KR101315653B1 - Fabrication method of al alloy sheets having high deep drawability by asymmetric rolling - Google Patents

Abstract

PURPOSE: A method for manufacturing an aluminum alloy plate with excellent deep-drawing properties caused by asymmetry rolling is provided to obtain an aluminum alloy plate in which the mean plastic-strain ratio is remarkably excellent in comparison with an existing aluminum alloy plate. CONSTITUTION: A method for manufacturing an aluminum alloy plate with excellent deep-drawing properties caused by asymmetry rolling includes the following steps of: primarily asymmetry-rolling an aluminum alloy at a reduction rate of 55-95% and annealing at a temperature of 300-550°C; and secondarily asymmetry-rolling or symmetry-rolling the aluminum alloy at a reduction rate of 15-25% and annealing at a temperature of 300-550°C. The mean plastic-strain ratio of the aluminum plate is increased by 1.21-2.13 times in comparison with an initial sample. The absolute value of Δr is lowered by 0.58-0.01 times.

Description

Fabrication method of Al alloy sheets having high deep drawability by asymmetric rolling}

The present invention relates to a method for manufacturing an aluminum alloy sheet by asymmetrical rolling, and more particularly, to improve deep drawing by thermally annealing after primary asymmetrical rolling and thermal annealing, secondary asymmetrical rolling or secondary symmetrical rolling. It relates to a method for producing an aluminum alloy sheet material.

Aluminum alloy has low specific gravity, which makes it possible to lighten the product. Therefore, when aluminum alloys are applied to automobiles, by improving fuel economy, CO ₂ is reduced to reduce environmental pollution, which is in the spotlight as a material to replace automotive steel sheets.

However, the aluminum alloy sheet has a disadvantage in that the plastic deformation ratio (r value or Lankford parameter) indicating deep drawing property is lower than that of the steel sheet, and thus the manufacturing cost increases because the molding process must be repeated several times in molding. The reason for this is that aluminum is rolled and completely thermally annealed. The thermally annealed aluminum alloy sheet has many {001} <100> components, which are cubic aggregates, so that the plastic deformation ratio is low and the deep drawing property is poor. In the case of the steel sheet, it is known that a large plastic strain ratio can be obtained because there are a lot of γ-fiber texture components of the ND // <111> texture, so that the deep drawing property is good. Here, ND (normal direction) means a direction perpendicular to the plate surface.

Therefore, many researchers have continued to increase the plastic deformation ratio by increasing the ND // <111> aggregate structure of aluminum alloy sheet by using shear deformation of asymmetrical rolling. Many previous researchers thought that asymmetrical rolling of the FCC crystal structure caused shear deformation in asymmetrical rolling, so that the γ-fiber texture was well developed, which would increase the plastic deformation ratio. However, even after thermally annealing the aluminum alloy sheet after the first asymmetrical rolling, the plastic strain ratio does not reach the desired level.

The present invention provides a method for producing an aluminum alloy sheet having excellent deep drawing property, and an object thereof.

In order to achieve the above object, the present invention provides a high plastic strain ratio and a Δr absolute value through the first asymmetrical rolling and thermal annealing of the aluminum alloy material and the second asymmetrical rolling or the second symmetrical rolling and thermally annealing. It is to manufacture a low aluminum alloy sheet material. In general, in order to increase the deep drawing property of the metal sheet, the plastic deformation ratio should be high and the Δr absolute value should be low.

The aluminum alloy sheet produced according to the invention has a low rotational cubic texture which lowers the plastic strain ratio and increases the Δr absolute value (| Δr |), increases the plastic strain ratio, and increases the Δr absolute value (| Δr | Γ-fiber aggregates, ie, ND // <111> aggregates, develop well across all thickness layers. Therefore, the plastic strain ratio is higher than that of the initial specimen and the Δr absolute value (| Δr |) is lowered.

According to a preferred embodiment of the invention, the method for producing an aluminum alloy sheet, the first step of asymmetrically rolling the aluminum alloy material at a reduction rate of 55-95% and heat-annealing at 300-550 ℃, and

Secondary asymmetrical or symmetrical rolling at a reduction rate of 15-25%, and thermally annealing at 300-550 ℃.

The first asymmetrical rolling of the aluminum alloy sheet produces both the shear deformed assembly {001} <110> and the γ-fiber texture ND // <111> aggregate. Therefore, the deep drawing property of {001} <110> and the rotational cubic aggregate structure which lowers the plastic strain ratio and raises the absolute value of Δr (| Δr |) in the first (once) asymmetrically rolled aluminum sheet. Since the ND // <111> aggregate structure, which is a γ-fiber aggregate structure that increases the value and decreases the absolute value of Δr (| Δr |), is developed at the same time, the plastic deformation ratio does not significantly improve and the Δr absolute value (| Δr |) is increased. It doesn't get much lower.

Therefore, in the present invention, the development of the rotational cubic aggregate structure {001} <110>, which lowers the plastic strain ratio and increases the Δr absolute value (| Δr |) in the aluminum alloy sheet, lowers the plastic strain ratio and increases the Δr absolute value. The ND // <111> aggregates, a γ-fiber aggregate that lowers (| Δr |), were developed to develop well in all thickness layers. In other words, asymmetrical rolling of aluminum alloy material is made into two stages of primary and secondary, followed by thermal annealing at each stage after asymmetrical rolling, or thermal annealing at each stage after primary asymmetrical rolling and secondary symmetrical rolling. . In the present invention, after the first and second asymmetrical rolling or the second symmetrical rolling, thermal annealing increases the average plastic deformation ratio and decreases the absolute value of Δr (| Δr |).

According to the present invention, it is preferable that the first asymmetrical rolling is performed with the alloying material at a reduction ratio of 55-95%. When the reduction ratio of the first asymmetric rolling is in the range of 55% to 95%, the γ-fiber texture ND // <111> develops well, and the average plastic deformation ratio of the initial specimen is greatly increased and the absolute value of Δr (| △ r |) is significantly lowered.

As described above, the first asymmetrically rolled aluminum alloy plate is preferably heat-annealed at 300-550 ° C. When thermal annealing was performed in the range of 300 ℃ ~ 550 ℃, the development of rotational cubic tissue {001} <110> was lowered and the γ-fiber texture ND // <111> developed well. The ratio is greatly increased and the absolute value of Δr (| Δr |) is significantly lowered.

Heat-annealed aluminum alloy sheet material is preferably secondary asymmetrical rolling or secondary symmetrical rolling at 15-25% reduction rate. When the rolling reduction rate of the secondary rolling is 15 to 25%, the development of the rotational cubic structure {001} <110> is lowered and the γ-fiber texture ND // <111> is well developed. Is greatly increased and the absolute value of Δr (| Δr |) is significantly lowered.

As described above, the second asymmetrically rolled or the second symmetrically rolled aluminum alloy plate is preferably heat-annealed at 300-550 ° C. When thermal annealing was performed at 300 ℃ ~ 550 ℃, the development of rotational cubic aggregate {001} <110> was lowered and the γ-fiber aggregate ND // <111> developed well. The absolute value of Δr (| Δr |) is greatly lowered.

In the present invention, asymmetrical rolling is a common rolling method. In general, asymmetrical rolling has two methods of making the difference in the circumferential rotational speed by rotating the two rolls having the same diameter or different diameters of the upper roll and the lower roll at different angular speeds. In the present invention, asymmetrical rolling is not particularly limited among the two methods. In the experiment of the present invention, an example in which the roll rotational circumferential ratio of the upper roll and the lower roll is 1: 1.5-3 when asymmetrically rolled by the circumferential rotational speed difference is presented. In the present invention, when controlling the roll rotational speed ratio of the upper and lower rolls and the lower roll, it is possible to selectively select which of the upper and lower rolls the peripheral speed of the upper and lower rolls is relatively high. In the experiment of the present invention, the first and second asymmetrical rolling and the second symmetrical rolling are shown an example of rolling in a non-lubricated state.

The aluminum alloy material applied to the present invention is not particularly limited and may be applied to various aluminum alloy plate materials such as AA1000 series, AA3000 series, AA5000 series and AA6000 series. This aluminum alloy material applies what was manufactured according to a conventional method. For example, the molten aluminum alloy is cast and rolled according to a conventional casting method to produce an aluminum alloy sheet.

In the aluminum alloy sheet produced according to the present invention, the rotational cubic texture {001} <110> is lowered, and the? -Fiber texture, that is, the ND // <111> texture, is well developed over all the thickness layers.

According to the present invention, an aluminum alloy sheet material having a significantly higher average plastic deformation ratio than that of the related art is provided. Such alloy sheet material is obtained by a manufacturing method capable of mass production. In addition, the aluminum alloy sheet material provided according to the present invention has a significantly lower Δr absolute value | Δr | .

On the other hand, the aluminum alloy sheet material provided by the present invention can be applied to a variety of molding processing, in particular will have the optimum characteristics for the car body or parts of the automobile.

1, 3, 5, and 7 are (111) pole figures showing an example of the texture of the aluminum alloy sheet material produced according to the embodiment of the present invention.
2, 4, 6, and 8 are ODF contour diagrams at Ψ ₂ = 45 ° of the aluminum alloy sheet produced according to the embodiment of the present invention.
9, 10, 11, and 12 are graphs showing changes in the plastic strain ratio, the average plastic strain ratio and the Δr absolute value ( | Δr | ) of the aluminum alloy sheet produced according to the embodiment of the present invention.

AA1050 aluminum alloy sheet material having a thickness of 3 mm was used. The aluminum sheet was marked with the rolling direction and named initial specimen.

The initial specimens were rolls having a diameter ratio of upper and lower rolls of 1: 1 and a ratio of 1: 1.5-3. In the non-lubricated state, the final reduction was first asymmetrically rolled to 60-90%. In the first asymmetrical rolling, each rolling was passed at a rate of about 40% reduction to achieve a final reduction rate of 60-90%. The first 60-90% asymmetrically rolled aluminum alloy sheet was measured for change of texture after heat-loosing in a salt bath at 400-500 ° C for 60 minutes. After the first asymmetrical rolling, the thermally annealed aluminum alloy sheet was 10-25% secondary asymmetrically rolled or symmetrically rolled, and the change in the texture was measured after thermally annealing in a salt bath at 350-500 ° C for 15-60 minutes. .

The aluminum sheet measured the pole figure of the surface perpendicular | vertical to ND after rolling. In order to eliminate the friction and roughness effects of the rolling rolls on asymmetrically rolled aluminum alloy sheets, 1/10 thicknesses are removed mechanically and chemically from the upper and lower layers from the surface of the thick layer, each named S = ± 0.9. The half thickness layer, which is the middle layer, was named S = 0. Specimens of each of these three layers were measured for (111), (200) and (220) incomplete pole figures using Schultz reflection of Co-Kα X-rays. Based on the measured pole figure, the Orientation Distribution Function (ODF) was obtained using Bunge's method to obtain the plastic strain ratio.

Here, the plastic strain ratio r is defined as the true strain in the width direction / true strain in the thickness direction.

In this study, the plastic strain ratio was calculated using the measured pole viscosity values in each direction. Using the measured pole figure, the average plastic strain ratio () and the absolute value of Δr ( | Δr | ) were calculated from the plastic strain ratio in each direction using the following equation.

[Relationship 1]

) = (r₀ + 2r₄₅ + r₉₀) / 4 , Average plastic strain

) = (r ₀ + 2r ₄₅ + r ₉₀ ) / 4,

[Relation 2]

Δr absolute value (| △ r |) = ( r 0 - 2r 45 + r ₉₀ ) / 2

Here, r ₀ , r _45, and r ₉₀ refer to the plastic strain ratios obtained from the tensile test specimens fabricated in a direction forming 0 °, 45 °, and 90 ° with RD, respectively.

Tables 1, 2, 3, and 4 below show the measurement results for each manufacturing condition. In addition, the (111) pole figure measurement results of the specimens corresponding to Table 1, 2, 3, 4 are shown in Figures 1, 3, 5, 7 and ODF is shown in Figures 2, 4, 6, 8.

division
Manufacture conditions
Plastic strain ratio

)Average Plastic Strain Ratio
(

)
| △ r |
0 ° 45 ° 90 °

Growth rate | △ r | Growth rate A Initial Psalm 0.93 0.18 1.15 0.61 1.0 0.86 1.0 B-1 Primary asymmetrical rolling (90% reduction) 0.39 0.64 0.27 0.48 0.79 0.31 0.36 C-1 After 1st asymmetrical rolling (90% reduction), heat unwind at 500 ℃ for 1 hour 0.82 0.83 0.55 0.76 1.25 0.15 0.17 D-1 After the first asymmetrical rolling (90% reduction), the specimens heat-annealed at 500 ° C for 1 hour are subjected to the second asymmetrical rolling (10% reduction). 0.83 0.75 0.63 0.74 1.21 0.02 0.02 D-2 After the first asymmetrical rolling (90% reduction), the specimen was heat-annealed at 500 ° C for 1 hour, and the second asymmetrical rolling (10% reduction) was then thermally released at 500 ° C for 1 hour. 0.62 0.67 0.61 0.63 1.03 0.08 0.09 D-3 After the first asymmetrical rolling (90% reduction), the specimens heat-annealed at 500 ° C for 1 hour are subjected to the second asymmetrical rolling (20% reduction). 1.02 0.88 1.48 1.07 1.75 0.37 0.43 D-4 After the first asymmetrical rolling (90% reduction), the sample was heat-annealed at 500 ° C for 1 hour, and the second asymmetrical rolling (20% reduction rate) was then heated at 500 ° C for 1 hour. 1.42 1.30 1.16 1.30 2.13 0.01 0.01

division
Manufacture conditions
Plastic strain ratio

)Average Plastic Strain Ratio
(

)
| △ r | 0 ° 45 ° 90 °

Growth rate | △ r | Growth rate A Initial Psalm 0.93 0.18 1.15 0.61 1.0 0.86 1.0 B-1 Primary asymmetrical rolling (90% reduction) 0.39 0.64 0.27 0.48 0.79 0.31 0.36 C-1 After 1st asymmetrical rolling (90% reduction), heat unwind at 500 ℃ for 1 hour 0.82 0.83 0.55 0.76 1.25 0.15 0.17 E-1 Secondary symmetrical rolling (10% rolling reduction) of the specimens heat-annealed at 500 ° C for 1 hour after the first asymmetric rolling (90% rolling reduction) 0.88 0.96 0.62 0.86 1.41 0.22 0.26 E-2 After the first asymmetrical rolling (90% reduction), the sample was heat-annealed at 500 ° C for 1 hour, and then the thermally unrolled specimen at 500 ° C for 1 hour after the second symmetrical rolling (10% reduction). 0.57 0.64 0.47 0.58 0.95 0.12 0.14 E-3 After the first asymmetrical rolling (90% reduction), the specimen annealed at 500 ℃ for 1 hour is subjected to secondary symmetrical rolling (20% reduction). 0.64 0.97 0.74 0.83 1.36 0.28 0.33 E-4 After the first asymmetrical rolling (90% reduction), the specimen was heat-annealed at 500 ° C for 1 hour, and then subjected to the second symmetrical rolling (20% reduction) at 500 ° C for 1 hour. 0.77 0.96 1.03 0.93 1.52 0.06 0.07

division
Manufacture conditions
Plastic strain ratio

)Average Plastic Strain Ratio
(

)
| △ r | 0 ° 45 ° 90 °

Growth rate | △ r | Growth rate A Initial Psalm 0.93 0.18 1.15 0.61 1.0 0.86 1.0 F-1 After the first asymmetrical rolling (60% reduction rate), the sample was heat-annealed at 500 ℃ for 1 hour, and the second asymmetrical rolling (15% reduction rate) was then heated at 500 ℃ for 1 hour. 1.63 0.83 0.93 1.05 1.72 0.45 0.52 F-2 After the first asymmetrical rolling (60% reduction), the specimen was heat-annealed at 500 ° C for 1 hour, and the second asymmetrical rolling (20% reduction ratio) was then thermally released at 500 ° C for 1 hour. 1.2 0.96 0.54 0.91 1.49 0.09 0.10 F-3 After the first asymmetrical rolling (60% reduction rate), the sample was heat-annealed at 500 ° C for 1 hour, and the second asymmetrical rolling (25% reduction rate) was then heat-released at 500 ° C for 1 hour. 1.27 0.68 0.63 0.81 1.33 0.27 0.31 F-4 After the first asymmetrical rolling (70% reduction rate), the sample was heat-annealed at 500 ° C for 1 hour, and the second asymmetrical rolling (15% reduction rate) was then heat-released at 500 ° C for 1 hour. 1.05 0.87 0.78 0.89 1.46 0.04 0.05 F-5 After the first asymmetrical rolling (70% reduction), the specimen was heat-annealed at 500 ° C for 1 hour, and the second asymmetrical rolling (20% reduction ratio) was then thermally released at 500 ° C for 1 hour. 1.13 0.81 0.5 0.82 1.34 0.002 0.00 F-6 After the first asymmetrical rolling (70% reduction), the sample was heat-annealed at 500 ° C for 1 hour, and the second asymmetrical rolling (25% reduction rate) was then heated at 500 ° C for 1 hour. 1.03 0.49 0.95 0.74 1.21 0.5 0.58

division
Manufacture conditions
Plastic strain ratio

)Average Plastic Strain Ratio
(

) | △ r | 0 ° 45 ° 90 °

Growth rate | △ r | Growth rate A Initial Psalm 0.93 0.18 1.15 0.61 1.0 0.86 1.0 B-1 Primary asymmetrical rolling (90% reduction) 0.39 0.64 0.27 0.48 0.79 0.31 0.36 C-2 After primary asymmetrical rolling (90% reduction)
1 hour heat release at 400 ℃ 0.71 0.48 0.97 0.66 1.08 0.36 0.41 G-1 After the first asymmetrical rolling (90% reduction)
The specimen was heat-annealed at 400 ° C for 1 hour.
2nd asymmetrical rolling (20% reduction) 0.46 0.69 0.40 0.56 0.92 0.26 0.30 G-2 After the first asymmetrical rolling (90% reduction)
The specimen was heat-annealed at 400 ° C. for 1 hour.
2nd asymmetrical rolling (20% reduction)
1 hour heat release at 450 ℃ 1.55 0.73 0.74 0.94 1.54 0.41 0.48 H-1 After 1st asymmetrical rolling (80% reduction), heat-annealed the specimen at 400 ° C for 1 hour, then 2nd asymmetrical rolling (20% reduction), thermally unrolled at 350 ° C for 15 minutes. 1.01 0.97 0.65 0.90 1.48 0.14 0.16 H-2 After 1st asymmetrical rolling (80% reduction), the sample was heat-annealed at 400 ° C for 1 hour, and then thermally released at 350 ° C for 30 minutes after secondary asymmetrical rolling (20% reduction). 0.86 0.84 0.57 0.78 1.28 0.12 0.14 H-3 After the first asymmetrical rolling (80% reduction rate) and the sample heat-annealed at 400 ° C for 1 hour, the sample was heat-annealed at 400 ° C for 30 minutes after the second asymmetrical rolling (20% reduction rate). 0.91 0.73 0.66 0.76 1.25 0.06 0.07 H-4 After the first asymmetrical rolling (80% reduction rate), the sample was heat-annealed at 400 ° C for 1 hour, and the second asymmetrical rolling (20% reduction rate) was then heat-released at 400 ° C for 1 hour. 0.6 0.79 0.95 0.78 1.28 0.02 0.02

In Figure 1 A ~ D-4 shows the (111) pole figure of the specimen corresponding to A ~ D-4 in Table 1. In Figure 2 A ~ D-4 represents the value of Ψ ₂ = 45 ° of the ODF (Azimuth distribution function) obtained by using the pole figure of Figure 1 specimens corresponding to A ~ D-4 of Table 1. In Figures 1 and 2, S = 0.9, S = 0, S = -0.9, by mechanical and chemical methods to remove 1/10 thickness in the upper and lower layers from the surface of the thickness layer of the aluminum alloy sheet, respectively S = ± 0.9 The half-thick layer, which is the middle layer, is named S = 0.

1,2A shows strong cubic texture {100} <100> with (111) pole figure and ODF of an initial specimen, respectively. In Table 1, the initial specimen of A had an average plastic deformation ratio of 0.61 and an absolute value of Δr (| Δr |) of 0.86. In Table 1, the average plastic deformation ratio and the increase rate of Δr absolute value (| Δr |) of other condition specimens were calculated based on the initial specimen of A. For example, the average plastic strain ratio of the A specimen and the increase rate of the absolute value of Δr are each 1.0 because the A specimen is a reference. The average plastic strain ratio and the increase rate of Δr absolute value of B-1 specimens were 0.79 and 0.36, respectively, based on the A specimen. The increase rate less than 1 means that the average plastic strain and the absolute value of Δr are smaller than the reference specimen A.

B-1 in FIGS. 1,2 shows the (111) pole figure and ODF of the first 90% asymmetrically rolled specimen. The specimen developed strong rotating cubic texture {001} <110> and weak γ-fiber texture ND // <111> across all thickness layers. In Table 1, the average plastic strain ratio of B-1 was 0.48, the average plastic strain growth rate was 0.79, the Δr absolute value was 0.31, and the Δr absolute value was 0.36.

C-1 in FIGS. 1 and 2 are the (111) poles and the ODF of the specimens heat-annealed at 500 ° C. for 1 hour after the first 90% asymmetrical rolling. Rotational cubic texture {001} <110> and weak γ-fiber texture ND // <111> developed over all thickness layers. In C-1 of FIGS. 1 and 2, the upper layer (S = 0.9) has a cubic texture and a rotating cubic texture, and the middle layer (s = 0) has a rotating cubic texture, a weak γ-fiber texture, and a lower layer (s = -0.9). ), Rotational cubic texture and weak γ-fiber texture developed. In Table 1, C-1 had an average plastic strain ratio of 0.76, an average plastic strain increase rate of 1.25, an Δr absolute value of 0.15 and an Δr absolute value increase of 0.17.

D-1 in FIGS. 1 and 2 are poles and ODF of the (111) poles of the specimens which were thermally annealed at 500 ° C. for 1 hour after the first 90% asymmetrical rolling. Weak rotational cubic texture {001} <110> and strong γ-fiber texture developed over all thickness layers. In FIG. 1,2C, the rotational cubic texture {001} <110> is located in the upper layer (s = 0.9) and the {112} <111>, {001} <130> and {332} <in the middle layer (s = 0). At the lower level (s = -0.9), the cubic crystals, {112} <111>, {113} <110> and {332} <023>, developed. As shown in Table 1, D-1 has an average plastic strain ratio of 0.74, an average plastic strain increase rate of 1.21, an Δr absolute value of 0.02 and an Δr absolute value of 0.02.

D-2 in FIGS. 1 and 2 shows the (111) poles of the specimens heat-annealed at 500 ° C for 1 hour after the first 90% asymmetrical rolling at 500 ° C. ODF. Weak rotational cubic texture {001} <110> and strong γ-fiber texture developed over all thickness layers. In FIG. 1, 2, {113} <332> and {331} <013> aggregates in the upper layer (s = 0.9), and cubic crystals in the middle layer (s = 0) {011} <110>, {331 } <123> and {331} <233> clusters, cubic crystals and {221} <122> and {331} <013> clusters were developed in the lower layer (s = -0.9). In Table 1, D-2 was 0.63 with an average plastic deformation ratio of 1.03, an average plastic deformation ratio of 1.03, an Δr absolute value of 0.08 and an Δr absolute value of 0.09.

D-3 in FIGS. 1 and 2 show the (111) poles and the ODF of the specimens subjected to a 90% asymmetrical rolling after the first 90% asymmetrical rolling and the specimens subjected to the second 20% asymmetrical rolling of the specimen. 1 and 2, rotational cubic texture was increased and weak γ-fiber texture was developed over all the thickness layers. {113} <013>, {113} <121> and {331} <013> aggregates in the upper layer (s = 0.9), {331} <110> and {113} <031 in the middle layer (s = 0) > In the lower layer (s = -0.9), {331} <110>, {113} <013> and γ-fiber aggregates developed. In Table 1, D-3 had an average plastic strain ratio of 1.07, an average plastic strain increase of 1.75, an absolute value of Δr of 0.37 and an increase of Δr absolute of 0.43.

D-4 in FIGS. 1 and 2 show poles of (111) poles of specimens heat-annealed at 500 ° C. for 1 hour after primary 90% asymmetrical rolling at 500 ° C. for 1 hour. ODF. 1 and 2, the rotating cubic texture disappeared and a strong γ-fiber texture, that is, a strong ND // <111> texture, developed over all the thickness layers. As shown in Table 1, D-4 is 1.30, the average plastic strain ratio is 2.13, the average plastic strain ratio is 2.13, the Δr absolute value is 0.01, and the Δr absolute value is 0.01. As a result, in Table 1, the average plastic deformation ratio of D-4 was 2.13 times higher than that of the initial specimen, and the absolute value of Δr was lowered to 1/86 (= 0.01) times. The reason is that γ-fiber texture ND // <111> is well developed by the second asymmetrical rolling and thermal annealing.

In Figure 3, A, B-1, C-1 ~ E-4 shows the (111) pole figure of the specimen corresponding to A, B-1, C-1 ~ E-4 in Table 2. In Figure 4, A, B-1, C-1 ~ E-4 is the ODF (Azimuth) obtained by using the pole figure of Figure 3 the specimen corresponding to A, B-1, C-1 ~ E-4 of Table 2 Value of Ψ ₂ = 45 °. In Figures 3 and 4, S = 0.9, S = 0, S = -0.9 is mechanically and chemically removed from the surface of the thickness layer of the aluminum alloy sheet in the upper and lower layers by mechanical and chemical methods, respectively, S = ± 0.9 The half-thick layer, which is the middle layer, is named S = 0.

3A and 4A show the (111) poles and the ODF of the initial specimen, respectively. In Table 2, the initial specimen of A had an average plastic deformation ratio of 0.61 and an absolute value of Δr of 0.86. In Table 2, the average plastic strain ratio and the increase rate of Δr absolute value of the other condition specimens were calculated based on the initial specimen of A. For example, the average plastic strain ratio of the A specimen and the increase rate of the absolute value of Δr are each 1.0 because the A specimen is a reference. The average plastic strain ratio and the increase rate of Δr absolute value of B-1 specimens were 0.79 and 0.36, respectively, based on the A specimen. Here, an increase of less than 1 means that the average plastic strain and the absolute value of Δr are smaller than the reference specimen A.

B-1 in FIGS. 3 and 4 are the (111) poles and the ODF of the first 90% asymmetrically rolled specimens, respectively. This specimen developed a rotating cubic texture {001} <110> and a weak γ-fiber texture ND // <111> over all thickness layers. The average plastic strain ratio of B-1 was 0.48, the average plastic strain ratio was 0.79, the absolute value of Δr was 0.31 and the rate of increase of the absolute value of Δr was 0.36.

C-1 in FIGS. 3 and 4 are the (111) poles and the ODF of the specimens heat-annealed at 500 ° C. for 1 hour after the first 90% asymmetrical rolling. Rotational cubic texture {001} <110> and weak γ-fiber texture ND // <111> developed over all thickness layers. In C-1 of Figs. 3 and 4, the upper layer (S = 0.9) has a cubic texture and a rotating cubic texture, and the middle layer (s = 0) has a rotating cubic texture, a weak γ-fiber texture, and a lower layer (s = -0.9). ), Rotational cubic texture and weak γ-fiber texture developed. C-1 had an average plastic deformation ratio of 0.76, an average plastic deformation ratio of 1.25, an absolute value of Δr of 0.15, and an increase of 0.17 of an absolute value of Δr.

E-1 in FIGS. 3 and 4 is a (111) pole figure and an ODF of a specimen in which the sample was thermally annealed at 500 ° C. for 1 hour after the first 90% asymmetrical rolling. Weak rotational cubic texture and weak γ-fiber texture developed over all thickness layers. 3,4, {113} <332> and {331} <233> aggregates in the upper layer (S = 0.9) and {113} <332> and {331} <in the middle layer (s = 0). 233> At the lower level (s = -0.9), cubic, {113} <031> aggregates developed. E-1 had an average plastic deformation ratio of 0.86 and an average plastic deformation ratio of 1.41, an Δr absolute value of 0.22 and an Δr absolute value of 0.26.

E-2 in FIGS. 3 and 4 shows a (111) pole figure of a specimen that was thermally annealed at 500 ° C. for 1 hour after the first 90% asymmetrical rolling at 500 ° C. for 1 hour. ODF. Weak rotational cubic texture and strong γ-fiber texture developed over all thickness layers. 3,4, {113} <121>, {331} <110> and {331} <233> aggregates in the upper layer (s = 0.9), and {113} in the middle layer (s = 0). <121> and {331} <110> aggregates were developed and {113} <332> and {331} <110> aggregates were developed in the lower layer (s = -0.9). E-2 had an average plastic deformation rate of 0.58, an average plastic deformation rate of 0.95, an Δr absolute value of 0.12 and an Δr absolute value of 0.14.

E-3 in FIGS. 3 and 4 are (111) poles and ODF of a specimen obtained by performing a first 90% asymmetrical rolling and then thermally annealing the specimen at 500 ° C. for 1 hour. 3 and 4, {113} <332>, {113} <110> and {331} <233> aggregates are located in the upper layer (s = 0.9), and {113} <332 in the middle layer (s = 0). >, {331} <013> and {331} <233> collectives, while downstairs (s = -0.9), {113} <332>, {113} <031> and {331} <110> collectives Developed. E-3 had an average plastic deformation rate of 0.83 and an average plastic deformation rate of 1.36, an Δr absolute value of 0.28 and an Δr absolute value of 0.33.

E-4 in FIGS. 3 and 4 shows the (111) poles of the specimens heat-annealed at 500 ° C. for 1 hour after the first 90% asymmetrical rolling at 500 ° C. for 1 hour. ODF. 3 and 4, the {113} <332>, {113} <121> and {110} <233> aggregates are located in the upper layer (s = 0.9), and {113} <031 in the middle layer (s = 0). > And {113} <332> aggregates were developed, and {113} <332>, {113} <332> and {331} <110> aggregates were developed in the lower layer (s = -0.9). E-4 had an average plastic deformation rate of 0.93 and an average plastic deformation rate of increase of 1.52, an absolute value of Δr of 0.06 and an increase of 0.07 of an absolute value of Δr. As a result, the average plastic deformation ratio of E-4 was 0.93 times higher than that of the initial specimen, and the absolute value of Δr was lowered to 3/43 (= 0.07) times. This is because the rotational cubic structure disappeared by the second symmetrical rolling and thermal annealing.

In Figure 5, A ~ F-6 shows the (111) pole and ODF of the specimen corresponding to A ~ F-1 in Table 3. In Figure 6, A ~ F-6 shows the value of Ψ ₂ = 45 ° of the ODF (Azimuth distribution function) obtained by using the pole figure of FIG. In Figures 5 and 6, S = 0.9, S = 0, S = -0.9 is mechanically and chemically removed from the surface of the thickness layer of the aluminum alloy sheet in the upper and lower layers by mechanical and chemical methods, respectively, S = ± 0.9 The half-thick layer, which is the middle layer, is named S = 0.

5A and 6A show cubic crystal texture with (111) pole figure and ODF of the initial specimen, respectively. In Table 3, the initial specimen of A had an average plastic deformation ratio of 0.61 and an absolute value of Δr of 0.86. In Table 3, the average plastic deformation ratio and the increase rate of Δr absolute value of the other condition specimens were calculated based on the initial specimen of A. For example, the average plastic strain ratio of the A specimen and the increase rate of the absolute value of Δr are each 1.0 because the A specimen is a reference. The average plastic strain ratio and the increase rate of Δr absolute value of B-1 specimens were 0.79 and 0.36, respectively, based on the A specimen. A growth rate less than 1 means that the average plastic strain and the absolute value of Δr are smaller than the reference specimen A.

5,6 F-1 shows the (111) poles of the specimens heat-annealed at 500 ° C. for 1 hour after the first 60% asymmetrical rolling and then heat-annealed at 500 ° C. for 1 hour. ODF. The specimens developed the rotating cubic texture {001} <110> and the weak γ-fiber texture ND // <111> in the middle layer (s = 0) and the {113} (031), {331} (013) and {110} <332> Aggregates developed. The average plastic strain ratio of F-1 was 1.05, the average plastic strain ratio was 1.72, the Δr absolute value was 0.45 and the Δr absolute value was 0.52.

5,6 F-2 shows the (111) poles of the specimens heat-annealed at 500 ° C. for 1 hour after the first 60% asymmetrical rolling. ODF. This specimen developed weakly rotating cubic aggregates {001} <110> and weak γ-fiber aggregates ND // <111> in the middle layer (s = 0), {113} <332> and {110} <110>. Aggregation developed. In F-2, the average plastic deformation ratio was 0.91. The average plastic deformation ratio was 1.49, the Δr absolute value was 0.09, and the Δr absolute value was 0.10.

5,6 F-3 shows the (111) poles of the specimens heat-annealed at 500 ° C. for 1 hour after the first 60% asymmetrical rolling, and then heat-annealed at 500 ° C. for 1 hour. ODF. The specimens developed weak rotary cubic and weak γ-fiber aggregates in the middle layer (s = 0) and developed {113} <121>, {113} <031> and {110} <001> aggregates. . F-3 had an average plastic deformation ratio of 0.81 and an average plastic deformation ratio of 1.33, an Δr absolute value of 0.27 and an Δr absolute value of 0.31.

5,6 F-4 shows the (111) poles of the specimens heat-annealed at 500 ° C. for 1 hour after the first 70% asymmetrical rolling at 500 ° C. for 1 hour. ODF. The specimens developed weak rotary cubic and weak γ-fiber aggregates in the middle layer (s = 0) and {113} <332> and {113} (031). F-4 had an average plastic deformation rate of 0.89 and an average plastic deformation rate of 1.46, an Δr absolute value of 0.04 and an Δr absolute value of 0.05.

5, 6 F-5 shows the (111) pole figure and ODF of a specimen subjected to the second 20% asymmetrical rolling of the specimen heated at 500 ° C. for 1 hour after the first 70% asymmetrical rolling. The specimens showed increased rotational cubic texture in the middle layer (s = 0), weaker γ-fiber aggregates, and {113} <<121>, {331} <110> and {331} <233>. Developed. F-5 had an average plastic deformation ratio of 0.82 and an average plastic deformation ratio of 1.34, an Δr absolute value of 0.002 and an Δr absolute value of 0.00.

5,6 F-6 shows a (111) pole figure of a specimen heat-annealed at 500 ° C. for 1 hour after the first 70% asymmetrical rolling at 500 ° C. for 1 hour. ODF. The specimens had increased rotational cubic texture, weak γ-fiber texture, and {113} <<031> and {110} <233> texture in the middle layer (s = 0). F-6 had an average plastic deformation ratio of 0.74 and an average plastic deformation ratio of 1.21, an Δr absolute value of 0.5 and an Δr absolute value of 0.58. As a result, the average plastic deformation ratio of F-1 was 1.72 times higher than that of the initial specimen, and the absolute value of Δr was lowered to 0.52 times. The reason is that the rotational cubic texture is weakened by the second asymmetrical rolling and the thermal annealing, and the γ-fiber texture ND // <111> is well developed.

In Figure 7 A ~ H-1 shows the (111) pole and ODF of the specimen corresponding to A ~ H-1 in Table 3. In Figure 8, A ~ H-6 represents the value of Ψ ₂ = 45 ° of the ODF (Azimuth distribution function) obtained by using the pole figure of Figure 7 specimens corresponding to A ~ H-6 in Table 2. In Figures 5 and 6, S = 0.9, S = 0, S = -0.9 is mechanically and chemically removed from the surface of the thickness layer of the aluminum alloy sheet in the upper and lower layers by mechanical and chemical methods, respectively, S = ± 0.9 The half-thick layer, which is the middle layer, is named S = 0.

7, 8A shows the cubic crystal texture with the (111) pole figure and ODF of the initial specimen, respectively. In Table 4, the initial specimen of A had an average plastic deformation ratio of 0.61 and an absolute value of Δr of 0.86. In Table 4, the average plastic strain ratio and the increase rate of Δr absolute value of the other condition specimens were calculated based on the initial specimen of A. For example, the average plastic strain ratio of the A specimen and the increase rate of the absolute value of Δr are each 1.0 because the A specimen is a reference.

7, 8 B-1 are (111) poles and ODF of the first 90% asymmetrically rolled specimens, respectively. This specimen developed a rotating cubic texture {001} <110> and a weak γ-fiber texture ND // <111> over all thickness layers. The average plastic strain ratio of B-1 was 0.48, the average plastic strain ratio was 0.79, the absolute value of Δr was 0.31 and the rate of increase of the absolute value of Δr was 0.36.

7, 8 C-2 is the (111) pole and ODF of the specimen heat-annealed at 400 ℃ 1 hour after the first 90% asymmetrical rolling. In this specimen, {112} (111), rotational cubic texture {001} <110> and weak γ-fiber texture ND // <111> developed in the middle layer (s =). For C-2, the average plastic deformation rate was 0.66, and the average plastic deformation rate was 1.08, the Δr absolute value was 0.36, and the Δr absolute value was 0.41.

7, 8 G-1 shows the (111) pole and ODF of the specimen subjected to a 90% asymmetrical rolling after the first 90% asymmetrical rolling and the second 20% asymmetrically rolled specimen. The specimen developed a rotating cubic texture {001} <110> in the central layer (s = 0). The average plastic strain ratio of G-1 was 0.56, the average plastic strain growth rate was 0.92, the absolute value of Δr was 0.26, and the rate of increase of the absolute value of Δr was 0.30.

7, 8 G-2 shows the (111) poles of the specimen that was heat-annealed at 400 ° C. for 1 hour after the first 90% asymmetrical rolling, and was subjected to the annealing at 450 ° C. for 1 hour. ODF. The intermediate layer (s = 0) of this specimen developed {331} <013>, rotational cubic texture {001} <110> and weak γ-fiber texture ND // <111>. In G-2, the average plastic deformation rate was 0.94, and the average plastic deformation rate was 1.54, the Δr absolute value was 0.41 and the Δr absolute value was 0.48.

7,8 H-1 shows the (111) poles of the specimens heat-annealed at 400 ° C. for 1 hour after 80% asymmetrical rolling for 1 hour and then heat-annealed at 350 ° C. for 15 minutes after secondary 20% asymmetrical rolling. ODF. The intermediate layer (s = 0) of this specimen developed {113} <121>, {113} <110>, weakly rotating cubic and weak γ-fiber aggregates. H-1 had an average plastic deformation rate of 0.90 and an average plastic deformation rate of 1.48, an Δr absolute value of 0.14 and an Δr absolute value of 0.16.

7, 8 H-2 shows the (111) poles of the specimens heat-annealed at 400 ° C for 1 hour after the first 80% asymmetrical rolling at 350 ° C ODF. The intermediate layer (s = 0) of this specimen was composed of {113} <031>, {112} <132>, {110} <110>, {331} <112>, {331} <210>, and weakly rotating cubic textures. Weak γ-fiber aggregates developed. H-2 had an average plastic deformation ratio of 0.78 and an average plastic deformation ratio of 1.28, an Δr absolute value of 0.12 and an Δr absolute value of 0.14.

7, 8, H-3 is the (111) pole and ODF of the specimen after the first 70% asymmetrical rolling and the second 20% asymmetrical rolling of the sample heat-annealed at 400 ℃ 1 hour. The intermediate layer (s = 0) of this specimen was {113} <121>, 113} <110>, with weakly rotating cubic aggregates. H-3 had an average plastic deformation ratio of 0.76, an average plastic deformation ratio of 1.25, an Δr absolute value of 0.06 and an Δr absolute value of 0.07.

7, 8 shows the (111) poles of the specimens heat-annealed at 400 ° C. for 1 hour after the first 80% asymmetrical rolling at 400 ° C. for 1 hour. ODF. The intermediate layer (s = 0) of this specimen developed {113} <332>, {001} <120>, {223} <032>, {110} <221> and a rotating cubic texture. H-4 had an average plastic deformation ratio of 0.78 and an average plastic deformation ratio of 1.28, an Δr absolute value of 0.02 and an Δr absolute value of 0.02. As a result, the average plastic deformation ratio of G-2 was 1.54 times higher than that of the initial specimen, and the absolute value of Δr was reduced to 0.48 times. This is because the rotational cubic texture is lowered by the second asymmetrical rolling and the thermal annealing, and the γ-fiber texture ND // <111> is well developed.

9, 10, 11, and 12 are graphs showing changes in the plastic strain ratio and the Δr absolute value (| Δr |) of the aluminum alloy sheet produced according to the embodiments of the present invention shown in Tables 1,2,3,4. It is shown.

While preferred embodiments of the present invention have been described herein, many variations are possible within the spirit and scope of the invention, which are also intended to be included within the spirit of the invention.

In the experiment of the present invention described above, the first and second asymmetrical rolling is the ratio of the rotational rotational speed ratio of the upper roll and the lower roll is 1: 1.5-3, and the first and second rolling are in a non-lubricated state. Applied as an example. In addition, looking at the experimental results of the present invention, it can be seen that the average plastic deformation rate of the plate is lower than the absolute value Δr while increasing the initial specimen. The most optimal result can be seen that the average plastic deformation ratio is increased by 1.21 ~ 2.13 times and the Δr absolute value is lowered by 0.58 ~ 0.01 times than the initial specimen.

Claims (2)

Firstly asymmetrically rolling the aluminum alloy sheet at a reduction ratio of 55-95% and thermally annealing at 300-550 ° C., and
A method for producing an aluminum alloy sheet having excellent deep drawing property by asymmetrical rolling comprising the step of secondary asymmetrical rolling or symmetrical rolling at a reduction ratio of 15-25%, and thermal annealing at 300-550 ° C.
According to claim 1, The aluminum alloy sheet is an aluminum excellent in deep drawing by asymmetrical rolling, characterized in that the average plastic deformation ratio is increased by 1.21 ~ 2.13 times than the initial specimen, the Δr absolute value is lowered by 0.58 ~ 0.01 times Method for producing alloy sheet.

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