JPH11256291A - Manufacture of aluminum alloy sheet for can body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an Al alloy sheet excellent in strength and DI (drawing and ironing) formability which are required of a DI (drawn and ironed) can body material and having stably low earing rate at deep drawing. SOLUTION: An Al alloy, containing 0.5-2.0% Mg, 0.5-2.0% Mn, 0.1-0.7% Fe, and 0.05-0.5% Si, is cast, subjected to homogenizing treatment, and then hot-rolled. At this time, slab thickness at the beginning of roughing and initial roughing temperature are made to >=200 mm and 450 to 580'C, respectively, and also rolling rate from the beginning of roughing is regulated to >=25%, and the temperature until a stage of 150 to 15 mm plate thickness is reached is maintained at >=400 deg.C. In this stage, recrystallization of >=5% by volume ratio is allowed to occur at least one or more times over the whole plate. Moreover, the initial temperature of subsequent finish rolling is made to 250 to 400 deg.C, and the rolling speed of each pass at finish rolling and the rolling rate of each pass at finish rolling are made to (80 to 800) m/min and >=20%, respectively. Further, final temperature at finish rolling and final plate thickness are regulated to 200 to 320 deg.C and 1.0 to 7.0 mm, respectively. Subsequently, after batch annealing or continuous annealing after primary cold rolling is applied, final cold rolling at >=60% is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to DI processing (drawing).
Canning for 2-piece aluminum cans by ironing)
More specifically, the present invention relates to a method for producing an Al-Mg-Mn-based aluminum alloy plate used for a DI can body, particularly having a low deep drawing ear, a high strength after baking, and a formability during DI processing and a formability after baking. The present invention relates to a method for producing an aluminum alloy plate for a DI can body excellent in quality.

[0002]

2. Description of the Related Art In general, as a manufacturing process of a two-piece aluminum can, a can body material is subjected to DI forming by deep drawing and ironing to form a can body, and then trimmed to a predetermined size to be degreased.・ Washing process,
Further painting and printing and baking (baking)
And then necking the can body edge,
Usually, flanging is performed, and thereafter, a can is formed by performing seaming together with a separately formed can lid (can end).

[0003] As a raw material (can body material) of the DI can thus manufactured, a hard plate of JIS 3004 alloy, which is an Al-Mg-Mn alloy, has been widely used. This 3004 alloy is excellent in ironing workability, and shows relatively good formability even when cold-rolled at a high rolling ratio in order to increase strength, so that it is suitable as a DI can body. Have been.

[0004] As a method for producing such a 3004 alloy hard plate for a DI can body, after casting by a DC casting method or the like, the ingot is subjected to a homogenization treatment, and further subjected to hot rolling and cold rolling. Generally, a method is used in which a predetermined thickness is set and intermediate annealing is performed before or during cold rolling in the process.

[0005] By the way, it is strongly desired that the DI can body be made thinner mainly for the purpose of material cost reduction and weight reduction. In order to reduce the wall thickness, it is indispensable to increase the strength of the material in order to avoid the problem of a decrease in the buckling strength of the can caused by the reduction in the wall thickness.

Further, as for the material for the DI can body, not only the above-mentioned demand for high strength for the purpose of reducing the thickness, but also a low ear ratio at the time of DI molding is strongly desired. That is, a low ear ratio at the time of DI molding is required from the viewpoints of improving the yield at the time of DI molding and preventing the can body from being broken due to the cut end of the can body. Further, how to control the ear ratio affects the balance of strength, flange formability, and ear ratio, so that ear ratio control is a very important issue for can bodies.

[0007] However, in the above-mentioned conventional general method for manufacturing a can body, there is a limit in suppressing the ear ratio.
For example, it was difficult to suppress the ear ratio to 3% or less at an aperture ratio of 1.9.

Therefore, a method for producing a can body material for achieving a low ear ratio has already been proposed in, for example, JP-A-5-317914, JP-A-9-249932 and JP-A-9-268355.

[0009]

SUMMARY OF THE INVENTION The aforementioned Japanese Patent Laid-Open No. 5-31 is disclosed.
No. 7914 proposes a method in which annealing is performed twice in the middle of cold rolling. However, when annealing is performed twice in the middle of cold rolling, the rolling reduction in the final cold rolling cannot be increased. Therefore, there is a problem that the strength is apt to be insufficient, and there is a problem that a work hardening amount of the material at the time of can making is large and flange formability is deteriorated.

Japanese Patent Application Laid-Open No. 9-249932 proposes a method for achieving a low ear rate by strictly controlling the rolling speed, the area reduction rate, and the hot rolling end temperature in the final pass of hot rolling. Although this method is effective for achieving a low ear rate to some extent, the fluctuation of the ear rate due to manufacturing chances is still large, and it is insufficient for reliably and stably obtaining a low ear rate.

Furthermore, Japanese Patent Application Laid-Open No. 9-268355 proposes a method of achieving a low ear ratio by finely controlling the hot finish rolling conditions when a tandem rolling mill is used for hot finish rolling. However, the method of the present invention is limited to the case where a tandem mill is used for finish rolling, and no consideration is given to the case where a reversing mill is used. It is not effective for ear rate control when is applied.

As described above, it is difficult to sufficiently satisfy all the requirements for the can body by the conventionally proposed method, and in particular, even if a reversing mill is used, it is necessary to use the can body as the can body. It has been difficult to obtain a material that sufficiently satisfies various characteristics.

The present invention has been made in view of the above circumstances, and is a material capable of sufficiently satisfying various demands for a can body, that is, excellent in strength and flange formability even when the thickness is reduced. Further, it is a basic object of the present invention to provide a method capable of reliably and stably producing a low aluminum alloy sheet for a can body in a deep drawing.

The present invention also provides a method for producing an aluminum alloy sheet having excellent performance as a can body as described above, even when a reversing mill is used as a hot rolling facility, particularly a finishing mill. The purpose is to provide.

[0015]

As a result of various experiments and studies conducted by the present inventors to solve the above-mentioned problems, various conditions of the hot rolling process, especially recrystallization during hot rough rolling, were carried out. The present inventors have found that the aforementioned problems can be solved by appropriately controlling the conditions of the finish rolling after recrystallization and strictly controlling the conditions of the finish rolling, and have accomplished the present invention.

More specifically, the method for producing an aluminum alloy plate for a can body according to the first aspect of the present invention comprises the steps of:
Mn 0.5-2.0%, Fe 0.1-0.7%, Si
0.05-0.5%, and if necessary, 0.1-0.5%.
005 to 0.20% Ti alone or 0.000%
An aluminum alloy containing 1 to 0.05% of B in combination with the balance being Al and inevitable impurities is cast into a slab, and the slab is subjected to a temperature of 520 to 630 ° C for 1 hour or more. When the slab is subjected to the homogenization treatment and the slab is hot-rolled by hot rough rolling and subsequent hot finish rolling, (1) the slab thickness at the start of hot rough rolling is set to 200 mm or more; The rolling start temperature is in the range of 450 to 580 ° C., and (3) the temperature during the hot rough rolling, from the start of the rough rolling to the stage where the rolling ratio is 25% or more and the plate thickness is in the range of 150 to 15 mm. Is maintained at 400 ° C. or higher, and its 150 to 15 mm
At a thickness of the plate within the range of 5
% Or more recrystallization at least once, (4)
The start temperature of the hot finish rolling is set in the range of 250 to 400 ° C., (5) the rolling speed of each pass in the hot finish rolling is set in the range of 80 to 800 m / min, and (6) each of the hot finish rolling (7) The pass rolling rate is set to 20% or more.
Further, the rising temperature in hot finish rolling is set to 200 to 32.
Hot rolled sheet obtained under the above conditions (1) to (8), (8) and the ascending sheet thickness in hot finish rolling being in the range of 1.0 to 7.0 mm. To an average temperature of 0.1 ° C./sec.
After performing a batch annealing in which the temperature is maintained at a temperature in the range of about 500 ° C. for 0.5 hour or more, it is cooled at an average cooling rate of 0.1 ° C./sec or less, and then cold-rolled at a rolling rate of 60% or more. Is performed.

In the method for producing an aluminum alloy plate for a can body according to the second aspect of the present invention, the method comprises
g 0.5-2.0%, Mn 0.5-2.0%, Fe0.
1-0.7%, Si 0.05-0.5%, Cu 0.05-0.5%, Cr 0.05-0.3%, Z
n contains one or more of 0.05 to 0.5%, and if necessary, 0.005 to 0.20% of T
An aluminum alloy containing i alone or in combination with 0.0001 to 0.05% of B and the balance being Al and unavoidable impurities, and homogenized under the same conditions as the process conditions defined in claim 1. It is manufactured by a process of processing, hot rolling (rough rolling and finish rolling), batch annealing, and final cold rolling.

Further, in the method for producing an aluminum alloy sheet for a can body according to the third aspect of the present invention, the same aluminum alloy as the alloy defined in the first aspect is used as a raw material alloy, and the homogenization treatment-hot rolling (rough rolling and Finish rolling) under the conditions specified in claim 1, and then 2 to 25% of the hot-rolled sheet.
Primary cold rolling at a rolling rate of
330 to 62 at an average heating rate in the range of
2. A method according to claim 1, wherein after heating to a temperature in the range of 0 [deg.] C. and performing continuous annealing with no holding or holding for 10 minutes or less, cooling is performed at an average cooling rate in the range of 1 to 100 [deg.] C./sec. The final cold rolling is performed at a rolling rate of 60% or more in the same manner as in the above.

According to a fourth aspect of the present invention, there is provided a method for producing an aluminum alloy sheet for a can body, wherein an alloy having the same composition as the composition defined in the second aspect is used as the raw aluminum alloy. It is manufactured by.

In the above method, after the final cold rolling is performed at a rolling ratio of 60% or more, the temperature is further maintained at a temperature in the range of 80 to 200 ° C. for 0.5 hour or more. The final annealing may be performed, and this is defined by the invention of claim 5.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the reasons for limiting the composition of the aluminum alloy used in the method of the present invention will be described.

Mg: The addition of Mg is effective in improving the strength due to the solid solution of Mg itself, and can be expected to improve the strength by increasing the amount of work hardening accompanying the solid solution of Mg. An increase in strength due to aging precipitation of Mg ₂ Si due to coexistence can also be expected, and thus Mg is an indispensable element for obtaining the strength required for a can body. Mg is
Since it has the effect of increasing dislocations during processing, it is also effective for making recrystallized grains finer. However, when the Mg content is less than 0.5%, the above-mentioned effect is small. On the other hand, when the Mg content is more than 2.0%, although high strength is easily obtained, deformation resistance at the time of DI processing is increased and drawability and ironing property are reduced. Make it worse. Therefore, the Mg content is set in the range of 0.5 to 2.0%.

Mn: Mn is an effective element that contributes to improvement in strength and formability. In particular, in the can body material, which is the target application of the present invention, ironing is added during DI molding, and therefore Mn is particularly important. Emulsion type lubricants are usually used for ironing aluminum plates, but when the amount of Mn-based crystals is small, lubricating ability is insufficient with only emulsion type lubricants even if they have the same strength. However, there is a possibility that poor appearance such as abrasion and seizure called galling may occur. It is known that this phenomenon is affected by the size, amount, and type of the crystallized material, and Mn is an indispensable element for forming the crystallized material. If the Mn content is less than 0.5%, the solid lubricating effect of the Mn-based compound cannot be obtained, while if the Mn content exceeds 2.0%, a primary intermetallic giant compound of Al ₆ Mn is generated, resulting in remarkable molding. Impair the nature. Therefore, the amount of Mn is 0.1.
The range was 5 to 2.0%.

Fe: Fe is an element required to promote crystallization and precipitation of Mn and to control the amount of Mn solid solution in the aluminum matrix and the dispersion state of the Mn-based intermetallic compound. In order to obtain an appropriate compound dispersion state, it is necessary to add Fe according to the amount of Mn added. Fe content is 0.1%
If the amount is less than the above, it is difficult to obtain a proper compound dispersion state, while if the amount of Fe exceeds 0.7%, a primary crystal large intermetallic compound is easily generated with the addition of Mn, and the formability is significantly impaired. . Therefore, the range of the amount of Fe is 0.1 to 0.7.
%.

Si: The addition of Si contributes to the improvement of the strength of the can body material through age hardening due to precipitation of the Mg ₂ Si-based compound. Si is an element necessary for generating an Al-Mn-Fe-Si-based intermetallic compound and controlling the dispersion state of the Mn-based intermetallic compound. If the Si content is less than 0.05%, the above effects cannot be obtained, while if it exceeds 0.5%, the material becomes too hard due to age hardening, and the formability is impaired.
Therefore, the range of the amount of Si is set to 0.05 to 0.5%.

Ti, B: In ordinary aluminum alloys, a small amount of Ti or Ti and B is added to refine the ingot crystal grains. In the present invention, trace amounts are added if necessary. May be added alone or in combination with B. However, if the amount of Ti is 0.00
If it is less than 5%, the effect cannot be obtained, and if it exceeds 0.20%, a huge Al-Ti intermetallic compound is crystallized and the formability is impaired.
It was in the range of 5 to 0.20%. If B is added together with Ti, the effect of refining the ingot crystal grains is improved.
When B is added together with B, the effect is not obtained if the amount of B is less than 0.0001%, and if it exceeds 0.05%, coarse particles of Ti-B series are mixed and formability is impaired. When B is added, the amount of B is 0.0001 to 0.0.
It was within the range of 5%.

Cu, Cr, Zn: These are all elements that contribute to the improvement in strength, and one or more selected from these are added as necessary. Each of these elements will be further described.

Cu: Cu is dissolved in an aluminum matrix at the time of annealing, and Al-Cu-
It contributes to strength improvement utilizing precipitation hardening by precipitation as Mg-based precipitates. When the Cu content is less than 0.05%, the effect cannot be obtained. On the other hand, when Cu is added in excess of 0.5%, age hardening can be easily obtained, but it becomes too hard and impairs moldability. In addition, the corrosion resistance also deteriorates. Therefore, the range of the amount of Cu is set to 0.05 to 0.5%.

Cr: Cr is also an element effective for improving the strength, but less than 0.05% has little effect, and 0.3%
Exceeding the range is not preferred because the formation of giant crystals causes a reduction in moldability. Therefore, the range of the amount of Cr is 0.05 to
0.3%.

Zn: The addition of Zn contributes to the improvement of the strength due to the aging precipitation of Al-Mg-Zn-based particles.
If it is less than 0.5%, the effect cannot be obtained. If it exceeds 0.5%, there is no problem in the contribution to the strength, but the corrosion resistance is deteriorated. Therefore, the range of the amount of Zn is set to 0.05 to 0.5%.

The remainder of each of the above elements may be inevitable impurities with Al.

Next, the manufacturing process of the present invention will be described together with its operation.

First, an aluminum alloy ingot having the above-described alloy composition is cast by a DC casting method (semi-continuous casting method) or the like according to a conventional method. Next, the ingot is subjected to a homogenization treatment to homogenize segregation of the ingot and to reduce Mn.
Optimize the second phase particle size and distribution of the system. If the homogenization treatment temperature is less than 520 ° C, the effect of homogenization is insufficient,
On the other hand, if the temperature exceeds 630 ° C., eutectic melting may occur. If the homogenization treatment is performed for less than one hour, the homogenization will be insufficient. Therefore, the homogenization treatment is performed at a temperature in the range of 520 to 630 ° C.
It must be done for more than an hour. The upper limit of the homogenization treatment time is not particularly limited, but is usually preferably 48 hours or less in consideration of economy.

The slab subjected to the homogenization treatment is subjected to hot rolling. This hot rolling is classified into rough rolling and subsequent finishing rolling. In the case of the method of the present invention, a reversing mill (reversible rolling mill) is used for rough rolling, and a reversing mill or a reversing mill is used for finishing rolling. Although it is appropriate to use a single worm mill (reversible finishing mill), it is needless to say that the present invention is not limited thereto.

The conditions of this hot rolling step are extremely important in the case of the method of the present invention, and it is important to perform hot rolling in accordance with the conditions (1) to (8) for controlling ear ratio. . Therefore, the conditions (1) to (8) will be described in detail.

(1) The slab thickness at the start of hot rough rolling is 200 mm or more. The slab thickness at the time of the hot rough rolling is closely related to the condition of the item (3) described later, and
In order to secure the rolling reduction in the first half of hot rough rolling until reaching 0 mm and to sufficiently accumulate dislocations, it is necessary to set the slab thickness at the start of hot rough rolling to 200 mm or more, and preferably sufficient In order to obtain the amount of reduction, the thickness is set to 400 mm or more. The accumulation of dislocations in the first half of the hot rough rolling will be described in detail in the section (3).

(2) Starting temperature of hot rough rolling is 450 to 5
It is within the range of 80 ° C. The starting temperature of hot rough rolling has a strong influence on the recovery and recrystallization behavior of the material during hot rolling, and in particular, the crystallographic structure of the cube orientation (cube orientation) necessary for lowering the deep drawing edge of the final sheet. (Hereinafter, referred to as a cube band). When the hot rough rolling start temperature is lower than 450 ° C., the formation amount of the cube band tends to be insufficient.
If hot rough rolling is started at a high temperature exceeding the above range, formation of a cube band is facilitated, but the surface quality of the sheet is reduced. Therefore, the hot rough rolling start temperature is 450 to 580 ° C.
Must be within the range.

(3) During the hot rough rolling, the temperature from the start of the rough rolling to the stage where the rolling ratio is 25% or more and the thickness is in the range of 150 to 15 mm is maintained at 400 ° C. or more. In the step, recrystallization of 5% or more by volume relative to the entire plate is caused at least once. In the method of the present invention, during the hot rough rolling, the recrystallization in which the hot rough rolling reduction is 25% or more and the sheet thickness is in the range of 150 to 15 mm and the volume ratio is 5% or more with respect to the entire sheet. Is indispensable for the control of ear rate at least once. That is, the cube band formed by recrystallization at a stage where the hot rough rolling reduction is 25% or more and the plate thickness is in the range of 150 to 15 mm is stable, remains on the hot-rolled plate, and is finally cooled. This is effective for reducing the ear ratio of the final sheet after the cold rolling. In order to cause the recrystallization with the volume ratio of 5% or more, it is necessary to maintain the rolling temperature at 400 ° C. or more. If the rolling temperature is lower than 400 ° C., it becomes difficult to cause recrystallization at a volume ratio of 5% or more.
Therefore, in the present invention, during the hot rough rolling, the rolling temperature from the start of the hot rough rolling is 25% or more, and the rolling temperature up to the stage where the sheet thickness is in the range of 150 to 15 mm is 40.
The temperature was maintained at 0 ° C. or higher, and at that stage, recrystallization of 5% or more by volume relative to the entire plate was caused to occur at least once.

Here, at the stage where the hot rough rolling ratio from the start of the hot rough rolling is less than 25%, the distortion is small and the sheet thickness is 15%.
It is difficult to cause recrystallization at a volume ratio of 5% or more in the range of 0 to 15 mm. The fact that recrystallization is caused at a stage thicker than 150 mm has no particular adverse effect on the effect of the present invention. However, the recrystallization is caused at a stage thicker than 150 mm and the thickness of the subsequent plate is in the range of 150 to 15 mm. If the recrystallization with a volume ratio of 5% or more is not caused in the step, the effect of controlling the ear ratio cannot be sufficiently obtained. Therefore, the step of causing recrystallization with a volume ratio of 5% or more is as follows:
The rough rolling rate was 25% or more, and the plate thickness was in the range of 150 to 15 mm. At this stage, it is needless to say that recrystallization with a volume ratio of 5% or more may be performed twice or more. In addition, the recrystallization at this stage requires a volume ratio of 5% or more with respect to the whole plate as described above, but it is more preferable that the recrystallization is performed at a volume ratio of 15% or more. Further, in order to cause recrystallization at a volume ratio of 5% or more, preferably 15% or more at this stage, the rolling temperature is set to 400% until that stage as described above.
It is necessary to maintain the temperature at a temperature of 400 ° C. or higher. However, in order to surely cause recrystallization at a volume ratio of 5% or more, it is possible to maintain the temperature at 400 ° C. or higher and 1200 seconds or less during hot rough rolling as needed. .

Further, as described above, the rough rolling rate is 25%.
In order to reliably generate recrystallization having a volume ratio of 5% or more at a stage in which the plate thickness is in the range of 150 to 15 mm, not only the temperature up to the plate thickness stage is maintained at 400 ° C. or more, but also It is preferable that the rolling reduction per pass of each hot rough rolling pass from the slab thickness at the start of hot rough rolling to the sheet thickness of 150 mm is 15 mm or more, more preferably 40 mm or more. The rolling speed in rolling is preferably 40 m / min or more, more preferably 70 m / min or more.

That is, the slab thickness at the start of hot rough rolling (200 mm or more, preferably 400 mm
From above) to a plate thickness of 150 mm corresponds to almost the first half of the hot rough rolling. The rolling reduction per pass at this stage depends on the rolling temperature and rolling speed, and the material recovery and recrystallization. Affects behavior, especially grain size and sub-grain size. The rolling reduction per pass is 15mm
If it is less than 10, dislocations are unlikely to accumulate, crystal grains and sub-crystal grains tend to be coarse, and the number of cube bands is small, which adversely affects the ear ratio and mechanical properties of the material. Therefore, the rolling reduction per pass is preferably 15 mm or more, more preferably 40 mm or more. The upper limit of the amount of reduction in each pass does not need to be particularly limited. However, in order to maintain good surface quality, the amount of reduction per pass in each pass is usually set at 10%.
It is preferably set to 0 mm or less.

The rolling speed, together with the rolling temperature and the rolling reduction, has a strong influence on the recovery and recrystallization behavior of the material, in particular on the size of the crystal grains and sub-crystal grains. If the rolling speed of the hot rough rolling is less than 40 m / min, dislocations are unlikely to accumulate, the crystal grains and sub-crystal grains tend to be coarse, the number of cube bands is reduced, and the ear ratio and mechanical properties of the material are reduced. Has a bad effect on you. Also, if the rolling speed is low, the productivity also decreases. Therefore, the rolling speed is preferably at least 40 m / min, more preferably at least 70 m / min. Although there is no particular limitation on the upper limit of the rolling speed, it is usually preferably 1000 m / min or less in order to obtain good surface quality.

(4) The hot finish rolling start temperature is set to 250
The temperature is in the range of 400 ° C. Hot finish rolling is an important step in achieving proper dislocation density accumulation. That is, as described above, the sheet thickness is 150 to 1 in the hot rough rolling.
By introducing dislocations at an appropriate density in hot finish rolling around the cube band structure formed at a stage within a range of 5 mm, self-annealing by self-holding heat in a hot-rolled state, and further, In the subsequent annealing, it is possible to achieve the growth of the crystal structure in the cube orientation, which is advantageous for controlling the ear ratio of the final sheet after final cold rolling to be low. Here, the hot finish rolling start temperature is 250 ° C.
If it is less than 1, the surface quality is reduced and the number of recrystallized nuclei generated around the coarse particles is increased. In subsequent recrystallization, recrystallized grains other than the cube orientation are increased, which is disadvantageous for low ear ratio control. On the other hand, when the hot finish rolling start temperature is higher than 400 ° C., recovery and recrystallization are apt to proceed, and it becomes difficult to introduce sufficient dislocations. Therefore, the starting temperature of the hot finish rolling needs to be in the range of 250 to 400 ° C.
In addition, also in this range, especially in the range of 270-370 degreeC is preferable.

The hot finish rolling start temperature is 250-40.
In order to control the temperature within the range of 0 ° C., preferably 270 to 370 ° C., as described above, 150 to 1
Intermediate cooling (forced cooling) may be performed if necessary after securing recrystallization with a volume ratio of 5% or more at the stage of the plate thickness of 5 mm before the start of hot finish rolling. The intermediate cooling may be performed, for example, by forcibly cooling the plate with a coolant used in a hot rolling mill, or by forcibly cooling the plate with a cooling medium such as water, oil, or air. When the intermediate cooling is performed in this manner, the time required for securing the recrystallization at a volume ratio of 5% or more and performing the intermediate cooling at the stage of the plate thickness of 150 to 15 mm should be within 1800 seconds from the viewpoint of productivity. Is preferred.

(5) The rolling speed of each pass in the hot finish rolling is set within a range of 80 to 800 m / min. (6) Reduce the rolling ratio of each pass in hot finish rolling to 20%
Above. The strain rate of each pass of hot finish rolling has a significant effect on the formation of relocation nuclei and the formation of recrystallization nuclei with appropriate dislocation density, especially on the generation and growth of recrystallization nuclei with cube orientation. In order to promote the generation and growth of recrystallization nuclei having a cube orientation effective for achieving a low ear ratio, it is necessary to set the strain rate of each pass of finish rolling to 0.1 to 250.0 sec ⁻¹ , 1.0 to 90.0 sec optimally
It is preferable to control within the range of c ^-1 . The strain rate in each pass of the hot finish rolling is controlled by a combination of the rolling rate in each pass and the rolling ratio (reduction amount). Therefore, the strain rate of each pass of the hot finish rolling is set to 0.1 to 25 as described above.
0.0 sec ^-1 , preferably 1.0 to 90.0 sec ^-1
In order to control the rolling speed within the range, it is necessary to appropriately regulate the rolling speed and the rolling ratio of each pass.

If the rolling speed in each pass of the hot finish rolling is less than 80 m / min, the strain rate is low, and it is disadvantageous to introduce dislocations having an appropriate density, and it is difficult to generate and grow recrystallization nuclei in the cube orientation. It becomes difficult to control the low ear ratio, and if it exceeds 800 m / min, the surface quality is reduced.
The rolling speed of each pass of the hot finish rolling needs to be in the range of 80 to 800 m / min.

On the other hand, the rolling ratio of each pass of the hot finish rolling is 20%.
In the following, the strain rate becomes slow, it becomes difficult to introduce dislocations having an appropriate density, it becomes difficult to generate and grow recrystallization nuclei in the cube orientation, and it becomes difficult to control the low ear ratio. Therefore, the rolling ratio of each pass of the hot finish rolling was set to 20% or more. Although the upper limit of the rolling ratio of each pass of hot finish rolling is not particularly defined,
Usually, it is set to 85% or less from the viewpoint of surface quality.

(7) The ascending temperature in the hot finish rolling is in the range of 200 to 320 ° C. If the ascent temperature of the hot finish rolling is lower than 200 ° C., the surface quality is deteriorated, and the recrystallization nucleation around the second phase particles is increased. This is disadvantageous for low ear rate control. On the other hand, if the rising temperature exceeds 320 ° C., the fluctuation of the ear ratio of the final plate becomes large, and it becomes difficult to stably control the ear ratio of the final plate to a low ear ratio.

(8) The ascending thickness of the hot finish rolling is set to 1.0
It is within the range of 7.0 mm. If the finished thickness of the finish rolling is less than 1.0 mm, it is difficult to secure a sufficient rolling reduction in final cold rolling after annealing, and the strength of the final plate tends to be insufficient. On the other hand, if the upward thickness exceeds 7.0 mm, the rolling reduction tends to be too high in the final cold rolling after annealing, and the ear ratio tends to be high.

After the completion of the hot rolling under the conditions (1) to (8) as described above, the rolled sheet is subjected to intermediate annealing by batch annealing, or to a mild mode as described later. After the first cold rolling, intermediate annealing by continuous annealing is performed. This intermediate annealing is a necessary step for completely recrystallizing the material and reducing the ear ratio of the sheet after final cold rolling.

Here, when batch annealing is immediately applied to the hot-rolled sheet, the average annealing rate is 0.1 ° C./sec.
Heat to a temperature within the range of 0 to 500 ° C., hold at a temperature within the range for 0.5 hour or more, and cool at an average cooling rate of 0.1 ° C./sec or less. Here, if the average heating rate and the average cooling rate exceed 0.1 ° C./sec, there is a problem that the batch annealing method cannot uniformly heat or cool the entire hot rolled sheet coil. When the heating and holding temperature is lower than 250 ° C., it is difficult to completely recrystallize. On the other hand, when the temperature is higher than 500 ° C., recrystallization nuclei become coarse, and surface defects such as rough skin and flow lines are liable to occur during can manufacturing. Become. If the heating and holding time is less than 0.5 hour, it is difficult to completely recrystallize and it is difficult to uniformly heat the entire coil of the hot-rolled sheet. Although the upper limit of the heating holding time in the case of batch annealing is not particularly defined, it is usually within 24 hours from the viewpoint of economy.

Here, in the above description, intermediate annealing by batch annealing is performed on the hot-rolled sheet after hot rolling as it is, but continuous annealing can be applied to the intermediate annealing. However, continuous annealing with rapid heating and high-temperature short-time heating generally has a problem that formation of recrystallized grains in the cube orientation is smaller than in batch annealing with slow heating. However, from the viewpoint of increasing the strength by securing a sufficient amount of solid solution and refining the crystal grain structure,
It is more advantageous to apply a continuous annealing method of heating at a high temperature for a short time. Therefore, as a result of repeated investigations to develop a method that is advantageous for the generation of recrystallized grains with cube orientation while applying continuous annealing, we took advantage of the fact that the interaction between crystal grains with cube orientation and dislocations is small, By performing light primary cold rolling on the hot rolled sheet at a relatively small cold rolling reduction of 2 to 25% and then performing continuous annealing, the generation and growth of recrystallized grains in cube orientation are batch-annealed. It has been found that it can be promoted to the same extent as in the case of. Therefore, when continuous annealing is applied to intermediate annealing, the hot-rolled sheet is subjected to light primary cold rolling at a rolling reduction of 2 to 25%, and then to continuous annealing.

If the rolling reduction of the primary cold rolling on the hot-rolled sheet is less than 2%, the effect of accelerating the generation and growth of cube-oriented recrystallized grains due to insufficient strain, and the effect of recrystallized grains other than cube-oriented. When the rolling reduction exceeds 25%, the recrystallized grains in the cube orientation are also destroyed by a large amount of introduced strain. It becomes difficult to obtain a sufficient thickness, and the effect of reducing the ear ratio of the final plate cannot be obtained. Therefore, when the primary cold rolling is performed on the hot rolled sheet and then continuous annealing is performed, the rolling reduction in the primary cold rolling is 2 to 2
It was within the range of 5%.

As described above, the rolling reduction is 2 to 2 with respect to the hot-rolled sheet.
Continuous annealing after subjecting to 5% primary cold rolling is 1 to 10
Heating to a temperature in the range of 330 to 620 ° C. at an average temperature rise rate in the range of 0 ° C./sec, and without holding or after holding for 10 minutes or less, an average cooling rate in the range of 1 to 100 ° C./sec. And cooling conditions. Here, when the average heating rate and the average cooling rate are less than 1 ° C./sec, the productivity is significantly reduced in the continuous annealing (CAL) method, and the average heating rate and the average cooling rate exceeding 100 ° C./sec. Is disadvantageous for the formation of recrystallized grains having a cube orientation. In addition, the heating ultimate temperature is 330
If the temperature is lower than ℃, recrystallization is unlikely to occur.
Further, holding at 330 to 620 ° C. for more than 10 minutes impairs the productivity of continuous annealing.

As described above, after performing the intermediate annealing by batch annealing or continuous annealing, cold rolling is performed to obtain a final sheet thickness and obtain necessary strength. Here, when the final cold rolling reduction is less than 60%, the strength increase due to work hardening is small, and it is difficult to obtain the strength required for the final plate for can body.

The sheet after cold rolling may be subjected to DI forming as it is as a final sheet. However, if necessary, the cold-rolled sheet may be treated at a temperature in the range of 80 to 200 ° C. for 0.5 hour or more. May be subjected to final annealing. This final annealing is intended to improve the formability by recovering the ductility. However, if the temperature is lower than 80 ° C., the effect of improving the formability cannot be sufficiently obtained. If the annealing time is less than 0.5 hour, the effect of improving the formability cannot be sufficiently obtained. The upper limit of the annealing time is not particularly limited, but is preferably 10 hours or less from the viewpoint of productivity and economy.

[0057]

EXAMPLES Ingots of metal symbols A to F shown in Table 1 were cast into slabs by DC casting according to a conventional method.
Then, after performing a homogenization process, hot rolling was performed by hot rough rolling and hot finishing rolling. As the hot rolling equipment, a reversing mill was used for both the rough rolling mill and the finish rolling mill, and the hot rough rolling speed was 50 m / min or more in each case. Other detailed conditions of the hot rolling are shown in Tables 2 and 3 as serial numbers 1 to 7. For the rolled sheet after hot finish rolling,
Under the conditions shown in Table 4, batch annealing was performed, or continuous annealing was performed after primary cold rolling, and then final cold rolling was performed. After the final cold rolling, final annealing was performed except for the case of production number 5.

With respect to the aluminum alloy plate for a can body obtained as described above, the mechanical properties (tensile strength T
S, proof stress YS, elongation EL) and mechanical properties after heat treatment at 200 ° C. for 20 minutes assuming baking of paint (baking) were examined. The base plate was subjected to a cup deep drawing test under the conditions of a punch diameter of 48 mm, a blank diameter of 93 mm, and a clearance of 30%, and the ear ratio was examined. Here, as for the strength, a value of 270 MPa or more is required as the proof stress after baking of the paint (baking), and when the ear ratio exceeds 3%, it is known that troubles in the can-making are likely to occur. Have been.

Further, as evaluation of the moldability of DI cans, the can-easeability, mouth-opening property (flange moldability), seaming properties, and appearance defects were examined. Here, regarding the can-removability, the situation of occurrence of can breakage when 10,000 severe canning processes were performed continuously was examined.
The flange formability after the step necking was examined, the seaming property was examined after the four-step necking, and the appearance defect was measured using DI.
The appearance defects in the form of flow lines along the rolling direction of the can body wall of the can and the occurrence of vertical streaks in the DI direction were examined.
×× relatively evaluated. Table 5 shows the results.

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

[Table 3]

[0063]

[Table 4]

[0064]

[Table 5]

In Tables 1 to 5, Production Nos. 1 to 5 are all alloys having a component composition range specified in the present invention satisfying the manufacturing process conditions specified in the present invention. In each case, as shown in Table 5, the ear ratio was reliably lower than 3% to achieve a sufficiently low ear ratio, the proof strength after baking was 270 MPa or more, and the sample had sufficient strength. It is clear that the moldability is also excellent.

On the other hand, in production number 6, the composition of the alloy is within the range specified in the present invention, but the manufacturing process conditions are out of the range specified in the present invention. That is, in the case of the method of the present invention, the hot finish rolling start temperature is set to 400
In the case of manufacturing condition No. 6, the hot finish rolling start temperature is 447 ° C., which is higher than the upper limit of the temperature specified in the present invention. The rate was as high as 6.0%, and the can-opening property and the mouth-opening property were poor.

The production number 7 indicates that the alloy F has an Mg content of 0.48%, which is lower than the lower limit of the Mg content of the alloy specified in the present invention.
In this case, the strength after baking was low, the ear ratio was high, and the can-cutting property was poor.

[0068]

As is clear from the above-mentioned embodiment, according to the method of the present invention, the material for the DI can has a high strength enough to withstand the thinning of the can, and at the same time,
It is possible to reliably obtain an aluminum alloy plate which is excellent in DI formability, particularly flange formability, and has a stable and low deep drawing ear ratio.

Front page continued (51) Int.Cl. ⁶ identifications FI C22F 1/00 630 C22F 1/00 630A 630K 673 673 682 682 683 683 684 684C 685 685Z 691 691B 691A 691C 692 692A 694 694A 694B

Claims (5)

[Claims] 1. Mg 0.5-2.0% (weight%, the same applies hereinafter), Mn 0.5-2.0%, Fe 0.1-0.7%,
0.05 to 0.5% of Si, and if necessary, 0.005 to 0.20% of Ti alone or 0.0
001-0.05% B in combination with the balance being Al
After casting an aluminum alloy comprising unavoidable impurities into a slab, the slab is subjected to a homogenization treatment at a temperature in the range of 520 to 630 ° C. for 1 hour or more, and the slab is further subjected to hot rough rolling and subsequent hot rolling. In hot rolling by finish rolling, (1) the slab thickness at the start of hot rough rolling is 200 mm or more; (2) the hot rough rolling start temperature is in the range of 450 to 580 ° C; During the rough rough rolling, the temperature from the start of the rough rolling to the stage of the sheet thickness in the range of 25% or more and 150 to 15 mm is maintained at 400 ° C. or more.
In the stage of the thickness of the plate in the range of 0 to 15 mm, recrystallization of 5% or more by volume is caused at least once in the entire plate, and (4) the starting temperature of hot finish rolling is in the range of 250 to 400 ° C. (5) The rolling speed of each pass in hot finish rolling is 80
(6) The rolling reduction of each pass in hot finish rolling is 20%.
(7) Further, the rising temperature in hot finish rolling is set to 200
(8) And the ascending plate thickness in hot finish rolling is 1.0 to
The hot-rolled sheet obtained under the above conditions (1) to (8) was heated at an average temperature rising rate of 0.1 ° C./sec or less to obtain a temperature of 2 mm.
After performing batch annealing at a temperature in the range of 50 to 500 ° C. for 0.5 hour or more, it is cooled at an average cooling rate of 0.1 ° C./second or less, and then further cold-rolled at a rolling rate of 60% or more. A method for producing an aluminum alloy plate for a can body, which comprises rolling. 2. Mg 0.5-2.0%, Mn 0.5-
2.0%, Fe 0.1-0.7%, Si 0.05-0.
5%, Cu 0.05-0.5%, Cr0.
0.05-0.3%, Zn 0.05-0.5%, one or more of them, and further 0.00
5 to 0.20% Ti alone or 0.0001 to
After casting an aluminum alloy containing 0.05% of B in combination with the balance consisting of Al and inevitable impurities into a slab, the slab is homogenized for 1 hour or more at a temperature in the range of 520 to 630 ° C. After performing the treatment and hot rolling the slab by hot rough rolling and subsequent hot finish rolling, (1) the slab thickness at the start of hot rough rolling is 200 mm or more, and (2) the hot rough rolling is started. (3) During the hot rough rolling, the temperature from the start of the rough rolling to a stage in which the rolling ratio is 25% or more and the thickness is within a range of 150 to 15 mm is 400. ℃ ℃ 15
In the stage of the thickness of the plate in the range of 0 to 15 mm, recrystallization of 5% or more by volume is caused at least once in the entire plate, and (4) the starting temperature of hot finish rolling is in the range of 250 to 400 ° C. (5) The rolling speed of each pass in hot finish rolling is 80
(6) The rolling reduction of each pass in hot finish rolling is 20%.
(7) Further, the rising temperature in hot finish rolling is set to 200
(8) And the ascending plate thickness in hot finish rolling is 1.0 to
The hot-rolled sheet obtained under the above conditions (1) to (8) was heated at an average temperature rising rate of 0.1 ° C./sec or less to obtain a temperature of 2 mm.
After performing batch annealing at a temperature in the range of 50 to 500 ° C. for 0.5 hour or more, it is cooled at an average cooling rate of 0.1 ° C./second or less, and then further cold-rolled at a rolling rate of 60% or more. A method for producing an aluminum alloy plate for a can body, which comprises rolling. 3. Mg 0.5-2.0%, Mn 0.5-
2.0%, Fe 0.1-0.7%, Si 0.05-0.
5%, and if necessary, 0.005 to 0.2
0% Ti alone or 0.0001-0.05%
After casting an aluminum alloy containing Al and unavoidable impurities into a slab, the homogenizing treatment is performed on the slab at a temperature in a range of 520 to 630 ° C. for 1 hour or more, Further, in hot rolling the slab by hot rough rolling and subsequent hot finish rolling, (1) the slab thickness at the start of hot rough rolling is 200 mm or more, and (2) the hot rough rolling start temperature is 450 to (3) During hot rough rolling, the temperature from the start of rough rolling to a rolling ratio of 25% or more and a plate thickness in the range of 150 to 15 mm is maintained at 400 ° C. or more. And 15
In the stage of the thickness of the plate in the range of 0 to 15 mm, recrystallization of 5% or more by volume is caused at least once in the entire plate, and (4) the starting temperature of hot finish rolling is in the range of 250 to 400 ° C. (5) The rolling speed of each pass in hot finish rolling is 80
(6) The rolling reduction of each pass in hot finish rolling is 20%.
(7) Further, the rising temperature in hot finish rolling is set to 200
(8) And the ascending plate thickness in hot finish rolling is 1.0 to
The hot-rolled sheet obtained under the above conditions (1) to (8) is subjected to primary cold rolling at a rolling ratio of 2 to 25%, and further to 1 to 100 mm. 330 ° C./average heating rate in the range of
After performing continuous annealing in which heating is performed to a temperature in the range of 620 ° C. and no holding or holding for 10 minutes or less, 1 to 1
A method for producing an aluminum alloy sheet for a can body, comprising cooling at an average cooling rate in the range of 00 ° C./sec, and then performing final cold rolling at a rolling rate of 60% or more. 4. Mg 0.5-2.0%, Mn 0.5-
2.0%, Fe 0.1-0.7%, Si 0.05-0.
5%, Cu 0.05-0.5%, Cr0.
0.05-0.3%, Zn 0.05-0.5%, one or more of them, and further 0.00
5 to 0.20% Ti alone or 0.0001 to
After casting an aluminum alloy containing 0.05% of B in combination with the balance consisting of Al and inevitable impurities into a slab, the slab is homogenized for 1 hour or more at a temperature in the range of 520 to 630 ° C. After performing the treatment and hot rolling the slab by hot rough rolling and subsequent hot finish rolling, (1) the slab thickness at the start of hot rough rolling is 200 mm or more, and (2) the hot rough rolling is started. (3) During the hot rough rolling, the temperature from the start of the rough rolling to a stage in which the rolling ratio is 25% or more and the thickness is within a range of 150 to 15 mm is 400. ℃ ℃ 15
In the stage of the thickness of the plate in the range of 0 to 15 mm, recrystallization of 5% or more by volume is caused at least once in the entire plate, and (4) the starting temperature of hot finish rolling is in the range of 250 to 400 ° C. (5) The rolling speed of each pass in hot finish rolling is 80
(6) The rolling reduction of each pass in hot finish rolling is 20%.
(7) Further, the rising temperature in hot finish rolling is set to 200
(8) And the ascending plate thickness in hot finish rolling is 1.0 to
The hot-rolled sheet obtained under the above conditions (1) to (8) is subjected to primary cold rolling at a rolling ratio of 2 to 25%, and further to 1 to 100 mm. 330 ° C./average heating rate in the range of
After performing continuous annealing in which heating is performed to a temperature in the range of 620 ° C. and no holding or holding for 10 minutes or less, 1 to 1
A method for producing an aluminum alloy sheet for a can body, comprising cooling at an average cooling rate in the range of 00 ° C./sec, and then performing final cold rolling at a rolling rate of 60% or more. 5. The method for producing an aluminum alloy sheet for a can body according to claim 1, wherein the final cold rolling is performed at a rolling rate of 60% or more, and then 80 to 200. A method for producing an aluminum alloy sheet for a can body, which comprises performing final annealing at a temperature in the range of 0.5 ° C. for at least 0.5 hour.