JP4791072B2 - Aluminum alloy plate for beverage can body and manufacturing method thereof - Google Patents

Description

  TECHNICAL FIELD The present invention relates to an aluminum alloy plate for beverage can bodies, which is excellent in bottom wrinkling at the time of can bottom molding and excellent in heat-softening resistance after baking, and a method for producing the same.

  As the can body of beverage cans made of aluminum alloy, oil is applied to the aluminum alloy plate for beverage can bodies, cupping and DI molding (Drawing & Ironing) is applied to make the can body, trimming, washing, drying In many cases, two-piece cans are used in which outer surface and inner surface coating baking, necking and flange processing are performed, beverage filling and can lid winding are performed. The aluminum alloy plate for beverage can bodies is manufactured by performing hot rolling after homogenizing an aluminum alloy ingot, performing annealing treatment as necessary, and then performing cold rolling. Usually, in addition to this, finishing treatments such as annealing, degreasing, washing, and lubricating oil application are performed.

  In recent years, due to the need for cost reduction of beverage cans, the thickness of the can body has been reduced (gauge down) and the diameter of the can lid has been reduced. The thinning of the can body facilitates the appearance of a shape defect called “bottom wrinkle”. In addition, to reduce the diameter of the can lid, in order to ensure stackability when cans are stacked, it is necessary to reduce the diameter of the bottom of the can bottom corresponding to this. Conversion also promotes the generation of bottom wrinkles.

With reference to FIG. 2, the mechanism of the occurrence of the above bottom wrinkles will be described.
The thinning of the beverage can body 1 increases the amount of material flowing from the can side wall 2 to the can bottom chime portion 3 to easily cause buckling and constriction. The can bottom chime portion 3 has a bottom wrinkle 3a, ... is generated. Further, it is necessary to reduce the diameter of the bottom of the can bottom, which is the diameter of the can bottom grounding portion 4, by reducing the diameter of the can lid (not shown). The bending phenomenon is likely to occur, and this also promotes the generation of the bottom wrinkles 3a.

  Based on the request to solve the above problems, in the aluminum alloy plate for beverage can bodies excellent in can bottom formability described in Patent Document 1 and the manufacturing method thereof, cold rolling consisting of three passes with controlled outlet temperature is performed. Proposed to do. However, this aluminum alloy plate for beverage can bodies and its manufacturing method reveals the necessary conditions directly to obtain a material having high can body strength and excellent bottom wrinkle properties even though it is a very effective means. However, further study was necessary in terms of realizing highly accurate and highly efficient productivity.

  On the other hand, in Patent Document 2, the elongation rate is 5.5% or more, the work hardening index is 0.06 or more, and the proof stress is 290 N / mm 2 or less. As a reliable means of realizing the quality required for aluminum alloy sheets, examination is still insufficient, and it is necessary to produce materials with high can barrel strength and excellent bottom wrinkle with high accuracy and high efficiency. As a possible, it is not possible to substantially meet the demand for the future reduction in the thickness of the can body and the reduction in the diameter of the can lid.

  In addition, Patent Document 3 relates to the ear rate, and performs hot finish rolling for t seconds {t = 2.8 × 104 × exp (−0.012 × T) (T: hot roughing) after completion of the hot rough rolling. Rolling finish temperature (° C))}, and precisely studying the reduction of the ear ratio by obtaining sufficient recrystallization texture in the reorientation process in the recrystallization process after cooling to room temperature after hot finish rolling However, sufficient studies have not been made in the direction of improving bottom wrinkle resistance and heat softening resistance.

Further, in Patent Document 4, the heating rate and cooling rate of soaking are defined according to the dendrite arm spacing of the ingot structure, and the ear rate is adjusted by adjusting the average crystal grain size and Mn solid solution amount of the Al matrix. A method for producing an aluminum-based hot-rolled sheet in which control is performed is shown.
However, in Patent Document 4, although the temperature rise rate and cooling rate of soaking are studied, the temperature raising / lowering rate is controlled throughout the entire production process to improve bottom wrinkle resistance and heat softening resistance. No consideration has been given.
JP 2001-262261 A JP 2004-3000537 A JP-A-10-195608 JP 2003-342657 A

  It has been clarified that the bottom wrinkle property is improved by lowering the strength of the base plate of the aluminum alloy plate for beverage can bodies and increasing the elongation rate of the base plate. In order to improve the elongation, it is effective to perform an annealing treatment after cold rolling, but there is a problem that the cost increases and the strength of the can body decreases. In the future, it was necessary to develop a high-strength material that had excellent bottom wrinkling properties and excellent heat-resistant softening properties in order to respond to further thinning of the can body and smaller diameter of the can lid.

  In view of the problems in the prior art described above, the present invention provides a surface that can be produced with high production accuracy and productivity, with excellent bottom wrinkle properties and high can barrel strength, and can be further thinned. An object of the present invention is to provide an aluminum alloy plate for beverage can bodies having excellent quality and a method for producing the same.

The present inventors examined the cause of bottom wrinkles in detail, and the higher the work hardenability as the material properties, the more the forming force at the time of redrawing is increased, and the circumferential compressive stress in the vicinity of the bottom is relaxed to suppress bottom wrinkles. I found something to do.
Furthermore, as a result of earnest research, by homogenizing the aluminum alloy containing the predetermined amount shown in the present invention alloy and controlling the hot rolling conditions, the work hardening phenomenon of the material, as well as the Al-Cu after paint baking Since the precipitation hardening phenomenon of the intermetallic compound of the system occurs appropriately, it has been found that both excellent bottom wrinkle properties and heat-resistant softening properties can be achieved, and the present invention has been completed through repeated research.

  That is, the aluminum alloy plate for beverage can bodies of the present invention is Mg: 0.8-1.5%, Mn: 0.5-1.5%, Fe: 0.35-0.5% by weight ratio, Si: 0.20 to 0.35%, Cu: 0.1 to 0.3%, Ti: 0.1% or less, B: 0.05% or less, including the balance Al and inevitable components, The Mn solid solution amount is 0.12 to 0.40% and the Cu solid solution amount is 0.07 to 0.20% by weight ratio, and the change characteristics of the work hardening index (n value) with respect to the strain amount as material characteristics The maximum n value is 0.1 or more, and the electrical conductivity is 34.0 to 39.0% IACS.

  Moreover, in the aluminum alloy plate for beverage can bodies of the present invention described above, the tensile strength (BBTS) in the rolling direction of the base plate is 320 MPa or less, and the proof stress (ABYS) in the rolling direction after heat treatment corresponding to paint baking. Is defined as 250 MPa or more, and BBTS-ABYS, which is the difference between the tensile strength (BBTS) and the yield strength (ABYS) in the rolling direction after heat treatment corresponding to paint baking, is defined as 55 MPa or less.

In addition, the manufacturing method of the aluminum alloy plate for beverage can bodies according to the present invention includes Mg: 0.8 to 1.5%, Mn: 0.5 to 1.5%, and Fe: 0.35 to 0 by mass ratio. 0.5%, Si: 0.20 to 0.35%, Cu: 0.1 to 0.3%, Ti: 0.1% or less, B: 0.05% or less, the remainder being inevitable with Al After producing and chamfering an aluminum alloy ingot containing the components, homogenization treatment is performed in a temperature range of 550 to 620 ° C., and then cooled to room temperature at a cooling rate of 40 ° C./hour or more, and then hot rough rolling is started. Residual time (HR from the end of hot rough rolling to the start of hot finish rolling after reheating at a temperature increase rate of 40 ° C./hour or more to 400 to 500 ° C., which is a temperature range, and performing hot rough rolling. -HT time) within 20 minutes, hot finish rolling is carried out at a delivery temperature of 300 to 350 ° C, The delivery temperature of the final pass rolling and 140 ° C. or higher, after the delivery temperature of the rolling paths other than the final rolling cold rolling was performed with the 110 ° C. or less, 80 ° C. at a cooling rate of 15 to 30 ° C. / Time It is characterized by cooling to .

[Action]
In the aluminum alloy plate for beverage can bodies of the present invention, a predetermined amount of Mn and Cu component elements are dissolved, and the work hardening index (n value) has a maximum n value of 0.1 or more. n value) is defined as a strict index, which keeps the work hardenability during the can molding process above a certain level and has both excellent bottom wrinkle resistance and heat softening resistance. Enables accurate production.

  Further, according to the method for producing an aluminum alloy plate for beverage cans of the present invention, the temperature rise in a specific temperature range between the homogenization treatment and hot rough rolling with the aluminum alloy containing the predetermined amount shown in the present invention alloy. The temperature or cooling rate is managed in conjunction with the hot rough rolling start temperature, and by starting the hot rough rolling in a specific temperature range, the constituent elements of Mn and Cu are appropriately dissolved, resulting in cold Since the work hardening phenomenon of the material during rolling or can molding and the precipitation hardening phenomenon of the Al-Cu intermetallic compound after coating baking occur appropriately, the present invention achieves both excellent bottom wrinkle resistance and heat softening resistance An aluminum alloy plate for beverage can bodies can be manufactured.

The aluminum alloy plate for beverage can bodies of the present invention has a Mn solid solution amount of 0.12 to 0.40%, a Cu solid solution amount of 0.07 to 0.2%, and a material property processing for the strain amount. The maximum value of the n value of the change curve of the curing index (n value) is 0.1 or more, and excellent bottom wrinkle resistance and heat softening resistance are achieved.
Moreover, according to the manufacturing method of the aluminum alloy plate for beverage can bodies of the present invention, the beverage can of the present invention can be controlled by regulating the homogenization treatment and the hot rolling conditions in the ordinary method for manufacturing aluminum alloy plates for beverage can bodies. The aluminum alloy plate for the trunk can be manufactured with high accuracy.

  Below, the reason for limitation of an alloy composition is shown regarding the aluminum alloy plate for drink can bodies of this invention.

[Mg component range: 0.8 to 1.5%]
Mg contributes to improving the strength of the can body by its own solid solution, and is effective in increasing the strength of the bottom portion and improving work hardenability. If it is less than 0.8%, it is difficult to sufficiently obtain the required strength. Further, since sufficient work hardening does not occur during molding, bottom wrinkles are likely to occur. Moreover, since intensity | strength will become high too much when it contains exceeding 1.5%, DI moldability and flange moldability will be impaired. A preferable content is 1.0 to 1.4%.

[Mn component range: 0.5 to 1.5%]
Mn contributes to the improvement of strength and heat softening resistance, and contributes to the formation of a high hardness Al—Mn—Fe—Si intermetallic compound (α phase) having a solid lubricating action. This α phase is an extremely hard intermetallic compound, and has the effect of improving the surface properties of the can body material by solid lubricating action during DI moldability. If it is less than 0.5%, the effect cannot be sufficiently obtained, and Mn cannot be dissolved in a predetermined amount. If it exceeds 1.5%, the strength becomes too high and an excessive amount of Al-Mn-Fe-Si-based coarse intermetallic compound is formed, so that DI moldability and flange moldability are impaired. A preferable content is 0.8 to 1.2%.

[Fe component range: 0.35 to 0.5%]
Fe contributes to the formation of the Al—Mn—Fe—Si intermetallic compound. If it is less than 0.35%, an intermetallic compound necessary for preventing adhesion to the die is not sufficiently formed during DI molding. If it exceeds 0.5%, the material strength becomes too high, and the DI moldability and the flange moldability deteriorate.

[Si component range: 0.20 to 0.35%]
Si transforms the Al—Mn—Fe intermetallic compound and contributes to the formation of an Al—Mn—Fe—Si intermetallic compound having a solid lubricating action. This prevents a problem that the aluminum alloy plate for a beverage can body adheres to a die die due to insufficient lubrication during DI molding. If it is less than 0.2%, the effect is not sufficient, and the surface properties of the can body material are deteriorated to cause a seizure defect. On the other hand, if it exceeds 0.35%, a large number of the intermetallic compounds are formed and recrystallization is inhibited, so that a sufficient recrystallization structure cannot be obtained after hot rolling, and as a result, the material strength is remarkably increased. As a result, DI moldability is reduced. Further, in this case, the n value is lowered and the bottom wrinkle property is also lowered. Moreover, heat-softening property also deteriorates. A preferable component range is 0.25 to 0.32%.

[Cu component range: 0.1 to 0.3%]
Cu is an element that contributes to material strength, and imparts strength improvement by precipitation hardening due to the formation of Al-Cu-Mg-based precipitates in the paint baking process during can making. If it is less than 0.1%, a predetermined amount cannot be dissolved, and sufficient material strength cannot be obtained. If the content exceeds 0.3%, the material strength becomes too high, and the DI moldability deteriorates. Also, softening due to paint baking is too small, and flange formability is reduced. A preferable content is 0.18 to 0.25%.

The addition of Ti and B brings about the effect of grain refinement. Ti is restricted to 0.1% or less, and B is restricted to 0.05% or less. If the Ti content exceeds 0.1%, an Al-Ti-based huge intermetallic compound is generated, and cracks and pinholes are generated during the DI molding process, and the DI moldability and the flange moldability deteriorate. .
On the other hand, if the content of B exceeds 0.05%, a huge Ti-B intermetallic compound is formed, and cracks and pinholes are likely to occur during molding.
As other inevitable impurities, if Zn is 0.3% or less, Cr is 0.3% or less, Zr is 0.1% or less, and V is 0.1% or less, the effect of the present invention is not impaired. Is acceptable.

  Below, the manufacturing method of the aluminum alloy plate for drink can bodies of this invention is demonstrated.

[Homogenization treatment]
An aluminum alloy having the alloy composition of the present invention is produced into an ingot (slab) by, for example, a water-cooled semi-continuous casting method. After this is chamfered, homogenization is performed to remove segregation of solute atoms in the ingot and to make fine precipitates dissolve and facilitate recrystallization.
The homogenization temperature is regulated to 550 to 620 ° C. If it is less than 550 ° C., a sufficient homogenizing effect cannot be obtained, and a recrystallized structure cannot be obtained after hot rolling, so that DI moldability is lowered. If it exceeds 620 ° C., the cast surface is swollen, and further, the eutectic portion is locally melted, so that the surface quality is remarkably lowered. At this time, it goes without saying that the surface quality of the can is impaired, but it also adversely affects DI moldability and flange moldability. If the homogenization time is not maintained for 1 hour or more, the effect is not sufficient, and a certain amount of time must be maintained.

[Temperature increase rate between homogenization and hot rough rolling and cooling rate-starting temperature of hot rough rolling is set in a temperature range of 400 to 500 ° C., and the temperature increase in the temperature range of 400 to 500 ° C. Speed and cooling speed]
After the homogenization treatment, hot rolling is performed. At that time, after cooling to room temperature at a cooling rate of 40 ° C./hour or more, reheating at a temperature increase rate of 40 ° C./hour or more is hot rolling. To start.
The starting temperature of this hot rough rolling is set to a temperature range of 400 to 500 ° C., and the temperature range below the upper limit of the temperature range of 400 to 500 ° C. is the temperature range of 500 ° C. or less, and particularly the lower limit is also included. When it prescribes | regulates, it is a 400-500 degreeC temperature range. The temperature increase rate in the temperature range of 400 to 500 ° C. is regulated to 40 ° C./hour or more. Thereby, solid solution precipitation of the Mn-based intermetallic compound is controlled. In this case, if the heating rate and the cooling rate are less than 40 ° C./hour, the Mn solid solution precipitation amount is reduced and the bottom wrinkle is deteriorated.

[Hot rough rolling]
In performing hot rolling after the homogenization treatment, the hot rough rolling start temperature is regulated to 400 to 500 ° C. When the temperature is less than 400 ° C., the hot rolling end temperature regulated by the present invention cannot be obtained, and the recrystallized structure is not sufficiently formed. Therefore, the material strength becomes higher than necessary, and the DI moldability is lowered. When the temperature exceeds 500 ° C., the Mn-based intermetallic compound is re-dissolved, so the amount of Mn solid solution is increased and the material strength is increased by solid solution hardening, so that DI moldability and flange moldability are deteriorated.

[Residence time from the end of hot rough rolling to the start of hot finish rolling (HR-HT time)]
The stay time from the end of hot rough rolling to the start of hot finish rolling is regulated within 20 minutes. Thereby, solid solution precipitation of Mn is controlled. If it exceeds 20 minutes, a large number of Mn-based intermetallic compounds are formed, and the solid solution amount of Mn decreases.

[Hot finish rolling]
The end temperature range of hot finish rolling is regulated to 300 to 350 ° C.
If it is less than 300 ° C., a recrystallized structure is not sufficiently formed and the material strength becomes abnormally high, so that the DI moldability is lowered. Furthermore, since the strain is stored abnormally, the work curability (n value) is low and the bottom wrinkle property is poor. Furthermore, heat resistance softening property is also bad. If it exceeds 350 ° C., Mn tends to precipitate, so the solid solution amount of Mn decreases.

[Thickness of hot rolled sheet]
The thickness of the hot rolled sheet is preferably 2.5 mm or less. When the plate thickness exceeds 2.5 mm, the cold rolling rate increases, the material strength increases more than necessary, and the DI moldability decreases.

[Cold rolling delivery temperature]
Cold rolling is performed after hot rolling. The delivery temperature of the final cold rolling is 140 ° C. or higher, and the delivery temperature of the other rolling passes is 110 ° C. or less. If the delivery temperature of the final cold rolling is less than 140 ° C., the dislocation density formed by the cold rolling in the middle pass cannot be reduced, and the bottom wrinkling property is lowered. On the other hand, the production temperature of Al-Cu-Mg-based and Al-Cu-Mg-Si-based intermetallic compounds formed during cold rolling is set so that the exit side temperature of rolling in the middle pass is 110 ° C or lower. Is suppressed and the amount of Cu solid solution is increased. When it exceeds 110 ° C., the formation of intermetallic compounds is promoted, the amount of Cu solid solution is reduced, the amount of precipitation hardening after baking is reduced, and the heat softening resistance is lowered. Furthermore, the amount of work hardening during cold rolling increases due to the deposits that are precipitated during cold rolling, and the strength of the base plate increases. Therefore, DI moldability deteriorates. Furthermore, since the work hardening property of the final plate is lowered, the bottom wrinkle property is lowered.

[Outside cooling rate of final cold rolling]
About the cooling rate of the final cold rolling delivery side, the cooling rate up to 80 ° C. during cooling is regulated to 15 to 30 ° C./hour. Thereby, the amount of solid solution of Cu is controlled. If it is less than 15 ° C./hour, a large number of Al—Cu intermetallic compounds are formed and the amount of Cu solid solution is lowered, so that the amount of precipitation hardening after baking is reduced and the heat resistance softening property is lowered. When it exceeds 30 ° C./hour, the recovery of the material structure is suppressed, so that the bottom wrinkle property is lowered.

[Total rolling ratio of cold rolling]
The total rolling rate of cold rolling is desirably 70% or more. If it is less than 70%, the required material strength cannot be secured.

  The reasons for limiting the characteristics of the aluminum alloy plate for beverage can bodies of the present invention are shown below.

  Next, the reasons for limiting the tensile strength of the base plate and the proof strength after baking are described for the aluminum alloy plate for beverage can bodies of the present invention. The tensile strength of the base plate is set to 320 MPa or less. If it exceeds 320 MPa, the molding load becomes too high and the DI moldability is lowered. The yield strength after baking is set to 250 MPa or more. If the pressure is less than 250 MPa, the pressure resistance is insufficient, and when the contents are filled as an aluminum can, the strength that can withstand changes in internal pressure cannot be maintained, and a buckling problem occurs in which the dome shape of the can bottom is reversed.

[Conductivity: 34.0 to 39.0% IACS]
For conductivity, the range is restricted to 34.0-39.0% IACS. Conductivity is a characteristic value that correlates with the amount of solid solution element in the material. When the solute element is dissolved in the material, the effect of improving the strength of the can body by solid solution hardening and high work hardenability (ie n value) ) And heat softening resistance. If it exceeds 39.0% IACS, the amount of the solid solution element is small, so that the effect cannot be sufficiently obtained and the can body strength is not improved. Also, it does not satisfy the bottom wrinkle property and heat softening property. On the other hand, if it is less than 34.0% IACS, the solution is hardened more than necessary and the DI moldability and the flange moldability deteriorate.

[BBTS-ABYS: 55 MPa or less]
As an index of heat resistance softening property, the difference (BBTS-ABYS) between the tensile strength (BBTS) in the rolling direction of the base plate and the proof stress (ABYS) in the rolling direction after coating baking is regulated to 55 MPa or less. If it exceeds 55 MPa, after baking (baking), the amount of softening of the material is more than necessary, so if the base plate tensile strength is specified to be low as in the present invention, sufficient strength after coating baking cannot be ensured. When the pressure strength is insufficient and the contents are filled as an aluminum can, the strength that can withstand changes in internal pressure cannot be maintained.

[Maximum value of n value (work hardening index)]
As shown in FIG. 1, when a change curve of the n value with respect to the strain amount is created in the entire uniform plastic strain, the maximum value of the n value is 0.1 or more. As a result, the work curability during the molding process is increased, so that the molding force is improved, the compressive strain in the circumferential direction of the bottom portion is relaxed, and the bottom wrinkle property is improved. If it is less than 0.1, the effect is not sufficiently obtained, and the bottom wrinkle property is lowered.

[Mn solid solution amount: 0.12 to 0.40%]
Solid solution Mn contributes to improvement of strength by work hardening at the time of cold rolling, improvement of heat softening resistance, and improvement of bottom wrinkle by improvement of work hardening at the time of can molding. If it is less than 0.12%, the effect is not sufficient and the work curability is low, so that bottom wrinkles are likely to occur during redraw molding.
Further, the strength of the can and heat softening resistance are not satisfied. If it exceeds 0.40%, the work hardening amount becomes excessive, the strength increases, and the DI moldability decreases. Moreover, flange moldability falls as a result of improving heat-softening property more than necessary.

[Cu solid solution amount is 0.07 to 0.20%]
The amount of Cu solid solution is effective in reducing the strength reduction after baking. If it is less than 0.07%, the effect is not sufficient, and the softening resistance is lowered. If it exceeds 0.20%, the material strength increases and the DI moldability decreases. Moreover, flange moldability falls as a result of improving heat-softening property more than necessary.

The present invention will be described in detail below based on examples.
The aluminum alloy of the present invention shown in Table 1 is melt cast by a conventional method to produce a slab having a thickness of 500 mm. After chamfering this slab to a thickness of 480 mm and removing the frame structure, it is homogenized at 600 ° C. × 8 hours, cooled to room temperature at a cooling rate of 45 ° C./hour, and then to the starting temperature of hot rough rolling, Reheating is performed at a heating rate of 50 ° C./hour. Next, hot rolling is performed. The hot rough rolling start temperature is 450 ° C., the hot finish rolling end temperature is 330 ° C., the thickness of the hot rolled plate is 2.0 mm, and this is wound around a coil and cooled to room temperature. Next, cold rolling is performed, and the cooling rate on the outlet side of the final cold rolling is applied at 30 ° C./hour to produce an aluminum alloy plate for beverage can bodies having a thickness of 0.3 mm. Cold rolling is 3 passes and the total rolling rate is 85%.

(Comparative Example 1)
An aluminum alloy plate for a beverage can body was produced in the same manner as in Example 1 except that the alloy composition was outside the specified value of the present invention.

  For each aluminum alloy produced in Example 1, (1) mechanical properties, (2) heat softening resistance, (3) conductivity, (4) n value, (5) DI formability, (6) flange formability (7) Bottom wrinkle property, (8) Pressure strength, (9) Mn solid solution amount and Cu solid solution amount were evaluated.

  (1) Mechanical properties were determined by measuring the tensile strength of the base plate in the rolling direction of the manufactured aluminum alloy plate for beverage can bodies and the yield strength after baking. Baking is assumed to be the condition of baking (baking) during can making, and was performed at 205 ° C. for 10 minutes.

  (2) As an index of heat-resistant softening property, a sample having BBTS-ABYS of 55 MPa or less was evaluated as good (◯), and a sample exceeding 55 MPa was determined as defective (x).

  (3) The conductivity was measured by an eddy current method after being kept in a constant temperature room at 20 ° C.

  (4) For the n value, a test piece (JIS No. 5) parallel to the rolling direction was used, the nominal stress was measured at intervals of 0.05% in the entire uniform plastic strain, and the true stress was determined from the result of this tensile test. After calculating the true strain, the n value was obtained by the method of least squares with a calculation range of 1% before and after the nominal strain. Next, using the calculated n value, a change curve of the n value with respect to the true strain is created. It was.

  (5) DI moldability is DI molded into a can body for a general beverage (inner diameter 66 mmΦ, side wall plate thickness 100 μm, side wall tip plate thickness 150 μm). What was able to be made can be judged as good (◯), and those with cracks and fractures were judged as bad (x). Further, even if continuous cans were produced, the case where galling occurred on the surface was marked (Δ).

  (6) Flange formability is as follows: DI molded can body is trimmed and washed, then heated at 205 ° C. for 10 minutes, and then the open end is necked in four stages to obtain an inner diameter (d) of the opening diameter. Was reduced to 57 mm, a 90 ° angle conical jig was pushed in until flange cracking occurred, the diameter (D) of the opening when cracking occurred was measured, and the rate of increase in diameter of the opening (P ) Was calculated from P = ((D−d) / d) × 100 (%). Those with 15% or more were judged as acceptable (◯), and those with 15% or less were judged as unacceptable (x).

  (7) Bottom wrinkle squeezes the cup from the blank, and then the re-drawn can (blank diameter 140 mmΦ, cup diameter 87 mmΦ, redrawn diameter 66 mmΦ) Measurements were made and evaluated at the maximum amplitude. The amplitude of 180 μm or less was judged as good (◯), and 180 μm or more was judged as defective (×).

  (8) The pressure strength was measured by washing the DI-molded can body, heating at 205 ° C. for 10 minutes, applying air pressure to the inside of the can body, and reversing the can bottom dome. A reversal pressure of 650 kPa or higher was judged as good (◯), and a reversal pressure of 650 kPa or lower was judged as defective (x). These survey results are shown in Table 2.

  (9) The solid solution amount of Mn and the solid solution amount of Cu are obtained by dissolving the produced aluminum alloy plate for beverage can bodies with a hot phenol solution, and filtering this sample solution to obtain a residue (compound) and a filtrate (solid solution). ) Were separated by filtration, and after separation by filtration, Mn and Cu in the solid solution dissolved in phenol were quantified using ICP emission analysis (inductively coupled plasma emission analysis).

  Table 1 shows the alloy composition of the examples of the present invention.

  As apparent from Table 2, the aluminum alloy plates (No. 1 to No. 4) for beverage can bodies of Example 1 whose alloy composition is within the specified range of the present invention and whose manufacturing conditions satisfy the present invention are as follows. In addition, both the solid solution amount of Mn and the solid solution amount of Cu are within the specified range of the present invention, the bottom wrinkle is excellent, and other can characteristics required for beverage cans (DI moldability, flange moldability, pressure resistance) Strength) and mechanical properties were good. On the other hand, the aluminum alloy plates for beverage can bodies (No. 5 to No. 14) of Comparative Example 1 whose alloy composition is outside the scope of the present invention have various problems.

  No. In No. 5, since the amount of Mg was large and the tensile strength of the base plate was increased, DI moldability and flange moldability were deteriorated.

  No. No. 6 had a small amount of Mg, so the yield strength after baking was out of the scope of the present invention, resulting in poor pressure strength. Further, the conductivity was low and there was no portion where the maximum value of n exceeded 0.1, and the bottom wrinkle property was lowered.

  No. In No. 7, since the amount of Mn was large, the tensile strength of the base plate was too high and a coarse intermetallic compound was formed, the DI moldability and the flange moldability were lowered.

  No. No. 8 has a small amount of Mn, so that there are few crystallized substances having a solid lubricating action, seizure occurs on the ironing die, the can surface becomes rough and molding becomes poor, and the solid solution amount of Mn is small. Wrinkle decreased. Furthermore, the strength is low and the pressure strength is insufficient.

  No. Since No. 9 had a large amount of Fe, a coarse crystallized product was formed, and DI moldability and flange moldability were lowered.

  No. No. 10 had a small amount of Fe, so that the amount of crystallized material having a solid lubricating action was reduced, the ironing die was baked, the surface of the can was rough, and the molding was defective.

  No. No. 11 has a large amount of Si, so it cannot be recrystallized after hot rolling, and the material strength is abnormally increased. Therefore, DI moldability is bad. Also, the n value is low and the bottom wrinkle is poor. Although the thermal softening property was poor, the base was high in strength, so the pressure strength was not insufficient.

  No. In No. 12, since the amount of Si was small, the amount of crystallized material having a solid lubricating action was reduced, the ironing die was baked, the surface of the can was rough, and molding was poor.

  No. In No. 13, since the amount of Cu was large, the amount of Cu solid solution was increased, and DI moldability and flange moldability were lowered.

  No. No. 14 had a small amount of Cu, so the yield strength after baking was out of the scope of the present invention, resulting in poor pressure strength. Furthermore, since the amount of solid solution of Cu is small, the amount of precipitation hardening after baking is reduced, heat softening resistance is lowered, and there is no portion where the maximum value of n exceeds 0.1, and the conductivity is high. Wrinkles occurred.

  The aluminum alloy A having the composition defined in the present invention shown in Table 1 is melt-cast by a conventional method to form a plate-like ingot (slab) having a thickness of 500 mm and chamfered to a thickness of 480 mm, followed by homogenization treatment and hot rolling. Apply. Next, cold rolling is performed to produce an aluminum alloy plate for beverage can bodies having a thickness of 0.3 mm. The manufacturing conditions are variously changed within the specified values of the present invention.

(Comparative Example 2)
An aluminum alloy plate for beverage can bodies was produced by the same method as in Example 2 except that the production conditions were outside the specified values of the present invention.

  About each aluminum alloy plate for drink can bodies obtained in Example 2 or Comparative Example 2, various characteristics were investigated and the quality was determined by the same method as in Example 1. The production conditions are shown in Table 3, and the survey results are shown in Table 4.

  As is clear from Table 4, each of the aluminum alloy plates for beverage can bodies (No. 15 to No. 21) of Example 2 of the present invention has both the Mn solid solution amount and the Cu solid solution amount within the specified range of the present invention. In addition, the bottom wrinkle was excellent, and other can characteristics (DI moldability, flange moldability, pressure strength) required for beverage cans and mechanical characteristics were good. On the other hand, various troubles occurred in the aluminum alloy plates (No. 22 to No. 35) for beverage can bodies of Comparative Example 2 whose alloy composition was outside the scope of the present invention.

  No. In No. 22, since the homogenization temperature was high, the surface of the ingot was swollen and the eutectic portion was melted, so that the surface quality was remarkably lowered and the DI moldability and the flange moldability deteriorated.

  No. No. 23 has a low homogenization temperature, so that it cannot be recrystallized after hot rolling, and the material strength is abnormally increased. Therefore, DI moldability is bad. Also, the n value is low and the bottom wrinkle is poor. Although the thermal softening property was poor, the base was high in strength, so the pressure strength was not insufficient.

  No. 24 and no. No. 25, since the heating rate and the cooling rate until the start of hot rolling after the homogenization treatment are low, the Mn solid solution amount is outside the scope of the present invention, so the maximum value of n exceeds 0.1. There was no part and the bottom was wrinkled due to high conductivity.

  No. In No. 26, since the hot rough rolling start temperature was high, the Mn solid solution amount was high, the material strength was high, and the heat softening resistance was too high, and the DI moldability and the flange moldability were lowered.

  No. In No. 27, since the start temperature of hot rough rolling was low, the end temperature of hot finish rolling was low, and a recrystallized structure was not sufficiently formed, and DI moldability, bottom wrinkle property, and heat softening property were deteriorated. (Due to the high base, the pressure strength did not become insufficient.)

  No. No. 28 has a long residence time (HR-HT time) from the end of hot rough rolling to the start of hot finish rolling, so the Mn solid solution amount is outside the scope of the present invention, and the maximum value of n is 0.1. The bottom wrinkle was generated because there was no part that exceeded and the conductivity was high. Furthermore, the pressure strength was insufficient.

  No. In No. 29, since the finish temperature of hot finish rolling was high, the Mn solid solution amount decreased, there was no portion where the maximum value of n exceeded 0.1, and the bottom wrinkle property deteriorated because of the high conductivity. Furthermore, the pressure strength was insufficient.

  No. No. 30 has a low finish temperature of hot finish rolling, and thus cannot be made a recrystallized structure after hot rolling, and the material strength is abnormally increased. Therefore, DI moldability is bad. Also, the n value is low and the bottom wrinkle is poor. Although the thermal softening property was poor, the base was high in strength, so the pressure strength was not insufficient.

  No. 31 and no. No. 32, since the exit temperature of the first pass or the second pass of cold rolling is high, the amount of precipitation hardening after baking is reduced, and the amount of Cu solid solution is reduced. The pressure strength decreased. Furthermore, the work hardenability of the material was lowered, there was no portion where the maximum value of n exceeded 0.1, and the conductivity was increased, and the bottom wrinkle property was deteriorated. The base plate strength was high and DI moldability deteriorated.

  No. In No. 33, since the exit side temperature of the final cold rolling was low, the recovery of the material was not sufficient and the n value was low, so that the bottom wrinkle property was lowered.

  No. No. 34 had a high exit side cooling rate in the final cold rolling, so that the material was not sufficiently recovered and the n value was low, so that the bottom wrinkle property was lowered.

  No. No. 35 has a low cooling rate on the exit side of the final cold rolling, so that the amount of Cu solid solution is reduced, the amount of precipitation hardening after baking is reduced, and heat softening resistance and pressure strength are reduced. Furthermore, the work hardenability of the material was lowered, there was no portion where the maximum value of n exceeded 0.1, and the conductivity was increased, and the bottom wrinkle property was deteriorated.

  The present invention relates to an aluminum alloy plate for beverage can bodies used as a can body material for various beverage cans such as carbonated beverages, beer and soft drinks, and aluminum for beverage can bodies excellent in bottom wrinkle resistance and heat softening resistance It can be applied as an alloy plate and a manufacturing method thereof.

It is a change curve of the work hardening index (n value) with respect to the strain amount in the entire uniform plastic strain region. It is a cross-sectional schematic diagram which shows typically the site | part (can bottom chime part) where a bottom wrinkle generate | occur | produces.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Beverage can body, 2 ... Can side wall, 3 ... Can bottom chime part, 4 ... Can bottom grounding part.

Claims (3)

In terms of mass ratio, Mg: 0.8 to 1.5%, Mn: 0.5 to 1.5%, Fe: 0.35 to 0.5%, Si: 0.20 to 0.35%, Cu: 0 0.1 to 0.3%, Ti: 0.1% or less, B: 0.05% or less, including the balance Al and unavoidable components, the Mn solid solution amount by mass ratio is 0.12-0. 40%, Cu solid solution amount is 0.07 to 0.20%, and the maximum n value of the change curve of the work hardening index (n value) with respect to the strain amount is 0.1 or more as a material property and the conductivity is An aluminum alloy plate for beverage can bodies characterized by being 34.0 to 39.0% IACS.   The tensile strength (BBTS) in the rolling direction of the base plate is 320 MPa or less, the yield strength (ABYS) in the rolling direction after heat treatment corresponding to paint baking is 250 MPa or more, and the tensile strength (BBTS) and heat treatment equivalent to coating baking are performed. The aluminum alloy plate for beverage can bodies according to claim 1, wherein BBTS-ABYS, which is a difference from the yield strength (ABYS) in the rolling direction, is 55 MPa or less. By mass ratio: Mg: 0.8 to 1.5%, Mn: 0.5 to 1.5%, Fe: 0.35 to 0.5%, Si: 0.20 to 0.35%, Cu: 0 0.1 to 0.3%, Ti: 0.1% or less, B: 0.05% or less, and after producing and chamfering an aluminum alloy ingot containing the remaining Al and inevitable components, 550 to 620 ° C And then cooled to room temperature at a cooling rate of 40 ° C./hour or higher, and then heated to a starting temperature range of 400 to 500 ° C. at a heating rate of 40 ° C./hour or higher. After reheating and hot rough rolling , the hot finish rolling is set to the exit temperature with the stay time (HR-HT time) from the end of hot rough rolling to the start of hot finish rolling within 20 minutes. 300-350 ° C., then cold rolling, the outlet temperature of the final pass is 140 ° C. or higher, After the delivery temperature of the rolling path other than the last rolling was carried out with 110 ° C. or less, beverage can body for manufacturing method of an aluminum alloy body, characterized by cooling to 80 ° C. at a cooling rate 15 to 30 ° C. / hour.

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