JP6898254B2 - Aluminum alloy plate for can body and its manufacturing method - Google Patents

Description

The present invention relates to an aluminum alloy plate for a can body and a method for producing the same, and more particularly to an aluminum alloy plate capable of exhibiting excellent characteristics during the production of the can body and an effective production method thereof.

Conventionally, aluminum (Al) alloy plates for can bodies have been manufactured by subjecting an Al alloy ingot to homogenization treatment, hot rolling and cold rolling, as is well known. Then, after the Al alloy plate for the can body is subjected to degreasing cleaning, oiling, etc. as necessary, further cup forming, DI forming, trimming, cleaning, drying, painting, baking, necking and flange processing are performed. The can body for beverages and the like is manufactured through the processes such as.

By the way, a can body for beverages and the like is required to have a can body strength that can withstand use, but in the above-mentioned post-painting baking step (hereinafter referred to as a painting baking step). , The strength of the can body will be greatly reduced. Therefore, various proposals have been made for preventing such a decrease in the strength of the can body, and for example, the following techniques have been clarified.

That is, Japanese Patent Application Laid-Open No. 2012-92431 (Patent Document 1) states that an Al alloy cold-rolled plate for bottle cans having a specific alloy composition has a center of gravity diameter of 1 μm represented by the α phase in the plate structure. The number of dispersed particles less than that is reduced, _{and the abundance ratio of the β phase, which is an Al 6} (Fe, Mn) intermetallic compound, and the α phase, which is an Al-Fe-Mn-Si intermetallic compound, is determined by the β phase. Maximum height of X-ray diffraction peak: Maximum height of X-ray diffraction peak of α phase: Ratio to Hα: 0.50 or more in Hβ / Hα, recrystallization of hot rolled plate in plate width direction It has been clarified that the variation in the ear ratio in the plate width direction can be reduced by making the crystal ratio uniform.

Further, in Japanese Patent Application Laid-Open No. 2011-202273 (Patent Document 2), it is an Al alloy cold-rolled plate for bottle cans having a specific alloy composition, and the solid solution amount of Fe and Mn in the plate structure is regulated. By doing so, the number density of relatively large dispersed particles that serve as nucleation sites for recrystallization in the hot-rolled plate is increased, and the central portion in the plate width direction of the hot-rolled plate, especially the central portion of the plate thickness. It is disclosed that the recrystallization is promoted, the recrystallization rate in the plate width direction of the hot-rolled plate is made uniform, and the variation in the ear ratio in the plate width direction is reduced.

On the other hand, in recent years, from the viewpoint of environmental protection, it has become an important issue to recycle recycled lumps of used beverage cans (UBC: Used Beverage Can) in the production of beverage can bodies. Furthermore, in order to reduce the amount of material used, the can body is being made thinner and lighter. However, since Si, Fe, etc. are often mixed in the regenerated ingot of UBC, when the regenerated ingot of UBC is recycled and used, the obtained Al alloy ingot contains Si and Fe in a high concentration. It becomes. In that case, during the heat treatment of the Al alloy ingot, Si forms an intermetallic compound with Mn or Fe, resulting in a decrease in the amount of Mn solid solution. As a result, the heat-resistant softening property of the Al alloy plate is lowered, which causes a problem that the can body strength is further lowered in the coating baking step. In addition, when the initial strength of the Al alloy plate is increased in consideration of the decrease in strength in the painting and baking process, the thinner the plate thickness of the can wall portion due to the thinner and lighter can body, the more the body breaks during DI molding. There is a problem that it is easy to wake up. Therefore, when the recycled lump of UBC is recycled to produce a beverage can body, it is necessary to limit the amount used and add new metal to adjust the Si content.

In addition, Patent Document 1 discloses that the generation of precipitated particles (α phase) of less than 1 μm is suppressed, and Patent Document 2 defines only the solid solution amount of Fe and Mn and heats them. It is disclosed that recrystallization during interrolling is promoted and only the ear ratio is controlled, but it does not achieve both the can body strength and the ear ratio, and the solid solution of Fe, Mn, and Si. We did not pay attention to the amount of dissolved particles and the fine precipitated particles (α phase) during cold rolling.

Japanese Unexamined Patent Publication No. 2012-92431 Japanese Unexamined Patent Publication No. 2011-202273

Here, the present invention has been made in the context of the above circumstances, and the problem to be solved thereof is to provide an Al alloy plate having excellent characteristics for a can body and a method for manufacturing the same. In addition, the strength of the can body is reduced by optimizing the amount of solid dissolved Fe, Mn, and Si in the cold-rolled plate of the Al alloy and the fine precipitated particles (α phase) during cold rolling. An object of the present invention is to provide an Al alloy plate for a can body and a method for producing the same, which can effectively suppress a decrease in the strength of the can body after heat treatment, which affects a problem such as a broken body.

Then, in the present invention, in order to solve the above-mentioned problems, Mn: 0.7 to 1.3%, Mg: 0.8 to 1.5%, Fe: 0. 25-0.6%, Si: 0.25-0.50%, Cu: 0.10-0.30%, Zn: 0.25% or less, Ti: 0.10% or less and B: 0.05 A plate material made of a cold-rolled plate obtained by using a hot-rolled plate containing% or less and the balance of which is an Al alloy made of Al and unavoidable impurities, and is hard in the hot-rolled plate. The amount of dissolved Mn is 0.25% by mass or more, the amount of solid-dissolved Fe is 0.02% by mass or more, the amount of solid-dissolved Si is 0.07% by mass or more, and the conductivity is 30.0 to 40.0% IACS. The tensile strength (TS) in the rolling direction of the cold rolled plate is 280 to 320 MPa, and the tensile strength (ABTS) in the rolling direction after heat treatment at 205 ° C. × 10 minutes is 270 to 310 MPa. At the same time, an Al alloy plate for a can body, characterized in that the difference between the tensile strength (TS) in the rolling direction and the strength (ABYS) in the rolling direction after heat treatment at 205 ° C. for 10 minutes is 50 MPa or less. This is the gist.

Further, in the present invention, based on mass, Mn: 0.7 to 1.3%, Mg: 0.8 to 1.5%, Fe: 0.25 to 0.6%, Si: 0. .25 to 0.50%, Cu: 0.10 to 0.30%, Zn: 0.25% or less, Ti: 0.10% or less and B: 0.05% or less, and the balance is Al. A hot-rolled plate made of an aluminum alloy composed of unavoidable impurities, having a solid-dissolved Mn amount of 0.25% by mass or more, a solid-dissolved Fe amount of 0.02% by mass or more, and 0.07% by mass. An aluminum alloy hot-rolled plate for a can body, which contains the above amount of solid-dissolved Si and has a conductivity of 30.0 to 40.0% IACS, is also a gist thereof. It is a thing.

Further, in the present invention, based on mass, Mn: 0.7 to 1.3%, Mg: 0.8 to 1.5%, Fe: 0.25 to 0.6%, Si: 0. .25 to 0.50%, Cu: 0.10 to 0.30%, Zn: 0.25% or less, Ti: 0.10% or less and B: 0.05% or less, and the balance is Al A plate made of an aluminum alloy composed of unavoidable impurities, the tensile strength (TS) in the rolling direction is 280 to 320 MPa, and the tensile strength (ABTS) in the rolling direction after heat treatment at 205 ° C. × 10 minutes. Is 270 to 310 MPa, and the difference between the tensile strength (TS) in the rolling direction and the strength (ABYS) in the rolling direction after heat treatment at 205 ° C. for 10 minutes is 50 MPa or less. The aluminum alloy plate for rolling is also the gist.

The Al alloy plate for a can body according to the present invention advantageously has a conductivity of 28.4% IACS to 39.8% IACS.

Then, in order to manufacture an Al alloy plate for a can body according to the present invention as described above, (a) based on mass, Mn: 0.7 to 1.3%, Mg: 0.8 to 1.5%, Fe: 0.25 to 0.6%, Si: 0.25 to 0.50%, Cu: 0.10 to 0.30%, Zn: 0.25% or less, Ti: 0.10% or less and B : Hot rolling using the step of preparing an aluminum alloy ingot containing 0.05% or less and the balance being Al and unavoidable impurities as a material, and (b) such an aluminum alloy ingot. The amount of solid-rolled Mn is 0.25 mass% or more, the amount of solid-rolled Fe is 0.02 mass% or more, the amount of solid-rolled Si is 0.07 mass% or more, and the conductivity is 30.0 to 30.0 to The step of obtaining a hot-rolled plate material having 40.0% IACS and (c) cold-rolling the hot-rolled plate material, the tensile strength (TS) in the rolling direction is 280 to 320 MPa, and 205 ° C. × The tensile strength (ABTS) in the rolling direction after the heat treatment for 10 minutes is 270 to 310 MPa, and the tensile strength (TS) in the rolling direction and the strength in the rolling direction (ABYS) after the heat treatment at 205 ° C. × 10 minutes. A manufacturing method including a step of forming a cold-rolled plate material having a difference of 50 MPa or less from the above is advantageously adopted.

Further, in the present invention, in order to advantageously produce the Al alloy plate for a can body as described above, Mn: 0.7 to 1.3% and Mg: 0.8 to 1. 5%, Fe: 0.25 to 0.6%, Si: 0.25 to 0.50%, Cu: 0.10 to 0.30%, Zn: 0.25% or less, Ti: 0.10% The following and B: After chamfering an Al alloy ingot made of an Al alloy containing 0.05% or less and the balance being Al and unavoidable impurities, 550 at a heating rate of 30 to 120 ° C./hour. Homogenization by heating to a homogenization treatment temperature (T) within the range of ~ 620 ° C. and holding at the homogenization treatment temperature (T) for (145-0.24T) hours or longer. After the treatment and then immediately after the completion of the homogenization treatment or at a cooling rate of 10 to 90 ° C./hour, after cooling to a hot rolling start temperature not lower than 500 ° C., the exit temperature: 430- Hot rough rolling is performed so that the temperature is 550 ° C. to form a plate material having a plate thickness of 20 to 40 mm, and then hot finish rolling is performed so that the output side temperature is 300 to 390 ° C. After making a plate material with a thickness of 1.5 to 4.0 mm, cold rolling is performed so that the total workability is 75% or more and the average rolling speed of the stationary portion of the final pass is 700 to 1600 m / min, and the thickness is 0. The gist thereof is a method for manufacturing an Al alloy plate for a can body, which is characterized by having a plate thickness of 2 to 1.0 mm.

In one of the preferred embodiments of the method for producing an Al alloy plate for a can body according to the present invention, the conductivity (S1) of the plate material obtained by the hot finish rolling and the cold rolling can be obtained. The difference (S1-S2) from the conductivity (S2) of the plate material to be rolled is adjusted to be 0.2 to 1.6% IACS.

Further, in another preferred embodiment of the method for producing an aluminum alloy plate for a can body according to the present invention, in the scanning electron micrograph of the homogenized Al alloy ingot, the diameter: 0.1 μm to It is configured so that the area ratio of 1 μm particles is 3.5% or more.

Further, the present invention also covers a beverage can body characterized by being made of the above-mentioned aluminum alloy plate for a can body.

In one of such preferred embodiments of the beverage can body according to the present invention, a predetermined coating and baking treatment is applied to the above-mentioned aluminum alloy plate for the can body.

Therefore, in the case of such an Al alloy plate for a can body having a configuration according to the present invention, the solid dissolution of Fe, Mn, and Si in the hot-rolled plate material of the Al alloy having a specific alloy composition gives it. By optimizing the amount and the fine precipitated particles (α phase) that precipitate during the cold rolling of the hot-rolled sheet metal, high heat-resistant softening characteristics are imparted while ensuring excellent moldability. Further, even after the heat treatment, excellent can body strength can be exhibited, which makes it possible to be advantageously used as a material for a can body.

Further, according to the method for producing an Al alloy plate for a can body according to the present invention, an Al alloy plate for a can body having excellent characteristics such as both moldability and heat treatment strength as described above can be industrially produced. It can be manufactured advantageously.

It is a graph which shows the amount of change of the conductivity when compression processing was performed on two Al alloy materials having different alloy compositions at a temperature of 150 degreeC.

First, the Al alloys that give the Al alloy plate for the can body according to the present invention are Mn: 0.7 to 1.3% (mass standard, the same applies hereinafter), Mg: 0.8 to 1.5%, Fe: 0. 25-0.6%, Si: 0.25-0.50%, Cu: 0.10-0.30%, Zn: 0.25% or less, Ti: 0.10% or less and B: 0.05 It has an alloy composition containing% or less and the balance being Al and unavoidable impurities, and the reasons for limiting these alloy components are as follows.

[Mn: 0.7 to 1.3%]
Mn (manganese) is a basic alloying element in an Al alloy plate according to the present invention, and in addition to increasing the strength, it contributes to the improvement of heat-resistant softening property in a solid solution state. Further, during the manufacturing process, an α-phase compound (Al-Mn-Fe-Si system) is formed with Fe and Si, which are unavoidably contained impurity elements. The particles of the intermetallic compound have extremely high hardness, and have a function of preventing seizure between the material and the molding die at the time of molding and improving the surface texture of the container. If the Mn content is less than 0.7%, those effects cannot be sufficiently exhibited, and if it exceeds 1.3%, the strength becomes too high, which causes a problem. The preferable content of Mn is 0.8 to 1.2%.

[Mg: 0.8 to 1.5%]
Mg (magnesium) is a component that contributes to an increase in the strength of the container by being dissolved in Al. If the Mg content is less than 0.8%, there is a problem that it becomes difficult to obtain the strength required for the final product, and if it exceeds 1.5%, the can body strength becomes too high. , Causes a problem that the moldability is impaired. The preferable content of this Mg is 1.0 to 1.3%.

[Fe: 0.25 to 0.6%]
_{Fe (iron) forms an Al 6} (Mn, Fe) phase compound or an α phase compound (Al-Mn-Fe-Si system) together with Mn at the time of casting, and also forms an Al-Fe-Si system compound. , And the solid lubricating action of these intermetallic compounds is a component that prevents seizure between the material and the molding die during molding. When the Fe content is less than 0.25%, the number of these intermetallic compounds decreases, which causes a problem that the surface texture deteriorates due to adhesion to the die during DI molding. On the other hand, when the Fe content exceeds 0.6%, an Al-Fe-Mn-based intermetallic compound is excessively formed, which becomes a starting point of cracking, and thus is formable. Causes a problem of being impaired. The preferable content of Fe is 0.30 to 0.50%.

[Si: 0.25 to 0.50%]
Si (silicon) forms an α-phase compound (Al-Mn-Fe-Si system) or an Al-Fe-Si system compound having a solid lubricating action together with the above-mentioned Mn and / or Fe, and is a die at the time of molding. It has the effect of preventing adhesion to. This effect is not sufficient when the Si content is less than 0.25%, and when the Si content exceeds 0.50%, the Al-Mn-Fe-Si-based intermetallic compound becomes excessive. When it is formed, it becomes the starting point of cracking, the moldability is impaired, the amount of solid solution Mn is further reduced, and there is a problem that the heat-resistant softening property is lowered. The preferable content of Si is 0.30 to 0.40%.

[Cu: 0.10 to 0.30%]
Cu (copper) forms an Al—Cu—Mg-based intermetallic compound in the coating baking step and precipitates it, and exerts an effect of suppressing or preventing a decrease in strength in the coating baking step. This effect cannot be sufficiently obtained when the Cu content is less than 0.10%, and conversely, when it exceeds 0.30%, the work hardening during molding increases and the moldability deteriorates. Cause problems. The preferable content of this Cu is 0.15 to 0.25%.

[Zn: 0.25% or less]
Zn (zinc) is a component that improves moldability, but when its content is high, in addition to high cost, it causes a problem of forming a coarse intermetallic compound and impairing moldability. become. Therefore, the Zn content is adjusted to be 0.25% or less. The preferable content of Zn is 0.05 to 0.20%.

[Ti: 0.10% or less and B: 0.05% or less]
Ti (titanium) and B (boron) have a function of refining the cast structure and homogenizing the dispersed form and grain structure of the crystals produced during casting. However, if the Ti content exceeds 0.10% or the B content exceeds 0.05%, coarse intermetallic compounds are formed and the moldability is lowered. The preferable contents of Ti and B are 0.03% or less and 0.04% or less, respectively.

[Al + unavoidable impurities: balance]
The Al alloy, which is the material of the Al alloy plate for a can body according to the present invention, is composed of Al (aluminum) and unavoidable impurities, that is, elements other than the above alloy components, in addition to the above alloy components. Is to be done. The content of such unavoidable impurities is preferably as small as possible so as not to deteriorate the plate characteristics, and generally, the content is not more than the upper limit of each element of the Al alloy specified in JIS standards and the like. Will be. The total content of each element that becomes such an unavoidable impurity is generally 0.15% or less, preferably 0.10% or less.

In the case of an Al alloy plate according to the present invention, which is made of an Al alloy having such an alloy composition, the solid solution Mn amount after hot rolling (before cold rolling) is 0.25% by mass or more, and is solid. The amount of dissolved Fe is 0.02% by mass or more, the amount of solid solution Si is 0.07% by mass or more, and the conductivity is 30.0 to 40.0% IACS, which is high. It exhibits heat resistance and softness. When the amount of solid solution of these elements increases, as will be described later, the compound particles composed of Mn, Fe, and Si are finely formed by cold rolling. Further, the solid solution amount of these elements in the hot rolled plate is limited by the content of each element in the Al alloy, and the maximum conductivity realized by the solid solution amount of these elements is 40.0%. It is IACS, and even when the additive element is dissolved to the maximum, the conductivity is 30.0% IACS or more. If the solid solution amount of these elements is less than the lower limit value defined above, the strength will be significantly reduced in the coating baking step.

Further, the Al alloy plate according to the present invention has a characteristic that the tensile strength (TS) in the rolling direction is 280 to 320 MPa as the original plate characteristic. If the tensile strength (TS) is smaller than 280 MPa, there is a problem that the strength of the can body manufactured by using such an Al alloy plate is insufficient, and if it exceeds 320 MPa, DI molding becomes difficult. Problem arises. Further, the Al alloy plate according to the present invention has a characteristic that the tensile strength (ABTS) in the rolling direction after the heat treatment at 205 ° C. × 10 minutes is 270 to 310 MPa. If the tensile strength (ABTS) in the rolling direction after the heat treatment is smaller than 270 MPa, there is a problem that the strength of the can body is insufficient, while if it exceeds 310 MPa, it causes a problem that DI molding becomes difficult. In addition, in the Al alloy plate according to the present invention, the difference (TS-ABYS) between the tensile strength (TS) in the rolling direction and the strength (ABYS) in the rolling direction after heat treatment at 205 ° C. × 10 minutes does not exceed 50 MPa. As described above, it is possible to advantageously balance the moldability of the Al alloy plate and the strength of the can body after heat treatment obtained by using such an Al alloy plate. It was.

By the way, in producing such an Al alloy plate according to the present invention, first, a material giving an Al alloy composition as described above is melted to form an Al alloy molten metal, and then a known casting method, for example, a DC casting method is used. An Al alloy ingot is ingot. Such an Al alloy ingot has an alloy composition having the contents of Mn, Mg, Fe, Si, Cu, Zn, Ti and B specified in the present invention.

Next, the Al alloy ingot is subjected to the same surface milling as before, and then subjected to a specific homogenization treatment in order to obtain the characteristics of the Al alloy plate according to the present invention. That is, in such a homogenization treatment, the surface-ground Al alloy ingot is homogenized at a homogenization treatment temperature (T: ° C.) in the range of 550 to 620 ° C. at a heating rate of 30 to 120 ° C./hour. ), And the homogenization treatment temperature (T) is maintained for (145-0.24 T) hours (Hr) or more. If the heating rate is slower than 30 ° C./hour, the occupancy time of the apparatus becomes long, the manufacturing cost increases, and if it is faster than 120 ° C./hour, a large amount of fine particles are formed. There is a problem that the strength becomes too high and the moldability deteriorates. Further, when the homogenization treatment temperature (T) is lower than 550 ° C., the effect of the homogenization treatment cannot be sufficiently obtained, while when the temperature is 620 ° C. or higher, the material is partially melted and the moldability is significantly lowered. Cause problems. This homogenization treatment eliminates segregation of elements present in the ingot Al alloy to give a uniform structure, and also precipitates a coarse α-phase compound to prevent seizure during molding. It also has features. Then, by setting the holding time of this homogenization treatment to (145-0.24T) hours or more, the cross-sectional structure of the treated Al alloy ingot is subjected to a magnification of 100 times to 20000 using a scanning electron microscope. In the photograph observed at a magnification, the area ratio of the particles having a diameter of 0.1 μm to 1 μm is 3.5% or more, which provides an anti-seizure effect and Mn required for obtaining effective heat-resistant softening property. , Fe and Si are in a state where the solid solution amount can be secured. As the upper limit of the holding time of this homogenization treatment, generally, 30 hours or less, preferably 20 hours or less is preferably adopted from the viewpoint of productivity and the like.

After the above homogenization treatment is completed, the Al alloy ingot is subjected to hot rolling as it is (immediately), and at a cooling rate of 10 to 90 ° C./hour, it does not fall below 500 ° C. ( It is also possible to perform hot rolling after cooling to the hot rolling start temperature (500 ° C. or higher). When the Al alloy ingot is cooled, if the cooling rate is smaller (slower) than 10 ° C./hour, or if it is cooled to a temperature lower than 500 ° C., the cooling step. In the inside, Mn, Fe, and Si are precipitated, and the amount of solid dissolved elements thereof is reduced. As a result, the precipitation of fine particles composed of Mn, Fe, and Si during the subsequent cold rolling is insufficient. As a result, there is a problem that the heat-resistant softness is lowered. Further, when the cooling rate is larger (faster) than 90 ° C./hour, there is a problem that the temperature distribution in the Al alloy ingot becomes non-uniform and the characteristics of the final product become unstable.

In the present invention, hot rolling on an Al alloy ingot is carried out by combining hot rough rolling and hot finish rolling as in the conventional case, and the plate thickness after completion of hot finish rolling is 1.5 to 4. A plate material having a thickness of 0 mm is formed, in which hot rough rolling is performed on the Al alloy ingot which has been homogenized as described above or the Al alloy ingot cooled to a predetermined temperature. The output side temperature (material temperature at the end of hot rough rolling) is set to 430 to 550 ° C., so that a plate material having a plate thickness of 20 to 40 mm is formed. Therefore, when the output side temperature is lower than 430 ° C., there arises a problem that the output side temperature of the hot finish rolling following the hot rough rolling deviates to a lower level, and when the output side temperature exceeds 550 ° C., heat is generated. Coarse recrystallized grains may be generated during interrolling, which may impair moldability. Further, if the thickness of the plate material obtained by this hot rough rolling is thinner than 20 mm, the degree of workability in the subsequent hot finish rolling becomes insufficient, and an effective recrystallization structure cannot be obtained after the hot finish rolling. On the other hand, if the thickness exceeds 40 mm, the degree of workability in hot finish rolling becomes too large, which causes a problem that the anisotropy during DI molding becomes strong.

Further, in the hot finish rolling following the hot rough rolling, a known rolling operation is carried out so that the output side temperature (material temperature at the end of the hot finish rolling) is 300 to 390 ° C. A plate material having a thickness of 1.5 to 4.0 mm is formed. In this hot finish rolling, it is important to adjust the recrystallized structure during cooling after winding the coil of the obtained plate material. When the temperature at the exit side of such hot finish rolling is lower than 300 ° C., the formation of a recrystallized structure becomes insufficient, causing problems such as anisotropy becoming stronger and the strength of the product becoming too high. If the outlet temperature exceeds 390 ° C., the recrystallized grains become coarse and the DI moldability may be impaired. Further, if the plate thickness is thinner than 1.5 mm, the degree of processing in the subsequent cold rolling process is insufficient and the strength is lowered, and conversely, if the plate thickness is too thicker than 4.0 mm, the degree of processing in the cold rolling process is insufficient. The degree of processing becomes high, which causes a problem that the strength becomes too high. Then, by this hot finish rolling, the amounts of the solid solution Mn, Fe, and Si can be secured.

Then, the hot-rolled plate obtained as described above is further subjected to cold rolling, but in the present invention, the total workability of such cold rolling is 75% or more. Moreover, cold rolling is carried out so that the average rolling speed of the stationary portion of the final pass is 700 to 1600 m / min, and an Al alloy plate having a plate thickness of 0.2 to 1.0 mm is formed. The cold rolling is carried out according to the same method as the conventional method, but at that time, when the total workability of the cold rolling is lower than 75%, or the average rolling speed of the stationary portion is 1600 m / If it is larger than the amount, the precipitation of Mn-based compound particles is not sufficient, and the heat-resistant softening property may decrease. Further, when the average rolling speed of the stationary portion is smaller than 700 m / min, there is a problem that the productivity is remarkably lowered. Further, if the thickness of the Al alloy plate obtained there is thinner than 0.2 mm, there is a problem that it becomes difficult to secure the strength of the can body, while if the plate thickness is thicker than 1.0 mm, the weight becomes heavy. It becomes heavy and unsuitable as a beverage can.

Further, in the present invention, the conductivity (S1) of the plate material (hot rolled plate) obtained by the hot finish rolling described above and the plate material (cold rolled plate) obtained by the cold rolling described above In other words, the conductivity of the cold rolled plate is 28.4% IACS to 39.8% so that the difference (S1-S2) from the conductivity (S2) is 0.2 to 1.6% IACS. It is preferable to manufacture the target Al alloy plate so as to be within the range of IACS. When the solid solution Mn is sufficiently present, the compound particles composed of Mn, Fe, and Si are induced by cold working and finely precipitated, so that the heat-resistant softening property can be improved. Incidentally, FIG. 1 shows the results of examining the difference in conductivity between two test pieces made of Al alloys having different Mn contents before and after the compression test at 150 ° C., which simulates cold rolling. However, there, the conductivity of the test piece made of Al alloy containing Mn is increased by cold rolling, whereas the test piece made of Al alloy not added Mn is cold-rolled. Almost no change in conductivity due to the above is observed, which confirms that Mn-based compound particles are precipitated by cold rolling. Basically, in cold rolling, although the conductivity decreases due to processing strain, the conductivity increases due to the precipitation of Mn-based compound particles, so that the amount of decrease in conductivity is 0 as a whole. It is within the range of 2 to 1.6% IACS. If the amount of such decrease in conductivity is smaller than 0.2% IACS, the degree of cold working is insufficient, causing a problem of insufficient strength. On the other hand, if it is larger than 1.6% IACS, The amount of Mn, Fe, and Si-based precipitated particles induced by cold rolling is insufficient, which causes a problem that the heat-resistant softening property is not sufficiently improved.

Then, the Al alloy plate according to the present invention thus obtained is subjected to necessary processing as in the conventional case to form a target can body, and is advantageously used as an Al-based beverage can or the like. Will be. For example, the Al alloy plate according to the present invention is subjected to degreasing cleaning, oiling and the like as necessary, and further, cup forming, DI forming, trimming, cleaning, drying, painting, baking, necking and flange processing are performed. After that, it is made into a beverage can body (can body), and by attaching a can lid (can end) to the body, the target Al-based beverage can can be advantageously manufactured.

Representative examples of the present invention will be shown below to clarify the present invention more concretely, but the present invention is not subject to any restrictions by the description of such examples. Needless to say. Further, in addition to the following examples, various modifications and modifications to the present invention are made based on the knowledge of those skilled in the art, as long as the gist of the present invention is not deviated from the specific description described above. It should be understood that improvements can be made.

In the following Examples and Comparative Examples, the test material produced from the obtained Al alloy plate (original plate: cold-rolled plate) or its intermediate product, the hot-rolled plate, was prepared according to the following method. Measured or evaluated.
(1) Tensile strength (TS) of the original plate in the rolling direction
From each of the Al alloy plates (original plates) obtained in Examples and Comparative Examples, JIS No. 5 test material was prepared in the rolling direction, and rolling was performed by performing a tensile test in accordance with JIS-Z-2241. The tensile strength (TS) in the direction was measured.
(2) Tensile strength (ABTS) and proof stress (ABYS) in the rolling direction after heat treatment at 205 ° C. for 10 minutes.
The test material made of each Al alloy plate (original plate) is subjected to a heat treatment (205 ° C. × 10 minutes) equivalent to the coating baking process, and then a tensile test is carried out in the same manner as in (1) above. The tensile strength (ABTS) and proof stress (ABYS) of the test material after the heat treatment in the rolling direction were measured, respectively.
(3) Measurement of solid solution amount of Si, Fe and Mn (phenol dissolution method)
Small piece samples cut out from the hot-rolled plate after hot-finish rolling obtained in Examples and Comparative Examples were immersed in phenol at 170 ° C. to dissolve the matrix components in the Al alloy, and then benzyl. Alcohol is added to keep the solution in a liquid state, and filtration is performed using a filter having a pore size of 0.1 μm. Then, the precipitate captured on the filter is dissolved in a mixed solution of hydrochloric acid and hydrofluoric acid, and the obtained solution is diluted to perform ICP (Inductively Coupled Plasma) emission spectroscopic analysis. The amount of precipitated Mn, Fe, and Si was determined by The amount of solid solution Mn, Fe, and Si was determined by subtracting the above-mentioned precipitation amount from the content in the ingot.
(4) Conductivity For the plate material after hot finish rolling (hot rolled plate) and the plate material after cold rolling (original plate: cold rolled plate), the conductivity measuring instrument (SIGMATEST2 manufactured by Felster Co., Ltd.), respectively. Using .069), the measurement was performed at a frequency of 960 kHz, and the average value of n = 3 was obtained. When the plate thickness of the test material was less than 1 mm, the test materials (plates) were overlapped so that the total thickness was 1 mm or more and used for measurement.
(5) Evaluation of can-making property The various Al alloy plates (original plates) obtained in Examples and Comparative Examples were cup-molded and DI-molded at an ironing rate of 66% according to a normal can-making method, respectively. After further trimming, the same paint baking as before was carried out to confirm whether or not the can could be made. In addition, the seizure condition of the can wall in the can manufacturing operation was also visually evaluated.

− Example 1-
First, various Al alloys A1 to A10 having the alloy composition shown in Table 1 below were melted according to a conventional method, and then ingots of Al alloys were ingot by a semi-continuous casting method. Next, the obtained Al alloy ingot was face-cut in the same manner as in the conventional case, and then heated and raised to a temperature of 600 ° C. at a heating rate of 40 ° C./hour using an air furnace. It was warmed and subsequently homogenized at a temperature of 600 ° C. for 10 hours. The value of (145-0.24T) hours or more specified in the present invention is 1 hour or more, and the above-mentioned 10-hour homogenization treatment sufficiently satisfies the condition.

Then, after such homogenization treatment, it is subjected to hot rolling as it is (immediately), and first, a reverse rolling mill is operated until the plate thickness becomes 28 mm so that the output side temperature is in the range of 460 to 510 ° C. Using, hot rough rolling similar to the conventional one is carried out, and then hot finish rolling is carried out at 4 stands until the plate thickness becomes 2.2 mm so that the output side temperature becomes a temperature of 300 to 330 ° C. It was carried out by the same method as before using the tandem rolling mill of. Finally, cold rolling was performed for 3 passes to produce an Al alloy plate having a plate thickness of 0.28 mm. The total workability in this cold rolling process was 87.3%. At this time, the average rolling speed of the final pass was set in the range of 900 to 1100 m / min. The temperature at the exit side of the final pass in cold rolling was 145 to 155 ° C.

Test materials (A1 to A10) were prepared for each of the various plate materials made of A1 to A10 Al alloys obtained in each of the above steps, and their performance was evaluated according to the above-mentioned evaluation method. , Shown in Table 2 below. In Table 2 below, the difference (S1-S2) between the conductivity of the hot-rolled plate (S1) and the conductivity of the cold-rolled plate (S2) is shown as the amount of decrease in conductivity in cold rolling. ing.

As is clear from the results in Tables 1 and 2, all the plate materials made of Al alloys A1 to A10 have high tensile strength (TS) in the rolling direction in a state where they have not passed the coating baking step. Not too much, their can-making properties were good. Further, it was confirmed that the Al alloy plates (test materials) of A1 to A10 have high tensile strength (ABTS) in the rolling direction after heat treatment and are also excellent in heat resistance and softness.

-Comparative example 1-
In the various alloy composition compositions shown in Table 3 below, plate materials made of various Al alloys B1 to B13 were produced under the same conditions as in Example 1 above. Then, the characteristics of the test materials (B1 to B13) obtained in the manufacturing process of these Al alloy plates were evaluated in the same manner as described above, and the results are shown in Table 4 below.

As is clear from the results in Tables 3 and 4, the amount of Mn added to the B1 test material was insufficient, so that the amount of solid solution Mn was less than the specified range, and the precipitation during cold rolling was insufficient, resulting in conductivity. Has dropped significantly. As a result, the amount of decrease in strength during the coating baking process was large, and the strength of the can body was insufficient. Further, in the B2 test material, the amount of Mn added was too large, and the strength of the base plate became too high, which caused a problem of breakage during can making. Further, in the B3 test material, the amount of Mg added was insufficient, so that the strength of the base plate and the paint after baking was insufficient. In the B4 test material, since the amount of Mg added was excessive, the strength of the base plate became too high, which caused a problem of breakage during can making. In the B5 test material, since the amount of Fe added was insufficient, the coarse intermetallic compound was insufficient, and surface roughness was caused after can making. In addition, the amount of solid solution Fe was insufficient, and the precipitation during cold rolling was insufficient, so that the strength was greatly reduced during coating baking.

Then, in the B6 test material, since the amount of Fe added was excessive, a coarse intermetallic compound was formed, causing a problem of breakage during can making. Further, in the B7 test material, the amount of Si added was insufficient and the precipitation during cold rolling was insufficient, so that the strength at the time of coating baking was significantly reduced and the can body strength was insufficient. In the B8 test material, the amount of Si added was excessive, and coarse intermetallic compounds were excessively formed, causing a problem of breakage during can making. Further, in the B9 test material, the amount of Cu added was insufficient, and therefore the precipitation strengthening during the coating baking treatment was insufficient, so that the strength was greatly reduced by the coating baking and the can body strength was insufficient. Further, in the test material of B10, since the amount of Cu added is excessive, the strength of the original plate becomes too high, causing a problem of breakage during can making. In addition, in the test materials of B11, B12, and B13, the amounts of Zn, Ti, and B added were excessive, respectively, and as a result, coarse intermetallic compound particles were excessively formed during can manufacturing. The problem of breaking was raised.

− Example 2-
By adopting the alloy component composition (Al alloy: A9) that gives the A9 test material in Example 1, various Al alloy plates of C1 to C13 were produced under various production conditions shown in Table 5 below. The basic manufacturing conditions not shown in Table 5 were the same as in Example 1. Then, test materials (C1 to C13) were prepared by using various Al alloy plates of C1 to C13 obtained in the manufacturing process, and the same evaluations as in the above Examples were performed, and the results were obtained. It is shown in Table 6 below.

As is clear from the results in Tables 5 and 6, the Al alloy plates (test materials) of C1 to C13 each have a high tensile strength (TS) in the rolling direction under the state where the coating and baking are not applied. Not too much, and the values were set appropriately, all of them had good can-making properties.

-Comparative example 2-
By adopting the alloy component composition of Al alloy: A9 in Example 1, various Al alloy plates of D1 to D9 were produced under various production conditions shown in Table 7 below. The manufacturing conditions not shown in Table 7 were the same as in Example 1. Then, the characteristics of the test materials (D1 to D9) made of the Al alloy plate materials (cold rolled plates) of D1 to D9 were evaluated, and the results are shown in Table 8 below.

As is clear from the results in Tables 7 and 8, since the temperature rise rate of the D1 test material during the homogenization treatment is high, fine Mn, Fe, and Si particles are formed during the temperature rise. , The strength increased, causing the problem of breaking during can making. Further, in the D2 test material, since the holding temperature in the homogenization treatment is low, the homogenization effect is not sufficient, the structure becomes non-uniform, and there is a problem that the material breaks during can making. On the other hand, homogenization In the D3 test material in which the holding temperature in the treatment was too high, the structure was eutectic-melted, the structure became non-uniform, and the problem of breakage during can making was caused. Further, in the D4 test material, since the holding time in the homogenization treatment was shorter than (145-0.24T), the equivalent circle diameter showing the solid lubrication effect was 0.1 to 1.0 μm. The formation of Mn, Fe, and Si compound particles was insufficient, and seizure occurred on the surface after can making.

Further, in the D5 test material, since the cooling rate up to the hot rolling (hot rolling) start temperature is small, precipitation proceeds during cooling, and the amount of solid dissolved Mn, Fe, Si decreases, and the material is cooled. During rolling (cold rolling), the precipitation of Mn, Fe, Si-based fine particles became insufficient, resulting in reduced heat-resistant softness, while the D6 test material had a high cooling rate to the hot rolling start temperature. In that case, the temperature inside the ingot became non-uniform, causing variations in the material structure and causing a problem of breakage during can making. In addition, in the D7 test material, since the hot rolling start temperature is low, precipitation progresses in the process of cooling to the hot rolling start temperature, and the amount of solid dissolved Mn, Fe, Si decreases, and Mn, Mn, during cold rolling The precipitation of Fe and Si-based fine particles was insufficient, and the heat-resistant softening property was lowered. As a result, the strength of the can body after coating and baking was insufficient.

Further, the D8 test material has an inherent problem of insufficient strength because the total workability in cold rolling is insufficient. In addition, in the D9 test material, since the rolling speed of the final pass in the cold rolling process is high, the precipitation of Mn, Fe, Si-based fine particles becomes insufficient during cold rolling, and the heat-resistant softening property is lowered. It caused problems.

Claims (5)

Based on mass, Mn: 0.7 to 1.3%, Mg: 0.8 to 1.5%, Fe: 0.25 to 0.6%, Si: 0.25 to 0.50%, Cu : 0.10 to 0.30%, Zn: 0.25% or less, Ti: 0.10% or less and B: 0.05% or less, and the balance is made of an aluminum alloy composed of Al and unavoidable impurities. The hot-rolled plate contains 0.25% by mass or more of solid-dissolved Mn, 0.02% by mass or more of solid-dissolved Fe, and 0.07% by mass or more of solid-dissolved Si. An aluminum alloy hot-rolled plate for a can body, which is characterized by having a conductivity of 30.0 to 40.0% IACS. Based on mass, Mn: 0.7 to 1.3%, Mg: 0.8 to 1.5%, Fe: 0.25 to 0.6%, Si: 0.25 to 0.50%, Cu : 0.10 to 0.30%, Zn: 0.25% or less, Ti: 0.10% or less and B: 0.05% or less, and the balance is made of an aluminum alloy composed of Al and unavoidable impurities. After chamfering the Al alloy ingot to be rolled, the temperature is raised to the homogenization treatment temperature (T) within the range of 550 to 620 ° C. at a temperature rise rate of 30 to 120 ° C. In (T), homogenization treatment is performed by holding for (145-0.24T) hours or more, and then immediately after the completion of such homogenization treatment, or at a cooling rate of 10 to 90 ° C./hour. After cooling to a hot rolling start temperature that does not fall below 500 ° C, hot rough rolling is carried out so that the output side temperature is 430 to 550 ° C to form a plate material having a plate thickness of 20 to 40 mm. Then, hot finish rolling was performed so that the output side temperature was 300 to 390 ° C. to obtain a plate material having a plate thickness of 1.5 to 4.0 mm, and then the total workability was 75% or more and the final pass. Cold rolling is performed so that the average rolling speed of the stationary portion is 700 to 1600 m / min, and the plate thickness is 0.2 to 1.0 mm, so that the tensile strength (TS) in the rolling direction is 280 to 280 to 1. It is 320 MPa, and the tensile strength (ABTS) in the rolling direction after the heat treatment at 205 ° C. × 10 minutes is 270 to 310 MPa, and the tensile strength (TS) in the rolling direction and the tensile strength (TS) after the heat treatment at 205 ° C. × 10 minutes. A method for producing an aluminum alloy plate for a can body, which comprises obtaining an aluminum alloy plate material having a difference from the bearing capacity (ABYS) in the rolling direction of 50 MPa or less. The method for producing an aluminum alloy plate for a can body according to claim 2 , wherein the aluminum alloy plate material has a conductivity of 28.4% IACS to 39.8% IACS. The difference (S1-S2) between the conductivity (S1) of the plate material obtained by the hot finish rolling and the conductivity (S2) of the plate material obtained by the cold rolling is 0.2 to 1.6%. The method for producing an aluminum alloy plate for a can body according to claim 2 or 3, wherein the product is IACS. Any of claims 2 to 4 in which the area ratio of particles having a diameter of 0.1 μm to 1 μm is 3.5% or more in the scanning electron micrograph of the homogenized Al alloy ingot. The method for manufacturing an aluminum alloy plate for a can body according to item 1.

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