JP2000001730A - Aluminum alloy sheet for can body, and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy sheet for can body, having high strength, reduced in earing, excellent in pitting corrosion resistance, ironing formability, etc., and capable of attaining reduction in the thickness and weight of DI cans in high yield. SOLUTION: The Al alloy sheet has a composition consisting of, by weight, >0.3-0.9% Si, 0.3-0.7% Fe, 0.8-1.4% Mn, 0.05-0.5% Cu, 0.8-1.4% Mg, >0.25-1.0% Zn, 0.01-0.1% Ti, and the balance Al with inevitable impurities, and further, an Mg2Si compound of 0.1-1 μm diameter is dispersed in the Al matrix by <=10000 pieces per square millimeter. In this Al alloy sheet for can body, ironing formability is improved by increasing the amounts of Si and Zn in the JIS 3004 alloy and hardening and refining an Fe-Mn compound by Si, pitting corrosion is improved by Zn, and further the improvement of strength and the prevention of earing are attained by controlling the number of precipitated Mg2Si compounds, and further, reduction in the thickness and weight of DI cans can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-piece DI having high strength, low ears, excellent pitting resistance and ironing formability.
The present invention relates to an aluminum alloy plate for a can body capable of realizing a thin and lightweight can and a method for producing the same.

[0002]

2. Description of the Related Art JIS 3004 alloys (Si0.3, Fe0.7, Cu0) which are excellent in formability of drawing, ironing, and flange (lid-tightened portion) required for can-making are used for Al alloy sheets for can bodies. .25, Mn
1.0-1.5, Mg 0.8-1.3, Zn 0.25 wt%), JIS 3104 alloy and the like are used. The aluminum alloy plate for the can body is, for example, homogenized into a JIS 3004 alloy ingot,
It is manufactured by subjecting it to hot rolling, annealing, and cold rolling (see JP-A-61-288055). By the way, in recent years, D
With the strong demand for thinner and lighter I-cans, Al alloy sheets for can bodies are required to have high strength and excellent formability. For example, a material obtained by improving JIS 3004 alloy (Japanese Patent Laid-Open No. 61-28)
No. 8055) has been proposed. However, any of these materials has a problem in that, when the strength is increased, seizure occurs during ironing and pitting tends to occur.

[0003]

SUMMARY OF THE INVENTION
The present inventors have conducted various studies on Al alloys for can bodies, and found that increasing the amount of Si in the JIS3004 alloy improves strength and ironing formability, and increasing the amount of Zn increases the amount of pores. We found that food could be reduced. However, ears (jagged edges at the end of the can) become high during ironing and the like, and the ears are trimmed, resulting in a new problem of lowering the production yield.

Therefore, the present inventors investigated the cause of the increase in ear height as Si was added, and found that the cause was that recrystallization was suppressed by the increase of Si.
It has been found that this can be promoted by specifying the size and number of the Mg ₂ Si compounds dispersed in the 1 alloy plate, and further research has been carried out to complete the present invention. The present invention relates to an aluminum alloy sheet for a can body, which is high in strength, has low ears, is excellent in pitting corrosion resistance, ironing formability, and the like, and can realize a thin and lightweight two-piece DI can and a method for producing the same.

[0005]

According to the first aspect of the present invention,
More than 0.3 wt% of Si and 0.9 wt% or less,
0.7 wt%, Mn 0.8-1.4 wt%, Cu 0.0
5 to 0.5 wt%, 0.8 to 1.4 wt% of Mg, 0.25 wt% to 1.0 wt% or less of Zn, 0.01 to 0.01 wt% of Ti
0.1 wt%, the balance being Al and unavoidable impurities, and having a diameter of 0.1 to 1 μm in the Al matrix.
An aluminum alloy plate for a can body, wherein 10000 or less ₂ Si compounds are dispersed per 1 mm ² .

According to a second aspect of the present invention, there is provided a semiconductor device comprising 0.3 wt% of Si.
Over 0.9 wt% or less, 0.3 to 0.7 wt% Fe, Mn
0.8-1.4 wt%, Cu 0.05-0.5 wt%,
0.8-1.4 wt% Mg, 0.25 wt% or more and 1.0 wt% or less Zn, 0.01-0.1 wt% Ti,
The remaining portion of the Al alloy ingot consisting of Al and inevitable impurities is subjected to a homogenization treatment, and then hot-rolled to a rolling end temperature of 30.
0 ° C. to 360 ° C. and then annealing treatment for 100
After heating to a temperature range of 380 ° C. to 520 ° C. at a heating rate of not less than 0 ° C./min and maintaining the temperature range for 0 second to 2 minutes,
2. The method for producing an aluminum alloy sheet for a can body according to claim 1, wherein the aluminum alloy sheet for a can body is cooled at a cooling rate of 100 ° C./min or more, then subjected to cold rolling, and then subjected to finish annealing as required. It is.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The alloy composition of the aluminum alloy sheet of the present invention will be described below. Si and Mg are Mg ₂ S
An i-compound is formed or a part of it is dissolved in an Al matrix, thereby contributing to an improvement in strength. In particular, Si transforms a later-described Fe—Mn-based compound into a hard and fine compound, and improves seizure resistance during ironing. The reason for specifying the Si content to be more than 0.3 wt% and 0.9 wt% or less is that if the content is less than 0.3 wt%, the effect cannot be sufficiently obtained.
If the content exceeds 0.9 wt%, a coarse Mg ₂ Si compound is precipitated after cold rolling, whereby the formability is reduced and pitting corrosion is liable to occur. The reason for defining the Mg content to be 0.8 to 1.4 wt% is that if the content is less than 0.8 wt%, the strength improving effect cannot be sufficiently obtained, and if the content exceeds 1.4 wt%, iron formability and the like are reduced. That's why. When both the contents of Si and Mg are large, the number of Mg ₂ Si increases and the ears become high without being sufficiently recrystallized after the annealing treatment.

[0008] Fe and Mn form an Fe-Mn-based compound to enhance flange formability. In the present invention, JIS30
The alloy contains more Si than the alloy No. 04, and the increment of Si hardens and refines the Fe-Mn-based compound as described above to improve the iron formability. Here, the content of Fe is 0.3 to 0.7 wt%, and the content of Mn is 0.8 to 1.4.
The reason for specifying the wt% is that if any of them is less than the lower limit, the flange formability and the iron formability are not sufficiently improved, and if the upper limit is exceeded, a primary crystal giant compound is formed and the overall formability is reduced.

[0009] Cu forms a solid solution in the Al matrix and contributes to improvement in strength. The reason for defining the content to be 0.05 to 0.5 wt% is that if the content is less than 0.05 wt%, the effect cannot be sufficiently obtained, and if it exceeds 0.5 wt%, the iron formability and the flange formability deteriorate. That's why.

[0010] Zn forms a solid solution in the Al matrix and contributes to improvement in strength. Further, in the present invention, Zn is contained more than the JIS 3004 alloy, and the increment of Zn is Mg ₂
The Si compound or the like is miniaturized to suppress the occurrence of pitting corrosion starting from the compound. The reason why the content is specified to be more than 0.25 wt% and not more than 1.0 wt% is that if the content is less than 0.25 wt%, the effect cannot be sufficiently obtained. Another reason is that the MgZn ₂ compound is generated and pitting corrosion easily occurs.

Ti makes the cast structure finer and suppresses the generation of streak patterns on the material surface. The content is 0.01-0.1
The reason for specifying the wt% is that if the amount is less than 0.01% by weight, the effect cannot be sufficiently obtained, and if the amount exceeds 0.1% by weight, a primary crystal giant compound is easily generated and the moldability is significantly impaired. 0.0001-0.01wt% B in addition to Ti
Addition further promotes micronization.

In the present invention, M having a diameter of 0.1 to 1 μm
The reason why the number of dispersed g ₂ Si compounds is defined to be 10,000 / mm ² or less is that the Mg ₂ Si compound is
If the number of pieces / mm ² or less, a completely recrystallized structure is obtained after the annealing treatment, and the ears can be kept low. If the number of the Mg ₂ Si compounds is suppressed to 10000 / mm ² or less, the decrease in the amount of solid solution of Mg becomes 0.09 wt% or less,
i The decrease in the amount of solid solution is suppressed to 0.05 wt% or less.
The strength improvement effect of g and Si does not need to be reduced so much.

Next, a method for manufacturing the aluminum alloy sheet of the present invention will be described. The alloy plate of the present invention is, for example, D
C casting, homogenization, hot rolling, annealing, cold rolling,
It is also manufactured by sequentially performing each step of finish annealing as required. Hereinafter, each step will be described.

In the homogenization treatment, the concentration distribution of the solute element is made uniform, the crystallized substance is re-dissolved, and an Fe-Mn compound useful for flange formability is produced. Homogenization treatment is 5
The condition of heating at 80 to 620 ° C. for 4 to 12 hours is preferable because the homogenization treatment is sufficiently performed and the productivity is not hindered.

In the present invention, hot rolling includes rough rolling and finishing.
Rolling, and after hot rolling Mg _TwoSi compound precipitates
And recrystallization occurs. Recrystallization rate at this time is 80%
With the above, a completely recrystallized structure is obtained after the next annealing treatment, and
Ears become low during molding. End temperature of the hot rolling
The reason why the temperature is specified at 300 to 360 ° C is less than 300 ° C.
In this case, a structure with a recrystallization rate of 80% or more cannot be obtained.
If it exceeds, the surface properties of the obtained Al alloy sheet will deteriorate.
It is.

The Mg ₂ Si compound precipitated after hot rolling partially re-dissolves in the Al matrix in the subsequent annealing treatment, and the re-solid solution causes M 2 having a size of 0.1 to 1 μm.
g ₂ Si is reduced to 10,000 or less per 1 mm ^2, recrystallization is promoted, and a completely recrystallized structure is obtained. The reason why the annealing treatment is performed at 380 to 520 ° C. for 0 second to 2 minutes and the heating and cooling rate is specified to be 100 ° C./min or more is that when the annealing treatment temperature is lower than 380 ° C., the Mg ₂ Si compound is re-used. Insufficient solid solution, 0.1 to 1 μm in diameter of Mg ₂ S
Since the i-compound is dispersed in excess of 10,000 particles / mm ² , a complete recrystallized structure cannot be obtained, and even if the annealing temperature exceeds 520 ° C or the holding time exceeds 2 minutes, the crystal grains become coarse and ironing is performed. If the heating rate or the cooling rate is less than 100 ° C./min, the productivity is reduced. In particular, if the cooling rate is less than 100 ° C./min, Mg ₂ S
This is because a large number of i-compounds are precipitated.

In the present invention, the cold rolling is performed to impart necessary strength by squeezing or the like. Cold rolling rate is 6
If it is less than 0%, sufficient strength cannot be obtained, and if it exceeds 90%, the ears become high due to ironing. Therefore, the cold rolling rate is 60-
90% is desirable.

In the present invention, after cold rolling, finish annealing is performed as necessary to recover elongation. This is desirably performed under conditions where the tensile strength after cold rolling is not impaired, for example, at a low temperature of 120 ° C. or lower and 3 hours or less.

[0019]

The present invention will be described below in detail with reference to examples. (Example 1) An Al alloy ingot having a composition shown in Table 1 (thickness: 50)
0 mm) at 600 ° C. for 6 hours, followed by hot rolling (rough rolling → finishing rolling) at a rolling end temperature of 330 ° C.
C. to form a hot-rolled material (hot-rolled coil) having a thickness of 2.2 mm. After cooling this hot-rolled material to room temperature, it is heated in a continuous annealing furnace for 4 hours.
An annealing treatment was performed at 00 ° C. for 0 second (air cooling immediately after reaching 400 ° C.). The heating rate or cooling rate in this annealing treatment was 850 ° C./min and 1000 ° C./min, respectively. After annealing, cold-rolled to a thickness of 0.3 mm (rolling rate 86.4%)
Then, finish annealing was performed at 115 ° C. for 2 hours to produce an Al alloy plate for a can body.

For each of the Al alloy plates obtained in Example 1, the ear ratio, tensile strength, moldability of the can, Mg ₂ S
The size and number of i-compounds and the occurrence of pitting corrosion were examined.
The ear ratio was determined by cutting out a disk having a diameter of 57 mm from the Al alloy plate and squeezing the disk with a punch having a diameter of 33 mm and a shoulder R of 2.5 mm with a clearance of 30%. It was expressed as a percentage (ear ratio). Tensile strength is the tensile strength (TS) according to JISZ2241.
And 0.2% proof stress (YS) were measured. Measurements were also made on those subjected to heat treatment under the conditions of baking paint (200 ° C. × 20 minutes). The moldability of the can was measured using a DI can body for carbonated beverages (inner diameter 66 mm, side wall thickness 103 μm, side wall thickness 165).
μm, an inner diameter of a neck portion of 57 mm, a number of steps of a neck portion of 4 steps, and a flange width of 2.2 mm) were manufactured in many cans, and the fracture rate, surface properties, and flange cracking at that time were examined. The size and number of the Mg ₂ Si compound were measured by TEM observation and image processing. The occurrence of pitting is 20 × 8 cut out from the side wall of the can.
A 0 mm test piece was treated with 1% citric acid + 0.1% Na at 40 ° C.
After immersing in a Cl solution for one week, the surface of the test piece was observed and examined. Samples with a pit depth of less than 20 μm were judged as good (○), and samples with a pit depth of more than 20 μm were judged as poor (×). Table 2 shows the results.

[0021]

[Table 1] (Note) Unit: wt%.

[0022]

[Table 2] (Note) Unit: wt%.

[0023]

[Table 3] (Note) MPa. The 45-degree ear, the higher the absolute value, the higher the ear. Fracture ratio ppm, properties: good, x burning occurred, crack: flange crack ppm.

[0024]

[Table 4] (Note) MPa. The 45-degree ear, the higher the absolute value, the higher the ear. Fracture ratio ppm, properties: good, x burning occurred, crack: flange crack ppm.

As is clear from Tables 3 and 4, the present invention example (N
o.A to D) all had high tensile strength, low ear ratio (within 2.5%), good moldability of the can, and no pitting. On the other hand, in Comparative Examples (Nos. E to Q), any one of the alloy elements was out of the range specified in the present invention, so that any one of the above characteristics was deteriorated and lacked practicality. Especially No.F is M
The ear ratio was extremely high due to the large number of g ₂ Si.

(Example 2) An ingot (thickness: 500 mm) of the alloy B having the composition specified in the present invention shown in Example 1 was subjected to a homogenization treatment at 600 ° C for 6 hours and then hot-rolled to a thickness of 2 mm. .2
mm hot-rolled material (hot-rolled coil), and after the hot-rolled material is cooled to room temperature, is annealed using a continuous annealing furnace, and then cold-rolled to a thickness of 0.3 mm (rolling ratio: 86.000 mm). 4%)
Then, finish annealing was performed at 115 ° C. for 2 hours to produce an Al alloy plate for a can body. The hot rolling end temperature and annealing conditions were variously changed as shown in Table 5. Various characteristics of the alloy plate thus obtained were investigated in the same manner as in Example 1. Table 6 shows the results.

[0027]

[Table 5]

[0028]

[Table 6] (Note) MPa. The 45-degree ear, the higher the absolute value, the higher the ear. Fracture ratio ppm, properties: good, x burning occurred, crack: flange crack ppm.

As is clear from Table 6, the present invention example (No. 1)
4) have high tensile strength and low ear ratio (2.5%).
%), The moldability of the can was good, and no pitting occurred. In contrast, since No.5 lower end of hot rolling temperature of the comparative example, since No.7 is annealing temperature is low, No.10, because the heating rate and the cooling rate is low, both Mg ₂ Si The number of compounds increased, resulting in a higher ear rate and lower tensile strength. No. 6 has a high hot rolling end temperature,
In the case of o.8, the annealing temperature was high, and in the case of No.9, the annealing time was long, and in each case, the crystal grains became coarse and the formability deteriorated.

[0030]

As described above, the can body A according to the present invention is used.
1 alloy plate increases the amount of Si and Zn of the JIS 3004 alloy, hardens and refines the Fe-Mn-based compound by the Si to improve ironing formability, improves the pitting corrosion by the Zn, and further improves the Mg ₂ Si compound. The number of precipitates is regulated to improve the strength and suppress the generation of ears, so that the DI can can be made thinner and lighter. Further, the Al alloy plate can be easily manufactured by an ordinary method in which a hot rolling end temperature and annealing conditions are specified.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference)

Claims (2)

[Claims] Claims 1. An alloy containing Si in an amount of more than 0.3 wt% and not more than 0.9 wt%.
0.3 to 0.7 wt% of Fe and 0.8 to 1.4 wt% of Mn
%, 0.05 to 0.5% by weight of Cu, and 0.8 to 1% of Mg.
4 wt%, Zn over 0.25 wt% and 1.0 wt% or less, Ti
0.01 to 0.1 wt%, the balance being Al and unavoidable impurities, and having a diameter of 0.1 to 0.1 in the Al matrix.
1 μm of Mg ₂ Si compound is 10000 / mm ²
An aluminum alloy plate for a can body, which is dispersed in pieces. 2. The method according to claim 1, wherein the content of Si is more than 0.3 wt% and 0.9 wt% or less;
0.3 to 0.7 wt% of Fe and 0.8 to 1.4 wt% of Mn
%, 0.05 to 0.5% by weight of Cu, and 0.8 to 1% of Mg.
4 wt%, Zn over 0.25 wt% and 1.0 wt% or less, Ti
, A homogenization treatment is applied to an Al alloy ingot consisting of Al and inevitable impurities, and hot rolling is performed at a rolling end temperature of 300 ° C to 360 ° C. The temperature of the annealing treatment is raised to a temperature range of 380 ° C. to 520 ° C. at a heating rate of 100 ° C./min or more, and maintained at the above temperature range for 0 second to 2 minutes, and then cooled at a cooling rate of 100 ° C./min or more. 2. The method for producing an aluminum alloy sheet for a can body according to claim 1, wherein the aluminum alloy sheet is subjected to cold rolling, followed by finish annealing as necessary.