WO2015140833A1

WO2015140833A1 - Aluminum alloy sheet for dr can body and manufacturing method therefor

Info

Publication number: WO2015140833A1
Application number: PCT/JP2014/001635
Authority: WO
Inventors: 聖誠田添; 鈴木　覚
Original assignee: 株式会社Uacj
Priority date: 2014-03-20
Filing date: 2014-03-20
Publication date: 2015-09-24
Also published as: CN106103760A; JP6326485B2; JPWO2015140833A1; CN106103760B

Abstract

Provided is an aluminum alloy for DR can bodies, the alloy having a low earing rate and excellent deep drawing properties even when a batch furnace is used, and a manufacturing method therefor. An aluminum alloy sheet for DR can bodies and a manufacturing method therefor, the aluminum alloy sheet being obtained from an aluminum alloy containing Si: 0.10-0.60 mass% (% below), Fe: 0.10-0.80%, Cu: 0.05-0.25%, Mn: 0.80-1.50%, Mg: 0.80-1.30% and the remainder being obtained from Al and unavoidable impurities and the aluminum alloy sheet being made into a final sheet after passing from an ingot of said aluminum alloy to a hot-rolled sheet and to a process-annealed sheet. In the final sheet, the cube orientation density (CubeO) is 2.00 or more times the random orientation density and the ratio (CubeO/SO) of CubeO to the S orientation density (SO) is 0.40-1.00. After baking, the aluminum alloy sheet has a yield strength of 180-220 MPa and a tensile strength of at least 230 MPa.

Description

Aluminum alloy plate for DR can body and manufacturing method thereof

The present invention relates to an aluminum alloy for a DR can body having excellent deep drawability and a low ear rate, and a method for producing the same.

Aluminum alloys such as A3004 and A3104 in JIS standards are used as body materials for aluminum cans because they have excellent formability and corrosion resistance. There are two types of aluminum can bodies: DR cans manufactured only by deep drawing and DI cans manufactured by deep drawing and ironing. Ear rate is an important property in these aluminum cans. Here, the ear rate will be described. Usually, a cup after deep drawing has a high portion (mountain) and a low portion (valley) at the upper end of the circumferential portion. The difference between the average value of the peak height and the average value of the valley height divided by the average value of the valley height is referred to as the ear rate. When the ear rate is inferior, the productivity is adversely affected, for example, a defective portion is generated at the time of winding with the can lid, or the trimming amount is increased and the yield is lowered.

As the shape of the ear, there are a 0/90 degree ear with a mountain in the 0/90 degree direction with respect to the rolling direction and a 45 degree ear with a mountain in the 45 degree direction with respect to the rolling direction. Each ear has a correlation with the texture, and the Cube orientation: (001) <100> is known to develop 0/90 degree ears, and the β fiber, which is a rolled texture, is known to develop 45 degree ears. ing. When the cold rolling rate increases, the β fiber develops and the 45-degree ear becomes prominent. In order to obtain an excellent ear ratio, a good balance between the Cube orientation and the rolling texture, particularly the S and R orientations: {123} <634> is required.

The DR can body is mainly used for food containers, and demand is expected to increase as the world population increases. The DR can body is currently manufactured by a manufacturing method including an intermediate annealing process. For the intermediate annealing, a box-type annealing furnace (hereinafter referred to as “batch furnace”) and a continuous annealing furnace (hereinafter referred to as “CAL”). Is used. The manufacturing cost of CAL increases, and the capital investment for increasing the production capacity is large. Therefore, in order to reduce the cost, it is necessary to manufacture in a batch furnace, but there is a problem that ear control is more strict and 45-degree ears are more easily developed than CAL.

Also, since the DR can body is formed only by deep drawing, a high degree of deep drawing formability is required. Specifically, high deep drawability and reduction of wrinkles during deep drawing. Deep drawability is evaluated by the limit draw ratio. If the deep drawability is not good, cracks are likely to occur during molding. In addition, when wrinkles occur during deep drawing, the surface quality of the product is significantly reduced. In recent years, the demand for surface quality has become increasingly severe.

Patent Document 1 describes a method for producing an aluminum alloy sheet for packaging having deep drawability and redrawability. Patent Document 2 describes a method for producing a packaging aluminum alloy having high strength and low directionality. Patent Documents 3 to 5 describe aluminum alloy sheets having a low ear ratio that define the hot-rolled sheet, the intermediate annealed sheet, the Cube orientation of the final sheet, and the rolled texture as a technique related to the texture described above. Yes.

In Patent Document 1, the ear is controlled by the homogenization treatment and the cold rolling rate, but it is not possible to obtain a sufficiently low ear rate when intermediate annealing is performed in a batch furnace. Moreover, in the aluminum alloy of patent document 2, since there exists high intensity | strength, there exists a possibility that a wrinkle may generate | occur | produce at the time of deep drawing. Since the demand for surface quality is increasing as described above, it is difficult to apply the aluminum alloy of Patent Document 2 to the DR body material.

On the other hand, although the techniques of Patent Documents 3 to 5 control the metal structure, the use is limited to DI cans. In DI can applications, a high cold rolling rate is achieved without using an intermediate annealing process. Since the super hard material used has a high yield strength, wrinkles are likely to occur during deep drawing, and it is not suitable for DR cans. Moreover, since the hot-rolled sheet structure of Patent Document 5 is a partially recrystallized structure, a partially recrystallized structure cannot be obtained unless the sheet temperature is low. Therefore, the rolling speed, which is one of the manufacturing conditions, must be reduced, and there is a problem that the productivity is lowered and the manufacturing cost is increased.

JP-A 63-145758 Japanese Unexamined Patent Publication No. 1-198454 JP 2001-40461 A JP 2004-244701 A JP 2004-263253 A

Problems to be solved by the invention

As a result of repeating various experiments and studies, the present inventors have successfully developed the S orientation in the matrix in the metal structure before the intermediate annealing step to suppress precipitation at the time of recrystallization. It has been found that an aluminum alloy plate having an excellent ear ratio can be obtained. That is, it is known that the Cube orientation and the S orientation have a rotational relationship of 40 degrees around the <111> axis as the crystal orientation, and the Cube orientation is easy to grow in the S orientation matrix. Therefore, by developing the S orientation, the Cube orientation is easily grown. In addition, the precipitate inhibits recrystallization, suppresses the formation of the Cube orientation, and promotes the formation of the R orientation. Therefore, by sufficiently developing the S orientation and suppressing the number of precipitated particles, an excellent ear ratio was obtained even in the intermediate annealing process using a batch furnace.

Also, the presence or absence of wrinkles during deep drawing is due to the yield strength after baking. When the yield strength after baking is reduced, the generation of wrinkles is suppressed, but since the tensile strength is also reduced, the deep drawability is also inferior. Thus, it has been found that by controlling the cold rolling rate, the proof stress and the tensile strength are appropriately adjusted, thereby suppressing the generation of wrinkles while maintaining a good deep drawability.

The present invention is an aluminum alloy found on the basis of the above knowledge, has a low ear ratio even when a batch furnace is used, and has an excellent deep drawability, an aluminum alloy for DR can body, In addition, an object is to provide a manufacturing method thereof.

The present invention is characterized in that the primary cold rolling rate is appropriately controlled. By increasing the primary cold rolling rate, the S orientation can be developed. However, when the primary cold rolling rate is too high, PSN that is recrystallized from around the crystallized product becomes prominent, and the metal structure becomes a random structure with a reduced Cube orientation density. As a result, it was found that 0/90 degree ears could not be developed, leading to 45 degree ear development. Therefore, by appropriately controlling the primary cold rolling rate, the S orientation is developed into a structure before the intermediate annealing process, and the number of precipitated particles in the structure before the intermediate annealing process and the precipitation during recrystallization are suppressed. It is. Thereby, the growth of the Cube orientation in the annealing process can be promoted. That is, the development of the 0/90 degree ear is promoted, and an excellent ear rate is obtained by a good balance with the secondary cold rolling process. Further, in the secondary cold rolling process, by controlling appropriate proof stress and tensile strength, good deep drawability and aesthetics that can withstand high surface quality can be obtained.

In the present invention, Si: 0.10 to 0.60 mass%, Fe: 0.10 to 0.80 mass%, Cu: 0.05 to 0.25 mass%, Mn: 0.80 to 1.50 mass %, Mg: 0.80 to 1.30 mass%, and is made of an aluminum alloy composed of the balance Al and inevitable impurities, and the final plate is obtained from the aluminum alloy ingot through at least a hot rolled plate and an intermediate annealed plate. An aluminum alloy plate in which the Cube orientation density (CubeO) in the final plate is 2.00 times or more than the random orientation density, and the ratio of CubeO to S orientation density (SO) (CubeO / SO) is DR which is 0.40 to 1.00 and has a proof stress of 180 to 220 MPa and a tensile strength of 230 MPa or more after baking. And an aluminum alloy plate for a body.

In the second aspect of the present invention, in the first aspect, the hot-rolled sheet has a conductivity of 36.0 to 43.0% IACS.

According to a third aspect of the present invention, in the first or second aspect, the Cube orientation density (CubeO) in the intermediate annealing plate is 4.00 or more times the random orientation density, and the CubeO and the R orientation density (RO). And the ratio (CubeO / RO) to 1.00 or more.

The present invention provides the method for producing an aluminum alloy plate for a DR can body according to any one of claims 1 to 3, wherein Si: 0.10 to 0.60 mass%, Fe: 0.00. Contains 10 to 0.80 mass%, Cu: 0.05 to 0.25 mass%, Mn: 0.80 to 1.50 mass%, Mg: 0.80 to 1.30 mass%, and is composed of the balance Al and inevitable impurities. A casting process for casting an aluminum alloy, a homogenization process for homogenizing the ingot, a hot rolling process for hot rolling the homogenized ingot, and a primary cold rolling process for the hot rolled plate A method for producing an aluminum alloy plate for a DR can body, comprising: an intermediate annealing step for annealing the primary cold rolled plate; and a secondary cold rolling step for the intermediate annealed plate.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, in the homogenization step, the ingot is treated at 580 to 620 ° C. for 1 to 12 hours, and the hot rolling step is performed at a start temperature of 450 to 610 ° C. It consists of a hot rough rolling stage at 450 to 550 ° C. and a hot finish rolling stage at an end temperature of 330 to 380 ° C., and the rolling rate of the primary cold rolling process is 85 to 95%. In the intermediate annealing process, The primary cold-rolled sheet is heated to an annealing temperature of 300 to 450 ° C. at an average heating rate of 10 to 100 ° C./hour in a temperature range of 200 ° C. or higher, and then held at the annealing temperature for 1 to 4 hours. The rolling rate in the secondary cold rolling process was 20 to 40%.

In the sixth aspect of the present invention, the method according to the fourth or fifth aspect further includes a final annealing step of annealing the secondary cold rolled sheet after the secondary cold rolling step.

In the present invention, the present invention is as described in claim 6, wherein in the final annealing step, the secondary cold-rolled sheet is annealed at 140 to 190 ° C. with an average temperature increase rate of 10 to 80 ° C./hour in a temperature range of 200 ° C. or higher. The temperature was raised to a temperature and then held at the annealing temperature for 2 to 4 hours.

According to the present invention, an aluminum alloy for a DR can body having a low ear ratio and excellent deep drawability even when a batch furnace is used can be obtained.

1. Aluminum alloy plate for DR can body The aluminum alloy plate for DR can body according to the present invention is made of an aluminum alloy having a predetermined alloy composition, and the final plate has a characteristic of a specific orientation density (CubeO). Later, it has a predetermined strength.

1.1. Composition of aluminum alloy First, the reason for limitation of each component regarding an aluminum alloy composition is demonstrated.

Si: 0.10 to 0.60 mass%
By containing Si, Mg ₂ Si-based particles are precipitated during final annealing and coating baking, thereby contributing to an increase in strength. If the Si content is less than 0.10 mass% (hereinafter referred to as “%”), this effect cannot be obtained, and high-purity metal must be used at the time of casting, which increases raw material costs. On the other hand, if it exceeds 0.60%, the precipitated particles increase, so that recrystallization is hindered in the hot rolling process and the intermediate annealing process. As a result, the formation of the Cube orientation is suppressed, and the ear rate of the final plate is deteriorated. A preferable content of Si is 0.20 to 0.50%.

Fe: 0.10 to 0.80%
The solid solution precipitation state of Mn is controlled by the inclusion of Fe, and the deep drawability is improved by uniformly dispersing the Mn-based crystallized product. If the Fe content is less than 0.10%, this effect cannot be obtained, and high-purity ingots must be used at the time of casting, which increases raw material costs. On the other hand, when it exceeds 0.80%, coarse Al—Fe—Mn—Si based crystallized substances increase, and recrystallization in a high dislocation density region around the crystallized substances called PSN becomes dominant. As a result, the Cube orientation density is lowered, and the ear rate of the final plate is deteriorated. A preferable content of Fe is 0.30 to 0.60%.

Cu: 0.05 to 0.25%
Due to the inclusion of Cu, Al—Cu—Mg and Al—Cu—Mg—Si particles are deposited during final annealing and paint baking, contributing to an increase in strength. If the Cu content is less than 0.05%, this effect cannot be obtained, and if it exceeds 0.25%, the strength becomes too high and the deep drawability deteriorates. A preferable content of Cu is 0.10 to 0.25%.

Mn: 0.80 to 1.50%
Containing Mn contributes to an increase in strength. If the Mn content is less than 0.80%, sufficient strength cannot be obtained. On the other hand, if it exceeds 1.50%, the strength becomes too high and the deep drawability deteriorates. A preferable content of Mn is 0.80 to 1.10%.

Mg: 0.80 to 1.30%
Containing Mg contributes to an increase in strength due to solid solution. Further, the formation of Si and Mg ₂ Si-based particles contributes to an increase in strength during final annealing and paint baking. If the Mg content is less than 0.80%, this effect cannot be obtained. On the other hand, if it exceeds 1.30%, the strength becomes too high and the deep drawability deteriorates. A preferable content of Mg is 0.90 to 1.25%.

The aluminum alloy may contain 0.05% or less of Ti, B, V, etc. as inevitable impurities, and 0.15% or less as a whole.

1.2. Characteristics of orientation density (1)
Next, the feature of the orientation density of the aluminum alloy plate for DR can body according to the present invention will be described. In the present invention, the Cube orientation density (hereinafter referred to as “CubeO”) in the final plate is 2.00 times or more than the random orientation density, and CubeO and S orientation density (hereinafter referred to as “SO”) Ratio (CubeO / SO) is defined as 0.40 to 1.00.

The shape of the ear is determined by CubeO and the balance between CubeO and the rolling texture. When CubeO is less than 2.00 times the random orientation, or CubeO / SO is less than 0.40, the 45-degree ear develops and the ear rate deteriorates. On the other hand, when CubeO / SO exceeds 1.00, a good balance between the 0/90 degree ear and the 45 degree ear cannot be obtained, and the ear rate is similarly deteriorated.

CubeO is preferably 3.00 or more times the random orientation density. The upper limit value of the magnification is not particularly specified, but is naturally determined by the composition and manufacturing conditions of the aluminum alloy, and in the present invention, the upper limit value is set to 7.00 times. CubeO / SO is preferably 0.50 to 1.00.

1.3. Strength Characteristics Next, the strength of the aluminum alloy plate for DR can body according to the present invention will be described. In the present invention, it is defined as having a yield strength of 180 to 220 MPa and a tensile strength of 230 MPa or more after baking. When the yield strength after baking is less than 180 MPa, the strength of the DR can body is insufficient. On the other hand, when the yield strength after baking is over 220 MPa, wrinkles are generated during deep drawing and surface quality is deteriorated. The yield strength after baking is preferably 190 to 210 MPa. Moreover, when the tensile strength after baking is less than 230 MPa, the limit drawing ratio is lowered and the deep drawability is poor. In addition, it is preferable that the tensile strength after baking is 235 MPa or more. Here, the upper limit value of the tensile strength after baking is not particularly specified, but it is naturally determined by the composition and manufacturing conditions of the aluminum alloy, and the upper limit value is set to 255 MPa in the present invention.

1.4. Characteristics of orientation density (2)
Next, the further feature of orientation density of the aluminum alloy plate for DR can body according to the present invention will be described. In the present invention, CubeO in the intermediate annealed plate is 4.00 times or more than the random orientation density, and the ratio (CubeO / RO) between CubeO and R orientation density (hereinafter referred to as “RO”) is 1. Preferably, it is defined as 00 or more.

When CubeO is less than 4 times the random orientation density, or CubeO / RO is less than 1.00, the development of 0/90 degree ears in the intermediate annealed sheet is insufficient, and at the time of secondary cold rolling The 45 degree ear development becomes remarkable and the ear rate is deteriorated.

CubeO is preferably 4.50 or more times the random orientation density. The upper limit value of the magnification is not particularly specified, but is naturally determined by the composition of the aluminum alloy and the manufacturing conditions, and the upper limit value is set to 10 times in the present invention. CubeO / RO is preferably 1.00 or more. Although the upper limit value of CubeO / RO is not particularly defined, it is naturally determined by the composition and manufacturing conditions of the aluminum alloy, and in the present invention, the upper limit value is set to 5.00.

2. Manufacturing method of aluminum alloy plate for DR can body The aluminum alloy plate for DR can body according to the present invention includes a casting step of casting the aluminum alloy having the above-mentioned predetermined composition; a homogenization treatment step of homogenizing the ingot; A hot rolling step for hot rolling the homogenized ingot; a primary cold rolling step for the hot rolled plate; an intermediate annealing step for annealing the primary cold rolled plate at 300 to 450 ° C; and an intermediate annealed plate A secondary cold rolling step.

2-1. Casting process An aluminum alloy having the above alloy composition is cast by a semi-continuous casting method to produce an ingot.

2-2. Homogenization treatment step In the homogenization treatment step, the ingot cast in the casting step is preferably subjected to heat treatment at a temperature of 580 to 620 ° C. for 1 to 12 hours. When the treatment temperature is less than 580 ° C. and the treatment time is less than 1 hour, the homogenization effect is insufficient. In addition, since the number of precipitated particles during the hot rolling process increases, recrystallization after the hot rolling process is hindered. As a result, a rolled structure remains in the hot-rolled sheet, and CubeO also decreases in the recrystallized grains. Since CubeO of this hot-rolled sheet becomes one of the nuclei of Cube-oriented grains during intermediate annealing, it is important not to lower it. On the other hand, when the treatment temperature exceeds 620 ° C., oxidation or blistering occurs on the ingot surface, leading to deterioration of the surface quality. In addition, even if processing time exceeds 12 hours, the further improvement of an effect is not acquired and productivity deteriorates. The temperature of the homogenization treatment step is more preferably 580 to 610 ° C., and the treatment time is further preferably 1 to 4 hours.

2-3. Hot rolling process After the homogenization process, the ingot is subjected to a hot rolling process. The hot rolling process includes a hot rough rolling stage and a hot finish rolling stage. In the hot rough rolling stage, it is preferable that the start temperature is 450 to 610 ° C. and the end temperature is 450 to 550 ° C. When the starting temperature is less than 450 ° C., precipitation of intermetallic compounds occurs and the temperature of the rolled sheet decreases. As a result, the rolled structure remains in the structure after the hot finish rolling, and the 45-degree ears of the final plate are developed. When the starting temperature exceeds 610 ° C., the surface of the rolled sheet is oxidized, and a defect occurs on the surface of the rolled sheet during rolling, resulting in a deterioration in quality. Further, when the end temperature is less than 450 ° C., it is necessary to suppress the deformation resistance by reducing the amount of reduction per pass, and thus the productivity is lowered. On the other hand, when the end temperature exceeds 550 ° C., seizure occurs on the surface of the rolled sheet, and the surface quality deteriorates. The rolling time in the hot rough rolling stage and the hot finish rolling stage is not particularly limited, but is preferably within 20 minutes. It is more preferable that the start temperature of the hot rough rolling step is 470 to 580 ° C. and the end temperature is 450 to 530 ° C.

After the hot rough rolling stage, the rolled plate is subjected to the hot finish rolling stage. In the hot finish rolling stage, the end temperature is preferably set to 330 to 380 ° C. When the end temperature is less than 330 ° C., the driving force for recrystallization is insufficient. As a result, the rolling texture remains on the rolled plate, and the 45 ° ears of the final plate develop and the ear rate deteriorates. Moreover, since it is necessary to suppress a rolling speed, productivity also falls. When the end temperature exceeds 380 ° C., seizure occurs on the surface of the rolled sheet, and the surface quality deteriorates. It is more preferable that the end temperature of the hot finish rolling step is 330 to 370 ° C.

The electrical conductivity of the hot rolled sheet after the hot rolling step is preferably 36.0 to 43.0% IACS. When the electrical conductivity is less than 36.0% IACS, the solution is in a highly solid state, the deep drawability is lowered, and cracking occurs during can making. On the other hand, when the electrical conductivity exceeds 43.0% IACS, precipitates in the hot-rolled sheet increase and the R orientation is preferentially formed during intermediate annealing, so the 45-degree ear development of the final sheet is remarkable. become. The electrical conductivity of the hot rolled sheet is more preferably 36.0 to 42.0% IACS.

The total rolling rate in the entire hot rolling process is not particularly specified, but is preferably 80 to 95%. If it is less than 80%, the S orientation density in the hot-rolled sheet decreases, the 0/90 degree ear during self-annealing becomes weak, and if it exceeds 95%, the recrystallization driving force becomes too high and the ear becomes no-ear, This leads to a decrease in Cube orientation density during intermediate annealing. The total rolling rate in the entire hot rolling process is more preferably 85 to 93%.

2-4. Primary cold rolling process After the hot rolling process, the hot rolled sheet is subjected to the primary cold rolling process. The rolling rate in the primary cold rolling process is preferably 85 to 95%. When the rolling rate is less than 85%, the development of the S orientation, which is the nucleation site of the Cube orientation, is insufficient, and when the rolling rate exceeds 95%, PSN which is the nucleation around the crystallized material is remarkable. Thus, 45 degree ears are developed by secondary cold rolling, which leads to deterioration of the ear rate. The rolling rate in the primary cold rolling process is more preferably 87 to 93%.

2-5. Intermediate annealing step After the primary cold rolling, the cold rolled sheet is subjected to an intermediate annealing step. In the intermediate annealing step, the primary cold-rolled sheet is first heated to an annealing temperature of 300 to 450 ° C. at an average heating rate of 10 to 100 ° C./hour in a temperature range of 200 ° C. or higher, and then at this annealing temperature. It is preferable to hold for 1 to 4 hours. By such an intermediate annealing step, an intermediate annealing plate in which CubeO is 4 times or more with respect to the random orientation and CubeO / RO is 1 or more is obtained.

When the average rate of temperature increase in the temperature range of 200 ° C. or higher is less than 10 ° C./hour, competition between recrystallization and precipitation becomes remarkable, and the formation of the R orientation is rapidly promoted. On the other hand, when the temperature exceeds 100 ° C./hour, a temperature gradient is generated between the inner winding and the outer winding of the coil to cause a difference in thermal expansion, and the overlapping plates are rubbed with each other to deteriorate the surface quality. The reason why the temperature range is limited to 200 ° C. or more is that recrystallization and precipitation compete. The average rate of temperature increase in the temperature range of 200 ° C. or higher is more preferably 15 to 80 ° C./hour.

When the annealing temperature is less than 300 ° C. and the annealing time is less than 1 hour, a complete recrystallized structure cannot be obtained. On the other hand, when the annealing temperature exceeds 450 ° C., the cold rolling oil is baked on the surface of the intermediate annealing plate and the surface quality is deteriorated. When the annealing time exceeds 4 hours, productivity deteriorates. The annealing temperature is more preferably 330 to 400 ° C., and the annealing time is further preferably 2 to 4 hours.

2-6. Secondary cold rolling step The intermediate annealed plate after the intermediate annealing step is subjected to the secondary cold rolling step. The rolling rate in the secondary cold rolling process is preferably 20 to 40%. When the rolling rate is less than 20%, the strength is insufficient. As a result, the strength of the can cannot be obtained, and cracks occur during deep drawing. When the rolling rate exceeds 40%, the yield strength becomes too high, and the ratio between the tensile strength and the yield strength becomes small. As a result, cracks and wrinkles occur during deep drawing. Further, when the rolling rate exceeds 40%, the rolling texture develops, so that the 45 degree ear becomes stronger.

2-7. Final annealing step After the secondary cold rolling, a final annealing step of annealing the secondary cold rolled sheet may be further provided. Thereby, material strength and ductility can be adjusted, and it becomes possible to aim at the further improvement of a moldability. In the final annealing step, the temperature is raised to an annealing temperature of 140 to 190 ° C. at an average temperature increase rate of 10 to 80 ° C./hour, and then held at the annealing temperature for 2 to 4 hours.

When the average heating rate is less than 10 ° C./hour, the productivity is deteriorated. On the other hand, when it exceeds 80 ° C./hour, the amount of heat input becomes insufficient and the effect of annealing cannot be obtained sufficiently, and only the manufacturing cost increases. Further, when the annealing temperature is less than 140 ° C. and the annealing time is less than 2 hours, the effect of annealing becomes insufficient. When the annealing temperature exceeds 190 ° C., the softening proceeds too much and the material strength decreases. When the annealing time exceeds 4 hours, productivity deteriorates. The annealing temperature is more preferably 160 to 180 ° C., and the annealing time is further preferably 2 to 3 hours.

Examples of the present invention will be described based on the present invention examples and comparative examples described below. These examples show one embodiment of the present invention, and the present invention is not limited thereto.

An ingot was produced by DC casting using an aluminum alloy having the composition of A to U shown in Table 1 according to a conventional method. The ingot was homogenized, hot rolled, primary cold rolled, intermediate annealed, secondary cold rolled, and final annealed under the conditions shown in Table 2 to produce a final product having a thickness of 0.22 mm.

Evaluation was made on hot-rolled sheets, intermediate-annealed sheets, and final sheets. First, about a hot-rolled board, electrical conductivity measurement and structure | tissue observation were performed. The conductivity was measured using an eddy current conductivity measuring device and using copper as a reference sample. The structure was observed by polishing the plate cross section (L-ST surface) using the Barker method. In the structure observation, the case where it was a complete recrystallized structure was evaluated as ◯, and the case where the rolled structure remained was evaluated as x.

Next, the intermediate annealed plate was subjected to structure observation and texture evaluation. For structure observation, the plate cross section (L-ST plane) was evaluated in the same manner as the hot-rolled plate. The texture evaluation was performed by the SEM-EBSD method on the plate surface using OIM manufactured by TSL. CubeO and RO were evaluated without considering the tilt angle.

For the final plate, a quarter portion from the surface in the thickness direction was evaluated using an X-ray diffractometer. Also here, CubeO and SO were evaluated without considering the tilt angle as in the case of the intermediate annealing plate.

The final plate was further evaluated for strength, ear coverage, surface quality, and deep drawability. About intensity | strength, it implemented in the rolling direction and the parallel direction using the JIS5 test piece, and measured the yield strength and tensile strength after baking. The baking conditions were 205 ° C. × 10 minutes. For proof stress, pass 185 to 220 MPa, and for tensile strength proof, pass 230 MPa or more. Evaluation (strength) was rejected.
The ear ratio was calculated from the following equation by measuring a cup height in the rolling direction after forming a cup by squeezing a blank having a diameter of 57 mm with a 33 mm punch.
Ear rate (%) = {(average mountain height−average valley height) / average cup height} × 100
Regarding the ear rate, 2.8% or less was regarded as acceptable (◯), and the others were regarded as unacceptable (x). As for the surface quality, no wrinkles, blisters, seizures, surface scratches or surface oxidation occurred, and the others were regarded as acceptable (◯), and the others were regarded as unacceptable. Regarding the deep drawability, the case where the DR could be continuously formed without cracking was determined to be acceptable (◯), and the others were rejected.

The above evaluation results are shown in Tables 3 and 4.

In Invention Examples 1 to 24, precipitation during hot rolling and annealing was suppressed, an appropriate texture could be obtained, and a good ear rate was exhibited. Also, an appropriate strength was obtained, and there was no generation of cracks or wrinkles during deep drawing, and an aluminum alloy having deep drawability and low ear ratio was obtained.

In Comparative Example 25, the Si content of the aluminum alloy was large, and the amount of intermetallic compound deposited was large. As a result, the formation of the Cube orientation was suppressed, leading to the development of 45-degree ears and the ear rate deteriorated.

In Comparative Example 26, the Fe content of the aluminum alloy was large, and coarse crystals were increased. As a result, recrystallization around the crystallized substance became dominant at the time of recrystallization, leading to the development of 45-degree ears of the final plate, and the ear rate was deteriorated.

In Comparative Example 27, since the Cu content was small, the yield strength and the tensile strength were lowered. As a result, cracks occurred during deep drawing.

In Comparative Example 29, since the Mn content was small, the yield strength and the tensile strength were lowered. As a result, cracks occurred during deep drawing.

In Comparative Example 31, since the Mg content was small, the material strength decreased. As a result, cracks occurred during deep drawing.

In Comparative Example 28, the yield strength was too high because of the high Cu content. For this reason, wrinkles are generated during deep drawing, resulting in deterioration of the surface quality.

In Comparative Example 30, the yield strength was too high due to the high Mn content. For this reason, wrinkles are generated during deep drawing, resulting in deterioration of the surface quality.

In Comparative Example 32, the yield strength was too high due to the high Mg content. For this reason, wrinkles were generated during deep drawing, resulting in deterioration of the surface quality.

In Comparative Example 33, since the homogenization temperature was low, recrystallization was inhibited by the second phase particles, and the rolled structure remained in the hot rolled sheet structure. As a result, the driving force for recrystallization became too high and the texture of the intermediate annealed plate was randomized, leading to the development of the 45-degree ears of the final plate and the ear rate deteriorated.

In Comparative Example 35, since the homogenization time was short and the finishing temperature of hot finish rolling was low, recrystallization was inhibited by the second phase particles, and the rolled structure remained in the hot rolled sheet structure. As a result, the driving force for recrystallization became too high and the texture of the intermediate annealed plate was randomized, leading to the development of the 45-degree ears of the final plate and the ear rate deteriorated.

In Comparative Example 34, since the homogenization temperature was high and the start temperature and end temperature of hot rough rolling were high, swelling, surface oxidation, and baking occurred, and the surface quality deteriorated.

In Comparative Example 36, since the start temperature and end temperature of hot rough rolling were low and the end temperature of hot finish rolling was low, the driving force of recrystallization decreased and the rolling structure remained. As a result, the formation of the Cube orientation was suppressed during the intermediate annealing, leading to the development of 45 degree ears and the ear rate being deteriorated.

In Comparative Example 37, the finish temperature of hot finish rolling was high, and seizure occurred on the surface. Moreover, the secondary cold rolling rate was high, the proof stress was too high, and wrinkles were generated. In addition to this, the secondary cold rolling rate was high, leading to the development of 45 degree ears and worsening of the ear rate.

In Comparative Example 38, the finish temperature of hot finish rolling was low, and the intermediate annealing temperature was low. As a result, the rolled structure remained, leading to the development of 45-degree ears in the final plate, and the ear rate deteriorated.

In Comparative Example 39, the finish temperature of hot finish rolling was low, and the rate of temperature increase during intermediate annealing was slow. As a result, recrystallization and precipitation competed to inhibit the formation of the Cube orientation, leading to the development of 45-degree ears in the final plate, and the ear rate deteriorated.

In Comparative Example 40, the rate of temperature increase during the intermediate annealing was too fast, and the plates were rubbed to cause surface scratches.

In Comparative Example 41, the secondary cold rolling rate was small and the proof stress and tensile strength were reduced. As a result, cracks occurred during deep drawing. Moreover, the intermediate annealing temperature was high, and seizure of cold-rolled oil occurred.

In Comparative Example 42, the finish temperature of hot finish rolling was low and the intermediate annealing time was short. As a result, a rolled structure remained, and 45-degree ears developed in the final plate, leading to deterioration of the ear rate.

In Comparative Example 43, the primary cold rolling rate was small, and the S orientation could not be sufficiently developed in the matrix. As a result, the number of nucleation sites in the Cube orientation decreased, and the ears developed 45 degrees on the final plate, leading to a deterioration in the ear rate.

In Comparative Example 44, the primary cold rolling rate is high, the recrystallization driving force before annealing is increased, the formation amount of the Cube orientation is decreased, and the 45-degree ear of the final plate is developed, leading to deterioration of the ear rate. Also, cracks occurred during deep drawing.

As described above, by controlling the texture and strength, it was possible to obtain a low ear ratio and good deep drawability even in an intermediate annealing process using a box-type annealing furnace. Moreover, since the continuous annealing furnace is not used, the manufacturing cost can be suppressed, and at the same time, the cost is expected to be reduced in equipment investment.

Claims

Si: 0.10 to 0.60 mass%, Fe: 0.10 to 0.80 mass%, Cu: 0.05 to 0.25 mass%, Mn: 0.80 to 1.50 mass%, Mg: 0.80 to 1. An aluminum alloy plate containing an aluminum alloy composed of the balance Al and unavoidable impurities, including 1.30 mass%, and having been made into a final plate through at least a hot rolled plate and an intermediate annealed plate from the ingot of the aluminum alloy, The Cube orientation density (CubeO) in the plate is 2.00 times or more than the random orientation density, and the ratio of CubeO to S orientation density (SO) (CubeO / SO) is 0.40 to 1.00. An aluminum alloy for a DR can body characterized by having a yield strength of 180 to 220 MPa and a tensile strength of 230 MPa or more after baking. .
The aluminum alloy plate for DR can body according to claim 1, wherein the electrical conductivity of the hot rolled plate is 36.0 to 43.0% IACS.
The Cube orientation density (CubeO) in the intermediate annealing plate is 4.00 times or more than the random orientation density, and the ratio of CubeO to R orientation density (RO) (CubeO / RO) is 1.00 or more. The aluminum alloy plate for DR can body according to claim 1 or 2.
The method for producing an aluminum alloy plate for a DR can body according to any one of claims 1 to 3, wherein Si: 0.10 to 0.60 mass%, Fe: 0.10 to 0.80 mass%, Cu A casting process for casting an aluminum alloy containing 0.05 to 0.25 mass%, Mn: 0.80 to 1.50 mass%, Mg: 0.80 to 1.30 mass%, and the balance Al and inevitable impurities; A homogenization process for homogenizing the ingot; a hot rolling process for hot rolling the homogenized ingot; a primary cold rolling process for the hot rolled sheet; and annealing the primary cold rolled sheet A method for producing an aluminum alloy plate for a DR can body, comprising: an intermediate annealing step to perform; and a secondary cold rolling step for the intermediate annealing plate.
In the homogenization step, the ingot is treated at 580 to 620 ° C. for 1 to 12 hours, and the hot rolling step ends with a hot rough rolling step with a start temperature of 450 to 610 ° C. and an end temperature of 450 to 550 ° C. A hot finish rolling stage at a temperature of 330 to 380 ° C., wherein a rolling rate of the primary cold rolling process is 85 to 95%, and in the intermediate annealing process, the primary cold rolled sheet has a temperature range of 200 ° C. or higher. The temperature is increased to an annealing temperature of 300 to 450 ° C. at an average temperature increase rate of 10 to 100 ° C./hour, and then maintained at the annealing temperature for 1 to 4 hours. The rolling rate in the secondary cold rolling step is 20 to The manufacturing method of the aluminum alloy plate for DR can bodies of Claim 4 which is 40%.
The method for producing an aluminum alloy plate for a DR can body according to claim 4 or 5, further comprising a final annealing step of annealing the secondary cold rolled plate after the secondary cold rolling step.
In the final annealing step, the secondary cold-rolled sheet is heated to an annealing temperature of 140 to 190 ° C. at an average heating rate of 10 to 80 ° C./hour in a temperature range of 200 ° C. or higher, and then 2 ° C. at the annealing temperature. The method for producing an aluminum alloy plate for a DR can body according to claim 6, which is maintained for 4 hours.