JP2010121164A - Aluminum alloy sheet having excellent moldability, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an aluminum alloy sheet which has high elongation and has excellent moldability in both of bulging properties and drawability so as to be applied to wide applications such as an electronic component case and an automotive member. <P>SOLUTION: The molten metal of an aluminum alloy having a componential composition including, by mass, 1.0 to 2.0% Fe, and the balance aluminum with inevitable impurities, and in which the content of Ti as the inevitable impurities is limited to ≤0.01% is subjected to DC casting while being electromagnetically stirred, and the obtained ingot is subjected to homogenizing heat treatment, rolling and final annealing so as to obtain an aluminum alloy sheet having a structure where the average crystal grain size is controlled to ≤20 μm, and the area ratio of the crystals in the ä110} orientation is controlled to ≥25%. By controlling the structure of the aluminum alloy sheet to the above, all of an elongation of ≥35%, the average r value of ≥0.85, a ball head bulging height of ≥33 mm and a limit drawing ratio of ≥2.17 can be attained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an aluminum alloy plate having high elongation and excellent formability of both stretchability and drawability, and a method for producing the same.

In recent years, for the purpose of reducing the weight of electronic devices and automobiles, aluminum alloy plates have been used in place of steel plates in cases of electronic devices and automobile members. However, since many of them have complicated shapes, excellent formability is required for aluminum alloy sheets for such applications.
In addition to bending forming for the above-mentioned applications, bulging forming, drawing forming, and a combination thereof are used as a method for forming an aluminum alloy plate. In order to meet this requirement, Patent Document 1 proposes an aluminum alloy plate excellent in stretchability having a total elongation of 40% or more and a local elongation of 10% or more.
In Patent Document 2, the difference between the tensile strength and 0.2% proof stress is 103 MPa or more, the Erichsen value is 9.5 or more, the diameter is 50 mm, the shoulder radius is 5 mm, and the limit drawing ratio in the cylindrical deep drawing test is 2.05 or more. An aluminum alloy plate excellent in press formability has been proposed.
JP 2001-288523 A JP 2001-342577 A

  However, although the aluminum alloy plate proposed in Patent Document 1 is excellent in elongation and stretch formability, the drawability is not sufficient, while the aluminum alloy sheet proposed in Patent Document 2 still has the stretch formability. In addition to the shortage, it is necessary to provide an alkali-soluble lubricating film mainly composed of a polyurethane composition and a lubricating function-imparting agent.

  The present invention has been devised to solve such a problem. By using various molding methods, the present invention has high elongation and can be applied to a wide range of applications such as electronic device cases and automobile parts. Aluminum alloy sheet with excellent formability for both extrudability and drawability, specifically high elongation of 35% or more, average r value (Rankford value) of 0.85 or more, ball head overhang height of 33mm or more, Another object of the present invention is to provide an aluminum alloy sheet excellent in formability having a limit drawing ratio of 2.17 or more.

In order to achieve the object, the aluminum alloy plate having excellent formability according to the present invention contains Fe in an amount of 1.0 to 2.0 mass%, the balance is made of aluminum and inevitable impurities, and Ti as the inevitable impurities is 0.01 mass% or less. And a structure in which the average crystal grain size is 20 μm or less and the area ratio of {110} oriented crystals is adjusted to 25% or more.
The aluminum alloy plate excellent in formability of the present invention may further have a component composition containing 2.0% by mass or less of Mn.

The aluminum alloy sheet having excellent formability according to the present invention is obtained by DC casting an aluminum alloy melt having the above component composition while electromagnetically stirring, and homogenizing heat treatment, rolling, and final annealing of the resulting ingot. Manufactured.
The electromagnetic stirring is preferably performed with a magnetomotive force of 15000 to 25000 At and a frequency of 10 to 30 Hz.
Moreover, as said final annealing, it is preferable to perform the batch annealing process for 1 to 10 hours at 350-500 degreeC, or the continuous annealing process for 1 second-10 minutes at 400-550 degreeC.

The aluminum alloy sheet provided by the present invention has a specified composition and is composed of fine crystal grains and has a uniform crystal orientation. It has excellent moldability. For this reason, it can be molded and used in a case of an electronic device having a complicated shape or a member of an automobile without the need for a lubricating coating.
In addition, according to the method for producing an aluminum alloy plate of the present invention, an aluminum alloy plate having a high elongation and excellent in stretchability and drawability can be obtained at a low cost.

When an aluminum alloy plate is to be used in a wide range of applications such as electronic equipment cases and automotive parts by the stretch forming method or deep drawing method, the aluminum alloy plate has a high elongation and has a high stretchability and drawability. Therefore, a material excellent in both formability is required.
The present inventors have also intensively studied in order to obtain an aluminum alloy plate having high elongation and excellent formability in both stretchability and drawability.
In the process, by reducing the average crystal grain size and increasing the area ratio occupied by {110} oriented crystals, it is possible to obtain an aluminum alloy sheet with high elongation and excellent stretch-formability and drawability. I found.

The present invention has been made on the basis of this finding, DC casting while stirring the aluminum alloy molten metal of a specific chemical component, by homogenizing heat treatment, rolling process, and final annealing the obtained ingot, The present invention was completed by investigating that the average crystal grain size was refined and the area of {110} oriented crystals was high.
That is, the present invention adjusts to a component composition in which Fe is 1.0 to 2.0% by mass, the balance is aluminum and inevitable impurities, and Ti as the inevitable impurities is 0.01% by mass or less, preferably 0.005% by mass or less. By adjusting to a structure in which the average grain size is 20 μm or less and the area ratio of {110} oriented crystals is 25% or more, the stretchability and drawability can be improved. By satisfying the above requirements, specifically, a high elongation of 35% or more, an average r value of 0.85 or more, a ball head overhang height of 33 mm or more, and a limit drawing ratio of 2.17 or more can be achieved. Is obtained.
Furthermore, you may contain 2.0 mass% or less Mn.

  The aluminum alloy sheet according to the present invention is obtained by DC casting the molten aluminum alloy having the above composition while electromagnetically stirring, and homogenizing heat treatment, rolling, and final annealing of the obtained ingot. That is, by DC casting while stirring magnetically, the dendritic portion of the dendritic crystal generated during solidification of the molten metal is divided by the electromagnetic stirring force, and the divided dendritic portion is dispersed in the molten metal to form crystal nuclei, Increasing the number of crystal nuclei to obtain an aluminum alloy ingot with a refined and uniform crystal grain size, and in addition to the obtained ingot, homogenized heat treatment, rolling, and final annealing, As a result, the crystal grain size of the aluminum alloy plate was refined and the area ratio of {110} oriented crystals was increased, thereby improving the formability.

  The conditions of electromagnetic stirring during casting vary depending on the cross-sectional area of the ingot, but when the ingot is 400 to 600 mm thick and 800 to 1600 mm wide, the magnetomotive force is 15000 to 25000 At and the frequency is 10 to 30 Hz. It is preferable. Further, the final annealing treatment after rolling is a batch annealing treatment of holding at 350 to 500 ° C. for 1 to 10 hours or a continuous annealing treatment of holding at 400 to 550 ° C. for 1 second to 10 minutes. As a result, an aluminum alloy plate having an average crystal grain size of 20 μm or less and an area ratio of {110} oriented crystals of 25% or more can be easily obtained.

By the way, in the case of steel, by casting with electromagnetic stirring, the dendritic portion of the dendritic crystal generated during solidification of the molten metal is divided by this electromagnetic stirring force, and the crystal grain size is refined to improve the moldability. However, according to the study by the present inventors, in the case of an aluminum alloy, the crystal grain size of the aluminum alloy ingot is simply reduced. The formability of the aluminum alloy plate is not improved.
In the case of an aluminum alloy, the present invention separates the dendritic portion of the dendritic crystal generated during solidification of the molten metal by this electromagnetic stirring force by casting with electromagnetic stirring, and further combines the final annealing treatment after rolling. In addition to reducing the average crystal grain size of the aluminum alloy plate and increasing the area of the {110} -oriented crystal, the formability is improved. It was not converted to an alloy.

Japanese Patent Laid-Open No. 11-285793 discloses a technique for continuously casting an aluminum alloy containing 0.75 to 2.0% by mass of Fe with electromagnetic stirring to obtain a cast material for thixocasting by crushing and refining acicular intermetallic compounds. It is disclosed in the publication.
On the other hand, in the aluminum alloy of the present invention, the contents of Si, Cu, and Ti are reduced to unavoidable impurity levels, respectively, so that the primary crystal upon solidification is Al. The present invention divides the dendritic portion of primary Al dendritic crystals by electromagnetic stirring force, and further combines the final annealing treatment after rolling to refine the average crystal grain size of the aluminum alloy sheet, and {110} An aluminum alloy plate excellent in formability is obtained by increasing the area of the orientation crystal, which is different from the basic idea introduced in the patent document.

  Similarly, an aluminum alloy containing 0.75 to 1.5 mass% Fe and [Fe / 5 + 0.2] mass% or less, or 1.5 to 2.0 mass% Fe and [2.0−Fe] mass% or less Mn is electromagnetically treated. Japanese Patent Laid-Open No. 2000-637 discloses a technique for continuously casting while stirring and crushing and refining acicular intermetallic compounds, and further, 3 / 4-5 / 3 mass% Fe and [Fe / 5] A technique for continuously casting an aluminum alloy containing [2.0-Fe]% by mass of Mn with electromagnetic stirring to obtain a cast material for thixocasting obtained by crushing and refining acicular intermetallic compounds is disclosed in Japanese Patent Application Laid-Open No. 2000-15405. It is disclosed in the gazette. These techniques are also intended to crush and refine the acicular intermetallic compound, and are different from the basic idea of the present invention.

Next, the present invention will be described in detail.
First, the solidification process of the Al-Fe alloy according to the present invention will be described.
When the Al-Fe alloy according to the present invention is solidified, the crystal grows while diffusing Fe from the first solidified crystal portion into the molten metal, and the concentration of Fe in other crystals is around the growing crystal. The concentration is higher than that of the portion not involved in the growth. The high concentration portion has a lower solidification start temperature and a slower crystal growth rate. On the other hand, in the cooling process of solidification, the part that does not participate in the growth of the other crystals is more easily promoted to grow the crystal compared to the crystal part where the Fe concentration is high, and the diffusion of Fe into the molten metal is similar to the above. As described above, the crystal grows, and the growth rate is slowed by the influence of the Fe concentration as described above. By repeating such crystal growth, the crystal grows in a dendritic shape, and solidification is completed.
The present invention intends to effectively use the dendritic portion of the dendritic crystal as a crystal nucleus. The electromagnetic branching portion divides the dendritic portion into an appropriate size and disperses a large number of the divided dendritic portions in the molten metal. Thus, the crystal nuclei are used to refine and make uniform the crystal grain size of the ingot.

Next, the reason for specifying each invention specifying requirement will be described.
Fe: 1.0-2.0 mass%
Fe crystallizes out as an Al-Fe intermetallic compound. This intermetallic compound is effective in improving the strength of the aluminum alloy, and contributes to the effect of refining crystal grains as a recrystallization nucleus during final annealing. When Fe is less than 1.0% by mass, these effects are insufficient and the average crystal grain size exceeds 20 μm. On the other hand, when the amount exceeds 2.0% by mass, a large intermetallic compound of Al-Fe system crystallizes, and the recrystallized grains coarsen during final annealing, but the area ratio of {110} oriented crystals does not improve. , The moldability is reduced. Therefore, the Fe content is set to 1.0 to 2.0 mass%.

Mn: 2.0% by mass or less
When Mn is added to an aluminum alloy together with Fe, it crystallizes out as an Al-Fe-Mn intermetallic compound. This intermetallic compound, like the Al—Fe-based intermetallic compound, increases the effect of improving the strength of the aluminum alloy and contributes to the effect of refining crystal grains as a recrystallization nucleus during final annealing. Therefore, it is contained as necessary. However, if the amount of Mn added exceeds 2.0% by mass, the Al-Fe-Mn intermetallic compound becomes coarse, resulting in difficulty in plate making. Therefore, when Mn is added, the amount added is 2.0% by mass or less.

Inevitable impurities Conventionally, Ti is in the form of Al-Ti alloy, Al-Ti-B alloy, Al-Ti-C alloy, etc., and as a component of grain refiner of aluminum alloy ingot, feathery crystals and coarse It is added for the purpose of preventing the occurrence of crystals and preventing cracks during casting or plate cracks during rolling. This is because during casting of an aluminum alloy, particles such as TiB ₂ and TiC, which are compounds of Ti, B, and C, crystallize in the molten metal prior to solidification of the aluminum, which acts as a crystal nucleus in the solidification of the aluminum. To be understood. When the grain refiner for aluminum alloy ingots as described above exceeds 0.01% by mass as the Ti content, the effect of refinement becomes apparent.
However, according to the study by the present inventors, it was found that the effect of electromagnetic stirring is reduced when Ti is contained in the present invention. The details of the reason are unknown, but if the Ti content exceeds 0.01% by mass, particles such as TiB ₂ and TiC crystallize in the melt prior to solidification of the aluminum, and the dendritic crystals grow as described above. This is presumably because it crystallizes before it.
Therefore, in the present invention, when melting the alloy, various melting raw materials such as ingots, scraps and additive alloys are selected based on the respective Ti contents, and the amount of Ti inevitably mixed in the molten alloy is 0.01 mass. % To be less than or equal to%.

Si is a typical impurity that is inevitably mixed, but in the alloy of the present invention, up to 0.2 mass% is allowed. When Si exceeds 0.2% by mass, an Al-Fe-Si compound with low deformability is formed, and the moldability is lowered.
Further, Cu and Zn as inevitable impurities are allowed up to 0.1% by mass, but preferably 0.05% by mass or less.
Mn is basically an impurity, and is preferably 0.05% by mass or less. However, since it has a strengthening action as described above, 2.0% by mass may be included as the upper limit when this strengthening action is expected.
Other inevitable impurities are allowed up to 0.05% by mass.

Average crystal grain size: 20 μm or less When crystal grains become finer, the elongation increases and the stretchability improves, and the strength increases and the drawability improves. When the average crystal grain size exceeds 20 μm, the stretchability and squeezeability are lowered, the average r value is less than 0.85, and the limit squeeze ratio is less than 2.17. The average grain size is preferably 15 μm or less, more preferably 10 μm or less. When the average crystal grain size is 10 μm or less, the average r value is 0.95 or more and the limit drawing ratio is 2.20 or more.
In the present invention, the crystal grain size is measured by using SEM-EBSD to measure crystal grains in the range of 1 mm × 1 mm of the cross section of the aluminum alloy sheet including the rolling parallel direction, as shown in FIG. The boundary of small inclination of less than 15 ° is regarded as the sub-grain boundary within the crystal grain, while the region surrounded by the boundary of inclination of 15 ° or more is taken as the crystal grain, and the equivalent circle diameter of the crystal grain is measured. The average value is calculated.

{110} orientation crystal area ratio: 25% or more
The higher the area ratio of {110} oriented crystals, the higher the average r value of the aluminum alloy sheet, and the better the drawability.
In general, the area ratio of {110} orientation crystal is measured by analyzing the crystal grain of the cross section of the aluminum alloy plate including the rolling parallel direction with SEM-EBSD, and the area of the crystal grain within 10 ° from the {110} orientation It can be obtained by measuring the rate.
According to the study by the present inventors, from the {110} orientation obtained by analyzing the crystal grain of the cross section of the aluminum alloy plate including the rolling parallel direction shown in FIG. 1 as “crystal grain measurement cross section” by SEM-EBSD. As the area ratio of crystal grains within 10 ° is higher, the average r value of the aluminum alloy sheet is higher. Then, when the area ratio of the crystal grains within 10 ° from the {110} orientation obtained in this way is less than 25%, an average r value of 0.85 or more cannot be obtained, so that the {110 } Set the area ratio of orientation crystals to 25% or more.

Next, the manufacturing method of the aluminum alloy plate of this invention is demonstrated.
Casting method In the present invention, DC casting is performed with electromagnetic stirring. Here, DC casting refers to pouring molten metal introduced into the quenching mold whose inner wall surface is water-cooled, and cooling and solidifying the molten metal on the inner wall surface of the quenching mold. It is a casting method in which cooling is performed by drawing out cooling water onto the ingot and quenching, and the aluminum alloy casting method is known as having excellent productivity.
Further, a hot top DC casting is also known as a casting method of an aluminum alloy, in which a heat insulating hot water reservoir is provided at the upper part of the quenching mold, and the molten metal is introduced into the heat insulating hot water hot pot by casting. Such a casting method is also a category of DC casting, and can be suitably used in the practice of the present invention.

Electromagnetic stirring condition When the aluminum alloy melt is solidified, the crystal grows at a position where it is easy to solidify, that is, the crystal nucleus. Conventionally, as described above, an ingot crystal grain refining agent containing Ti is added and contained to form crystal nuclei. Therefore, if there are many crystal nuclei, the crystal grain of an ingot will become small. In the present invention, an ingot crystal grain refiner is refined to prevent casting cracks or rolling cracks without using the Ti-containing ingot crystal grain refining agent.
By the way, although DC casting uses a quenching mold as described above, solidification starts from the inner wall surface of the mold when the ingot crystal grain refining agent is not added. The crystal formed by solidification grows in a dendritic shape with the solidification start point as the root.If the dendritic portion of the dendritic crystal can be divided and dispersed in the molten metal, the divided dendritic portion is cast into the casting containing Ti. It can be used as a substitute for the crystal nuclei of the grain refiner of the lump, and if there are many parting points in the tree branch, the crystal grains of the ingot will be refined. The fine solidified structure is bent while gradually increasing, and the intermetallic compound produced in the final solidified portion is also finely and uniformly dispersed.

  The electromagnetic stirring of the present invention is for finely dividing the dendritic portion of the dendritic crystal grown on the inner wall surface of the mold and dispersing the divided dendritic portion in the molten metal to form a crystal nucleus. In the method, since the crystal nucleus grows while being stirred in the molten metal, the size of the crystal grain of the ingot is more likely to be uniform than when the grain refiner for the ingot containing Ti is used. When the ingot crystal grains become uniform in size, coupled with the subsequent homogenization heat treatment, rolling, and final annealing, as a result, the crystal grains of the aluminum alloy sheet become finer, and the area ratio of {110} oriented crystals becomes smaller. Increases the moldability.

  A preferable value of the electromagnetic stirring condition varies depending on the cross-sectional area of the ingot, but the magnetomotive force may be selected from a range of 1000 to 100,000 At and a frequency of 5 to 80 Hz. If the cross-sectional area is small, the magnetomotive force is small and the frequency is high, and if the cross-sectional area is large, the magnetomotive force is large and the frequency is low. In particular, when the ingot has a thickness of 400 to 600 mm and a width of 800 to 1600 mm, a magnetomotive force of 15000 to 25000 At and a frequency of 10 to 30 Hz are optimal.

  When the magnetomotive force or frequency is less than a preferable value that varies depending on the cross-sectional area of the ingot, the magnetic stirring force is weak, the effect of dividing the dendritic portion of the dendritic crystal generated in the molten metal cannot be obtained, and the ingot crystal Since the grain structure is not refined, the average crystal grain size of the aluminum alloy sheet does not become 20 μm or less as a result. On the other hand, if the magnetomotive force exceeds a preferable value that varies depending on the cross-sectional area of the ingot, the electromagnetic stirring force is too strong, the dendritic crystals are only broken at the root, and the number of crystal nuclei is not increased. The average grain size of the alloy plate does not decrease to 20 μm or less. Also, if the frequency exceeds a preferable value that varies depending on the cross-sectional area of the ingot, the electromagnetic force is concentrated on the portion in contact with the mold of the molten metal due to the skin effect and does not spread over the entire molten metal. The average grain size of the part where the force was not reduced does not decrease to 20 μm or less.

Homogenization heat treatment conditions Homogenization heat treatment is performed for the purpose of homogenizing the distribution of solute elements, fragmenting Al-Fe-Mn crystals, and precipitating Fe and Mn. The conditions may be known ones, and are sufficiently homogenized by holding at a temperature of 450 to 620 ° C. for 5 hours or longer as disclosed in, for example, JP-A-2002-348625.

Rolling conditions Hot rolling conditions are not particularly limited, but are preferably performed at a temperature of 350 ° C. or higher.
The cross-section reduction rate in cold rolling is in the range of 50 to 95%. When the cross-section reduction rate is less than 50%, the crystal grains after the final annealing become coarse, and elongation, stretchability and squeezability may deteriorate. If the cross-section reduction rate exceeds 95%, there is a risk of ear cracks occurring during rolling.
Intermediate annealing may be performed as necessary during the cold rolling. The intermediate annealing may be performed a plurality of times. In that case, it is preferable that the cross-sectional reduction rate after the last intermediate annealing is in the range of 50 to 95%. It is preferable that the cross-sectional reduction rate of the cold rolling until the intermediate annealing and the cross-sectional reduction rate of the cold rolling between the plurality of intermediate annealings are 95% or less. If the cross-section reduction rate exceeds 95%, there is a risk that ear cracks may occur during rolling.

Final annealing conditions
Batch annealing at 350 to 500 ° C. for 1 to 10 hours or continuous annealing at 400 to 550 ° C. for 1 second to 10 minutes is preferable.
At temperatures below 350 ° C or batch annealing for less than 1 hour, temperatures below 400 ° C or continuous annealing for less than 1 second, recrystallization is incomplete, resulting in large variations in the property values related to formability. I can't get it. Such a thing is not suitable for use in a case of an electronic device or a member of an automobile. In batch annealing at 500 ° C or higher or over 10 hours, and continuous annealing at 550 ° C or higher or 10 minutes or longer, the crystal grains become coarse, so the elongation cannot reach 35% and the average r value is less than 0.85 Moreover, the LDR (limit drawing ratio) is less than 2.17, and the desired stretchability and drawability cannot be obtained.
After annealing, distortion may be corrected with a tension leveler as necessary. The effect of the present invention is not impaired by distortion correction.

Example 1;
Next, specific examples will be described.
A molten aluminum alloy having the composition shown in Table 1 is melted, and the DC casting method is performed under the condition that the ingot drawing speed is 50 mm / min, and the electromagnetic stirring treatment shown in Table 2 is applied, and the thickness is 500 mm and the width is 1000 mm. An ingot was obtained.
Thereafter, a homogenization treatment at 580 ° C. × 6.0 hours was performed, followed by hot rolling, cold rolling, and final annealing to obtain an aluminum plate having a thickness of 1 mm. In addition, the cross-sectional reduction rate at the time of cold rolling, and the conditions of the final annealing performed after that were made into the conditions described in Table 2.

The structure and properties of the obtained 1 mm thick aluminum plate were evaluated. The evaluation method is as follows. The average crystal grain size and the area ratio of {110} oriented crystals were analyzed and measured by SEM-EBSD for the crystal grains in the cross section of the aluminum plate including the rolling parallel direction.
Evaluation of tensile test properties:
JIS
A JIS No. 5 test piece specified in Z 2201: 1998 was prepared, and 0.2% proof stress, tensile strength, and elongation characteristic values were measured by a tensile test at room temperature based on JIS Z 2241: 1998. These characteristics A are measured in three directions, parallel to the rolling direction (AL), perpendicular to the rolling direction (A-LT), and 45 ° (A-45) from the rolling direction. Was calculated and its value was used.
A = {(A−L) + (A−LT) + 2 × (A−45)} / 4 ・ ・ ・ ・ (1)

Evaluation of average r value:
JIS
A JIS No. 5 test piece specified in Z 2201: 1998 was prepared, and the r value was measured based on the specification of JIS G 0202: 1987 by a tensile test at room temperature. Similar to the tensile test characteristics in the previous section, measured in three directions, parallel to the rolling direction (AL), perpendicular to the rolling direction (A-LT), and 45 ° (A-45) from the rolling direction, formula (1) An average value was calculated and used.

Sphere head overhang measurement:
Extrusion molding was performed under the following conditions, and the critical height at break was measured.
Punch: 100mmφ (hemisphere), shoulder R: 50mm, die: 105mmφ, shoulder R: 4mm

Measurement of limit drawing ratio:
Under the following conditions, the maximum blank diameter that can be squeezed without breaking was obtained, and the limit squeezing ratio was calculated from the ratio to the punch diameter.
Punch: 33mmφ (cylindrical), shoulder R: 3mm, die: 35mmφ,
Wrinkle hold: 100kg Lubricant: Johnson wax # 700

The evaluation results are shown in Table 3.
Test Nos. 1 to 3 are examples in the case of an aluminum alloy not containing Mn, but the component composition and production conditions are both within the scope of the present invention, the average crystal grain size is 15 μm or less, and the {110} orientation crystal The area ratio is 27% or more, the elongation is 41% or more, the average r value is 0.87 or more, the ball head overhanging height is 34 mm or more, the limit drawing ratio is 2.17 or more, the elongation is high, the stretchability and the drawability. Is excellent.
Test Nos. 4 to 8 are examples in the case of an aluminum alloy containing Mn, but the composition and production conditions are both within the scope of the present invention, the average crystal grain size is 12 μm or less, and the {110} orientation crystal The area ratio is 27% or more, the elongation is 35% or more, the average r value is 0.95 or more, the ball head overhanging height is 33mm or more, the limit drawing ratio is 2.20 or more, the elongation is high, the overhanging property and the drawing property are Are better.

Test No. 9 is a comparative example in the case of an aluminum alloy in which Fe is low and the component composition is outside the scope of the present invention, although the manufacturing conditions are within the scope of the present invention, the average crystal grain size is 21 μm, The area ratio of {110} -oriented crystals is 21%, elongation is 44%, average r value is 0.85, ball head overhang height is 38mm, LDR is 2.07, and the elongation is high and the extensibility is excellent. Sex was not enough.
Test Nos. 10 and 11 are comparative examples in the case of an aluminum alloy having a large Ti content and a component composition outside the scope of the present invention, although the production conditions are within the scope of the present invention, Particle size is 25-28μm, area ratio of {110} orientation crystal is 23%, elongation is 37-40%, average r value is 0.82-0.84, ball head overhang height is 29-31mm, LDR (limit drawing ratio) ) Was 2.10 to 2.13, and the overhanging property and the drawing property were inferior.

Test No. 12 is a comparative example in the case of an aluminum alloy having a large amount of Mn and having a component composition outside the range of the present invention, but a coarse crystallized product was generated at the time of casting, and the plate could not be produced.
Test No. 13 is a comparative example in the case of an aluminum alloy having a large amount of Fe and a component composition outside the scope of the present invention, although the production conditions are within the scope of the present invention, the average crystal grain size is 34 μm, The area ratio of {110} -oriented crystals was 19%, elongation was 30%, average r value was 0.81, ball head overhang height was 32mm, and LDR was 2.10. .

Test No. 14 is a comparative example in which the content of Ti is an aluminum alloy having a component composition outside the scope of the present invention, and electromagnetic stirring is not performed during casting, and the production conditions are also outside the scope of the present invention. However, the average grain size is 30μm, the area ratio of {110} oriented crystals is 22%, the elongation is 40%, the average r value is 0.81, the ball overhang height is 32mm, the LDR is 2.13, and the elongation is High but poor in overhang and squeezability.
When observing the crystal grain structure of the cross section of the test sample material of test No. 4 and the comparative sample material of test No. 14, as shown in FIG. 2, the test sample material of test No. 4 is more crystalline. It can be seen that the grains are uniform and fine. It can be said that uniform refinement of the crystal grains leads to improvement of mechanical properties.

Example 2;
An example in which the component composition of the molten aluminum alloy is within the specified range and the manufacturing conditions are varied will be shown.
After melting the alloy D used in Example 1, casting, hot rolling, cold rolling, and final annealing were performed under the conditions shown in Table 2 as test Nos. 15 to 24 to obtain an aluminum plate having a thickness of 1 mm. It was. The ingot size is the same as in Example 1, with a thickness of 500 mm and a width of 1000 mm.
The structure and properties of the obtained 1 mm thick aluminum plate were evaluated. The evaluation method was the same as in Example 1, and the results are shown in Table 3.
The evaluation results are as follows.

Test No. 15 is a comparative example in which the chemical composition of the aluminum alloy is within the scope of the present invention but electromagnetic stirring is not performed during casting, and the manufacturing conditions are outside the scope of the present invention. Crystals were formed and could not be produced.
Test No. 16 is a comparative example in the case of an aluminum alloy having a large magnetomotive force of electromagnetic stirring and out of the scope of the present invention, but the average crystal grain size is 32 μm, and the area ratio of {110} oriented crystals is 21%. The elongation was 35%, the average r value was 0.80, the ball head overhanging height was 30 mm, and the LDR was 2.10. Although the elongation was high, the overhanging property and the drawability were inferior.

Test No. 17 is a comparative example in the case of an aluminum alloy that has a low frequency of electromagnetic stirring and is outside the scope of the present invention, but coarse feathery crystals were generated and could not be produced.
Test No. 18 is a comparative example in the case of an aluminum alloy having a high frequency of electromagnetic stirring and out of the scope of the present invention, but it is coarse in the center of the ingot where electromagnetic force did not move due to the skin effect. Feathery crystals were generated and could not be made.

Test No. 19 is a comparative example in the case of an aluminum alloy that has a low cross-sectional reduction rate in rolling and is outside the scope of the present invention, but the average crystal grain size is 35 μm, and the area ratio of {110} oriented crystals is 15 %, Elongation was 32%, average r value was 0.79, ball head overhang height was 29 mm, and LDR was 2.07.
Test No. 20 is a comparative example in the case of an aluminum alloy that has a high cross-sectional reduction rate in rolling and is outside the scope of the present invention.

Test No. 21 is a comparative example in the case of an aluminum alloy having a low final annealing temperature, which is outside the scope of the present invention. It was not obtained.
Test No. 22 is a comparative example in the case of an aluminum alloy that has a short final annealing time and is outside the scope of the present invention, but does not recrystallize in the final annealing, and there is a large variation in any of the characteristics, and a significant value is obtained. It was not obtained.

Test No. 23 is a comparative example in the case of an aluminum alloy having a high final annealing temperature and out of the scope of the present invention, but the average grain size is 82 μm, the area ratio of {110} oriented crystals is 12%, and the elongation is Was 30%, the average r value was 0.72, the ball head overhanging height was 25 mm, and the LDR was 1.98.
Test No. 24 is a comparative example in the case of an aluminum alloy that has a long final annealing time and is outside the scope of the present invention, but the average crystal grain size is 101 μm, the area ratio of {110} oriented crystals is 9%, and the elongation is Was 28%, the average r value was 0.68, the ball head overhang height was 23 mm, and the LDR was 1.95, and the elongation, overhang property and drawability were inferior.

The figure explaining the crystal grain evaluation section of an aluminum alloy plate Observation of crystal grain structure of cross section of aluminum alloy sheet after annealing

Claims (5)

  Fe is contained in an amount of 1.0 to 2.0% by mass, the balance is made of aluminum and inevitable impurities, and Ti as the inevitable impurities has a component composition limited to 0.01% by mass or less, and the average crystal grain size is 20 μm or less, {110 } An aluminum alloy plate excellent in formability, characterized by having a structure in which the area ratio of orientation crystals is adjusted to 25% or more.   Furthermore, the aluminum alloy plate excellent in formability of Claim 1 which has a component composition which contains 2.0 mass% or less of Mn.   The aluminum alloy melt having the component composition according to claim 1 or 2 is DC cast while electromagnetically stirring, and the obtained ingot is subjected to homogenization heat treatment, rolling, and final annealing, and has excellent formability A method for producing an aluminum alloy plate.   The method for producing an aluminum alloy plate excellent in formability according to claim 3, wherein the electromagnetic stirring is performed with a magnetomotive force of 15000 to 25000 At and a frequency of 10 to 30 Hz.   The aluminum alloy excellent in formability according to claim 3 or 4, wherein the final annealing is a batch annealing treatment at 350 to 500 ° C for 1 to 10 hours or a continuous annealing treatment at 400 to 550 ° C for 1 second to 10 minutes. A manufacturing method of a board.