JPH11140576A - Aluminum alloy sheet for can body minimal in dispersion of flange length and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an aluminum alloy sheet for can body, minimal in dispersion of flange length. SOLUTION: This Al alloy sheet has a composition consisting of, by weight, 0.25-0.35% Si, 0.30-0.50% Fe, 0.1-0.25% Cu, 0.9-1.2% Mn, 0.9-1.4% Mg, further 0.005-0.05% Ti independently or in combination with 0.0001-0.01% B, and the balance Al with inevitable impurities. In this Al alloy sheet, electric conductivity is 38-46% IACS, and earing after necking is 45 deg. earing and earing rate is <=0.05%. This Al alloy sheet can easily be produced by successively subjecting an ingot of Al alloy of the above composition to respective stages of (1) homogenizing annealing, (2) hot roughing, (3) hot finish rolling, (4) process annealing, (5) cold rolling, and (6) finish annealing while properly selecting temp. conditions, etc., in respective stages, where respective stages of (1), (2), (3), and (5) are essential stages and respective stages of (4) and (6) are selective stages.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy sheet for a can body having a small variation in flange length and a method for producing the same.

[0002]

2. Description of the Related Art Aluminum alloy sheets for can bodies such as beverage cans are usually manufactured by sequentially performing homogenized annealing, hot rolling, cold rolling, annealing, and cold rolling on a JIS-3004 alloy ingot. You. Finish annealing, degreasing and washing as needed
Coating lubricating oil is applied. Incidentally, the alloy plate has a problem of ear ratio (ratio of height difference (ear) between the height of the convex portion and the concave portion generated at the peripheral portion when the rolled disk is squeezed into a cup shape to the cup height). That is, if the ear ratio is large, (1) pinholes or tear-off occur due to chips peeling from the tip of the ear at the time of forming the cup, (2) dimensional accuracy of the can after flange forming is reduced, (3) can body There is a problem that it is necessary to increase the amount of trimming after molding, and (4) it is not possible to completely remove the concave portion at the periphery of the can even by trimming. With regard to this ear ratio, ears are generated even after necking due to recent reduction in diameter of cans, and the flange length varies due to the ears in subsequent flange processing, so that the can lid can not be properly tightened. A new problem has arisen. For this reason, an alloy sheet having a small ear ratio even after necking, that is, an alloy sheet having a small variation in flange length has been required.

Incidentally, the magnitude of the ear ratio of an alloy sheet is affected by its crystallographic anisotropy, and the recrystallized texture component (recrystallized grains having a cubic orientation) formed after completion of hot rolling or during annealing. : Mainly 0 ° -90 ° ears) and a rolled texture component formed by cold rolling (R-oriented recrystallized grains: 45 ° ears)
Becomes larger when it is shifted to one side, and becomes smaller when it is balanced. The recrystallized grains include subcrystal grains.

[0004] In recent years, in order to increase the strength of the can by increasing the cold working rate in response to the thinning of the can body,
The rolling texture component tends to increase. For this reason, there has been proposed a method in which hot rolling conditions are strictly defined and cubic orientation recrystallized grains are preferentially grown (Japanese Patent Laid-Open No. 4-22).
No. 8551, JP-A-6-158244). However, with the recent reduction in the diameter of cans, it has become strictly required for users to reduce the variation in flange length, and if only hot rolling conditions were specified, it would be necessary to reduce the variation in flange length. It's getting harder.

[0005]

SUMMARY OF THE INVENTION
The present inventors have studied methods for increasing the cubic orientation recrystallized grains, and among them, the self-heating or annealing heating of the coil after hot rolling causes the recrystallized grains of the R orientation to grow from the precipitate as a starting point. It was found that this hindered the growth of recrystallized grains in the cubic orientation, and furthermore, the precipitates were difficult to precipitate, and the homogenizing annealing conditions, hot rolling conditions, intermediate annealing conditions, etc. The invention has been completed. An object of the present invention is to provide an aluminum alloy plate for a can body having a small variation in flange length and a method for producing the same.

[0006]

According to the first aspect of the present invention,
Si 0.25 to 0.35 wt%, Fe 0.30 to 0.50
wt%, Cu 0.1 to 0.25 wt%, Mn 0.9 to 1.2
wt%, Mg 0.9 to 1.4 wt%, and further Ti0.005
-0.05wt% alone or B0.0001-0.0
1% by weight, the balance being Al and inevitable impurities, a conductivity of 38 to 46% IACS, a 45 ° ear after necking, and an ear rate of 0.05% or less. This is an aluminum alloy plate for a can body having a small variation in length.

The invention according to claim 2 is characterized in that Si 0.25
0.35 wt%, Fe 0.30 to 0.50 wt%, Cu0.
1 to 0.25 wt%, Mn 0.9 to 1.2 wt%, Mg0.
9 to 1.4 wt%, and 0.005 to 0.05 wt% Ti
Annealing, Hot rough rolling, Hot finishing rolling, Intermediate annealing, Cold annealing Rolling, finish annealing each process, the above, each process is an essential process,
A method of manufacturing an aluminum alloy plate to be sequentially performed by selecting each step as a selection step, wherein homogenizing annealing is performed at 580 to 61
After holding at 5 ° C for 4 hours or more, 550 ° C to 400 ° C
The temperature range up to 20 ° C./hour is cooled and applied, and hot rough rolling is started by reheating at the same temperature after homogenizing annealing or once at 30 ° C./hour after cooling. The hot finish rolling is started within 5 minutes after the completion of the hot rough rolling, and the total rolling ratio is set to 8 using a tandem type rolling mill having 3 or more stands.
0% or more, the finished plate thickness is 1.8 to 3.0 mm, the finished temperature is 310 to 350 ° C., and the intermediate annealing is heated at a rate of 100 ° C./min or more using a continuous annealing furnace to 400 to 300 ° C./min.
After holding at 460 ° C. for 0 to 120 seconds, it is cooled to 70 ° C. or less at a rate of 100 ° C./min or more, cold-rolled at a rolling reduction of 80 to 90%, and finish-annealed to 100 to 15%.
The method for producing an aluminum alloy plate for a can body having a small variation in flange length according to claim 1, wherein the method is performed while maintaining the temperature at 0 ° C.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention suppresses the precipitation of precipitates that inhibit the growth of recrystallized texture components (mainly 0 ° -90 ° ears), thereby reducing the ear ratio after necking. In an aluminum alloy plate in which the variation in flange length after flanging is reduced, the number density of precipitates (the number of precipitates per unit volume) is adjusted by using the conductivity having an index proportional to the number density of precipitates as an index. In the present invention, the reason why the conductivity of the aluminum alloy plate is limited to 38 to 46% IACS is that the conductivity increases beyond 46% IACS, the number density of the precipitate increases, that is, the solid solution of alloy elements such as Si and Cu. If the amount is small, these precipitates hinder the growth of cubic recrystallized grains at the time of annealing, and the variation in the ear ratio after necking and the flange length after flanging increase. When the number density of precipitates becomes lower as the conductivity becomes lower than 38% IACS, that is, when Si or Cu
If the amount of alloying elements such as alloying elements increases, the solid-solving elements precipitate in a large amount in the subsequent baking step, and the flange formability deteriorates. The reason why the ear ratio after necking is limited to 0.05% or less is that if the ear ratio exceeds 0.05%, the can lid cannot be properly tightened.

Next, the alloy components of the aluminum alloy sheet of the present invention will be described. Si causes a phase transformation in the Al-Mn-Fe-based crystallized product, forms an Al-Mn-Fe-Si-based precipitate, increases its hardness, and contributes to improvement in ironing workability. The reason for limiting the Si content to 0.25 to 0.35 wt% is that if the content is less than 0.25 wt%, the effect cannot be sufficiently obtained. This is because ironing workability is reduced.

[0010] Fe promotes crystallization of Mn and uniforms its distribution to improve DI formability. The reason for limiting the content of Fe to 0.30 to 0.50 wt% is as follows.
If it is less than 0.30 wt%, the effect cannot be sufficiently obtained.
If the content exceeds 50% by weight, the above-mentioned giant primary crystal compound of the Al-Mn-Fe system is likely to be generated. The desirable content of Fe is 0.35 to 0.45 wt%.

Cu contributes to improving the strength of the bottom of the can. Cu
The reason why the content of is limited to 0.1 to 0.25 wt% is as follows.
If the content is less than 0.1 wt%, the strength is insufficient, and sufficient pressure resistance cannot be obtained by DI molding. If the content exceeds 0.25 wt%, work hardening becomes large and ironing workability is reduced.

Mn contributes to improvement of strength and DI formability. The reason that Mn improves DI formability is that Mn has an Al-Mn-based, Al-Mn-Fe-based,
This is for forming a crystallized substance such as an Al-Mn-Fe-Si system. Emulsion-type lubricants are usually used for DI molding, but this alone is insufficient for lubrication, and build-up due to adhesion between the alloy mold and the mold occurs, causing abrasion or baking called galling or scoring. May occur. When an appropriate amount of Mn is contained, the build-up does not occur. Mn content of 0.9 to 1.2
The reason for limiting to wt% is that if it is less than 0.9 wt%, the DI moldability is not sufficiently improved and the strength is insufficient, and if it exceeds 1.2 wt%, the DI moldability and strength improvement effects are saturated, and as described above. At the time of melting and casting, a large Al-Mn-Fe primary crystal compound having a diameter of about several mm is sometimes easily generated, which remains even after rolling and causes cracks and pinholes during DI molding. In order to generate it. The desirable content of Mn is 1.0 to 1.2 wt%.

Mg contributes to strength improvement, and is particularly effective for improving the strength of the bottom of the can. The content of Mg is 0.9 to 1.4 wt.
The reason is that the effect is not sufficiently obtained if the content is less than 0.9% by weight, and if the content exceeds 1.4% by weight, work hardening is apt to occur, and the frequency of cracking during ironing during DI molding becomes high. It is. The optimum content of Mg, which provides a good balance between strength and DI formability, varies slightly depending on the amount of other elements added and manufacturing conditions, but is 1.0 to 1.35 wt%, particularly 1.1 to 1.0 wt%.
1.3 wt%.

[0014] Ti, or Ti and B, uniformly refine the crystal grains of the ingot to improve workability and formability. Ti
The reason for limiting the content to 0.005 to 0.05 wt% is that if the content is less than 0.005 wt%, the ingot crystal grains are not sufficiently refined uniformly, and if the content exceeds 0.05 wt%, Al-
This is because a large Ti-based twin compound is likely to be generated.
This giant twin compound remains even after rolling and causes cracks and pinholes during DI molding. B promotes the effect of Ti. If B is less than 0.0001% by weight, the effect cannot be sufficiently obtained. If B exceeds 0.01% by weight, a Ti-B-based giant twin compound is liable to be generated at the time of melting and casting, and the harmful effect of the giant twin compound described above. Occurs. The impurity is Zn.
3 wt% or less, Cr is 0.3 wt% or less, Zr is 0.1 wt%
Hereinafter, if V is 0.1 wt% or less, there is no problem even if V is contained without impairing the properties of the alloy sheet of the present invention.

A second aspect of the present invention is the method for producing an alloy sheet according to the first aspect of the present invention, wherein the number density of precipitates that inhibit the growth of recrystallized grains in cubic orientation is determined by homogenizing annealing conditions, hot rolling conditions, By selecting intermediate annealing conditions and the like, it is possible to manufacture an alloy sheet in which the variation in the flange length is reduced by reducing it. The number density of the precipitate is adjusted using conductivity as an index.

In the present invention, an aluminum alloy having a predetermined composition is formed into an ingot by, for example, a DC casting method (semi-continuous casting method), and the ingot is subjected to homogenization annealing to homogenize the distribution of alloy elements. The reason for holding at 580 to 615 ° C for 4 hours or more in the homogenization annealing is that the homogenization cannot be performed sufficiently even at less than 580 ° C or less than 4 hours, and when the temperature exceeds 615 ° C, the ingot surface may swell. It is. The most desirable holding condition in consideration of productivity is 590 to 610 ° C. for 6 to 12 hours. After cooling under the above conditions, 55
The temperature range in which alloying elements at 0 ° C to 400 ° C are likely to precipitate is 2
Al-Mn-F is rapidly cooled at a rate of 0 ° C / hour or more.
This is for suppressing the precipitation of e-Si-based compounds (precipitates) and the like. If the cooling rate is 20 ° C./hour or more, precipitation of alloy elements cannot be sufficiently suppressed.

In the present invention, a portion where strain serving as a recrystallization nucleus is concentrated in a matrix, that is, a transition band, by hot rough rolling and hot finish rolling after homogenizing annealing.
Is formed, and at the same time, a large amount of strain serving as a driving force for recrystallized grain growth is accumulated. By doing so, a structure in which cubic orientation recrystallized grains have priority is obtained.

In the present invention, hot rough rolling is desirably performed by utilizing the self-heating of the ingot after homogenizing annealing, because the number density of precipitates is reduced, and time and heating costs can be reduced.
In the case of cooling and reheating once, rapid heating is performed at a rate of 30 ° C./hour or more. If the reheating is performed at a speed lower than the above-mentioned rate, the number density of the precipitates of the alloy element increases and the variation in the flange length increases. The hot rough rolling is desirably performed at a temperature of 400 to 550 ° C. If the temperature is lower than 400 ° C., the number density of precipitates increases sharply and the growth of cubic recrystallized grains is suppressed. If the temperature exceeds 550 ° C., the surface of the hot-rolled sheet is oxidized or the recrystallized grains are coarsened to formability. May decrease.

In the present invention, the hot rough rolling end temperature is 4
The reason for limiting the temperature to 00 to 480 ° C is that if the temperature is lower than 400 ° C,
When the number density of precipitates increases rapidly, the growth of cubic orientation recrystallized grains is suppressed, and the rolling temperature is lowered in the next hot finish rolling to cause edge cracking. When the temperature exceeds 480 ° C, the next hot finishing is performed. This is because, during rolling, the strain which is the driving force for the cubic orientation recrystallized grains is not sufficiently accumulated. The reason why the time from the hot rough rolling to the start of the hot finish rolling is limited to 5 minutes or less is that if it exceeds 5 minutes, the strain accumulated in the hot rough rolling is recovered. A particularly desirable hot rough rolling end temperature is 400 to 450 ° C., and a time from the end of the hot rough rolling to the start of the hot finish rolling is within 3 minutes.

In the present invention, in the hot finish rolling, the alloy plate is finished to a predetermined size, and the structure after the hot finish rolling is made into a recrystallized structure by self-heating. The reason for using a tandem hot rolling mill having three or more stands in this hot finish rolling step is that if the number of stands is less than three, the rolling ratio per stand increases, and the surface properties of the hot rolled sheet are maintained. This is because it is difficult to accumulate distortion. The reason why the total rolling reduction in hot finish rolling is 80% or more is 80%
If it is less than 3, the accumulation of strain is insufficient, and the driving force for obtaining cubic orientation recrystallized grains during coil-up or annealing after hot finish rolling is insufficient, and the ear ratio increases. The reason for limiting the end plate thickness to 1.8 to 3.0 mm is as follows.
If the thickness is less than 1.8 mm, the surface properties (such as seizure and rough surface) and the thickness profile of the hot-rolled sheet are deteriorated. If the thickness exceeds 3.0 mm, cold rolling to the final thickness (0.28 to 0.35 mm) is performed. This is because the ratio increases, the recrystallized grains in the R direction increase, and the variation in the flange length increases. Further, the reason why the rolling end temperature in the hot finish rolling is limited to 310 to 350 ° C. is that if the temperature is less than 310 ° C., the recrystallization rate after cooling to room temperature becomes insufficient, and the recrystallized grains in the cubic orientation become insufficient, and 35%.
If the temperature exceeds 0 ° C., seizure or surface roughness occurs, and the surface properties of the hot-rolled sheet deteriorate. According to experiments by the present inventors, the recrystallization rate is desirably 85% or more. Recrystallization rate of 85
%, The material is annealed and then completely recrystallized.
It is difficult to increase only the cubic orientation recrystallized grains because the R orientation recrystallized grains also grow during annealing.

After the hot finish rolling, intermediate annealing is performed as necessary. The reason for performing the intermediate annealing while maintaining the temperature range of 400 to 460 ° C. for 0 to 120 seconds is that a complete recrystallized structure cannot be obtained at a temperature lower than 400 ° C. If the temperature exceeds 460 ° C. or exceeds 120 seconds, a large amount of precipitates such as Cu and Si re-dissolve in a solid solution, which precipitates at the time of baking for coating to lower the flange formability. The holding time of 0 second means cooling immediately after reaching the target temperature. The reason for limiting both the heating rate and the cooling rate to 100 ° C./min or more is that in any case, Cu and S
This is because i precipitates and sufficient strength cannot be obtained in the next cold rolling step. Particularly in the case of cooling, more rapid cooling is desirable because precipitation is easy.

In the present invention, cold rolling provides the necessary strength as a can body. The reason why the rolling reduction in the cold rolling is limited to 80 to 90% is that if it is less than 80%, the pressure resistance of the obtained alloy sheet is insufficient, and if it exceeds 90%, the DI is too high.
This is because the 45 ° ear ratio at the time of molding becomes large and the strength becomes too high, so that cupping cracks and can bottom cracks frequently occur during DI moldability. Finished thickness in cold rolling is
Usually, it is 0.28 to 0.35 mm.

In the present invention, after cold rolling, finish annealing is performed as necessary. The work structure is recovered by this finish annealing,
DI moldability and can bottom moldability are improved. Finish annealing temperature 1
The reason for limiting the temperature to 00 to 150 ° C. is that if the temperature is lower than 100 ° C., the recovery effect cannot be sufficiently obtained, and if the temperature exceeds 150 ° C., solid solution elements are excessively precipitated (the electrical conductivity exceeds 46%). And the flange formability is reduced. A particularly desirable finish annealing temperature is 115 to 150 ° C. The finish annealing time is desirably 4 hours or less, and if it exceeds 4 hours, solid solution elements are precipitated and DI formability decreases. In particular, 1 to 3 hours is desirable.

[0024]

The present invention will be described below in detail with reference to examples. (Example 1) An aluminum alloy having the composition of the present invention shown in Table 1 was melted and cast by a conventional method to form a slab (ingot) having a thickness of 500 mm. This was homogenized for 6 hours, then allowed to cool to room temperature at a cooling rate of 80 ° C./hour, then reheated to 530 ° C. at a temperature increasing rate of 50 ° C./hour, and hot-rolled to a thickness of 30 mm. Hot rough rolling end temperature is 420 ° C
Three minutes later (the recrystallization rate at this time was 5%), hot finish rolling was started using a rolling machine with four stands, and the thickness was 2.2 mm (total rolling reduction in finish rolling: 92). .7%). The finishing temperature of the hot finish rolling was 320 ° C., and the recrystallization rate of the hot-rolled material was 100%. After the completion of the hot rolling, the steel sheet was annealed at 400 ° C. for 0 second (air cooling immediately after reaching 400 ° C.) in a continuous annealing furnace. The heating rate at this time is 850
° C / min and the cooling rate was 1000 ° C / min. Next, cold rolling is performed to a sheet thickness of 0.3 mm by a conventional method (cold rolling ratio: 8).
7.5%), followed by finish annealing at 115 ° C. for 2 hours to produce an aluminum alloy plate for a can body. When the conductivity of this alloy plate was measured, all were 41-46% I.
It was within the range of ACS. The recrystallization rate is a cross-sectional area ratio occupied by recrystallized grains in a cross section of the hot-rolled sheet.

Comparative Example 1 An aluminum alloy plate for a can body was manufactured in the same manner as in Example 1 except that an aluminum alloy having the composition shown in Table 1 was used.

With respect to the alloy plate thus obtained,
The tensile strength, DI moldability, ear ratio after necking, and flange moldability were investigated. The tensile strength is set at 200 ° C for the alloy plate.
For 20 minutes (under the conditions of baking paint), and the tensile strength (TS) and 0.2% proof stress (YS) before and after heating were measured. DI
The moldability was investigated by DI molding into a can body for a carbonated drink (inner diameter 66 mmφ, side wall thickness 103 μm, side wall tip thickness 165 μm). The necking ear ratio was measured at 200 ° C for 20 minutes after trimming and washing the DI can body,
Next, necking was performed, and the ear ratio of the opening was measured. The flange formability is determined by pushing a conical jig at an angle of 90 ° until a flange crack occurs, measuring the diameter D (mm) of the opening when the crack occurs, and substituting this into the following formula. The critical increase rate P of the diameter of the part was obtained and evaluated. P = [(D−d) / d] × 100%. (Where d is the inner diameter of the opening after necking, mm).
Table 2 shows the results. The evaluation criteria were as follows: the ear ratio after necking was 0.05% or less, the proof stress after heat treatment (200 ° C. × 20 minutes) was 250 MPa or more, and the marginal increase rate of the diameter in flange forming was 15% or more. 45 ears after necking
° For ears with an ear ratio of 0.05% or less, the variation in flange length is small and the can lid can be tightened without any problem.

[0027]

[Table 1]

[0028]

[Table 2]

As is clear from Table 2, the present invention examples (No.
-D) are 45 ° ears after necking and an ear rate of 0.0
It was as low as 5% or less, and the marginal increase rate P of the diameter in flange forming was as large as 15% or more, and the flange formability was good. The proof stress (YS) after heating at 200 ° C. for 20 minutes (paint baking conditions) was 250 MPa or more, the pressure resistance at the bottom of the can was satisfactory, and the DI moldability was good. In contrast,
In Comparative Examples Nos. E and F, both of which had a large amount of Mg or Mn, the tensile strength was increased by baking heat at 200 ° C. for 20 minutes.
There has occurred. No. G has a large solid solution amount of Si and Cu,
This was precipitated at the time of paint baking, resulting in poor flange formability. In No. H, the strength was reduced because the amount of added Mg was small. N
In the case of o.I, baking occurred in DI molding because the amount of Mn added was small. In No. J, the strength was reduced because the added amounts of Cu and Si were small.

(Example 2) No. A aluminum alloy shown in Table 1 was melt-cast by a conventional method to form an ingot (slab) having a thickness of 500 mm, and the slab was face-cut to a thickness of 490 mm. This was subjected to homogenization annealing, cooling, heat treatment, hot rough rolling and finish rolling in this order to obtain a hot rolled coil. The hot-rolled coil was cooled to room temperature, and then subjected to intermediate annealing or cold-rolled by an ordinary method without intermediate annealing to produce an aluminum alloy sheet. Manufacturing conditions such as homogenization annealing, hot rolling, annealing, and cold rolling were variously changed within the range defined in claim 2 of the present invention as shown in Table 3.

Comparative Example 2 An aluminum alloy plate was manufactured in the same manner as in Example 2 except that the manufacturing conditions were out of the range defined in claim 2 of the present invention shown in Table 4.

For each of the alloy sheets thus obtained, the tensile strength, DI formability, ear ratio after necking, and flange formability were examined in the same manner as in Example 1.
The results are shown in Tables 5 and 6. The evaluation criteria were the same as in Example 1.

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

[Table 5]

[0036]

[Table 6]

As is clear from Tables 5 and 6, in each of the inventive examples (Nos. 1 to 10), the ear ratio after necking was 0.0%.
It was as low as 5% or less, and the flange formability was good. In addition, the strength (proof stress) after heat treatment equivalent to baking is 250 M
At a pressure of Pa or more, the strength of the bottom of the can was at a level without any problem, and the DI moldability was also good. In contrast, the comparative example
In No. 11, since the homogenization annealing temperature was high, swelling occurred on the surface of the ingot, and the surface properties after finish rolling were deteriorated. No.12
No. 13 had a low homogenizing annealing temperature, and No. 13 had a short homogenizing annealing holding time, so that homogenization was insufficient in each case, many fine precipitates were generated, and the ear ratio after necking was high. No.1
Nos. 4, 15 deviated from the cooling and heating conditions after the homogenization annealing of the present invention, and the cooling rate and the heating rate were slow, so that the number density of the precipitates increased, and the ear ratio after necking exceeded the reference value. In No. 16, the rough rolling end temperature was low, so that the number density of precipitates increased sharply, and the finish rolling start temperature was low, so that edge cracking occurred during finish rolling. In Nos. 17 and 18, the rough rolling end temperature was high and the time from the end of rough rolling to the start of finish rolling was long, so the strain accumulated in rough rolling recovered (recrystallization driving force), and the cube after finishing rolling was finished. The orientation recrystallized grains did not grow preferentially, and the ear ratio after necking exceeded the reference value. In No. 19, the total rolling reduction in finish rolling was small, the accumulation of strain was insufficient, and the ear ratio after necking exceeded the reference value. In No. 20, the finished plate thickness was small, seizure occurred after finish rolling, and the surface of the can was scratched when formed into a can. In No. 21, the finished plate thickness was large, so that the cold rolling reduction was high, drawing cracks were generated by DI molding, and the ear ratio after necking exceeded the reference value. In No.22, the finish rolling end temperature was too low, so recrystallization did not progress much during coil-up after finish rolling, and the growth of cubic orientation was small even after annealing, and the ear rate after necking exceeded the reference value. . No.23
Since the finish rolling end temperature was high, seizure occurred. N
In the case of o.24, the intermediate annealing temperature was high, so that heat softening by baking at 200 ° C. for 20 minutes did not occur and the flange formability was poor.
In No. 25, since the cold rolling reduction was high, draw cracking occurred in DI molding, and the ear ratio after necking also exceeded the reference value. N
In o.26, the strength (proof strength before baking) was increased due to precipitation due to high final annealing conditions, and iron cracks occurred.

[0038]

As described above, the aluminum alloy sheet for a can body according to the present invention has a small variation in flange length, can perform good winding of a can lid, and has tensile strength, DI formability, and flange forming. It has characteristics such as properties for a can body. Further, the aluminum alloy sheet for a can body of the present invention can be easily manufactured by a conventional method by limiting the homogenizing annealing conditions and the like. Therefore, an industrially remarkable effect is achieved.

────────────────────────────────────────────────── ⁶ Continuation of the front page (51) Int.Cl.

Claims (2)

[Claims] 1. The method according to claim 1, wherein the content of Si is 0.25 to 0.35 wt%,
30 to 0.50 wt%, Cu 0.1 to 0.25 wt%, Mn
0.9 to 1.2 wt%, Mg 0.9 to 1.4 wt%, and Ti 0.005 to 0.05 wt% alone or B0.0
001-0.01 wt%, the balance being Al and unavoidable impurities, having a conductivity of 38-46% IAC.
S, an aluminum alloy plate for a can body having a small variation in flange length, wherein the ear after necking has a 45 ° ear and an ear ratio of 0.05% or less. 2. 0.25 to 0.35 wt% of Si, Fe.
30 to 0.50 wt%, Cu 0.1 to 0.25 wt%, Mn
0.9 to 1.2 wt%, Mg 0.9 to 1.4 wt%, and Ti 0.005 to 0.05 wt% alone or B0.0
001 to 0.01 wt%, the balance being aluminum alloy ingot consisting of Al and inevitable impurities, homogenized annealing, hot rough rolling, hot finishing rolling, intermediate annealing,
Each step of cold rolling, finish annealing, said,
A method for manufacturing an aluminum alloy sheet, in which each step is an essential step, and each step is an optional step, wherein the homogenizing annealing is maintained at 580 to 615 ° C for 4 hours or more, and then from 550 ° C to 400 ° C. Up to 20 ° C
The hot rough rolling is started at the same temperature after homogenizing annealing or by reheating at a rate of 30 ° C./hour or more after cooling, and the end temperature is 400 to 480. C., hot finish rolling is started within 5 minutes after the completion of the hot rough rolling, a tandem type rolling mill having 3 or more stands is used, the total rolling ratio is 80% or more, and the finished sheet thickness is 1.8. ３3.0 mm, the end temperature is 310１０〜350 ° C., and the intermediate annealing is heated at a rate of 100 ° C./min or more using a continuous annealing furnace and is maintained at 400〜460 ° C. for 0１２０120 seconds. 2. The method according to claim 1, wherein the cooling is performed at a rate of not less than 70 [deg.] C. at a rate of not less than 70 [deg.] C./min, cold rolling is performed at a rolling reduction of 80 to 90%, and finish annealing is performed at 100 to 150 [deg.] C. Aluminum for can body with small variation in flange length Manufacturing method of the non-alloy plate.