION: An aluminum alloy foil for an electromagnetic cooking vessel has a composition containing Si: 0.1 wt.% or less, Fe: 0.21-0.40 wt.%, Cu: 0.006-0.01 wt.%, Mn: 0.5-3.0 wt.%, Mg: 0.5-2.0 wt.%, Cr: 0.05 wt.% or less, Zn:0.05-0.50 wt.% with the balance being Al and unavoidable impurities, preferably, with a foil thickness of 65-150 μm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an aluminum alloy foil for an electromagnetic cooking container and an aluminum foil forming container that can be used for electromagnetic cooking.

Aluminum alloy foil is widely used as a container for heated food such as noodles and pans because it has excellent formability and thermal conductivity and is lightweight, and it is also requested to be applied to heating using an electromagnetic cooker. Has been done.
Therefore, the aluminum alloy foil is required to have good heating efficiency (hereinafter referred to as IH proper) for electromagnetic cooking. Further, since it is distributed in the state of containing food for cooking and the like, it is required to have excellent corrosion resistance.

  For example, Patent Document 1 provides an aluminum alloy foil forming container having excellent formability and corrosion resistance by using an aluminum alloy foil having a specific thickness and a specific electric resistance value.

International Publication No. 2009-41428

  The aluminum alloy foil has few impurity elements and the higher the purity, the higher the corrosion resistance. The aluminum foil is molded into a container shape, but heat treatment using the aluminum foil as a soft foil is performed so that the aluminum foil can be easily processed. However, in a high-purity aluminum alloy foil, the grain size after the final annealing increases due to the heat treatment, and the formability decreases. Also, the higher the purity, the higher the cost of metal. It is required to achieve both corrosion resistance and moldability at the same time and to produce at low cost.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an aluminum alloy foil for an electromagnetic cooking container and an aluminum foil molded container which have an excellent balance of corrosion resistance and formability and are suitable for electromagnetic cooking.

That is, in the aluminum alloy foil for an electromagnetic cooking container of the present invention, the first form is Si: 0.1 wt% or less, Fe: 0.21 to 0.40 wt%, Cu: 0.006 to 0.01 wt%, Mn: 0.5 to 3.0 wt%, Mg: 0.5 to 2.0 wt%, Cr: 0.05 wt% or less, Zn: 0.05 to 0.50 wt%, with the balance Al and unavoidable impurities It has a composition consisting of

  Another form of the aluminum alloy foil for an electromagnetic cooking container according to the above-mentioned form of the invention is that the foil thickness is 65 to 150 μm.

  Another form of the aluminum alloy foil for an electromagnetic cooking container according to the invention of the above form is characterized in that the average crystal grain size is in the range of more than 20 μm to 100 μm.

  The aluminum foil molding container of the present invention is characterized by using the aluminum alloy foil for an electromagnetic cooking container according to any one of the above-mentioned aspects.

Hereinafter, the reasons for specifying the components and the like specified in the present invention and their actions will be described.
Si: 0.1 wt% or less, preferably 0.01 to 0.05 wt%
Si is included because it promotes the precipitation of Mn crystals and refines the crystal grains. However, if the Si content exceeds 0.1 wt%, Mn is excessively crystallized, the IH suitability is lowered, and the corrosion resistance is lowered. For the same reason, it is desirable to set the upper limit to 0.05 wt.
If the Si content is less than 0.01 wt%, the above-mentioned effects cannot be sufficiently obtained, and the purity is high and the cost increases, so the lower limit is preferably 0.01 wt%.

Fe: 0.21 to 0.40 wt%, preferably 0.25 to 0.30 wt%
Fe is contained because it promotes the precipitation of Mn crystals and refines the crystal grains. When the Fe content is less than 0.21 wt%, the above-described action cannot be sufficiently obtained, and the purity is high and the cost is increased. Further, the crystal grain size after the final annealing becomes coarse, and the formability decreases. On the other hand, when the Fe content exceeds 0.40 wt%, the corrosion resistance decreases. For the same reason, it is desirable that the Fe content has a lower limit of 0.25 wt% and an upper limit of 0.30 wt%.

-Cu: 0.006-0.01 wt%, preferably 0.006-0.008 wt%
A small amount of Cu has the effect of increasing the strength, but reduces the corrosion resistance. If the Cu content is less than 0.006 wt%, the purity is high and the cost is increased. On the other hand, if the Cu content exceeds 0.01 wt%, the corrosion resistance decreases, so the content is limited to 0.01 wt% or less. For the same reason, it is desirable to set the upper limit to 0.008 wt%.

Mn: 0.5 wt% to 3.0 wt%, preferably 1.0 to 2.0 wt%
Mn is contained because it has the effect of increasing the electrical resistivity. If the Mn content is less than 0.5 wt%, sufficient electrical resistivity cannot be obtained. In addition, the strength is reduced. On the other hand, if the Mn content exceeds 3.0 wt%, a coarse intermetallic compound crystallizes and the formability deteriorates. In addition, the amount of heat for sufficient recrystallization is large, and the formability deteriorates due to insufficient recrystallization during the final annealing. For the same reason, it is desirable that the lower limit of the Mn content is 1.0 wt% and the upper limit thereof is 2.0 wt%.

-Mg: 0.5 wt% to 2.0 wt%, preferably 0.7 to 1.7 wt%
Mg is contained because it has the effect of increasing the electrical resistivity. If the Mg content is less than 0.5 wt%, sufficient electrical resistivity cannot be obtained. In addition, the strength is reduced. On the other hand, when the Mg content exceeds 2.0 wt%, the strength becomes too high and the formability deteriorates. For the same reason, it is desirable that the lower limit of the Mg content is 0.7 wt% and the upper limit thereof is 1.7 wt%.

-Cr: 0.05 wt% or less, desirably 0.01 to 0.03%
Cr is contained because it has the effect of increasing the electrical resistivity. However, if the Cr content exceeds 0.05 wt%, the amount of heat for sufficient recrystallization is large, and the formability deteriorates due to insufficient recrystallization during the final annealing. For the same reason, the Cr content is more preferably 0.03% or less.
Further, if the Cr content is less than 0.01 wt%, sufficient electrical resistivity cannot be obtained, so the lower limit is preferably made 0.01%.

-Zn: 0.05 wt% to 0.50 wt%, preferably 0.20 to 0.40 wt%
Zn has the effect of suppressing pitting corrosion. Further, since it can impart antibacterial properties, it is included. If the Zn content is less than 0.05 wt%, sufficient pitting corrosion inhibiting effect and antibacterial property cannot be obtained. On the other hand, if it exceeds 0.50 wt%, the corrosion resistance against general corrosion decreases. For the same reason, it is desirable that the Zn content has a lower limit of 0.20 wt% and an upper limit of 0.40 wt%.

・ Average crystal grain size: more than 20 μm to 100 μm
If the average crystal grain size exceeds 100 μm, the formability is reduced. On the other hand, when the average crystal grain size is 20 μm or less, the crystal grains are too fine and the 0.2% proof stress becomes too high, resulting in deterioration of formability.
Therefore, the average crystal grain size is preferably within the above range.
The average crystal grain size is more preferably more than 30 μm.

・ Foil thickness: 65 to 150 μm
By reducing the foil thickness, the electrical resistivity can be increased. However, if the foil thickness is less than 65 μm, sufficient strength cannot be obtained, and pinhole defects starting from the intermetallic compound may occur. On the other hand, if the foil thickness exceeds 150 μm, sufficient electrical resistivity cannot be obtained. In addition, moldability is deteriorated. For these reasons, it is desirable that the foil thickness of the aluminum alloy foil be within the above range. For the same reason, it is desirable that the foil thickness has a lower limit of 80 μm and an upper limit of 100 μm.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in corrosion resistance and moldability, has high electric specific resistance, and the effect suitable for electromagnetic cooking is acquired.

It is a perspective view showing the aluminum foil molding container of one embodiment of the present invention.

An embodiment of the present invention will be described below.
In manufacturing the aluminum foil container of the present invention, Si: 0.1 wt% or less, Fe: 0.21 to 0.40 wt%, Cu: 0.006 to 0.01 wt%, Mn: 0.5 to 3.0 wt% , Mg: 0.5 to 2.0 wt%, Cr: 0.05 wt% or less, Zn: 0.05 to 0.50 wt%, and the balance is Al.

The present invention is not limited to a particular method for producing an aluminum alloy, and can be produced by a desired method such as a semi-continuous casting method or a continuous casting method. Although the cooling rate of the casting is not particularly limited, the larger the cooling rate of the casting is, the higher the solid solution amount of the elements and the higher the electrical resistivity, but the surface segregation or the center line segregation of the aluminum alloy foil produced. Formability and corrosion resistance may be adversely affected. On the other hand, if the cooling rate is too low, the solid solution amount of the element decreases, and the required electrical resistivity cannot be obtained. For these reasons, it is desirable that the lower limit of the cooling rate be 100 ° C./s and the upper limit thereof be 1000 ° C./s. However, the present invention is not limited to the cooling rate within a specific range.
The obtained material may be homogenized if necessary. The homogenization treatment can be performed, for example, at 500 ° C. to 600 ° C. for 3 hours to 20 hours.

  The material after the homogenization treatment is hot-rolled to a desired thickness, and then cold-rolled, intermediate-annealed, and cold-rolled again to obtain an aluminum alloy foil having a desired thickness. it can. The foil thickness is not particularly limited, but is preferably 65 to 100 μm from the viewpoint of strength and electric resistance. Then, through the final annealing, the aluminum alloy foil of the present invention can be obtained. The conditions of the final annealing are preferably a temperature of 350 ° C. or higher and a holding time of 5 minutes or less. However, the present invention is not limited to this condition.

  By molding the above aluminum alloy foil, the aluminum alloy foil molding container of the present invention can be obtained. Molding can be performed by press molding or the like, and the shape of the molding container is not particularly limited. The aluminum alloy foil molded container for cooking can be provided.

For example, a wrinkled aluminum foil molded container 1 having a wrapping side wall 2 and a bottom portion 3 and having wrapping on the wrapping side wall 2 is obtained by drawing. It should be noted that the present invention may be one in which the circumferential side wall does not have wrinkles.
A convex shape having an outer peripheral surface shape along the inner surface of the wrinkled aluminum foil molded container 1 and having outer curved surfaces and inner curved surfaces that are alternately continuous in multiple stages is prepared on the outer peripheral surface, The outer peripheral surface of the convex shape can be transferred to the peripheral side wall 2 by fitting the aluminum foil molding container 10 in the opened state into the convex shape and clamping from the outer peripheral side.

  The obtained aluminum alloy foil molded container has high electric resistance and high IH suitability, and is suitable for heating in an electromagnetic cooker. Further, this molding container is not limited to electromagnetic cooking, but can be used for heating cooking by direct flame such as a gas stove.

-Manufacturing method After preparing a molten metal having the composition shown in Table 1 (the balance being Al and other unavoidable impurities), the aluminum alloy cast to a thickness of 10 mm at the cooling rate shown in Table 1 was subjected to cold rolling to obtain Table 1 After having the described thickness, final annealing was carried out at 400 ° C. for a heating and holding time of 5 minutes to obtain an aluminum alloy soft foil. The obtained aluminum alloy soft foil was evaluated for discoloration, average crystal grain size, formability, IH suitability, and corrosion resistance by the following methods, and the evaluation results are shown in Table 1.

<Evaluation method>
-Discoloration The difference in color tone of the aluminum alloy foil before and after the final annealing was visually determined. If there was no difference in color tone before and after the final annealing, it was judged as "○", if part or all of the surface was slightly discolored, it was "△", and if part or all was clearly yellowed, it was judged as "x". . If the evaluation is Δ or more, there is no problem in practical use, but it is desirable that the evaluation is ○.

-Average crystal grain size The average crystal grain size is the average of the minor axis and the major axis of each 100 crystal grains from the surface texture photograph taken with an optical microscope (magnification 100 times). The average value was calculated as the average particle size.

Moldability 1000 aluminum alloy foils were press-molded to produce 1000 aluminum alloy foil molding containers (bottom diameter: 11.6 cm, peripheral wall height: 5.6 cm, flange width: 1.4 cm). In the produced molded container, the moldability is "○" when the ratio of the container in which the bottom or wall surface of the container is perforated is 0.5% or less, and when the ratio is more than 0.5% and 1.0% or less. “Δ”, 1.0% or more was judged as “x”.

IH (Induction Heating) Suitability IH suitability was evaluated as an index of whether the aluminum alloy foil for an electromagnetic cooker has a sufficient electric resistivity. The IH suitability evaluation is performed by putting 300 cc of water into an aluminum alloy foil molding container after press molding and measuring the time required for the water temperature to rise from 20 ° C. to 90 ° C. by heating with an electromagnetic cooker. It was When the required time was 100 seconds or shorter, p was determined to be IH appropriate, “Δ”, when it was more than 100 seconds and 120 seconds or shorter, “Δ”, and when 120 seconds was exceeded, “x” was determined. If the evaluation is Δ or more, there is no problem in practical use, but it is desirable that the evaluation is ○. The test was performed at a height of 520 m above sea level, and an HT-B6S (200 V, 3.0 kW) manufactured by Hitachi, Ltd. was used as an electromagnetic cooker.

-Corrosion resistance Commercially available soy sauce (salt equivalent concentration: 160 g / L) was placed in a glass container, and an aluminum alloy foil was immersed in the glass container and kept at room temperature for 7 days and 20 days. Then, corrosion products were removed and visually determined. If no through holes were formed in 20 days, corrosion resistance was "○". If no through holes were formed in 7 days, if "through" was formed in 20 days, "△" was found. When it occurred, it was judged as "x". If the evaluation is Δ or more, there is no problem in practical use, but it is desirable that the evaluation is ○.
In terms of long-term corrosion resistance, the conventional chilled food cooker does not directly contact the container with the cooking liquid, but when using a frozen food cooker, etc. Therefore, high corrosion resistance is required.

1 Aluminum foil molding container
2 Orbiting side wall 3 Bottom

Claims (4)

  Si: 0.1 wt% or less, Fe: 0.21 to 0.40 wt%, Cu: 0.006 to 0.01 wt%, Mn: 0.5 to 3.0 wt%, Mg: 0.5 to 2.0 wt. %, Cr: 0.05 wt% or less, Zn: 0.05 to 0.50 wt%, and a balance of Al and unavoidable impurities, and an aluminum alloy foil for an electromagnetic cooking container.   The foil thickness is 65-150 micrometers, The aluminum alloy foil for electromagnetic cooking containers of Claim 1 characterized by the above-mentioned.   The aluminum alloy foil for an electromagnetic cooking container according to claim 1 or 2, wherein the average crystal grain size is in the range of more than 20 µm to 100 µm.   An aluminum foil forming container comprising the aluminum alloy foil for an electromagnetic cooking container according to claim 1.

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