JPH0273940A - Al alloy sheet for uncarbonated beverage can end - Google Patents

Abstract

PURPOSE:To improve bendability and rivet workability by subjecting an Al alloy having a composition in which Mg is contained as an essential component and further respective contents of Si, Fe, Cu, Mn, Cr, etc., are specified to heat and rolling treatments under respectively prescribed conditions. CONSTITUTION:An alloy which has a composition consisting of, by weight, 3-4% Mg as an essential component and the balance Al or further containing, besides the above, one or more kinds among <=0.3% Si, <=0.4% Fe, <=0.2% Cu, <=0.5% Mn, <=0.25% Cr, <=0.3% Zn, <=0.15% Zr, and <=0.2% Ti is refined. An ingot of the above alloy is subjected to homogenizing heat treatment and then to hot rolling. Subsequently, the resulting plate is cold-rolled at >=80% draft and process-annealed to undergo grain size regulation to <=15mum. The above sheet is further process-annealed and then cold-rolled at 30-70% draft.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an end material for non-carbonated cans such as fruit juice and coffee cans, and more particularly, to a non-carbonated can end material with excellent bendability and riveting property. The present invention relates to an aluminum alloy plate for use and a method for manufacturing the same.

(Prior Art and Problems to be Solved) A non-carbonated can is a container filled with contents that do not contain carbonic acid, such as fruit juice or coffee drinks, and whose interior is subjected to negative pressure.

Conventionally, AA5052 has been used as an end material for non-carbonated cans.
After hot rolling an Al alloy ingot having the following components, a material is used that is cold rolled at a relatively high rolling rate.

On the other hand, in recent years, as non-carbonated can ends have become thinner, there has been a demand for materials that have relatively high strength and are excellent in bending workability and riveting workability, which are important properties of end materials.

In other words, non-carbonated cans have negative pressure inside the can,
During sterilization of the contents (so-called retort processing), the inside of the can is heated and pressurized at 2 to 3 kg/cm'', and appropriate strength is required to prevent the end from deforming.

Moreover, when the can is opened, the en 1- is subjected to bending deformation, and if the bendability of the material is poor, cracks may occur and the spout surface may not open. Furthermore, as non-carbonated can end materials become thinner and stronger, their riveting properties deteriorate, so there is a demand for non-carbonated can end materials that have higher strength and better bendability and riveting properties than conventional materials. be.

However, the strength was improved with the conventional A A 5052.
In order to achieve this, it is necessary to perform further cold rolling.
When subjected to high cold rolling, the crystal grains become flat and elongated grains, which causes a problem of deterioration of bendability and riveting workability.

In addition, AA50, which is used for beer and carbonated drink cans, etc.
When non-carbonated can end materials such as No. 82 and AA5182 are used, although they are effective in increasing the strength, there is a problem that the strength is too high, leading to a decrease in bendability and riveting workability. Furthermore, when these alloy materials are used, final annealing is essential, but since final annealing is performed at a relatively high temperature (approximately 280°C), degreasing is usually required to prevent rolling oil from seizing. Moreover, since the range of annealing temperatures is narrow and the accuracy of annealing temperature is important, highly accurate annealing equipment is required, leading to higher manufacturing costs compared to conventional materials. There is.

For example, the manufacturing method disclosed in U.S. Pat. However, in order to apply it to end materials for non-carbonated cans, annealing at a higher temperature is required.

In addition, Japanese Patent Publication No. 62-9177 shows a can body, end, and tab as Af1 alloy plates for cans, but these have too much strength compared to the conventional AA5052, so they have poor bendability and riveting properties. Furthermore, by subjecting such aluminum alloy materials for cans to finish annealing, bendability and riveting workability can be improved, but the manufacturing cost is high and the finish annealing temperature range is high. is narrow and difficult in practice.

The present invention has been made to solve the problems of the prior art described above and to meet the above-mentioned needs, and includes an aluminum and alloy plate for non-carbonated can ends having particularly excellent bendability and riveting workability, and a method for manufacturing the same. The purpose is to provide the following.

(Means for Solving the Problems) In order to achieve the above object, the present inventors focused on the decrease in bendability and riveting workability when high strength is achieved using existing materials, and developed a material that can be produced at a relatively low cost. We conducted extensive research with the aim of developing an Al alloy material for non-carbonated can ends that has high strength and excellent bendability and riveting workability.

First, the present inventors investigated bendability and riveting property, and found that the smaller the crystal grains, the better these properties were, and that this was greatly affected by the rolling rate before intermediate annealing. Furthermore, by appropriately controlling the rolling rate after intermediate annealing, a non-carbonated can end material with relatively high strength, excellent bendability and riveting workability, and small anisotropy can be obtained without final annealing. I found it. Therefore,
We have discovered that the initial objective can be achieved by adjusting the chemical components based on our extensive knowledge and particularly regulating the conditions of the cold rolling process, and have hereby created the present invention.

That is, the present invention contains Mg: 3.0 to 4.0% as an essential component, and further contains Si≦0.30% and F as necessary.
e50.40%, Cu≦0.20%, Mn≦0.50%
, Cr≦0.25%, Zn≦0.30%, Zr≦0.1
5% and one or more of Ti≦0.20%, and the remainder is Afl and unavoidable impurities, and has excellent bendability and riveting property. The main subject is alloy plates.

In addition, the manufacturing method is to homogenize an Al gold alloy ingot having the above chemical composition, then hot-roll it, then cold-roll it at 80% or more, and then perform intermediate annealing to form a rolled plate. Non-carbonated can engine 1- with excellent bendability and rivet workability characterized by having a crystal grain size of 15 μm or less as seen from the surface and cold rolling at a rolling rate of 30 to 70% after the intermediate annealing. The gist of this paper is a method for manufacturing an Al alloy plate.

The present invention will be explained in more detail below.

(Function) First, the reasons for limiting the chemical components of the Al-gold alloy used in the present invention will be explained.

Mg: Mg is an important element that imparts strength, and is an essential component in the present invention. Unless it is added at least 3.0% as an end material for non-carbonated cans, the strength will be low and it cannot be used. However, if too much is added, the strength will be too high and formability will deteriorate, so the upper limit of the amount added is 4.
．． It is 0%.

Therefore, the amount of Mg added is in the range of 3.0 to 4.0%.

In the present invention, in addition to the above-mentioned Mg as an essential component, one or more of the following elements may be included as necessary.

Fe: The addition of Fe has a great effect on grain refinement, and the larger the amount added, the more refined the grains are. However, if it is added in excess of 4.0%, although it is effective for grain refinement, the number of crystallized substances produced increases, leading to a decrease in bendability. Therefore, the amount of Fe added is 0.40% or less.

Sj: Like Fe, addition of Si is effective in refining crystal grains, but when added in excess of 0.30%, crystallized products, especially Mg2Si crystallized products, are generated in large quantities. , leading to a decrease in bendability.゛Therefore, the amount of Si added is 0.3
0% or less.

Cu: Addition of Cu is effective in improving strength. However, 0.20
If it is added in excess of more than %, the strength will be too high, resulting in a decrease in moldability and corrosion resistance. Therefore, the amount of Cu added is 0.20% or less.

Mn, Cr: Addition of Mn and Cr has a great effect on improving strength and refining grains. However, if it is added in excess, the number of large particles and crystallized substances will increase, resulting in a decrease in bendability. The respective upper limits are 0.50% for Mn and 0.50% for Cr.
It is 25%. Therefore, Mn is 0.50% or less, C
r is 0.25% or less.

Zn: Addition of Zn improves formability such as bendability and stretchability, and improves the (M n , Fe) A Q seen from the rolled plate surface.
It has the effect of reducing the size of crystallized intermetallic compounds in No. 6.
However, if added in excess of more than 0.30%, corrosion resistance will deteriorate. Therefore, the amount of Zn added is 0.30%
The following shall apply.

Zr and TiAlthough Zr and Ti are effective elements for stabilizing the structure, if they are added in large amounts, they form giant compounds and reduce bendability. Each condition is Zr is 0.15
%, and Ti is 0.20%. Therefore, Zr is 0.
15% or less, and Ti is 0.20% or less.

Next, the manufacturing process of the present invention will be explained.

The Al-gold alloy having the above chemical components is melted and cast by a conventional method, and the ingot is subjected to homogenization heat treatment, followed by hot rolling.

After hot rolling, cold rolling is performed, and the method of the present invention is most characterized in that the cold rolling process including intermediate annealing is performed under specific conditions, as shown below.

The cold rolling rate before intermediate annealing is a condition that has a large effect on the grain size after intermediate annealing. If the rolling rate is less than 80%, the grain size after intermediate annealing will be large, resulting in poor bendability and rivet properties at the later product thickness. Processability decreases.

Therefore, the rolling ratio before intermediate annealing is set to 80% or more.

Intermediate annealing is then performed, and the smaller the grain size after intermediate annealing, the better the bendability and riveting workability, and the grain size as seen from the surface of the rolled plate is preferably 15 μII+ or less. Therefore, the intermediate annealing is performed under conditions that will yield crystal grains of a reasonable size.

The rolling ratio in cold rolling after intermediate annealing is a condition that affects strength, bendability, riveting property, and anisotropy, and a rolling ratio of less than 30% is preferable for bending property, riveting property, and anisotropy. However, the required strength cannot be obtained.

Further, although increasing the rolling rate is effective for improving strength, if the rolling rate exceeds 70%, the strength is too high, leading to a decrease in bendability and riveting workability, and an increase in anisotropy. Therefore, the cold rolling rate after intermediate annealing is 30 to 70.
% range.

(Example) Next, examples of the present invention will be shown.

Example: An ingot of Hemium alloy having the chemical composition shown in Table 1 was subjected to homogenization heat treatment at 500°C for 3 hours, and then hot rolled to a plate thickness of 4 mm. did.

Then, by cold rolling, 14q1 was reduced to 1.25 mm, H
a 2-1 is 0.55 mm, Nn3 is 0.55 mm, N
A41 was set to 0.33 mm, and Na4-2 was set to 1.25 mm. Further, Nα2-2 was once softened to a plate thickness of 1.1 mm so that the rolling reduction before intermediate annealing was 50%, and then further cold rolled to a thickness of 0.55 mm.

Thereafter, CAL annealing (heating/cooling rate 700° C./min, final temperature 450° C., holding time 2 seconds) was performed, and the product was further cold rolled to a thickness of 0.25 mm. Here, the difference in plate thickness during intermediate annealing was adjusted to keep the strength constant, and the respective rolling rates before intermediate annealing and rolling rates before intermediate annealing are shown in Table 2. In addition, after No. 4-2 was cold-rolled to the product thickness, finish annealing was performed at 270''C for 2 hours.

In addition, since the end material is molded after painting, the
'CX Baking treatment was performed for 20 minutes under the same conditions as when painting.

Table 3 shows the material properties (mechanical properties, bendability, rivet protrusion height, and crystal grain size) of the product plate with a thickness of 0.25 mm after baking treatment.

In addition, the bendability is 0° (direction perpendicular to the force direction RD) and 18
A 180° close bending test (see Figure 1) was conducted in the 0° direction (RD force direction), and judgment was made according to the degree of crack occurrence in the bent part. ◎ (Excellent) → O → △ → × (Poor) In addition, the rivet protrusion height was evaluated based on the 3rd] second limit protrusion height h3 (+++II
+) was calculated and evaluated. The grain size was determined after medium 1711 annealing.

From Table 3, the following considerations can be made.

Nn 2-1 and Na 3 in the examples of the present invention have small crystal grain sizes and are excellent in bending properties and rivet extension properties. In addition, appropriate high strength was obtained.

However, comparative example &4. -1 has a small grain size and is excellent in bendability and rivet extension property as in the above-mentioned invention example, but the plate thickness during intermediate annealing is thin, and when the CA L # is dull, there is a problem in plate threadability. Furthermore, when intermediate annealing is performed in a batch manner, problems arise in surface properties, which is a practical problem.

Comparative Example Nu ] is a conventional material (AA5052), which is inferior in both bending properties and rivet extension properties, and Comparative Example Na 2
-2 has a large crystal grain size and is poor in bending properties and rivet extension properties. Moreover, comparative example N04-2 is AA508
This is an example of No. 2 in which finish annealing was performed, and the bendability and rivet extension property are poor, and the anisotropy is large.

[Left below is blank space] 11 Rough λ In Example 1, a hot rolled sheet of Al alloy having the chemical components shown in 1Ja2 and Na3 in Table 1 (within the scope of the present invention) was cold rolled to a thickness of 1.00 mm. (A), 0.56
After setting mm+(B) and 0.33mm(C), CA
, L annealing (conditions: the same as in Example 1) was performed, and then cold rolling was performed to give a product thickness of 0.25 mm+. A, B above
The cold rolling ratios before intermediate annealing of and C are 75% and 86
%, 92%, and the cold rolling rate after intermediate annealing is 75%, 55
%, 24%.

In addition, since the end material is molded after painting, Example 1
Similarly, perform baking treatment at 200°C for 20 minutes,
The conditions were the same as when painting.

Table 4 shows the material properties (mechanical properties 1: bendability, rivet protrusion height, and crystal grain size) of the product plate with a thickness of 0.25 mm after baking treatment. Note that the evaluation method for each characteristic is the same as in Example 1.

In Table 4, Nα2-B and Na 3-B are the results of Nn 2-1 and Nα3 of Example 1, respectively, and both have excellent bendability and rivet extension property, and appropriate strength.

However, Comparative Examples Na2-A and N113-A had too high strength, leading to a decrease in workability, and Na2-C
and Nα3-C have low strength and may not be able to withstand the internal pressure during retort processing, which poses two practical problems.

(The following is a blank space) (Effects of the Invention) As detailed above, according to the present invention, it is possible to improve the bendability and rivet workability of end materials for non-carbonated cans such as fruit juice and coffee cans. It minimizes cracking during bending deformation, which is a problem with existing materials, improves rivet extension properties, and also provides appropriate strength, so the use of the present invention material can adequately handle high-strength and thin-walled materials. It is something. It is also superior in terms of manufacturing (stability, cost).

[Brief explanation of the drawing]

Figures 1 (a) and (b) are diagrams explaining the procedure of the 180° close bending test, respectively. (a) shows the case when the bending is perpendicular to the RD force direction, and (b) shows the case when the bending is performed in the RD force direction. , FIGS. 2(a) to 2(c) are explanatory diagrams showing the overhang height after the rivet overhang process consisting of the first to third steps, respectively. Patent applicant Hisashi Nakamura, patent attorney representing Kobe Steel, Ltd.

Claims (3)

[Claims] (1) In weight% (the same applies below), Mg: 3.0 to 4.0%
An Al alloy plate for non-carbonated can ends having excellent bendability and riveting property, characterized in that it contains as an essential component and the remainder consists of Al and unavoidable impurities. (2) Mg: Contains 3.0 to 4.0% as an essential component,
Furthermore, Si≦0.30%, Fe≦0.40%, Cu≦0.
20%, Mn≦0.50%, Cr≦0.25%, Zn≦
0.30%, Zr≦0.15%, and Ti≦0.20%, and the remainder is Al and unavoidable impurities. Al alloy plate for non-carbonated can ends with excellent properties. (3) After homogenizing an ingot of an Al alloy having the chemical composition according to claim 1 or 2, hot rolling is performed, and after further cold rolling at 80% or more, intermediate annealing is performed,
The grain size as seen from the surface of the rolled plate is set to 15 μm or less,
A method for producing a non-carbonated aluminum alloy plate for can ends having excellent bendability and riveting property, which further comprises cold rolling at a rolling rate of 30 to 70% after the intermediate annealing.