JPH05339670A - Aluminum alloy hard sheet having high strength and excellent in cup distortion pattern and its manufacture - Google Patents

Abstract

PURPOSE:To efficiently suppress a distortion pattern at the time of cup forming and particularly to provide an aluminum alloy hard sheet having high strength and its manufacturing method. CONSTITUTION:The objective aluminum alloy hard sheet having high strength of >=30kgf/mm<2> tensile strength and excellent in a cup distortion pattern is a one characterized, in an aluminum ally contg. 0.5 to 1.5% Mn, 0.5 to 1.5% Mg and 0.05 to 0.5% Cu, and the balance Al with inevitable impurities, by distributing precipitates of >=0.2mum per <=0.5 piece/mum<2> and precipitates of <=0.1mum per >=1 piece/mum<2>. This alloy hard sheet is obtd. by subjecting the ingot of an aluminum alloy having this chemical components to homogenizing heat treatment, finishing hot rolling so as to regulate the final sheet thickness to 1.5 to 3.0mm, executing cold rolling at need, or without executing it, subjecting it to solution heat treatment at 550 to 620 deg.C, then executing precipitating treatment in the temp. range of 150 to 250 deg.C, and furthermore, subjecting it to cold rolling of >=30%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy hard plate, and more particularly, as a beverage can body, a high-strength aluminum alloy having an excellent distortion pattern on the side wall of the squeezing cup during the squeezing process before the DI process. The present invention relates to a hard plate and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, Al-Mn-Mg-based 3004 alloy hard plates have been used as a material for beverage can bodies for beer and carbonated drinks. These cans are generally formed by first making a deep drawn cup and then DI processing.

However, in the conventional method, when a deep-drawing cup is molded, a distortion pattern (SS mark, Luders mark, Kagome pattern, etc.) is generated on the side wall of the cup, and a pinhole or a crack is generated at the portion where the distortion pattern is generated. Could occur. Further, even when no pinholes or cracks are formed during cup molding, the friction force is increased by the next DI processing, which causes tear-off.

Conventionally, a method of heat treatment has been generally used in order to suppress the distortion pattern at the time of cup molding, but in this method, the work hardening of the material during the processing of the can body becomes large, and therefore, the tear is applied. There was a problem that off (breaking of the can body) was likely to occur. Further, for example, Japanese Patent Laid-Open No. 1-272
In No. 749, the solution heat treatment and the precipitation treatment are combined to improve the formability, but the formability (LDR, Erichsen value) used conventionally and the distortion pattern generated during cup forming have little relation to each other. This method was insufficient to reduce the distortion pattern.

An object of the present invention is to solve the above-mentioned problems of the prior art, to effectively suppress the distortion pattern at the time of cup molding, and to provide a particularly strong aluminum alloy hard plate and a manufacturing method thereof. There is.

[0006]

The inventor of the present invention has completed the present invention as a result of intensive studies for solving the above-mentioned problems.

That is, according to the present invention, Mn: 0.5 to 1.5
%, Mg: 0.5-1.5% and Cu: 0.05-0.5%, the balance being Al and unavoidable impurities in an aluminum alloy containing 0.2 .mu.m or more of precipitates. 5 deposits / μm ² or less and 1 deposit / 0.1 μm or less
Tensile strength of 30 kg characterized by distribution of more than μm ²
The gist is an aluminum alloy hard plate having a high strength of f / mm ² or more and an excellent cup distortion pattern.

Further, in the manufacturing method, the aluminum alloy ingot having the above chemical composition is subjected to homogenizing heat treatment, and then hot rolling is finished at a plate thickness of 1.5 to 3.0 mm, and if necessary, cooled. 550-62 with or without hot rolling
Solution heat treated at a temperature of 0 ° C., then 150-25
It is characterized in that the precipitation treatment is carried out in the temperature range of 0 ° C., and further cold rolling of 30% or more is carried out.

[0009]

[Action]

The present invention will be described in more detail below. First, the reasons for limiting the chemical components in the present invention are as follows.

Mn: Mn is an element effective in improving strength. However, if it is less than 0.5%, the effect is small, and if it exceeds 1.5%, the strength becomes too high and the moldability is deteriorated. Therefore, the amount of Mn should be in the range of 0.5 to 1.5%.

Mg: Mg is an element effective in improving the strength, and when combined with Cu, it forms an Al-Cu-Mg type fine precipitate and is effective in reducing the strain pattern. However, if it is less than 0.5%, its effect is small, and if it exceeds 1.5%, the strength becomes too high, resulting in deterioration of moldability. For the above reason, the amount of Mg is set in the range of 0.5 to 1.5%.

Cu: Cu is an element having the same effect as Mg, and is effective in improving the strength and forming Al—Cu—Mg type fine precipitates and reducing the strain pattern. But 0.05
If it is less than 0.1%, the effect is small, and if it exceeds 0.5%, the strength becomes too high, resulting in deterioration of moldability. For the above reasons, the amount of Cu is set to be in the range of 0.05 to 0.5%.

The balance is Al and impurities, but it is preferable that the impurities are as small as possible. However, in consideration of recycling of the aluminum alloy material, Fe, Si, and Zn, which may be mixed as impurities, have Fe: 0.0
7% or less, Si: 0.5% or less and Zn: 0.5% or less can be mixed, and the effect of the present invention is not adversely affected.

Next, the precipitate, which is the greatest feature of the present invention, will be described.

By distributing the precipitates of 0.1 μm or less at 1 piece / μm ² or more, the movement of dislocations is finely stopped by the fine precipitates when the flange is deformed during deep drawing, so that it is concentrated at a certain point. As a result, the distortion in the circumferential direction of the cup is made uniform and the distortion pattern on the side wall of the cup is suppressed. If the precipitates or distributions exceeding 0.1 μm or less than 1 / μm ² do not have a uniform pinning effect of dislocations, the strain in the circumferential direction becomes uniform, and there is no effect in suppressing the strain pattern on the sidewall of the cup.

On the other hand, precipitates having a size of 0.2 μm or more have a small effect of fixing dislocations, and have a small effect on making the strain uniform. Furthermore, if the number of precipitates of this size is greater than 0.5 / μm ² , the above effect is eliminated in order to suppress the distribution of precipitates of 0.1 μm or less.

For the above reasons, the precipitate content is less than 0.1.
The precipitates of 2 μm or more are suppressed to 0.5 / μm ² or less, and the precipitates of 0.1 μm or less are distributed to 1 / μm ² or more.

Next, the manufacturing method of the present invention will be described in detail.

The aluminum alloy having the above chemical composition is melted and cast by a conventional method (DC casting or the like), and the obtained ingot is subjected to homogenizing heat treatment and subsequently hot rolled. Regarding the homogenizing heat treatment and hot rolling conditions, in the case of materials normally used for beverage cans, the homogenizing heat treatment is performed at a temperature of 500 to 620 ° C. for 1 hour or more, and the hot rolling is performed at a start temperature of 450. ℃ or more, finish plate thickness 1.5-3.0
mm, the end temperature is preferably 300 to 350 ° C.
If the starting temperature is less than 450 ° C., it is difficult to set the ending temperature to 300 ° C. or higher due to the temperature decrease during hot rolling, the structure becomes fibrous, and the formability (DI processability) in the product is lowered. Even if the start temperature is 450 ° C. or higher, if the hot end temperature is lower than 300 ° C., the structure becomes fibrous as described above, which is not preferable. Especially the finished plate thickness is 3.0mm
If it exceeds, the crystal grains at the end of hot rolling become coarse and the formability at the time of production is lowered, which is not preferable.
On the other hand, if it is less than 1.5 mm, the desired strength cannot be obtained and the ears become large, which adversely affects the moldability. In either case, high strength with a tensile strength of 30 kgf / mm ² or more cannot be obtained with excellent moldability.

Next, solution heat treatment is performed, and this heat treatment is performed after hot rolling or after cold rolling that is performed subsequent to hot rolling. This heat treatment is for re-dissolving the precipitates generated by the homogenizing heat treatment and the hot rolling. However, if the temperature is less than 550 ° C, re-dissolution is not sufficient, while
If it exceeds 20 ° C, burning tends to occur. For the above reasons, the solution heat treatment is performed in the range of 550 to 620 ° C. When cold rolling is performed after hot rolling, the finish cold rolling rate is smaller than when cold rolling is not performed after hot rolling. Excellent in overhanging property required. If cold rolling is not performed after hot rolling, the work hardening of the product will be small, and there will be no problem in melting the neck and flange workability required for can body materials, and a process requiring more important workability. Should be selected.

Next, a precipitation treatment is carried out. This treatment is different from the above-mentioned Japanese Patent Laid-Open No. 1-272749. In the present invention, a large amount of fine precipitates can be distributed by performing the precipitation treatment temperature in the range of 150 to 250 ° C. As a result, when the flange during deep drawing deforms, the strain becomes uniform in the circumferential direction of the cup, and the strain pattern on the side wall of the cup is suppressed. However, if the temperature is lower than 150 ° C., it takes a very long time for precipitation, which is not practical. Also, 250
If the temperature exceeds ° C, the fine precipitates re-dissolve or grow, so that they do not hinder the movement of dislocations and concentrate at a certain portion. In other words, the strain becomes uneven in the circumferential direction of the cup,
A distortion pattern occurs on the side wall of the cup.

Finally, finish cold rolling is performed to obtain a product sheet thickness. At this time, if the finish rolling rate is less than 30%, the strength required for the body of the beverage can cannot be obtained, so the finish cold rolling rate is set to 30% or more.

Next, examples of the present invention will be described.

[0025]

Example 1

[Table 1] Aluminum alloys with chemical components shown in Table 1 have a temperature of 580 ° C x 4
After Hr homogenization heat treatment, hot rolling (starting temperature 58
0 ° C., finish temperature 330 ° C., finish plate thickness 2.0 mm) and then cold rolling to a thickness of 0.7 mm. After that, 600 ℃
After the solution heat treatment of × 24Hr, 200 ° C × 24
An Hr precipitation treatment was performed. After that, it is cold rolled to 0.3.
The product plate thickness was mm (cold rolling rate 57%). The results of examining the characteristics of the products are shown in Tables 2 and 3. The evaluation of the formability of the product plate is as follows.

[Table 2]

[Table 3]

The limit drawing ratio (LDR) is the drawing ratio that can be formed by changing the blank diameter using an Erichsen tester.
It was determined by (blank diameter / punch diameter). Punch diameter is 33mm
φ, using Dydro-N as the lubricating oil, and having a wrinkle holding force of 500 kgf. Also, the overhanging property (Erichsen value) is J
It was evaluated by the Erichsen test B method of IS.

A blank diameter of 150 mm is evaluated for the distortion pattern.
A diaphragm hat having a height of φ and a punch diameter of 87 mmφ and a height of 15 mm was prepared, and evaluated by the roughness of the flange portion (Rt: the greater the distortion pattern, the greater the Rt). Further, a deep-drawn cup was prepared, and the distortion pattern was visually inspected.

As is clear from Tables 2 and 3, Inventive Example No. 1 has appropriate precipitates, and is also excellent in strength, formability and distortion pattern of the cup side wall.
On the other hand, Comparative Examples No. 2 to No. 6 are all inferior in the distortion pattern of the cup side wall, and No. 2 and No. 3 are low in strength. Further, No. 4 to No. 6 are too high in strength and inferior in moldability.

[0029]

[Example 2] Aluminum alloy No. 1 in Table 1
Using the (invention material), cold rolling was carried out in the same process as in Example 1 to a thickness of 0.7 mm, and then Table 4

[Table 4] The heat treatment shown in FIG. After that, a cold rolled product plate having a thickness of 0.3 mm was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 5 and Table 5.

[Table 5]

[Table 6]

As is clear from Tables 5 and 6, the comparative examples manufactured under the conditions other than the manufacturing conditions of the present invention are satisfactory in strength and moldability, but in all cases, the strain pattern on the side wall of the cup is inferior. There is.

In each of the above examples, the evaluation criteria are a tensile strength of 30 kgf / mm ² or more and a limiting drawing ratio (LDR).
A pass of 1.90 or more, an Erichsen value of 4.3 mm or more, an Rt value of 5 μm or less, and a good cup sidewall distortion pattern were accepted.

[0032]

As described in detail above, according to the present invention,
Not only excellent moldability but also high strength of 30 kgf / mm ² or more, and further, it is possible to provide an aluminum hard metal plate excellent in the distortion pattern of the cup side wall, so that defects during molding can be reduced. , Has a great effect on improving productivity.

Claims (2)

[Claims] 1. Mn: 0.5% by weight (hereinafter the same)
1.5%, Mg: 0.5-1.5% and Cu: 0.05-0.5.
In an aluminum alloy containing 5% and the balance being Al and inevitable impurities, 0.5 μm or more of precipitates are 0.5 / μm ² or less, and 0.1 μm or less of 1 precipitate / An aluminum alloy hard plate with a high tensile strength of 30 kgf / mm ² or more and an excellent cup distortion pattern, characterized by having a distribution of at least μm ² . 2. The aluminum alloy ingot having the chemical composition according to claim 1, after the homogenizing heat treatment, hot rolling is finished at a plate thickness of 1.5 to 3.0 mm, and if necessary, cold cooling is performed. The solution heat treatment is performed at a temperature of 550 to 620 ° C. without or with hot rolling, followed by precipitation treatment at a temperature range of 150 to 250 ° C., and further cold rolling of 30% or more. A method of manufacturing an aluminum alloy hard plate having a high tensile strength of 30 kgf / mm ² or more and an excellent cup distortion pattern.