JP5367250B2 - Aluminum alloy plate for forming and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an Al alloy sheet for forming-coating and baking which is small in bending anisotropy, and elongation anisotropy, is satisfactory in the balance of press formability and bending workability, is excellent in ridging resistance, allows impartation of satisfactory baking hardenability, and high press formability, and is small in ambient temperature aging. <P>SOLUTION: The Al alloy sheet is made from Al-Mg-Si-based or Al-Ag-Si-Cu-based alloy as a raw material, and satisfies D1&gt;60, D2&gt;5, D2/D3&gt;1.2, D4&gt;5, when a cube orientation density is defined as D1, ND rotary cube orientation density as D2, a Goss orientation density as D3, and total of Cu, S, Bs orientation densities as D4, 0, and 90&deg; ear rate as &ge;3% and a crystal grain size ASTM No. &ge;4.5. Aa a manufacturing method, the Al alloy sheet is manufactured under conditions of performing cooling, after homogenization treatment, by rapid cooling at &ge;100&deg;C/h down to a temperature area of &ge;150 and &lt;450&deg;C, then in succession, allowing the sheet to stand for &ge;0.5 hour in this temperature area, and further subjecting the sheet to hot rolling at starting temperature of &le;460&deg;C at &ge;1 times of passes of &ge;40% in rolling rate in a stage of a sheet thickness 200 to 20 mm, then to cold rolling of &ge;30% without annealing and to solution heat treatment. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to parts and parts of various automobiles, ships, aircraft, etc., such as automobile body seats and body panels, or building materials, structural materials, various other machinery and equipment, home appliances, parts thereof, and the like. The present invention relates to an Al-Mg-Si-based or Al-Mg-Si-Cu-based aluminum alloy plate used by baking and a method for producing the same, and has low bending anisotropy and strength anisotropy, and press formability. The balance of bending workability is good, especially ridging resistance is excellent without intermediate annealing, and good bake hardenability and high press formability can be imparted depending on the application. The present invention relates to an aluminum alloy plate for forming and a method for producing the same with little change.

  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, automobile body sheets are used after being pressed, so that they have excellent molding processability, and are used with hem bending to join and integrate the outer panel and inner panel. Therefore, it is required that the hemmability is excellent among the moldability. In addition, it is also required that no Luders mark, ridging mark, and rough skin occur during molding. In addition, since it is usually used after painting and baking, when emphasizing strength in the balance between moldability and strength, high strength can be obtained after painting and baking, conversely, emphasizing moldability. In some cases, high press formability is required even if the strength after baking is slightly sacrificed. And since an aluminum alloy rolled sheet is expensive compared with a steel plate, low-cost manufacturing technology is strongly demanded.

  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.

In addition, as a prior art regarding bending workability improvement, such as hem bendability, the technique of patent document 1 which controls the particle size and number, etc. of a Mg-Si type compound, and the crystal | crystallization whose orientation difference of a grain boundary is 15 degrees or less There is a technique of Patent Document 2 that regulates the ratio of grain boundaries.
JP 2002-356730 A JP 2003-171726 A

  In the plate obtained by the conventional manufacturing method for the aging Al-Mg-Si-based and Al-Mg-Si-Cu-based alloy plates for automobile body sheets as described above, it is required for the recent automobile body sheets. 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 aiming at low cost, strength and formability (especially press formability, hem bendability), bake hardenability (age hardening, ie, BH property), suppression of ridging marks, room temperature deterioration with time, corrosion resistance The Al—Mg—Si-based and Al—Mg—Si—Cu-based alloy plates obtained by the conventional general manufacturing method are still insufficient for satisfying various required performances.

  Here, as a cost reduction measure, it is easiest to omit a part of the manufacturing process, but even if a part of the conventional manufacturing process is simply omitted, the cost can be reduced. Of course, there is a concern about a decrease in some of these performances.

  Here, the molding process, particularly the hem bending process, is a severe bending process of 180 ° bending with a bending inner diameter of 1 mm or less, and thus it is difficult to achieve both good hem bendability and press formability. There is a problem, and it has been extremely difficult to suppress the occurrence of ridging marks and rough skin particularly in a low-cost manufacturing process.

  Furthermore, in the conventional manufacturing method, the annealing process is almost always taken after the hot rolling until the solution treatment, and this is also an obstacle to cost reduction.

  Also, with regard to paint baking, recently, from the viewpoint 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. There is an increasing tendency to shorten the baking time. However, in the case of aging Al-Mg-Si-based and Al-Mg-Si-Cu-based alloy plates obtained by the conventional general manufacturing method, curing at the time of coating baking (baking) There is a problem that it is difficult to obtain sufficient strength after baking.

  Here, in the aging Al-Mg-Si-based and Al-Mg-Si-Cu-based alloy plates obtained by a conventional general manufacturing method, if high press formability is to be obtained, bending workability (especially (Hemm bendability) is reduced, and if a low-cost process is attempted by omitting a simple process, there arises a problem that it is extremely difficult to suppress ridging marks and rough skin.

  Of the above-mentioned patent documents, Patent Document 1 discloses bending workability by adjusting the compound dispersion state, in particular, the particle diameter and number of Mg-Si based compounds by regulation such as homogenization and subsequent cooling rate. In the method of Patent Document 1, even if the compound dispersion state can be adjusted as described above, it is possible to sufficiently satisfy the recent severe requirements for bendability. It was difficult. Further, just adjusting the dispersion state of the compound as described in Patent Document 1 is insufficient to achieve both good hem bendability and press formability. In addition, it was insufficient for consideration of surface quality, particularly for preventing ridging marks and rough skin.

  On the other hand, in Patent Document 2, it is proposed to improve the bending workability by regulating the ratio of crystal grain boundaries in which the orientation difference between crystal grains is 15 ° or less. Although some improvement effect can be achieved with respect to bending workability, as a result of repeated experiments and examinations by the present inventors, the bendability in all directions of the rolled sheet is not improved even in this method. There was found. 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 there is a problem that sex occurs. Also, even if the elongation in the 45 ° direction with respect to the rolling direction is high, the elongation in the direction parallel to the rolling direction or in the direction perpendicular to the rolling direction may be low, and the anisotropy of the elongation may be significant. There is also concern about a decrease in press formability.

  This invention was made against the background of the above circumstances, and has appropriate strength, bending anisotropy and strength anisotropy are small, and has a good balance between press formability and bending workability. An aluminum alloy sheet for forming that has excellent ridging resistance even in a low-cost manufacturing process that is not performed, can impart good bake hardenability and high press formability, and has little room temperature aging, and It is an object of the present invention to provide a method capable of manufacturing such a plate reliably, stably and at a low cost on a mass production scale.

  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, the crystal orientation density of the cube orientation (cube orientation) is appropriately increased, and at the same time, not only the cube orientation density but also the crystal orientation density of Cu, S, and Bs belonging to the ND rotating cube, goth, and β fiber of the rolled texture. By controlling to an appropriate level based on the mutual relationship, deterioration of press workability and hem workability caused by anisotropy can be prevented, and good bake hardenability and aging resistance at room temperature It has been found that not only can change be obtained, but also ridging marks and rough skin resistance can be improved. 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.

The aluminum alloy sheet for forming according to the invention of claim 2 contains Mg 0.2 to 1.5% (mass%, the same shall apply hereinafter), Si 0.3 to 2.0%, and Ti 0.005 to 0.00. 3% alone or together with B500ppm or less, Mn 0.03-0.6%, Cr 0.01-0.4%, Zr 0.01-0.4%, V 0.01-0.4%, Fe0 0.03 to 1.0%, Zn 0.03 to 0.05% , one or more selected from among them, further Cu is regulated to 1.5% or less, the balance is Al and unavoidable An aluminum alloy made of impurities is used as a material, and the cube orientation density of crystal grains existing on the plate is D1, and {001} <of the orientations rotated from the cube orientation about the plate surface normal (hereinafter referred to as “ND”) 730> orientation (hereinafter referred to as “ND rotating cube The density of the orientation) is denoted by D2, the density of the orientation rotated 45 ° from the cube orientation with respect to the rolling direction as an axis (hereinafter referred to as the “Goss orientation”) is denoted by D3, and Cu belonging to the β fiber of the rolling texture, The sum of the S and Bs orientation densities is D4, and the following formulas (1) to (4) (the values of D1, D2, D3, and D4 for each orientation density all represent multiples of the random crystal orientation density)
D1 ≧ 168.4 (1)
D2 ≧ 18.9 (2)
D2 / D3 ≧ 7.5 (3)
D4 ≧ 9.1 (4)
Further, the 0, 90 ° ear ratio is 3% or more, and the crystal grain size is ASTM No. It is characterized by being 4.5 or more.

Furthermore, in the manufacturing method of the aluminum alloy plate for forming according to the invention of claim 2, when the aluminum alloy plate for forming according to claim 1 is manufactured, the ingot of the aluminum alloy having the above composition is 480 to 590 ° C. A homogenization treatment is performed at a temperature within the range for 1 hour or more, and in the cooling process, first, a temperature within a temperature range of 150 ° C. or higher and lower than 450 ° C. (hereinafter referred to as “first cooling point”) is 100 ° C./h. Rapid cooling at the above cooling rate, followed by a certain temperature within a temperature range from 150 ° C. to less than 450 ° C. from the first cooling point (hereinafter referred to as “second cooling point”) Is kept at a temperature range of 150 ° C. or higher and lower than 450 ° C. for at least 0.5 hour by slowly cooling at a cooling rate of less than 100 ° C./h. The hot rolling is started at a temperature of less than 450 ° C. and at least one rolling pass under a high pressure at a rolling rate of 40% or more per pass in the stage from a sheet thickness of 200 mm to 20 mm during the hot rolling process. The hot-rolled sheet thus obtained was subjected to cold rolling at a rolling rate of 30% or higher without annealing, and then subjected to a solution treatment at a temperature of 480 ° C. or higher, and then 100 ° C./min. Cooling to a temperature range of less than 150 ° C. and 50 ° C. or more at the above average cooling rate, followed by stabilizing treatment for 1 hour or more in a temperature range of less than 150 ° C. and 50 ° C. or more. .

The production method of molding an aluminum alloy plate of the invention of claim 3, in producing a molded aluminum alloy plate according to claim 1, said composition of the aluminum alloy ingot to the 480 to 590 ° C. A homogenization treatment is performed at a temperature within the range for 1 hour or more, and in the cooling process, first, a temperature within a temperature range of 150 ° C. or higher and lower than 450 ° C. (hereinafter referred to as “first cooling point”) is 100 ° C./h. By rapidly cooling at the above cooling rate and subsequently maintaining at a temperature in the range of 150 ° C. or higher and lower than 450 ° C., it is allowed to stay in that temperature range for at least 0.5 hours, and then 250 ° C. or higher and lower than 450 ° C. The number of rolling passes under high pressure with a rolling rate of 40% or more per pass is reduced in the stage from the thickness of 200 mm to 20 mm in the hot rolling process. The hot-rolled sheet obtained is subjected to cold rolling at a rolling rate of 30% or higher without annealing, and then subjected to a solution treatment at a temperature of 480 ° C. or higher and then 100 ° C. Cooling to a temperature range of less than 150 ° C. and 50 ° C. or more at an average cooling rate of / min or more, and subsequently performing stabilization treatment for 1 hour or more in a temperature range of less than 150 ° C. and 50 ° C. or more It is.

Method of manufacturing a molding aluminum alloy strip for the invention of claim 4, in producing a molded aluminum alloy plate according to claim 1, said composition of the aluminum alloy ingot to the 480-590 ° C. A homogenization treatment is performed at a temperature within the range for 1 hour or more, and in the cooling process, first, a temperature within a temperature range of 150 ° C. or higher and lower than 450 ° C. (hereinafter referred to as “first cooling point”) is 100 ° C./h. Rapid cooling at the above cooling rate, followed by a certain temperature within a temperature range from 150 ° C. to less than 450 ° C. from the first cooling point (hereinafter referred to as “second cooling point”) Is kept at a temperature range of 150 ° C. or higher and lower than 450 ° C. for at least 0.5 hour by slowly cooling at a cooling rate of less than 100 ° C./h. The hot rolling is started at a temperature of less than 450 ° C. and at least one rolling pass under a high pressure at a rolling rate of 40% or more per pass in the stage from a sheet thickness of 200 mm to 20 mm during the hot rolling process. The hot-rolled sheet obtained is subjected to cold rolling at a rolling rate of 30% or higher without annealing, and then subjected to a solution treatment at a temperature of 480 ° C. or higher and then 100 ° C./min or higher. It cools to the temperature range below 50 degreeC with the average cooling rate of, and is left to stand.

And the manufacturing method of the aluminum alloy plate for shaping | molding of invention of Claim 5 is 480-590 degreeC in the ingot of the aluminum alloy of the said component composition in manufacturing the aluminum alloy plate for shaping | molding processing of Claim 1. In the cooling process, a homogenization treatment is performed at a temperature within a range of 150 ° C. to a temperature within a temperature range of 150 ° C. to less than 450 ° C. (hereinafter referred to as “first cooling point”). Quenching at a cooling rate of h or higher, and subsequently maintaining at a temperature in the range of 150 ° C. or higher and lower than 450 ° C., allowing it to stay in that temperature range for at least 0.5 hours, then 250 ° C. or higher and 450 ° C. Rolling under high pressure with a rolling rate of 40% or more per pass is started at a stage from a thickness of 200 mm to 20 mm during the hot rolling process. The hot-rolled sheet obtained at least once is subjected to cold rolling at a rolling rate of 30% or higher without annealing, and then subjected to a solution treatment at a temperature of 480 ° C. or higher. It is characterized by cooling to a temperature range of less than 50 ° C. at an average cooling rate of at least ° C./min and leaving it to stand.

Furthermore, the manufacturing method of the aluminum alloy plate for forming according to the invention of claim 6 is the method for manufacturing the aluminum alloy plate for forming according to claim 4 or 5 , wherein the solution treatment is performed at a temperature of 480 ° C or higher. And after cooling to a temperature range of less than 50 ° C. at an average cooling rate of 100 ° C./min or more, and then performing a restoration treatment at a temperature within the range of 180 to 280 ° C. It is.

  The aluminum alloy sheet for forming according to the present invention has a small decrease in press formability due to strength anisotropy, a decrease in hemmability due to bending anisotropy, and a good balance between press formability and bending workability. Even without an intermediate annealing step, it is possible to suppress the occurrence of ridging marks and rough skin, and in addition, good paint bake hardenability and higher press formability can be imparted depending on the application, and there is little change over time at room temperature. Therefore, it is most suitable for automobile body sheets and the like that are used after painting and baking by pressing or hem processing. Further, according to the method for manufacturing a forming aluminum alloy plate of the present invention, the forming aluminum alloy plate having excellent performance as described above can be manufactured reliably and stably at a low cost on a mass production scale. it can.

Molding an aluminum alloy plate of the invention, A l-Mg-Si-based alloy or Al-Mg-Si-Cu-based alloy, ie Mg0.2~1.5%, Si0.3~2.0 And 0.005 to 0.3% of Ti alone or together with B500ppm or less, and Mn 0.03 to 0.6%, Cr 0.01 to 0.4%, Zr 0.01 to 0.4 %, V 0.01 to 0.4%, Fe 0.03 to 1.0%, Zn 0.03 to 0.05%, or one or more selected from Cu, and further Cu is 1.5 % is regulated in the following, it shall be the material an alloy balance of Al and unavoidable impurities.

The reasons for limiting the component composition of such Material alloy 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 press formability, particularly bending workability is lowered, the amount of Mg is set to be in the range of 0.2 to 1.5%. In order to improve the press 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 effect cannot be obtained sufficiently. On the other hand, if it exceeds 2.0%, coarse Si particles and coarse Mg-Si based intermetallic compounds are generated to increase the cube orientation density. For this reason, it becomes disadvantageous, and press formability, particularly bending workability is lowered. 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, V, Fe, Zn:
These elements are effective for improving strength, crystal grain refinement, aging (bake hardenability) and surface treatment, and any one or more of them are added. Among these, Mn, Cr, Zr, and V are elements that are effective in improving the strength, refining the crystal grains, and stabilizing the structure, but the Mn content is less than 0.03%, or the Cr content is If the content is less than 0.01% 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 Cr, Zr, V If the content 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 the formability, particularly hem bendability. In the range of 0.03 to 0.6%, Cr, Zr, and V were each in the range of 0.01 to 0.4%. Fe is also an element effective for strength improvement and crystal grain refinement, but if its content is less than 0.03%, a sufficient effect cannot be obtained, while if it exceeds 1.0%, many intermetallic compounds are obtained. May be produced, and press formability and bending workability may be deteriorated. Therefore, the amount of Fe is set within a range of 0.03 to 1.0%. In addition, when it is desired to minimize a decrease in bending workability, the Fe content is preferably in the range of 0.03 to 0.5%. Further, Zn is an element that contributes to improvement of strength through improvement of aging and is effective for improvement of surface treatment properties. However, if the addition amount of Zn is less than 0.03%, the above effect cannot be obtained sufficiently . If the content exceeds 05% , the moldability deteriorates, so the Zn content is set in the range of 0.03 to 0.05% .

Ti, B:
Since the addition of Ti is effective in preventing the rough surface of the final plate and improving ridging resistance through refinement of the ingot structure, this invention also adds Ti for refinement of the ingot structure. If less than 0.005%, a sufficient effect cannot be obtained. On the other hand, if it exceeds 0.3%, not only the effect of addition of Ti is saturated but also a coarse crystallized product may be formed. Within the range of 0.005 to 0.3%. The Ti addition amount is usually preferably in the range of 0.005 to less than 0.05%. Ti may be added alone, but by adding a small amount of B together with Ti, the effect of refining and stabilizing the ingot structure becomes more remarkable. Therefore, also in the case of this invention, it is permissible to add 500 ppm or less of B together with Ti.

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 1.5% 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, V, Fe, 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 small amount, and if it is 0.3% or less, the intended purpose is not particularly impaired.

  Furthermore, it is said that the addition of Sc is effective for refining the ingot structure. In the case of this invention, a small amount of Sc may be added, and within 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 optimize the balance between press formability and bending workability, it is necessary to reduce strength anisotropy and bending anisotropy, In order to improve the properties, it is extremely important not only to adjust the alloy composition as described above, but also to appropriately control the texture of the aluminum alloy plate as the final plate, particularly the crystal orientation density.

Here, in the present invention, the crystal orientation density of the final plate is controlled not only for controlling the grain boundary properties (small angle or large angle), but also for the entire slip deformation of the crystal accompanying plastic deformation of the aluminum alloy. The main purpose is to control. 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.

  Here, if the cube orientation density is simply increased, the formation of bending anisotropy, strength anisotropy, and ridging marks becomes remarkable, which may reduce the balance of material properties and may impair the plate appearance. Therefore, when the present inventors conducted further experiments and examinations, the cube orientation density was not simply increased, but the cube orientation density was appropriately increased, and at the same time, the ND rotation cube orientation density, the ND rotation cube orientation density, and the Goth orientation By controlling the ratio to the density and the orientation density of Cu, S, and Bs belonging to the component called β fiber to an appropriate level, the bending anisotropy results from the strength anisotropy and bending anisotropy. It has been found that the press formability and bending workability can be prevented from being lowered and the balance between the two can be improved most appropriately. Further, it has been found that by these controls, the occurrence of ridging marks and rough skin is suppressed, the appearance of the plate after molding is improved, and a practically satisfactory level is reached.

That is, the cube orientation density of crystal grains existing in the plate is D1, and the {001} <730> orientation (hereinafter referred to as “ND”) among the orientations rotated from the cube orientation about the plate normal (hereinafter referred to as “ND”). D2 is the density of the rotating cube orientation), and D3 is the density of the orientation rotated 45 ° from the cube orientation about the rolling direction (hereinafter referred to as the “Goss orientation”). The total of Cu, S, and Bs orientation densities is D4, and the following formulas (1) to (4) (all numerical values of D1, D2, D3, and D4 of each orientation density represent multiples of random crystal orientation density)
D1 ≧ 168.4 (1)
D2 ≧ 18.9 (2)
D2 / D3 ≧ 7.5 (3)
D4 ≧ 9.1 (4)
By controlling the crystal orientation density so as to satisfy the above condition, the above-mentioned actions and effects can be obtained.

Here, the expressions (1) and (2) are effective in improving the bending workability by appropriately increasing the cube orientation density and the ND rotating cube orientation density D2. The Goss orientation D3 is an orientation that often appears in aluminum materials, but it was found that this Goss orientation is an orientation that promotes bending anisotropy, and further experiments and studies were conducted. (3) As defined by the equation, by controlling the ratio D2 / D3 of the ND rotating cube orientation density D2 and the Goth orientation density D3 to be 7.5 or more , there is an effect in suppressing bending anisotropy. It became clear . Or (4) is a provision for the residual levels of β fiber component referred rolling texture, by regulating the residual levels of β fiber component by the equation (4), the cube orientation density It has the effect of suppressing the decrease in press formability due to excessive development and improving the balance between press formability and bending workability. Further, the regulation by equation (4) suppresses the occurrence of ridging marks and rough skin due to orientation dispersion. It is also effective. And by comprehensive regulation by these formulas (1), (2), (3), and (4), there is an effect to reduce the strength anisotropy and bending anisotropy. Such azimuth dispersion is also effective in suppressing the occurrence of ridging marks and rough skin.

  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 3% or more over the entire plate. That is, as described above, in the present invention, the crystal orientation density is defined by the equations (1) to (4), but the orientation density of other crystal orientations also affects the 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 crystal orientations other than the formulas (1) to (4) is evaluated and regulated by the 0 ° ear and the 90 ° ear. Specifically, when the 0 ° and 90 ° ear ratio of the cup is less than 3% based on the rolling direction, there is a possibility that good bending workability may not be obtained even if the conditions of the above-described formulas are satisfied. is there. Therefore, in the present invention, the ear rate is regulated as described above. In addition, although 0 degree and 90 degree ear rate do not prescribe | regulate an upper limit, normally 30% or less is desirable from a viewpoint of bending anisotropy and intensity | strength anisotropy suppression. In particular, in order to keep the balance of press formability and bending workability optimal, the ear rate is preferably in the range of 5 to 28%.

  Further, in order to improve bending workability and prevent rough skin, which is an appearance defect during press molding, it is necessary to make the crystal grain size fine. As a result of repeated experiments and examinations by the present inventors, it has been found that if the crystal grain size is 4.5 or more in terms of ASTM number, it has the effect of improving bending workability and preventing rough skin (appearance defects). Is defined in the present invention. In the case where the appearance is more important, a range of ASTM number 6.0 or more is preferable.

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

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

  The obtained ingot is cooled by performing a homogenization process. Here, the homogenization treatment removes segregation of additive elements in the ingot, or dissolves coarse second-phase particles, crystallized materials, etc. existing at the boundary between the cells and crystal grains of the ingot into the matrix phase. This is an important process for obtaining the required crystal orientation by organically combining with the hot rolling process and the solution forming process, and reducing the variation in product plate performance. When the temperature of the homogenization treatment is less than 480 ° C., the above-mentioned effects cannot be obtained sufficiently, while when the temperature exceeds 590 ° C., eutectic melting may occur, so the homogenization treatment is performed at a temperature in the range of 480 to 590 ° C. I decided to do it. The homogenization time is usually preferably in the range of 1 to 48 hours. If it is less than 1 hour, the effect of homogenization cannot be sufficiently obtained. On the other hand, if it exceeds 48 hours, only the cost is increased.

  As for cooling after the homogenization treatment, it is generally desirable to avoid coarsening of precipitates formed in the cooling process in order to obtain high bake hardenability. Has been proposed that the cooling after the homogenization process is performed at a large cooling rate in one stage, but as a result of repeated extensive experiments and studies by the present inventors, the increase in the cooling rate is certainly high. Although effective for obtaining curability, when this method is applied to the process of the present invention in which intermediate annealing is omitted, the crystal grain size becomes unstable in the plate thickness direction, and the variation in crystal grain size is remarkably large. It turns out that the problem which becomes large arises. If such a variation occurs, there is a problem in the rough skin resistance of the product plate, and there is a possibility that the high appearance quality of the automobile panel cannot be secured stably.

Therefore, in the manufacturing method of the present invention, in order to achieve both high bake hardenability and reliable suppression of rough skin, as specified in claims 2 to 5 , as a cooling process after homogenization treatment, a special process is performed. Thus, the two-stage cooling in this embodiment was applied. That is, as defined in claims 2 and 4 , in the cooling process after the homogenization treatment, first, as a first stage cooling, a temperature within a temperature range of 150 ° C. or higher and lower than 450 ° C. (first cooling point) And then rapidly cooled at a cooling rate of 100 ° C./h or higher, and subsequently to a temperature lower than the first cooling point and within a temperature range of 150 ° C. or higher and lower than 450 ° C. (second cooling point) 100 ° C./h Slow cooling is performed at a cooling rate of less than 150 ° C., thereby allowing it to stay in a temperature range of 150 ° C. or more and less than 450 ° C. for at least 0.5 hours, or as defined in claims 3 and 5 , Similarly, after rapidly cooling to the first cooling point, the temperature is continuously maintained within a temperature range of 150 ° C. or higher and lower than 450 ° C., and the temperature range of 150 ° C. or higher and lower than 450 ° C. is maintained for at least 0.5 hour or longer. And the letting distillates, by a combination of such two-stage cooling process, it becomes possible to achieve both high bake hardenability and surface roughening inhibiting.

Here, following the rapid cooling at a cooling rate of 100 ° C./h or higher up to the first stage cooling point defined in claim 3 or claim 5 , “in the temperature range of 150 ° C. or higher and lower than 450 ° C. `` Retain for 0.5 hour or longer within the temperature range '' means that the temperature is maintained at a substantially constant temperature within the temperature range, or is maintained at two or more different temperatures within the temperature range. This includes any case such as a case, a case where the temperature is slowly cooled within the temperature range, and a case where the temperature is reheated within the temperature range to gradually raise the temperature. It is only necessary to stay within the range for 0.5 hour or more. However, it is have you in the actual production site, slow cooling is preferred from the viewpoint of economy.

  Here, in the above description, the temperature range which is defined as the first cooling point and is retained for 0.5 hours or more after that is 150 ° C. or more and less than 450 ° C., but more stably high bake hardenability. Is preferably 200 ° C. or higher and lower than 450 ° C. in order to achieve both the prevention of skin roughness and the rough skin. Further, the residence time in the temperature range is preferably 1.5 hours or more, and more preferably 2 hours or more. By applying these preferable conditions, the grain size ASTM number 4.5 or more can be achieved more stably while ensuring high bake hardenability.

  As described above, after the homogenization treatment, the first cooling point of 150 ° C. or higher and lower than 450 ° C. is rapidly cooled at a cooling rate of 100 ° C./h or higher, and then the second stage cooling process is 150 ° C. or higher and lower than 450 ° C. Or at least 0.5 hour or more, preferably 1.5 hours or more, more preferably 2 hours or more within the temperature range (slow cooling or holding, or (Including various temperature histories such as heating) makes it possible to appropriately obtain the size and distribution of the simple Si, Mg—Si, and Mg—Si—Cu based compounds.

  In addition, when the cooling rate to the first cooling point is less than 100 ° C./h, precipitates are likely to be coarsened in a high temperature range, and the size and distribution of simple substance Si, Mg—Si, Mg—Si—Cu based compounds are inappropriate. Therefore, there is a concern that the bake hardenability and the moldability may be lowered, so that the first stage cooling is set to 100 ° C./h or more. Further, if the residence time in the temperature range of 150 ° C. or more and less than 450 ° C. in the second stage is less than 0.5 hours, the above-mentioned effect cannot be obtained sufficiently, so that the residence time is 0.5 It was set to more than time, preferably 1.5 hours or more, more preferably 2 hours or more. The upper limit of the residence time is not particularly restricted, but it is usually preferably within 48 hours in consideration of the influence on bake hardenability and productivity.

  As described above, after performing the two-stage cooling method after the homogenization treatment for the ingot, it is usual to perform hot rolling. Here, the hot rolling is started in a temperature range of 250 ° C. or higher and lower than 450 ° C. as described later, but the ingot that has undergone the two-stage cooling process after the homogenization treatment is cooled to less than 150 ° C. Even if the hot rolling is started immediately after the hot rolling start temperature of 250 ° C. or more and less than 450 ° C., or once cooled to less than 150 ° C., it is allowed to stand at room temperature and be chamfered as necessary. Then, it may be heated again to 250 ° C. or higher and lower than 450 ° C., and hot rolling may be started at that temperature.

  Here, when it is cooled to less than 150 ° C. and subjected to standing at room temperature, chamfering, etc. as necessary, and then reheating, for the residence time in the temperature range of 150 to 450 ° C. in the temperature rising process, The residence time specified in claims 3, 4, 5, and 6 of the present invention is not counted. The reason for this is that when the temperature is raised from a temperature range of less than 150 ° C., a high-density aging structure is inevitably formed by low-temperature aging, and thus a high-density aging structure is once formed in the low-temperature range. For example, even if the subsequent residence time in the temperature range of 150 to 450 ° C. is 0.5 hours or more, the size and distribution of the appropriate simple substance Si, Mg—Si, Mg—Si—Cu based compound are This is because it may not be obtained.

  In addition, even in a thin continuous casting material that does not require a hot rolling process, in order to achieve both high bake hardening and suppression of rough skin, as in the method of the present invention, up to a temperature range of 150 ° C. or higher and lower than 450 ° C. Rapid cooling and subsequent slow cooling within the temperature range, or rapid cooling to a temperature range of 150 ° C. or higher and lower than 450 ° C. and residence in the temperature range are necessary. It may be cooled to less than that and allowed to stand at room temperature if necessary before cold rolling.

  Further, the process for the ingot that has been subjected to homogenization and cooled in two stages will be described in detail.

In the case of the method of the present invention, the ingot after homogenization and two-stage cooling is processed by any one of the following processes (a), (b), and (c) to finish the final plate. .
(A) Process defined in claims 2 and 3 : hot rolling-cold rolling-solution treatment-cooling (less than 150 ° C, 50 ° C or more)-stabilization treatment,
(B) Process defined in claims 4 and 5 : hot rolling-cold rolling-solution treatment-cooling (less than 50 ° C.)-Standing at room temperature (c) process defined in claim 6 : hot rolling -Cold rolling-Solution treatment-Cooling (less than 50 ° C)-Standing at room temperature-Restoration treatment

  Here, in any of the processes (a) to (c), the hot rolling needs to be performed so as to satisfy the following conditions (1) and (2). (1) The hot rolling start temperature is set to a temperature range of 250 ° C. or higher and lower than 450 ° C. (2) At least one pass at a stage from a sheet thickness of 200 mm to 20 mm during the hot rolling process, and a pass under a high pressure with a rolling rate of 40% or more is performed.

  Of the above hot rolling conditions, first, the condition (1), that is, setting the hot rolling start temperature to less than 450 ° C., suppresses recrystallization of the material during hot rolling, and the required crystal orientation density. This is an indispensable condition for improving ridging resistance at the same time. If hot rolling is started at a high temperature of 450 ° C. or higher, the ridging resistance cannot be improved, and the required final plate strength may not be obtained. On the other hand, if the hot rolling start temperature is less than 250 ° C., the hot rolling itself becomes difficult. Therefore, the hot rolling start temperature was set to 250 ° C. or higher and lower than 450 ° C. A more preferable hot rolling start temperature is in the range of 250 to 400 ° C.

The condition (2) is an indispensable condition for suppressing the recrystallization of the material during hot rolling and obtaining the required crystal orientation density in combination with the condition (1). In other words, the condition (2) is meaningful in that a large deformation is applied to the fibrous structure in an almost non-recrystallized state under a one-pass pressure, and thereby the intended crystal rotation can be achieved. . Furthermore, in addition to optimizing the size and distribution of simple substance Si, Mg—Si, Mg—Si—Cu based compounds by two-stage cooling after the homogenization treatment defined in the present invention, the working structure during hot rolling Thus, the recovery and recrystallization behavior are controlled, whereby not only cube orientation but also proper accumulation of orientation different from cube orientation can be obtained on the final plate. That is, the orientation density and ratio defined in claim 1 are obtained, and such orientation dispersion is effective in improving ridging resistance, rough skin, bending anisotropy, and strength anisotropy.

  Also, here, if the rolling rate is less than 40% when the plate thickness is 200 to 20 mm, the above effect cannot be obtained. Therefore, at least one pass is set to a rolling rate of 40% or more in the plate thickness step. There is a need. More preferably, the rolling rate of at least one pass in the above stage is 50% or more. The end temperature of the hot rolling is not particularly specified, but usually the effect of the present invention is not impaired as long as it is in the range of 150 ° C to 350 ° C.

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

  After performing hot rolling as described above, in any of the processes (a), (b), and (c), cold rolling with a rolling rate of 30% or more is performed without performing intermediate annealing. Use the required product thickness.

  This cold rolling not only has an effect of accumulating strain in the plate and refines the crystal grains by the subsequent solution treatment, but also has a certain influence on the formation of the crystal orientation of the final plate. If the rolling rate of cold rolling is less than 30%, the crystal grain size and grain orientation density specified in the present invention may not be obtained.

  After the cold rolling, the solution treatment is performed at a temperature of 480 ° C. or higher in any of the processes (a) to (c). This solution treatment is carried out by dissolving Mg-Si, Mg-Si-Cu compounds, elemental Si, etc. in a matrix in an Al-Mg-Si or Al-Mg-Si-Cu alloy and baking it. This is an important process for imparting curability and improving strength after baking. This process also contributes to improving the ductility and bendability by lowering the distribution density of the second phase particles by solid solution of Mg-Si, Mg-Si-Cu compounds, simple substance Si particles, etc. Further, it is an important step for obtaining a desired crystal orientation finally by recrystallization and obtaining good formability (bending workability, press formability). Here, when the solution treatment temperature is less than 480 ° C., the above effect cannot be obtained sufficiently.

  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 defined, but it is usually preferably 590 ° C. or less in consideration of the possibility of eutectic melting and coarsening of recrystallized grains. The solution treatment time is not particularly limited. However, if it exceeds 5 minutes, the solution effect is saturated, not only the economic efficiency is impaired, but also the crystal grains may be coarsened. Is preferably within 5 minutes.

  As for cooling after solution treatment, cooling is usually performed at 100 ° C./min or more in order to prevent a large amount of Mg—Si, Mg—Si—Cu compounds, or simple substance Si from being precipitated at grain boundaries during cooling. Cooling (quenching) to a temperature range of 150 ° C. or lower by cooling at a speed. The lower limit of the quenching temperature range varies depending on the process, and is set to 50 ° C. or higher in the process (a) and lower than 50 ° C. in the processes (b) and (c). Here, when the cooling rate after the solution treatment is less than 100 ° C./min, press formability, particularly bending workability is lowered, and at the same time, bake hardenability is lowered, and sufficient strength improvement at the time of coating baking cannot be expected.

When the bake hardenability (BH property) is emphasized after the solution treatment as described above, the stabilization treatment is performed according to the process (a) defined in claims 2 and 3 . That is, after solution treatment at a temperature of 480 ° C. or higher and cooling (quenching) to a temperature range of 50 ° C. or higher and lower than 150 ° C. at a cooling rate of 100 ° C./min or higher, a temperature range of less than 50 ° C. (so-called room temperature) The stabilization treatment is performed within this temperature range (less than 50 to 150 ° C.) before the temperature drops to the upper limit. The holding time in the temperature range of 50 to less than 150 ° C. in this stabilization treatment is not particularly limited, but normally it is desirable to hold for 1 hour or longer, and cooling (slow cooling) over 1 hour or more within that temperature range. You may do it.

On the other hand, when emphasis is placed on formability, especially press formability, rather than bake hardenability, the stabilization treatment as described above is not performed after the solution treatment. This is the process (b) defined in claims 4 and 5 . That is, in this case, after the solution treatment at 480 ° C. or more, the solution is cooled to a temperature range of less than 50 ° C. (usually 0 ° C. or more) at a cooling rate of 100 ° C./min or more, and a temperature range of 0 to less than 50 ° C. Leave at room temperature.

  The reasons for performing the solution treatment as described above and quenching in a temperature range of 50 to less than 150 ° C. or in a temperature range of less than 50 ° C. and then holding, annealing, and leaving in each temperature range are as follows. .

  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, but since the decrease in ductility is small, it is advantageous for press molding. 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 hemmability and press formability deteriorate. In addition, the room temperature aging resistance may deteriorate. Therefore, from the viewpoint of balance between hemmability, press formability, paint bake hardenability, and room temperature aging resistance, solution treatment-quenching (process (b)), solution treatment-quenching-stabilization treatment (process ( It is necessary for a)) to satisfy the above conditions, and it is only necessary to determine which process is to be applied according to the application and required characteristics.

  Furthermore, as shown as the process (b) above, after a solution treatment at 480 ° C. or higher and quenching to a temperature range of less than 50 ° C., and if allowed to stand in a temperature range of 0 to 50 ° C., 180 ° C. The restoration process may be performed at ˜280 ° C., which is the process (c) defined in claim 7. The reason why the restoration process is performed in the process (c) is as follows. That is, a room temperature cluster formed by cooling to a room temperature of less than 50 ° C. contributes to strength. P. Difficult to paint bake hardenability because it is difficult to shift to the zone, but the bake hardenability is restored by heat treatment at 180 to 280 ° C for a short time (usually within 5 minutes is preferable), and bending workability is improved. There is an effect to make. Therefore, this process (c) is applied when emphasizing the bake hardenability and bending workability.

  As described above, an optimal mass production manufacturing system can be constructed by selecting one of the processes (a), (b), and (c) in accordance with the application (required characteristics) and production equipment.

  Here, an important measurement method and display method related to the method of the present invention will be described below, but the others are based on the method of the embodiment.

The crystal orientation density measurement and calculation method defined in claim 1 is as follows.

Cube orientation density (C _1/10 ) at a position 1/10 of the plate thickness from the plate surface, cube orientation density at a position _1/4 (C _1/4 ), cube orientation density at a position 1/2 (C _{1 / 2} ) was determined, and the total was defined as D1. Similarly, for the ND rotating cube orientation density D2, the ND rotating cube orientation density N _{1/10 at} the position 1/10 of the plate thickness from the plate surface, and the ND rotating cube orientation density N _{1/4 at} the position of _1/4 , 1 / The total of the ND rotating cube orientation density N _1/2 at position 2 was used. Similarly for the Goth orientation density D3, the Goth orientation density G _{1/10 at} a position 1/10 of the thickness from the plate surface, the Goth orientation density G _{1/4 at} a position _1/4 , and the Goth orientation at a position 1/2. It was set as the sum of density G1 _{/ 2} . Further, regarding the total density D4 of Cu orientation, S orientation, and Bs orientation belonging to the β fiber, the density Cu _1/10 , S _1/10 , Bs of each orientation at a position 1/10 of the plate thickness from the plate surface is similarly applied. _1/10 , density Cu _{1/4 in} each orientation at a position 1/4 from the plate surface, S _1/4 , B _1/4 , density Cu _{1/2 in} each orientation at a position 1/2 from the plate surface, It calculated _| required from the sum total of S1 _{/ 2} and B1 _{/ 2} . That is, D1 = C _1/10 + C _1/4 + C _1/2 D2 = N _1/10 + N _1/4 + N _1/2 D3 = G _1/10 + G _1/4 + G _1/2 D4 = (Cu _{1 / 10} + S _1/10 + Bs _1/10 ) + (Cu _1/4 + S _1/4 + Bs _1/4 ) + (Cu _1/2 + S _1/2 + Bs _1/2 ).

  For these measurements, an incomplete pole figure of {100}, {110}, {111} is measured by the X-ray diffraction Schertz reflection method using an X-ray diffractometer. An 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, various orientation densities were obtained as multiples of the sample having a random orientation. In this invention, the crystal orientation density is all based on three-dimensional crystal orientation analysis (ODF).

Here, the cube orientation is {001} <100> as the representative orientation, the Goss orientation is {011} <100> as the representative orientation, and the Cu orientation is {112} <111> as the representative orientation. , S orientation is {123} <634> as the representative orientation, and Bs orientation is {011} <211> as the representative orientation. Although there are various ND rotating cube orientations, in the present invention, as shown in the embodiments described later, the {001} <730> orientation is the representative orientation. In addition, since there is usually an azimuth dispersion having a certain angle centered on the azimuth, the present invention takes the maximum azimuth density within a rotation range of 15 ° around the azimuth, and each represents a representative value of the azimuth density. It was.

  Crystal grain size: ASTM number was calculated by the cutting method based on the image mapped by the EBSP (EBSD) method on the rolled surface of the plate (skin skin). A crystal boundary with a misorientation of 5 ° or more was regarded as a grain boundary.

  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 A5 within the 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 540 ° C. for 5 hours. After the homogenization treatment, two-stage cooling was performed, and then subjected to a hot rolling process, and further cold rolling (final cold rolling) was performed. The production numbers 1 to 8 in Tables 2 to 3 show the conditions from the two-stage cooling after the homogenization treatment to hot rolling and cold rolling.

  Here, the two-stage cooling after the homogenization treatment was performed as follows.

  That is, in production number 1, it was subjected to hot rolling immediately from the second cooling end temperature of 340 ° C. In production number 2, a 300 ° C. × 2 hour 300 ° C. holding treatment was further performed from the second cooling end temperature of 300 ° C., followed by hot rolling. Further, in production number 3, the temperature was raised from the second cooling end temperature of 305 ° C. to 320 ° C. at a rate of 15 ° C./h, a holding treatment was performed at this temperature for 1 hour, and then subjected to hot rolling. In production number 4, after the second cooling end temperature of 150 ° C. was once air-cooled to room temperature, the temperature was raised again to 300 ° C. and then subjected to hot rolling. In addition, the total residence time (6.00 hours) in the temperature range of 150 ° C. or higher and lower than 450 ° C. in the production number 4 passes the temperature range of 150 ° C. or higher and lower than 450 ° C. at the time of reheating from less than 150 ° C. Time is not counted. On the other hand, in production numbers 5 to 8, after air-cooling once from the first cooling end temperature to room temperature, the temperature was raised again to the hot rolling start temperature shown in Table 3 and subjected to hot rolling. The total residence time in the temperature range of 150 ° C. or more and less than 450 ° C. in each of these production numbers 5 to 8 is a temperature of 150 ° C. or more and less than 450 ° C. at the time of reheating from room temperature to the hot rolling start temperature. The time to pass through the area was not counted.

  Here, production numbers 5, 6, 7, and 8 all have a first cooling end temperature of less than 150 ° C., and production number 8 slows down the first stage cooling rate, and all are defined in the present invention. It is out of range.

  Further, after the solution treatment as shown in Table 3, the stabilization process is performed in the examples of production numbers 1, 2, 5, and 6, and the stabilization process is performed in the examples of production numbers 3 and 7. Without performing, it was allowed to stand as it was after cooling (quenching) after the solution treatment, and then the restoration treatment was performed. Furthermore, in the examples of production numbers 4 and 8, no stabilization treatment is performed after solution treatment-cooling. The solution was left at room temperature with cooling (quenching) after the solution treatment.

  The aluminum alloy plate (product plate) obtained as described above was examined for crystal grain size and texture (crystal orientation density) as follows.

  Crystal grain size: ASTM number was calculated by cutting method based on image mapped by EBSP (EBSD) method on rolled surface of plate. A crystal boundary line with a misorientation of 5 ° or more was regarded as a grain boundary.

Texture (crystal orientation density): A plate having a thickness of 1 mm and etched to various depths from the surface toward the center of the plate thickness with an aqueous NaOH solution was used as a measurement sample. Then, the cube orientation density (C _1/10 ) at a position of 100 μm from the plate surface, the cube orientation density (C _1/4 ) at a position of 250 μm, and the cube orientation density (C _1/2 ) at a position of 500 μm are obtained, and the total Was set to D1. Similarly for the ND rotating cube orientation density D2, the ND rotating cube orientation density N _{1/10 at} a position of 100 μm from the plate surface, the ND rotating cube orientation density N _{1/4 at} a position of 250 μm, and the ND rotating cube orientation at a position of 500 μm. The total density N _1/2 was used. Similarly for the Goth orientation density D3, the Goth orientation density G _{1/10 at} a position 1/10 of the thickness from the plate surface, the Goth orientation density G _{1/4 at} a position _1/4 , and the Goth orientation at a position 1/2. It was set as the sum of density G1 _{/ 2} . Further, regarding the total density D4 of Cu orientation, S orientation, and Bs orientation belonging to β fiber, the density Cu _1/10 , S _1/10 , Bs _1/10 , of each orientation at a position of 100 μm from the surface of the plate is similarly applied. Densities Cu _1/4 , S _1/4 , B _1/4 at positions 250 μm from the plate surface, densities Cu _1/2 , S _1/2 , B _{1 /} at positions 500 μm from the plate surface Obtained from the sum of _two . That is,
D1 = C _1/10 + C _1/4 + C _1/2
D2 = N _1/10 + N _1/4 + N _1/2
D3 = G _1/10 + G _1/4 + G _1/2
D4 = (Cu _1/10 + S _1/10 + Bs _1/10 ) + (Cu _1/4 + S _1/4 + Bs _1/4 ) + (Cu _1/2 + S _1/2 + Bs _1/2 )
It was.

Although there are various ND rotating cube orientations, in this embodiment , {001} <730> is set as the representative orientation among the ND rotating cube orientations. The maximum value within the 15 ° range was taken and displayed.

  These orientation density measurement results are shown in Table 4.

  Further, each plate obtained as described above was left at room temperature (25 ° C.) for 3 months in consideration of the aging of the room temperature, and then the strength of the plate before paint baking was evaluated by the tensile test and the ear by the cup drawing test. Rate, overhang height by punch overhang test, ridging mark evaluation, and hem workability evaluation by bending test. Further, after stretching each 2%, a coating baking (baking) treatment was performed at 170 ° C. for 20 minutes, a tensile test was performed, and a 0.2% proof stress value was measured as a mechanical strength. Specific measurement methods and evaluation methods are as follows.

  Ear ratio measurement: After applying lubricating oil 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 holding force 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.

  Evaluation of hem workability: Bending specimens are collected in three directions of 0 °, 45 °, and 90 ° within the plate surface with respect to the rolling direction of the material, stretched by 10%, and then tightly bent at 180 °, visually. Thus, the occurrence of cracks was observed. Here, a circle indicates that there is no crack, and a cross indicates that there is a crack.

  Evaluation of generation of ridging mark: An overhang was formed to a height of 30 mm with a spherical head punch having a diameter of 100 mm, and the streaks (unevenness) along the rolling direction formed on the surface were visually determined. A circle indicates no muscle or a weak muscle, and a cross indicates a strong muscle. If the streak is strong here, the appearance of the automobile outer plate is inappropriate.

  Evaluation of occurrence of rough skin: Overhang molding was performed up to a height of 30 mm with a spherical punch having a diameter of 100 mm, and the roughness of the surface was visually determined. A circle indicates a non-rough state, and a cross indicates a strong rough state. If the skin is rough, it is inappropriate as the appearance of the automobile outer plate.

  Overhang test: A masking film was applied to 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 an overhang test with Johnson wax (trade name) applied, and the maximum overhang height was examined. A punch having a ball head punch diameter of 100 mm was used.

  These test results and evaluation results are shown in Tables 5 and 6.

  In the examples of production numbers 1 to 4, the alloy component composition is within the range defined by the present invention, and the production process conditions are also within the range defined by the present invention. All satisfy the conditions specified in the present invention, but in these cases, the crystal grains are fine, there is no rough skin, the ridging resistance is good, and the overhang height which is an index of moldability is high, Bend anisotropy is small and hemmability is excellent. Among these, the examples of production numbers 1 to 3 have high bake hardenability and exhibited sufficient bake hardenability during paint baking, while production number 4 was slightly low in bake hardenability but excellent in overhanging properties.

  On the other hand, in the examples of production numbers 5 to 8, the alloy component composition is within the range specified in the present invention, but any of the production process conditions is outside the range of the present invention, and the crystal orientation density, Any of the crystal grain size conditions or the like did not satisfy the conditions specified in the present invention. Among these, in the case of the production number 5, the crystal grains were coarse and rough skin was generated. The overhang height was also inferior. Further, the hemmability in the 45 ° direction was inferior. In the case of production number 6, the crystal grains were rough and rough skin was generated. Overhang height and hem workability in 45 ° direction were inferior. Further, in the case of production number 7, the crystal grains were rough and rough skin was generated. Overhang height and hem workability in all directions were inferior. In the case of production number 8, there is no problem in crystal grain size, rough skin, etc., heme workability is good, but ridging resistance and overhang height are inferior, and overall strength is low, and three directions Strength anisotropy was also observed.

Claims (6)

Mg 0.2-1.5% (mass%, the same shall apply hereinafter), Si 0.3-2.0%, Ti 0.005-0.3% alone or with B500 ppm or less, and Mn 0. 03~0.6%, Cr0.01~0.4%, Zr0.01~0.4% , V0.01~0.4%, Fe0.03~1.0%, Zn0.03~ 0.05 contain one or two or more species selected from among%, more Cu is regulated to 1.5% or less, an aluminum alloy and the balance of Al and unavoidable impurities is a material present in the plate crystals Of the orientations rotated from the cube orientation around the plane normal (hereinafter referred to as “ND”) with D1 as the cube orientation density of the grains, the {001} <730> orientation (hereinafter referred to as “ND rotated cube orientation”) The density is set to D2, and the cue is set with the rolling direction as the axis. The density of an orientation rotated 45 ° from the orientation (hereinafter referred to as the “Goss orientation”) is D3, and the total density of Cu, S, Bs orientations belonging to the β fiber of the rolling texture is D4, and the following (1) Formula (4) (All numerical values of D1, D2, D3, and D4 in each orientation density represent multiples of random crystal orientation density)
D1 ≧ 168.4 (1)
D2 ≧ 18.9 (2)
D2 / D3 ≧ 7.5 (3)
D4 ≧ 9.1 (4)
Further, the 0, 90 ° ear ratio is 3% or more, and the crystal grain size is ASTM No. An aluminum alloy plate for forming, which is 4.5 or more. In producing the aluminum alloy sheet for forming according to claim 1, the aluminum alloy ingot of the above component composition is subjected to a homogenization treatment for 1 hour or more at a temperature in the range of 480 to 590 ° C., and its cooling process First, rapid cooling is performed at a cooling rate of 100 ° C./h or higher to a certain temperature within the temperature range of 150 ° C. or higher and lower than 450 ° C. (hereinafter referred to as “first cooling point”), and then from the first cooling point, Slowly cool to a temperature lower than the first cooling point and within a temperature range of 150 ° C. or higher and lower than 450 ° C. (hereinafter referred to as “second cooling point”) at a cooling rate of less than 100 ° C./h. To hold in the temperature range of 150 ° C. or higher and lower than 450 ° C. for at least 0.5 hour, and then start hot rolling at a temperature of 250 ° C. or higher and lower than 450 ° C., and during the hot rolling process At least one rolling pass under a high pressure with a rolling rate of 40% or more per pass at a stage from a thickness of 200 mm to 20 mm is performed, and the obtained hot rolled plate is 30% or more without annealing. After performing cold rolling at a rolling rate of 480 ° C. or higher, solution treatment is performed at a temperature of 480 ° C. or higher, and then cooled to a temperature range of less than 150 ° C. and 50 ° C. or higher at an average cooling rate of 100 ° C./min or higher, A method for producing an aluminum alloy sheet for forming, characterized by subsequently performing a stabilization treatment for 1 hour or more in a temperature range of less than 150 ° C. and 50 ° C. or more. In producing the aluminum alloy sheet for forming according to claim 1 , the aluminum alloy ingot of the above component composition is subjected to a homogenization treatment for 1 hour or more at a temperature in the range of 480 to 590 ° C., and its cooling process First, it is rapidly cooled at a cooling rate of 100 ° C./h or higher to a temperature within a temperature range of 150 ° C. or higher and lower than 450 ° C. (hereinafter referred to as “first cooling point”), and subsequently 150 ° C. or higher and lower than 450 ° C. By maintaining at a temperature within the range, the sheet is allowed to stay within the temperature range for at least 0.5 hours, and then hot rolling is started at a temperature of 250 ° C. or higher and lower than 450 ° C., and the plate is in the process of hot rolling A rolling pass under a high pressure at a rolling rate of 40% or more per pass at a stage from a thickness of 200 mm to 20 mm is performed at least once, and the obtained hot rolled sheet is subjected to 3 without annealing. After performing cold rolling at a rolling rate of not less than 100%, solution treatment is performed at a temperature of 480 ° C or higher, and then cooled to a temperature range of less than 150 ° C and 50 ° C or higher at an average cooling rate of 100 ° C / min or higher. Then, a method for producing an aluminum alloy plate for forming, characterized by performing a stabilization treatment for 1 hour or more in a temperature range of less than 150 ° C. and 50 ° C. or more. In producing the aluminum alloy sheet for forming according to claim 1 , the aluminum alloy ingot of the above component composition is subjected to a homogenization treatment for 1 hour or more at a temperature in the range of 480 to 590 ° C., and its cooling process First, rapid cooling is performed at a cooling rate of 100 ° C./h or higher to a certain temperature within the temperature range of 150 ° C. or higher and lower than 450 ° C. (hereinafter referred to as “first cooling point”), and then from the first cooling point, Slowly cool to a temperature lower than the first cooling point and within a temperature range of 150 ° C. or higher and lower than 450 ° C. (hereinafter referred to as “second cooling point”) at a cooling rate of less than 100 ° C./h. To hold in the temperature range of 150 ° C. or higher and lower than 450 ° C. for at least 0.5 hour, and then start hot rolling at a temperature of 250 ° C. or higher and lower than 450 ° C., and during the hot rolling process At least one rolling pass under a high pressure with a rolling rate of 40% or more per pass at a stage from a thickness of 200 mm to 20 mm is performed, and the obtained hot rolled plate is 30% or more without annealing. After performing cold rolling at a rolling rate of 480 ° C., solution treatment is performed at a temperature of 480 ° C. or higher, and then cooled to a temperature range of less than 50 ° C. at an average cooling rate of 100 ° C./min or more and left to stand. A method for producing an aluminum alloy sheet for forming. In producing the aluminum alloy sheet for forming according to claim 1 , the aluminum alloy ingot of the above component composition is subjected to a homogenization treatment for 1 hour or more at a temperature in the range of 480 to 590 ° C., and its cooling process First, it is rapidly cooled at a cooling rate of 100 ° C./h or higher to a temperature within a temperature range of 150 ° C. or higher and lower than 450 ° C. (hereinafter referred to as “first cooling point”), and subsequently 150 ° C. or higher and lower than 450 ° C. By maintaining at a temperature within the range, the sheet is allowed to stay within the temperature range for at least 0.5 hours, and then hot rolling is started at a temperature of 250 ° C. or higher and lower than 450 ° C., and the plate is in the process of hot rolling A rolling pass under a high pressure at a rolling rate of 40% or more per pass at a stage from a thickness of 200 mm to 20 mm is performed at least once, and the obtained hot rolled sheet is subjected to 3 without annealing. After cold rolling at a rolling rate of at least%, solution treatment is performed at a temperature of 480 ° C or higher, and then cooled to a temperature range of less than 50 ° C at an average cooling rate of 100 ° C / min or higher and left to stand. 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 4 or Claim 5 ,
After the solution treatment is performed at a temperature of 480 ° C. or higher, after cooling to a temperature range of less than 50 ° C. at an average cooling rate of 100 ° C./min or higher, the solution is further treated at a temperature in the range of 180 to 280 ° C. A method for producing an aluminum alloy sheet for forming, characterized by performing a restoration process.