JP2021095619A - Aluminum alloy sheet for cap material and method for producing the same - Google Patents

Abstract

To provide an aluminum alloy sheet for a cap material capable of improving workability while suppressing environmental load by using scrap materials as a primary raw material and to provide a method for producing the same.SOLUTION: There is provided an aluminum alloy sheet for a cap material which contains 0.9 mass% or more and 1.6 mass% or less of Si, 0.2 mass% or more and 0.6 mass% or less of Fe, 0.15 mass% or more and 0.4 mass% or less of Cu, 0.6 mass% or more and 1.1 mass% or less of Mn, 0.04 mass% or more and 0.2 mass% or less of Mg, 0.2 mass% or more and 0.6 mass% or less of Zn, less than 0.05 mass% of Cr, less than 0.1 mass% of Ti and less than 0.06 mass% of Zr and the balance being Al and unavoidable impurities, wherein the aluminum alloy sheet has a sheet thickness of 0.20 mm or more and 0.26 mm or less, a tensile strength of 150 MPa or more and 250 MPa or less, a yield strength of 140 MPa or more and 240 MPa or less and an ear rate of 6% or less.SELECTED DRAWING: None

Description

The present invention relates to an aluminum alloy plate for a cap material which is a cap of a bottle can made of an aluminum bottle or the like, and a method for manufacturing the same.

Aluminum or an aluminum alloy is a highly recyclable material. It is known that when an aluminum alloy is manufactured by reusing this scrap material of aluminum or an aluminum alloy, the _{amount of CO 2} generated can be significantly suppressed and the environmental load can be reduced as compared with the case where an aluminum bullion is used. There is. As an aluminum alloy plate made by reusing such scrap material, for example, the aluminum alloy plates described in Patent Documents 1 and 2 are known.

For example, the aluminum alloy plate of Patent Document 1 contains Si: 0.5 to 1.5%, Mg: 0.2 to 2.0%, Fe: 1.5% or less, Mn: 1 in mass%. .0% or less, Cr: 0.5% or less, Zr: 0.5% or less, V: 0.3% or less, Ti: 0.2% or less, Zn: 1.5% or less, Cu: 1.0 % Or less, and the total content of Bi, Sn, Ga, Co, Ni, Ca, Mo, Be, Pb, W is 0.015% or more and 0.5% or less, and the balance is Al and impurities. Consists of.

The aluminum alloy plate described in Patent Document 1 has an average cooling rate of 40 ° C./h from 500 ° C. to 350 ° C. after homogenizing heat treatment of an aluminum alloy ingot having the above composition at a temperature of 500 ° C. or higher and lower than the melting point. The temperature is set to less than 100 ° C./h, and after cooling to a temperature of 200 ° C. or lower, hot rolling is started after reheating to a temperature of 300 to 450 ° C., and the end temperature of this hot rolling is 170 to 300 ° C. A hot-rolled plate is manufactured, and the hot-rolled plate is cold-rolled without prior annealing to produce a cold-rolled plate, and the cold-rolled plate is solution-treated at a temperature of 560 ° C. or higher. Manufactured by quenching. As a result, in the aluminum alloy plate described in Patent Document 1, the average number density of all dispersed particles having a size of 0.5 μm or more is 3,000 to 20,000 particles / mm ² , and the measured size of the dispersed particles is X μm. In the coordinates with the axis and the number density of Y pieces / mm ² as the vertical axis, the dispersed particles having a size of X of 10 μm or less are 1000 in A / B in the dispersed particle size distribution formula represented by Y = Aexp (BX). The range is from 40,000, and B is in the range of 0.5 to 2.

Further, the aluminum alloy plate described in Patent Document 2 has Si: 0.5 to 1.4% by mass, Fe: 0.3 to 1.1% by mass, Cu: 0.1 to 0.3% by mass, Mg. : 0.03 to 0.6% by mass, Mn: 0.7 to 1.4% by mass, Ti: 0.01 to 0.1% by mass, and the balance: Al and impurities, and Zn as an impurity is 1. It has a component composition of less than 0.0% by mass, Cr as an impurity is less than 0.1% by mass, and Ni as an impurity is 0.1% by mass or less.

The aluminum alloy plate described in Patent Document 2 is obtained by continuously casting an aluminum alloy molten metal having the above composition into a slab having a thickness of 3 to 10 mm using a thin slab continuous casting machine, homogenizing the slab, and hot rolling. After winding directly on the coil, cold rolling is performed, the coil is inserted into a batch furnace, intermediate annealing is performed at a holding temperature of 430 to 510 ° C. for 0.5 to 12 hours, and then final. It is manufactured by cold rolling with a cold rolling ratio of 50 to 90% and final annealing. As a result, the aluminum alloy plate described in Patent Document 2 has a tensile strength of more than 180 MPa, a 0.2% proof stress of less than 140 MPa, an elongation value of 23% or more, and an average particle size of recrystallized grains of less than 30 μm. It becomes a certain cold-spread annealing material.

JP-A-2007-169740 JP-A-2015-96650

By the way, the aluminum alloys described in Patent Documents 1 and 2 are formed for an automobile body, and it is difficult to use them as they are as an aluminum alloy for a cap material. Therefore, an aluminum alloy plate for a cap material suitable for processing containing scrap material as a main component is desired.

The present invention has been made in view of the above circumstances, and provides an aluminum alloy plate for a cap material and a method for manufacturing the same, which can improve workability while suppressing an environmental load by using scrap material as a main raw material. The purpose.

As a result of diligent research, the researchers analyzed the components of the scrap material generated in the aluminum rolling mill, examined in detail the effects of the alloying elements contained in the scrap material in detail, selected the alloy component range, and then selected the alloy component range. By appropriately controlling the combination of manufacturing conditions, we have found an aluminum alloy material for cap materials that can be used for caps of bottle cans.

That is, the aluminum alloy plate for a cap material of the present invention has Si: 0.9% by mass or more and 1.6% by mass or less, Fe: 0.2% by mass or more and 0.6% by mass or less, and Cu: 0.15% by mass. 0.5% by mass or less, Mn: 0.6% by mass or more and 1.1% by mass or less, Mg: 0.04% by mass or more and 0.2% by mass or less, Zn: 0.2% by mass or more and 0.6% by mass % Or less, Cr: less than 0.05% by mass, Ti: less than 0.1% by mass, Zr: less than 0.06% by mass, the balance is composed of Al and unavoidable impurities, and the plate thickness is 0.20 mm or more and 0. The tensile strength is 150 MPa or more and 250 MPa or less, the withstand force is 140 MPa or more and 240 MPa or less, and the ear ratio is 6% or less.

In the present invention, the plate thickness is set to 0.20 mm or more and 0.26 mm or less. If the plate thickness is less than 0.20 mm, sufficient pressure resistance as a cap material cannot be maintained, and if it exceeds 0.26 mm, winding cannot be performed with an appropriate load. Further, the tensile strength is set to 150 MPa or more and 250 MPa or less. If the tensile strength is less than 150 MPa, the pressure resistance of the cap material is insufficient, and if it exceeds 250 MPa, the workability is lowered and molding defects may occur. Further, the proof stress is set to 140 MPa or more and 240 MPa or less. Similar to the tensile strength, if the proof stress is less than 140 MPa, the withstand voltage strength is insufficient, and if it exceeds 240 MPa, the workability is lowered and molding defects may occur. Further, since the ear ratio is less than 6%, it is possible to suppress trim chipping of the cap material and distortion during printing on the cap material, and it is possible to improve workability.
The "ear ratio" is a value derived from the average value of the height of the peak and the average value of the height of the valley formed on the side surface (tip) of the cylindrical portion of the cap material by the following formula. ..
(Equation) Ear ratio (%) = (Average value of mountain height-Average value of valley height) / Average value of valley height x 100

Si contributes to the improvement of the tensile strength of the aluminum alloy plate for the cap material. If it is less than 0.9% by mass, the tensile strength decreases, and if it exceeds 1.6% by mass, the tensile strength becomes too high and between the metals. The proportion of compound increases.
Fe contributes to the improvement of the tensile strength of the aluminum alloy plate for the cap material. If it is less than 0.2% by mass, the tensile strength decreases, and if it exceeds 0.6% by mass, the proportion of the intermetallic compound increases.
Cu contributes to the improvement of the tensile strength of the aluminum alloy plate for the cap material, and if it is less than 0.15% by mass, the tensile strength decreases, and if it exceeds 0.5% by mass, the tensile strength becomes too high.
Mn contributes to the improvement of the tensile strength of the aluminum alloy plate for the cap material. If it is less than 0.6% by mass, the tensile strength decreases, and if it exceeds 1.1% by mass, the tensile strength becomes too high and between the metals. The proportion of compound increases.
Mg contributes to the improvement of the tensile strength of the aluminum alloy plate for the cap material. If it is less than 0.04% by mass, the tensile strength decreases, and if it exceeds 0.2% by mass, the tensile strength becomes too high.
Zn contributes to the improvement of the tensile strength of the aluminum alloy plate for the cap material, and if it is less than 0.2% by mass, molding defects may occur during the processing (molding) of the cap material, and 0.6% by mass. If it exceeds, the tensile strength becomes too high.

Cr does not necessarily have to be contained, and if it is contained in an amount of 0.05% by mass or more, the tensile strength of the aluminum alloy plate for the cap material becomes too high.
Ti does not necessarily have to be contained, and if it is contained in an amount of 0.1% by mass or more, the surface of the aluminum alloy plate for the cap material becomes rough.
Zr does not necessarily have to be contained, and if it is contained in an amount of 0.06% by mass or more, the tensile strength of the aluminum alloy plate for the cap material becomes too high.

The method for producing an aluminum alloy plate for a cap material of the present invention contains 60% by mass or more of aluminum scrap material, Si: 0.9% by mass or more and 1.6% by mass or less, Fe: 0.2% by mass or more and 0. 6% by mass or less, Cu: 0.15% by mass or more and 0.5% by mass or less, Mn: 0.6% by mass or more and 1.1% by mass or less, Mg: 0.04% by mass or more and 0.2% by mass or less, Zn: 0.2% by mass or more and 0.6% by mass or less, Cr: less than 0.05% by mass, Ti: less than 0.1% by mass, Zr: less than 0.06% by mass, and the balance is Al and unavoidable. An aluminum alloy composed of impurities is melt-cast and then homogenized and hot-rolled to form a first sheet metal with a thickness of 2.0 mm or more and 3.6 mm or less, which is completely softened and annealed. After the first cold rolling, after the first cold rolling, intermediate annealing is performed in which the temperature is maintained at 400 ° C. or higher and 550 ° C. or lower for 5 seconds or longer and 30 seconds or shorter, and then the final cold rolling ratio is 30% or more and 70. A second plate material having a thickness of 0.20 mm or more and 0.26 mm or less is formed by cold rolling at% or less, and the second plate material is subjected to final annealing at 180 ° C. or more and 260 ° C. or less for 3 hours or more and 5 hours or less.

In the present invention, the thickness of the first plate material is set to 2.0 mm or more and 3.6 mm or less by hot rolling, and the final thickness is set to 0.20 mm or more and 0.26 mm or less. The tensile strength of the plate can be 150 MPa or more and 250 MPa or less, the proof stress can be 140 MPa or more and 240 MPa, and the ear ratio can be 6% or less.
If the thickness of the first plate material is less than 2.0 mm, it cannot be rolled with a uniform thickness, and if it exceeds 3.6 mm, the productivity decreases. Further, if the second plate material (final thickness of the aluminum alloy plate for cap material) is less than 0.20 mm, sufficient pressure resistance as a cap material cannot be maintained, and if it exceeds 0.26 mm, it is wound with an appropriate load. Can't be done.

If the temperature of the intermediate annealing is less than 400 ° C or the holding time is less than 5 seconds, the tensile strength is insufficient, and the temperature of the intermediate annealing exceeds 550 ° C or the holding time exceeds 30 seconds. The productivity of the aluminum alloy plate for the cap material is reduced.
If the final cold spreading ratio is less than 30%, the tensile strength decreases, and if it exceeds 70%, the tensile strength becomes too high and the ear ratio may exceed 6%.
If the final annealing temperature is less than 180 ° C., the workability is lowered, and if it exceeds 260 ° C., the tensile strength is lowered. Further, if the holding time of the final annealing at the above temperature is less than 3 hours, the workability is lowered, and if it exceeds 5 hours, the productivity of the aluminum alloy plate for the cap material is lowered.

Further, the first plate material formed by the homogenization treatment and the hot rolling is subjected to the second cold rolling with a reduction ratio of 10% or more and 40% or less, and then the complete softening annealing is performed. May be applied.
When recrystallization progresses too much in the hot rolling step, the strain introduced in the mild cold rolling (second cold rolling) serves as a driving force to promote recrystallization.
If the reduction rate is less than 10%, the driving force may be insufficient, and if it exceeds 40%, the rolled texture is excessively developed, and even after recrystallization, the structure in a random orientation is formed. It may not be obtained and the ear rate may increase.

According to the present invention, it is possible to provide an aluminum alloy plate for a cap material which can improve workability while suppressing an environmental load by using a scrap material which is difficult to reuse as a main raw material.

Hereinafter, embodiments of the aluminum alloy plate for a cap material according to the present invention will be described.

[Composition of aluminum alloy plate for cap material]
The aluminum alloy plate for the cap material becomes a cap material to be attached to a bottle can such as an aluminum bottle by being subjected to drawing processing or the like. The aluminum alloy plate for the cap material is formed of an aluminum alloy whose main raw material is scrap material. Specifically, the aluminum alloy to be the aluminum alloy plate for the cap material contains 60% by mass or more of the scrap material, and may be entirely formed of the scrap material.
Further, such scrap material is generated in an aluminum rolling mill. For example, a core material made of an Al—Mn—Cu alloy used for a heat exchanger, a brazing material made of an Al—Si alloy, or a brazing material made of an Al—Si alloy can be used. It is made of a clad material in which a sacrificial material made of an Al—Zn-based alloy is clad.

Further, as described above, the aluminum alloy plate for the cap material contains a plurality of elements because the aluminum scrap material is used as the main raw material. Specifically, the aluminum alloy plate for the cap material has Si: 0.9% by mass or more and 1.6% by mass or less, Fe: 0.2% by mass or more and 0.6% by mass or less, and Cu: 0.15% by mass. 0.5% by mass or less, Mn: 0.6% by mass or more and 1.1% by mass or less, Mg: 0.04% by mass or more and 0.2% by mass or less, Zn: 0.2% by mass or more and 0.6% by mass % Or less, Cr: less than 0.05% by mass, Ti: less than 0.1% by mass, Zr: less than 0.06% by mass, and the balance consists of Al and unavoidable impurities.

“Si” 0.9% by mass or more and 1.6% by mass or less Si contributes to the improvement of the tensile strength of the aluminum alloy plate for cap material. Specifically, Si forms an intermetallic compound together with Mg and the like contained at the same time, and improves tensile strength by solid solution hardening action, dispersion hardening action and precipitation hardening action.
If the Si content is less than 0.9% by mass, the tensile strength decreases, the ratio of scrap material that can be used as a raw material decreases, and if it exceeds 1.6% by mass, the ratio of intermetallic compounds increases. As a result, the tensile strength becomes too high and the workability is lowered.

"Fe" 0.2% by mass or more and 0.6% by mass or less Fe contributes to the improvement of the tensile strength of the aluminum alloy plate for the cap material. Specifically, Fe increases the amount of precipitation of the Al-Mn-Fe-based intermetallic compound and refines the crystal to improve the tensile strength.
When the Fe content is less than 0.2% by mass, the amount of the intermetallic compound precipitated is small, the crystals cannot be refined, the tensile strength is lowered, and aluminum scrap that can be used as a raw material is used. The ratio of wood decreases. On the other hand, if the Fe content exceeds 0.6% by mass, the tensile strength becomes too high and the workability deteriorates.

"Cu" 0.15% by mass or more and 0.5% by mass or less Cu contributes to the improvement of the tensile strength of the aluminum alloy plate for cap material. Specifically, Cu forms an intermetallic compound together with Mg and the like contained at the same time as Si, and improves tensile strength by solid solution hardening action, dispersion hardening action and precipitation hardening action.
If the Cu content is less than 0.15% by mass, sufficient tensile strength cannot be obtained, and the proportion of aluminum scrap material that can be used as a raw material decreases, and if it exceeds 0.5% by mass, the tensile strength is high. It becomes too much and the workability is lowered.

“Mn” 0.6% by mass or more and 1.1% by mass or less Mn contributes to the improvement of the tensile strength of the aluminum alloy plate for cap material. Specifically, Mn forms an Al—Mn—Fe-based intermetallic compound and exhibits a dispersion hardening action by forming a crystallization layer and a dispersion layer, thereby improving tensile strength.
When the Mn content is less than 0.6% by mass, the amount of the intermetallic compound precipitated is small, and sufficient curing characteristics are obtained, so that the tensile strength is lowered and when the cap material is processed. In addition to lowering the compressive strength of the aluminum scrap material, the ratio of aluminum scrap material that can be used as a raw material is reduced. On the other hand, if the Mn content exceeds 1.1% by mass, the ratio of the intermetallic compound increases, so that the tensile strength becomes too high and the workability deteriorates.

"Mg" 0.04% by mass or more and 0.2% by mass or less Mg contributes to the improvement of the tensile strength of the aluminum alloy plate for the cap material. Specifically, Mg has a solid solution hardening action, enhances work hardening during rolling, and exerts dispersion hardening action and precipitation hardening action by coexisting with Si and Cu to improve tensile strength. Let me.
If the Mg content is less than 0.04% by mass, sufficient tensile strength cannot be obtained, and the proportion of aluminum scrap material that can be used as a raw material decreases. And the tensile strength becomes too high due to the precipitation hardening action, and the workability is lowered.

"Zn" 0.2% by mass or more and 0.6% by mass or less Zn contributes to the improvement of the tensile strength of the aluminum alloy plate for cap material. Specifically, Zn improves the tensile strength by refining the precipitates of Mg, Si, and Cu.
If the Zn content is less than 0.2% by mass, the effect of miniaturization cannot be sufficiently obtained, so that there is a possibility of causing molding defects when processing into a cap material, and it can be used as a raw material. The ratio of aluminum scrap material decreases. On the other hand, if the Zn content exceeds 0.6% by mass, the tensile strength becomes too high and the workability deteriorates.

“Cr” less than 0.05% by mass Cr is a substance that may be contained in aluminum scrap materials for heat exchangers. If the Cr content is 0.05% by mass or more, the tensile strength becomes too high and the workability deteriorates.

"Ti" Less than 0.1% by mass Ti is a substance that is likely to be contained in aluminum scrap materials for heat exchangers. If the Ti content is 0.1% by mass or more, the surface of the aluminum alloy plate for the cap material becomes rough.

"Zr" less than 0.06% by mass Zr is a substance that may be contained in aluminum scrap material for heat exchangers. If the Zr content is 0.06% by mass or more, the tensile strength of the aluminum alloy plate for the cap material becomes too high, and the workability deteriorates.

Each of the above-mentioned Cr, Ti, and Zr is an irreversible element contained in scrap for heat exchangers, but when each of the above-mentioned upper limit values is exceeded, a coarse intermetallic compound is formed, and press and punching are performed. This is not preferable because it causes wear of the mold. That is, it is preferable that the aluminum alloy plate for the cap material does not contain Cr, Ti and Zr.

The aluminum alloy plate for a cap material having such a composition has a thickness of 0.20 mm or more and 0.26 mm or less, a tensile strength of 150 MPa or more and 250 MPa or less, a proof stress of 140 MPa or more and 240 MPa or less, and an ear ratio of 6% or less. is there.
If the tensile strength is less than 150 MPa or the proof stress is less than 140 MPa, the pressure resistance of the cap material is insufficient, and if the tensile strength exceeds 250 MPa or the proof stress exceeds 240 MPa, the workability may deteriorate and molding defects may occur. There is. Further, since the ear ratio when processed into the cap material is less than 6%, it is possible to suppress the trim chipping of the cap material and the distortion during printing on the cap material.

The "ear ratio" is a value derived from the average value of the height of the peak and the average value of the height of the valley formed on the side surface (tip portion) of the cylindrical portion by the following formula.
(Equation) Ear ratio (%) = (Average value of mountain height-Average value of valley height) / Average value of valley height x 100

[Manufacturing method of aluminum alloy plate for cap material]
The aluminum alloy plate for the cap material is manufactured by the following procedure. First, for aluminum alloys in the above composition range containing 60% by mass or more of aluminum scrap material, melt casting treatment, homogenization treatment, hot rolling treatment, complete softening annealing treatment, cold rolling treatment, intermediate annealing treatment, It is manufactured by performing the final cold rolling treatment and the final annealing treatment in this order. Hereinafter, a specific description will be given.

[Dissolution casting]
Si containing 60% by mass or more of aluminum scrap material: 0.9% by mass or more and 1.6% by mass or less, Fe: 0.2% by mass or more and 0.6% by mass or less, Cu: 0.15% by mass or more and 0 .5% by mass or less, Mn: 0.6% by mass or more and 1.1% by mass or less, Mg: 0.04% by mass or more and 0.2% by mass or less, Zn: 0.2% by mass or more and 0.6% by mass or less , Cr: less than 0.05% by mass, Ti: less than 0.1% by mass, Zr: less than 0.06% by mass, and the balance is composed of Al and unavoidable impurities. To do. Then, the molten aluminum alloy is cast by a semi-continuous casting method (DC casting).
The casting method is not limited to the semi-continuous casting method, and other conventional methods such as the continuous casting method may be used.

[Homogenization treatment]
The ingot obtained by the semi-continuous casting method is homogenized for the purpose of removing inhomogeneous structures such as segregation. Due to the high-temperature homogenization treatment, additive elements supersaturated and solid-solved in the matrix during casting are precipitated as intermetallic compounds. Since the size and the amount of dispersion of the precipitated intermetallic compound are affected by the temperature and time of the homogenization treatment, it is necessary to select the heat treatment conditions according to the type of the additive element.
For example, since an aluminum alloy containing an aluminum scrap material for a heat exchanger has the above composition, the obtained ingot is homogenized at a temperature of 500 ° C. or higher and a melting point or lower for 2 to 10 hours.

[Hot rolling]
Hot rolling is performed on the ingot that has been homogenized. This hot rolling is started at a high temperature of about 500 ° C. By this hot rolling, a first plate material having an ingot having a thickness of 2.0 mm or more and 3.6 mm or less is formed.
If the thickness of the first plate material is less than 2.0 mm, rolling cannot be performed with a uniform thickness, and if it exceeds 3.6 mm, the productivity decreases.

[Complete softening annealing]
Here, since the first plate material (aluminum alloy) of the present embodiment has a large amount of Si component and is a material that is difficult to be recrystallized, the structure after the hot rolling process is dominated by the rolled texture, and the final structure is dominated. The ear ratio of the board increases. Therefore, in the present embodiment, the first plate material after the hot rolling process is completely softened and annealed. By carrying out this complete softening and annealing treatment, the first plate material that has been hot-rolled is completely recrystallized, and a structure with random orientations is formed, which contributes to lowering the ears. Therefore, it is preferable as the pretreatment for cold rolling described below. The complete softening annealing treatment is carried out, for example, by using a batch annealing furnace at a temperature of 300 ° C. or higher and lower than the melting point for 1 hour or longer and 6 hours or lower, or using a continuous annealing furnace at a temperature of 400 ° C. or higher and 550 ° C. or lower. It is carried out by performing a process of holding for seconds or more and 60 seconds or less.
In the batch annealing treatment using the batch annealing furnace, if the annealing temperature is less than 300 ° C., or in the continuous annealing treatment using the continuous annealing furnace, the recrystallization becomes insufficient when the continuous annealing temperature is less than 400 ° C. The rate is high.

In the present embodiment, the first plate material after hot rolling is subjected to complete softening annealing, but the present invention is not limited to this, and the present invention is applied to the first plate material after hot rolling before performing complete softening annealing. Cold rolling corresponding to the second cold rolling (for example, rolling reduction of 10% or more and 40% or less, 1 pass) may be added. In this case, the strain introduced by the mild cold rolling serves as a driving force to promote recrystallization. The reduction rate of the second cold rolling is set to be smaller than the reduction rate of the cold rolling (first cold rolling) described later, and when the reduction rate of the second cold rolling is less than 10%, the above drive The force may be insufficient, and if it exceeds 40%, the rolled texture may be excessively developed, the texture in a random orientation may not be obtained even after recrystallization, and the ear ratio may be increased.

[Cold rolling (first cold rolling)]
Cold rolling is carried out on the first plate material after the complete softening and annealing treatment. This cold rolling method is not particularly limited, but can be carried out, for example, by passing the first plate material through a rolling mill.

[Intermediate annealing]
Intermediate annealing is performed on the plate material after cold rolling. This intermediate annealing is carried out for the purpose of lowering the ears by recrystallization of the rolled texture generated by cold rolling and adjusting the strength by solid solution hardening, and the temperature is set to 400 ° C. or higher and 550 ° C. or lower, and the holding time is set. Is 5 seconds or more and 30 seconds or less. In the present embodiment, the rolled texture is recrystallized in two steps, complete softening annealing and intermediate annealing, thereby reliably forming a structure in a random orientation, which contributes to lower ears.
If the intermediate annealing temperature is less than 400 ° C. or the holding time is less than 5 seconds, the tensile strength of the aluminum alloy plate for the cap material is insufficient. On the other hand, when the intermediate annealing temperature exceeds 550 ° C. or the holding time exceeds 30 seconds, the productivity of the aluminum alloy plate for the cap material decreases.

[Final cold post]
The final cold rolling is carried out on the plate material after the intermediate annealing treatment. In this final cold rolling, the final cold rolling ratio is 30% or more and 70% or less, and the second plate material is rolled to have a thickness of 0.20 mm or more and 0.26 mm or less. The temperature of the final cold spreading process is set to 100 ° C. to 160 ° C.
If the final cold spreading ratio is less than 30%, the tensile strength becomes low, and if it exceeds 70%, the tensile strength becomes too high and the ear ratio may exceed 6%. Further, if the second plate material (final thickness of the aluminum alloy plate for the cap material) is less than 0.20 mm, the pressure resistance performance as the cap material cannot be sufficiently maintained, and if it exceeds 0.26 mm, it is wound with an appropriate load. It cannot be tightened.

[Final annealing]
Then, the second plate material is subjected to final annealing at 180 ° C. or higher and 260 ° C. or lower for 3 hours or more and 5 hours or less. This final annealing is carried out in order to make the tensile strength of the aluminum alloy plate for the cap material 150 MPa or more and 250 MPa or less.
If the final annealing temperature is less than 180 ° C., the workability is lowered, and if it exceeds 260 ° C., the tensile strength is lowered. Further, if the holding time of the final annealing at the above temperature is less than 3 hours, the workability is lowered, and if it exceeds 5 hours, the productivity of the aluminum alloy plate for the cap material is lowered.

The second plate material after the final annealing treatment is the aluminum alloy plate for the cap material of the present embodiment. The aluminum alloy plate for cap material produced by such a manufacturing method has a plate thickness of 0.20 mm or more and 0.26 mm or less, a tensile strength of 150 MPa or more and 250 MPa or less, a proof stress of 140 MPa or more and 240 MPa or less, and an ear ratio. Is 6% or less. Further, since the aluminum alloy plate for the cap material can be manufactured from the aluminum alloy containing 60% by mass or more of the aluminum scrap material, the environmental load can be reduced.

In the present embodiment, since the plate thickness is set to 0.20 mm or more and 0.26 mm or less, it has sufficient pressure resistance and can be wound with an appropriate load. If the plate thickness is less than 0.20 mm, sufficient pressure resistance as a cap material cannot be maintained, and if it exceeds 0.26 mm, winding cannot be performed with an appropriate load. Further, since the tensile strength of the aluminum alloy plate for the cap material is set to 150 MPa or more and 250 MPa or less, the pressure resistance strength of the cap material can be increased. If the tensile strength is less than 150 MPa, the pressure resistance of the cap material becomes low and the necessary mechanical properties cannot be obtained. If the tensile strength exceeds 250 MPa, the bottle can is covered with the cap material and threaded. The required molding load increases. Further, since the proof stress is set to 140 MPa or more and 240 MPa or less, it has sufficient compressive strength and is excellent in workability. As with the tensile strength, if the proof stress is less than 140 MPa, the withstand voltage strength is insufficient, and if it exceeds 240 MPa, the workability is lowered and molding defects may occur. Further, since the ear ratio of the aluminum alloy plate for the cap material is less than 6%, it is possible to suppress the trim chipping of the cap material and the distortion during printing on the cap material, and it is possible to improve the workability.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

The aluminum alloys for cap materials of Examples 1 to 6 and Comparative Examples 1 to 3 were produced by the methods shown below, and the tensile strength and ear ratio of each of the obtained samples were measured. This will be described in detail below.
The aluminum alloys used as the raw materials of Examples 1 to 6 and Comparative Examples 1 to 3 had different compounding ratios of aluminum scrap materials for heat exchangers. Specifically, for Examples 1, 4 to 6 and Comparative Example 2, an aluminum alloy made of 100% aluminum scrap material for a heat exchanger was used, and for Example 2 and Comparative Example 3, 80% heat exchange was performed. An aluminum alloy containing a dexterous aluminum scrap material is used, in Example 3, an aluminum alloy containing a 60% heat exchanger aluminum scrap material is used, and in Comparative Example 1, a 40% heat exchanger aluminum scrap material is contained. An aluminum alloy was used. The composition of each of these aluminum alloys is as shown in Table 1.

The aluminum alloys of Examples 1 to 6 and Comparative Examples 1 to 3 were melted to form a molten aluminum alloy, which was cast by semi-continuous casting. The ingot obtained by the semi-continuous casting method was homogenized at 565 ° C. for 5 hours and hot-rolled to form a first plate having a thickness of 2.2 to 3.2 mm. In Examples 1 to 4 and Comparative Examples 1 and 2, the first plate material was completely softened and annealed at 360 ° C. for 4 hours, and cold rolling (first cold rolling) was carried out. Further, in Examples 5 and 6, after hot rolling, light cold rolling (second cold rolling) was performed at the rolling reduction ratio shown in Table 2, followed by complete softening annealing, and cold rolling (first cold rolling). Rolling between) was carried out. On the other hand, in Comparative Example 3, cold rolling (first cold rolling) was carried out without completely softening and annealing the first plate material. Then, intermediate annealing was performed on the plate material after cold rolling. The temperature of this intermediate annealing is as shown as the CAL temperature in Table 2, and the holding time was set to 20 seconds. Then, the plate material after the intermediate annealing was finally cold-rolled at 120 ° C. at the final cold spreading ratio shown in Table 2 to form a second plate material having a thickness of 0.230 mm. The second plate material was finally annealed at the temperatures shown in Table 1 for 4 hours to prepare each sample.

(Measurement of tensile strength and proof stress)
The tensile strength and proof stress were evaluated by a method according to JIS Z2241. Specifically, a sample was cut out from each of the obtained samples in parallel with the rolling direction to prepare a test piece of JIS No. 5, a tensile test was carried out at room temperature, and the tensile strength and proof stress (MPa) were measured.

(Measurement of ear rate)
Each of the obtained samples was painted and printed by a conventional method, and a cylindrical deep drawing test was carried out using an Eriksen tester. The processing conditions were a punch diameter of 33 mm (flat head punch), a die inner diameter of 33.7 mm, a drawing ratio of 1.75, a clearance between the punch and the die of 0.35 mm, and a wrinkle suppression pressure of 5 kN. The height of the side wall (height of the cylindrical portion) of each of these cap materials was measured with a digital micrometer at every 2 ° angle with respect to the rolling direction over the entire circumference, and the ear ratio was calculated by the following formula.
(Equation) Ear ratio (%) = (Average value of mountain height-Average value of valley height) / Average value of valley height x 100
The measurement results described above are as shown in Table 2.

From Tables 1 and 2, Examples 1 to 6 are made from an aluminum alloy containing 60% or more of aluminum scrap material for a heat exchanger, and the first plate material is completely softened and annealed, and this intermediate annealing is performed. The temperature was 400 ° C or higher and 550 ° C or lower, the final cooling rate was 30% or higher and 70% or lower, and the final annealing temperature was 180 ° C or higher and 260 ° C or lower. Below, and the ear rate was 6% or less.
On the other hand, in Comparative Example 1, since the aluminum alloy used as a raw material contains only 40% of aluminum scrap material for a heat exchanger, the contents of the essential elements Si, Fe, Cu, Mn, and Zn are all low. Therefore, the tensile strength was as low as 144 MPa. Further, in Comparative Example 2, since the final cold spreading ratio was as high as 80%, the tensile strength became too high and the ear ratio also exceeded 6%. Further, in Comparative Example 3, since the first plate material was cold-rolled without being completely softened and annealed, the ear ratio was as high as 7.3%.

Claims (3)

Si: 0.9% by mass or more and 1.6% by mass or less, Fe: 0.2% by mass or more and 0.6% by mass or less, Cu: 0.15% by mass or more and 0.4% by mass or less, Mn: 0.6 Mass% or more and 1.1 mass% or less, Mg: 0.04 mass% or more and 0.2 mass% or less, Zn: 0.2 mass% or more and 0.6 mass% or less, Cr: less than 0.05 mass%, Ti : Less than 0.1% by mass, Zr: Less than 0.06% by mass, the balance is composed of Al and unavoidable impurities, plate thickness is 0.20 mm or more and 0.26 mm or less, tensile strength is 150 MPa or more and 250 MPa or less, strength An aluminum alloy plate for a cap material, which is 140 MPa or more and 240 MPa or less and has an ear ratio of 6% or less. Contains 60% by mass or more of aluminum scrap material, Si: 0.9% by mass or more and 1.6% by mass or less, Fe: 0.2% by mass or more and 0.6% by mass or less, Cu: 0.15% by mass or more and 0 .4% by mass or less, Mn: 0.6% by mass or more and 1.1% by mass or less, Mg: 0.04% by mass or more and 0.2% by mass or less, Zn: 0.2% by mass or more and 0.6% by mass or less , Cr: less than 0.05% by mass, Ti: less than 0.1% by mass, Zr: less than 0.06% by mass, and the balance is Al and unavoidable impurities. To form a first plate material having a thickness of 2.0 mm or more and 3.6 mm or less, the first plate material is completely softened and annealed, and then the first cold rolling is performed. After the first cold rolling, intermediate annealing is performed at 400 ° C. or higher and 550 ° C. or lower for 5 seconds or longer and 30 seconds or shorter, and then cold rolling is performed at a final cold rolling ratio of 30% or more and 70% or less to a thickness of 0.20 mm or more. A method for producing an aluminum alloy plate for a cap material, which comprises forming a second plate material of 0.26 mm or less and finally subjecting the second plate material to final annealing at 180 ° C. or higher and 260 ° C. or lower for 3 hours or more and 5 hours or less. The first plate material formed by the homogenization treatment and the hot rolling is subjected to the second cold rolling with a reduction ratio of 10% or more and 40% or less, and then the complete softening annealing is performed. The method for manufacturing an aluminum alloy plate for a cap material according to claim 2.