JPH05287425A - Soft aluminum alloy thin sheet excellent in formability and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture a soft Al allay thin sheet excellent in formability by subjecting the ingot of an Al alloy having a specified compsn. constituted of Fe, Si, Ti, B and Al to specified homogenizing treatment, hot rolling, cold rolling and final annealing. CONSTITUTION:The ingot of an Al alloy constituted of, by weight, 0.7 to 1.3% Fe and 0.3 to 0.8% Si as well as Fe>Si-+0.1%, 0.005 to 0.1% Ti and <=0.05% B and furthermore constituted of, at need, 0.01 to 0.2% Cu, and the balance Al with inevitable impurities is subjected to homogenizing treatment at 500 to 600 deg.C for 5 to 20hr. Next, hot rolling for this Al alloy is started at 460 to 550 deg.C, and after the hot rolling or in the process of cold rolling, process annealing is executed at 300 to 450 deg.C for 0.5 to 5hr. Moreover, the draft in the cold rolling after the process annealing is regulated to 70 to 90%, and after that, finial annealing is executed at 250 to 500 deg.C for 0.5 to 5hr. In this way, the objective soft Al alloy thin sheet for a low strength container having <=0.5mm sheet thickness, contg. compound grains with 1 to 20m maximum diameter at a distribution of 3X10<3> to 5X10<4> grains/mm<2> and excellent in formability can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging container in which a molded product is desired to have a thin wall thickness and low strength, for example, a container such as an automobile airbag canister which must be destroyed at the time of collision. The present invention provides an optimal thin plate and a manufacturing method thereof. Specifically, 0.5m
It is a soft material with a diameter of m or less, has excellent seizure resistance with the forming tool in press forming, and has fine earrings and crystal grains, so the container wall can be ironed at the same time as redrawing or drawing. The present invention relates to an optimal thin plate and a manufacturing method thereof for reducing the strength of a molded product (the cross-sectional hardness of the wall part after molding is about 60 or less in Hv).

[0002]

2. Description of the Related Art JI is used for forming aluminum alloy thin plates.
Industrial pure aluminum such as SA1100 and 1200, J
ISA3003 alloy, JISA3004 alloy, JISA
There are 5052 alloy and AA8011 alloy.

Conventionally, these alloys are thick plates exceeding 0.5 mm in order to be used in pots and other articles in soft tempering, and in the case of thin plates of 0.5 mm or less, the strength of molded products is emphasized. Therefore, it was used in a semi-hard to hard temper.

On the other hand, in the field of application of the present invention where the molded product is required to be thin and have low strength, JISA110
0,1200 industrial pure aluminum soft plates have been used.

When a thin plate is formed into a container, the depth cannot be obtained by a single press forming, so that the container wall is squeezed two or more times or at the same time the container wall is ironed to obtain a container. The soft plate of the 1100 and 1200 alloys is difficult to form due to seizure with the tool in the second or more machining, and the material is crushed due to the soft plate, resulting in poor yield and removal of defective materials. There was a problem that work was interrupted. Furthermore, since the ear rate exceeds 2% and is unstable, the shape of the molded product is apt to be distorted due to the softness and thin plate, and there is a problem of poor yield. 300
Although it is possible to mold a thin soft material of 3 alloys, 3004 alloys, and 5052 alloys, the hardness of the molded product is high and does not meet the purpose of the present invention, and the ear ratio cannot be stably obtained at 2% or less. There was a problem.

The term "baking" as used in the present invention means a phenomenon in which the surface of a molded product is scratched in a streak shape due to the adhesion between the die and the material during press working.

As described above, requirements for a soft thin plate for redrawing are that it has excellent seizure resistance with a tool, that the ear ratio is stable at 2% or less, and that there is no rough skin after molding. The average crystal grain size may be 50 μm or less so as to facilitate deep drawing, and a material satisfying all of these has been desired.

[0008]

DISCLOSURE OF THE INVENTION The present invention is to provide an aluminum alloy thin plate which does not cause seizure with a tool, has a small ear ratio and is stable, has no rough surface after molding, and is easily drawn deeply. To do.

[0009]

In order to solve the above-mentioned problems, as a result of intensive studies by the present inventors, the compound particles distributed in the material affect the seizure, and Al-Fe and Al- It has been found that by devising the particle size and distribution of the Fe-Si alloy, the particles can reduce friction between the die and the material and prevent seizure. Furthermore, by devising the manufacturing conditions, the ear ratio is stable at 2% or less, the crystal grain is fine with a size of 50 μm or less, and it is an optimal soft material excellent in moldability including a plurality of processes. Found to get. After all, the constitution of the present invention is a soft aluminum alloy thin plate excellent in formability as described in the claims and a manufacturing method thereof.

Hereinafter, each condition described in the claims will be described in detail.

Fe is an Al-Fe or Al-Fe-S which is effective for seizure resistance when it is used alone or together with Si.
The i compound is formed. Furthermore, it is an element that makes the crystal grains finer and improves the moldability. F for that
The amount of e is 0.7 to 1.3%. If it is less than 0.7%, not only is the amount of compound particles small and there is no effect on seizure resistance, but also the grain refining effect is not sufficient and molding processability cannot be improved. If it exceeds 1.3%, Al ₃ Fe will be produced during casting.
And a needle-like coarse compound is produced to deteriorate the moldability.

Si, in the coexistence with Fe, forms Al-Fe-Si compound particles effective for seizure resistance.
Further, it is an element that improves anisotropy and makes it easy to obtain a small ear rate, and is effective in stabilizing the ear rate. Therefore, the amount of Si is set to 0.3 to 0.8%. If it is less than 0.3%, not only is the amount of Al-Fe-Si compound particles small and there is no effect on seizure resistance, but it is difficult to obtain a small earing rate of 2% or less. If it exceeds 0.8%, the Al-Fe-Si compound particles become too coarse and become streaky defects on the surface of the thin plate, which impairs the appearance. The Fe content is made larger than the Si content + 0.1%. This is due to Al-Fe compound particles and Al-Fe-Si.
This is because many compound particles are dispersed. If this condition is not satisfied and the amount of Si increases, simple Si particles are generated, and the Al-Fe compound particles and Al-Fe-Si compound particles that are effective in seizure resistance decrease.
Cu is an element that improves moldability. Therefore, the amount of Cu is set to 0.01 to 0.2%. If it is less than 0.01%, the effect cannot be obtained. If it exceeds 0.2%, the corrosion resistance deteriorates.

Regarding Ti and B added for refining the ingot structure, Ti: 0.005 to 0.1
%, B: 0.05% or less. Ti content is 0.005%
If less than, there is no effect of refining the ingot structure, Al-F
A streak pattern is generated on the entire surface of the thin plate due to the coarse distribution of e and Al-Fe-Si compound particles. On the other hand, if it exceeds 0.1%, a coarse intermetallic compound of Al ₃ Ti is generated, so that a striped pattern is formed on the surface of the thin plate, which causes cracks during molding. B is an element that further promotes the effect of refining the ingot structure by coexisting with Ti. B amount is 0.05
If it exceeds 0.1%, a coarse intermetallic compound of TiB ₂ is produced, so that a striped pattern is formed on the surface of the thin plate, which causes cracks during molding.

The maximum grain size effective for seizure resistance is 1 to 20 μm. If it is less than 1 μm, there is no effect. When it exceeds 20 μm, streak-like defects are likely to occur on the surface of the thin plate, which is not preferable. The distribution of particles is 3 in area ratio.
× 10 ^{3 to} 5 × 10 ⁴ pieces / mm ² are preferable. 3 × 10 ³ pieces / m
When it is less than m ² , the number of particles is small and the seizure resistance is not effective. The effect saturates even if it exceeds 5 × 10 ⁴ pieces / mm ² .

Next, the manufacturing conditions will be described in detail.

The production conditions are regulated in order to obtain proper compound particles, 2% or less seizures, and 50 μm or less crystal grains within the above-mentioned component ranges.

In order to obtain the size and distribution of the compound particles which are effective in seizure resistance, it is necessary to regulate the homogenizing condition of the ingot and the hot rolling start temperature. These conditions also affect the ear rate and the crystal grains. The condition after hot rolling has a great influence on the ear ratio and the crystal grains, but has little influence on the target compound particles of 1 μm or more.

The ingot is homogenized at 500 to 600 ° C.
The condition is 5 to 20 hours.

If the temperature is less than 500 ° C. or less than 5 hours, the homogenization is insufficient and the distribution of the compound particles is non-uniform, and the area ratio of the Al—Fe—Si compound is 3 × 1.
It is not possible to obtain a distribution of 0 ^{3 to} 5 × 10 ⁴ pieces / mm ² . Furthermore, not only is it difficult to adjust the ear rate to 2% or less, but also the crystal grains tend to become coarse. 600 ° C
If it exceeds 1, the compound particles of 1 μm or more are easily infiltrated into the matrix, and the area ratio of the compound particles of 1 to 20 μm is less than 3 × 10 ³ particles / mm ^2, and the effect of the ear rate and the crystal grains is Saturate. Not only that, but also there is a risk of eutectic melting, which is not preferable. When it exceeds 20 hours, the effects of the compound particles, the ear ratio and the crystal grains are saturated and the cost of the heat treatment is increased, which is not preferable.

The starting temperature of hot rolling affects the compound particles of 1 μm or more and the grain refinement. A temperature of 460 to 550 [deg.] C. is suitable for obtaining an appropriate size and distribution of compound particles and an average crystal grain size of 50 [mu] m or less. If the temperature is lower than 460 ° C., fine precipitation is promoted to hinder the growth of compound particles during hot rolling, and the desired size distribution of 1 μm or more cannot be obtained, and fine crystal grains of 50 μm or less cannot be obtained. .. When the temperature exceeds 550 ° C, the effect on the compound particles is small, but the effect of refining recrystallization after final annealing is not exerted.

The intermediate annealing performed after the hot rolling or in the middle of the hot rolling causes the precipitation of Al-Fe-Si compound to cause the recrystallized grains in the subsequent final annealing of the cold rolled sheet. It is carried out to obtain a finer grain size and an ear rate of 2% or less. Since the precipitated compound particles here are fine particles of less than 1 μm, they do not affect the seizure resistance. The conditions therefor are 300 to 450 ° C. and 0.5 to 5 hours.
When the temperature is lower than 300 ° C. and higher than 450 ° C., or when the temperature is lower than 0.5 hour, precipitation in the intermediate annealing is insufficient and the effect cannot be obtained. If it exceeds 5 hours, the effect is saturated and the cost of heat treatment increases, which is not preferable.

The workability of cold rolling after the intermediate annealing is carried out in order to stably obtain the earring rate after the final annealing of 2% or less. The condition therefor is 70 to 90%. If this condition is not satisfied, the ear rate will exceed 2%.

The final annealing is carried out to recrystallize and soften, and to reduce the ear rate to 2% or less. The conditions therefor are 250 to 500 ° C. × 0.5 to 5 hours. If this condition is not satisfied, the ear rate will exceed 2%. Further, if the temperature is lower than 250 ° C, recrystallization is not sufficient and the state is semi-hard.

The present invention will be specifically described with reference to the following examples.

[0025]

【Example】

Example (1) Components An Al alloy containing the components shown in Table 1 was produced by DC casting, and a block having a thickness of 20 mm, a thickness of 100 mm, and a width of 100 mm was cut out and used as a test piece for rolling. After homogenizing treatment at 580 ° C. for 10 hours, it was heated to 540 ° C. and hot rolled to a thickness of 2 mm. After that, intermediate annealing was performed at 380 ° C. for 1 hour and cold rolling was performed to a thickness of 0.25 mm. The cold workability after the intermediate annealing is 87.5%. 350 ℃ × 1 on the thin plate
A final anneal of time was applied. Thus prepared 0.
Measurement of size and number of distribution of compound particles of 25 mm thick soft thin plate, redrawability, ear ratio, average crystal grain size, corrosion resistance test,
The appearance of the re-draw-formed cup was observed.

The size and distribution of the compound particles were measured on an electrolytically polished plate surface with an image analyzer LUZEX500 manufactured by Nireco.

In the redrawability test, redrawing was performed by the method shown in FIG. First, the blank plate 1 shown in (a) is drawn for the first time to form the first drawn container 2 as shown in (b), and then the drawing container 3 and the wrinkle retainer 4 are drawn as shown in (c). Then, redrawing was performed using the redrawing die 5 to form the redrawing container 6 as shown in (d). The limiting drawing ratio and the limiting total drawing ratio, which are the limits that do not crack during this drawing, were determined.

The ear rate was obtained by the following formula after squeezing the cup with a blank diameter of φ33 mm (flat head punch).

{(Mountain height)-(valley height)} /
[{(Height of peak) + (height of valley)} / 2] x 100 The average grain size is determined by electropolishing the plate surface, electrolyzing with Barker's solution to reveal the grain by polarization, and rolling direction. The width of the crystal grain in the direction perpendicular to was determined by the cutting method and taken as the average value.

Corrosion resistance was expressed by a three-stage evaluation as follows based on a comparison of the results obtained by spraying 5% saline at 35 ° C. for 100 hours on the basis of JIS Z2371 salt spray test method.

Equivalent to JIS A1050: ○ Slightly inferior to JIS A1050: △ Inferior to JIS A1050: × No. 1-No. 7 is Fe, Si,
The amounts of Cu, Ti and B are set near the lower limit or the upper limit within the claims. No. No. 5 alloy does not contain Cu, and the amount of Cu is an unavoidable amount of impurities. In each alloy, compound particles of 1 to 20 μm have a particle size of 3 × 10 ^3.
To 5 × 10 ⁴ cells / mm ² in and baking without limitation redrawing ratio is 1.5 or more, the limit total drawing ratio showed high aperture ratio 3.0 or more. The ear rate was 2% or less. Corrosion resistance is also JIS A1
It was equivalent to 050 industrial pure aluminum. The appearance of the cup was also good with no streak pattern. ,on the other hand,
No. 8 to No. 16 are comparative examples.

No. 8 has a Fe content below the lower limit of the claimed range. The number of compound particles falls below 3 × 10 ³ particles / mm ² and seizure occurs, resulting in poor redrawability. Ear rate exceeds 2%.

In No. 9, the amount of Fe exceeds the upper limit of the claimed range. Although the ear rate is small, it has a streak-like pattern due to coarse crystallized substances and is poor in redrawability.

In No. 10, the Si content + 0.1% is equivalent to the Fe content. The number of compound particles falls below 3 × 10 ³ particles / mm ² and seizure occurs, resulting in poor redrawability.

In No. 11, the amount of Si is below the lower limit of the claimed range. The number of compound particles falls below 3 × 10 ³ particles / mm ² and seizure occurs, resulting in poor redrawability. Ear rate exceeds 2%.

In No. 12, the Si amount exceeds the upper limit of the claimed range and the Si amount + 0.1% exceeds the Fe amount. The ear rate is high. Moreover, there are streaky patterns on the entire surface and the appearance is inferior.

In No. 13, the Cu content exceeds the upper limit of the claimed range. Inferior in corrosion resistance.

No. 14 has a Ti content below the lower limit of the claimed range. The crystal grains are coarse and the skin is rough.

In No. 15, the Ti amount exceeds the upper limit of the claimed range. The entire surface has streaky patterns and is inferior in appearance.

No. 16, the amount of B exceeds the upper limit of the claim. The entire surface has streaky patterns and is inferior in appearance.

As described above, when the components are out of the claimed ranges, any one of redrawability, ear ratio, corrosion resistance, and appearance of cup after drawing is inferior, which is not preferable as a soft thin plate of a molded product. (2) Manufacturing conditions DC ingots of No. 1 alloy (Cu-added material) and No. 5 (Cu-free material, Cu content is unavoidable impurity content level) in Table 1 were made to have the same dimensions as (1). It was cut out and manufactured into a 0.25 mm soft plate under the manufacturing conditions shown in Table 2. The results of the same tests as in (1) are shown in Table 3.

No. 17 to No. 22 were manufactured under the conditions within the scope of the claims of the present invention. The number of particles having a maximum diameter of 1 to 20 μm is 3 × 10 ^{3 to} 5 × 10 ⁴ particles / mm ² , the redrawability is good, the ear rate is 2%, and the appearance after cup drawing is also good.

On the other hand, No. 23-No. 32 is a comparative example. In comparison between No. 1 alloy and No. 5 alloy, there is a difference in the absolute value of the characteristic value, and although the Cu added material of No. 1 gives slightly better results, both alloys show the same tendency. ing.

No. 23 has an ingot homogenization treatment temperature lower than the claimed range. The ear rate is 2% or more, and the crystal grains are slightly large. Therefore, it is inferior in redrawability.

No. 24 has an ingot homogenization treatment temperature lower than the claimed range. This also has an ear ratio of 2% or more and a slightly large crystal grain. Therefore, it is inferior in redrawability.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

[Table 5]

[0051]

[Table 6]

In No. 25, the starting temperature of hot rolling is below the claimed range. The ear rate is 2% or more and the redrawability is poor.

Regarding No. 26 to No. 32 as well, since the conditions of the intermediate annealing to the final annealing do not satisfy the claims, the ear ratio or the crystal grain is large and the redrawability is inferior.

As described above, when the manufacturing conditions do not satisfy the scope of the claims of the present invention, the redrawability is poor and it is not preferable as a soft thin plate for molding.

[0055]

As described above, according to the soft aluminum alloy sheet of the present invention and the method for producing the same, continuous forming such as redrawability is excellent, and the ear rate is small, and the rough skin and streaks after forming are obtained. You can get a good appearance without defects,
It plays an important role industrially.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a step of deep drawing a soft aluminum alloy thin plate of the present invention.

[Explanation of symbols]

 1 blank plate 2 first draw container 3 redraw punch 4 wrinkle retainer 5 redraw die 6 redraw container

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shin Tsuchida 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industry Co., Ltd.

Claims (4)

[Claims] 1. Fe: 0.7 to 1.3% (weight%, the same applies hereinafter) Si: 0.3 to 0.8% (Fe)> (Si) + 0.1% Ti: 0.005 to 0 1% B: 0.05% or less An aluminum alloy consisting of the balance Al and unavoidable impurities, with a plate thickness of 0.5 mm or less and a maximum diameter of 1 to 20 μm.
And a distribution of 3 × 10 ^{3 to} 5 × 10 ⁴ particles / mm ² of compound particles, which is excellent in formability. 2. Fe: 0.7 to 1.3% (weight%, the same applies hereinafter) Si: 0.3 to 0.8% (Fe)> (Si) + 0.1% Ti: 0.005 to 0 1% B: 0.05% or less Homogenizing treatment of an aluminum alloy ingot composed of the balance Al and unavoidable impurities is performed at 500 to 600 ° C. for 5 to 20 hours, the hot rolling start temperature is 460 to 550 ° C. The intermediate annealing performed during the cold rolling after the hot rolling or after the hot rolling is 300 to 450 ° C. for 0.5 to 5 hours, the workability of the cold rolling after the intermediate annealing is 70 to 90%, and the cold rolling is performed. A method for producing a soft aluminum alloy thin plate having excellent formability, wherein the final annealing performed after rolling is 250 to 500 ° C x 0.5 to 5 hours. 3. Fe: 0.7 to 1.3% (weight%, the same applies hereinafter) Si: 0.3 to 0.8% (Fe)> (Si) + 0.1% Cu: 0.01 to 0 0.2% Ti: 0.005 to 0.1% B: 0.05% or less An aluminum alloy composed of the balance Al and unavoidable impurities, a plate thickness of 0.5 mm or less, and a maximum diameter of 1 to 20 μm.
And a distribution of 3 × 10 ^{3 to} 5 × 10 ⁴ particles / mm ² of compound particles, which is excellent in formability. 4. Fe: 0.7 to 1.3% (weight%, the same applies hereinafter) Si: 0.3 to 0.8% (Fe)> (Si) + 0.1% Cu: 0.01 to 0 0.2% Ti: 0.005 to 0.1% B: 0.05% or less A homogenizing treatment of an aluminum alloy ingot composed of the balance Al and unavoidable impurities is performed by hot rolling at 500 to 600 ° C. for 5 to 20 hours. The starting temperature of 460 to 550 ° C., the intermediate annealing performed during the hot rolling or during the cold rolling after the hot rolling is 300 to 450 ° C. × 0.5 to 5 hours, and the cold rolling after the intermediate annealing is performed. A method for producing a soft aluminum alloy sheet having excellent formability, wherein the workability is 70 to 90%, and the final annealing performed after cold rolling is 250 to 500 ° C x 0.5 to 5 hours.