JP7432352B2 - Aluminum alloy plate for cap material and its manufacturing method - Google Patents

Description

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

Aluminum or aluminum alloy is a material with excellent recyclability. It is known that by reusing this aluminum or aluminum alloy scrap material to manufacture aluminum alloy, it is possible to significantly suppress the amount of _CO2 generated and reduce the environmental impact compared to the case of using aluminum ingots. There is. As aluminum alloy plates made of recycled scrap materials, for example, 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, and Mn: 1% by 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, and W is 0.015% or more and 0.5% or less, and the balance is Al and impurities. Consisting of

The aluminum alloy plate described in Patent Document 1 is manufactured by subjecting an aluminum alloy ingot having the above composition to homogenization heat treatment at a temperature of 500°C or higher and below the melting point, followed by an average cooling rate of 40°C/h from 500°C to 350°C. above or less than 100°C/h, and after cooling to a temperature of 200°C or less, start hot rolling after reheating to a temperature of 300 to 450°C, and set the end temperature of this hot rolling to 170 to 300°C. A hot-rolled plate is produced, and the hot-rolled plate is then cold rolled without being annealed in advance to produce a cold-rolled plate, and this cold-rolled plate is subjected to solution treatment and treatment at a temperature of 560°C or higher. Manufactured by quenching. As a result, the aluminum alloy plate described in Patent Document 1 has an average number density of 3,000 to 20,000 particles/mm ² of all dispersed particles with a size of 0.5 μm or more, and the size of these measured dispersed particles is X μm. In the coordinate with axis, number density Y pieces/mm ² as the vertical axis, dispersed particles with a size of X of 10 μm or less are expressed as Y = Aexp (BX), where A/B is 1000. ~40,000, and B is in the range of 0.5~2.

Further, the aluminum alloy plate described in Patent Document 2 includes Si: 0.5 to 1.4 mass%, Fe: 0.3 to 1.1 mass%, Cu: 0.1 to 0.3 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 remainder: Al and impurities, with Zn as an impurity being 1%. 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 produced by continuously casting a molten aluminum alloy having the above composition into a slab with a thickness of 3 to 10 mm using a continuous thin slab casting machine, and then subjecting the slab to homogenization treatment and hot rolling. After winding directly onto a coil without applying heat, cold rolling is performed, the coil is inserted into a batch furnace, and intermediate annealing is performed at a holding temperature of 430 to 510°C for 0.5 to 12 hours. It is manufactured by cold rolling at a cold rolling rate 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 grain size of recrystallized grains of less than 30 μm. It is a cold rolled annealed material.

Japanese Patent Application Publication No. 2007-169740 JP2015-96650A

By the way, the aluminum alloys described in Patent Documents 1 and 2 are formed for use in automobile bodies, and it is difficult to use them as they are as aluminum alloys for cap materials. For this reason, there is a demand for an aluminum alloy plate for cap material that is suitable for processing using scrap materials as a main component.

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

As a result of intensive research, these researchers analyzed the components of scrap materials generated at aluminum rolling mills, examined in detail the effects of alloying elements that are abundant in scrap materials, and determined the selection of alloying component ranges and the subsequent By appropriately controlling the combination of manufacturing conditions, we have discovered an aluminum alloy material for cap material that can be used for bottle caps.

That is, the aluminum alloy plate for cap material of the present invention contains 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. 0.5 mass% or more, 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% by mass, Ti: less than 0.1% by mass, Zr: less than 0.06% by mass, with the remainder consisting of Al and unavoidable impurities, and the plate thickness is 0.20mm or more. .26 mm or less, the tensile strength is 150 MPa or more and 250 MPa or less, the yield strength is 140 MPa or more and 240 MPa or less, and the selvedge 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 this plate thickness is less than 0.20 mm, it will not be able to maintain sufficient pressure resistance as a cap material, and if it exceeds 0.26 mm, it will not be possible to seam 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 will be insufficient, and if it exceeds 250 MPa, workability may deteriorate and molding defects may occur. Further, the proof strength is set to 140 MPa or more and 240 MPa or less. Similarly to the tensile strength, if the yield strength is less than 140 MPa, the compressive strength will be insufficient, and if it exceeds 240 MPa, the workability will decrease and molding defects may occur. Further, since the selvage ratio is less than 6%, trim chipping of the cap material and distortion during printing on the cap material can be suppressed, and processability can be improved.
In addition, the "edge ratio" is a value derived from the average height of the peaks and the average height of the valleys formed on the side surface (tip part) of the cylindrical part of the cap material using the following formula. .
(Formula) Ear rate (%) = (Average peak height - Average valley height) / Average valley height x 100

Si contributes to improving the tensile strength of the aluminum alloy plate for the cap material, and if it is less than 0.9% by mass, the tensile strength will decrease, and if it exceeds 1.6% by mass, the tensile strength will be too high, and it will cause problems between metals. The proportion of compounds increases.
Fe contributes to improving 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 intermetallic compounds increases.
Cu contributes to improving 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 improving 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 The proportion of compounds increases.
Mg contributes to improving the tensile strength of the aluminum alloy plate for the cap material, and when it is less than 0.04% by mass, the tensile strength decreases, and when it exceeds 0.2% by mass, the tensile strength becomes too high.
Zn contributes to improving the tensile strength of the aluminum alloy plate for the cap material, and if it is less than 0.2 mass%, it may cause molding defects during processing (forming) of the cap material, and 0.6 mass% If it exceeds , the tensile strength becomes too high.

Cr does not necessarily need to be contained; 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 need 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 capping material will become rough.
Zr does not necessarily need 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 includes aluminum scrap material of 60% by mass or more, Si: 0.9% by mass or more and 1.6% by mass or less, Fe: 0.2% by mass or more and 0.5% by mass or less. 6 mass% or less, Cu: 0.15 mass% or more and 0.5 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, Contains 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 remainder is Al and unavoidable. After melting and casting an aluminum alloy containing impurities, a first plate material with a thickness of 2.0 mm or more and 3.6 mm or less is formed by performing homogenization treatment and hot rolling, and the first plate material is completely softened and annealed. After performing a first cold rolling, after the first cold rolling, an intermediate annealing is performed at a temperature of 400 ° C. or more and 550 ° C. or less for 5 seconds or more and 30 seconds or less, and then a final cold rolling ratio of 30% or more and 70 % or less to form a second plate material having a thickness of 0.20 mm or more and 0.26 mm or less, and final annealing is performed on the second plate material 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 yield strength can be 140 MPa or more and 240 MPa, and the selvedge ratio can be 6% or less.
If the thickness of the first plate material is less than 2.0 mm, it will not be possible to roll it to a uniform thickness, and if it exceeds 3.6 mm, productivity will decrease. In addition, if the second plate material (the final thickness of the aluminum alloy plate for cap material) is less than 0.20 mm, it will not be able to maintain sufficient pressure resistance as a cap material, and if it exceeds 0.26 mm, it will be seamed with an appropriate load. become unable to do so.

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

Further, the first plate material formed by the homogenization treatment and the hot rolling is subjected to a second cold rolling at a reduction rate of 10% or more and 40% or less, and then the complete softening annealing is performed. It may be applied.
When recrystallization progresses too much in the hot rolling process, the strain introduced by mild cold rolling (second cold rolling) can serve as a driving force to promote recrystallization.
Note that if the rolling reduction is less than 10%, the above driving force may not be sufficient, and if it exceeds 40%, the rolling texture will develop excessively and the randomly oriented structure will remain even after recrystallization. This may result in a higher rate of hearing.

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

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

[Structure of aluminum alloy plate for cap material]
The aluminum alloy plate for cap material becomes a cap material to be attached to a bottle can such as an aluminum bottle by being subjected to a drawing process or the like. This aluminum alloy plate for cap material is formed from an aluminum alloy whose main raw material is scrap material. Specifically, the aluminum alloy used as the aluminum alloy plate for the cap material contains 60% by mass or more of scrap material, and may be entirely made of scrap material.
In addition, such scrap materials are generated in aluminum rolling factories, and for example, a core material made of an Al-Mn-Cu alloy used in a heat exchanger is mixed with a brazing material made of an Al-Si alloy or a core material made of an Al-Mn-Cu alloy. It consists of a cladding material clad with a sacrificial material made of an Al--Zn alloy.

Further, as described above, the aluminum alloy plate for the cap material uses aluminum scrap material as the main raw material, and thus contains a plurality of elements. Specifically, the aluminum alloy plate for the cap material contains 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. 0.5 mass% or more, 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% %, Cr: less than 0.05% by mass, Ti: less than 0.1% by mass, Zr: less than 0.06% by mass, and the remainder consists of Al and inevitable impurities.

"Si" 0.9% by mass or more and 1.6% by mass or less Si contributes to improving the tensile strength of the aluminum alloy plate for the cap material. Specifically, Si forms an intermetallic compound together with Mg and the like contained at the same time, and improves the tensile strength by solid solution hardening, dispersion hardening, and precipitation hardening.
If the Si content is less than 0.9% by mass, the tensile strength will decrease and the ratio of scrap materials that can be used as raw materials will decrease, and if it exceeds 1.6% by mass, the proportion of intermetallic compounds will increase. By doing so, the tensile strength becomes too high and the workability decreases.

"Fe" 0.2% by mass or more and 0.6% by mass or less Fe contributes to improving the tensile strength of the aluminum alloy plate for the cap material. Specifically, Fe increases the amount of precipitated Al-Mn-Fe intermetallic compounds and refines the crystals, thereby improving the tensile strength.
If the Fe content is less than 0.2% by mass, the amount of intermetallic compounds precipitated will be small, crystals cannot be made finer, the tensile strength will be lower, and aluminum scrap can be used as a raw material. The proportion of wood decreases. On the other hand, when the content of Fe 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 improving the tensile strength of the aluminum alloy plate for the cap material. Specifically, like Si, Cu forms an intermetallic compound together with Mg and the like contained at the same time, and improves the tensile strength through solid solution hardening, dispersion hardening, and precipitation hardening.
If the Cu content is less than 0.15% by mass, sufficient tensile strength will not be obtained, and the proportion of aluminum scrap material that can be used as raw material will decrease, and if it exceeds 0.5% by mass, the tensile strength will be high. If it becomes too much, the workability will deteriorate.

"Mn" 0.6% by mass or more and 1.1% by mass or less Mn contributes to improving the tensile strength of the aluminum alloy plate for the cap material. Specifically, Mn forms an Al--Mn--Fe based intermetallic compound and serves as a crystallization layer and a dispersion layer to exhibit a dispersion hardening effect, thereby improving tensile strength.
If the Mn content is less than 0.6% by mass, the amount of intermetallic compounds precipitated will be small, and sufficient hardening properties will not be obtained, resulting in a decrease in tensile strength and when processed into a cap material. In addition to decreasing the compressive strength of aluminum, the proportion of aluminum scrap that can be used as raw material also decreases. On the other hand, if the Mn content exceeds 1.1% by mass, the proportion of the intermetallic compound increases, resulting in an excessively high tensile strength and poor workability.

"Mg" 0.04% by mass or more and 0.2% by mass or less Mg contributes to improving the tensile strength of the aluminum alloy plate for the cap material. Specifically, Mg has a solid solution hardening effect and increases work hardening during rolling, and when coexisting with Si and Cu, it exhibits dispersion hardening and precipitation hardening effects, improving tensile strength. let
If the content of Mg is less than 0.04% by mass, sufficient tensile strength cannot be obtained, and the ratio of aluminum scrap material that can be used as a raw material decreases, and if it exceeds 0.2% by mass, dispersion hardening occurs. The tensile strength becomes too high due to the precipitation hardening effect, resulting in poor workability.

"Zn" 0.2% by mass or more and 0.6% by mass or less Zn contributes to improving the tensile strength of the aluminum alloy plate for the cap material. Specifically, Zn improves tensile strength by making precipitates of Mg, Si, and Cu finer.
If the Zn content is less than 0.2% by mass, the effect of micronization will not be sufficiently obtained, which may cause molding defects when processing into cap material, and it may not be possible to use it as a raw material. The proportion of aluminum scrap material will decrease. On the other hand, if the Zn content exceeds 0.6% by mass, the tensile strength becomes too high and the workability decreases.

"Cr" less than 0.05% by mass Cr is a substance that may be contained in the aluminum scrap material 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 material for heat exchangers. When the Ti content is 0.1% by mass or more, roughness occurs on the surface of the aluminum alloy plate for cap material.

"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, resulting in poor workability.

In addition, each of the above-mentioned Cr, Ti, and Zr is an irreversible element contained in heat exchanger scrap, but if each of the above-mentioned upper limits is exceeded, a coarse intermetallic compound is formed and it is difficult to press or punch. This is undesirable because it may cause mold wear. In other words, it is better that the aluminum alloy plate for the cap material does not contain Cr, Ti, and Zr.

The aluminum alloy plate for 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 yield strength of 140 MPa or more and 240 MPa or less, and a selvedge ratio of 6% or less. be.
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 will be insufficient, and if the tensile strength is more than 250 MPa or the proof stress is more than 240 MPa, workability may decrease and molding defects may occur. There is. Furthermore, since the selvage ratio when processed into a cap material is less than 6%, trim chipping of the cap material and distortion during printing on the cap material can be suppressed.

The "edge ratio" is a value derived from the average height of the peaks and the average height of the valleys formed on the side surface (tip end) of the cylindrical portion using the following formula.
(Formula) Ear rate (%) = (Average peak height - Average valley height) / Average valley height x 100

[Method for manufacturing aluminum alloy plate for cap material]
The aluminum alloy plate for cap material is manufactured by the following procedure. First, an aluminum alloy having the above composition range containing 60% by mass or more of aluminum scrap material is subjected to melt casting treatment, homogenization treatment, hot rolling treatment, complete softening annealing treatment, cold rolling treatment, intermediate annealing treatment, It is manufactured by performing final cold rolling treatment and final annealing treatment in this order. This will be explained in detail below.

[Melt 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 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% by mass, Ti: less than 0.1% by mass, Zr: less than 0.06% by mass, and the balance consists of Al and inevitable impurities. do. Then, the molten aluminum alloy is cast by a semi-continuous casting method (DC casting).
Note that the casting method is not limited to the semi-continuous casting method, and other conventional methods such as a continuous casting method may be used.

[Homogenization processing]
The ingot obtained by semi-continuous casting is subjected to homogenization treatment to remove heterogeneous structures such as segregation. Due to the high-temperature homogenization treatment, the additive elements that were supersaturated in solid solution in the matrix during casting precipitate as intermetallic compounds. Since the size and amount of dispersion of the precipitated intermetallic compound are affected by the temperature and time of the homogenization treatment, it is necessary to select heat treatment conditions depending on the type of added element.
For example, since the aluminum alloy containing aluminum scrap material for a heat exchanger has the above composition, the obtained ingot is subjected to homogenization treatment at a temperature of 500° C. or higher and lower than the melting point for 2 to 10 hours.

[Hot rolling]
Hot rolling is performed on the homogenized ingot. This hot rolling is started at a high temperature of around 500°C. By this hot rolling, a first plate material whose ingot has a thickness of 2.0 mm or more and 3.6 mm or less is formed.
Note that if the thickness of the first plate material is less than 2.0 mm, it will not be possible to roll it to a uniform thickness, and if it exceeds 3.6 mm, productivity will decrease.

[Complete softening annealing]
Here, since the first plate material (aluminum alloy) of this embodiment has a large Si component and is a material that is difficult to recrystallize, the structure after hot rolling treatment is also dominated by the rolling texture, and the final The selvage rate of the board increases. Therefore, in this embodiment, complete softening annealing is performed on the first plate material after hot rolling treatment. By carrying out this complete softening annealing treatment, the hot-rolled first plate material is completely recrystallized, and a randomly oriented structure is formed, which contributes to a low profile. Therefore, it is preferable as a pretreatment for cold rolling described below. Complete softening annealing treatment is, for example, held at a temperature of 300°C or more and below the melting point using a batch annealing furnace for 1 hour or more and 6 hours or less, or held at a temperature of 400°C or more and 550°C or less using a continuous annealing furnace for 5 hours. This is carried out by performing a process of holding for more than 60 seconds.
In addition, in batch annealing treatment using a batch annealing furnace, if the annealing temperature is less than 300°C, or in continuous annealing treatment using a continuous annealing furnace, if the continuous annealing temperature is less than 400°C, recrystallization will be insufficient and the rate becomes higher.

In this embodiment, the first plate material after hot rolling is subjected to complete softening annealing, but the present invention is not limited to this. Cold rolling equivalent 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 mild cold rolling can serve as a driving force to promote recrystallization. The rolling reduction ratio of this second cold rolling is set smaller than the rolling ratio of cold rolling (first cold rolling) which will be described later, and if the rolling ratio of the second cold rolling is less than 10%, the above-mentioned drive The force may be insufficient, and if it exceeds 40%, the rolling texture will develop excessively, and even after recrystallization, a randomly oriented structure may not be obtained, and the selvedge ratio may increase.

[Cold rolling (first cold rolling)]
Cold rolling is performed on the first plate material after the complete softening 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 profile by recrystallizing the rolling texture generated by cold rolling and adjusting the strength by solid solution hardening. is set to be 5 seconds or more and 30 seconds or less. In this embodiment, the rolling texture is recrystallized in two stages: complete softening annealing and intermediate annealing, thereby reliably forming a randomly oriented texture, thereby contributing to lowering the radius.
In addition, when the temperature of intermediate annealing is less than 400 degreeC or the holding time is less than 5 seconds, the tensile strength of the aluminum alloy plate for cap materials will be insufficient. On the other hand, if the intermediate annealing temperature exceeds 550° C. or the holding time exceeds 30 seconds, the productivity of the aluminum alloy plate for cap material decreases.

[Final cold rolling]
Final cold rolling is performed on the plate material after the intermediate annealing treatment. In this final cold rolling, the final cold rolling rate is set to 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. Further, the temperature of the final cold rolling treatment is set at 100°C to 160°C.
In addition, if the final cold rolling ratio is less than 30%, the tensile strength will be low, and if it exceeds 70%, the tensile strength will be too high and the edge ratio may exceed 6%. Additionally, if the second plate material (the final thickness of the aluminum alloy plate for cap material) is less than 0.20 mm, it will not be able to maintain sufficient pressure resistance as a cap material, and if it exceeds 0.26 mm, it will not be able to be wound with an appropriate load. It becomes impossible to tighten.

[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.
Note that if the final annealing temperature is less than 180°C, the workability will decrease, and if it exceeds 260°C, the tensile strength will decrease. Further, if the holding time at the above temperature during final annealing is less than 3 hours, the workability will be reduced, and if it exceeds 5 hours, the productivity of the aluminum alloy plate for cap material will be reduced.

The second plate material after this final annealing process becomes the aluminum alloy plate for cap material of this embodiment. The aluminum alloy plate for cap material manufactured by such a manufacturing method 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 yield strength of 140 MPa or more and 240 MPa or less, and a selvage ratio of 140 MPa or more and 240 MPa or less. will be less than 6%. Furthermore, since the aluminum alloy plate for the cap material can be manufactured from an aluminum alloy containing 60% by mass or more of aluminum scrap material, the environmental load can be reduced.

In this 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 allows the cap material to be seamed with an appropriate load. Note that if the plate thickness is less than 0.20 mm, it will not be able to maintain sufficient pressure resistance as a cap material, and if it exceeds 0.26 mm, it will not be possible to seam with an appropriate load. Moreover, 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 will be low and the necessary mechanical properties will not be obtained, and if the tensile strength exceeds 250 MPa, it will be difficult to thread the cap material over the bottle can. The required molding load increases. Furthermore, since the yield strength is set to 140 MPa or more and 240 MPa or less, it has sufficient pressure resistance strength and is excellent in workability. Note that, similarly to the tensile strength, if the yield strength is less than 140 MPa, the compressive strength will be insufficient, and if it exceeds 240 MPa, the workability will decrease and molding defects may occur. Furthermore, since the selvage ratio of the aluminum alloy plate for the cap material is less than 6%, trim chipping of the cap material and distortion during printing on the cap material can be suppressed, and workability can be improved.

Note that the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention.

Aluminum alloys for cap materials of Examples 1 to 6 and Comparative Examples 1 to 3 were manufactured by the method shown below, and the tensile strength and selvedge ratio of each sample obtained were measured. This will be explained in detail below.
The aluminum alloys used as raw materials for Examples 1 to 6 and Comparative Examples 1 to 3 had different blending ratios of aluminum scrap material 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, an 80% heat exchanger was used. For example 3, an aluminum alloy containing 60% heat exchanger aluminum scrap material was used; for comparative example 1, an aluminum alloy containing 40% heat exchanger aluminum scrap material was used. 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 produce molten aluminum alloys, which were 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 material 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 subjected to complete softening annealing at 360° C. for 4 hours, and then cold rolled (first cold rolling). In addition, in Examples 5 and 6, after hot rolling, slight cold rolling (second cold rolling) was performed at the rolling reduction ratio shown in Table 2, complete softening annealing was performed, and cold rolling (first cold rolling) was performed. Inter-rolling) was carried out. On the other hand, in Comparative Example 3, the first plate material was cold rolled (first cold rolling) without being completely softened and annealed. Then, intermediate annealing was performed on the plate material after cold rolling. The temperature of this intermediate annealing was as shown in Table 2 as CAL temperature, and the holding time was 20 seconds. Then, the plate material after the intermediate annealing was subjected to final cold rolling at 120° C. and the final cold rolling rate shown in Table 2 to form a second plate material having a thickness of 0.230 mm. This second plate material was subjected to final annealing for 4 hours at the temperature shown in Table 1 to obtain each sample.

(Measurement of tensile strength and yield strength)
The tensile strength and yield strength were evaluated by a method according to JIS Z2241. Specifically, a JIS No. 5 test piece was prepared by cutting out a sample parallel to the rolling direction from each sample obtained, and a tensile test was conducted at room temperature to measure the tensile strength and proof stress (MPa).

(Measurement of ear rate)
Each of the obtained samples was coated and printed using a conventional method, and a cylindrical deep drawing test was conducted using an Erichsen 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 suppressing pressure of 5 kN. The side wall height (height of the cylindrical portion) of each of these cap materials was measured with a digital micrometer over the entire circumference at every 2° angle with respect to the rolling direction, and the selvedge ratio was calculated using the following formula.
(Formula) Ear rate (%) = (Average peak height - Average valley height) / Average valley height x 100
The measurement results explained above are as shown in Table 2.

From Tables 1 and 2, in Examples 1 to 6, aluminum alloys containing 60% or more of aluminum scrap material for heat exchangers were used as raw materials, and the first plate material was subjected to complete softening annealing, and this intermediate annealing was performed. The temperature was 400°C or more and 550°C or less, the final cold rolling rate was 30% or more and 70% or less, and the final annealing temperature was 180°C or more and 260°C or less, so the tensile strength was 150MPa or more and 250MPa or less, and the yield strength was 140MPa or more and 240MPa. and below, and the ear rate was reduced to 6% or less.
On the other hand, in Comparative Example 1, the raw material aluminum alloy contains only 40% aluminum scrap material for heat exchangers, so the content of the essential elements Si, Fe, Cu, Mn, and Zn is low. Therefore, the tensile strength was as low as 144 MPa. Further, in Comparative Example 2, the final cold rolling ratio was as high as 80%, so the tensile strength was too high and the edge ratio also exceeded 6%. Furthermore, in Comparative Example 3, the first plate material was cold rolled without being completely softened and annealed, so the selvage ratio was as high as 7.3%.

Claims (3)

Si: 0.9 mass% or more and 1.6 mass% or less, Fe: 0.2 mass% or more and 0.6 mass% or less, Cu: 0.15 mass% or more and 0.4 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 remainder consists 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, yield strength An aluminum alloy plate for a cap material, characterized in that the pressure is 140 MPa or more and 240 MPa or less, and the selvage ratio shown below is 6% or less.
The selvage ratio is the average height of the peaks and the height of the valleys formed on the side surface of the cylindrical part produced with a punch diameter of 33 mm, a die inner diameter of 33.7 mm, a drawing ratio of 1.75, and a wrinkle suppression pressure of 5 kN. This is a value derived from the average value of the thickness using the following formula.
(Formula) Ear rate (%) = (Average peak height - Average valley height) / Average valley height x 100 A method for manufacturing an aluminum alloy plate for a cap material according to claim 1,
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 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% by mass, Ti: less than 0.1% by mass, and Zr: less than 0.06% by mass, after melting and casting an aluminum alloy with the remainder consisting of Al and unavoidable impurities, and then homogenized. and hot rolling to form a first plate material having a thickness of 2.0 mm or more and 3.6 mm or less, and after completely softening annealing the first plate material, performing a first cold rolling, and After the first cold rolling, intermediate annealing is performed at a temperature of 400°C to 550°C for 5 seconds to 30 seconds, followed by cold rolling at a final cold rolling rate of 30% to 70% to a thickness of 0.20 mm or more. A method for producing an aluminum alloy plate for a cap material, comprising forming a second plate material with a thickness of 0.26 mm or less, and subjecting the second plate material to final annealing at 180° C. or more and 260° C. or less 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 a second cold rolling at a reduction rate of 10% to 40%, and then subjected to the complete softening annealing. The method for manufacturing an aluminum alloy plate for cap material according to claim 2, characterized in that: