JP2007039773A - Aluminum alloy plate to be formed and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an Al alloy plate which has superior hem formability, has little bending anisotropy, can adequately adjust the strength after having been painted and baked, causes little aging at room temperature, and is suitable for an automotive body sheet. <P>SOLUTION: The aluminum alloy plate to be formed employs an Al-Mg-Si-based Al alloy or an Al-Mg-Si-Cu-based Al alloy as a base material; contains a cubic crystal of which the orientation density is 10 times of or more than that in a random crystal orientation sample; contains crystals having orientations of ä011}<211>, ä123}<634> and ä112}<111>, of which the total orientation density is four times or more than that in the random crystal orientation sample; has earing rates of 5% or more each in 0 degree and 90 degrees; and a grain size number of No. 4 or more specified in ASTM. The manufacturing method comprises the steps of: homogenizing the ingot at 480°C or higher; cooling it; starting hot rolling at 300°C or higher; finishing the hot rolling at 100 to 350°C; skipping cold rolling; solution-treating it at 480°C or higher; and cooling it at 100°C/min or higher. The method may further include the step of stabilization-treating the plate which has been solution-treated, or solution-treated and left at room temperature, at a temperature between 50 and less than 150°C for one hour or longer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to automobile parts and parts such as body sheets and body panels of automobiles, other parts and parts of ships, aircrafts, etc., as well as various building materials, structural materials, other various machinery and equipment, home appliances and parts thereof, etc. The present invention relates to Al-Mg-Si-based or Al-Mg-Si-Cu-based aluminum alloy sheets used for forming and painting and baking, and a method for producing the same. The present invention relates to an aluminum alloy sheet for forming and having a good (hem bendability), suitable strength after baking, and little change with time at room temperature (room temperature), and a method for producing the same.

  Conventionally, as a body sheet of an automobile, a cold-rolled steel sheet has been mainly used, but recently, an aluminum alloy rolled sheet is frequently used from the viewpoint of reducing the weight of the vehicle body. By the way, since car body sheets are used after being pressed, it is required that they have excellent molding processability, that there are no Ruders marks during molding, and that they have adequate strength. Thus, since it is usually used after being baked, it is required to obtain an appropriate strength after baking. Of course, it is required that the moldability is good, but as a body sheet for an automobile, hem processing (bending processing) is used for joining and integrating the outer panel and the inner panel. Since it is often used after being subjected to one type), it is strongly desired that the hemmability is particularly excellent among the moldability.

  Conventionally, as an aluminum alloy for an automobile body sheet, in addition to an Al—Mg alloy, an Al—Mg—Si alloy or an Al—Mg—Si—Cu alloy having aging properties is mainly used. . These aging Al-Mg-Si alloys and aging Al-Mg-Si-Cu alloys have relatively low strength and excellent formability during molding before coating baking, while coating baking. In addition to the advantage that it is aged by heating at the time and the strength after baking is increased, it also has the advantage that the Ruders mark is less likely to occur.

As the prior art relating to the bending workability improvement, such hemmability, particle size and the number of Mg ₂ Si compound or grain boundary precipitates, Patent Document 1 and Patent Document that controls the dispersion density of the second phase particles 2 and the techniques of Patent Document 3 and Patent Document 4 that regulate the proportion of crystal grain boundaries whose orientation difference between crystal grain boundaries is 15 ° or less or 20 ° or less, or the {200} plane or {400 of the texture. } There are Patent Document 5 and Patent Document 6 that regulate the integrated intensity of the surface. The inventors have already made proposals shown in Patent Documents 7 and 8.

JP 2003-105471 A JP 2003-268472 A JP2003-171726 JP 2003-166029 A JP 2003-226926 A JP2003-226927A JP 2003-268475 A JP 2004-323952 A

  The plate obtained by the conventional manufacturing method using the aging Al-Mg-Si-based and Al-Mg-Si-Cu-based alloy plates for automobile body seats as described above is required for recent automobile body seats. It has been difficult to fully satisfy the properties obtained.

  That is, recently, in order to further reduce the cost and further improve the material, there has been a strong demand for the development of a technology for manufacturing an automobile body seat at a low cost while having higher performance than before. However, while satisfying various required performances such as moderate strength and formability (especially heme workability) and room temperature aging suppression performance while achieving low cost, it can be obtained by conventional conventional manufacturing methods. Al-Mg-Si-based and Al-Mg-Si-Cu-based alloy plates are still insufficient.

  Here, the simplest way to reduce costs is to omit a part of the manufacturing process. However, simply omitting a part of the conventional manufacturing process can reduce the cost. Of course, some of the performance may be degraded.

  Here, since the forming process, particularly the hem process, is a severe bending process of 180 ° bending with a bending inner diameter of 1 mm or less, it is difficult to achieve both good hem processability and press formability. In particular, it was extremely difficult to achieve both good hemmability and press formability at low cost without impairing other performance.

  Furthermore, in the conventional manufacturing method, it is indispensable to perform cold rolling in order to refine crystal grains between hot rolling and solution treatment, and this has also been an obstacle to cost reduction.

  Also, with regard to paint baking, from the viewpoints of energy saving and productivity improvement, and combined use with materials such as resins that are not preferred to be exposed to high temperatures, recently, the baking temperature has been made lower than before and baking has been performed. There is an increasing tendency to shorten the time. However, in the case of aging Al-Mg-Si-based and Al-Mg-Si-Cu-based alloy plates obtained by a conventional general manufacturing method when the strength after coating baking is important, low-temperature and short-time coating baking In the treatment, there is a problem that curing at the time of coating baking (baking curing) is insufficient, and it becomes difficult to obtain sufficient high strength after baking.

  On the other hand, aluminum alloy sheets used for automobile inner panels may not necessarily require high strength after paint baking. In this case, higher formability is required instead of high strength. However, in the case of aging Al-Mg-Si-based and Al-Mg-Si-Cu-based alloy plates obtained by a conventional general manufacturing method, there is a problem that such high formability requirements cannot be satisfied. There is.

  That is, in the aging Al-Mg-Si-based and Al-Mg-Si-Cu-based alloy plates obtained by a conventional general manufacturing method, when left at room temperature after the plate production, hardening is likely to occur due to natural aging. For this reason, there is a problem that moldability, particularly hemmability, tends to be hindered.

Of the above-mentioned patent documents, in Patent Documents 1 and 2, the compound dispersion state, particularly the particle size and number of Mg ₂ Si, or the grain boundary precipitates are controlled by the regulation such as the homogenization treatment and the subsequent cooling rate. Although it has been proposed to improve the bending workability by adjusting the dispersion state of the second phase particles, etc., in the methods of these Patent Documents 1 and 2, the compound dispersion state is adjusted as described above. Even so, it has been difficult to fully satisfy the recent strict requirements for bendability. In either case, a cold rolling process is necessary, and the manufacturing cost is inevitably high.

  On the other hand, in Patent Document 3 and Patent Document 4, it is proposed to improve bending workability by regulating the ratio of crystal grain boundaries in which the orientation difference between crystal grains is 15 ° or less or 20 ° or less. In Patent Document 5 and Patent Document 6, it is proposed that the integrated strength of the {200} plane and the {400} plane is regulated to improve flat hem workability as texture control. In Patent Document 7 by humans and others, it is proposed to improve the hem workability by regulating the cube orientation density, the ND rotating cube orientation density, and the ear rate. Certainly, with these proposed methods, a certain degree of improvement in bending workability can be achieved, but as a result of further experiments and examinations by the present inventors, any direction of the rolled sheet can be obtained with either method. It was found that not all the bendability was improved. For example, even if the bendability in the direction parallel to the rolling direction or the direction perpendicular to the rolling direction is improved, the bendability in the direction of 45 ° with respect to the rolling direction is not improved. It turns out that the problem of gender arises.

  Regarding the above bending anisotropy, Patent Document 8 by the present applicant proposes a method for improving the bending anisotropy by controlling the cube orientation density in the plate thickness direction. Although this improvement method is surely effective, it is not sufficient yet, and since a cold rolling process is necessary, there is a drawback that the manufacturing cost is high.

  This invention was made against the background described above, has moderate bake hardenability, has an appropriate increase in strength during paint baking, and changes over time at room temperature after plate production. Even when left for a long period of time, there is little decrease in formability due to hardening due to natural aging. Furthermore, it has good formability, especially good bendability (especially heme workability) and bending anisotropy. To provide an aluminum alloy sheet for forming that has low properties and a method for manufacturing such an aluminum alloy sheet for forming that has such excellent performance reliably and stably at a low cost on a mass production scale. It is intended.

  As a result of repeated experiments and examinations by the present inventors to solve the above-mentioned problems, as a structure of the final plate of Al-Mg-Si-based or Al-Mg-Si-Cu-based alloy, a specific orientation, In particular, while increasing the crystal orientation density of the cube orientation (cube orientation), not only the cube orientation but also the {011} <211> orientation density, {123} <634> orientation density, and {112} <111> orientation density By appropriately regulating the total of the above, bending workability, particularly hemming workability can be improved without impairing press workability, and the anisotropy (bending anisotropy) can be reduced. It was also found that appropriate bake hardenability and room temperature aging resistance can be obtained. Further, the present inventors have found a process condition capable of manufacturing an aluminum alloy sheet for forming having such excellent performance on a mass-production scale reliably, stably and at low cost, and has made the present invention.

  Specifically, the aluminum alloy sheet for forming according to the invention of claim 1 is made of an aluminum alloy made of an Al—Mg—Si or Al—Mg—Si—Cu alloy, and the cube orientation density is random. More than 10 times the sample having a crystal orientation, and the sum of the orientation densities of the {011} <211>, {123} <634>, and {112} <111> orientations It is 4 times or more, and further, 0 °, 90 ° ear ratio is 5% or more, and the crystal grain size is 4 or more by ASTM number.

  The aluminum alloy sheet for forming according to the invention of claim 2 contains Mg 0.2 to 1.5%, Si 0.3 to 2.0%, Mn 0.03 to 0.6%, Cr 0.01 to One or two selected from 0.4%, Zr 0.01-0.4%, Fe 0.03-0.5%, Ti 0.005-0.2%, Zn 0.03-2.5% It contains more than seeds, Cu is controlled to 2.0% or less, the balance is made of an aluminum alloy consisting of Al and inevitable impurities, and the cube orientation density is 10 times or more that of a sample having a random crystal orientation. And the sum of the orientation densities of the {011} <211>, {123} <634>, and {112} <111> orientations is at least four times that of a sample having a random crystal orientation, and is further 0 °. 90 ° ear rate is 5% or more, grain size is ASTM 4 or more.

  Furthermore, the manufacturing method of the aluminum alloy plate for forming according to the invention of claim 3 is the homogeneous treatment at 480 ° C. or higher with respect to the ingot when the aluminum alloy plate for forming according to claim 1 or claim 2 is manufactured. After cooling, it is cooled, and then hot rolling is started at a temperature of 300 ° C. or higher, hot rolling is performed up to the thickness of the final product plate, and the hot rolling is finished at a temperature within a range of 100 to 350 ° C. The obtained hot-rolled sheet is subjected to a solution treatment at a temperature of 480 ° C. or higher and cooled to room temperature at an average cooling rate of 100 ° C./min or higher.

  Furthermore, the method for producing an aluminum alloy plate for forming according to the invention of claim 4 is the method for producing an aluminum alloy plate for forming according to claim 3, wherein after the solution treatment, an average of 100 ° C./min or more is obtained. It is characterized by cooling to a temperature of 50 ° C. or more and less than 150 ° C. at a cooling rate, and subsequently performing a stabilization treatment for 1 hour or more within this temperature range.

  And the manufacturing method of the aluminum alloy plate for shaping | molding of invention of Claim 5 is a manufacturing method of the aluminum alloy plate for shaping | molding processing of Claim 3, After the said solution treatment, it is an average of 100 degrees C / min or more. After cooling to a temperature of less than 50 ° C. at a cooling rate, and then allowing to stand at room temperature, stabilization treatment is performed for 1 hour or more within a temperature range of 50 ° C. or more and less than 150 ° C.

  The aluminum alloy sheet for forming according to the present invention has excellent formability, particularly hemmability, has little bending anisotropy, and can appropriately adjust strength after baking, and changes with time at room temperature. Therefore, it is most suitable for automotive body seats that are used after press coating or hem processing. In addition, according to the method for manufacturing a forming aluminum alloy plate of the present invention, the forming alloy alloy plate having excellent performance as described above can be manufactured reliably and stably at a low cost even on a mass production scale. Can do.

  The aluminum alloy plate for forming according to the present invention may basically be an Al-Mg-Si alloy or an Al-Mg-Si-Cu alloy, and its specific composition is not particularly limited. Although not usually, an alloy having a component composition as defined in claim 2, that is, Mg 0.2-1.5%, Si 0.3-2.0%, and Mn 0.03-0.6%, Selected from Cr 0.01-0.4%, Zr 0.01-0.4%, Fe 0.03-0.5%, Ti 0.005-0.2%, Zn 0.03-2.5% It is preferable to use an aluminum alloy containing one or two or more kinds, further Cu being regulated to 2.0% or less, and the balance being Al and inevitable impurities.

  The reason for limiting the component composition of the material alloy defined in claim 2 will be described.

Mg:
Mg is an alloy element that is a basic alloy of the system targeted by the present invention, and contributes to strength improvement in cooperation with Si. If the amount of Mg is less than 0.2%, G. contributes to strength improvement by precipitation hardening during baking. P. Since the amount of zone formation decreases, sufficient strength improvement cannot be obtained. On the other hand, if it exceeds 1.5%, coarse Mg-Si based intermetallic compounds are generated, which is disadvantageous for increasing cube orientation density. Further, since the formability, particularly the bending workability is lowered, the amount of Mg is set in the range of 0.2 to 1.5%. In order to improve the formability of the final plate, particularly bending workability, the Mg content is preferably in the range of 0.3 to 0.9%.

Si:
Si is also an alloy element that is fundamental in the alloy of the present invention, and contributes to strength improvement in cooperation with Mg. In addition, Si is produced as a crystallized product of metal Si at the time of casting, and the periphery of the metal Si particles is deformed by processing and becomes a recrystallization nucleus generation site during solution treatment. It also contributes to If the amount of Si is less than 0.3%, the above effects cannot be obtained sufficiently. On the other hand, if it exceeds 2.0%, coarse Si particles and coarse Mg-Si intermetallic compounds are produced, and the cube orientation density is reduced. It is disadvantageous to increase, and the formability, particularly bending workability, is reduced. Therefore, the Si amount is set in the range of 0.3 to 2.0%. In order to obtain a better balance between press formability and bending workability, the Si content is preferably in the range of 0.5 to 1.3%.

Mn, Cr, Zr, Fe, Ti, Zn:
These elements are effective for improving the strength, refining crystal grains, improving aging (bake hardenability), and improving surface treatment properties, and one or more of these elements are added. Among these, Mn, Cr, and Zr are elements that are effective in improving the strength, refining crystal grains, and stabilizing the structure. However, the Mn content is less than 0.03% or the Cr content is less than 0.03. If the content is less than 01% or the content of Zr is less than 0.01%, the above effects cannot be obtained sufficiently, while the content of Mn exceeds 0.6%, or the contents of Cr and Zr are respectively If it exceeds 0.4%, not only the above effects are saturated, but also a large number of intermetallic compounds may be produced, which may adversely affect moldability, particularly hemmability, and therefore Mn is 0.03 to 0. Within the range of 0.6%, Cr and Zr were each within the range of 0.01 to 0.4%. Fe is also an element effective for strength improvement and grain refinement, but if its content is less than 0.03%, sufficient effects cannot be obtained, while if it exceeds 0.5%, the cube orientation density is increased. There is a disadvantage in that the moldability, particularly the bending workability, may be lowered, and therefore the Fe content is set in the range of 0.03 to 0.5%. Furthermore, Ti is an element effective for improving the strength and refining the ingot structure, but if its content is less than 0.005%, a sufficient effect cannot be obtained, while if it exceeds 0.2%, the effect of adding Ti In addition to being saturated, there is a possibility that coarse crystallized matter may be formed, so the Ti content is set in the range of 0.005 to 0.2%. Zn is an element that contributes to improvement of strength through improvement of aging and is effective for improvement of surface treatment. However, if the amount of Zn is less than 0.03%, the above effect cannot be obtained sufficiently. If the content exceeds 5%, the moldability deteriorates, so the Zn content is set in the range of 0.03 to 2.5%.

Cu:
Cu is an element that may be added to improve strength and formability, but if its amount exceeds 1.5%, corrosion resistance (intergranular corrosion resistance, yarn rust resistance) deteriorates. The Cu content was regulated to 2.0% or less. In addition, when it is desired to further improve the corrosion resistance, the Cu content is preferably 1.0% or less, and when the corrosion resistance is particularly important, it is desirable to regulate the Cu content to 0.05% or less.

  In addition to the above elements, basically, Al and inevitable impurities may be used.

  In addition, said Mn, Cr, Zr, Fe, Ti, Zn content range is shown as the range in the case of adding each positively, and the case where all contain less than a lower limit as an impurity. It is not excluded. In particular, Fe of less than 0.03% is usually inevitably contained if a normal aluminum ingot is used.

  In addition, in an aging Al—Mg—Si alloy or an aging Al—Mg—Si—Cu alloy, a trace amount of Ag, In, Cd, Be, or Sn which is a high temperature aging promoting element or a room temperature aging inhibiting element is added. However, even in the case of the present invention, addition of these elements is permissible as long as it is added in a trace amount.

  In addition, in general Al alloys, B may be added simultaneously with the above-mentioned Ti to refine the ingot structure. By adding B together with Ti, the ingot structure is refined and stabilized. The effect becomes more prominent. In the case of this invention, it is permissible to add 500 ppm or less of B together with Ti.

  Furthermore, it is said that the addition of V and Sc is effective for refining the ingot structure. In the case of this invention, a small amount of V or Sc may be added. If it is in the range of Sc 0.01 to 0.2%, there is no particular problem.

  Furthermore, in the aluminum alloy sheet for forming according to the present invention, in order to obtain good bending workability, particularly good hemming workability, and at the same time to suppress bending anisotropy, the alloy composition is set as described above. In addition to adjustment, it is extremely important to appropriately suppress the texture of the final aluminum alloy sheet, particularly the crystal orientation density.

  Here, in the present invention, the crystal orientation density of the final plate is regulated not only for controlling the grain boundary property (small angle or large angle) but also for the slip of crystals accompanying plastic deformation of the aluminum alloy. Its main purpose is to control the entire deformation. In particular, it is extremely important to increase the degree of accumulation of crystal orientations that are likely to cause cross-slip during bending. By doing so, the increase in dislocation density due to processing is suppressed, and work hardening is suppressed. Is possible. Further, as a result, during hem processing, large strain deformation of the material is possible until the crack limit strength is reached by suppressing work hardening. Here, in order to make the slip deformation behavior greatly different from that of a conventional material having a relatively random crystal orientation, in other words, a conventional material that hardly causes cross-slip, it is necessary to accumulate crystal orientations. On the other hand, there are various crystal orientations in the actual material, but as a result of extensive studies by the present inventors, the orientation density of the cube orientation, that is, the ideal orientation of the cube orientation, in particular, among the various crystal orientations ( 001) It has been found that by increasing the orientation density of the <100> orientation, the sliding deformation behavior can be made significantly different from that of the conventional material. That is, by increasing the cube orientation density, cross-sliding during work deformation becomes active, work hardening is suppressed, and bending workability is improved.

  On the other hand, if the cube orientation density is simply increased, the bending anisotropy is rather prominent and the balance of material properties may be reduced. Therefore, the present inventors conducted further experiments and examinations. As a result, not only the cube orientation density was increased, but also the {011} <211> orientation, {123} <634> orientation, and {112} < It has been found that by properly regulating the total crystal orientation density of the 111> orientation and the above three orientations, the bending workability can be improved and the bending anisotropy can be reliably and stably reduced.

  That is, by making the total of the above {011} <211> orientation, {123} <634> orientation, and {112} <111> orientation at least four times that of a sample having a random crystal orientation, The bending anisotropy can be improved at the same time.

  Here, in the present invention, not only the cube orientation density is regulated, but also the sum of the orientation densities of {011} <211> orientation, {123} <634> orientation, and {112} <111> orientation is regulated. The reason for this is to reduce the bending anisotropy caused by the cube orientation.

  Further, in the aluminum alloy plate for forming according to the present invention, it is also important that the ear rate of the 0 ° ear and the 90 ° ear is 5% or more over the entire plate. That is, as described above, in the present invention, in order to ensure good bending workability and suppress bending anisotropy, cube orientation density and {011} <211> orientation, {123} <634> orientation, { 112} The total orientation density of <111> orientations is defined, but the orientation density of other crystal orientations also affects bending workability to some extent. However, in practice, it is difficult to strictly define the orientation density of all crystal orientations other than these orientations. On the other hand, the crystal orientation of the material can be macroscopically evaluated based on the ear ratio of the cup squeezed by the plate cupping test. Therefore, in the present invention, the influence of the orientation density of the crystal orientation other than the cube orientation and the above-mentioned three orientations is evaluated and regulated by the 0 ° ear and the 90 ° ear. Specifically, the 0 ° of the cup based on the rolling direction, the 90 ° ear ratio is less than 5%, even if the above-mentioned cube orientation density and the above-mentioned total orientation density of the three orientations are satisfied, Good bending workability and bending anisotropy may not be obtained. Therefore, in the present invention, the ear rate is regulated as described above. The 0 ° and 90 ° ear ratios are particularly preferably 10% or more even within the above range.

  Further, in the aluminum alloy plate for forming according to the present invention, the crystal grain size needs to be 4.0 or more in terms of ASTM number, preferably 6.0 or more in terms of ASTM number. That is, in order to improve the bending workability and prevent rough skin (appearance defects) during press molding, it is necessary to make the crystal grain size fine, and the crystal grain size is 4.0 or more, preferably 6. By setting it to 0 or more, it is possible to improve the bending workability and to prevent appearance defects due to rough skin during press molding.

  Next, a method for producing the aluminum alloy plate for forming according to the present invention will be described.

  First, an alloy having the above-described component composition is melted according to a conventional method, and cast by a normal casting method such as a DC casting method.

  The resulting ingot is homogenized at a temperature of 480 ° C. or higher. The reason why the conditions for the homogenization treatment are defined in this way is as follows.

  In other words, the homogenization treatment has the effect of removing segregation of the additive elements in the ingot, and dissolving the coarse second phase particles and crystallized substances present at the boundaries between the ingot cells and crystal grains in the matrix. In addition, it is an important process for obtaining a required crystal orientation by organically coupling with a reduction in performance variation of the product plate and further organically connecting with a hot rolling process and a solution treatment process. If the homogenization temperature is less than 480 ° C., the above-described effects are insufficient. The upper limit of the homogenization treatment temperature is not particularly limited, but treatment at 590 ° C. or lower is preferable in order to avoid eutectic melting. In addition, the time for the homogenization treatment is not particularly specified, but usually 1 to 24 hours is desirable.

Although hot rolling is performed after the homogenization treatment, this hot rolling needs to be performed so as to satisfy the following conditions (1) to (3).
(1) The hot rolling start temperature is 300 ° C or higher.
(2) The hot rolling end temperature is in the range of 100 to 350 ° C.
(3) Rolling to the required final thickness (product thickness) by hot rolling. Therefore, do not perform cold rolling after hot rolling.

  First, the condition (1), that is, setting the hot rolling start temperature to 300 ° C. or higher is an indispensable condition for ensuring the productivity of hot rolling and preventing edge cracking. If the hot rolling start temperature is less than 300 ° C., the hot rolling itself becomes difficult, and not only the productivity is lowered, but also there is a risk of edge cracking. The upper limit of the hot rolling start temperature is not particularly limited, but it is usually desirable to set the temperature to 590 ° C. or lower in order to avoid eutectic melting. In addition, when emphasizing surface quality and refinement of the hot rolled structure, it is preferable to set the hot rolling start temperature within a range of 340 to 550 ° C.

  The condition (2) is an indispensable condition for controlling the recrystallization of the material during hot rolling in combination with the condition (1) to obtain a required crystal orientation density. Further, in the process of the present invention in which the cold rolling process is not performed, it is extremely important to keep the hot rolling end temperature low and store hot strain in order to refine the crystal grains during the solution treatment. . If the hot rolling end temperature is less than 100 ° C., the plate surface quality is deteriorated. On the other hand, if the hot rolling end temperature exceeds 350 ° C., the crystal grains may be coarsened during the solution treatment. It was set within the range of 350 ° C. When emphasizing plate surface quality and crystal grain refinement, it is preferable to set the hot rolling end temperature within the range of 180 to 280 ° C.

  The condition (3) is also extremely important for the present invention. In the process of this invention, on the premise that the required final plate thickness (product plate thickness) is obtained by hot rolling, the final plate can be obtained by performing solution treatment immediately after hot rolling without cold rolling. is important. Moreover, it is possible to easily obtain a predetermined cube orientation density and the total orientation density of the three orientations by directly solution-treating the hot-rolled sheet without cold rolling. And since a cold rolling process is not required, productivity is high and the reduction of the manufacturing cost of material is obtained.

  Here, if any one of the above hot rolling conditions is not satisfied, it is difficult to obtain a final plate that satisfies a required crystal orientation density condition, and various properties of the final plate may be deteriorated.

After obtaining the required plate thickness as described above, solution treatment is immediately performed at a temperature of 480 ° C. or higher without performing cold rolling. This solution treatment is an important process for solid-dissolving Mg ₂ Si, elemental Si, etc. in the matrix, thereby imparting bake hardenability and improving the strength after baking. This process also contributes to lowering the distribution density of the second phase particles by solid solution of Mg ₂ Si, simple substance Si particles, etc., improving ductility and bendability, and finally by recrystallization. This is an important process for obtaining a desired crystal orientation and obtaining good formability (bending workability, bending anisotropy, press formability).

When the solution treatment temperature is less than 480 ° C., it is considered advantageous for suppressing the change over time at room temperature, but in this case, the amount of solid solution of Mg ₂ Si, Si, etc. is reduced and sufficient bake hardenability is obtained. Not only cannot be obtained, but ductility and bendability are also deteriorated, so the solution treatment temperature must be 480 ° C. or higher. In particular, when emphasizing the solution effect, the solution treatment temperature is preferably 500 ° C. or higher. On the other hand, the upper limit of the solution treatment temperature is not particularly specified, but it is usually desirable to set the temperature to 580 ° C. or lower in consideration of eutectic melting and recrystallization grain coarsening. The solution treatment time is not particularly limited, but usually the solution treatment effect is saturated if it exceeds 5 minutes, and not only the economic efficiency is impaired, but also the crystal grain coarsening may occur. Within 5 minutes is desirable.

After the solution treatment, cooling (quenching) is performed at a cooling rate of 100 ° C./min or more. Here, if the cooling rate after the solution treatment is less than 100 ° C./min, Mg ₂ Si or simple substance Si precipitates in the grain boundary during cooling, and at the same time, the formability, in particular the heme workability decreases, The bake hardenability is lowered, and a sufficient improvement in strength during paint baking cannot be expected.

  The cooling at a cooling rate of 100 ° C./min or higher after the solution treatment at a temperature of 480 ° C. or higher as described above may be performed to room temperature (room temperature; usually less than 50 ° C.). That is, particularly in applications where the strength after baking and the aging resistance at room temperature are not so strict, when manufacturing costs are important, after solution treatment, at a cooling rate of 100 ° C./min or more at room temperature (room temperature It is only necessary to reduce the cost by applying a simple process of cooling to).

  However, normally, as defined in claim 4, after solution treatment at a temperature of 480 ° C. or higher, cooling to a temperature range of 50 ° C. or higher and lower than 150 ° C. at a cooling rate of 100 ° C./min or higher ( It is desirable to perform the stabilization treatment within the temperature range (less than 50 to 150 ° C.) before the temperature is lowered to a temperature range (room temperature) less than 50 ° C. after quenching. In this stabilization treatment, the holding time in the temperature range of less than 50 to 150 ° C. is usually preferably maintained for 1 hour or longer, and may be cooled (slowly cooled) over 1 hour or longer within the temperature range. .

  The reason for performing the stabilization treatment at a temperature of 50 to less than 150 ° C. without cooling to a temperature range of less than 50 ° C. after the solution treatment and quenching to a temperature range of less than 50 to 150 ° C. is as follows. Street.

  That is, after solution treatment, a room temperature cluster is generated particularly when cooling to room temperature below 50 ° C. at an average cooling rate of 100 ° C./min or more. This room temperature cluster contributes to strength. P. Since it is difficult to shift to the zone, it is disadvantageous for paint bake hardenability. On the other hand, when the solution is cooled to a temperature range of 150 ° C. or higher and kept as it is after the solution treatment, P. Zones or stable phases are generated, the strength of the material before molding becomes too high, and the formability such as hem bendability and press working deteriorates. Therefore, it is desirable to perform solution treatment-quenching-stabilization treatment under the above conditions from the viewpoint of balance between hemmability, press workability, paint bake hardenability, and room temperature aging resistance.

  In applications where paint bake curability is not particularly required, or in applications where the bake hardenability is actively suppressed while emphasizing improvement in aging resistance and press formability, 100 ° C / After quenching to a temperature range of less than 50 ° C. at a cooling rate of min or more, and holding at room temperature (room temperature), a stabilization treatment for 1 hour or more may be performed again at a temperature range of less than 50 to 150 ° C. In this case, the room temperature holding period before the stabilization treatment is not particularly defined, but it is usually preferably within 15 days from the viewpoint of productivity.

  Examples of the present invention will be described below together with comparative examples. The following examples are for explaining the effects of the present invention, and the processes and conditions described in the examples do not limit the technical scope of the present invention.

  Alloys of alloy symbols A1 to A4 within the component composition range of the present invention shown in Table 1 were melted in accordance with conventional methods and cast into slabs by DC casting.

  Each obtained slab was homogenized at 550 ° C. for 6 hours. After the homogenization treatment, it was subjected to hot rolling. The hot rolling conditions are shown in production process numbers 1 to 8 in Table 2. Moreover, since the microstructure was investigated with the optical microscope about each obtained hot rolled sheet, the result is also shown in Table 2.

  Further, the treatment shown in Table 3 was performed on each hot-rolled sheet. That is, a solution treatment is performed as it is without performing a cold rolling on a hot-rolled sheet, or a solution treatment is performed after performing a cold rolling, and further a stabilization treatment is performed after the solution treatment ( However, some of them are not stabilized.) The cooling (quenching) speed after solution treatment is about 220 ° C./min. Here, production process numbers 1 and 8 are examples in which quenching after solution treatment was performed to a temperature of less than 50 ° C. (room temperature) and then stabilization treatment was not performed, and production process numbers 2, 3, 5 , 6 is an example in which quenching after solution treatment is limited to a temperature range of 50 ° C. or more and less than 150 ° C., followed by stabilization treatment. Further, manufacturing process numbers 4 and 7 are quenching after solution treatment. This is an example in which the stabilization treatment was performed again after the temperature was lowered to less than 50 ° C. and left at room temperature.

  The texture (crystal orientation density) of each aluminum alloy plate (product plate) finally obtained as described above was examined as follows.

  That is, a 1 mm thick plate etched with a NaOH aqueous solution from the surface toward the center of the plate thickness to a depth of ¼ plate thickness was used as a measurement sample. The incomplete pole figures of {100}, {110}, and {111} were measured by the X-ray diffraction Schertz reflection method, and based on these, three-dimensional crystal orientation analysis (ODF) was performed and examined. In these analyses, the data obtained by measuring a sample having a random crystal orientation made from aluminum powder is used as a standardized file for analysis of {100}, {110}, {111} pole figures. Thus, the ideal orientation of the cube {001} <100>, {011} <211>, {123} <634>, {112} <111> orientation density belonging to the rolling texture as multiples of the sample having a random orientation Asked. In general, since there is azimuth dispersion having a certain angle centered on the azimuth, in the present invention, the maximum azimuth density in the 15 ° rotation range around the azimuth is taken and a representative value of the azimuth density is obtained. did. In this invention, the crystal orientation density is all based on three-dimensional crystal orientation analysis (ODF).

  Further, each final plate obtained as described above was allowed to stand at room temperature for 30 days and 180 days after production in consideration of room temperature aging, and after 2% stretching, 170 ° C. × 20 minutes baking (baking). Each plate before and after baking is subjected to a tensile test in each direction of 0 °, 45 °, and 90 ° with respect to the rolling direction (RD), and the mechanical strength is 0.2% proof stress in each direction. The value was measured. Similarly, for the plate before baking, the ear rate was examined by a cup squeeze test, the hem workability was evaluated by a hem processing test, and the overhang height was measured by a punch overhang test.

  Here, the specific method of each test is shown below.

Final grain size:
The ASTM number was measured based on an image mapped by the EBSP (EBSD) method in a cross section parallel to the rolling direction of the plate. In this determination, a boundary line with a misorientation of 5 ° or more was regarded as a crystal grain boundary.

Ear rate measurement:
After the lubricating oil was applied to the plate, the cup was squeezed under the conditions of a punch diameter of 32 mm, a blank diameter of 62 mm, and a wrinkle presser of 100 kg, and the ear ratio of the cup was examined. Here, the direction of the ear rate is indicated by a 0 ° direction and a 90 ° direction based on the rolling direction.

Hem processability evaluation:
Bending specimens are collected in the direction of 0 °, 45 °, 90 ° 3 in the plate surface with respect to the rolling direction (RD) of the material, stretched 7%, then tightly bent at 180 ° and visually cracked. The presence or absence of occurrence was observed. Here, a circle indicates that there is no crack, and a cross indicates that there is a crack.

Overhang test:
A masking film was pasted on both sides of a 1 mm plate having a size of 200 mm × 200 mm, and in order to further improve lubrication, it was subjected to a bulge test in a state where wax was applied, and the maximum bulge height was examined. A punch having a ball head punch diameter of 100 mm was used.

  The above measurement results and test results are shown in Tables 4 and 5.

  Production process numbers 1 to 5 are all within the range defined by the present invention for the alloy component composition, and the production process conditions are also within the range defined by the present invention. The conditions specified in this invention are satisfied. In these cases, it is confirmed that hemmability is excellent, appropriate bake hardenability is obtained, the overhang height is high, and the bending anisotropy is small. It was done.

  On the other hand, in the production process numbers 6 to 8, the alloy component composition is within the range specified in the present invention, but any of the production process conditions is out of the scope of the present invention, and the crystal orientation density, the crystal grain size condition Or the like did not satisfy the conditions defined in the present invention. Among these, in the case of production process number 6, the crystal grain size was coarse, the hemmability was inferior, and the overhang height was low. In the case of manufacturing process number 7, there was bending anisotropy, the hemmability in the 45 ° direction was inferior, and the overhang height was low. In the case of production process number 8, fine rolling was performed because cold rolling was performed, but not only the ridging resistance was poor, but the hemming property was inferior, and the overhang height was also low.

Claims (5)

  An aluminum alloy made of an Al—Mg—Si-based or Al—Mg—Si—Cu-based alloy is used as a material, and the cube orientation density is 10 times or more that of a sample having a random crystal orientation, and the {011} <211> orientation And the sum of each orientation density of {123} <634> orientation and {112} <111> orientation is 4 times or more that of a sample having a random crystal orientation, and further, 0 °, 90 ° ear ratio is 5% or more, An aluminum alloy plate for forming, wherein the crystal grain size is 4 or more in terms of ASTM number.   Mg 0.2-1.5% (mass%, the same shall apply hereinafter), Si 0.3-2.0%, Mn 0.03-0.6%, Cr 0.01-0.4%, Zr0.01 -0.4%, Fe0.03-0.5%, Ti0.005-0.2%, Zn containing 0.03-2.5%, 1 type or 2 types or more are contained, and also Cu Is controlled to 2.0% or less, the balance is made of an aluminum alloy composed of Al and inevitable impurities, the cube orientation density is 10 times or more that of a sample having a random crystal orientation, and {011} <211> The sum of the orientation density of the orientation, {123} <634> orientation, and {112} <111> orientation is at least four times that of the sample having a random crystal orientation, and the 0 ° and 90 ° ear ratios are 5% or more. The crystal grain size is ASTM number 4 or more. An aluminum alloy plate for forming. In producing the aluminum alloy sheet for forming according to claim 1 or 2,
The ingot is subjected to a homogenous treatment at 480 ° C. or higher, then cooled, and then hot rolling is started at a temperature of 300 ° C. or higher, and hot rolling is performed until the final product plate thickness reaches 100 to 350 ° C. The hot rolling is terminated at a temperature within the range of, and the obtained hot rolled sheet is subjected to a solution treatment at a temperature of 480 ° C. or higher and cooled to room temperature at an average cooling rate of 100 ° C./min or higher. A method for producing an aluminum alloy plate for forming, characterized in that In the manufacturing method of the aluminum alloy plate for shaping | molding of Claim 3,
After the solution treatment, it is cooled to a temperature of 50 ° C. or higher and lower than 150 ° C. at an average cooling rate of 100 ° C./min or higher, and then a stabilization treatment is performed for 1 hour or longer within this temperature range. The manufacturing method of the aluminum alloy plate for shaping | molding processing. In the manufacturing method of the aluminum alloy plate for shaping | molding of Claim 3,
After the solution treatment, after cooling to a temperature of less than 50 ° C. at an average cooling rate of 100 ° C./min or more, and then allowing to stand at room temperature, stable for 1 hour or more within a temperature range of from 50 ° C. to less than 150 ° C. The manufacturing method of the aluminum alloy plate for shaping | molding processing characterized by performing a heat treatment.