JP2023021838A - Aluminum alloy sheet for molding and method for manufacturing the same - Google Patents

Abstract

To provide an aluminum alloy sheet which can improve an effect for reducing a spring back amount by final pressing.SOLUTION: There is provided an aluminum alloy sheet for molding, wherein when hardness (Hv) is measured at an interval of 1/16 of a plate thickness in a plate thickness direction from a position of the depth of 1/2 of the sheet thickness to the sheet surface, a vertical axis is defined as hardness (Hv) and a horizontal axis is defined as a distance (mm) from the position of the depth of 1/2 of the sheet thickness, distribution of the hardness is plotted, a relation between the hardness (Hv) and the distance (mm) from the position of the depth of 1/2 of the sheet thickness is approximated by a primary function by the plot of the distribution of the hardness, and a gradient A of the primary function is determined by a least-square method, a value obtained by multiplying the gradient A by the sheet thickness (mm) is 10-28.SELECTED DRAWING: Figure 3

Description

TECHNICAL FIELD The present invention relates to a molding aluminum alloy sheet having a reduced amount of springback after press molding of the sheet material, and a method for producing the same.

In the press forming process of a plate material, when the material is bent, a dimensional shape defect occurs due to springback, in which the material returns to its original state by the amount of elastic deformation when the tool is released. Generally speaking, the harder the material, the greater the springback, and the greater the amount of springback. Therefore, in order to suppress dimensional and shape defects, it is necessary to lower the material strength and narrow the elastic deformation region of the stress-strain curve.

Therefore, conventionally, in order to reduce the amount of springback, decisive pushing is performed by applying pressure to the plate in the plate thickness direction. By this method, the stress in the plate thickness direction can be changed, and the in-plane stress of the plate material can be changed to suppress the springback. However, with this method, depending on the material, the amount of reduction in the amount of springback is small, so further measures are required.

For this reason, as a method for reducing the amount of springback, for example, Patent Document 1 discloses a layer harder than the average hardness from the surface layer to 1/4 plate thickness by incorporating a skin pass after solution treatment. A method for enhancing the shape fixability by providing is disclosed.

JP-A-2006-283138

However, in Patent Document 1, there is a problem that regions having a hardness higher than the average hardness are increased. As mentioned above, since springback is a plastic deformation related to elastic deformation regions, it is better to minimize regions that are harder than the average hardness.

Then, in order to reduce the amount of springback in press molding, the strength must be lowered. Therefore, it is not easy to produce an aluminum alloy plate having both high strength and low springback.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an aluminum alloy plate capable of improving the effect of reducing the amount of springback caused by a final push.

In order to solve the above problems, the present inventors have made extensive studies and found that the springback amount is reduced while maintaining high strength by having a specific hardness distribution gradient and plate thickness in the thickness direction. The present inventors have found that it is possible to obtain an aluminum alloy plate having excellent shape fixability, and have completed the present invention.

That is, in the present invention (1), the hardness (Hv) is measured at intervals of 1/16 of the plate thickness in the plate thickness direction from the position of 1/2 depth of the plate thickness to the plate surface, and the vertical axis is Hardness (Hv), plotting the hardness distribution with the horizontal axis as the distance (mm) from the position of 1/2 depth of the plate thickness, from the plot of the hardness distribution, hardness (Hv) and the distance (mm) from the position of 1/2 of the plate thickness is approximated by a linear function, and when the slope A of the linear function is obtained by the least squares method, the slope A and the plate thickness (mm) Provided is an aluminum alloy sheet for molding, characterized in that the value obtained by multiplying by is 10 to 28.

In the present invention (2), from the plot of the hardness distribution, the hardness (Hv) and the thickness The relationship of the distance (mm) from the position of 1/2 depth of is approximated by a linear function, the slope B1 of the linear function is obtained by the method of least squares, and among the plots of the hardness distribution, the plate thickness From the plot of the hardness distribution from the 1/2 depth position to the 1/4 thickness position, the hardness (Hv) and the distance from the 1/2 thickness position (mm ) is approximated by a linear function, and the slope B2 of the linear function is obtained by the method of least squares, the absolute value of the difference (B1-B2) between the slope B1 and the slope B2 is 10 or less. The object is to provide an aluminum alloy sheet for molding according to (1).

Further, the present invention (3) provides the aluminum alloy sheet for molding according to (1) or (2), characterized by having a tensile strength of 140.0 MPa or more.

Further, the present invention (4) provides an aluminum alloy sheet for forming according to any one of (1) to (3), which is made of a JIS5000 series aluminum alloy.

Further, the present invention (5) provides an aluminum alloy sheet for forming according to any one of (1) to (3), which is made of a JIS6000 series aluminum alloy.

In addition, the present invention (6) is a method for producing an aluminum alloy sheet for molding made of a JIS 5000 series aluminum alloy, comprising: (1a) a cold working rate of 70.0% or more; Performing a skin pass with a rolling reduction of 1.0 to 10.0%, (3a) performing three or more passes with a rolling reduction of 25.0% or less per pass of cold working, and (4a) stable Provided is a method for producing an aluminum alloy sheet for molding, characterized by performing at least one of treatment with a leveler after heat treatment.

In addition, the present invention (7) is a method for producing an aluminum alloy sheet for molding made of a JIS 6000 series aluminum alloy, in which (1b) the cold working rate is 70.0% or more, and (2b) after artificial aging treatment, (3b) Performing three or more passes with a rolling reduction of 25.0% or less per pass of cold working, and (4b) Solution Provided is a method for producing an aluminum alloy sheet for molding, characterized by performing at least one of treatment with a leveler after heat treatment or after artificial aging treatment.

ADVANTAGE OF THE INVENTION According to this invention, the aluminum alloy plate which can improve the reduction effect of the amount of springbacks by decisive pushing can be provided.

1 is a schematic cross-sectional view of an aluminum alloy sheet for forming according to the present invention; FIG. FIG. 4 is a hardness plot of Example A; FIG. 4 is a hardness plot of Example B; FIG. 4 is a hardness plot of Example C; FIG. 4 is a hardness plot of Example D; FIG. 4 is a hardness plot of Example E; FIG. 4 is a hardness plot of Example F; FIG. 4 is a hardness plot of Example G; FIG. 10 is a plot of the hardness of Comparative Example H; FIG. 4 is a plot of the hardness of Comparative Example I; FIG. 4 is a plot of hardness of 6000 series standard materials. FIG. 4 is a hardness plot of Example J; FIG. 4 is a hardness plot of Example K; FIG. 4 is a hardness plot of Example L; It is a plot figure of the hardness of 5000 series standard material.

The aluminum alloy plate for molding of the present invention is measured for hardness (Hv) at intervals of 1/16 of the plate thickness in the plate thickness direction from the position of 1/2 depth of the plate thickness to the plate surface, and the vertical axis The hardness (Hv ) and the distance (mm) from the position of half the thickness of the plate is approximated by a linear function, and when the slope A of the linear function is obtained by the least squares method, the slope A and the plate thickness (mm ) is 10 to 28.

The aluminum alloy sheet for molding of the present invention will be described with reference to FIGS. 1, 3 and 9. FIG. FIG. 1 is a schematic cross-sectional view of an aluminum alloy sheet for molding according to the present invention. FIG. 3 is a diagram plotting hardness distribution for Example B, with the vertical axis representing hardness (Hv) and the horizontal axis representing distance (mm) from a position half the plate thickness. . FIG. 9 is a diagram plotting the hardness distribution of Comparative Example H, with the vertical axis representing the hardness (Hv) and the horizontal axis representing the distance (mm) from the position half the plate thickness. .

The measurement position of hardness (Hv) will be described with reference to FIG. FIG. 1 is a cross-sectional view of an aluminum alloy plate 1 for forming, taken along a plane perpendicular to the plate surface. In FIG. 1, the position indicated by reference numeral 3 is the position at the depth of 1/2 of the plate thickness. That is, position 3 at a depth of 1/2 of the plate thickness is a position that is separated from the plate surface 7 in the plate thickness direction 6 by a length q of 1/2 of the plate thickness p. Further, the position indicated by reference numeral 5 is the position at the depth of 1/4 of the plate thickness. That is, the position 5 at a depth of 1/4 of the plate thickness is a position away from the plate surface 7 in the plate thickness direction 6 by a length r of 1/4 of the plate thickness p.

A method for obtaining the slope A will be described. Inclination A is obtained by measuring the hardness (Hv) at intervals of 1/16 of the plate thickness in the plate thickness direction from the position of the depth of 1/2 of the plate thickness to the plate surface, and the vertical axis is the hardness (Hv) And when plotting the hardness distribution with the horizontal axis as the distance (mm) from the position of 1/2 the plate thickness, it is obtained by the least squares method based on the plot of the hardness distribution It is the slope of a linear function obtained by approximating the relationship between the hardness (Hv) and the distance (mm) from a position half the thickness of the plate with a linear function. First, with respect to the cross section of the aluminum alloy plate for molding, hardness (Hv) is measured at intervals of 1/16 of the plate thickness p in the plate thickness direction 6 from the position 3 at the depth of 1/2 of the plate thickness to the plate surface position 4. to measure. Next, as shown in FIG. 3, the hardness (Hv) results at each measurement position are plotted with the vertical axis representing the hardness (Hv) and the horizontal axis representing the distance from the position half the plate thickness (mm ) and plotted as Next, from the plot of the obtained hardness distribution, the relationship between the hardness (Hv) and the distance (mm) from the position of half the thickness of the plate is approximated by a linear function, and the slope A of the linear function is obtained by the method of least squares. In Example B shown in FIG. 3, the slope A is determined to be 16 by the method of least squares. Further, in Comparative Example H, the slope A is obtained as 4.9 by the method of least squares as shown in FIG. 9 by the same procedure.

In the present invention, the hardness (Hv) is measured by a method conforming to JIS Z 2244. For example, an aluminum alloy plate is embedded in resin, mirror-polished, and then rolled at right angles (a surface perpendicular to the plate surface ) was measured using a micro Vickers hardness tester (FM-110, manufactured by Futuretech) under the measurement conditions of a test load of 10 gf (0.098 N) and a holding time of 10 seconds.

In addition, in order to accurately measure the hardness of the portion near the plate surface at 1/16 position from the plate surface, in the present invention, when the plate thickness is thin, approximately 1/16 or more of the thickness from the surface Hardness (Hv) may be measured from a distant position.

A method for obtaining the slopes B1 and B2 will be described. Of the plots of the hardness distribution obtained when obtaining the slope A, from the plot of the hardness distribution from the position 5 of the plate thickness 1/4 depth to the plate surface position 4, the 1/4 depth of the plate thickness The relationship between the hardness (Hv) from the thickness position 5 to the plate surface position 4 and the distance (mm) from the position half the thickness of the plate is approximated by a linear function, and the slope B1 of the linear function is obtained by the method of least squares. In addition, among the plots of the hardness distribution obtained when obtaining the slope A, the plot of the hardness distribution from the position 3 at a depth of 1/2 of the plate thickness to the position 5 at a depth of 1/4 of the plate thickness From this, the hardness (Hv) between position 3 at 1/2 depth of the plate and position 5 at 1/4 depth of plate thickness and the distance from the position at 1/2 depth of plate thickness (mm ) is approximated by a linear function, and the slope B2 of the linear function is obtained by the method of least squares.

In the aluminum alloy plate for molding of the present invention, the hardness distribution from the position of 1/2 depth of the plate thickness obtained as described above to the plate surface position is plotted, 1/2 depth of plate thickness The linear The value obtained by multiplying the value of the slope A of the function by the plate thickness (mm) (slope A x plate thickness (mm)) is 10 to 28, preferably 10 to 20, and particularly preferably 12 to 17. When the value of inclination A×plate thickness (mm) is within the above range, the amount of reduction in the amount of springback due to the final push is increased, and the shape fixability is excellent. On the other hand, if the value of inclination A×plate thickness (mm) is less than the above range, the amount of reduction in the amount of springback due to the final push is small, resulting in poor shape fixability. In addition, in order to increase the slope A, it is necessary to incorporate a large amount of work hardening. , either excessively large work hardening is required, or the plate thickness needs to be excessively increased. If the plate thickness is too large, it becomes difficult to create a distribution of hardness in the aluminum alloy plate for molding of the present invention in the plate thickness direction.

In the present invention, the "minimum two A linear function having a slope A of the linear function that approximates the relationship between the hardness (Hv) obtained by multiplication and the distance (mm) from the position at the half depth of the plate thickness by a linear function ", and the plate thickness The correlation coefficient (R ² ) with the plot of the hardness distribution from the half depth position to the plate surface position is 0.50 or more, preferably 0.70 or more, and particularly preferably 0.80 or more is.

In the aluminum alloy plate for molding of the present invention, the depth of 1/4 of the plate thickness is based on the plot of the hardness distribution from the position of 1/2 depth of the plate thickness to the plate surface position obtained as described above. From the plot of the hardness distribution from the position to the plate surface, the "hardness (Hv) obtained by the least squares method and 1/ 2 The slope B1 of the linear function, which approximates the relationship of the distance (mm) from the depth position by a linear function, and the position of 1/4 of the plate thickness from the position of 1/2 of the plate thickness From the plot of the hardness distribution up to, the "hardness (Hv) obtained by the least squares method and the thickness The absolute value of the difference (B1-B2) from the slope B2 of the linear function, which approximates the relationship of the distance (mm) from the position of 1/2 depth of the linear function, is preferably 10 or less, particularly preferably is 8 or less. The value of the difference between the slope B1 and the slope B2 based on the plot of the hardness distribution from the half depth position of the plate thickness of the aluminum alloy plate for forming to the plate surface position is determined by being in the above range. It is possible to improve the effect of reducing the amount of springback caused by pushing.

In the present invention, the hardness is measured at intervals of 1/16 of the plate thickness in the plate thickness direction. When the area is divided from the position of 2 depths to the position of 1/4 of the plate thickness, hardness is measured at intervals of 1/16th of the thickness. This is because an approximate linear function can be drawn, and the reliability of the slope value of the linear function increases. On the other hand, for example, if the hardness is measured at intervals of 1/10 of the plate thickness in the plate thickness direction, it is difficult to measure the hardness near the outermost surface. , and the value of the slope of the linear function becomes less reliable.

The plate thickness of the aluminum alloy plate for molding of the present invention is 0.4 to 5.0 mm, preferably 0.8 to 2.7 mm. In an aluminum alloy plate having a thickness less than or exceeding the above range, the value of "tilt A x plate thickness (mm)" is 10 to 28, preferably 10 to 20, particularly preferably 12 to 17. It is difficult to make a distribution of

The basic components of the aluminum alloy sheet for molding of the present invention are not particularly limited. various aluminum alloys such as the 7000 series.

The aluminum alloy sheet for molding of the present invention is preferably made of a JIS5000 series aluminum alloy or a JIS6000 series aluminum alloy.

The composition of the JIS5000 series aluminum alloy is Si: 0.25% by mass or less, Fe: 0.40% by mass or less, Cu: 0.10% by mass or less, Mn: 0.10% by mass or less, Mg: 2.20. 2.80% by mass, Cr: 0.15 to 0.35% by mass, Zn: 0.10% by mass or less, and the balance being aluminum and unavoidable impurities.

The chemical composition of the JIS6000 series aluminum alloy is Si: 0.20 to 0.60% by mass, Fe: 0.35% by mass or less, Cu: 0.10% by mass or less, Mn: 0.10% by mass or less, Mg: 0.45 to 0.90% by mass, Cr: 0.10% by mass or less, Zn: 0.10% by mass or less, Ti: 0.10% by mass or less, and the balance being made of an alloy containing aluminum and unavoidable impurities is more preferred.

The aluminum alloy sheet for molding of the present invention preferably has a tensile strength of 140.0 MPa or more, more preferably 150.0 to 300.0 MPa, and particularly preferably 160.0 to 290.0 MPa. The aluminum alloy plate for molding of the present invention has a value of "tilt A x plate thickness (mm)" of 10 to 28, preferably 10 to 20, particularly preferably 12 to 17, and more preferably " The absolute value of "slope B1 - slope B2" is preferably 10 or less, particularly preferably 8 or less, so that the tensile strength is preferably 140.0 MPa or more, more preferably 150.0 to 300.0 MPa, particularly preferably Although it has a high strength of 160.0 to 290.0 MPa, the amount of reduction in the amount of springback due to the final push is large, and the shape freezeability is excellent.

Example B, which is a plot of hardness distribution shown in FIG. After setting the plate thickness to 0.81 mm, solution treatment and artificial aging treatment were performed, and after artificial aging, 3.0% skin pass was performed. As shown in FIG. 3, in the plot of the hardness distribution of Example B, the hardness is the lowest at the central portion of the plate thickness (the position at the depth of 1/2 of the plate thickness), and the hardness is linearly increased to the plate surface. is changing. The slope A obtained by the method of least squares is 16 based on the hardness distribution plotted in FIG. Therefore, the value of "tilt A x plate thickness (mm)" is 13 (16 x 0.81). Then, the aluminum alloy plate of Example B was subjected to a 90-degree bending test at 20 kgf (196) N, 100 kgf (980) N, and 200 kgf (1961 N). 7° and 3.7°. The amount of springback is determined by the difference from 90°, and in the aluminum alloy plate of Example B, the phenomenon that the amount of springback is reduced under the condition of a large load in the 90° bending test, that is, the condition corresponding to the so-called final push. confirmed.

Comparative Example H, which is a plot of the hardness distribution shown in FIG. After setting the plate thickness to 0.82 mm, 3.0% skin pass was performed, followed by solution treatment and then artificial aging treatment. As shown in FIG. 9, in the plot of the hardness distribution of Comparative Example H, the slope A obtained by the method of least squares is 4.9. Therefore, the value of "tilt A x plate thickness (mm)" is 4.0 (4.9 x 0.82). When the 90-degree bending test was performed on the aluminum alloy plate of Comparative Example H at 20 kgf, 100 kgf and 200 kgf, the springback amounts were 8.7°, 10.3° and 8.0°, respectively. In the aluminum alloy plate of Comparative Example H, the amount of springback did not change even under the condition of a large load in the 90° bending test, that is, the condition corresponding to the so-called final push.

The aluminum alloy plate for molding of the present invention has a value of "tilt A x plate thickness (mm)" of 10 to 28, preferably 10 to 20, and particularly preferably 12 to 17, which corresponds to the decisive condition. It has excellent moldability in a high load 90° bending test. In general, a hard material is strongly influenced by springback, so it is difficult to realize a material having high strength and excellent formability. In such a technical background, in the aluminum alloy plate for molding of the present invention, a region with low hardness is created in the plate thickness direction, and the change in hardness in the plate thickness direction is calculated as "tilt A x plate thickness (mm) ” is controlled to satisfy 10 to 28, preferably 10 to 20, and particularly preferably 12 to 17, so that the in-plane stress of the plate material is changed by decisive pushing to reduce the amount of springback. Therefore, it has high strength and excellent shape fixability.

The aluminum alloy sheet for molding of the present invention is suitably produced by the method for producing an aluminum alloy plate for molding according to the first aspect of the present invention or the method for producing an aluminum alloy plate for molding according to the second aspect of the present invention described below. manufactured.

A method for producing an aluminum alloy sheet for molding according to the first embodiment of the present invention is a method for producing an aluminum alloy sheet for molding made of a JIS 5000 series aluminum alloy, and includes (1a) a cold work rate of 70.0% or more; (2a) Performing a skin pass with a rolling reduction of 1.0 to 10.0% after the stabilization treatment, (3a) Three passes with a rolling reduction of 20.0% or less per pass of cold working A method for producing an aluminum alloy sheet for molding, characterized by performing at least one of the above and (4a) treating with a leveler after the stabilization treatment.

In the method for producing an aluminum alloy plate for molding according to the first aspect of the present invention, there is provided a casting step of casting an aluminum alloy ingot having a composition of a JIS 5000 series aluminum alloy, a homogenization treatment, a hot rolling, and a cold rolling. Rolling and stabilization treatment are performed in order. In addition, in the manufacturing method of the aluminum alloy sheet for molding according to the first embodiment of the present invention, the casting method, the homogenization treatment method, and the stabilization treatment method are not particularly limited, and can be appropriately selected.

In the method for producing an aluminum alloy sheet for molding according to the first aspect of the present invention, (1a) the cold working ratio is set to 70.0% or more, and (2a) the reduction ratio after the stabilization treatment is 1.0 to 1.0%. 10.0% skin pass, (3a) performing 3 or more passes with a rolling reduction of 20.0% or less per pass of cold working, and (4a) treatment with a leveler after stabilization treatment. By performing at least one of the above steps, it is possible to increase the working and progress work hardening in the plate thickness direction, and to develop the hardness distribution in the aluminum alloy plate for molding of the present invention. . Any one of the above (1a) to (4a) may be implemented, or two or more of the above (1a) to (4a) may be implemented in combination. In the method of manufacturing an aluminum alloy sheet for molding according to the first aspect of the present invention, the value of the slope A can be easily increased by combining two or more of the above (1a) to (4a).

(1a) is to set the cold working rate to 70.0% or more, preferably 70.0 to 80.0% in the cold working. The cold working rate is the total working rate in cold working, and "cold working rate (%) = ((thickness before the first pass of cold working - after the last pass of cold working thickness)/plate thickness before the first pass of cold working)×100”.

(2a) is to perform skin pass with a rolling reduction of 1.0 to 10.0%, preferably 3.0 to 10.0% after the stabilization treatment. The skin pass is a rolling reduction calculated by "rolling reduction (%) = ((board thickness before skin pass - board thickness after skin pass) / board thickness before skin pass) x 100" is 1.0 to 10.0. %, preferably within the range of 3.0 to 10.0%. In the method for producing an aluminum alloy sheet for molding according to the first aspect of the present invention, the skin pass defined in (2a) is performed so that the cold working rate in cold working (total cold working rate in cold working) is 30.0 or more. It is preferably carried out when it is less than 70.0%, particularly when it is 30.0 to 60.0%.

(3a) is to perform three or more passes with a rolling reduction of 25.0% or less per pass of cold working. The rolling reduction per pass of cold working is calculated by "rolling reduction (%) = ((plate thickness before pass - plate thickness after pass) / plate thickness before pass) x 100". is. In the method for producing an aluminum alloy sheet for molding according to the first aspect of the present invention, it is preferable to perform three or more passes of cold working with a rolling reduction of 10.0 to 25.0% per pass. It is more preferable to perform 4 or more passes of cold working with a rolling reduction of 10.0 to 20.0% per pass, and cold working with a rolling reduction of 10.0 to 15.0% per pass. It is particularly preferable to perform the pass of 6 times or more. In the method for producing an aluminum alloy sheet for forming according to the first aspect of the present invention, the cold working path defined in (3a) is set so that the cold working rate in cold working (total cold working rate in cold working) is When it is 30.0 or more and less than 70.0%, it is preferable to carry out when it is particularly 30.0 to 60.0%.

(4a) is to treat with a leveler after stabilization treatment. A leveler is a device commonly used for the purpose of straightening the warp of a thin plate, and processing with a leveler is at least two stages provided so that the points of action of the rolls are slightly different from each other with respect to the traveling direction of the plate. A process in which the board is passed between rolls of 100 lbs and given at least two bends in opposite directions. In the method for producing an aluminum alloy sheet for forming according to the first embodiment of the present invention, the treatment with a leveler specified in (4a) is performed so that the cold working rate in cold working (total cold working rate in cold working) is 30. When it is 0 or more and less than 70.0%, it is preferable to carry out when it is particularly 30.0 to 60.0%.

A method for producing an aluminum alloy sheet for molding according to a second embodiment of the present invention is a method for producing an aluminum alloy sheet for molding made of a JIS 6000 series aluminum alloy, and (1b) the cold working ratio is set to 70.0% or more. (2b) skin pass with a rolling reduction of 1.0 to 10.0% after artificial aging treatment; (3b) three passes with a rolling reduction of 20.0% or less per pass of cold working. and (4b) treatment with a leveler after solution treatment or artificial aging treatment.

In the method for producing an aluminum alloy plate for molding according to the second aspect of the present invention, there is provided a casting step of casting an aluminum alloy ingot having a composition of a JIS6000 series aluminum alloy, a homogenization treatment, a hot rolling, and a cold rolling. Rolling, solution treatment, and artificial aging treatment are performed in order. In addition, in the method of manufacturing the aluminum alloy sheet for molding according to the second aspect of the present invention, the casting method, homogenization treatment method, solution treatment method, and artificial aging treatment method are not particularly limited and may be appropriately selected.

In the method for producing an aluminum alloy sheet for molding according to the second embodiment of the present invention, (1b) the cold working ratio is set to 70.0% or more, and (2b) the reduction ratio after the artificial aging treatment is 1.0 to 1.0%. 10.0% skin pass, (3b) three or more cold working passes with a rolling reduction of 20.0% or less per pass, and (4b) treatment with a leveler after artificial aging treatment. By performing at least one of the above steps, it is possible to increase the working and progress work hardening in the plate thickness direction, and to develop the hardness distribution in the aluminum alloy plate for molding of the present invention. . Any one of the above (1b) to (4b) may be implemented, or two or more of the above (1b) to (4b) may be implemented in combination. In the method of manufacturing an aluminum alloy sheet for forming according to the second aspect of the present invention, the value of the slope A can be easily increased by combining two or more of the above (1b) to (4b).

(1b) is to set the cold working rate to 70.0% or more, preferably 70.0 to 80.0% in the cold working. The cold working rate is the total working rate in cold working, and "cold working rate (%) = ((thickness before the first pass of cold working - after the last pass of cold working thickness)/plate thickness before the first pass of cold working)×100”.

(2b) is to perform skin pass with a rolling reduction of 1.0 to 10.0%, preferably 3.0 to 10.0% after the artificial aging treatment. The skin pass is a rolling reduction calculated by "rolling reduction (%) = ((board thickness before skin pass - board thickness after skin pass) / board thickness before skin pass) x 100" is 1.0 to 10.0. %, preferably within the range of 3.0 to 10.0%. In the method for producing an aluminum alloy sheet for forming according to the second aspect of the present invention, the skin pass defined in (2b) is performed so that the cold working rate in cold working (total cold working rate in cold working) is 30.0 or more. It is preferably carried out when it is less than 70.0%, particularly when it is 30.0 to 60.0%.

(3b) is to perform 3 or more passes with a rolling reduction of 25.0% or less per pass of cold working. The rolling reduction per pass of cold working is calculated by "rolling reduction (%) = ((plate thickness before pass - plate thickness after pass) / plate thickness before pass) x 100". is. In the method for producing an aluminum alloy sheet for molding according to the second aspect of the present invention, it is preferable to perform cold working passes with a rolling reduction of 10.0 to 25.0% for three times or more. It is more preferable to perform 4 or more passes of cold working with a rolling reduction of 10.0 to 20.0% per pass, and cold working with a rolling reduction of 10.0 to 15.0% per pass. It is particularly preferable to perform the pass of 5 times or more. In the method for producing an aluminum alloy sheet for forming according to the second aspect of the present invention, the cold working path defined in (3b) is set so that the cold working rate in cold working (total cold working rate in cold working) is When it is 30.0 or more and less than 70.0%, it is preferable to carry out when it is particularly 30.0 to 60.0%.

(4a) is treatment with a leveler after solution treatment or after artificial aging treatment. A leveler is a device commonly used for the purpose of straightening the warp of a thin plate, and processing with a leveler is at least two stages provided so that the points of action of the rolls are slightly different from each other with respect to the traveling direction of the plate. A process in which the board is passed between rolls of 100 lbs and given at least two bends in opposite directions. In the method of manufacturing an aluminum alloy sheet for forming according to the second aspect of the present invention, the treatment with a leveler specified in (4b) is performed so that the cold working rate in cold working (total cold working rate in cold working) is 30. When it is 0 or more and less than 70.0%, it is preferable to carry out when it is particularly 30.0 to 60.0%.

In the method for producing an aluminum alloy plate for forming according to the first aspect of the present invention or the method for producing an aluminum alloy plate for forming according to the second aspect of the present invention, the hardness as described above in the aluminum alloy plate for forming according to the present invention The reason why the distribution appears is as follows.
It is considered that the hardness distribution in the aluminum alloy sheet for molding of the present invention originates from work hardening. In metals, dislocations increase due to working stress, and internal stress accumulates. Work hardening is said to occur when the number of dislocations increases too much, causing the dislocations to become entangled or cut, resulting in hardening of the material itself. In large-scale deformation such as hot rolling, the stress is uniformly distributed throughout the plate thickness, so there is no hardness distribution in the plate thickness direction. On the other hand, in the cold rolling or skin pass of (1a) to (3a) and (1b) to (3b), compared to hot rolling, due to small-scale deformation, work hardening is likely to occur in and around the surface layer. , it is possible to create a hardness distribution that satisfies the requirements relating to the aluminum alloy sheet for molding of the present invention in the plate thickness direction. This is also evident in Examples AF. In addition, from the above principle, even in the method of bending the plate for the purpose of forcing the warp of the plate, such as the leveler of (4a) and (4b), the plate surface layer is work hardened, It is possible to create a hardness distribution that satisfies the regulations relating to the aluminum alloy sheet for molding of the present invention. This is also evident in Example G.

The effect of reducing the amount of springback in the aluminum alloy plate for molding of the present invention is derived from the hardness distribution in the plate thickness direction derived from work hardening, so not only work hardening alloys such as JIS 5000 series but also JIS 6000 series A similar tendency is obtained in such a heat treatable alloy. In heat-treated alloys, a large number of precipitates are formed before and after artificial aging, which affects the hardness of the alloy. However, since the hardness distribution in the sheet thickness direction of the aluminum alloy sheet for molding of the present invention is derived from work hardening due to cold rolling, skin pass, etc., it is believed that there is no effect on the inclination of the hardness distribution itself before and after aging. think. This is also evident in Examples AG.

Springback is mainly due to elastic deformation during bending of the material. Since the elastic deformation region becomes narrower as the strength of the material decreases, the amount of springback decreases as the strength of the material decreases. In the aluminum alloy sheet for molding of the present invention, a soft layer exists in the central portion of the plate thickness, and the elastic deformation region of that portion is narrow, so that the effect of reducing the amount of springback can be improved as a result. In other words, the wider the soft layer exists in the sheet thickness direction, the more the layer is plastically deformed.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples shown below.

(Example 1)
JIS A6063 aluminum alloy and JIS 5052 aluminum alloy were cast by DC casting. Next, for JIS A6063 aluminum alloy, homogenization treatment, hot rolling, cold rolling, solution treatment, and artificial aging treatment are performed in order, and for JIS 5052 aluminum alloy aluminum alloy, homogenization treatment and hot rolling are performed. , cold rolling, and stabilization treatment are performed in order, and in these processes, the manufacturing conditions shown in Table 1 or Table 2 are performed, and in the JIS A6063 aluminum alloy, the plate shown in Table 1 is produced with a target of 0.80 mm. With a target thickness of 2.70 mm for JIS 5052 aluminum alloy, aluminum alloy plates having thicknesses shown in Table 2 were produced. General conditions were used for the homogenization treatment, solution treatment, artificial aging treatment, and stabilization treatment.
Differences from the standard plate under each condition are as follows. Example A: The rate of cold working was increased. Example B: After the artificial aging treatment, skin pass was performed with a rolling reduction of 3.0%. Example C: The number of cold working passes was increased. Example D: The number of cold working passes was increased, and a skin pass was performed with a rolling reduction of 3.0% after the artificial aging treatment. Example E: After the artificial aging treatment, a skin pass was performed with a rolling reduction of 5.0%. Example F: After the artificial aging treatment, a skin pass was performed with a rolling reduction of 10.0%. Example G: Treatment with a leveler was performed after solution treatment. Comparative Example H: After cold rolling and before solution heat treatment, skin pass was performed with a rolling reduction of 3.0%. Comparative Example I: The number of cold working passes was reduced. Example J: Increased cold rolling rate. Example K: The number of cold working passes was increased. Example L: Skin pass was performed with a rolling reduction of 3.0% after the stabilization treatment.

Each evaluation method and evaluation criteria are as follows.
<Hardness (Hv) measurement>
The hardness (Hv) was measured according to JIS Z 2244. An aluminum alloy plate is embedded in resin, mirror-polished, and then a rolled right-angled cross section (surface perpendicular to the plate surface) is subjected to a test load of 10 gf using a micro Vickers hardness tester (FM-110, manufactured by Futuretech Co., Ltd.). (0.098 N) and the hardness (Hv) was measured under the measurement conditions of 10 seconds of holding time. The measurement was performed at predetermined intervals in the thickness direction, three points were measured for each measurement position, and the average value was defined as the hardness (Hv) at that position.
The thickness direction of the JIS6000 series aluminum alloy plate was measured at intervals of 0.05 mm, and the thickness direction of the JIS5000 series aluminum alloy plate was measured at intervals of 0.168 mm.
At the position of the outermost layer, the hardness was not measured because the impression of Vickers hardness also reached the resin.
The results are shown in Tables 3 and 4. Further, each hardness distribution is shown in FIGS. 2 to 15. FIG. Table 5 shows the slope A obtained by the method of least squares.

<Springback amount (formability)>
In order to evaluate the formability, five plates each having a size of 60 mm in the rolling direction and 30 mm in the width direction were prepared and subjected to a 90° bending test with a bending radius R of 5.0 mm. The test loads were 20 kgf (196 N), 100 kgf (980 N), and 200 kgf (1961 N). After the load was removed, the angle of the plate was determined using a protractor, and the difference from 90° was taken as the amount of springback. The amount of springback was taken as the average value of 5 sheets.

Each evaluation result is shown in Table 5. If the reduction in the amount of springback at 200 kgf compared to 20 kgf was 1° or more, it was evaluated as "good" because it was excellent in formability. It was set as "evaluation: bad" because it is inferior.

From Table 5, when the value obtained by multiplying the slope A of the approximate linear function by the plate thickness (mm) (slope A × plate thickness (mm)) based on the hardness distribution shown in FIGS. 2 to 15 is 10 or more In addition, it was found that the amount of springback at 200 kgf was reduced by 1° or more compared to that at 20 kgf.

In addition, when the manufacturing conditions were A, B, C, D, E, F, G, J, K, and L, the “slope A×thickness (mm)” was 10 or more. On the other hand, when the manufacturing conditions are H and I, the slope of the hardness distribution in the plate thickness direction is too small, so the "slope A x plate thickness (mm)" is less than 10, resulting in springback. It is assumed that the amount did not decrease.

The aluminum alloy plate of the present invention has a small amount of springback after forming, and good formability can be obtained.

1 Aluminum alloy plate for forming 3 Half thickness position 4 Plate surface position 5 Plate thickness position 1/4 depth 6 Plate thickness direction 7 Plate surface p Plate thickness q Half thickness Length r 1/4 of plate thickness

Claims (7)

The hardness (Hv) is measured from the position of 1/2 of the plate thickness to the plate surface at intervals of 1/16 of the plate thickness in the plate thickness direction, the vertical axis is the hardness (Hv), and the horizontal axis As the distance (mm) from the position of 1/2 depth of the plate thickness, plot the hardness distribution, and from the plot of the hardness distribution, the hardness (Hv) and 1/2 depth of the plate thickness When the relationship of the distance (mm) from the position is approximated by a linear function, and the slope A of the linear function is obtained by the method of least squares, the value obtained by multiplying the slope A by the plate thickness (mm) is 10 to 28. An aluminum alloy plate for molding, characterized by: Among the plots of the hardness distribution, from the plot of the hardness distribution from the position of 1/4 depth of the plate thickness to the plate surface, the hardness (Hv) and the position of 1/2 depth of the plate thickness The relationship of the distance (mm) is approximated by a linear function, the slope B1 of the linear function is obtained by the method of least squares, and from the plot of the hardness distribution, from the position half the thickness of the plate From the plot of the hardness distribution up to 1/4 of the plate thickness, the relationship between the hardness (Hv) and the distance (mm) from the position of 1/2 of the plate thickness is approximated by a linear function. 2. The molding according to claim 1, wherein the absolute value of the difference (B1-B2) between the slope B1 and the slope B2 is 10 or less when the slope B2 of the linear function is obtained by the method of least squares. Aluminum alloy plate. 3. The aluminum alloy sheet for molding according to claim 1, wherein the tensile strength is 140.0 MPa or more. 4. The aluminum alloy sheet for molding according to any one of claims 1 to 3, characterized by being made of a JIS5000 series aluminum alloy. 4. The aluminum alloy sheet for molding according to any one of claims 1 to 3, characterized by being made of a JIS6000 series aluminum alloy. A method for manufacturing an aluminum alloy sheet for molding made of a JIS 5000 series aluminum alloy, comprising: (1a) a cold working ratio of 70.0% or more; and (2a) a reduction ratio of 1.0 to 10.0 after stabilization treatment (3a) performing three or more passes with a rolling reduction of 25.0% or less per pass of cold working, and (4a) treating with a leveler after stabilization treatment. A method for producing an aluminum alloy sheet for molding, characterized by carrying out at least one of the above. A method for producing an aluminum alloy sheet for molding made of a JIS 6000 series aluminum alloy, comprising: (1b) a cold working rate of 70.0% or more; and (2b) a reduction rate of 1.0 to 10.0 after artificial aging treatment. (3b) performing three or more passes with a rolling reduction of 25.0% or less per pass of cold working, and (4b) leveling after solution treatment or after artificial aging treatment A method for producing an aluminum alloy plate for molding, characterized in that at least one of the treatments is performed with.

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