JP2000234158A - Production of aluminum alloy sheet for can barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an Al alloy sheet low in an earing ratio and stably excellent in flanging formability, ironing properties and strength. SOLUTION: At the time of casting an Al-Mg-Mn alloy, thereafter subjecting it to homogenizing treatment and moreover executing hot rolling, the starting temp. is controlled to 350 to 580 deg.C, and, in the stage of 20 to 200 mm sheet thickness in the process of the hot rolling, in the region to a depth of 50 μm from the surface, recrystallization is allowed to occur by >=30%. Moreover, from the stage of >=20 mm sheet thickness in the process of the hot rolling to the completion of the hot rolling, the total hot rolling ratio is controlled to <=98%, the rolling temp. in each pass therebetween is controlled to 220 to 450 deg.C, the strain rate in each pass is controlled to 2 to 350/sec, the residence time between each pass is controlled to <=10 min, and the recrystallizing ratio in each pass is controlled to the range of 1 to 80%. Furthermore, the hot rolling finishing temp. is controlled to 200 to 330 deg.C, the finishing sheet thickness is controlled to 1.0 to 7.0 mm, and the average cooling rate of the hot rolled sheet directly after the completion of the hot rolling to a room temp. is controlled to <=100 deg.C/hr to obtain a hot rolled sheet having <=95% recrystallizing ratio at a room temp. and >=70 MPa proof stress. Moreover, after primary cold rolling of 2 to 60%, continuous annealing or batch annealing is executed, and then, final cold rolling of >=50% is executed.

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, flange formability (mouth openability) and ironing property (can-cutting property) during the production of DI cans are also important, and these ear ratios, flange formability, ironing property, and strength are required for can body materials. It can be referred to as main four elements, and it is strongly desired to improve these four elements in a well-balanced manner. Especially ear rate,
Of these four factors, it is difficult to control them. Therefore, in order to improve the balance of these four factors, appropriate control of the ear ratio is a very important issue.

Here, as a conventional general hot rolling method, a reversing mill and a reversing worm mill are used as a rough rolling mill and a finishing rolling mill, respectively, or a rolling mill for both rough rolling and finish rolling is used. In many cases, reversing mills are used for these hot rolling methods. However, in general, if the ear ratio is to be improved, there is a problem that the flange formability is lowered, and conversely, the flange formability is improved. If it is attempted to do so, it is difficult to reduce the ear ratio, for example, it is difficult to suppress the ear ratio to 3% or less at an aperture ratio of 1.9.

On the other hand, as a method for manufacturing a can body material for improving ear ratio, Japanese Patent Application Laid-Open No. Hei 5-317914 has already proposed a method of performing annealing twice during cold rolling. If annealing is performed twice during hot rolling, the rolling rate of final cold rolling cannot be increased,
In addition to the problem that insufficient strength is likely to occur,
This increases the production cost due to the repetition, and also causes a problem that the work hardening amount of the material at the time of can making becomes large and the flange formability deteriorates.

The present invention has been made in view of the above circumstances, and is a material capable of fully satisfying various demands for a can body, that is, strength, flange formability, ironing even when the thickness is reduced. It is a basic object of the present invention to provide a method for producing an aluminum alloy plate for a can body, which is excellent in easiness and has a low and stable ear ratio of a material in deep drawing.

[0010]

The inventors of the present invention have conducted various experiments and studies to solve the above-mentioned problems. As a result, recrystallization of the material in hot rolling, particularly, By strictly controlling the recrystallization state in the rolling pass, and performing the primary cold rolling on the obtained hot-rolled sheet and then performing the intermediate annealing, the inventors have found that the above-described problems can be solved. The present invention has been accomplished.

More specifically, the method for producing an aluminum alloy sheet for a can body according to the first aspect of the present invention is a method for producing an aluminum alloy sheet having a Mg content of 0.5 to 2.0%.
(% By weight, hereinafter the same), Mn 0.5-2.0%, Fe
0.1-0.7%, containing 0.05-0.5% of Si,
If necessary, after casting an aluminum alloy containing 0.005 to 0.20% Ti alone or in combination with 0.0001 to 0.05% B, with the balance being Al and unavoidable impurities , A homogenization treatment at a temperature in the range of 520 to 630 ° C. for 1 hour or more, and further hot rolling, (1) start hot rolling at a temperature in the range of 350 to 580 ° C .; 2) In the stage where the thickness during hot rolling is in the range of 20 to 200 mm, 5 mm from the surface
At least one recrystallization with a recrystallization rate of 30% or more is caused in a region up to a depth of 0 μm. (3) The total hot working from the stage where the thickness of the hot rolling is 20 mm or more to the end of hot rolling. The rolling reduction is 98% or less, and the rolling temperature in each rolling pass is in the range of 220 to 450 ° C., and the strain rate in each rolling pass is 2 to 350 / sec.
And the material residence time between each rolling pass is 1
Within 0 minutes, the recrystallization rate in each rolling pass (excluding the final pass) from the stage where the thickness of the hot rolling is 20 mm or more to the end of hot rolling (but excluding the final pass) is just before the start of the next pass.
(4) The hot rolling end temperature is in the range of 200 to 330 ° C., and the end plate thickness is 1.0 to 7.
(5) 20 immediately after the end of hot rolling.
The average cooling rate from a temperature in the range of 0 to 330 ° C. to room temperature is 100 ° C./hr or less, and (1) to (6) or more
According to (5), the recrystallization rate in a state of being cooled to room temperature after the completion of the hot rolling is controlled to 95% or less, and the proof stress is controlled to 70 MPa or more. Primary cold rolling is performed at a rolling rate within the range, and further 1 to 100
Heating to a temperature in the range of 330 to 620 ° C. at an average heating rate in the range of ° C./sec without holding or holding for 10 minutes or less, and an average cooling rate in the range of 1 to 100 ° C./sec. , Followed by further performing final cold rolling at a rolling rate of 50% or more.

The method of manufacturing an aluminum alloy plate for a can body according to the second aspect of the present invention is characterized in that
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 treatment-hot rolling-first cold rolling-continuous annealing-final cold rolling.

Further, in the method for manufacturing 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 material alloy, and the homogenization treatment-hot rolling-primary cooling is performed. The cold rolling is performed under the conditions defined in claim 1, and as the subsequent annealing, it is heated at an average heating rate of 0.1 ° C./sec or less and kept at a temperature in the range of 250 to 500 ° C. for 0.5 hour or more. Then, batch annealing for cooling at an average cooling rate of 0.1 ° C./second or less is performed, and then final cold rolling is performed at a rolling rate of 50% or more in the same manner as the method of claim 1.

According to a fourth aspect of the present invention, there is provided a method of manufacturing 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 reduction of 50% or more, the temperature is further reduced to 0.1 to 2 at a temperature in the range of 80 to 200 ° C.
A final annealing for 4 hours may be performed, and this is defined by the invention of claim 5.

[0016]

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, appearance defects such as abrasion and seizure called "goling" may occur. It is known that galling is affected by the size, amount, and type of a crystallized substance, and Mn is an essential element for forming the crystallized substance. 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 the 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 it is less than 10%, it is difficult to obtain an appropriate compound dispersion state. On the other hand, if the amount of Fe exceeds 0.7%, a primary crystal giant 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. 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 improving the 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 effective element for improving the strength, but if less than 0.05%, its effect is small, 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 in strength due to 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 balance of each of the above elements may be Al and inevitable impurities.

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. During the manufacturing process of can body material, hot rolling has an important influence on the control of ear ratio through the control of recrystallization behavior. Therefore, in the present invention, not only the hot rolling start temperature and the hot rolling end temperature, but also at least the sheet thickness of 20 m
The recrystallization behavior is strictly controlled by strictly defining the conditions of each rolling pass at the stage after m. Hereinafter, each condition in the hot rolling step will be described in more detail.

(1) The hot rolling start temperature is set to 350 to 58
Within the range of 0 ° C.

The starting temperature of hot rolling has a strong influence on the recovery and recrystallization behavior of the material during hot rolling, and in particular, the crystal orientation of the cube orientation (required for lowering the deep drawing edge of the final sheet). An aggregate of crystal grains having a cube orientation plays an important role in forming a cube band). If the hot rolling start temperature is lower than 350 ° C., the rolling texture tends to develop, but the edge cracking of the sheet tends to occur during the hot rolling. On the other hand, if the hot rolling is started at a high temperature exceeding 580 ° C., the cube Although the formation of the band is easy,
The surface quality of the plate is reduced. Therefore, the hot rolling start temperature must be in the range of 350 to 580 ° C.

(2) The thickness during hot rolling is 20 to 20
At a stage within the range of 0 mm, at least one recrystallization is performed at a recrystallization rate of 30% or more in a region (surface layer region) from the surface to a depth of 50 μm.

The sheet thickness during hot rolling is 20 to 200.
The recovery or recrystallization of the surface layer at a stage within the range of mm does not significantly affect the ear ratio of the final sheet, but has an effect on the improvement of surface quality and edge cracking. By causing the above-mentioned recrystallization at least once or more, it is effective in improving the surface quality of the final sheet and preventing edge cracking, and further contributes to the improvement of the flange formability and ironing property. Here, a region where recrystallization of 30% or more has occurred is only a shallow region of less than 50 μm from the surface, or a region at a depth of 50 μm from the surface has a recrystallization rate of 30%.
%, The above effects cannot be sufficiently obtained.

(3) From the stage where the thickness of the hot-rolled steel sheet is at least 20 mm or more to the end of hot-rolling, the recrystallization rate in the rolling pass (excluding the final pass) immediately before the start of the next pass is set to 1 Control within the range of 〜80%. Then, in order to secure a recrystallization rate of 1 to 80% in each rolling pass after the stage in which the plate thickness is 20 mm or more, from the stage in which the plate thickness in the middle of hot rolling is 20 mm or more to the end of hot rolling. The total hot rolling rate between the two is 98% or less,
And the rolling temperature in each rolling pass in the meantime is 220-
Within the range of 450 ° C., the strain rate in each rolling pass during that time is in the range of 2 to 350 / sec, and the material residence time between each rolling pass is 10 minutes or less.

The recrystallization rate during rolling in each rolling pass after at least the stage where the plate thickness is 20 mm or more has an important effect on the control of texture, and the recrystallization rate in each rolling pass during that time is 1 to 80%. Within the range, preferably 5 to 40
%, The cube orientation density of the material after the completion of hot rolling can be increased, and the 45 ° ear of the final plate can be lowered to achieve a low ear ratio. Note that the recrystallization rate in each rolling pass defined here is a volume fraction of recrystallization that occurs from the start of the rolling pass to immediately before the start of rolling in the next pass. Here, if the recrystallization rate exceeds 80% or is less than 1% even in one rolling pass among the rolling passes after the stage where the plate thickness is 20 mm, the density of the cube-oriented crystal grains after the completion of hot rolling is reduced. And the 45 ° ear of the final plate is raised. Further, the recrystallization rate in each rolling pass at a stage where the plate thickness is larger than 20 mm does not significantly affect the ear ratio of the final plate. However, even if the recrystallization rate of each rolling pass is controlled as described above from the stage where the sheet thickness is larger than 20 mm, no particular inconvenience is caused. Therefore, in the present invention, the sheet thickness during hot rolling is 20 mm or more. The recrystallization rate in each rolling pass after the step is defined.

As described above, in order to control the recrystallization rate in each rolling pass after the stage where the sheet thickness is 20 mm or more, within the range of 1 to 80%, preferably 5 to 40%, the rolling temperature and the It is necessary to appropriately control the strain rate of the rolling passes and the material residence time between the rolling passes. That is, when the plate thickness is 2
After the stage of 0 mm or more, first set the rolling temperature to 220 mm.
To 450 ° C., the strain rate of each rolling pass is in the range of 2 to 350 / s, and the residence time between each rolling pass (from the end of rolling in the preceding rolling pass to the start of rolling in the next rolling pass) ) Must be within 10 minutes. Here, if the rolling temperature after the stage where the plate thickness is 20 mm or more is lower than 220 ° C., it becomes difficult not only to secure the lower limit of the recrystallization rate described above, but also there is a possibility that edge cracking of the plate occurs during rolling. 450 ° C
If it exceeds, the recrystallization rate may exceed the upper limit. Further, if the strain rate in each rolling pass is less than 2 / sec, not only is it difficult to secure the lower limit of the recrystallization rate described above, but also the productivity is significantly reduced. If the speed exceeds 350 / sec, the surface quality may be degraded. Furthermore, if the residence time of the material between the rolling passes exceeds 10 minutes, recrystallization proceeds during the residence time, and the recrystallization rate in each rolling pass may exceed the upper limit. The properties are also significantly reduced.

(4) The hot rolling end temperature is 200 to 33
0 ° C and the thickness at the end of hot rolling is 1.0
It is within the range of 7.0 mm.

The end temperature (rising temperature) of the hot rolling is 20
If the temperature is lower than 0 ° C., not only the surface quality is deteriorated, but also the second
The recrystallization nucleation density around the phase particles increases, and the subsequent recrystallization increases the number of recrystallized grains other than the cube orientation, which is disadvantageous for low ear ratio control. On the other hand, hot rolling end temperature is 330 ° C
If it exceeds 300, it will be difficult to reduce the recrystallization rate to 95% or less and the yield strength to 70 MPa or more when cooled to room temperature after completion of hot rolling. If the sheet thickness (rising sheet thickness) at the end of hot rolling is less than 1.0 mm, it is difficult to control the sheet thickness accuracy in the hot rolling mill. On the other hand, if the sheet thickness after hot rolling exceeds 7.0 mm, In the final cold rolling after annealing, the rolling ratio becomes too high, and high strength is easily obtained, but the 45 ° ear becomes high and the ear ratio becomes large.

(5) 200 to 33 immediately after completion of hot rolling
The average cooling rate from a temperature in the range of 0 ° C. to room temperature is 10
0 ° C./hour or less.

[0040] Immediately after the end of hot rolling, 2
A cooling process from a temperature in the range of 00 to 330 ° C. to room temperature, particularly a cooling process to 100 ° C., is a process in which nucleation of cube-oriented recrystallized grains occurs, during which the cooling rate exceeds 100 ° C./hour. In such a case, nucleation of the recrystallized grains in the cube orientation becomes insufficient, which is disadvantageous for controlling the low ear ratio of the final sheet. The lower limit of the average cooling rate from a temperature in the range of 220 to 330 ° C. immediately after the end of hot rolling to room temperature is not particularly limited, but is preferably 1 ° C./hour or more. If the cooling rate during that time is less than 1 ° C./hour, recrystallization will occur almost completely, making it difficult to reduce the recrystallization rate in a state cooled to room temperature to 95% or less and the proof stress to 70 MPa or more. There is a risk.

(6) The recrystallization rate of the hot-rolled sheet (hot-rolled sheet) cooled to room temperature is 95% or less, and the proof stress is 70 MPa or more. This means that the hot-rolled sheet is not in the completely recrystallized state but in the partially recrystallized state.

The regulation of the recrystallization rate and proof stress value of the hot-rolled as-cooled sheet cooled to room temperature is an important point in the method of the present invention, and these values are used to control the low ear ratio of the final sheet and the appearance. Significantly affects defects. That is, when the self-annealing proceeds during cooling from the temperature in the range of 200 to 330 ° C. after hot rolling to room temperature and the recrystallization ratio exceeds 95% (that is, a completely recrystallized state or close to it) (Recrystallized state), or when the proof stress value falls below 70 MPa, the effect of expanding the recrystallized structure in the cube orientation cannot be obtained by the subsequent primary cold rolling and annealing. In addition, it is difficult to control the ratio at the same time, and at the same time, the crystal grains of the final sheet are coarsened, and the appearance defects such as rough skin and flow lines at the time of can making are liable to occur. Therefore, it is necessary to regulate the recrystallization ratio in a state cooled to room temperature to 95% or less and the proof stress value to 70 MPa or more. Also within this range, it is particularly preferable that the recrystallization ratio is 75% or less and the proof stress value is 90 MPa or more. The recrystallization rate in the state of being cooled to room temperature in this way mainly affects the hot rolling end temperature, the cooling rate from the hot rolling end temperature to room temperature, and furthermore, the composition of the alloy, By appropriately adjusting these in relation to each other, the recrystallization rate at room temperature can be controlled to 95% or less, and the proof stress when cooled to room temperature includes the above-mentioned recrystallization rate. As described above, the hot rolling end temperature, the cooling rate to room temperature, and the alloy composition should be controlled to 70 MPa or more by appropriately adjusting the alloy composition based on the mutual relationship. Can be.

With respect to the hot rolled sheet in a partially recrystallized state obtained by satisfying the above conditions (1) to (6), the primary cold reduction within the range of a rolling reduction of 2 to 60% is performed. Rolling is performed. By subjecting the hot-rolled sheet in the partially recrystallized state to primary cold-rolling to give a strain to the hot-rolled sheet, the subsequent annealing promotes the generation and growth of recrystallized grains in the cube orientation and the cube. The effect of suppressing the generation and growth of recrystallized grains other than the orientation can be obtained.

If the rolling reduction of the primary cold rolling on the hot rolled sheet is less than 2%, the effect of accelerating the formation and growth of recrystallized grains in the cube orientation due to insufficient strain and the recrystallized grains other than the cube orientation When the rolling reduction exceeds 60%, 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, the rolling reduction in the primary cold rolling of the hot rolled sheet was set in the range of 2 to 60%. Here, in the present invention, in particular, it is important that the rolling reduction of the primary cold rolling is allowed in a wide range of 2 to 60%, and the primary cold rolling reduction is optimized within such a wide range. By adjusting to
It has become possible to improve not only the low ear ratio of the final plate but also the balance of the four factors required for the above-mentioned can body. The reason why the wide range of the primary cold rolling reduction is allowed is that the hot rolling conditions are strictly regulated as described above, and the heat rolling is controlled so as to be advantageous for ear ratio control. This is because the recrystallization state in the cold rolling process was appropriately controlled.

As described above, the rolling ratio of the hot-rolled sheet is 2 to 6
After the first cold rolling of 0%, continuous annealing (CA
L) Alternatively, intermediate annealing is performed by batch annealing. This intermediate annealing is a necessary step for completely recrystallizing the material and reducing the ear ratio of the final sheet after final cold rolling.

When the continuous annealing is applied to the intermediate annealing after the primary cold rolling, the continuous annealing is performed at an average heating rate in the range of 1 to 100 ° C./sec to a temperature in the range of 330 to 620 ° C. After heating and holding for no more than 10 minutes,
The cooling is performed at an average cooling rate within a range of 100 ° C./sec. 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. If the ultimate temperature of heating is lower than 330 ° C., recrystallization hardly occurs. On the other hand, if the temperature exceeds 620 ° C., eutectic melting may occur. In addition, 1 to 330-620 ° C
Holding for more than 0 minutes impairs the productivity of continuous annealing.

On the other hand, when batch annealing is applied as the intermediate annealing after the primary cold rolling, the material is heated to a temperature in the range of 250 to 500 ° C. at an average heating rate of 0.1 ° C./sec or less. The temperature is maintained for 0.5 hours or more, and the average cooling rate is set at 0.
Cool at 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. On the other hand, if the heating and holding temperature is lower than 250 ° C., it is difficult to completely recrystallize.
At a high temperature exceeding 0 ° C., the recrystallization nuclei become coarse, and surface defects such as rough skin and flow lines tend to occur during can making. 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.

As described above, after intermediate annealing by continuous annealing or batch annealing, final cold rolling is performed at a rolling ratio of 50% or more in order to obtain a final sheet thickness and required strength. Here, the rolling rate of the final cold rolling is 50%.
If it is less than 10, the increase in strength 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 the final cold rolling may be subjected to DI forming as it is as the final sheet, but if necessary, the sheet after the final cold rolling may be subjected to a temperature of 80 to 200 ° C. A final anneal of 0.5 to 24 hours may be performed. 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 hours, the effect of improving the formability cannot be sufficiently obtained. If the annealing time exceeds 24 hours, the effect of improving the formability is saturated, and the productivity and the economy are reduced. It only impairs sex. Even if the final annealing is not actively performed, the same annealing effect as described above can be obtained by utilizing the processing heat generated by performing the final cold rolling at a high speed.

[0050]

EXAMPLES Ingots of alloy 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. Detailed conditions of the hot rolling are shown in Tables 2 to 4 in serial numbers 1 to 7. Further, the hot rolled sheet cooled to room temperature was subjected to primary cold rolling, followed by continuous annealing or batch annealing as intermediate annealing, and then to final cold rolling. After the final cold rolling, final annealing was performed except for the cases of production numbers 1, 3, and 5. The detailed conditions after the first cold rolling are shown in production numbers 1 to 7 in Table 5.

With respect to the aluminum alloy sheet 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 250 MPa or more is necessary as the proof stress after baking of the paint, and as for the ear ratio, if it exceeds 3%, it is known that troubles in the can-making are likely to occur. Have been.

Further, as the evaluation of the moldability of DI cans, the cutting ability (ironing property), the opening property (flange moldability), the seaming property, and the appearance defect were examined. Here, regarding the can-breaking property, the situation of occurrence of can breaking when 10,000 severe canning processes were performed continuously was examined, and for the mouth-opening property, the flange formability after 4-step necking was investigated, and further seaming was performed. The seamability after four-step necking was examined for the ductility, and the appearance defect of the flow line-like appearance defect along the rolling direction of the can body wall of the DI can and the occurrence of vertical streaks in the DI direction were examined for the appearance defect. Investigation and relative evaluation were carried out in five steps of 1 to 5 respectively. Table 6 shows the results. In Table 6, in the five-stage evaluation of the moldability of DI cans, the larger the number, the better, and a pass of "3" or higher was evaluated.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

[Table 4]

[0057]

[Table 5]

[0058]

[Table 6]

In Tables 1 to 6, Production Nos. 1 to 5 are alloys having a composition within the range specified by the present invention and satisfying the manufacturing process conditions specified by 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 250 MPa or more, and the sample had sufficient strength. It is clear that the moldability of the can, especially the ironing property and the flange moldability are also excellent.

On the other hand, in production number 6, the composition of the alloy is within the range specified by the present invention, but the manufacturing process conditions are out of the range specified by the present invention. That is, in the process of production number 6, the thickness of the plate is 25 m during hot rolling.
The recrystallization rate in the second pass from the stage m increases to 91%, which exceeds the range of 1 to 80% specified in the present invention, and the hot rolling finish temperature is 340 ° C, which is specified in the present invention. The recrystallization rate in the state of exceeding 200-330 ° C. and further cooling to room temperature after completion of hot rolling is 100%, and exceeds the upper limit of recrystallization rate of 95% of the present invention, and the proof stress value is 66 MPa. And the lower limit 70 defined in the present invention.
MPa, and in this case, the ear ratio of the final plate is 5.
It was as high as 7%, and was also inferior in can-cutting properties (ironing properties).

Production No. 7 is an example using an alloy F containing 0.45% of Mg, which is out of the range specified in the present invention. In this case, the strength after baking is low, and the ear ratio is high. The DI moldability was poor.

[0062]

As is clear from the above-mentioned embodiment, according to the method of the present invention, the four elements required as the material for the DI can body, namely, the ear ratio, the flange formability, the ironing property,
An aluminum alloy plate having an excellent balance of strength can be obtained reliably and stably. In particular, in the case of the method of the present invention, by controlling the hot rolling conditions finely, the primary cold rolling of the two cold rollings with the intermediate annealing interposed therebetween while securing a low ear ratio. The rate can be adjusted in a wide range, so that a low ear rate and high strength can be simultaneously and easily obtained.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference)

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 consisting of unavoidable impurities, it is subjected to a homogenization treatment at a temperature in the range of 520 to 630 ° C. for 1 hour or more, and further hot-rolled, (1) in a range of 350 to 580 ° C. Hot rolling is started at a temperature within the range, and (2) the thickness during hot rolling is 20 to 20
At a stage within a range of 0 mm, recrystallization with a recrystallization rate of 30% or more is caused at least once in a region from the surface to a depth of 50 μm. The total hot rolling reduction until the end of hot rolling is 98
% Or less, and the rolling temperature in each rolling pass in the meantime is in the range of 220 to 450 ° C., and the strain rate in each rolling pass is in the range of 2 to 350 / sec. With the residence time within 10 minutes,
The recrystallization rate in each rolling pass (excluding the final pass) from the stage where the thickness of the hot rolling is 20 mm or more to the end of hot rolling (excluding the final pass) is controlled within the range of 1 to 80% until immediately before the start of the next pass. And (4) the end temperature of the hot rolling is 200 to 330
(5) The average cooling rate from the temperature in the range of 200 to 330 ° C. immediately after the end of the hot rolling to the room temperature is set to 100 ° C. / h
r and (6) By the above (1) to (5), the recrystallization rate in a state of cooling to room temperature after completion of hot rolling is 9
5% or less, the proof stress is controlled to 70MPa or more. Then, the primary cold rolling is performed on the hot-rolled sheet at a rolling rate in the range of 2 to 60%, and further in the range of 1 to 100 ° C / sec. Continuous annealing in which heating is performed at a temperature within the range of 330 to 620 ° C. at an average rate of temperature rise within the range of no more than 10 minutes, and cooling is performed at an average cooling rate within the range of 1 to 100 ° C./sec. And then performing final cold rolling at a rolling rate of 50% or more, followed by a method for producing an aluminum alloy sheet for a can body. 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% B in combination with the balance being Al and unavoidable impurities,
In performing the homogenization treatment for 1 hour or more at a temperature in the range of 520 to 630 ° C. and further performing hot rolling, (1)
Hot rolling is started at a temperature in the range of 350 to 580 ° C., and (2) the recrystallization rate in a region from the surface to a depth of 50 μm from the surface at a stage in which the thickness of the hot rolling is in the range of 20 to 200 mm. 30% or more of recrystallization is caused at least once, and (3) the total hot rolling reduction from the stage where the thickness of the hot rolling is 20 mm or more to the end of hot rolling is 98% or less, and The rolling temperature in each rolling pass in
In the range of 20 to 450 ° C., the strain rate in each rolling pass is in the range of 2 to 350 / sec, and the material residence time between each rolling pass is 10 minutes or less, and Is controlled within a range of 1 to 80% until just before the start of the next pass in each rolling pass (excluding the final pass) from the stage of 20 mm or more to the end of hot rolling. The rolling end temperature is in the range of 200 to 330 ° C., the finished plate thickness is in the range of 1.0 to 7.0 mm,
(5) The average cooling rate from a temperature in the range of 200 to 330 ° C. immediately after the end of hot rolling to room temperature is set to 100 ° C./hr or less, and (6) hot rolling is performed by the above (1) to (5). 95% recrystallization rate after cooling to room temperature
Hereinafter, the proof stress is controlled to 70 MPa or more. Thereafter, the primary cold rolling is performed on the hot-rolled sheet at a rolling rate in the range of 2 to 60%, and further in the range of 1 to 100 ° C./sec. Continuous annealing is performed by heating to a temperature in the range of 330 to 620 ° C. at an average heating rate and holding without holding for 10 minutes or less, and cooling at an average cooling rate in the range of 1 to 100 ° C./sec. And finally performing a final cold rolling at a rolling rate of 50% or more. 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 inevitable impurities in the balance,
In performing the homogenization treatment at a temperature within the range of 30 ° C. for one hour or more and further performing the hot rolling, (1) 350
Starting hot rolling at a temperature within the range of ５580 ° C., (2)
At a stage where the thickness during hot rolling is within the range of 20 to 200 mm, the recrystallization rate is 3 in the region from the surface to a depth of 50 μm.
Causing at least one recrystallization of 0% or more; (3)
During the hot rolling, the total hot rolling rate from the stage where the thickness is 20 mm or more to the end of hot rolling is 98% or less, and the rolling temperature in each rolling pass during that time is 220 to 450.
° C range and the strain rate in each rolling pass is 2
３５０350 / sec, and the material residence time between each rolling pass is set to 10 minutes or less, and each rolling pass from the stage where the thickness of the hot rolling is 20 mm or more to the end of hot rolling (however, (Excluding the pass), the recrystallization rate until immediately before the start of the next pass is controlled within the range of 1 to 80%, (4) the end temperature of hot rolling is within the range of 200 to 330 ° C., and the end plate thickness is 1. (5) The average cooling rate from the temperature in the range of 200 to 330 ° C. immediately after the end of hot rolling to room temperature is 100 ° C./hr or less, and (6)
According to the above (1) to (5), the recrystallization rate in a state of cooling to room temperature after completion of hot rolling is 95% or less, and the proof stress is 7%.
0 MPa or more, and then perform primary cold rolling on the hot-rolled sheet at a rolling rate in the range of 2 to 60%, and further heat at an average heating rate of 0.1 ° C./sec or less. Then, it is kept at a temperature in the range of 250 to 500 ° C. for 0.5 hour or more, and subjected to batch annealing for cooling at an average cooling rate of 0.1 ° C./second or less, and then further finished at a rolling reduction of 50% or more. A method for producing an aluminum alloy plate for a can body, comprising performing cold rolling. 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% B in combination with the balance being Al and unavoidable impurities,
In performing the homogenization treatment for 1 hour or more at a temperature in the range of 520 to 630 ° C. and further performing hot rolling, (1)
Hot rolling is started at a temperature in the range of 350 to 580 ° C., and (2) the recrystallization rate in a region from the surface to a depth of 50 μm from the surface at a stage in which the thickness of the hot rolling is in the range of 20 to 200 mm. 30% or more of recrystallization is caused at least once, and (3) the total hot rolling reduction from the stage where the thickness of the hot rolling is 20 mm or more to the end of hot rolling is 98% or less, and The rolling temperature in each rolling pass in
In the range of 20 to 450 ° C., the strain rate in each rolling pass is in the range of 2 to 350 / sec, and the material residence time between each rolling pass is 10 minutes or less, and Is controlled within a range of 1 to 80% until immediately before the start of the next pass in each rolling pass (excluding the final pass) from the stage of 20 mm or more to the end of hot rolling. The rolling end temperature is in the range of 200 to 330 ° C., the finished plate thickness is in the range of 1.0 to 7.0 mm,
(5) The average cooling rate from a temperature in the range of 200 to 330 ° C. immediately after the end of hot rolling to room temperature is set to 100 ° C./hr or less, and (6) hot rolling is performed by the above (1) to (5). 95% recrystallization rate after cooling to room temperature
Hereinafter, the proof stress is controlled to 70 MPa or more. Thereafter, the primary cold rolling is performed on the hot-rolled sheet at a rolling rate in the range of 2 to 60%, and the average rise rate is 0.1 ° C./sec or less. Heating at a temperature rate, holding at a temperature in the range of 250 to 500 ° C. for 0.5 hour or more, performing batch annealing for cooling at an average cooling rate of 0.1 ° C./sec or less, and then further adding 50% or more A method for producing an aluminum alloy sheet for a can body, comprising performing final cold rolling at a rolling rate. 5. The method for manufacturing an aluminum alloy sheet for a can body according to claim 1, wherein the final cold rolling is performed, and then the temperature is further increased to 80 to 200 ° C.
A method for producing an aluminum alloy plate for a can body, comprising performing final annealing at a temperature within the range of 0.1 to 24 hours.