JPH07100843B2 - Manufacturing method of aluminum alloy plate for medium strength cap with excellent ductility - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing an aluminum alloy plate for a medium-strength cap having excellent ductility, and more particularly, to high deformability and impact resistance. The present invention relates to a method for producing an aluminum alloy plate for a medium-strength cap which is excellent in sealing property and opening property.

(Prior Art and Problems to Be Solved) Conventionally, aluminum and aluminum alloys have been often used as materials for caps and the like. Aluminum and aluminum alloy plates used for these applications include
The property of being easily torn or torn off is required first. This is the gender of the person who opens the cap,
Because the width of the age group is unspecified, anyone must be able to easily open the cap.

The applicant of the present invention has previously disclosed that, as shown in JP-A-60-145346,
Relatively low strength (tensile strength of about 20 kg / mm ² or less),
We proposed an aluminum alloy plate with excellent tearability.

However, in recent years, with the spread and diversification of bottled beverages, in addition to the excellent tearability described above, while maintaining the strength to withstand the internal pressure fluctuation due to the gas pressure of carbonated beverages or the temperature change during filling, it can be dropped or dropped. Even if the entire cap is deformed and the cap comes off at the time of impact, the contents do not flow out,
That is, an aluminum alloy plate for a cap having ductility (deformability) capable of partially absorbing impact force has been required.
In this respect, the conventional aluminum alloy plate for a cap has an elongation of 4 to 6% in terms of mechanical properties, and does not have sufficient ductility.

The applicant has also previously proposed a medium-strength aluminum alloy sheet (tensile strength of about 20 to 26 kg / mm ² ) excellent in tearability as shown in Japanese Patent Application No. 63-110063.

However, in comparison with the material strength, even if the tearability was excellent, the strength itself was high, and therefore the tearing force was large in absolute amount.

As mentioned above, the aluminum alloy for a cap should have a low tearing force. Therefore, the tensile strength is about 15 to 17
An aluminum alloy with a standard of kg / mm ² was required.
Moreover, it must have sufficient ductility, like the above-mentioned conventional aluminum alloy plate for caps.

As an example of the use of aluminum alloy plates for caps, the ring pull cap will be explained. The general quality characteristics required for this cap material are good drawability (shell molding) and sealing by applying gas pressure. When it is used or when the internal pressure changes, it must have the strength (sealing property) to withstand the internal pressure, and when used as a ring pull cap that can be cut open from the score (cut groove), tearability is good,
In addition, do not derail from the score, have less ears, do not reduce the product value in appearance such as flow marks, rough skin, etc.If handled by a vending machine or dropped, it may be deformed by shock. It is required that the cap does not spread over the entire cap and can be suppressed by only a part of the dent.

Generally, the higher the strength of the material, the higher the tearing force.Therefore, as an aluminum alloy for caps, it has a strength that balances the sealing property and the tearing property (tensile strength is approximately 15 to 17 kg / mm ² ), and has a high strength. A ductile (elongation rate of 9% or more) material is required.

An object of the present invention is to provide a method for producing an aluminum alloy plate for a cap, which satisfies such requirements and has an intermediate strength and excellent ductility.

(Means for Solving the Problem) In order to achieve the above-mentioned object, the present inventor diligently studied a method for producing an aluminum alloy plate, and found that a specific amount of Si,
Fe and Mn as essential components, the intermediate annealing temperature, by the manufacturing method of controlling the rolling rate and the stabilizing annealing temperature of the cold rolling after the intermediate annealing, it was found that it is possible, and the present invention has been made here. is there.

That is, the present invention, 0.1% ≤ Si ≤ 0.6%, 0.1% ≤ Fe ≤
Contains 0.7% and 0.8% ≤ Mn ≤ 1.0% as essential components,
After homogenizing the aluminum alloy ingot with the balance consisting of Al and impurities, hot rolling, and then cold rolling, at a temperature of 400 ~ 500 ℃, the size of the intermetallic compound
After the intermediate annealing of 30μm or less, the rolling rate is 30-60%
The gist is a method for producing an aluminum alloy plate for a medium-strength cap having excellent ductility, which is characterized by cold rolling in, followed by stabilizing annealing at 200 to 250 ° C.

The present invention will be described in more detail below.

(Operation) First, the reasons for limiting the chemical components in the present invention will be described.

Si: Si is an element that has the effect of improving the drawability, strength, and lowering the ear rate, but if it is less than 0.1%, such an effect cannot be obtained, so the Si content must be 0.1% or more. . But,
If it exceeds 0.6%, the workability such as drawability deteriorates (for example, wrinkles occur), so the upper limit of the Si content is made 0.6%.

Fe: Fe is an element that is very important for the size and abundance of intermetallic compounds, but if the content is less than 0.1%, the formation of intermetallic compounds such as (Fe, Mn) Al ₆ is not promoted and tearability is high. Is worse, so 0.1% or more is required. However, if it exceeds 0.7%, the workability such as drawability is lost, so the upper limit of the Fe content is made 0.7%.

Mn: Mn forms an intermetallic compound such as (Fe, Mn) Al together with Fe,
It has the effect of improving tearability. Further, Mn is an element having an effect of improving strength. However, if it is less than 0.8%, it is less effective as a cap material requiring sealing property, that is, strength, so 0.8 or more is required. However, 1.0%
If it is contained in excess of 1, the strength becomes too high and the moldability is lowered, which is not desirable. Therefore, the upper limit of the amount of Mn is 1.0
%.

Although it may contain impurities in addition to the above components, Cu, Mg,
When Cr, Zn, and Ti are contained, if the content is 0.05% or less, the characteristics of the aluminum alloy plate for a medium-strength cap excellent in ductility obtained by the method of the present invention are not changed, so 0.05% or less respectively. Permissible.

Next, the manufacturing method will be described.

The aluminum alloy ingot having the above chemical composition is homogenized by a conventional method, hot rolled, and then annealed. In the intermediate annealing, when the temperature is lower than 400 ° C., a batch type annealing furnace is generally used, so that the crystal grain becomes coarse due to the influence of the temperature rising rate, and the roughening occurs during the cap processing. On the other hand, 50
If it exceeds 0 ° C, Mn will be solid-solubilized and the strength will increase too much. Further, there is a risk of coarsening of crystal grains and burning at higher temperatures. Therefore, the temperature of the intermediate annealing is 400
Within the range of ~ 500 ℃. However, the size of the intermetallic compound is 3
If it exceeds 0 μm, the surface of the cap will be roughened during the cap processing, so the size of the intermetallic compound should be 30 μm or less. For this, it is sufficient to use a continuous heating furnace (CAL) capable of setting the heating / cooling time to 100 ° C / min or more. In the case of CAL, retention time of 10 seconds or less is sufficient.

After the intermediate annealing, cold rolling is performed, but if the cold rolling rate is less than 30%, the strength required for sealing performance cannot be obtained. On the other hand, if it exceeds 60%, the strength immediately after rolling becomes high, and the stabilizing annealing temperature must be increased in order to obtain the finally required strength and ductility, and the temperature crossover becomes small. In this case, due to a slight difference in temperature conditions, the material is just before softening,
It is not preferable because it is in a softened state or the strength is unstable. On the other hand, if it exceeds 60%, the anisotropy increases and the ear rate increases, which is not preferable. Therefore, the cold rolling rate after the intermediate annealing is in the range of 30 to 60%.

Stabilization annealing is performed after this cold rolling, and the conditions for stabilizing annealing are determined by the relationship between the cold rolling rate after intermediate annealing and the required strength. However, if the stabilizing annealing temperature is less than 200 ℃, baking (190 to 200
(° C) causes a decrease in strength, and stable strength cannot be obtained unless the baking conditions (temperature and time) are constant. In addition, the ductility is low, and cracks and wrinkles will occur during cap processing. On the other hand, if the temperature exceeds 250 ° C, it will start to soften and the strength will suddenly decrease. In addition, the crystal grains become coarse, which causes rough skin and lowers the product price as a cap. Therefore, stabilization annealing is 200-250
Must be done at a temperature of ° C.

In actual drawing, as low a directionality (low ear ratio) as possible is required in order to reduce the trimming amount. This is because homogenization treatment conditions, hot rolling conditions, intermediate annealing conditions, etc. It may be appropriately determined so as to have low directivity.

Further, the aluminum alloy sheet obtained by the method of the present invention is expected not only to be used for medium-strength caps such as ring pull caps, but also to be applied to lids such as foil containers or simple open cans (easy open cans), and similar effects are expected. it can. That is,
In the case of a foil container or a lid of a simple open can, multi-stage overhanging workability and rivet formability are required, but this can also be formed without problems.

(Example) Next, the Example of this invention is shown.

Example 1 An aluminum alloy having the chemical composition shown in Table 1 was ingoted by a semi-continuous casting method to a thickness of 55 mm, chamfered to a thickness of 50 mm, and then homogenized by heating at a temperature of 510 ° C. for 4 hours. It was hot-rolled at 500-300 ℃ to make 3mm thick hot-rolled sheet.
Next, after cold rolling to a thickness of 0.50 mm, intermediate annealing was performed at a temperature of 480 ° C., and then cold rolling again to a thickness of 0.25 mm (cold working rate 50%). Then, stabilization annealing was performed at 230 degreeC.

About the obtained aluminum alloy plate, the mechanical properties are examined by a tensile test and a tear test, and it is processed into a cap, which is attached to a container and the internal pressure is applied to measure the pressure when the cap comes off, and the height is 50 cm. The deformation degree of the cap by the drop test was investigated. The results are also shown in Table 1.

As is clear from Table 1, the aluminum alloy sheets obtained in the examples of the present invention have desired mechanical properties (tensile strength, elongation, tear strength) as a medium-strength cap, and are ductile and deformable. It has high performance, little deformation when dropped, etc., excellent impact resistance, and good sealing and opening properties.

On the other hand, the comparative example having a chemical component outside the scope of the present invention does not satisfy any of the characteristics as a medium-strength cap.

Example 2 For the No. 1 aluminum alloy (chemical composition within the scope of the present invention) shown in Table 1, the hot-rolled sheet obtained in Example 1 was subjected to cold rolling conditions and intermediate annealing shown in Table 2. 0.25mm under the condition
The thickness was made thicker, and stabilization annealing was performed at the temperature shown in Table 2.
Mechanical properties of the obtained aluminum alloy plate were examined by a tensile test and a tear test in the same manner as in Example 1. The results are shown in Table 2.

From Table 2, the present invention example No. 1 is the present invention example N in the first embodiment.
It is the same as that of o.1 and excellent results are obtained, whereas good results are not obtained in Comparative Examples No. 2 to No. 6.

That is, No. 2 has insufficient strength because the cold rolling rate after the intermediate annealing is too small. In No. 3, the cold rolling rate after the intermediate annealing was too large, so the tearability was poor and the ear rate was high. No. 4 is an example in which a batch type furnace is used to lower the intermediate annealing temperature, and therefore the intermetallic compound becomes large and rough skin occurs. In No. 5, the stabilization annealing temperature is too low, so that the ductility is inferior. In No. 6, on the contrary, the stabilization annealing temperature is too high, resulting in rough skin and low strength.

(Effects of the Invention) As described in detail above, according to the present invention, a specific amount of Si, Fe
And Mn as essential components are adjusted, and the intermediate annealing conditions, cold rolling rate after intermediate annealing, and stabilizing annealing temperature are controlled, so high deformability, excellent impact resistance, and sealing and opening. An aluminum alloy plate for a medium-strength cap having good properties can be obtained.

Claims (1)

[Claims] 1. In weight% (hereinafter the same), 0.1% ≦ Si ≦ 0.6
%, 0.1% ≤ Fe ≤ 0.7% and 0.8% ≤ Mn ≤ 1.0% are contained as essential components, and the balance is aluminum alloy ingot consisting of Al and impurities, after homogenization treatment, hot rolling, then,
After performing cold rolling and further performing intermediate annealing at a temperature of 400 to 500 ° C. so that the size of the intermetallic compound becomes 30 μm or less,
A method for producing an aluminum alloy sheet for a medium-strength cap having excellent ductility, which comprises cold rolling at a rolling rate of 30 to 60% and then stabilizing annealing at 200 to 250 ° C.