JPH0341537B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an aluminum alloy plate with medium strength (tensile strength 20 to 26 Kgf/mm, class ² ) and excellent tearability.
More specifically, containers that are easy to tear off, such as caps, foil containers, or easy open cans.
This invention relates to an aluminum alloy plate for packaging that has low tear strength and is used as a material for lids, etc. (Prior Art and Problems to Be Solved) Conventionally, aluminum and aluminum alloys have been widely used as materials for caps, foil containers, easy-to-open cans, and the like. Aluminum and aluminum alloys used in these applications are required to have the property of being easily torn or torn apart. One example is a Ringpull cap.
The quality characteristics required for this cap material are (1) good drawability (shell forming), (2) strength to withstand internal pressure (when sealing is performed by applying gas pressure). (3) When used as a ring pull cap that is torn open from the score (cut groove), it has good tearing resistance and does not derail from the score, (4) Good sealing processability, (5 ) Good corrosion resistance, etc. are required. The applicant had previously published Japanese Patent Application Laid-Open No. 60-145346 and Japanese Patent Publication No. 145346,
As shown in No. 62-32264, we proposed an aluminum alloy plate with low strength (approximate tensile strength of 20 kg/mm ² or less) or high strength (approximate tensile strength of 28 kg/mm ² or more) and excellent tearability. However, recently, with the thinning of aluminum materials for this type of application, tensile strength of 20 to 26
There is a need for the development of an aluminum alloy plate with medium strength at the Kg/ ^mm2 level and excellent tearability. The present invention was made in response to such demands, and an object of the present invention is to provide an aluminum alloy plate having medium strength and excellent tearability. (Means for Solving the Problems) In order to achieve the above object, the present inventor conducted extensive research on the chemical composition and structure of aluminum alloy plates, and as a result, determined that specific amounts of Si and Fe are essential components, and We have discovered that this is possible by controlling the size and area ratio of the intermetallic compound after rolling. That is, in the present invention, Si≧0.10%, 0.5%≧Fe
Contains Si and Fe of ≧0.15% and 3Fe+Si≦3% as essential components, and if necessary, one or two of Cu: 1% or less, Mn: 1% or less, and Mg: 1% or less. An aluminum alloy containing the above, with the balance consisting of Al and impurities, characterized in that the size of the intermetallic compound after rolling is 30 μm or less, and the area ratio thereof is 4 to 10%. 20
~26Kgf/mm The gist is an aluminum alloy plate that is grade ² and has excellent tearability. The present invention will be explained in more detail below. First, the reasons for limiting the chemical components in the present invention will be explained. Si is an element that has the effect of improving drawability, improving strength, and reducing selvage. However, if it is less than 0.1%, there is no such effect, so the amount of Si needs to be 0.10% or more. Fe is a very important element in controlling the size and area ratio of intermetallic compounds. However, the content is 0.15
If the content is less than 0.15%, the formation of intermetallic compounds such as (Fe, Mn) Al ₆ will not be promoted, so 0.15% or more is required, but if it exceeds 0.5%, the strength will be insufficient, which is not preferable. However, the total amount of Si and Fe, that is, (3Fe +
If the Si content exceeds 3%, processability such as drawability will deteriorate. Therefore, Si and Fe
The amounts of Si≧0.10%, 0.5%≧Fe≧0.15%, and the amounts that satisfy 3Fe+Si≦3%. In addition, it is preferable that 3Fe+Si≦2% since good low ear properties can also be obtained. Although the above two elements Si and Fe are essential components, in the present invention, one or more of the following elements Mn, Mg, and Cu can be added as necessary. Mn is an element that has the effect of improving strength and forms an (Fe, Mn)Al ₆ intermetallic compound together with Fe, but if it is contained in an amount exceeding 1%, drawing workability etc. deteriorate. Therefore, the amount of Mn is set to 1% or less. Mg is an element that imparts strength, but if it is contained in the present alloy in an amount exceeding 1%, the strength increases and the formability decreases. Therefore, the Mg amount should be 1% or less. Cu is an element that imparts strength, but if it is contained in an amount exceeding 1%, moldability and corrosion resistance deteriorate.
Therefore, the amount of Cu should be 1% or less. In addition, impurities are contained in addition to the above ingredients,
0.05 each if containing Zn, Cr, Ti or Zr
% or less, it does not change the properties of the aluminum alloy plate of the present invention, which has medium strength and excellent tearability, so a content of up to 0.05% is permissible. Also B
(Boron) is also allowed for the same reason as long as its content is 0.03% or less. Furthermore, in the present invention, the chemical components are adjusted as described above, and the size and area ratio of the intermetallic compound after rolling are controlled. Specifically,
By setting the size of intermetallic compounds such as (Fe, Mn) Al ₆ after rolling to 30 μm or less and setting the area ratio to 4 to 10%, tearability and workability are improved. . However, if the size of the intermetallic compound exceeds 30 μm, it becomes a starting point for cracking during deep drawing, etc., and if the area ratio of the intermetallic compound is less than 4%, there is little deterioration in tearability; If it exceeds this, there will be no problem with tearability, but it will become a starting point for cracks during deep drawing, so it is not preferable. Note that in actual drawing, low directionality (low edge ratio) is required to reduce the amount of trimming, but this is due to the low directionality of soaking conditions, hot rolling conditions, intermediate annealing conditions, etc. It may be determined as appropriate. Of course, the aluminum alloy plate of the present invention is not limited to being used for ring caps, and can be similarly applied to other caps such as PP caps (Pilfer-Proof caps), foil containers, and easy-to-open cans. You can expect good results. In other words, in the case of PP caps, they are opened by tearing them along the perforations, but this is effective in reducing the opening torque at this time.
In addition, in the case of foil containers or easy-open can lids,
Multi-stage stretchability and riveting formability are required, but it can be formed without any problems. Next, examples of the present invention will be shown. (Example) An ingot of aluminum alloy having the chemical composition shown in Table 1 was made into a 55 mm thick ingot by semi-continuous casting method, faceted to 50 mm thick, and then heated at a temperature of 510°C for 4 hours to equalize the ingot. 3 by heat treatment and hot rolling at 500-300℃
It was made into a hot-rolled plate with a thickness of mm. Then, by cold rolling
The thickness was 0.50 mm, and after intermediate annealing at a temperature of 480°C, the thickness was made 0.25 mm by cold rolling again (cold working rate 50%). Thereafter, it was heated at a temperature of 190°C for 10 minutes (corresponding to normal paint baking conditions), and a can-end openability test (scoring rate 50%) was conducted. Can openability is determined by A, as shown in Figure 1, which shows the relationship between load and displacement.
Evaluation was made at each load (Kg) at point (score crack initiation: pump), point B (tear), and point C (rupture: detachment). Furthermore, after baking (190°C x 10 min), a tensile test was conducted to examine the mechanical properties, and the size and area ratio of the intermetallic compound were measured, as well as the ear ratio. These results are also listed in Table 1. The ear rate is
This is the value after 48% drawing. As is clear from Table 1, all of the examples of the present invention have a medium tensile strength of 20 to 26 Kg/mm ² and excellent openability (tearability). Also, the ear rate is small. On the other hand, although Comparative Examples No. 8 and No. 10 have excellent tearing properties, they lack strength, and Comparative Examples No. 9, No. 11 to No.
has excessive strength and poor tearability.

【table】

[Table] (Effects of the Invention) As explained above, according to the present invention, specific amounts of Si and Fe are adjusted as essential components, and the size and area ratio of intermetallic compounds after rolling are regulated. It has medium strength and excellent tearability, and is particularly suitable for lids of caps, foil containers, and easy-to-open cans.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between load and displacement in a can end openability test.

Claims (1)

[Claims] 1% by weight (the same applies hereinafter), Si≧0.10%, 0.5%
≧Fe≧0.15%, 3×Fe+Si≦3% of Si and Fe as essential components, the balance being Al and impurities, and the size of the intermetallic compound after rolling is 30 μm or less, Tensile strength 20-26 characterized by its area ratio being 4-10%
Kgf/mm ^2nd class aluminum alloy plate with excellent tear resistance. 2 The aluminum alloy may optionally be
Contains one or more of Cu: 1% or less, Mn: 1% or less, and Mg: 1% or less, with the remainder being
The aluminum alloy plate according to claim 1, which comprises Al and impurities.