JP2005139495A - Aluminum alloy sheet for forming, and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an Al-Mg-Si based Al alloy sheet for forming which has excellent strength and deep drawability, and is used for an automobile body sheet or the like. <P>SOLUTION: The aluminum alloy sheet has a composition comprising 0.3 to 2.0% Mg and 0.3 to 2.5% Si, and, if required, comprising one or more kinds of metals selected from 0.05 to 1.5% Cu, 0.01 to 0.8% Mn, 0.01 to 0.3% Cr and 0.01 to 0.2% Zr, and the balance substantially Al, and in which, over the whole region of the sheet thickness, the orientation density in the ä100} face is <1, the orientation density in the ä111} face is >1, and the average r value is ≥0.9. In its production method, after hot rolling accompanied by recrystallization, different peripheral speed rolling is performed at a draft of ≥30% in the nonrecrystallization temperature region of 170 to 350°C, and thereafter, solution treatment accompanied by recrystallization is performed. Further, different peripheral speed rolling is performed at a peripheral speed ratio of 1:1.2 or higher in particular. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an aluminum alloy plate for forming used for body parts of automobiles, other various vehicle parts, and various electronic / electric equipment parts such as chassis and panels of electronic / electric equipment, and a manufacturing method thereof, In particular, the present invention relates to an aluminum alloy plate for forming made of an Al-Mg alloy having excellent strength and formability after baking and a method for producing the same.

  Conventionally, cold rolled steel sheets were often used for automobile body sheets, but recently there has been a growing demand for lighter automobiles to improve fuel economy in order to reduce global warming and reduce energy costs. Therefore, instead of the conventional cold-rolled steel plate, there is an increasing tendency to use an aluminum alloy plate having substantially the same strength as the cold-rolled steel plate and a specific gravity of about 1/3 for the body sheet of an automobile. Recently, aluminum alloy plates are often used for molded parts such as panels and chassis of electronic and electric devices other than automobiles.

  By the way, as an aluminum alloy plate as such a forming material, conventionally, an Al—Mg—Si-based AA 6016 alloy, AA 6022 alloy, AA 6111 alloy T4 treatment material and the like are most widely used. As a method for producing a forming material made of such an Al—Mg-based aluminum alloy, conventionally, casting is generally performed by a DC casting method and subjected to a homogenization treatment, followed by hot rolling and further cold rolling. A method of applying a solution treatment to the product sheet thickness is further applied. However, the Al-Mg-based aluminum alloy sheet for forming work manufactured by such a conventional general method has the same workability as that of cold-rolled steel sheet, but its formability, especially deep drawability, is cold-rolled. The reality is that it is inferior to steel plates.

Here, in cold-rolled steel sheets, the Rankford value (r value) has been widely used as an index of formability, particularly deep drawability. The higher the rankford value, especially the average rankford value, the better the deep drawability. Here, the average rankford value is an average value of rankford values (r ₀ , r ₄₅ , r ₉₀ ) measured in directions of 0 °, 45 °, and 90 ° with respect to the rolling direction. Value = (r ₀ + 2 × r ₄₅ + r ₉₀ ) / 4. On the other hand, in general, it is well known that deep drawability is greatly influenced by the texture in a forming material. In cold-rolled steel sheets, it is known that increasing the orientation density of the {111} plane, which is the main orientation of the rolling texture, increases the average rankford value and improves deep drawability. And in the cold-rolled steel sheet, since the main orientation is the {111} plane as described above, it is easy to increase the orientation density of the {111} plane and improve the deep drawability, and the method for that is already sufficient. Established.

  On the other hand, in the case of an aluminum alloy which is a face-centered cubic metal, if the heat treatment is performed by a conventional general method, not only the {111} plane effective for improving the formability is formed, but rather the formability is improved. The azimuthal density of the {100} plane to be obstructed becomes the main azimuth, and the average Rankford value cannot be sufficiently increased, and it is difficult to improve the moldability, particularly the deep drawability.

  Incidentally, the applicant of the present application has already disclosed a special rolling method in Patent Document 1 as a method for producing an Al—Mg-based aluminum alloy plate that is an alloy system different from the Al—Mg—Si system targeted by the present invention. Although a method of applying the warm rolling method is disclosed, the method of Patent Document 1 is still insufficient for improving the deep drawability, and it is not suitable for Al—Mg—Si based alloys which are different alloy systems. When applied, it is not immediately considered effective to improve deep drawability. Further, the applicant of the present application, as shown in Patent Document 2, as a method for producing an aluminum alloy plate for the purpose of refining crystal grains of an Al—Mg—Si based aluminum alloy plate, Although the method of applying the warm different peripheral speed rolling which makes the rotational peripheral speed of a rolling roll different is disclosed, the method of this patent document 2 is not originally intended to improve formability, particularly deep drawability. In addition, there is a severe restriction on the control of the structure before performing the warm different speed rolling, and there is a problem that the restriction is too large to apply to the production on a mass production scale industrially.

  Further, Patent Document 3 discloses that <111> // ND-oriented grains having an angle difference of 15 ° or less are heated in an area ratio after being subjected to hot or warm or cold different peripheral speed rolling and then heated to a recovery temperature or higher. Although it is disclosed that if it is 10% or more, the moldability is excellent, in order to further improve the moldability, it is necessary to reduce the orientation density of {100} planes that inhibit the moldability as described above. The point is not considered in the invention of Patent Document 3, and therefore, it is still insufficient to improve the moldability reliably and stably.

JP 7-41896 A JP 2001-279405 A JP 2003-305503 A

  As described above, as a raw material for forming such as an automobile body sheet, an Al—Mg—Si based alloy plate obtained by a conventional ordinary manufacturing method has a formability, in particular, a deep drawability as a cold-rolled steel plate. It was not enough compared. In addition, as a molding material for applications such as body sheets for automobiles, it is of course required to have high strength mainly due to demands for thinning and weight reduction, and particularly high strength after paint baking. Desired.

  The present invention has been made against the background of the above circumstances, and has been widely used as a molding process for various vehicle parts such as automobile body sheets or various electronic / electric equipment parts such as panels of electronic / electric equipment. As an aluminum alloy plate for forming processing of Al-Mg-Si type used by drawing, to provide an aluminum alloy plate having high strength after baking and at the same time excellent in forming workability, particularly deep drawability. It is the purpose.

  In order to improve the deep drawability of the forming material, it is necessary to appropriately control the texture as described above to increase the orientation density of the {111} plane. As a means for increasing the {111} plane orientation density in the face-centered cubic metal, there is a method of imparting shear deformation to the material. Whether the metal to be processed is face-centered cubic or body-centered cubic and whether the processing is rolling or shearing are closely related to each other. It is known that the texture almost coincides with the shear texture of the face-centered cubic metal. Therefore, in the present invention as well, the Al-Mg-Si aluminum alloy, which is a face-centered cubic metal, is given shear deformation to increase the orientation density of the {111} plane and improve the deep drawability.

  Here, also in normal hot rolling and cold rolling, shear deformation occurs in the extreme surface layer of the material in contact with the rolling roll due to friction at the interface between the material and the rolling roll surface. Therefore, as one of the techniques for increasing the orientation density of the {111} plane and improving the deep drawability by utilizing the friction at the interface more effectively, in the invention of Patent Document 1 already described, warm rolling is performed. However, by simply applying warm rolling, the shear deformation region due to friction at the interface between the rolling roll surface and the material as described above is sufficiently expanded to the inside of the thickness direction of the material. It is difficult. That is, warm rolling is one of the rolling methods using a conventional ordinary rolling mill, but the idea on the extension line of the method using such a conventional ordinary rolling mill is that the shear deformation region of the material is determined. It was difficult to obtain an aluminum alloy plate having a sufficiently high {111} plane orientation density as a whole by sufficiently expanding the inside of the plate. Therefore, as a result of further experiments and examinations by the present inventors, a different peripheral speed from the conventional general rolling method is combined with a method of reducing the deformation resistance of the material by setting the rolling temperature region as a warm rolling temperature region. Rolling, that is, by changing the relative speed of the upper roll and the lower roll relative to the material and applying a technique for forcibly applying shear deformation, the orientation density of the {111} plane is sufficiently increased to the inside of the plate during rolling, As a result, it has been found that the deep drawability can be drastically improved as compared with the Al—Mg—Si based aluminum alloy sheet obtained by the conventional method, and the present invention has been made.

  That is, the present invention not only appropriately adjusts the component composition of the alloy, but also provides a forming aluminum alloy sheet having an appropriately controlled texture and a method for obtaining the appropriate texture. Yes.

  Specifically, the aluminum alloy for forming according to the invention of claim 1 contains Mg 0.3 to 2.0%, Si 0.3 to 2.5%, the balance being Al and inevitable impurities The average rankford value is 0.9 or more, and the orientation density of the {100} plane by X-ray diffraction is less than 1 and the orientation density of the {111} plane exceeds 1 over the entire thickness. It is characterized by.

  The invention of claim 2 is the aluminum alloy sheet for forming according to claim 1, wherein the material aluminum alloy is further Cu 0.05 to 1.5%, Mn 0.01 to 0.8%, Cr 0.01 to It is characterized by containing one or more of 0.3% and Zr 0.01-0.2%.

  Furthermore, the invention of claim 3 is a method for producing an aluminum alloy sheet for forming according to claim 1 or claim 2, wherein the ingot of the aluminum alloy having the above composition is hot-rolled with recrystallization. To a plate thickness of 2 to 10 mm, and then rolling at a different peripheral speed at a reduction rate of 30% or more in a non-recrystallization temperature range within a range of 170 to 350 ° C., and further solution treatment with recrystallization. As a result, the average rankford value is 0.9 or more, and the orientation density of {100} plane by X-ray diffraction is less than 1 and the orientation density of {111} plane exceeds 1 by X-ray diffraction over the entire plate thickness. An aluminum alloy plate for use is obtained.

  According to a fourth aspect of the present invention, in the method for producing an aluminum alloy sheet for forming according to the third aspect, the different peripheral speed rolling is performed under a condition that a roll peripheral speed is 1: 1.2 or more. It is what.

  The aluminum alloy plate for forming according to the inventions of claims 1 and 2 has high strength required for an automobile body or the like as an Al-Mg-Si aluminum alloy plate, particularly high strength after paint baking, Formability, especially deep drawability and bendability are significantly better than before. In addition, according to the method for producing an aluminum alloy sheet for forming according to the third and fourth aspects of the present invention, as described above, it has high strength after baking and, at the same time, has formability, particularly deep drawability and bendability. An aluminum alloy plate significantly better than that can be obtained practically and easily by means of a mass-scale apparatus.

  The aluminum alloy plate according to the present invention is most suitable for various vehicle parts such as automobile bodies, but is not limited to this, and can be used for various electrical equipment chassis and panels and other various parts for molding. is there.

  First, the reasons for limiting the component composition of the aluminum alloy used as the material of the aluminum alloy plate for forming according to the present invention will be described.

Mg:
Mg is a basic component element together with Si, which will be described later, in the aluminum alloy that is the subject of the present invention, strength (material strength before paint baking treatment), strength after paint baking treatment (so-called bake hard property), In addition, it contributes to improvement of moldability, particularly elongation, deep drawability, and stretchability. If the amount of Mg is less than 0.3%, not only sufficient strength and bake hardness can be obtained, but also the elongation, deep drawability and stretchability are inferior. On the other hand, if it exceeds 2.0%, the strength becomes too high. Elongate and formability decreases. Therefore, Mg was made into the range of 0.3-2.0%.

Si:
Si is a basic component element together with the aforementioned Mg in the aluminum alloy targeted by the present invention, and contributes to improvement in strength, bake hardness, and formability, particularly elongation, deep drawability, and stretchability. . If the Si content is less than 0.3%, not only sufficient strength and bake hardness can be obtained, but also elongation, deep drawability, and extrudability are inferior. On the other hand, if it exceeds 2.5%, coarse metallic Si is precipitated. However, deep drawability is reduced. Therefore, Si is set within a range of 0.3 to 2.5%.

  Furthermore, in the aluminum alloy plate for forming according to the invention of claim 2, in addition to the above Mg, an alloy added with one or more of Cu, Mn, Cr, and Zr as a positive additive element is used. The reason for these additions is as follows.

Cu:
Cu contributes to strength improvement, particularly strength after baking by painting. If the amount of Cu is less than 0.05%, the effect of improving the strength cannot be obtained. On the other hand, if it exceeds 1.5%, the elongation, formability, and corrosion resistance are lowered. Within the range of 1.5%.

Mn:
Mn is effective in improving the strength and refining crystal grains after heat treatment. If the amount of Mn is less than 0.01%, strength and grain refining effects cannot be obtained. On the other hand, if it exceeds 0.8%, coarse Al-Mn and Al-Mn-Si intermetallic compounds are formed. Degradation of moldability, especially hole expansibility, bulgeability and bendability. Therefore, the amount of Mn in the case of adding Mn is set within a range of 0.01 to 0.8%.

Cr:
Cr is effective in improving the strength and refining crystal grains after heat treatment. If the Cr content is less than 0.01%, the strength and grain refining effect cannot be obtained. On the other hand, if it exceeds 0.3%, a giant intermetallic compound of Al-Cr is formed, and the formability, particularly the hole expandability. , Deteriorates overhang and bendability. Therefore, the amount of Cr in the case of adding Cr is set within a range of 0.01 to 0.3%.

Zr:
Zr is effective in refining crystal grains after heat treatment. If the amount of Zr is less than 0.01%, the effect of refining crystal grains cannot be obtained. On the other hand, if it exceeds 0.2%, a giant intermetallic compound is formed. Deteriorate. Therefore, the amount of Zr in the case where Zr is added is set in the range of 0.01 to 0.2%.

  Other than the above alloy elements, basically, Al and inevitable impurities may be used.

  In general aluminum alloys, Fe is usually contained as an inevitable impurity. However, Fe forms an Al—Fe-based intermetallic compound, and formability, in particular, elongation, bendability, and hole expandability. Since it becomes a factor of deterioration, it is desirable to regulate the amount of Fe to less than 0.25%.

In general aluminum alloys, a small amount of Ti is often added alone or in combination with a small amount of B or C in order to refine the ingot crystal grains. It is permissible to add. However, if the Ti content exceeds 0.15%, coarse particles of primary crystal TiAl ₃ may be generated. Therefore, the Ti content is preferably 0.15% or less, and if the B content exceeds 500 ppm, the coarse TiB _{Since a} linear defect due to _two particles may occur, the B content is preferably 500 ppm or less, and if the C content exceeds 500 ppm, coarse graphite may be generated. Therefore, the C content is 500 ppm or less. It is desirable.

  In addition, when casting an aluminum alloy containing Mg, a small amount of Be is often added to prevent the oxidation of the molten metal, but in the case of this invention as well, the addition of 500 ppm or less of Be deteriorates the other performance. I will not let you.

  In addition, the content range of Cu, Mn, Cr, and Zr specified in claim 2 is shown as a range in the case where each is positively added, and each contains an amount smaller than the lower limit as an impurity. If you do not exclude.

  Furthermore, in the aluminum alloy sheet for forming according to the present invention, as a condition regarding the recrystallization texture, the orientation density of the {100} plane by X-ray diffraction is less than 1 and the orientation density of the {111} plane is 1 over the entire thickness. And the average rankford value is 0.9 or more as an index of deep drawability. Here, the {111} plane is an advantageous surface for deep drawability as described above, and if the orientation density of the {111} plane is 1 or less, good deep drawability cannot be obtained. On the other hand, the {100} plane is disadvantageous for moldability, particularly deep drawability. When the orientation density of the {100} plane is 1 or more, good deep drawability cannot be obtained. The Rankford value is also used as an index of moldability, particularly deep drawability. When the average Rankford value shown by the above-described formula is less than 0.9, good deep drawability cannot be obtained. Therefore, in the present invention, these conditions are defined as texture conditions and characteristic conditions of the aluminum alloy sheet for forming. Even within these ranges, it is more preferable that the {111} plane orientation density is 1.3 or more, the {100} plane orientation density is 0.5 or less, and the average rankford value is 1.0 or more. In general, the rolled plate generally has its texture changed from the plate surface to the inside of the plate thickness as described above. However, in order to improve formability, the above { 111} plane and {100} plane orientation density needs to be obtained. Therefore, in the present invention, it is defined that the above-mentioned orientation density conditions of {100} plane and {111} plane are satisfied over the entire plate thickness. In addition, in an actual aluminum alloy plate, it is impossible to measure the orientation density strictly at all positions in the entire thickness of the plate. Therefore, in actual measurement, the position of the plate surface and the thickness direction from the plate surface. Measure the azimuth density at each of the above positions, and measure the azimuth density at each of the above positions. It is sufficient if the above conditions are satisfied.

  Next, a method for producing the aluminum alloy plate for forming as described above will be described.

  First, a molten alloy having the above-described composition is melted in accordance with a conventional method, and cast by a normal casting method such as a DC casting method (semi-continuous casting method). The resulting ingot is usually subjected to a homogenization treatment. This homogenization process is a process for homogenizing the ingot structure, improving the formability of the final plate, and stabilizing the recrystallized grains during the final annealing. The conditions for the homogenization treatment are not particularly limited. However, if the treatment temperature is less than 450 ° C., a sufficient effect cannot be obtained. On the other hand, if the treatment temperature exceeds 570 ° C., eutectic melting may occur, and if the treatment time is less than 0.5 hours. A sufficient effect cannot be obtained, and if it exceeds 24 hours, the effect is saturated and the economic efficiency is impaired. Therefore, it is desirable that the homogenization treatment is performed at 450 to 570 ° C. for 0.5 to 24 hours.

  After the homogenization treatment, hot rolling with recrystallization is performed. This hot rolling may be performed according to a conventional general method, and may be performed immediately after the homogenization treatment, or may be performed by cooling once after the homogenization treatment and then reheating. Here, hot rolling accompanied by recrystallization means hot rolling in which recrystallization occurs until hot rolling is completed, and in many cases of conventional general hot rolling, too. It is usually accompanied by recrystallization. In order to cause recrystallization until the hot rolling is completed in this way, rolling may be started in a temperature range higher than the recrystallization temperature (preferably a temperature sufficiently higher than the recrystallization temperature). In general, rolling may be started in a high temperature range that normally exceeds 350 ° C. If the end thickness (upward thickness) of such hot rolling is less than 2 mm, the rolling rate up to the subsequent product thickness will be small, and the reduction rate in warm different peripheral rolling described later will be insufficient. At the same time, cracks at the ends are likely to occur during hot rolling. On the other hand, if the finished thickness of the hot rolling exceeds 10 mm, the rolling rate up to the product thickness after that increases, and a large number of times are required for rolling, thereby hindering productivity. Therefore, the finished plate thickness of the hot rolling is set in the range of 2 to 10 mm.

  After the hot rolling, further rolling is performed in order to obtain a predetermined product sheet thickness. In the method of the present invention, particularly from 170 to 350 ° C. between the sheet thickness after hot rolling and the final product sheet thickness. In order to obtain the recrystallized texture as described above, it is important to perform the different peripheral speed rolling at a reduction rate of 30% or more in the non-recrystallization temperature range (warm rolling temperature range) within the range.

  Here, the different circumferential speed rolling is a method of rolling the aluminum alloy sheet to be rolled with the circumferential speed of the upper rolling roll different from the circumferential speed of the lower rolling roll. As a specific rolling mechanism, For example, the upper and lower rolls are controlled by separate motors to make the upper and lower roll rotation speeds different, or the driving force of one motor is transmitted to the upper and lower rolls via gears with different ratios to There are various methods, such as a method for differentiating the number of rotations and a method for differentiating the roll peripheral speed by making the diameters of the upper and lower rolls different, but in this invention the mechanism of the rolling mill is particularly restricted is not.

  In the method of the present invention, by applying different peripheral speed rolling in a temperature range of 170 to 350 ° C. (non-recrystallization temperature range), a large shear deformation can be given to the aluminum alloy sheet during rolling, The shear deformation reaches the inside of the thickness direction of the aluminum alloy plate, and as a product plate after solution treatment accompanied by subsequent recrystallization, the orientation density of {111} plane is sufficiently high and deep drawability. An excellent product can be obtained with certainty. Here, if the rolling temperature in different peripheral speed rolling is less than 170 ° C., the material has a large deformation resistance, and the shear deformation does not reach the inside of the plate thickness. On the other hand, if the rolling temperature exceeds 350 ° C., recrystallization occurs during rolling, and preferable shear deformation cannot be obtained. Further, when the rolling reduction of different peripheral speed rolling is less than 30%, the amount of shear deformation is small, and a preferable texture cannot be obtained by solution treatment with subsequent recrystallization. Further, in different circumferential speed rolling, if the circumferential speed ratio of the upper and lower rolls is less than 1: 1.2, it is difficult to impart sufficient shear deformation, so the ratio of the circumferential speeds of the upper and lower rolls (different circumferential speed ratio). ) Is preferably 1: 1.2 or more, and more preferably 1: 1.5 or more. If solution treatment is performed without imparting sufficient shear deformation in such different peripheral speed rolling, the {100} plane orientation density is increased, and the {111} plane orientation density is not sufficiently increased. The deep drawability of the product plate is not sufficiently improved. Therefore, in the present invention, the rolling temperature is defined as a temperature range of 170 to 350 ° C. (non-recrystallization temperature range), the rolling reduction is defined as 30% or more, and the different circumferential speed ratio of the upper and lower rolls. Is preferably 1: 1.2 or more, more preferably 1: 1.5 or more.

  It should be noted that the different peripheral speed rolling in the non-recrystallization temperature range of 170 to 350 ° C. as described above (hereinafter, such different peripheral speed rolling in the non-recrystallization temperature range of 170 to 350 ° C. is referred to as “warm different peripheral speed”. As described above, “rolling” is equivalent to warm rolling without recrystallization. However, such warm non-recrystallization rolling in the non-recrystallization temperature range is heat with recrystallization. After the end of hot rolling (in some cases, after further cold rolling as will be described later), it may be reheated again, or in the same hot rolling mill, After the last recrystallization in the rolling process, controlled cooling may be performed so that the temperature is within the range of 170 to 350 ° C., and the process may subsequently be performed as warm different peripheral speed rolling.

  Furthermore, 30% or more warm different peripheral speed rolling in the temperature range of 170 to 350 ° C. without recrystallization as described above is basically hot rolling with recrystallization and final sheet thickness. What is necessary is just to perform between the solution treatment accompanying recrystallization with respect to the rolled sheet which became, and depending on the desired final plate | board thickness, you may perform cold rolling in combination with warm different peripheral speed rolling. In other words, even if only the hot differential rolling is performed between the hot rolling and the solution treatment, or the hot differential rolling is performed after the hot rolling and then the cold rolling is performed and then the solution treatment is performed. In addition, after the hot rolling, cold rolling may be performed once, followed by warm different peripheral speed rolling and then solution treatment. However, when cold rolling is performed, the orientation density of {100} planes may increase in the solution treatment, and deep drawability may be impaired. Therefore, even when cold rolling is performed, the total rolling ratio is acceptable. It is desirable to make it as small as possible, and it is usually desirable to have a cold rolling rate of 70% or less.

  In addition, in each rolling process after hot rolling with recrystallization as described above and before solution treatment, in general, intermediate annealing is often performed to improve rollability. In the case of this method, since warm different peripheral speed rolling is performed during that time, there is little need to perform intermediate annealing for improving the rolling property. However, depending on the case, intermediate annealing may be performed, and this intermediate annealing may be performed before, after (before cold rolling) or in the middle of warm different peripheral speed rolling, and further in the middle of cold rolling. . The conditions for the intermediate annealing performed as necessary are not particularly limited. In the case of batch-type intermediate annealing, heating is maintained at 250 to 450 ° C. for 0.5 to 24 hours, and in the case of the continuous annealing method, 350 to It is preferable that the temperature is not maintained at 580 ° C. or maintained within 5 minutes. In the case of batch-type intermediate annealing, if the annealing temperature is less than 250 ° C., sufficient intermediate annealing effect cannot be obtained, and if it exceeds 450 ° C., the recrystallized grains become coarse and formability decreases, and the annealing time is reduced to 0. If it is less than 5 hours, a sufficient effect cannot be obtained. On the other hand, if it exceeds 24 hours, the effect is saturated and the economical efficiency is impaired. On the other hand, in the case of the intermediate annealing of the continuous annealing method, a sufficient effect cannot be obtained if the temperature is less than 350 ° C., and if it exceeds 580 ° C., the recrystallized grains may be coarsened and formability may be deteriorated. If it exceeds 5 minutes, the recrystallized grains may be coarsened to deteriorate the moldability.

  As described above, a rolled sheet having a final product thickness obtained by performing hot differential rolling after hot rolling, or a rolled product having a final product thickness obtained by combining warm differential rolling and cold rolling ( In any case, including the case where intermediate annealing is performed), in order to improve the formability by finally recrystallizing, at the same time, solute elements such as Mg, Si, and Cu are solid-dissolved to impart bake hardness. Then, a solution treatment is performed. This solution treatment involves recrystallization, and as described above, recrystallization reduces the orientation density of the {100} plane that impairs the formability and improves the deep drawability of the {111} plane. By increasing the azimuthal density, the average Rankford value can be increased to 0.9 or more.

  The solution treatment is desirably performed by a continuous annealing method using a continuous annealing furnace, and the condition in that case is preferably 450 to 580 ° C. with no holding time or holding within 5 minutes. Moreover, a batch type solution treatment can also be performed, and in that case, it is preferable to perform the conditions according to JIS W1103 (1985) (516 to 579 ° C. × 0.5 hours or more). In the case of the continuous annealing method, if the annealing temperature is less than 450 ° C., it will not be completely recrystallized, so good moldability will not be obtained, and the solid solution of solute elements such as Mg, Si, Cu will be insufficient and good baking will be achieved. If the hardness is not obtained, on the other hand, if the annealing temperature exceeds 580 ° C., not only does the moldability decrease due to eutectic melting, but the recrystallized grains become coarse, causing rough skin after molding, resulting in poor appearance, There is a possibility that the thickness of the oxide layer on the surface increases and the chemical conversion treatment performance is lowered. Further, if the heat treatment for more than 5 minutes is performed by the continuous annealing method, the effect of solution treatment is saturated, not only the economic efficiency is impaired, but also the thickness of the oxide layer on the surface is increased, and the chemical conversion treatment performance is lowered.

  In addition, since the Al-Mg-Si-based alloy has high room temperature aging after solution treatment, if the period until processing after solution treatment is long, the strength increases and the formability decreases. Therefore, in order to alleviate such room temperature aging, after the solution treatment, continuous annealing at 150 to 300 ° C. within 5 minutes or batch annealing at 60 to 150 ° C. for 30 minutes to 24 hours may be performed. In the case of continuous annealing, the main purpose is to reduce the vacancy concentration, which causes room temperature aging. If the temperature of continuous annealing is less than 150 ° C, the vacancy concentration is insufficiently reduced. Since a stable phase that does not contribute is formed, the strength after baking is reduced. Moreover, in holding | maintenance for 5 minutes or more in continuous annealing, a stable phase is formed and the intensity | strength after baking coating is reduced. In the case of batch annealing, the main purpose is to age-harden in advance, but there is no effect when the temperature of batch annealing is less than 60 ° C, while when it exceeds 150 ° C, the aging is too advanced and the strength becomes high, and the formability is high. descend. Further, if the heating and holding time in the case of batch annealing is less than 30 minutes, curing is insufficient, while if it exceeds 24 hours, it becomes uneconomical.

  Each alloy having the component composition shown in alloy codes A, B, C, and D of Table 1 was melted in accordance with a conventional method, and cast into an ingot having a thickness of 80 mm, a width of 200 mm, and a length of 1500 mm by laboratory-scale DC casting. . The obtained ingot was homogenized at 510 ° C. for 4 hours, and then hot rolled to a thickness of 2 mm or 6 mm according to a conventional method. The hot rolling finish temperature is about 250 ° C. when the temperature rises by 6 mm, and about 200 ° C. when the temperature rises by 2 mm. In each case, the flatness of the grain structure of the cross section in the rolling direction (L cross section) of the hot rolled sheet is observed. As a result, it was confirmed that recrystallization occurred during hot rolling. These hot-rolled sheets were subjected to thermomechanical treatment under various conditions as shown in production process numbers 1 to 11 shown in Table 2. In other words, it is subjected to warm differential rolling or cold rolling, or a combination of warm differential rolling and cold rolling, or partly subjected to intermediate annealing during the rolling process, and the final obtained A solution heat treatment was performed on a rolled plate having a thickness. Here, the warm different peripheral speed rolling uses a warm different peripheral speed rolling machine in which the upper and lower rolls are driven by independent motors, the rotation speed of the low speed roll is constant at 20 m / min, and the high speed roll The rotational speed of was changed according to the set different peripheral speed ratio.

  Here, in Table 2, production process numbers 1 and 2 are examples of the present invention in which warm different peripheral speed rolling within the condition range defined in the present invention was performed between hot rolling and solution treatment ( However, production process number 2 is further subjected to intermediate annealing after different speed rolling), and production process numbers 3 and 4 are both warm different circumferences defined in the present invention between hot rolling and solution treatment. A comparative example in which only the warm different peripheral speed rolling out of the rapid rolling temperature range was performed, and production process number 5 is the warm different peripheral speed different peripheral speed defined in the present invention between the hot rolling and the solution treatment. Comparative examples in which only warm differential rolling out of the specific range was performed, and production process numbers 6 and 9 are inventions in which cold rolling and warm differential circumferential rolling were combined within the range specified in the present invention. Example (however, manufacturing process number 6 is further subjected to intermediate annealing after different peripheral speed rolling) ), Production Process Nos. 7 and 8 are comparative examples in which the warm different circumferential rolling and the cold rolling are combined with each other, and the production process No. 10 is different from the range specified in the present invention. Invention example No. 11 produced by combining cold rolling, warm different peripheral speed rolling, and cold rolling within the condition range defined by the present invention between hot rolling and solution treatment, manufacturing process number 11 is hot rolling This is a conventional example in which cold rolling and intermediate annealing are performed without performing warm different peripheral speed rolling between the steel and the solution treatment. In addition, intermediate annealing was performed by manufacturing process numbers 2, 6, and 11 using a salt bath corresponding to the continuous annealing method and holding at 500 ° C. for 30 seconds. In addition, the solution treatment was performed by forced air cooling after holding at 530 ° C. for 30 seconds using a salt bath corresponding to the continuous annealing method.

  Each plate after solution treatment obtained as described above is subjected to a tensile test in the rolling direction to examine the mechanical properties (TS, YS, EL) in the rolling direction, and 185 ° C. assuming a coating baking process. The proof stress (ABYS; bake hard property) after heating for 20 minutes was examined. Further, as a formability evaluation, tensile test specimens were taken in the 0 °, 45 °, and 90 ° directions with respect to the rolling direction, and the Rankford value in each direction was measured to obtain the average Rankford value calculated from the above formula. In addition, the Erichsen value, LDR (limit drawing ratio), and 180 ° limit bendability were examined. The 180 ° limit bendability is determined by visually observing the appearance of the test specimen after bending, rank 1: cracking, rank 2: significant necking, rank 3: slightly necking, rank 4: minor necking, rank 5: No constriction was generated, and the evaluation was made according to the above five steps. Further, rolling on pure aluminum powder (random orientation sample) by X-ray diffraction at the plate surface position, the plate thickness direction 1/4 thickness position, the plate surface direction 1/2 thickness position, and the above positions. The pole figure of the plate was measured, and three-dimensional orientation distribution density (ODF) analysis was performed to examine {100} plane orientation density and {111} plane orientation density at each position. Here, the orientation density of {100} plane means the cube orientation, that is, {100} <001> orientation: density of ψ2 = 0 °, φ = 0 °, ψ1 = 0 ° in the ODF diagram, and {111 } The orientation density of the plane is {111} <110> orientation or {111} <112> orientation having a large contribution to formability: ψ2 = 45 ° in the ODF diagram, ψ1 = 30 ° in φ = 55 °, 60 ° It means the maximum value. These measurement results are shown in Tables 3 to 6.

  As is apparent from Tables 3 to 6, in the present invention example in which the warm different peripheral speed rolling was performed under conditions satisfying the temperature range, rolling rate, and different peripheral speed ratio specified in the present invention, The {100} plane orientation density is less than 1 at each position, and the {100} plane orientation density can be regarded as less than 1 over the entire plate thickness. Similarly, the {111} plane orientation at each position in the plate thickness direction The density exceeds 1, and the {111} plane orientation density can be considered to exceed 1 over the entire plate thickness, and thus has a recrystallized texture that is advantageous for formability, particularly deep drawability. In addition, the average Rankford value is 0.9 or more, the Erichsen value, the formability and bendability evaluated by LDR are excellent, and the strength after baking is clear. It is. On the other hand, in the case of each comparative example in which the warm different peripheral speed rolling was not performed under the conditions satisfying the temperature range, rolling rate, and different peripheral speed ratio specified in the present invention, the orientation of the {100} plane is all The density is much higher than 1, the orientation density of {111} plane is less than 1, a recrystallized texture that is disadvantageous to deep drawability is formed, and the average Rankford value is also less than 0.9. It has been found that improvement in formability and bendability evaluated by Erichsen value and LDR is not observed.

Claims (4)

  Mg 0.3-2.0% (mass%, the same shall apply hereinafter), Si 0.3-2.5%, the balance being aluminum alloy consisting of Al and inevitable impurities, and the average Rankford value of 0 .9 or more, and the orientation density of the {100} plane by X-ray diffraction is less than 1 and the orientation density of the {111} plane exceeds 1 over the entire plate thickness, and the aluminum alloy plate for forming processing .   The aluminum alloy sheet for forming according to claim 1, wherein the material aluminum alloy further comprises Cu 0.05 to 1.5%, Mn 0.01 to 0.8%, Cr 0.01 to 0.3%, Zr 0.01. An aluminum alloy plate for forming, characterized by containing one or more of ˜0.2%. In the method for manufacturing the aluminum alloy sheet for forming according to claim 1 or 2,
The aluminum alloy ingot having the above component composition is subjected to hot rolling accompanied by recrystallization to a thickness of 2 to 10 mm, and then reduced by 30% or more in a non-recrystallization temperature range within a range of 170 to 350 ° C. Is subjected to a solution treatment accompanied by recrystallization, whereby the average rankford value is 0.9 or more, and the orientation of the {100} plane by X-ray diffraction over the entire plate thickness A method for producing an aluminum alloy plate for forming, wherein the aluminum alloy plate for forming has a density of less than 1 and the orientation density of {111} planes exceeds 1. In the manufacturing method of the aluminum alloy plate for shaping | molding of Claim 3,
The method for producing an aluminum alloy sheet for forming, characterized in that the different peripheral speed rolling is performed under a condition that a roll peripheral speed is 1: 1.2 or more.