JP6611338B2 - Method for producing aluminum alloy plate for thin-walled beverage can excellent in formability and anisotropy - Google Patents

Description

  The present invention relates to a method for producing an aluminum alloy plate for a thin-walled beverage can excellent in formability and anisotropy.

An Al—Mn alloy hard plate such as JIS3004 (AA3004) or JIS3104 alloy is used for a can body of an aluminum can for beverages. The alloy hard plate is required to have strength and corrosion resistance necessary for use as a beverage container, a beautiful appearance, and excellent formability.
The said alloy hard plate is manufactured through processes, such as melting | dissolving, casting, homogenization, hot rolling, cold rolling, like a general aluminum alloy plate. In general, the balance of strength and formability of each part of the can body is tempered from 3/4 hard to special hard. That is, the aluminum alloy plate is recrystallized once in the course of rolling to be in a soft state, and then cold-rolled with a reduction rate of about 50 to 90% to obtain an appropriate strength mainly by work hardening.

When an aluminum alloy sheet is rolled using a recent industrial cold rolling mill, the material temperature becomes high due to heat generated by rolling, so that sufficient ductility can be obtained even with rolling. Therefore, the aluminum alloy sheet is usually used in a tempered condition (H16 to H19) as it is rolled. When sufficient ductility cannot be obtained, for example, when the rolling speed of the aluminum alloy plate is slow, it is conceivable that the aluminum alloy plate is used with H3X refining by performing stabilization annealing.
However, if the mechanical properties of the aluminum alloy rolled plate are anisotropic, the formability when forming the can body is hindered, the symmetry of the can body after forming is reduced, and the material usage yield is reduced. There are problems such as lowering. The anisotropy of the rolled sheet depends on the crystal grain orientation distribution (texture). Therefore, it is considered that the anisotropy of the rolled aluminum alloy sheet can be reduced by taking into account the change in texture due to cold rolling and controlling the texture that occurs during recrystallization before cold rolling.

From the above viewpoint, in order to control the anisotropy of the aluminum alloy rolled sheet, it is technically important how to control recrystallization before cold rolling. From this viewpoint, aluminum for thin-walled beverage cans The manufacturing method of an alloy plate can be classified into the following three types.
(1) Hot rolling → Recrystallization → Final cold rolling In the first method, hot rolling is performed to a relatively thin aluminum alloy sheet of, for example, 3 mm or less, and after hot rolling, it is wound on a coil. This is a method in which recrystallization is performed as it is, or after artificial annealing and recrystallization, and then cold rolling.
(2) Hot rolling → low-pressure cold rolling → recrystallization → final cold rolling The second method is hot rolling to a relatively thin-walled aluminum alloy sheet of, for example, 3 mm or less, and then under a relatively low pressure. For example, as described in Patent Document 1 below, after 6-15% of the aluminum alloy sheet is cold-rolled, it is annealed and recrystallized, and finally the final cold at a reduction rate of about 90%. This is a method of performing rolling.
(3) Hot rolling → cold rolling → recrystallization using a continuous annealing furnace → final cold rolling at a relatively low pressure The third method is to perform first cold rolling after hot rolling of an aluminum alloy sheet. Then, using a continuous annealing furnace, rapid heating to a relatively high temperature, followed by rapid cooling, recrystallization, and finally cold rolling at a relatively low low rate of, for example, about 60% Is the method.

In addition to the manufacturing method described above, when hot rough rolling and hot finish rolling are performed on an aluminum alloy slab, the starting temperature of hot rough rolling is defined, and the reduction amount of each pass with a thickness of 200 mm to 150 mm and 150 mm Re-crystallization is promoted by temperature control at each stage of ~ 15mm, temperature control up to the final pass in hot finish rolling, rising temperature, and rising plate thickness are controlled to formability and paint baking of DI cans during DI processing. A method for producing an aluminum alloy plate with excellent later formability is known (see Patent Document 2).
In addition, the aluminum alloy ingot is cold-rolled at a rolling rate of 80% or more after hot rolling, and when the outlet temperature after cold rolling is 140 to 150 ° C, cooling to 110 ° C is 5 ° C / hour or less. A method for producing an aluminum alloy plate for containers is known in which a speed is selected and cooling is performed at a cooling rate of 30 ° C./hour or less to 110 ° C. when the outlet temperature is 150 to 180 ° C. (see Patent Document 3).

Japanese Patent No. 3644819 Japanese Patent No. 3644818 Japanese Patent No. 3748438

By the way, the demand for lower prices for aluminum cans is severe, and therefore, attempts to reduce the amount of material used as much as possible continue. However, since it becomes difficult to balance formability and anisotropy when the material plate thickness is reduced, there is an increasing demand for a good balance between formability and anisotropy.
For example, to control the anisotropy of an aluminum alloy sheet, it is effective to use a tandem hot finish rolling mill, but a single reverse hot finish rolling mill can obtain sufficient cubic orientation. However, it is difficult to control the anisotropy.

Further, when the method (1) described above is compared with the method (2), the method described in (2) is a process of cold rolling under a relatively low pressure compared to the method described in (1). However, this cold rolling process has the advantage that the development of the cube texture during annealing can be promoted.
The inventors have conducted various studies on the conditions for producing an aluminum alloy sheet for thin-walled beverage cans using a single reverse hot finish rolling mill. As a result, the hot rolling conditions were controlled, and cold rolling and By controlling the intermediate annealing conditions, the inventors have found a production method capable of realizing the control of anisotropy while ensuring the formability, and have reached the present invention.

  This invention is made | formed in order to solve the above-mentioned problem, and it aims at provision of the manufacturing method of the aluminum alloy plate for thin-walled beverage cans which is excellent in a moldability and anisotropy.

The manufacturing method of the aluminum alloy plate for thin-walled beverage cans of the present invention is mass%, Si: 0.35% or less, Fe: 0.35-0.55%, Cu: 0.15-0.48%, Mn : 0.8 to 1.15%, Mg: 0.60 to 1.60%, an ingot obtained by melting and semi-continuously casting an aluminum alloy having the balance consisting of Al and inevitable impurities Is subjected to a homogenization treatment and a soaking process to form a hot rough rolled sheet by hot rough rolling at a delivery-side material temperature of 400 to 460 ° C., and then the first pass first-side temperature is 380 ° C. or lower, and the second pass first-side side. After obtaining a hot-finished rolled sheet having a thickness of 2 to 4 mm by hot finish rolling with a temperature of 340 ° C. or lower and a 3-pass finish side finishing temperature of 240 to 300 ° C., the first reduction is performed at a rolling reduction of 30 to 59%. Cold rolling, then using a continuous annealing device, holding temperature 300-400 ° C., holding The first intermediate annealing is performed for 5 to 30 seconds, the second cold rolling is performed at a rolling reduction of 5 to 20%, and then the batch annealing is performed at a holding temperature of 320 to 380 ° C. and a holding time of 2 to 6 hours. Then, the final cold rolling is performed until the sheet thickness becomes 0.200 to 0.280 mm at a rolling reduction of 70 to 90% to obtain an aluminum alloy sheet having a proof strength of 230 to 320 N / mm ² after baking. The manufacturing method of the aluminum alloy plate for thin-walled beverage cans which is excellent in formability and anisotropy.

In the method for producing an aluminum alloy plate for a thin-walled beverage can according to the present invention, at least one of Cr: 0.05% or less, Zn: 0.25% or less, Ti: 0.10% or less with respect to the composition. An aluminum alloy containing two or more seeds can be used.
In the method for producing an aluminum alloy plate for thin-walled beverage cans according to the present invention, the homogenization treatment is performed at a temperature range of 555 to 605 ° C for 4 to 10 hours, and the soaking is performed at a temperature range of 500 to 555 ° C for 1 hour or more. It is preferable.
In the method for producing an aluminum alloy plate for a thin-walled beverage can according to the present invention, it is preferable that after the cold rolling, final stabilization annealing is performed under conditions of a holding temperature of 120 to 140 ° C. and a holding time of 2 to 4 hours.

The manufacturing method of the aluminum alloy plate for thin-walled beverage cans of the present invention melts an aluminum alloy having a specific range of Si, Fe, Cu, Mn, and Mg, and performs material temperature 400 to 460 on the outlet side by hot rough rolling. After obtaining a rolled sheet at 0 ° C., it is subjected to hot finish rolling for controlling 1 to 3 passes to a specified delivery temperature, and the first cold rolling and continuous annealing, the second cold rolling and batch annealing under specific conditions By performing the final cold rolling to a thickness of 0.200 to 0.280 mm, an aluminum alloy plate for a thin beverage can excellent in both formability and anisotropy can be provided.
Moreover, the aluminum alloy plate for thin-walled beverage cans which is further excellent in formability and anisotropy can be provided by performing the stabilization annealing which controlled holding temperature and holding time after the last cold rolling.

Explanatory drawing which shows the apparatus and process which are used in a hot rolling process, when implementing the manufacturing method which concerns on this invention. The block diagram which shows an example of a continuous annealing apparatus. Process drawing which shows an example of the manufacturing method of DI can. The fragmentary sectional view which shows an example of DI can.

Hereinafter, although each embodiment of the aluminum alloy plate for thin-walled beverage cans according to the present invention will be described, the present invention is not limited to the embodiment described below.
First, the composition of the aluminum alloy plate for thin-walled beverage cans used in this embodiment will be described.
The aluminum alloy plate for thin-walled beverage cans of this embodiment is in mass%, Si: 0.35% or less, Fe: 0.35-0.55%, Cu: 0.15-0.48%, Mn: 0 .80 to 1.15%, Mg: 0.60 to 1.60% or less, and the balance is made of an aluminum alloy having a composition of inevitable impurities and Al. Further, an aluminum alloy containing one or more of Cr: 0.05% or less, Zn: 0.25% or less, Ti: 0.10% or less in the aluminum alloy having the above composition ratio. May be used.
Hereinafter, the reasons for limiting the composition of the aluminum alloy used in this embodiment will be described.
In addition, content of each element described in this specification is mass% unless otherwise specified, and includes an upper limit and a lower limit unless otherwise specified. For example, the notation of 0.35 to 0.55% means 0.35% or more and 0.55% or less.

"Si: 0.35% or less"
Si easily forms a compound with Mg contained at the same time, has a solid solution hardening action, a dispersion hardening action and a precipitation hardening action, and forms a compound with Al, Mn, Fe, etc., and seizes the die during molding. There is an effect to prevent. If the Si content exceeds 0.35 mass%, the workability tends to deteriorate.
"Fe: 0.35-0.55%"
Fe has the effect of preventing crystal fineness and seizure of the die during molding. If the Fe content is less than 0.35% by mass, the desired effect cannot be obtained, and if it exceeds 0.55% by mass, the workability deteriorates.

"Cu: 0.15-0.48%"
Cu easily forms a compound with Mg, and contributes to solid solution hardening, dispersion hardening, and precipitation hardening.
If the Cu content is less than 0.15% by mass, the desired effect cannot be obtained, and if it exceeds 0.48% by mass, the workability deteriorates.
“Mn: 0.8 to 1.15%”
Mn is easy to form a compound with Fe, Si, Al, etc., becomes a crystallization phase and a dispersed phase, exhibits a dispersion hardening action, and has an effect of preventing seizure to a die during molding. If the Mn content is less than 0.8% by mass, desired curing characteristics cannot be obtained, and if it exceeds 1.15% by mass, the workability deteriorates.
“Mg: 0.60 to 1.60%”
Mg has a solid solution strengthening action, enhances work hardening by rolling, and exhibits dispersion hardening and precipitation hardening action by coexisting with Si and Cu. If the Mg content is less than 0.60% by mass, the desired effect cannot be obtained, and if it exceeds 1.60% by mass, the workability deteriorates.

In the aluminum alloy used in the present embodiment, in addition to the main components of Si, Fe, Cu, Mn, and Mg, one or more of the following Cr, Zn, and Ti may be contained.
"Cr: 0.05% or less"
Cr exhibits the effect of preventing seizure on the die during crystal refinement and molding. If the Cr content exceeds 0.05% by mass, the workability deteriorates.

“Zn: 0.25% or less”
Zn has the effect of refining Mg, Si and Cu precipitates. If the Zn content exceeds 0.25% by mass, workability and corrosion resistance are deteriorated.
“Ti: 0.10% or less”
Ti has the effect of improving the workability by refining crystal grains. However, if the Ti content exceeds 0.10% by mass, a coarse compound is formed, and conversely, workability is deteriorated.

<Method for producing aluminum alloy plate for can body>
Next, the manufacturing method of the aluminum alloy plate for thin-walled beverage cans excellent in formability and anisotropy according to this embodiment will be described.
In the method for producing an aluminum alloy plate for thin-walled beverage cans according to the present embodiment, the aluminum alloy having the above composition is melted, and the ingot obtained by casting is subjected to homogenization treatment and soaking, and then hot. Hot rolling by rough rolling and subsequent hot finish rolling is performed, first cold rolling, continuous annealing, second cold rolling and batch annealing are performed, and further, final cold rolling at a reduction rate of 70 to 90% is performed. Thus, an aluminum alloy plate for a thin beverage can having a desired plate thickness is obtained.
Furthermore, in addition to the above-described steps, stabilization annealing can also be performed under conditions of a holding temperature of 120 to 140 ° C. and a holding time of 2 to 4 hours after the final cold rolling.
Hereinafter, the manufacturing method of the aluminum alloy plate for thin-walled beverage cans excellent in formability and anisotropy of this embodiment will be described in the order of steps.

"casting"
After the aluminum alloy having the above composition is melted, an ingot is cast from the molten aluminum alloy according to a conventional method. When the aluminum alloy is melted prior to casting, inclusions such as hydrogen gas and oxide are removed, An ingot is obtained by a continuous casting method.
The solidification rate at this time is usually 5 to 20 ° C./second. The thickness of the cast ingot can be about 500 to 600 mm, for example.
Next, chamfering is performed, and the surface of the ingot is cut by about 1 to 25 mm to produce a chamfered body. The chamfering may be performed after a homogenization process described later.

"Homogenization treatment"
Next, a homogenization process is performed on the manufactured face cut body. The homogenization treatment is generally performed for homogenization of microsegregation generated by solidification of the molten metal, precipitation of supersaturated solid solution elements, transition of a metastable phase formed by solidification to an equilibrium phase, and the like.
In the homogenization treatment, it is important that the homogenization temperature is in the range of 555 to 605 ° C. If the homogenization temperature is less than 555 ° C., the effect of continuous annealing described later cannot be obtained, cracks are likely to occur in the hot rolling process and the first cold rolling process described later, and the ear rate of the final plate material is increased. Further, if the homogenization temperature exceeds 605 ° C, the ingot may be melted.

In the homogenization treatment, it is preferable to heat the face milling body to a homogenization temperature at a heating rate of 100 ° C./hour or less. If the heating rate exceeds 100 ° C./hour, melting may occur partially.
In the homogenization treatment, the time for maintaining the homogenization temperature (homogenization time) is preferably 4 hours or more and 10 hours or less. If the homogenization time is less than 4 hours, the homogenization may not proceed sufficiently. However, if the homogenization time is too long, there is no effect and the production efficiency is lowered. From the above viewpoint, the preferable homogenization time is in the range of 4 to 10 hours. Since the homogenization time is relatively long, this homogenization treatment is usually performed by placing it in a batch type furnace.
In this embodiment, after the homogenization treatment, the face cut body is further cooled to 500 to 555 [deg.] C., and after soaking for a predetermined time, hot rolling is started. The holding time (soaking time) in the temperature range of 500 to 555 ° C. can be performed for 1 hour or more, for example, about 1 to 10 hours.

"Hot rolling"
The hot rolling includes hot rough rolling and subsequent hot finish rolling. In this embodiment, it is preferable to perform hot finish rolling using a single reverse hot finish rolling mill.
In the hot rolling process, as shown in FIG. 1, hot rough rolling is performed to a thickness of about 20 to 16 mm using a hot rough rolling machine 20, and then a hot finishing rolling mill 30 is used to obtain a thickness of 2 to 2 mm. Hot-roll to 4 mm.

The hot roughing mill 20 shown in FIG. 1 includes, for example, upper and lower work rolls 21 and 22, backup rolls 23 and 24, and transport paths 4 and 6 in which a plurality of transport rollers are arranged, and has been transported aluminum. This is an apparatus for rolling an alloy plate 5 to a desired thickness through a gap between work rolls 21 and 22.
In FIG. 1, the hot rough rolling mill 20 is made of a plate material by repeatedly supplying the aluminum alloy plate material 5 to the work rolls 21 and 22 from the conveying paths 4 and 6 on both sides before and after the work rolls 21 and 22 and sequentially rolling them. 5 can be rolled to a required thickness to obtain a plate 7.

  A hot finish rolling mill 30 shown in FIG. 1 is a single reverse hot finish rolling mill, for example, upper and lower work rolls 31 and 32 and backup rolls 33 and 34, and a reel type installed on the entry side of these rolls. And a reel-type delivery take-up device 36 installed on the exit side. The hot finish rolling mill 30 is configured to wind a sheet material that is hot-rolled from the feed winder 35 and passed between the work rolls 31 and 32 by the feed winder 36, and from the feed winder 36. The operation of winding the sheet material hot-rolled by passing between the work rolls 31 and 32 again with the feed winder 35 is repeated as many times as necessary, and the interval between the work rolls 31 and 32 is gradually adjusted for each rolling operation. By doing so, it is an apparatus for hot-finishing and rolling an aluminum alloy plate material to a target plate thickness.

After the soaking process, the slab taken out from the soaking furnace usually starts hot rough rolling immediately, but if the slab temperature does not become less than 500 ° C., the start of hot rough rolling may be delayed. The number of hot rough rolling passes depends on the ingot (slab) thickness, finished thickness, slab width, alloy composition, and the like, but is generally in the range of tens of passes to tens of passes.
In the hot rough rolling, while the rolled material is thick, rolling is usually performed using a one-stand type rough rolling mill (hot rough rolling mill 20 shown in FIG. 1) in which a conveyance table is installed before and after the rolling mill. However, if the plate is thinned, the necessary transfer table length is increased, the slack due to the weight of the plate is increased, and the plate is likely to be cooled.

  Therefore, in order to hold on the transfer table, the plate thickness needs to be more than 10 mm. Therefore, the minimum plate thickness when the plate is sent from the roughing mill to the finishing mill depends on the coil weight and the plate width, but in the case of the weight and width used industrially, it is about 16 mm or more. preferable. Moreover, when the plate | board thickness at the time of sending from a rough mill to a finishing mill is too thick, the increase in the number of rolling passes in a finishing mill will be caused, and productivity will be reduced. Therefore, it is preferable that the upper limit of the sheet thickness when feeding to the finishing mill is 20 mm or less. When the aluminum alloy sheet is thinned from the above upper limit to the lower limit, hot finish rolling is performed with a single mill reverse hot finish rolling mill having the configuration shown in FIG.

Hot finish rolling is performed using a single reverse hot finish rolling mill.
By using a single mill reverse hot finish rolling mill (hot finish rolling mill 30 shown in FIG. 1) having a winding device on both sides of the rolling mill, the hot finish plate thickness can be reduced.
Therefore, since the reduction ratio of the subsequent cold rolling can be reduced, the number of cold rolling passes can be reduced and the productivity can be improved. On the other hand, for example, when a hot finish rolling mill in which the winding device is installed only on one side is used, there is a minimum value for the plate thickness that can be held on the transfer table, so that it can be rolled by hot rolling. The minimum plate thickness will increase. For this reason, the cold rolling reduction after hot rolling increases.

As described above, the reduction in the thickness of the finished sheet of hot rolling contributes to the improvement of productivity by reducing the number of cold rolling passes. Therefore, in this embodiment, it is preferable that the finish plate thickness of hot finish rolling is in the range of 2 to 4 mm. If the finished sheet thickness is less than 2 mm, the reduction ratio of the first cold rolling is insufficient, and a low ear ratio cannot be obtained. If the finished plate thickness exceeds 4 mm, the number of passes of the first cold rolling increases and the productivity decreases.
As conditions for hot finish rolling, the first pass outlet temperature is set to 380 ° C. or lower, the second pass outlet temperature is set to 340 ° C. or lower, and the third pass outlet temperature (finish temperature). Is preferably in the range of 240 to 300 ° C.

If the outlet temperature in the first pass is set to a temperature exceeding 380 ° C., the local strain during rolling becomes a driving force, the recrystallization partially proceeds, the mechanical properties deteriorate, and the random orientation is restored. There is a risk that the number of crystal grains increases and the anisotropy deteriorates.
When the outlet temperature in the second pass is set to a temperature exceeding 340 ° C., the same problem occurs due to the same phenomenon as in the first pass.
With regard to the exit temperature in the third pass, the same problem occurs due to the same phenomenon as in the first pass at a temperature exceeding 300 ° C., and at the temperature below 240 ° C., the nucleus of recrystallized grains with a cubic orientation hardly occurs, and the subsequent batch Even if annealing is performed, sufficient cube orientation does not grow and the anisotropy deteriorates.

"First cold rolling"
In the first cold rolling step, the sheet material cooled after the hot rolling is cold-rolled so as to be in the range of a rolling reduction of 30 to 59%. When the rolling reduction of the first cold rolling exceeds 59%, there is a problem that the number of cold rolling passes increases and productivity is lowered. On the other hand, if the rolling reduction of the first cold rolling is less than 30%, sufficient local strain due to rolling cannot be obtained.
By setting the reduction ratio of the first cold rolling within the range of 30 to 59%, an aluminum alloy plate material excellent in formability and anisotropy can be produced with good productivity.
"Continuous annealing"
Continuous annealing (first intermediate annealing) is a range of heating rate of 10 to 200 ° C./second (10 ° C./second) using the continuous annealing apparatus whose basic configuration is shown in FIG. As mentioned above, it is heated at a range of 200 ° C./second or less, and held at a holding temperature of 300-400 ° C. (300 ° C. or more, 400 ° C. or less) for 5-30 seconds (5 seconds or more, 30 seconds or less) Cooling is performed at a cooling rate of 10 to 200 ° C./second (a range of 10 ° C./second or more and 200 ° C./second or less).
This annealing step brings the aluminum alloy plate material into an appropriate softened state, and it is preferable to set the yield strength after annealing; YS (Yield Strength) within a suitable range.
If the annealing temperature is less than 300 ° C., sufficient softening cannot be obtained, resulting in a high ear rate. When the annealing temperature exceeds 400 ° C. or the holding time exceeds 30 seconds, the softening becomes excessive and the ear rate increases.

FIG. 2 shows a basic configuration example of a continuous annealing device (Continuous Annealing Line: abbreviated CAL). The continuous annealing device 40 of this example draws a long aluminum alloy plate material 42 from a supply roll 41 to provide a shock absorber 43. Is supplied to a long furnace body 44 of about several tens to 100 m through, annealed under the above-mentioned conditions while moving in the furnace body 44, pulled out from the furnace body 44 after annealing, and taken up by a winding roll 47 through a shock absorber 46. It is a device that can be wound around. According to this continuous annealing apparatus 40, since the aluminum alloy plate material 42 passing through the furnace body 44 can be continuously processed alone, the annealing process can be performed under more accurate heating conditions and cooling conditions than the batch type annealing furnace. it can.
And if it is the continuous annealing apparatus 40, even if the width | variety and diameter of the coil of the state which wound the aluminum alloy board | plate material 42 around the supply roll 41 differ, in other words, the width | variety and thickness of the aluminum alloy board | plate material 42, and the length which should be processed Even if the lengths are different, annealing can be performed in the order in which they are to be manufactured.Therefore, the intermediate stock is increased compared to the case of the batch type annealing furnace in which only coils of the same size are brought into the annealing furnace and annealed. Can be suppressed.

"Second cold rolling"
Next, cold rolling is performed on the plate material after the continuous annealing so that the rolling reduction is within a range of 5 to 20%. By setting the reduction ratio of the second cold rolling within the range of 5 to 20%, in addition to the appropriate softened state obtained by the first intermediate annealing, it is possible to introduce appropriate local strain due to the rolling process. In particular, in the final cold rolling step to be described later, a plate material with a low earing rate can be obtained even under a condition where the final cold rolling rate is 70% or more.
If the reduction ratio of the second cold rolling is less than 5%, it is difficult to obtain flatness of the plate property, and the number of rolling passes as a whole process may increase, resulting in a decrease in production efficiency. When the reduction ratio of the second cold rolling exceeds 20%, the ear ratio becomes high.

"Batch annealing"
In the batch annealing step, the plate material after the second cold rolling is held for 2 to 6 hours in a holding temperature range of 320 to 380 ° C. (a range of 320 ° C. or more and 380 ° C. or less) using an annealing furnace. This is done by cooling.
In the batch annealing step, heating is preferably performed at a heating rate of 20 to 150 ° C./hour (range of 20 ° C./hour or more and 150 ° C./hour or less), and a cooling rate of 20 to 200 ° C./hour is 20 ° C./hour. It is preferable to perform the cooling at a time in the range of 200 ° C./hour or more.
If the temperature of batch annealing is less than 320 ° C. or the holding time of batch annealing is less than 2 hours, sufficient recrystallized structure cannot be obtained, and the growth of cube orientation becomes insufficient and anisotropy deteriorates. When the batch annealing temperature exceeds 380 ° C. or the holding time exceeds 6 hours, the recrystallized grains become coarse and the final cold-rolled plate is roughened when it is formed into a cup or DI, and wrinkles are caused accordingly. Due to the occurrence, there is a problem of causing cracks during neck molding.

"Final cold rolling"
Next, the final cold rolling is performed on the plate material after the batch annealing so that the rolling reduction is within a range of 70 to 90%. By setting the reduction ratio of the final cold rolling within the range of 70 to 90%, the required mechanical properties, particularly the proof stress after the coating baking process, are in a suitable range, and the moldability and anisotropy in can molding Can be obtained in a well-balanced manner.
If the rolling reduction of the final cold rolling is less than 70%, the processing rate becomes insufficient, the necessary strength cannot be obtained, and the development of the rolling texture becomes smaller than the cubic orientation obtained by the batch annealing described above, which is anisotropic. Sexual balance gets worse.
If the rolling reduction of cold rolling exceeds 90%, the processing rate becomes excessive, the strength of the plate becomes too high, and the DI formability is impaired. Also, the rolling aggregation compared to the cube orientation obtained by the batch annealing described above. The development of tissue becomes too large and the balance of anisotropy also deteriorates.
By cold rolling, an aluminum alloy plate for a thin beverage can having a thickness of 0.200 to 0.280 mm is obtained. Moreover, it is preferable that this aluminum alloy plate has the yield strength after baking by coating in the range of 230 to 320 N / mm ² .

"Stabilized annealing"
According to the above production method, an aluminum alloy plate for beverage cans excellent in formability and anisotropy can be obtained. In DI molding of the alloy plate, depending on the shape and molding conditions of the bottom of the can, the bottom portion can be removed. May cause problems such as molding defects and bottom wrinkles.
For this reason, it is possible to improve local formability such as the bottom of the can by performing stabilization annealing on the alloy plate under the conditions of a holding temperature of 120 to 140 ° C. and a holding time of 2 hours to 4 hours. Abnormalities can be effectively suppressed.

When the holding temperature is less than 120 ° C., there is a problem in that the above improvement effect is hardly obtained, and when the holding temperature exceeds 140 ° C., the moldability can be improved but the strength is lowered.
If the holding time is less than 2 hours, the above improvement effect is insufficient, which is not preferable. If the holding time is longer than 4 hours, productivity is lowered.
By performing the stabilization annealing treatment under the above-described conditions, there is a feature that DI molding can be performed without causing problems in can molding and problems of productivity reduction.

Below, the outline | summary of the process and DI can which manufacture a DI can using the above-mentioned aluminum alloy plate are demonstrated.
FIG. 3 is a process diagram of a method for manufacturing a DI can, and FIG. 4 is a partial cross-sectional view showing the DI can. In these drawings, reference numeral 10 indicates the DI can.
The DI can 10 is a bottomed cylindrical DI can made of an aluminum alloy. The DI can 10 is an aluminum alloy plate having a thickness of 0.200 mm or more and 0.280 mm or less. It is formed by squeezing and ironing, which is 8% or less. For example, in the case of a 211 cc 350 cc can, the size in the can axis direction, that is, the height is about 122.5 mm, and the outer diameter is 65 mm or more and 67 mm or less. ing. The body portion has a wall thickness of 0.095 mm to 0.110 mm, a tensile strength of 340 MPa to 410 MPa, and a can body weight of 11.6 g or less.

Further, as shown in FIG. 4, the bottom portion 12 of the DI can includes a dome portion 12 a that is recessed toward the inside in the can axis direction of the trunk portion 11, and the outer peripheral edge portion of the dome portion 12 a is a can of the trunk portion 11. It is set as the cyclic | annular convex part 12c which protrudes toward the outer side in an axial direction. A grounding portion 12b is formed in contact with the grounding surface L when the DI can 10 is placed on the grounding surface L so that the top of the annular convex portion 12c in the can axis direction is in an upright posture. ing.
In addition, the DI can 10 uses a paint to print, paint, and heat-dry the outer surface of the body portion 11 including the printed portion of character information and the like, and then coat and heat-dry the inner surface of the DI can 10. Thus, outer surface printing, outer surface coating, and inner surface coating in which a coating film is formed are performed.

This DI can is manufactured by the following processes, for example.
A disk-shaped plate material (blank) W shown in FIG. 3 having a diameter of about 150 mm is formed by punching out the aluminum alloy plate obtained in the above-described process.
Next, the plate material W is drawn into a cup-shaped body W1 by drawing with a cupping press.
Subsequently, the DI processing apparatus performs redrawing and ironing on the cup-shaped body W1 to form a bottomed cylindrical body W2. In this case, the ironing rate is, for example, 60.4%, and the ironing process is performed until the thickness of the thinnest portion of the body portion 11 becomes 0.100 mm.

  The DI processing apparatus used for the redrawing ironing process includes a single redrawing die having a circular through hole for redrawing processing, and a plurality of sheets having circular through holes arranged coaxially with the redrawing die ( For example, three ironing dies (ironing dies) are coaxial with the ironing die, and can be fitted into the through holes of the respective ironing dies, and are movable in the axial direction. A cylindrical punch sleeve and a cylindrical cup holder sleeve fitted to the outside of the punch sleeve are provided.

In the redrawing process by the DI processing apparatus, the cup- shaped body W1 is disposed between the punch sleeve and the redrawing die, the cup holder sleeve and the punch sleeve are advanced, and the cup holder sleeve is cupped on the end face of the redrawing die. The punch sleeve presses the cup- shaped body W1 into the through-hole of the redraw die while pressing the bottom surface of the shaped body W1 to perform the cup pressing operation. As a result, a redrawn cup having a predetermined inner diameter is formed. Subsequently, the redrawn cup is passed through a plurality of ironing dies one after another and gradually ironed, and the side wall of the cup-shaped body is squeezed to extend the side wall to increase the side wall height and wall thickness. To form a bottomed cylindrical body W2.

The bottomed cylindrical body W <b> 2 that has been subjected to the ironing process has its bottom formed in a dome shape, for example, by pushing the punch sleeve further forward and pressing the bottom against the bottom molding die. Thereafter, the molded can is taken out from the DI processing apparatus.
The bottomed cylindrical body W2 is cold-worked and hardened by the side walls being squeezed to increase the strength.

Next, the open end W2a of the bottomed cylindrical body W2 is trimmed.
Since the opening end W2a of the bottomed cylindrical body W2 formed by the DI processing apparatus is uneven and has a concavo-convex shape that undulates in the can axis direction, the opening end W2a of the bottomed cylindrical body W2 is By cutting and trimming, the height of the side wall in the can axis direction is made uniform over the entire circumference.
In this way, a DI can 10 having a circular cross section having a body portion 11 and a bottom portion 12 as shown in FIG. 3 can be formed.

If it is the aluminum alloy plate obtained by the above-mentioned manufacturing method, even when it is subjected to ironing in the above-mentioned DI can manufacturing method, it can be made excellent in neck formability, such as scratches and molding defects. An aluminum can that does not cause problems can be obtained.
Moreover, if it is the aluminum alloy plate obtained by the above-mentioned manufacturing method, it can be made excellent in anisotropy and bottleneck formability as an aluminum alloy plate for a beverage bottle can body, and problems such as scratches and molding defects Can be obtained.

EXAMPLES Hereinafter, although an Example is shown and it demonstrates further in detail about the manufacturing method of the aluminum alloy plate for thin-walled beverage cans which concerns on this invention, this invention is not limited to a following example.
An aluminum alloy having the composition shown in Table 1 was melted, degassed and filtered with a molten metal, and then cast into a slab having a thickness of 600 mm, a width of 1100 mm, and a length of 4.5 m by semi-continuous casting. In addition, all the samples described as 0.01 about Cr, Zn, and Ti are samples containing 0.01 mass% of Cr, Zn, and Ti, respectively.

Next, after chamfering the slab, using a homogenization / soaking furnace, a homogenization treatment with a holding temperature of 565 ° C. and a holding time of 8 hours, and then cooled in the furnace to a holding temperature of 520 ° C., Soaking was performed at the holding temperature for a holding time of 1 hour or longer.
Subsequently, hot rough rolling is performed at a delivery-side material temperature of 430 ° C. using the hot rough rolling mill 20 having the configuration shown in FIG. 1, and then using the single reverse hot finish rolling mill 30 shown in FIG. A plate material having a finished plate thickness of 2 mm was obtained by hot finish rolling.
The exit temperature of the first pass of hot finish rolling is adjusted to 375 ° C. and 385 ° C. as shown in Tables 1 and 2, and the exit temperature of the second pass is adjusted to 330 ° C. and 345 ° C. The delivery temperature in the third pass was adjusted to 240 to 305 ° C. as shown in Tables 3 and 4.

Next, as shown in Table 3 and Table 4, first cold rolling is performed on the plate material after hot rolling at 28 to 62%, and then using a continuous annealing apparatus having a configuration shown in FIG. The first annealing treatment (abbreviated as CAL) was performed under the conditions shown in Table 4, followed by second cold rolling at a rolling reduction of 5 to 25% as shown in Tables 3 and 4.
Next, using a batch annealing furnace, the average heating rate of 20 ° C./hour from room temperature to the holding temperature at the holding temperatures shown in Tables 3 and 4 was adjusted to 2 to 6 hours, and the maximum reached. The sample was cooled under the condition of an average cooling rate of 10 ° C./hour from the temperature to 100 ° C., and batch annealing was performed.
Next, the plate material after batch annealing was subjected to third cold rolling (final cold rolling) at the rolling reductions shown in Tables 3 and 4, and for beverage cans having the plate thicknesses (0.23 mm) shown in Tables 3 and 4 An aluminum alloy plate was obtained.
In addition, about a part of the obtained aluminum alloy plate for beverage cans, further using a batch annealing furnace, at the holding temperatures shown in Tables 3 and 4, the stabilization annealing was performed under the conditions of holding time and 3 hours. went.

The obtained aluminum alloy plate for beverage cans was subjected to a heat treatment equivalent to baking by coating at 210 ° C. for 10 minutes, and the yield strength after baking (ABYS (AB yield strength), 0.2% yield strength) was measured.
In addition, the said physical-property value was measured about the sample extract | collected from the position of three or more each in the width direction and longitudinal direction of a coil.

"Ear rate"
As anisotropy evaluation of the obtained aluminum alloy plate for thin-walled beverage cans, the ear rate in cup molding was measured.
The ear rate was calculated from the height of the side wall of the cup that was deep-drawn from the Eriksen testing machine. The processing conditions were punch diameter: 33 mm (flat head punch), drawing ratio: 1.75, wrinkle holding force: 3 kN. The side wall height of this cup was measured with a digital micrometer, and the ear rate was calculated by the following formula.
(Mountain average height-average valley height) ÷ average valley height x 100 = ear rate (%)
The average height of the 0 ° and 180 ° peaks and the average height of the 45 °, 135 °, 225 °, and 315 ° peaks were determined, and the higher one was defined as the average height of the above equation. In addition, the average valley heights of 90 ° and 270 ° were obtained and used as the average valley height of the above formula.
"Evaluation of Anisotropy"
As an evaluation of anisotropy by the ear ratio, the average value of n = 3 is less than 1.5% “「 ”, 1.5% or more and less than 2.5%“ ◯ ”, 2.5% or more. Less than 5% was designated as “Δ”, and 3.5% or more was designated as “x”. “◎” and “○” were judged to be acceptable levels.

Using the obtained aluminum alloy plate blank material for thin-walled beverage cans, it was molded into a 350 cc beverage can and evaluated for neck formability. After the DI molding, the mouth end of the can was removed by trim, washed and dried, and coated and printed on the inner and outer surfaces of the can, followed by die neck molding and spin flow molding to form a neck shape of a 350 cc beverage can having an inner diameter of approximately 55 mm. In addition, during the DI molding, the thickness of the portion subjected to the neck molding process was thinned to evaluate the generation of wrinkles at the flange tip in the neck molding process. Make 24 cans, visually evaluate the degree of wrinkles at the flange tip, ◎ for those with no wrinkles, ◯ for those with very slight wrinkles, △ with multiple minor wrinkles What was clearly recognized by me was set as x. Moreover, it was set as x also when the crack generate | occur | produced in the neck part.
Table 2 below summarizes the proof stress after baking, the evaluation of anisotropy, and the evaluation of neck formability in each sample.

  Samples Nos. 1 to 18 shown in Table 1 use aluminum alloys having a desirable composition range in the present application, homogenization treatment conditions (temperature, time), soaking conditions (temperature, time), hot rough rolling temperature, hot Rolling (HOT finishing) 1 pass, 2 pass, 3 pass temperature conditions, finishing plate thickness, first cold rolling process rate (%), continuous annealing (CAL) conditions (temperature, time), second cold rolling Although it is a sample in which the processing rate (%), the batch annealing (batch IA) conditions (temperature, time), the third cold rolling processing rate (%), and the final sheet thickness are all in desired ranges, the desired AB proof stress (240 It was found to be an aluminum alloy plate having a good ear rate (anisotropy) and a good neck formability.

The samples of No. 19 shown in Tables 1 and 3 were samples in which the exit temperature of the first pass of hot finish rolling was excessively high, and the samples of No. 20 were excessively increased in the exit temperature of the second pass. Each sample had a problem in neck formability. The sample of No. 21 was a sample in which the outlet temperature in the third pass was excessively raised, causing problems in both anisotropy and neck formability. The sample of No. 22 was a sample in which the outlet temperature in the third pass was made too low and did not cause a problem in neck formability, but the anisotropy deteriorated and the productivity during the first cold rolling was reduced. There was a problem.
The No. 23 sample was a sample in which the first cold rolling reduction ratio was too low, and the No. 24 sample was a first cold rolling reduction ratio that was too high and the third cold rolling reduction ratio was low. All of these samples were problematic in both anisotropy and neck formability.
The sample No. 25 was a sample in which the reduction ratio of the second cold rolling was made too high, the sample No. 26 was a sample in which the temperature of continuous annealing was made too low, and the sample of No. 27 was made high in the temperature of continuous annealing. All of these samples were problematic in both anisotropy and neck formability.
The sample No. 28 is a sample in which the batch annealing temperature is set too low, but both the anisotropy and neck formability are problematic, and the sample No. 29 is a sample in which the batch annealing temperature is set too high. However, there was no problem with anisotropy, but there was a problem with neck formability.

The sample No. 30 is a sample with too much Si content, the sample No. 31 is a sample with too little Fe content, and the sample No. 32 is a sample with too much Fe content. There was a problem with moldability. The No. 31 sample was seized against the die during neck molding.
The sample No. 33 is a sample with too little Cu content, the sample No. 34 is a sample with too much Cu content, and the sample No. 35 is a sample with too little Mn content, but there is a problem in neck formability. As a result, the sample No. 36 has a too high Mn content, but has a problem in anisotropy and neck formability.
The sample of No. 37 is a sample with too little Mg content, but it causes a problem in neck formability, and the sample of No. 38 is a sample with too much Mg content. Both caused problems.
The sample of No. 39 was a sample in which the temperature of the stabilization annealing was increased too much, but when the various alloy components were within the range, the AB yield strength was below the lower limit.

4, 6 ... conveying path, 5, 7 ... plate material, 10 ... DI can, 11 ... trunk, 12 ... bottom part , 12a ... dome part, 12b ... grounding part, 12c ... annular convex part, 13 ... neck part, 14 ... Flange part, 20 ... hot rough rolling mill, 21, 22 ... work roll, 23, 24 ... backup roll, 30 ... hot finish rolling mill, 31, 32 ... work roll, 33, 34 ... backup roll, 35, 36 DESCRIPTION OF REFERENCE SYMBOLS : Delivery winding device , 40 ... Continuous annealing device, 41 ... Supply roll, 42 ... Aluminum alloy plate material, 43, 46 ... Shock absorber, 44 ... Furnace body, 47 ... Winding roll, W ... Plate material (blank), W1 ... cup-like body, W2 ... bottomed tubular body .

Claims (4)

In mass%, Si: 0.35% or less, Fe: 0.35-0.55%, Cu: 0.15-0.48%, Mn: 0.8-1.15%, Mg: 0.60 An ingot obtained by melting an aluminum alloy containing ˜1.60%, the balance consisting of Al and inevitable impurities, and semi-continuously casting is subjected to homogenization treatment and soaking treatment, and the material temperature on the delivery side is set to 400 After forming a hot rough rolled sheet by hot rough rolling at ˜460 ° C., the first pass outlet side temperature is 380 ° C. or lower, the second pass outlet side temperature is 340 ° C. or lower, and the third pass outlet side finish temperature is 240 ° C. After obtaining a hot finish rolled sheet having a thickness of 2 to 4 mm by hot finish rolling to ~ 300 ° C,
The first cold rolling is performed at a rolling reduction of 30 to 59%, and then the first intermediate annealing is performed using a continuous annealing apparatus under the conditions of a holding temperature of 300 to 400 ° C. and a holding time of 5 to 30 seconds, and then a rolling reduction of 5 to 5%. Second cold rolling of 20% is performed, and then batch annealing is performed at a holding temperature of 320 to 380 ° C. and a holding time of 2 to 6 hours, followed by a reduction ratio of 70 to 90% and a plate thickness of 0.200 to 0.280 mm. A method for producing an aluminum alloy plate for a thin-walled beverage can excellent in formability and anisotropy, characterized in that an aluminum alloy plate having a proof stress of 230 to 320 N / mm ² after final baking is performed until final cold rolling .   The formability and the difference according to claim 1, wherein the homogenization treatment is performed at a temperature range of 555 to 605 ° C for 4 to 10 hours, and the soaking is performed at a temperature range of 500 to 555 ° C for 1 hour or more. A method for producing an aluminum alloy plate for thin-walled beverage cans with excellent directivity.   In addition to the above composition, an aluminum alloy containing at least one or more of Cr: 0.05% or less, Zn: 0.25% or less, Ti: 0.10% or less is used. The manufacturing method of the aluminum alloy plate for thin-walled beverage cans excellent in the moldability and anisotropy of Claim 1 or Claim 2 characterized by these.   The formability according to any one of claims 1 to 3, wherein after the final cold rolling, stabilization annealing is performed under conditions of a holding temperature of 120 to 140 ° C and a holding time of 2 to 4 hours. A method for producing an aluminum alloy plate for thin-walled beverage cans having excellent anisotropy.

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