JP2001214248A - Method for producing aluminum alloy hard sheet for can lid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard sheet low in an earing ratio. also small in the anisotropy of strength and moreover excellent in rivet formability and can openability as a can lid material for a stay-on tab type suction can. SOLUTION: At the time of subjecting an ingot of an Al alloy composed of 0.8 to 3.0% Mg, 0.01 to 1.2% Mn, 0.10 to 0.50% Fe, 0.05 to 0.40% Si and (Fe+Mn)/Si <=20 to hot rolling, as for the conditions of finish rolling, the pass number is controlled to 3 to 5, the ratio between the sheet thickness at the time of the start of the finish rolling and the sheet thickness upon the end of the same to 5 to 25, the draft in the final pass to 20 to 70%, and the rolling rate in the final pass to 200 m/min or more to obtain a hot rolled sheet having a recrystallizing ration of 85% or more, and in which the density in the cube orientation of the surface layer part of the sheet thickness is also 5 times or more than that in the random orientation, and moreover, final cold rolling is performed at a rolling ratio of 40 to 95%. Furthermore, the one, in addition to the above each component, containing a trace amount of Cu or/and Cr, and in which the content of Ti is controlled to 0.03% or less is used. Moreover, after the above process, final annealing of 100 to 240 deg.C×10 hr or more is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum can lid material, and more particularly, to a stainless steel can type lid for negative pressure cans containing no carbonic acid such as fruit juice, coffee and tea. As aluminum can lid material,
The present invention relates to a method for producing an aluminum can lid material having low strength anisotropy, low ear ratio, and excellent rivet formability and tearability (can openability).

[0002]

2. Description of the Related Art Generally, a stainless steel tub type aluminum can lid material has high strength and good formability, good tearability (can openability), and excellent rivet workability.
Further, it is required that the surface quality be excellent. Conventionally, 5000-type alloys (Al-Mg-based alloys, Al-Mg-Mn-based alloys) such as 5052 alloy and 5182 alloy have been widely used as this kind of aluminum can lid material. In particular, Al-Mg based 5052 alloy is often used as a can lid material for carbonated beverage cans such as fruit juice, coffee and tea, that is, a negative pressure can.

[0003]

In attaching the can lid to the can body, it is necessary to wind the can lid around the edge of the can body. However, when the deep drawing ear ratio of the can lid material is high,
In this winding process, there is a possibility that defective winding may occur. In addition, the can lid is generally subjected to score processing for opening the can, especially in the case of a stainless steel tub type can lid, since the processing rate of the score is large, when the maximum proof stress difference in each direction with respect to the rolling direction is large, that is, When the anisotropy of the strength is large, there is a risk that the impact at the time of dropping the can causes a crack from a low strength portion of the score portion to leak out the contents.

[0004] In addition, a rivet is usually formed on a can lid material in order to attach a tab (grab) to a drinking spout. That is, multi-stage overhang forming is performed on a portion where a tab is to be attached to form a projecting rivet portion, and a through hole provided in the tab is fitted to the rivet portion,
In addition, crush the tip of the rivet and push the tip,
Processing for fixing the tab to the rivet portion is usually performed, and such a series of processing is referred to as rivet forming. Therefore, the can lid material is required to have excellent rivet forming properties. If the rivet formability is poor, the material will crack at the time of rivet forming, that is, at the time of multi-stage overhang forming or at the time of rivet tip crushing,
This cracking not only causes the leakage of the contents of the can, but even if the crack does not completely penetrate the plate, the cracking causes peeling between the coating film and the plate, and as a result, the can Of the contents cannot be maintained in a good state for a long time. Therefore, it is also important for the can lid material that the rivet formability is excellent so that such cracks do not occur.

[0005] Further, the can lid of a beverage can is usually opened by tearing a drinking part, and a stay-on tab system which has been frequently used in recent years has a handle for a tab attached by rivet molding. By pulling up the part, the tip of the tab is lowered by the action of a lever with the attachment part (rivet part) of the tab as a fulcrum, thereby pushing down the drinking part and leaving the part of the drinking part torn from the score It is a method. In such a stay-tab type can lid, since the force of the fingers is indirectly used by the action of the lever, the way to apply the force so that the mouth part is smoothly torn from the score when the can is opened. It is difficult to finely adjust the amount, so that depending on how the force is applied, the drinking part may not be torn evenly from the score, and a failure to open the can may occur. In order to solve such a problem, a material having a small tear force (tear load) when opening the can, that is, a material having a good tear property is desired.

As described above, it is desired that an aluminum can lid material has low strength anisotropy, low ear ratio, good rivet formability, and good tearability. However, in the case of a 5000 series alloy conventionally used as a can lid material, in particular, a 5052 alloy can lid material used for negative pressure cans, a material which fully satisfies all of these characteristics has not been obtained. That is the fact.

The present invention has been made in view of the above circumstances, and has a stable and small anisotropy of strength, a reliable and stable low ear ratio, and excellent tearability and rivet formability. It is an object of the present invention to provide a can lid material that is optimal for a negative pressure can.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have repeatedly conducted intensive experiments and studies on an aluminum alloy hard plate for a can lid based on 5052 alloy. In particular, while appropriately adjusting the relative relationship between the contents of Fe, Mn, and Si, strictly regulating the conditions of finish rolling in hot rolling, and appropriately controlling the recrystallization texture of the hot-rolled up sheet. By doing
The inventors have found that the above-mentioned problem can be solved, and have accomplished the present invention.

More specifically, the method for producing an aluminum alloy hard plate for a can lid according to the first aspect of the present invention comprises the steps of:
%, Mn 0.01 to 1.2%, Fe 0.10 to 0.50
%, 0.05 to 0.40% of Si, and the value of {Fe content (%) + Mn content (%)} / Si content (%) is 20 or less, and the balance consists of Al and inevitable impurities. In performing hot rolling comprising rough rolling and finish rolling on the ingot of the alloy, the number of finish rolling passes after the completion of rough rolling is set within a range of 3 or more and 5 or less. The ratio t1 / t2 between the thickness t1 immediately before the start and the thickness t2 after the finish rolling is set in the range of 5 to 25, and the rolling reduction of the final pass in the finish rolling is 20.
The hot rolling is terminated at a rolling speed of 200 m / min or more in the final pass within a range of 70% to 70%, and the recrystallization rate is 85% or more and the orientation density of the cube orientation of the crystal grains in the surface layer portion of the sheet thickness is random. It is characterized in that an as-rolled hot-rolled plate having at least 5 times the orientation is obtained, and then the final cold rolling is performed at a rolling ratio of 40 to 95%.

[0010] The method for producing an aluminum alloy hard plate for a can lid according to the second aspect of the present invention is characterized in that:
0.01-1.2%, Fe 0.10-0.50%, Si
0.05 to 0.40%, and ΔFe amount (%) +
The value of Mn content (%) （/ Si content (%) is 20 or less;
Furthermore, Cu 0.01-0.50%, Cr 0.05-0.
An alloy containing one or two selected from 50%, the Ti content is regulated to 0.03% or less, and the balance is made of an alloy consisting of Al and unavoidable impurities. In performing hot rolling including rough rolling and finish rolling, the number of finish rolling passes after the completion of rough rolling is set to 3
The ratio t between the sheet thickness t1 immediately before the start of finish rolling and the sheet thickness t2 after the end of finish rolling is set within the range of not less than pass and not more than 5 passes
1 / t2 is set in the range of 5 to 25, the rolling reduction of the final pass in the finish rolling is set in the range of 20 to 70%, the rolling speed of the final pass is set to 200 m / min or more, and the hot rolling is terminated. A hot-rolled sheet having a crystallinity of 85% or more and an orientation density of crystal orientation of crystal grains in a surface layer portion of the sheet thickness of 5 times or more of a random orientation is obtained.
The final cold rolling is performed at a rolling reduction of 5%.

Further, the invention according to claim 3 is a method for manufacturing an aluminum alloy hard plate for a can lid according to any one of claims 1 and 2, further comprising:
The final annealing is performed at a temperature within the range of 00 to 240 ° C. for 10 hours or less.

[0012]

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

Mg: The addition of Mg is effective in improving strength due to solid solution itself, and has a large interaction with dislocations, so that strength can be expected to be improved by work hardening, and therefore the strength required as a can lid material Mg is an indispensable element to obtain the following. However, if the Mg content is less than 0.8%, sufficient strength as a can lid material cannot be obtained, while if it exceeds 3.0%, the production cost increases. Therefore, the amount of Mg is 0.8 ~
It was within the range of 3.0%.

Mn: The addition of Mn improves the tearability of the score portion and improves the openability of Al—Mn— (S
i) has a great effect on formation of Al-Fe-Mn- (Si) -based crystallization and improvement in strength. Mn amount is 0.01
%, The effect is small. On the other hand, if it exceeds 1.2%, the tearability is improved, but a large amount of crystallized matter is generated and the number of crystallized matter increases. It becomes difficult to sufficiently increase the density of the cube-oriented grains of the hot-rolled ascending sheet, which contributes to the generation of 0 ° / 90 ° ears and a low ear ratio, and also causes a reduction in rivet formability. Therefore, the Mn content is set in the range of 0.01 to 1.2%.

Fe: The addition of Fe improves the tearability of the score portion and improves the openability of Al—Fe—Mn.
-Has an effect on the generation of (Si) -based crystals. Also, Fe
Shows a great effect on the refinement of crystal grains for improving the formability required for a can lid material, and the more Fe is added, the more the crystal grains are refined. However, when the Fe content is less than 0.10%, the effect is not exhibited. On the other hand, when the Fe content exceeds 0.50%, although the tearing property is improved, a large crystallized substance is generated and the number of the crystallized substance increases. 0 during deep drawing of the plate
It is difficult to sufficiently increase the density of the cube-oriented grains of the hot-rolled ascending sheet which contributes to lowering of the ear ratio by generating the angle of 90 ° / 90 °, and also lowers the rivet formability.
Therefore, the amount of Fe was set in the range of 0.10 to 0.50%.

Si: Mg ₂ Si formed by Si
The crystallized substance also has the effect of improving the tearability of the score portion and improving the can openability. However, if the Si content is less than 0.05%, the effect is not exhibited, while if it exceeds 0.40%, although the tearing property is improved, a large crystallized substance is generated and the number of the crystallized substance increases, and In deep drawing, it is difficult to sufficiently increase the density of cube-oriented grains of the hot-rolled ascending sheet, which generates 0 ° / 90 ° ears and contributes to a low ear ratio, and also reduces the rivet formability. Invite you. Therefore, the amount of Si is set in the range of 0.05 to 0.40%.

{Fe content (%) + Mn content (%)} / Si content (%) ≦ 20: When the Fe content, the Mn content and the Si content satisfy these conditions, the Al—Fe—Mn—Si crystallized product is obtained. Can be promoted, and the size of the crystallized product can be reduced. As the crystallite size decreases, the density of the randomly oriented grains growing from the periphery of the crystallite decreases, so that 0 ° /
Cube orientation grains contributing to the generation of 90 ° ears are preferentially grown, and as a result, the ear rate of the product plate can be kept low. Therefore, in the present invention, Fe, Mn, Si
Not only as described above, but also the value of {Fe amount (%) + Mn amount (%)} / Si amount (%) was specified to be 20 or less.

Further, one or both of Cu and Cr may be added to the alloy used in the present invention in order to further improve the strength. The reasons for these limitations are as follows.

Cu: The addition of Cu is effective in improving the strength. Therefore, in order to further improve the strength of the can lid material, Cu may be added. However, if the Cu content is less than 0.01%, the above-mentioned effects cannot be obtained. On the other hand, if it is added in excess of 0.50%, the corrosion resistance which is an important property as a can lid material may be reduced. In addition, since the work hardening characteristics are increased, the moldability may be reduced. Therefore, the Cu addition amount when Cu is positively added is 0.01%.
-0.50%. Even if Cu is not positively added, less than 0.01% of C
Of course, u is allowed.

Cr: The addition of Cr is also effective for improving the strength. For further improving the strength, Cr may be added. However, if the Cr content is less than 0.05%, the effect is not exhibited, while if it exceeds 0.50%, giant crystallized substances are generated and the number of crystallized substances is excessively increased, leading to a reduction in formability. . Therefore, when Cr is positively added, the amount of Cr added is set in the range of 0.05 to 0.50%. Even when Cr is not positively added, 0.0 as inevitable impurities is used.
Of course, less than 5% Cr is acceptable.

Other than the above elements, Al and unavoidable impurities may be used. However, in a normal aluminum alloy, a small amount of Ti may be added to refine the ingot structure. Regarding the alloy used, a small amount of T
It is acceptable to add i. However, if the added amount of Ti is large, the ingot structure is unlikely to become feather-like crystals, and granular crystals are easily generated. And in the case of granular crystals, there is a risk that the crystallized substances that crystallize at the grain boundaries will be coarser than in the case of feathery crystals, and if the amount of Ti increases, a large crystallized substance is generated, Although the number of crystallized substances is increased and the tearing property is improved, a 0 ° / 90 ° lug is generated at the time of deep drawing of a product plate, and a hot rolled up plate which contributes to a low lug ratio is produced. It becomes difficult to sufficiently increase the density of the cube-oriented grains, and the rivet formability is reduced. Therefore, it is desirable that the Ti content be 0.03% or less.

Next, the manufacturing process in the method of the present invention will be described.

First, an aluminum alloy having the above-mentioned composition is melted according to a conventional method, and is cast according to a conventional method such as a DC casting method. The ingot is heated for hot rolling after performing the homogenization process, or is heated for hot rolling also serving as the homogenization process. The conditions for these heating are not particularly limited and may be in accordance with a conventional method. Of course, heating immediately before hot rolling is performed at a temperature not lower than the hot rolling start temperature and at which no melting occurs. .

The hot rolling is performed by rough rolling and finish rolling. In the case of the method of the present invention, the recrystallization texture of the hot-rolled ascending sheet is optimized to stably secure a low ear rate of the product sheet. At the same time, it is an important step for reducing the anisotropy of strength, and therefore it is necessary to strictly regulate the conditions of hot finish rolling.

That is, if the conditions of the hot finish rolling are appropriately regulated, recrystallization proceeds during the hot finish rolling and the subsequent cooling process, and the cube orientation (cubic orientation) as recrystallized grains or subcrystal grains. Crystal grains are generated, and the cube-oriented grains contribute to the generation of 0 ° / 90 ° ears on the product plate, and consequently control the generation of 45 ° ears to contribute to a low ear ratio and a difference in strength. Contributes to reduction of anisotropy. The recrystallization rate of the hot-finished rolled-up sheet is at least 85% by volume and the cube orientation density of the surface layer in the sheet thickness direction is at least 5 times the random orientation. It is necessary to stably achieve and obtain strength anisotropy. The cube azimuth density is 5 for random azimuth.
The term “double or more” means that the texture is measured by performing X-ray diffraction on the surface layer portion of the sheet thickness, and a three-dimensional azimuth distribution function is calculated. That is, it means that the powder sample having no orientation orientation is a random orientation, and the ratio of the X-ray diffraction intensity of the cube orientation to the X-ray diffraction intensity is 5 times or more.

If the recrystallization rate of the hot-finished rolled-up sheet is less than 85%, a considerable amount of the rolling texture contributing to the 45 ° ear remains, so that the azimuth density of the cube orientation contributing to the generation of 0 ° / 90 ° ears. Is difficult to sufficiently increase. Here, when the cube orientation density of the surface layer portion of the hot-rolled ascending sheet is less than 5 times the random orientation, the balance with the rolling texture formed in the subsequent cold rolling is lost, and the ear ratio of the product sheet is lost. Is high, and there is a possibility that poor tightening with the can body or the like may occur, and the anisotropy of the strength increases, making it difficult to secure stable openability and drop strength. Here, the sheet thickness portion means a region from the plate surface to a position at a depth of 200 μm.
Further, in order to achieve the recrystallization rate and cube orientation density of the hot-finished rolled sheet as described above, the following conditions (A) to (C) are necessary as the conditions of the hot finish rolling.

(A) Hot finish rolling is performed in 3 to 5 passes. If the number of passes of the hot finish rolling is less than 3, the rolling reduction per pass required to obtain the required hot-rolled ascending thickness becomes too large. In many cases, there is a possibility that the orientation density of the cube orientation grains in the surface layer portion of the sheet thickness after hot rolling has fallen below five times the random orientation. On the other hand, if the number of passes exceeds five, the equipment cost increases and productivity decreases. Therefore, the number of passes of the hot finish rolling was set to 3 to 5 passes.

(B) Sheet thickness t immediately before start of hot finish rolling
1 and the thickness t2 after completion of hot finish rolling t1 / t2
Is in the range of 5 to 25. If the ratio of t1 / t2 is less than 5, sufficient strain cannot be accumulated during hot finish rolling, and growth of cube-oriented grains cannot be promoted. On the other hand, when the ratio of t1 / t2 exceeds 25, the effect of shear deformation by the roll during hot finish rolling becomes too large, and after hot rolling, the orientation density of cube orientation grains in the surface layer portion of the sheet thickness becomes random orientation. May be less than 5 times. Therefore, 5 ≦ t1 / t2 ≦ 25 is defined.

(C) The reduction rate of the final pass in the hot finish rolling is within the range of 20 to 70%, and the rolling speed of the final pass is 200 m / min or more. If the rolling reduction of the final pass in hot finish rolling is less than 20%, it is difficult to accumulate sufficient strain, and it is difficult to promote the growth of cube-oriented grains that contribute to 0 ° / 90 ° ears. . On the other hand, when the rolling reduction of the final pass in the hot finish rolling exceeds 70%, the surface quality of the sheet is reduced, or the orientation density of the cube orientation grains in the surface layer portion of the sheet is less than 5 times the random orientation. There is a possibility that it will. If the rolling speed in the final pass of the hot finish rolling is less than 200 m / min, the accumulated strain due to the hot finish rolling becomes small and the temperature drop during the hot finish rolling becomes remarkable. It becomes difficult to increase the volume fraction of the cube-oriented grains of the plate. Therefore, the rolling reduction of the final pass in the hot finish rolling was set to 20 to 70%, and the rolling speed of the final pass was also specified to be 200 m / min or more. The upper limit of the rolling speed in the final pass of the hot finish rolling is not particularly limited.
Usually, it is 0 m / min or less.

The hot rough rolling is not particularly limited and may be carried out according to a conventional method. Generally, the hot rough rolling start temperature is about 400 to 580 ° C. and the rough rolling end temperature is 330 to 480. C., and the ratio t3 / t2 of the plate thickness t3 at the start of rough rolling to the plate thickness at the end of rough rolling (= the plate thickness immediately before the start of finish rolling) is preferably about 10 to 45.

In the hot finish rolling, the above (A) to
The conditions other than (C) are not particularly limited, but the finish rolling start temperature is preferably about 300 to 460 ° C, and the ascending temperature is preferably about 270 to 340 ° C.

A hot rolled sheet having a recrystallization ratio of 85% or more obtained by hot rolling as described above and an orientation density of the cube orientation at the surface portion of the sheet thickness of at least 5 times the random orientation is obtained. Is further subjected to final cold rolling to obtain a required thickness and strength.

The final cold rolling needs to be performed at a rolling rate of 40 to 95%. If the rolling reduction of the final cold rolling is less than 40%, the strength required as a can lid material cannot be obtained, while 95%
If the temperature exceeds the limit, the dislocation density introduced by the cold rolling becomes too large, the anisotropy of the strength increases, and the edge crack of the plate during the cold rolling tends to occur, and the material at the time of rivet forming is formed. Cracks are likely to occur, and it may be difficult to store the contents as a can in a good condition for a long period of time. Further, when the final cold rolling reduction is extremely increased to more than 95%, the development of the rolling texture becomes remarkable, the 45 ° ear in the product plate becomes high, and it is difficult to secure a low ear ratio. Will be. Therefore, the rolling reduction in the final cold rolling is set in the range of 40 to 95%. In order to ensure formability, it is desirable to perform rolling so that the temperature of the sheet at the time of final cold rolling is 100 ° C. or higher due to heat generation of the sheet during cold rolling. When final annealing (finish annealing) after cold rolling is not performed, it is effective to improve the formability by setting the temperature at which the sheet reaches 100 ° C. or more at the time of final cold rolling.

After the required thickness and strength are obtained by the final cold rolling as described above, this can be used as a can lid material as it is, but in some cases, as defined in claim 3, After the final cold rolling, final annealing (finish annealing) at a temperature in the range of 100 to 240 ° C. for 10 hours or less may be performed. Such final annealing has an effect of eliminating dislocations introduced by final cold rolling. Therefore, by performing the final annealing, it is possible to reduce the maximum proof stress difference generated in the final cold rolling and further improve the rivet formability. Here, if the final annealing temperature is lower than 100 ° C., the above-mentioned effects cannot be obtained. On the other hand, if the final annealing temperature is higher than 240 ° C., the progress of recovery is too large, resulting in insufficient strength. If the heating time of the final annealing exceeds 10 hours, the productivity will be reduced. Therefore, the annealing conditions for performing the final annealing after the final cold rolling were specified to be 10 hours or less at a temperature of 100 to 240 ° C. Although the lower limit of the heating time of the final annealing is not particularly defined, the above effect can be generally obtained in about 1 hour or more.

[0035]

EXAMPLE Alloy No. 1 in Table 1 was used. 1 to No. 9 were processed under various process conditions indicated by production codes A to R in Table 2 to obtain a final sheet thickness of 0.25 mm.
Finished. In general, since the can lid material is formed after baking coating, each plate manufactured under the conditions shown in Table 2 is coated and baked at 250 ° C. × 24 sec.
Ear ratio, mechanical properties, especially strength anisotropy, rivet formability and tearability were investigated. Table 3 shows the results. When the ear ratio exceeded 6%, the sample was rejected and marked with a cross, and the strength anisotropy was 0 °, 45 °, 9 ° with respect to the rolling direction.
Check the proof stress in each direction at 0 ° and determine the maximum difference (maximum proof stress difference)
Was determined, and when the value exceeded 25 MPa, the sample was rejected and marked with x. In addition, the cover material for negative pressure cans used as coffee cans and the like is generally not strictly required in terms of strength as compared to positive pressure cans used for beer, carbonated beverages, etc., but in the rolling direction. 0 °, 4
When both the proof stresses in the directions of 5 ° and 90 ° were less than 210 N / mm ² , the specimen was rejected and marked with a cross. Furthermore, regarding the evaluation of rivet formability, 200 rivet-formed can lids were produced, and the presence or absence of cracks was visually inspected. If at least one was found to be cracked, it was marked as unacceptable. . In addition, tearability was evaluated along the rolling direction using a plate that had been subjected to paint baking treatment, and the tearing load at that time was evaluated in comparison with the conventional material. did.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

In Tables 1 to 3, the serial numbers A, B,
G and J to M are all alloys (inventive alloys) within the component composition range specified in the present invention, and a process (inventive process) within the condition range specified in the present invention is applied as a manufacturing process. However, all of these examples of the present invention have a low ear ratio, low strength anisotropy, good rivet formability and tearability, and have been found to be excellently comprehensive as a can lid material. did.

On the other hand, the production codes C, D, E, F, H, and I all used the invention alloy, but the production process conditions deviated from the conditions of the process (invention process) defined in the present invention. In these cases, at least one or more properties were inferior. Specifically, the production code C is an example in which the recrystallization rate after the hot finish rolling is low and the cube orientation density of the surface layer portion of the sheet thickness is low, but in this case, the ear ratio is increased. . Production code D is an example in which the number of passes of the hot finish rolling is small, the ratio of the sheet thickness at the start and end of the hot finish rolling exceeds 25, and the cube orientation density of the surface layer portion of the sheet thickness is low. In this case, too, the ear rate was high. Production code E is an example in which the final cold rolling reduction is too high. In this case, not only the ear ratio is high, but also the maximum yield strength difference is large and the strength anisotropy is poor, and the rivet formability is also poor. I was Further, the production code F was in accordance with the process conditions of the present invention until the final cold rolling, but is an example in which the temperature of the final annealing after the final cold rolling was too high. In this case, the strength in each direction was low, Insufficient strength as lid material. Production code H is an example in which the reduction rate of the final pass of the hot finish rolling is low, the recrystallization rate after the hot finish rolling is low, and the cube orientation density of the surface layer portion of the sheet thickness is low. The rate has increased. The production code I is an example in which the rolling speed of the final pass of the hot finish rolling is too low, the recrystallization rate after the hot finish rolling is low, and the cube orientation density of the surface layer portion is too low. If you have a high ear rate.

The production codes N to R are examples in which the production process satisfies the conditions specified in the present invention, but the alloys which are out of the component composition range specified in the present invention (comparative alloys) are used. Also, in this case, one of the characteristics was inferior. Specifically, the production code N indicates the alloy No. having an excessive Mn content. In this case, the cube orientation density of the sheet thickness surface layer after hot finish rolling was low, the ear ratio of the product sheet was high, and the rivet formability was also inferior. The production code O has an excessive Mg content (Fe + M
n) / Si ratio of alloy no. In this case, the cube orientation density of the surface layer portion after the hot finish rolling was low, and the edge ratio of the product plate was high. The production code P indicates the alloy N having an excessive amount of Fe.
o. In this case, too, the cube orientation density of the surface layer portion after the hot finish rolling was low, the ear ratio of the product plate was high, and the rivet formability was poor. Further, the production code Q indicates that the alloy No. In this example, the cube orientation density of the surface layer portion after the hot finish rolling was low, the ear ratio was high, and the rivet formability was also poor. Further, the production code R indicates the alloy No. having an excessive amount of Si. This is an example using No. 9, but in this case, the tearing property was poor.

[0042]

According to the method for manufacturing an aluminum alloy hard plate for a can lid of the present invention, a can lid material having a low ear ratio, a small anisotropy in strength, and excellent rivet formability and tearability can be surely obtained. And can be obtained stably, therefore, if the plate obtained by the method of the present invention is used for a can lid,
When tightening with the can body, there is little risk of poor tightening, and there is little anisotropy in strength, so there is little risk of breaking from the score part due to the impact of dropping the can, and furthermore, at the time of rivet forming Excellent effect, such as a low risk of cracking and good openability.Especially suitable for the can lid of a stainless steel tub type can for negative pressure cans such as coffee and tea. Becomes

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Claims (3)

[Claims] 1. Mg 0.8 to 3.0% (mass%, the same applies hereinafter), Mn 0.01 to 1.2%, Fe 0.10 to 0.10
0.50%, Si 0.05 to 0.40%, and the value of {Fe amount (%) + Mn amount (%)} / Si amount (%) is 20 or less, and the balance is Al and inevitable In the case of using an alloy made of impurities as a raw material and performing hot rolling comprising rough rolling and finish rolling on the ingot, the number of finish rolling passes after the completion of rough rolling is set in a range of 3 or more and 5 or less. The ratio t1 / t2 between the thickness t1 immediately before the start of finish rolling and the thickness t2 after finish rolling is in the range of 5 to 25, and the rolling reduction of the final pass in finish rolling is in the range of 20 to 70%. , Set the final pass rolling speed to 200
m / min or more to end the hot rolling, and the recrystallization rate becomes 8
A hot-rolled ascending plate having an orientation density of 5% or more and a cube orientation of crystal grains at a surface layer portion of the sheet thickness being 5 times or more of a random orientation is obtained, and then subjected to final cold rolling at a rolling ratio of 40 to 95%. A method for producing an aluminum alloy hard plate for a can lid, which is performed. 2. Mg 0.8 to 3.0%, Mn 0.01 to 2.
1.2%, Fe 0.10-0.50%, Si 0.05-
0.40%, and the value of {Fe content (%) + Mn content (%)} / Si content (%) is 20 or less, and further 0.01 to 0.50% Cu and 0.05 to 0 Cr. .50%
Containing one or two selected from the group consisting of
When the amount of i is regulated to 0.03% or less and the balance is made of an alloy consisting of Al and unavoidable impurities, the ingot is subjected to hot rolling including rough rolling and finish rolling. The number of passes of the finish rolling is set within the range of 3 or more and 5 or less, and the ratio t1 / t between the thickness t1 immediately before the start of the finish rolling and the thickness t2 after the finish rolling is completed.
2 was set in the range of 5 to 25, the rolling reduction in the final pass in the finish rolling was set in the range of 20 to 70%, the rolling speed in the final pass was set to 200 m / min or more, and the hot rolling was terminated. Is 85% or more and the orientation density of the cube orientation of the crystal grains in the surface layer portion of the sheet thickness is 5 times or more of the random orientation, and then the final cold rolling is performed at a rolling reduction of 40 to 95%. A method for producing an aluminum alloy hard plate for a can lid. 3. The method for producing an aluminum alloy hard plate for a can lid according to claim 1, wherein the final cold rolling is further performed at a temperature within a range of 100 to 240 ° C. A method for producing an aluminum alloy hard plate for a can lid, wherein the final annealing is performed within a period of time.